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1

Geometric optimization  

SciTech Connect

An algorithm is presented which describes an application independent method for reducing the number of polygonal primitives required to faithfully represent an object. Reducing polygon count without a corresponding reduction in object detail is important for: achieving interactive frame rates in scientific visualization, reducing mass storage requirements, and facilitating the transmission of large, multi-timestep geometric data sets. This paper shows how coplanar and nearly coplanar polygons can be merged into larger complex polygons and re-triangulated into fewer simple polygons than originally required. The notable contributions of this paper are: (1) a method for quickly grouping polygons into nearly coplanar sets, (2) a fast approach for merging coplanar polygon sets and, (3) a simple, robust triangulation method for polygons created by 1 and 2. The central idea of the algorithm is the notion of treating polygonal data as a collection of segments and removing redundant segments to quickly form polygon hulls which represent the merged coplanar sets.

Hinker, P.; Hansen, C.

1993-09-01

2

OPTIMIZATION OF THE GEOMETRICAL PARAMETERS OF A BONDED STIFFENER: FINITE ELEMENT ANALYSIS  

Microsoft Academic Search

SUMMARY: A numerical study analyses important fabrication parameters for adhesive bonding of stiffened plates. The focus of this study lies on two parameters: the length and the thickness of the adhesive bond. Finite element analyses for four typical load cases are applied to a chosen test case, bonding two aluminium specimens. The analyses reveal most suitable values for the length

G. Mohamad; France V. Bertram; Germanischer Lloyd

3

Geometric optimization of thermal systems  

NASA Astrophysics Data System (ADS)

The work in chapter 1 extends to three dimensions and to convective heat transfer the constructal method of minimizing the thermal resistance between a volume and one point. In the first part, the heat flow mechanism is conduction, and the heat generating volume is occupied by low conductivity material (k 0) and high conductivity inserts (kp) that are shaped as constant-thickness disks mounted on a common stem of kp material. In the second part the interstitial spaces once occupied by k0 material are bathed by forced convection. The internal and external geometric aspect ratios of the elemental volume and the first assembly are optimized numerically subject to volume constraints. Chapter 2 presents the constrained thermodynamic optimization of a cross-flow heat exchanger with ram air on the cold side, which is used in the environmental control systems of aircraft. Optimized geometric features such as the ratio of channel spacings and flow lengths are reported. It is found that the optimized features are relatively insensitive to changes in other physical parameters of the installation and relatively insensitive to the additional irreversibility due to discharging the ram-air stream into the atmosphere, emphasizing the robustness of the thermodynamic optimum. In chapter 3 the problem of maximizing exergy extraction from a hot stream by distributing streams over a heat transfer surface is studied. In the first part, the cold stream is compressed in an isothermal compressor, expanded in an adiabatic turbine, and discharged into the ambient. In the second part, the cold stream is compressed in an adiabatic compressor. Both designs are optimized with respect to the capacity-rate imbalance of the counter-flow and the pressure ratio maintained by the compressor. This study shows the tradeoff between simplicity and increased performance, and outlines the path for further conceptual work on the extraction of exergy from a hot stream that is being cooled gradually. The aim of chapter 4 was to optimize the performance of a boot-strap air cycle of an environmental control system (ECS) for aircraft. New in the present study was that the optimization refers to the performance of the entire ECS system, not to the performance of an individual component. Also, there were two heat exchangers, not one, and their relative positions and sizes were not specified in advance. This study showed that geometric optimization can be identified when the optimization procedure refers to the performance of the entire ECS system, not to the performance of an individual component. This optimized features were robust relative to some physical parameters. This robustness may be used to simplify future optimization of similar systems.

Alebrahim, Asad Mansour

2000-10-01

4

Evolutionary Optimization of a Geometrically Refined Truss  

NASA Technical Reports Server (NTRS)

Structural optimization is a field of research that has experienced noteworthy growth for many years. Researchers in this area have developed optimization tools to successfully design and model structures, typically minimizing mass while maintaining certain deflection and stress constraints. Numerous optimization studies have been performed to minimize mass, deflection, and stress on a benchmark cantilever truss problem. Predominantly traditional optimization theory is applied to this problem. The cross-sectional area of each member is optimized to minimize the aforementioned objectives. This Technical Publication (TP) presents a structural optimization technique that has been previously applied to compliant mechanism design. This technique demonstrates a method that combines topology optimization, geometric refinement, finite element analysis, and two forms of evolutionary computation: genetic algorithms and differential evolution to successfully optimize a benchmark structural optimization problem. A nontraditional solution to the benchmark problem is presented in this TP, specifically a geometrically refined topological solution. The design process begins with an alternate control mesh formulation, multilevel geometric smoothing operation, and an elastostatic structural analysis. The design process is wrapped in an evolutionary computing optimization toolset.

Hull, P. V.; Tinker, M. L.; Dozier, G. V.

2007-01-01

5

Interplay between Peptide Bond Geometrical Parameters in Nonglobular Structural Contexts  

PubMed Central

Several investigations performed in the last two decades have unveiled that geometrical parameters of protein backbone show a remarkable variability. Although these studies have provided interesting insights into one of the basic aspects of protein structure, they have been conducted on globular and water-soluble proteins. We report here a detailed analysis of backbone geometrical parameters in nonglobular proteins/peptides. We considered membrane proteins and two distinct fibrous systems (amyloid-forming and collagen-like peptides). Present data show that in these systems the local conformation plays a major role in dictating the amplitude of the bond angle N-C?-C and the propensity of the peptide bond to adopt planar/nonplanar states. Since the trends detected here are in line with the concept of the mutual influence of local geometry and conformation previously established for globular and water-soluble proteins, our analysis demonstrates that the interplay of backbone geometrical parameters is an intrinsic and general property of protein/peptide structures that is preserved also in nonglobular contexts. For amyloid-forming peptides significant distortions of the N-C?-C bond angle, indicative of sterical hidden strain, may occur in correspondence with side chain interdigitation. The correlation between the dihedral angles ??/? in collagen-like models may have interesting implications for triple helix stability.

Esposito, Luciana; De Simone, Alfonso; Vitagliano, Luigi

2013-01-01

6

Minimizing stellarator turbulent transport by geometric optimization  

NASA Astrophysics Data System (ADS)

Up to now, a transport optimized stellarator has meant one optimized to minimize neoclassical transport,ootnotetextH.E. Mynick, Phys. Plasmas 13, 058102 (2006). while the task of also mitigating turbulent transport, usually the dominant transport channel in such designs, has not been addressed, due to the complexity of plasma turbulence in stellarators. However, with the advent of gyrokinetic codes valid for 3D geometries such as GENE,ootnotetextF. Jenko, W. Dorland, M. Kotschenreuther, B.N. Rogers, Phys. Plasmas 7, 1904 (2000). and stellarator optimization codes such as STELLOPT,ootnotetextA. Reiman, G. Fu, S. Hirshman, L. Ku, et al, Plasma Phys. Control. Fusion 41 B273 (1999). designing stellarators to also reduce turbulent transport has become a realistic possibility. We have been using GENE to characterize the dependence of turbulent transport on stellarator geometry,ootnotetextH.E Mynick, P.A. Xanthopoulos, A.H. Boozer, Phys.Plasmas 16 110702 (2009). and to identify key geometric quantities which control the transport level. From the information obtained from these GENE studies, we are developing proxy functions which approximate the level of turbulent transport one may expect in a machine of a given geometry, and have extended STELLOPT to use these in its cost function, obtaining stellarator configurations with turbulent transport levels substantially lower than those in the original designs.

Mynick, H. E.

2010-11-01

7

A geometric representation scheme suitable for shape optimization  

NASA Technical Reports Server (NTRS)

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.

Tortorelli, Daniel A.

1990-01-01

8

Fine pitch gold ball bonding optimization  

Microsoft Academic Search

Response surface methodology is used to characterize a state-of-the-art wire bonder with a bottleneck capillary for fine pitch bonding. Regression analysis generates mathematical models to plot 3-D charts and contour charts of ball size and ball shear force as a function of wire bond parameters. A procedure is described to use contour charts to optimize bonding parameters. Bonding windows are

W. K. Shu

1993-01-01

9

On Some Geometric Selection and Optimization Problems via Sorted Matrices  

Microsoft Academic Search

In this paper we apply the selection and optimization technique of Fredrickson and Johnson to a number of geometric selection and optimization problems, some of which have previously been solved by parametric search, and provide efficient and simple algorithms. Our technique improves the solutions obtained by parametric search by a log n factor. For example, we apply the technique to

Alex Glozman; Klara Kedem; Gregory Shpitalnik

1995-01-01

10

On some geometric selection and optimization problems via sorted matrices  

Microsoft Academic Search

In this paper we apply the selection and optimization technique of Frederickson and Johnsonto a number of geometric selection and optimization problems, some of which have previouslybeen solved by parametric search, and provide efficient and simple algorithms. Our techniqueimproves the solutions obtained by parametric search by a log n factor. For example, we applythe technique to the two-line center problem,

Alex Glozman; Klara Kedem; Gregory Shpitalnik

1998-01-01

11

Geometric Computational Mechanics and Optimal Control.  

National Technical Information Service (NTIS)

The research performed during this AFOSR grant has extended the basic discrete DMOC (Discrete Mechanics and Optimal Control) framework to derive algorithms for general nonholonomic multi-body systems, with applications to a variety of problems including s...

M. Desbrun M. Kobilarov

2011-01-01

12

Accelerating method of global optimization for signomial geometric programming  

NASA Astrophysics Data System (ADS)

Signomial geometric programming (SGP) has been an interesting problem for many authors recently. Many methods have been provided for finding locally optimal solutions of SGP, but little progress has been made for global optimization of SGP. In this paper we propose a new accelerating method for global optimization algorithm of SGP using a suitable deleting technique. This technique offers a possibility to cut away a large part of the currently investigated region in which the globally optimal solution of SGP does not exist, and can be seen as an accelerating device for global optimization algorithm of SGP problem. Compared with the method of Shen and Zhang [Global optimization of signomial geometric programming using linear relaxation, Appl. Math. Comput. 150 (2004) 99-114], numerical results show that the computational efficiency is improved obviously by using this new technique in the number of iterations, the required saving list length and the execution time of the algorithm.

Shen, Pei-Ping; Li, Xiao-Ai; Jiao, Hong-Wei

2008-04-01

13

Optimal Doping Profile of MOSFETs Using Geometric Programming  

NASA Astrophysics Data System (ADS)

This study employs a novel geometric programming technique to optimize the doping profile of metal semiconductor oxide field effect transistor (MOSFET) subject to specified device characteristics, such as the threshold voltage, the on- and off-state currents and the subthreshold swing. The optimal design of doping profiles for MOSFET devices is for the first time formulated as a geometric programming problem. This special type of optimization problems can be transformed into a convex optimization problem, and therefore can be solved globally and efficiently. For targeting a designed threshold voltage as well as obtaining a high transconductance, the doping distribution of an examined MOSFET device is extracted. Consequently, various constrains of DC characteristics are estimated to obtain the desired doping profile. The approach provides an alternative way to accelerate the design of doping profile process and benefits the manufacturing of MOS devices.

Chen, Ying-Chieh; Li, Yiming

2009-08-01

14

Geometric properties of graph layouts optimized for greedy navigation  

NASA Astrophysics Data System (ADS)

The graph layouts used for complex network studies have been mainly developed to improve visualization. If we interpret the layouts in metric spaces such as Euclidean ones, however, the embedded spatial information can be a valuable cue for various purposes. In this work, we focus on encoding useful navigational information to geometric coordinates of vertices of spatial graphs, which is a reverse problem of harnessing geometric information for better navigation. In other words, the coordinates of the vertices are a map of the topology, not the other way around. We use a recently developed user-centric navigation protocol to explore spatial layouts of complex networks that are optimal for navigation. These layouts are generated with a simple simulated annealing optimization technique. We compare these layouts to others targeted at better visualization and discuss the spatial statistical properties of the optimized layouts for better navigability and its implication.

Lee, Sang Hoon; Holme, Petter

2012-12-01

15

Geometrical H/D isotope effect on hydrogen bonds in charged water clusters.  

PubMed

To investigate the proton/deuteron geometrical isotope effect of positively and negatively charged water complexes, H5O2+ and H3O2-, we have carried out accurate ab initio path integral simulations considering the electron correlation effect. It has been found that the isotope effect on the hydrogen bond is different between these two species in that the oxygen separation becomes shorter in H5O2+ while longer in H3O2- by deuteron substitution. This behavior is ascribed to the change in the quantum effect of hydrogen bonds whether the shared hydrogen is on a single or double well potential surface. PMID:16117507

Tachikawa, Masanori; Shiga, Motoyuki

2005-08-31

16

Dictionary of protein secondary structure: pattern recognition of hydrogen-bonded and geometrical features  

Microsoft Academic Search

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

Wolfgang Kabsch; Christian Sander

1983-01-01

17

Alternative adhesive strategies to optimize bonding to radicular dentin.  

PubMed

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

Bouillaguet, Serge; Bertossa, Bruno; Krejci, Ivo; Wataha, John C; Tay, Franklin R; Pashley, David H

2007-10-01

18

Optimization of ultrasound and bond force to reduce pad stress in thermosonic Cu ball bonding  

Microsoft Academic Search

Ball bonding processes are optimized on Al pads with a 25.4 ¿m diameter Cu wire to obtain maximum average shear strengths of at least 120 MPa. To quantify the direct effect of bond force and ultrasound on the pad stress, ball bonding is performed on test pads with piezoresistive microsensors integrated next to the pad and the real-time ultrasonic signals

A. Shah; M. Mayer; Y. Zhou; J. Persic; J. T. Moon

2009-01-01

19

The geometrical phase transition in non-linear hydrogen bonding systems  

NASA Astrophysics Data System (ADS)

Hydrogen bonding (HB) in a system consisting of A aD d type molecules is studied by two different statistical ways that are demonstrated to be consistent with each other. The free energies of the sol and gel phases in both pregel and postgel regimes are further obtained. It is shown that the sol-gel phase transition in a non-linear HB system is a geometrical phase transition, and for describing this phase transition, the scaling laws satisfied by the moments, the radii of gyration and the gel free energy near the critical point are obtained.

Wang, Hai-Jun; Hong, Xiao-Zhong; Ba, Xin-Wu

2005-09-01

20

Optimizing the Wire-Bonding Process for Copper Ball Bonding, Using classic Experimental Designs  

Microsoft Academic Search

Two classic experimental designs were used to develop the copper ball bonding process. A two-level factorial design was used to screen five process variables simultaneously and determine whether any of them had a significant effect on the process. A four-factor central composite design was used to optimize and map the bonding process window. The efficiency of using designed experiments allowed

MICHAEL SHEAFFER; LEE R. LEVINE; BRIAN SCHLAIN

1987-01-01

21

Self-optimized resonating-valence-bond trial wavefunctions  

NASA Astrophysics Data System (ADS)

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).

Beach, Kevin; Sandvik, Anders

2007-03-01

22

OPTIMIZATION OF GEOMETRIC FORMS FOR URBAN TRANSPORT STOPS  

Microsoft Academic Search

In order to improve the functioning of urban transport it is necessary to increase the efficiency of intermediate stops and organization of municipal transport service. There are two ways of solving problems of developing urban transport: 1) to install special lanes in the streets for urban transport only and 2) to improve the geometric forms of the existing stops arranging

A. Rimkus

1999-01-01

23

Geometric Optimization of Relative Link Lengths for Biomimetic Robotic Fish  

Microsoft Academic Search

This paper focuses on the design of fishlike underwater robots using an optimization approach to choose relative link lengths. Considering both ichthyologic characteristics and mechatronic constraints, the optimal link-length ratios are numerically calculated by an improved constrained cyclic variable method. Comparative results, before and after the optimization, demonstrate the enhanced performance

Junzhi Yu; Long Wang; Min Tan

2007-01-01

24

Integrated multidisciplinary design optimization using discrete sensitivity analysis for geometrically complex aeroelastic configurations  

Microsoft Academic Search

The first two steps in the development of an integrated multidisciplinary design optimization procedure capable of analyzing the nonlinear fluid flow about geometrically complex aeroelastic configurations have been accomplished in the present work. For the first step, a three-dimensional unstructured grid approach to aerodynamic shape sensitivity analysis and design optimization has been developed. The advantage of unstructured grids, when compared

James Charles Newman III

1997-01-01

25

Optimal Concurrent Dimensional and Geometrical Tolerancing based on Evolutionary Algorithms  

Microsoft Academic Search

A general new methodology using evolutionary algorithm viz., Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) and Multi Objective Particle Swarm Optimization (MOPSO) for obtaining optimal tolerance allocation and alternative process selection for mechanical assembly is presented. The problem has a multi-criterion character in which 3 objective functions, 6 constraints and 11 variables are considered. The average fitness membership function method is

K. Sivakumar; C. Balamurugan; S. Ramabalan; S. B. Venkata Raman

2009-01-01

26

Geometrical optimization of a local ballistic magnetic sensor  

NASA Astrophysics Data System (ADS)

We have developed a highly sensitive local magnetic sensor by using a ballistic transport property in a two-dimensional conductor. A semiclassical simulation reveals that the sensitivity increases when the geometry of the sensor and the spatial distribution of the local field are optimized. We have also experimentally demonstrated a clear observation of a magnetization process in a permalloy dot whose size is much smaller than the size of an optimized ballistic magnetic sensor fabricated from a GaAs/AlGaAs two-dimensional electron gas.

Kanda, Yuhsuke; Nomura, Tatsuya; Kimura, Takashi; Hara, Masahiro

2014-04-01

27

Geometric structure-preserving optimal control of a rigid body  

Microsoft Academic Search

In this paper, we study a discrete variational optimal control problem for a rigid body. The cost to be minimized is the external\\u000a torque applied to move the rigid body from an initial condition to a pre-specified terminal condition. Instead of discretizing\\u000a the equations of motion, we use the discrete equations obtained from the discrete Lagrange–d’Alembert principle, a process\\u000a that

Anthony M. Bloch; Islam I. Hussein; Melvin Leok; Amit K. Sanyal

2009-01-01

28

Multi-response Optimization of Geometrical Factors in Bi-layered Tube Hydroforming  

NASA Astrophysics Data System (ADS)

In the last years many researchers were concentrating to develop and design new unconventional metal forming processes. Among such new technologies, tube hydroforming was proved as one of the most promising. Geometries of the tube and die were found to have significant effects on the hydroformed part. Based on the mathematical models, which describe the effect of the geometrical factors on bi-layered tube hydroforming, a multi-response optimization study was proposed in this paper with the aim to achieve different quality objectives for two different criteria. The optimal geometrical factors of bi-layered tube hydroforming combinations were tabulated and discussed.

Alaswad, A.; Olabi, A. G.; Benyounis, K. Y.

2011-01-01

29

Geometrical optimization of organic microlasers for microfluidic chemical sensing  

NASA Astrophysics Data System (ADS)

We report the design, fabrication, and demonstration of a chemical sensor-based on the spectral shift of organic microcavity lasers. The shape of the cavity contour is used as a parameter and is optimized to improve the sensitivity. Analytical and numerical predictions are in good agreement with experiments performed in a microfluidic environment, showing sensitivities of up to 100 nm per refractive index unit for stadium-shaped microlasers on pedestal. Selective sensing of Hg2+ at a concentration down to 200 ppb is then demonstrated with cavities functionalized by ligands that are known to bind mercuric cations.

Lozenko, Sergey; Faye, Djibril; Zhang, Haitao; Lebental, Mélanie; Lautru, Joseph; Zyss, Joseph; Lefevre, Jean-Pierre; Leray, Isabelle

2014-06-01

30

Geometric optimal design of MR damper considering damping force, control energy and time constant  

NASA Astrophysics Data System (ADS)

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.

Nguyen, Q. H.; Choi, S. B.; Kim, K. S.

2009-02-01

31

Structural topology optimization using a genetic algorithm with a morphological geometric representation scheme  

Microsoft Academic Search

This paper describes a versatile methodology for solving topology design optimization problems using a genetic algorithm (GA). The key to its effectiveness is a geometric representation scheme that works by specifying a skeleton which defines the underlying topology\\/connectivity of a structural continuum together with segments of material surrounding the skeleton. The required design variables are encoded in a chromosome which

K. Tai; S. Akhtar

2005-01-01

32

Effects of geometric nonlinearities on the response of optimized box beam structures  

NASA Technical Reports Server (NTRS)

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.

Ragon, S.; Gurdal, Z.

1993-01-01

33

Optimizations and Performance of a Robotics Grasping Algorithm Described in Geometric Algebra  

NASA Astrophysics Data System (ADS)

The usage of Conformal Geometric Algebra leads to algorithms that can be formulated in a very clear and easy to grasp way. But it can also increase the performance of an implementation because of its capabilities to be computed in parallel. In this paper we show how a grasping algorithm for a robotic arm is accelerated using a Conformal Geometric Algebra formulation. The optimized C code is produced by the CGA framework Gaalop automatically. We compare this implementation with a CUDA implementation and an implementation that uses standard vector algebra.

Wörsdörfer, Florian; Stock, Florian; Bayro-Corrochano, Eduardo; Hildenbrand, Dietmar

34

Geometric Factors Affecting Dentin Bonding in Root Canals: A Theoretical Modeling Approach  

Microsoft Academic Search

Cavity configuration factor (C-factor) is the ratio of the bonded surface area in a cavity to the unbonded surface area. In a box-like class I cavity, there may be five times more bonded surface area than the unbonded surface area. During polymerization, the volume of monomers is reduced, which creates sufficient shrinkage stresses to debond the material from dentin, thereby

Franklin R. Tay; Robert J. Loushine; Paul Lambrechts; R. Norman Weller; David H. Pashley

2005-01-01

35

A Wafer-Bonded, Floating Element Shear-Stress Sensor Using a Geometric Moire Optical Transduction Technique  

NASA Technical Reports Server (NTRS)

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.

Horowitz, Stephen; Chen, Tai-An; Chandrasekaran, Venkataraman; Tedjojuwono, Ken; Cattafesta, Louis; Nishida, Toshikazu; Sheplak, Mark

2004-01-01

36

Optimization of bond transducer vibrations using active and semiactive control  

NASA Astrophysics Data System (ADS)

In ultrasonic wire bonding the required vibrations are generated by an ultrasonic transducer driven in its longitudinal mode. Asymmetries lead to additional orthogonal motions, which result in unwanted fluctuating normal forces in the friction contact. In this publication, a novel design of an ultrasonic transducer with control actuators is presented. The parasitic vibrations are damped in an active control and by the semi-active piezoelectric shunt damping with inductance-resistance networks. A Finite-Element model is developed to optimize the dimensions and the placement of the piezoceramics and to tune the electrical networks. Measurements are conducted on a prototype transducer which validate the simulation results.

Neubauer, Marcus; Brökelmann, Michael; Schwarzendahl, Sebastian M.; Hesse, Hans-J.; Wallaschek, Jörg

2012-03-01

37

Research on automatic optimization of ground control points in image geometric rectification based on Voronoi diagram  

NASA Astrophysics Data System (ADS)

With the development of remote sensing satellites, the data quantity of remote sensing image is increasing tremendously, which brings a huge workload to the image geometric rectification through manual ground control point (GCP) selections. GCP database is one of the effective methods to cut down manual operation. The GCP loaded from database is generally redundant, which may result in a rectification slowdown. How to automatically optimize these ground control points is a problem that should be resolved urgently. According to the basic theory of geometric rectification and the principle of GCP selection, this paper deeply comprehends some existing methods about automatic optimization of GCP, and puts forward a new method of automatic optimization of GCP based on voronoi diagram to filter ground control points from the overfull ones without manual subjectivity for better accuracy. The paper is organized as follows: First, it clarifies the basic theory of remote sensing image multinomial geometric rectification and the arithmetic of how to get the GCP error. Second, it particularly introduces the voronoi diagram including its origin, development and characteristics, especially the creating process. Third, considering the deficiencies of existing methods about automatic optimization of GCP, the paper presents the idea of applying voronoi diagram to filter GCP in order to complete automatic optimization. During this process, it advances the conception of single GCP's importance value based on voronoi diagram. Then by integrating the GCP error and GCP's importance value, the paper gives the theory and the flow of automatic optimization of GCPs as well. It also presents an example of the application of this method. In the conclusion, it points out the advantages of automatic optimization of GCP based on the voronoi diagram.

Li, Ying; Cheng, Bo

2009-10-01

38

Process optimization approach in fine pitch Cu wire bonding  

Microsoft Academic Search

With SiO 2 dielectric under aluminum pads, a 60 µm bond pad pitch with 52 um bond pad opening Cu wire bonding process was developed in PBGA Hip 7 PGE wafer technology. The critical factors (wire type, capillary, and bonding parameter) and critical responses (bonded ball diameter, bonded ball height, wire pull, ball shear and number of metal lift\\/peeling and

B. K. Wong; C. C. Yong; P. L. Eu; B. K. Yap

2011-01-01

39

Optimization-based design of plant-friendly multisine signals using geometric discrepancy criteria  

Microsoft Academic Search

System identification is an important means for obtaining dynamical models for process control applications; experimental\\u000a testing represents the most time-consuming step in this task. The design of constrained, “plant-friendly” multisine input\\u000a signals that optimize a geometric discrepancy criterion arising from Weyl’s Theorem is examined in this paper. Such signals\\u000a are meaningful for data-centric estimation methods, where uniform coverage of the

Hans D. Mittelmann; Gautam Pendse; Daniel E. Rivera; Hyunjin Lee

2007-01-01

40

Geometric Optimization of Serial Chain Manipulator Structures for Working Volume and Dexterity  

Microsoft Academic Search

Broadly speaking, the regional structure of a manipulator, which consists of the three inboard joints and their associated members, determines the workspace shape and volume.The orientation structure, which for a six-degrees-of-free dom manipulator consists of the three outboardjoints and members, determines the geometric dexterity or orientation potential of the manipulator. It is possible to determine the optimal dimensions of the

R. Vijaykumar; K. J. Waldron; M. J. Tsai

1986-01-01

41

Optimization of the blade trailing edge geometric parameters for a small scale ORC turbine  

NASA Astrophysics Data System (ADS)

In general, the method proposed by Whitfield and Baines is adopted for the turbine preliminary design. In this design procedure for the turbine blade trailing edge geometry, two assumptions (ideal gas and zero discharge swirl) and two experience values (WR and ?) are used to get the three blade trailing edge geometric parameters: relative exit flow angle ?6, the exit tip radius R6t and hub radius R6h for the purpose of maximizing the rotor total-to-static isentropic efficiency. The method above is established based on the experience and results of testing using air as working fluid, so it does not provide a mathematical optimal solution to instruct the optimization of geometry parameters and consider the real gas effects of the organic, working fluid which must be taken into consideration for the ORC turbine design procedure. In this paper, a new preliminary design and optimization method is established for the purpose of reducing the exit kinetic energy loss to improve the turbine efficiency ?ts, and the blade trailing edge geometric parameters for a small scale ORC turbine with working fluid R123 are optimized based on this method. The mathematical optimal solution to minimize the exit kinetic energy is deduced, which can be used to design and optimize the exit shroud/hub radius and exit blade angle. And then, the influence of blade trailing edge geometric parameters on turbine efficiency ?ts are analysed and the optimal working ranges of these parameters for the equations are recommended in consideration of working fluid R123. This method is used to modify an existing ORC turbine exit kinetic energy loss from 11.7% to 7%, which indicates the effectiveness of the method. However, the internal passage loss increases from 7.9% to 9.4%, so the only way to consider the influence of geometric parameters on internal passage loss is to give the empirical ranges of these parameters, such as the recommended ranges that the value of ? is at 0.3 to 0.4, and the value of ? is at 0.5 to 0.6.

Zhang, L.; Zhuge, W. L.; Peng, J.; Liu, S. J.; Zhang, Y. J.

2013-12-01

42

Implementation and Optimization of miniGMG - a Compact Geometric Multigrid Benchmark  

SciTech Connect

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.

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

43

Integrated temperature microsensors for characterization and optimization of thermosonic ball bonding process  

Microsoft Academic Search

A novel ball bond process optimization method based on the thermal response of an integrated aluminum microsensor is reported. The in situ temperature during ball bonding is measured and analyzed. The ultrasonic period shows distinct stages corresponding to scrubbing of the ball on the pad, intermetallic bond growth, and ball deformation by ultrasonic softening. A peak of the signal indicates

Michael Mayer; Oliver Paul; Daniel Bolliger; Henry Baltes

2000-01-01

44

Design for geometric parameters of PEM fuel cell by integrating computational fluid dynamics code with optimization method  

Microsoft Academic Search

The present study is aimed at optimization of the geometric parameters of the proton exchange membrane (PEM) fuel cells through numerical simulation. The approach is developed by integrating a direct problem solver with an optimizer. A commercial computational fluid dynamics code is used as the direct problem solver, which is used to simulate the three-dimensional mass, momentum and species transport

Chin-Hsiang Cheng; Hung-Hsiang Lin; Guang-Jer Lai

2007-01-01

45

Macronutrient Optimization and Seasonal Diet Mixing in a Large Omnivore, the Grizzly Bear: A Geometric Analysis  

PubMed Central

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.

Coogan, Sean C. P.; Raubenheimer, David; Stenhouse, Gordon B.; Nielsen, Scott E.

2014-01-01

46

Macronutrient optimization and seasonal diet mixing in a large omnivore, the grizzly bear: a geometric analysis.  

PubMed

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

Coogan, Sean C P; Raubenheimer, David; Stenhouse, Gordon B; Nielsen, Scott E

2014-01-01

47

Joining of Silicon Carbide: Diffusion Bond Optimization and Characterization  

NASA Technical Reports Server (NTRS)

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.

Halbig, Michael C.; Singh, Mrityunjay

2008-01-01

48

Towards the geometric optimization of potential field models - A new spatial operator tool and applications  

NASA Astrophysics Data System (ADS)

We present a new method for automated geometric modifications of potential field models. Computational developments and the increasing amount of available potential field data, especially gradient data from the satellite missions, lead to increasingly complex models and integrated modelling tools. Editing of these models becomes more difficult. Our approach presents an optimization tool that is designed to modify vertex-based model geometries (e.g. polygons, polyhedrons, triangulated surfaces) by applying spatial operators to the model that use an adaptive, on-the-fly model discretization. These operators deform the existing model via vertex-dragging, aiming at a minimized misfit between measured and modelled potential field anomaly. The parameters that define the operators are subject to an optimization process. This kind of parametrization provides a means for the reduction of unknowns (dimensionality of the search space), allows a variety of possible modifications and ensures that geometries are not destroyed by crossing polygon lines or punctured planes. We implemented a particle swarm optimization as a global searcher with restart option for the task of finding optimal operator parameters. This approach provides us with an ensemble of model solutions that allows a selection and geologically reasonable interpretations. The applicability of the tool is demonstrated in two 2D case studies that provide models of different extent and with different objectives. The first model is a synthetic salt structure in a horizontally layered background model. Expected geometry modifications are considerably small and localized and the initial models contain rather little information on the intended salt structure. A large scale example is given in the second study. Here, the optimization is applied to a sedimentary basin model that is based on seismic interpretation. With the aim to evaluate the seismically derived model, large scale operators are applied that mainly cause depth adjustments to the model horizons.

Haase, Claudia; Götze, Hans-Jürgen

2014-05-01

49

Cu wire bond parameter optimization on various bond pad metallization and barrier layer material schemes  

Microsoft Academic Search

The use of copper wire for semiconductor package assembly has been gradually gaining acceptance throughout the industry over the last decade. Although copper has several advantages over gold for wire bonding applications, the manufacturing difficulties using copper wire have made high volume, fine pitch copper bonding slow to materialize. In recent years with the spike in gold prices, copper wire

Luke England; Siew Tze Eng; Chris Liew; Hock Heng Lim

2011-01-01

50

Optimization of hydrogen bonds for combined DNA\\/collagen complex  

Microsoft Academic Search

Many natural and biological systems including collagen and DNA polymers are formed by a process of molecular self-assembly. In this paper, we developed two novel structural models and built heterogeneous DNA\\/collagen complexes through a preferable arrangement of multiple hydrogen bonds (H-bonds) between DNA and collagen molecules. The simulation results based on three sets of criteria indicate that one of the

Ramana M. Pidaparti; David V. Svintradze; YingFeng Shan; Hiroki Yokota

2009-01-01

51

Plasma enhanced bonding of polydimethylsiloxane with parylene and its optimization  

NASA Astrophysics Data System (ADS)

Polydimethylsiloxane (PDMS) and parylene are among the most widely used polymers in biomedical and microfluidic applications due to their favorable properties. Due to differences in their chemical structure and fabrication methods, it is difficult to integrate them together on a single microfluidic device. In this paper, we have demonstrated a method to bond patterned PDMS with parylene without the use of high temperature or pressure in a two-step process. The steps include (1) the attachment of cured PDMS surface to parylene using microcontact printing to form a weak bond followed by (2) a plasma exposure of sealed assembly to SF6, N2 and O2 gases, which enhanced the quality of bond by approximately fourfold to 1.4 MPa. We systematically investigated the effect of gas flow rates, chamber pressure, plasma time and power using Taguchi's design of experiment method. Composition of the bond formed in this process was evaluated to understand the mechanism of bond formation. Microfluidic channels fabricated from a PDMS replica and a flat parylene-coated surface, bonded using this method, have been able to withstand burst pressures of up to 146 kPa compared to 35 kPa for PDMS prepolymer microcontact printed assembly.

Rezai, Pouya; Selvaganapathy, P. Ravi; Wohl, Gregory R.

2011-06-01

52

Geometric optimization of an active magnetic regenerative refrigerator via second-law analysis  

NASA Astrophysics Data System (ADS)

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 1.1 mm 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.

Li, Peng; Gong, Maoqiong; Wu, Jianfeng

2008-11-01

53

Development of a sensor integration strategy for robotic application based on geometric optimization  

NASA Astrophysics Data System (ADS)

Sensor fusion is an important technology, which is growing exponentially due to its tremendous application potential. Appropriate fusion technology is needed to be developed specially when a system requires redundant sensors to be used. The more the redundancy in sensors, the more the computational complexity for controlling the system and the more is its intelligence level. This research presents a strategy developed for multiple sensor fusion, based on geometric optimization. Each sensor's uncertainty model has been developed. Using Lagrangian optimization techniques the individual sensor's uncertainty has been fused to reduce the overall uncertainty to generate a consensus among the sensors regarding their acceptable values. Using fission-fusion architecture, the precision level has further been improved. Subsequently, using feed back from the fused sensory information, the net error has further been minimized to any pre assigned value by developing a fusion technique in the differential domain (FDD). The techniques have been illustrated using synthesized data from two types of sensors (optical encoder and a single camera vision sensor). The application experience of the same fusion strategy in improving the precision of correctness of stereo matching using multiple baselines has also been discussed.

Nandi, Gora C.; Mitra, Debjani

2001-03-01

54

Geometric optimization of the 56 MHz SRF cavity and its frequency table  

SciTech Connect

It is essential to know the frequency of a Superconducting Radio Frequency (SRF) cavity at its 'just being fabricated' stage because frequency is the key parameter in constructing the cavity. In this paper, we report our work on assessing it. We can estimate the frequency change from stage to stage theoretically and/or by simulation. At the operating stage, the frequency can be calculated accurately, and, from this value, we obtain the frequencies at other stages. They are listed in a table that serves to check the processes from stage to stage. Equally important is optimizing the geometric shape of the SRF cavity so that the peak electric-field and peak magnetic-field are as low as possible. It is particularly desirable in the 56MHz SRF cavity of RHIC to maximize the frequency sensitivity of the slow tuner. After undertaking such optimization, our resultant peak electric-field is only 44.1MV/m, and the peak magnetic-field is 1049G at 2.5MV of voltage across the cavity gap. To quench superconductivity in an SRF cavity, it is reported that the limit of the peak magnetic-field is 1800G [1], and that of the peak electric-field is more than l00MV/m for a SRF cavity [2]. Our simulations employed the codes Superfish and Microwave Studio.

Chang,X.; Ben-Zvi, I.

2008-10-01

55

A geometrical optimization of a magneto-rheological rotary brake in a prosthetic knee  

NASA Astrophysics Data System (ADS)

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.

Gudmundsson, K. H.; Jonsdottir, F.; Thorsteinsson, F.

2010-03-01

56

Optimization of the Geometric Beta for the SSR2 Cavities of the Project X  

SciTech Connect

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.

Solyak, N.; Vostrikov, A.; Yakovlev, V.P.; /Fermilab; Awida, M.H.; Berrutti, P.; Gonin, I.V.; /Fermilab

2012-05-01

57

Plasma enhanced bonding of polydimethylsiloxane with parylene and its optimization  

Microsoft Academic Search

Polydimethylsiloxane (PDMS) and parylene are among the most widely used polymers in biomedical and microfluidic applications due to their favorable properties. Due to differences in their chemical structure and fabrication methods, it is difficult to integrate them together on a single microfluidic device. In this paper, we have demonstrated a method to bond patterned PDMS with parylene without the use

Pouya Rezai; P. Ravi Selvaganapathy; Gregory R. Wohl

2011-01-01

58

Ball bond process optimization using in situ ball shear force  

Microsoft Academic Search

Increasing I\\/O count on chips requires that wire bonders improve their productivity and cost effectiveness in order to remain a viable chip packaging solution. Increasing I\\/O density has pushed bond pad pitches smaller and smaller. Currently, 45 ?m pitch processes are being qualified for high volume production and 35 ?m pitch pads are on the road map. These fine pitch

J. Medding; M. Mayer

2003-01-01

59

Bonding  

NSDL National Science Digital Library

Bonding Purpose: To review the 3 Types of Bonds and the 4 Intermolecular Forces. Assignment: Answer the following questions on a separate piece of paper: 1) List the 3 types of bonding, give descriptions and one example of each 2) List the 4 intermolecular forces and draw examples of each. Be ...

Cutting, Mrs.

2008-03-08

60

Optimal tubular adhesive-bonded lap joint of the carbon fiber epoxy composite shaft  

Microsoft Academic Search

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

Ki S. Kim; Won T. Kim; Dai G. Lee; Eui J. Jun

1992-01-01

61

Corporate Debt Value, Bond Covenants, and Optimal Capital Structure  

Microsoft Academic Search

This article examines corporate debt values and capital structure in a unified analytical framework. It derives closed-form results for the value of long-term risky debt and yield spreads, and for optimal capital structure, when firm asset value follows a diffusion process with constant volatility. Debt values and optimal leverage are explicitly linked to firm risk, taxes, bankruptcy costs, risk-free interest

Hayne E. Leland

1994-01-01

62

Inter- and intra-chain disulfide bond prediction based on optimal feature selection.  

PubMed

Protein disulfide bond is formed during post-translational modifications, and has been implicated in various physiological and pathological processes. Proper localization of disulfide bonds also facilitates the prediction of protein three-dimensional (3D) structure. However, it is both time-consuming and labor-intensive using conventional experimental approaches to determine disulfide bonds, especially for large-scale data sets. Since there are also some limitations for disulfide bond prediction based on 3D structure features, developing sequence-based, convenient and fast-speed computational methods for both inter- and intra-chain disulfide bond prediction is necessary. In this study, we developed a computational method for both types of disulfide bond prediction based on maximum relevance and minimum redundancy (mRMR) method followed by incremental feature selection (IFS), with nearest neighbor algorithm as its prediction model. Features of sequence conservation, residual disorder, and amino acid factor are used for inter-chain disulfide bond prediction. And in addition to these features, sequential distance between a pair of cysteines is also used for intra-chain disulfide bond prediction. Our approach achieves a prediction accuracy of 0.8702 for inter-chain disulfide bond prediction using 128 features and 0.9219 for intra-chain disulfide bond prediction using 261 features. Analysis of optimal feature set indicated key features and key sites for the disulfide bond formation. Interestingly, comparison of top features between interand intra-chain disulfide bonds revealed the similarities and differences of the mechanisms of forming these two types of disulfide bonds, which might help understand more of the mechanisms and provide clues to further experimental studies in this research field. PMID:22591475

Niu, Shen; Huang, Tao; Feng, Kai-Yan; He, Zhisong; Cui, Weiren; Gu, Lei; Li, Haipeng; Cai, Yu-Dong; Li, Yixue

2013-03-01

63

Geometric and electronic structure of mixed metal-semiconductor clusters from global optimization.-  

NASA Astrophysics Data System (ADS)

In addition to pure metal and semiconductor clusters, hybrid species that contain both types of constituents occur at the metal-semiconductor interface. Thus, clusters of the form Cu(x)Si(y) were detected by mass spectrometry [1]. In this contribution, the geometric and energetic features of Me(m)Si(7-m) (Me=Cu and Li) clusters are discussed. The choice of these systems is motivated by the structural similarity of the pure Si(7), Li(7), and Cu(7) systems which all stabilize in D(5h) symmetry. On the other hand, Li and Cu, representing the alkali group (IA) and the noble metal group (IB) of the periodic system, are expected to display strongly differing behavior when integrated into a Si(n) cluster, resulting in different ground state geometries for the cases Me = Li and Me = Cu. Addressing this problem by means of geometry optimization requires, in view of the large number of possible atomic permutations for Me(m)Si(7-m) with 0 < m < 7, the use of a global search algorithm. Equilibrium geometries are obtained by simulated annealing within the Nose' thermostat frame. It is observed that Cu(m)Si(7-m) clusters with m < 6 tend towards ground state geometries derived from the D(5h) prototype. For Li(m)Si(7-m), the Li(m) subsystem is found to adsorb on the framework of the Si(7-m) dianion. [1] J.J. Scherer, J.B. Pau, C.P. Collier, A. O'Keefe, and R.J. Saykally, J. Chem. Phys. 103, 9187 (1995).

Hagelberg, Frank; Wu, Jianhua

2006-03-01

64

Housediff: a Map-Based Building Change Detection from High Resolution Satellite Imagery Using Geometric Optimization Method  

NASA Astrophysics Data System (ADS)

This paper presents a novel structural image analysis method based on geometric optimization techniques towards automatic building change detection. The aim of this method is to efficiently detect the changes of various buildings such as small houses and houses with complex roof in an urban area from high resolution satellite imagery by comparing with spatial database (maps). The previous research has indicated of the effectiveness of a map-based building change detection approach, and further investigation suggests the following three problems; (1) the large diversity of building types, roof shape, roof materials, illumination condition and shadow, (2) the difficulty of imagery and maps matching which normally leads to considerable position error, (3) the capacity of extracting various types of newly-built buildings. To solve these problems, we propose a new geometric optimization method which consists of the following two steps; (1) the building recognition based on a combinatorial optimization method for optimal building boundary extraction, (2) the newly-built building extraction based on an optimal building hypothesis search method. The experimental results showed that the detection rate was approximately 89% for existing and changed buildings, and approximately 83% for newly-built buildings. These results demonstrate the effectiveness of the proposed geometric optimization methods to integrate bottom-up and top-down analysis. By combining the locally detected image features with consideration of regional contexts from map, our method can achieve highly accurate building change detection in urban area. The method has been applied to a building change detection service named "HouseDiff" and succeeded in assisting users.

Ishimaru, N.; Iwamura, K.; Kagawa, Y.; Hino, T.

2012-07-01

65

An optimization-based method for geometrical calibration in cone-beam CT without dedicated phantoms  

NASA Astrophysics Data System (ADS)

In this paper we present a new method for the determination of geometrical misalignments in cone-beam CT scanners, from the analysis of the projection data of a generic object. No a priori knowledge of the object shape and positioning is required. We show that a cost function, which depends on the misalignment parameters, can be defined using the projection data and that such a cost function has a local minimum in correspondence to the actual parameters of the system. Hence, the calibration of the scanner can be carried out by minimizing the cost function using standard optimization techniques. The method is developed for a particular class of 3D object functions, for which the redundancy of the fan beam sinogram in the transaxial midplane can be extended to cone-beam projection data, even at wide cone angles. The method has an approximated validity for objects which do not belong to that class; in that case, a suitable subset of the projection data can be selected in order to compute the cost function. We show by numerical simulations that our method is capable to determine with high accuracy the most critical misalignment parameters of the scanner, i.e., the transversal shift and the skew of the detector. Additionally, the detector slant can be determined. Other parameters such as the detector tilt, the longitudinal shift and the error in the source-detector distance cannot be determined with our method, as the proposed cost function has a very weak dependence on them. However, due to the negligible influence of these latter parameters in the reconstructed image quality, they can be kept fixed at estimated values in both calibration and reconstruction processes without compromising the final result. A trade-off between computational cost and calibration accuracy must be considered when choosing the data subset used for the computation of the cost function. Results on real data of a mouse femur as obtained with a small animal micro-CT are shown as well, proving the capability of the proposed calibration method. In principle, the method can be adapted to other cone-beam imaging modalities (e.g., single photon emission computed tomography).

Panetta, D.; Belcari, N.; DelGuerra, A.; Moehrs, S.

2008-07-01

66

An optimization-based method for geometrical calibration in cone-beam CT without dedicated phantoms.  

PubMed

In this paper we present a new method for the determination of geometrical misalignments in cone-beam CT scanners, from the analysis of the projection data of a generic object. No a priori knowledge of the object shape and positioning is required. We show that a cost function, which depends on the misalignment parameters, can be defined using the projection data and that such a cost function has a local minimum in correspondence to the actual parameters of the system. Hence, the calibration of the scanner can be carried out by minimizing the cost function using standard optimization techniques. The method is developed for a particular class of 3D object functions, for which the redundancy of the fan beam sinogram in the transaxial midplane can be extended to cone-beam projection data, even at wide cone angles. The method has an approximated validity for objects which do not belong to that class; in that case, a suitable subset of the projection data can be selected in order to compute the cost function. We show by numerical simulations that our method is capable to determine with high accuracy the most critical misalignment parameters of the scanner, i.e., the transversal shift and the skew of the detector. Additionally, the detector slant can be determined. Other parameters such as the detector tilt, the longitudinal shift and the error in the source-detector distance cannot be determined with our method, as the proposed cost function has a very weak dependence on them. However, due to the negligible influence of these latter parameters in the reconstructed image quality, they can be kept fixed at estimated values in both calibration and reconstruction processes without compromising the final result. A trade-off between computational cost and calibration accuracy must be considered when choosing the data subset used for the computation of the cost function. Results on real data of a mouse femur as obtained with a small animal micro-CT are shown as well, proving the capability of the proposed calibration method. In principle, the method can be adapted to other cone-beam imaging modalities (e.g., single photon emission computed tomography). PMID:18583729

Panetta, D; Belcari, N; Del Guerra, A; Moehrs, S

2008-07-21

67

The optimization of the geometric cross-section dimensions of raised pedestrian crosswalks: a case study in Qazvin.  

PubMed

This study attempts to optimize the geometric cross-section dimensions of raised pedestrian crosswalks (RPC), employing safety and comfort measures which reflect environmental conditions and drivers behavioral patterns in Qazvin, Iran. Geometric characteristics including street width, ramp lengths, top flat crown length and height, and 4672 spot speed observations of 23 implemented RPCs were considered. The authors established geometric and analytical equations to satisfactorily express the discomfort that vehicle occupants experience while traversing an RPC and the crossing risk to pedestrians. Artificial neural networks (ANN) are reputed for their capability to learn and generalize complex engineering phenomena and were therefore adopted to cope with the highly nonlinear relationship between the before-RPC spot speeds, the geometric characteristics, and spot speeds on the RPC. This on-RPC spot speed has been utilized for computing the above-mentioned criteria. Combining these criteria, a new judgment index was created to identify the optimum RPC which fulfills the highest comfort and safety levels. It was observed that the variable with the highest impact is the second ramp length, followed by the first ramp length, top flat crown length, before-RPC spot speed, height, and street width, in order of magnitude. PMID:19245891

Mohammadipour, Amir H; Alavi, Seyed Hafez

2009-03-01

68

Optimized Cu-Sn Wafer-Level Bonding Using Intermetallic Phase Characterization  

NASA Astrophysics Data System (ADS)

The objective of this study is to optimize the Cu/Sn solid-liquid interdiffusion process for wafer-level bonding applications. To optimize the temperature profile of the bonding process, the formation of intermetallic compounds (IMCs) which takes place during the bonding process needs to be well understood and characterized. In this study, a simulation model for the development of IMCs and the unreacted remaining Sn thickness as a function of the bonding temperature profile was developed. With this accurate simulation model, we are able to predict the parameters which are critical for bonding process optimization. The initial characterization focuses on a kinetics model of the Cu3Sn thickness growth and the amount of Sn thickness that reacts with Cu to form IMCs. As-plated Cu/Sn samples were annealed using different temperatures (150°C to 300°C) and durations (0 min to 320 min). The kinetics model is then extracted from the measured thickness of IMCs of the annealed samples.

Luu, Thi-Thuy; Duan, Ani; Aasmundtveit, Knut E.; Hoivik, Nils

2013-12-01

69

Collision-induced dissociation of Ni sup + sub n ( n =2--18) with Xe: Bond energies, geometrical structures, and dissociation pathways  

SciTech Connect

The kinetic energy dependence of the collision-induced dissociation (CID) of Ni{sup +}{sub {ital n}} ({ital n}=2--18) with xenon is studied by using a guided ion beam mass spectrometer. Bond energies of nickel cluster ions, {ital D}{sup 0}(Ni{sup +}{sub {ital n}{minus}1}--Ni), are determined from measurements of the CID thresholds. Bond energies for neutral nickel clusters, {ital D}{sup 0}(Ni{sub {ital n}{minus}1}--Ni), are derived by combining these ionic bond energies with literature values of ionization energies for Ni{sub {ital n}}. Both {ital D}{sup 0}(Ni{sup +}{sub {ital n}{minus}1}--Ni) and {ital D}{sup 0}(Ni{sub {ital n}{minus}1}--Ni) are found to increase nonmonotonically as a function of cluster size, with local maxima at {ital n}=3, 7, and 13 for ionic clusters and at {ital n}=6 and 13 for neutral clusters. Examination of the cluster size dependence of nickel cluster bond energies leads to speculations on the likely cluster geometric structures. Examination of the general dissociation behavior over a broad collision energy range shows that nickel cluster ions dissociate primarily by sequential atom loss, although exceptions are noted.

Lian, L.; Su, C.; Armentrout, P.B. (Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States))

1992-05-15

70

Problem of the Optimization of the Geometric Parameters of a Turbine Stage during the Twisting of the Fixed and Moving Blades.  

National Technical Information Service (NTIS)

The perfecting of the flow part of contemporary turbine stages is provided mainly by two methods: the use of vane cascades with great aerodynamic characteristics, and mutual agreement of the geometric parameters of the cascades in order to guarantee optim...

A. Y. Shkvar

1974-01-01

71

Optimization of Stability Constrained Geometrically Nonlinear Shallow Trusses Using an Arc Length Sparse Method with a Strain Energy Density Approach  

NASA Technical Reports Server (NTRS)

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.

Hrinda, Glenn A.; Nguyen, Duc T.

2008-01-01

72

A numerical study on the optimal geometric design of speed control humps  

Microsoft Academic Search

The aim of the present paper is to find an optimum speed control hump geometric design by using the sequential quadratic programming method. Theoretical investigation of the dynamic behavior of the driver body components and the vehicle due to crossing speed control humps is presented. The vehicle–driver system represented as a mathematical model consists of 12 degrees of freedom (DOF).

Emad Khorshid; Mohammed Alfares

2004-01-01

73

Geometric parametrization and constrained optimization techniques in the design of salient pole synchronous machines  

Microsoft Academic Search

The shape optimization of magnetic devices is efficiently performed with field calculation and sensitivity analysis based on the finite element method. Several sequential unconstrained optimization techniques are discussed and evaluated with respect to their application in engineering design. The optimization of the geometry of a salient pole generator so as to achieve a desired field configuration in the airgap is

Konrad Weeber; S. R. H. Hoole

1992-01-01

74

Fluence map optimization (FMO) with dose-volume constraints in IMRT using the geometric distance sorting method.  

PubMed

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. PMID:22996086

Lan, Yihua; Li, Cunhua; Ren, Haozheng; Zhang, Yong; Min, Zhifang

2012-10-21

75

Fluence map optimization (FMO) with dose-volume constraints in IMRT using the geometric distance sorting method  

NASA Astrophysics Data System (ADS)

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.

Lan, Yihua; Li, Cunhua; Ren, Haozheng; Zhang, Yong; Min, Zhifang

2012-10-01

76

Optimizing geometrical design of superhydrophobic surfaces for prevention of microelectromechanical system (MEMS) stiction  

Microsoft Academic Search

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,

Lingbo Zhu; Yonghao Xiu; Jianwen Xu; Dennis W. Hess; C. P. Wong

2006-01-01

77

Optimal allocation of local feedback in multistage amplifiers via geometric programming  

Microsoft Academic Search

We consider the problem of optimally allocating local feedback to the stages of a multistage amplifier. The local feedback gains affect many performance indexes for the overall amplifier, such as bandwidth, gain, rise time, delay, output signal swing, linearity, and noise performance, in a complicated and nonlinear fashion, making optimization of the feedback gains a challenging problem. In this paper,

Joel L. Dawson; Stephen P. Boyd; Maria del Mar Hershenson; Thomas H. Lee

2001-01-01

78

Theoretical analysis of the geometrical isotope effect on the hydrogen bonds in photoactive yellow protein with multi-component density functional theory  

NASA Astrophysics Data System (ADS)

To theoretically analyze the nuclear quantum effects of protons on two hydrogen bonds around the chromophore (CRO) in the photoactive yellow protein (PYP), we have calculated simple cluster model consisting of CRO, Glu46, and Tyr42 residues in PYP with the multi-component molecular orbital method and multi-component density functional theory, which can take account of quantum fluctuations of light mass particles. The average OO distances between CRO and Glu46 and between CRO and Tyr42 with our methods are shorter than the corresponding equilibrium ones, while the OH distances become longer due to the anharmonicity of the potential. The H/D geometrical isotope effect is also found, that is, the distances between oxygen atoms are elongated by the deuterium substitution, known as Ubbelohde effect.

Kita, Yukiumi; Kamikubo, Hironari; Kataoka, Mikio; Tachikawa, Masanori

2013-06-01

79

An optimized face-down bonding process for laser diode packages  

Microsoft Academic Search

We present an optimized face-down die attachment for single-mode ridge-waveguide laser diodes (LDs) using Au80Sn20 solder. Based on this improved technique, a bonding process window has been determined through microstructure and mechanical investigation of the solder joint, and electro-optical characterization of LDs. Metallographical investigation shows that the solder joint comprises of a layer of ? phase near the LD\\/solder and

J. W. R. Tewl; Z. F. Wang; X. Q. Shi; G. Y. Lil

2004-01-01

80

Simultaneous geometrical and material optimal design of hybrid elastomer\\/composite sandwich plates  

Microsoft Academic Search

The paper presents the complete optimization of a hybrid elastomer\\/composite sandwich plate structure: design variables consists in the total number of layers of the structure, their respective thicknesses, their fiber orientation, the position(s) of the viscoelastic core(s) and the stacking sentence. The damping of the hybrid structure is calculated by the Method of Strain Energy (MSE). The constrained optimization maximizes

N. Le Maoût; E. Verron; J. Bégué

81

Geometric existence theory for the control-affine nonlinear optimal regulator  

NASA Astrophysics Data System (ADS)

For infinite horizon nonlinear optimal control problems in which the control term enters linearly in the dynamics and quadratically in the cost, well-known conditions on the linearised problem guarantee existence of a smooth globally optimal feedback solution on a certain region of state space containing the equilibrium point. The method of proof is to demonstrate existence of a stable Lagrangian manifold M and then construct the solution from M in the region where M has a well-defined projection onto state space. We show that the same conditions also guarantee existence of a nonsmooth viscosity solution and globally optimal set-valued feedback on a much larger region. The method of proof is to extend the construction of a solution from M into the region where M no-longer has a well-defined projection onto state space.

McCaffrey, D.; Banks, S. P.

2005-05-01

82

A Single-Lap Joint Adhesive Bonding Optimization Method Using Gradient and Genetic Algorithms  

NASA Technical Reports Server (NTRS)

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.

Smeltzer, Stanley S., III; Finckenor, Jeffrey L.

1999-01-01

83

Orbital Exponent Optimization in Elementary VB Calculations of the Chemical Bond in the Ground State of Simple Molecular Systems  

ERIC Educational Resources Information Center

Orbital exponent optimization in the elementary ab-initio VB calculation of the ground states of H[subscript 2][superscript +], H[subscript 2], He[subscript 2][superscript +], He[subscript 2] gives a fair description of the exchange-overlap component of the interatomic interaction that is important in the bond region. Correct bond lengths and…

Magnasco, Valerio

2008-01-01

84

Geometrical optimization of an annulus Compton suppression system using Monte Carlo simulation.  

PubMed

We are planning to construct a Compton-suppression system permitting accurate and precise determinations of radioactivity of low-level environmental samples. An annulus guard detector (NaI) and a plug-in detector (NaI) are being used as suppression detectors with an HPGe primary detector. The geometry of the Compton suppression spectrometer was optimized by simulation with PENELOPE for obtaining the highest suppression factor (SF) for a point source. The results of the simulations show that the ultimate value of the suppression factor is 7.87 ± 0.18, obtained when the source is located at 57% of an annuls guard detector. PMID:23583087

Han, Jubong; Lee, K B; Park, T S; Lee, J M; Lee, S H

2013-11-01

85

Optimization of geometric characteristics to improve sensing performance of MEMS piezoresistive strain sensors  

NASA Astrophysics Data System (ADS)

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.

Mohammed, Ahmed A. S.; Moussa, Walied A.; Lou, Edmond

2010-01-01

86

Optimal image alignment with random projections of manifolds: algorithm and geometric analysis.  

PubMed

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

Kokiopoulou, Effrosyni; Kressner, Daniel; Frossard, Pascal

2011-06-01

87

Geometric optimization of a step bearing for a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.  

PubMed

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

Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

2013-09-01

88

Optimal tubular adhesive-bonded lap joint of the carbon fiber epoxy composite shaft  

NASA Astrophysics Data System (ADS)

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.

Kim, Ki S.; Kim, Won T.; Lee, Dai G.; Jun, Eui J.

89

The H-bonding network of acylguanidine complexes: combined intermolecular (2h)J(H,P) and (3h)J(N,P) scalar couplings provide an insight into the geometric arrangement.  

PubMed

The H-bonding networks of arginines and acylguanidines are crucial for many biological and pharmaceutical interactions. However, the effect of acylation of guanidines on the binding mode and the H-bond strengths has not yet been explored in solution. Therefore, the H-bonding network of a (15)N labeled acylguanidine derivative in a bisphosphonate arginine receptor is investigated. The direct NMR detection of 1D, 2D, and 3D correlations caused by (2h)J(H,P) and, for the first time in nonbiomacromolecules, (3h)J(N,P) couplings, allows for the geometric analysis of the H-bonding network and indicates an end-on binding mode with two different POH angles. The acylguanidine adopts the same binding mode as the corresponding guanidine but forms significantly stronger H-bonds. This may explain the success of acylguanidine ligands in medicinal chemistry applications. PMID:19053451

Federwisch, Guido; Kleinmaier, Roland; Drettwan, Diana; Gschwind, Ruth M

2008-12-17

90

SHORTEST PATHS FOR THE REEDS-SHEPP CAR: A WORKED OUT EXAMPLE OF THE USE OF GEOMETRIC TECHNIQUES IN NONLINEAR OPTIMAL CONTROL. 1  

Microsoft Academic Search

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

J. Sussmann; Guoqing Tang

1991-01-01

91

A 1 kWel thermoelectric stack for geothermal power generation - Modeling and geometrical optimization  

NASA Astrophysics Data System (ADS)

A thermoelectric stack composed of arrays of Bi-Te alloy thermoelectric converter (TEC) modules is considered for geothermal heat conversion. The TEC modules consist of Al2O3 plates with surface 30×30 mm2 and 127 p-type (Bi0.2Sb0.8)2Te3 and n-type Bi2(Te0.96Se0.04)3 thermoelement pairs, each having a cross-section of 1.05×1.05 mm2, and with a figure-of-merit of 1 and a heat-to-electricity conversion efficiency of ~5%. A heat transfer model is formulated to couple conduction in the thermoelements with convection between the Al2O3 plates and the water flow in counter-flow channel configuration. The calculated open-circuit voltages are compared to those resulting from the mean temperature differences across the TEC modules computed by CFD. The investigated parameters are: hot water inlet and outlet temperatures (373 - 413 K and 323 - 363 K, respectively), stack length (300 - 1500 mm), thermoelement length (1 - 4 mm) and hot channel heights (0.2 - 2 mm). The heat transfer model is then applied to optimize a 1 kWel stack with hot water inlet at 393 K and outlet at 353 K for either maximum heat-to-electricity conversion efficiency of 2.9% or minimum size of 0.0044 m3.

Suter, C.; Jovanovic, Z.; Steinfeld, A.

2012-06-01

92

Determining the optimal PDMS–PDMS bonding technique for microfluidic devices  

Microsoft Academic Search

A number of polydimethysiloxane (PDMS) bonding techniques have been reported in the literature over the last several years as the focus on multilayer PDMS microfluidic devices has increased. Oxygen plasma bonding, despite cost, additional fabrication time and inconsistent bonding results, has remained a widely used method for bonding PDMS layers. A comparative study of four rapid, inexpensive alternative PDMS–PDMS bonding

Mark A Eddings; Michael A Johnson; Bruce K Gale

2008-01-01

93

Optimizing Diffusion Bonding Parameters in AA6061-T6 Aluminum and AZ80 Magnesium Alloy Dissimilar Joints  

NASA Astrophysics Data System (ADS)

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.

Joseph Fernandus, M.; Senthilkumar, T.; Balasubramanian, V.; Rajakumar, S.

2012-11-01

94

Extremal Optimization for Ground States of the Sherrington-Kirkpatrick Spin Glass with Levy Bonds  

NASA Astrophysics Data System (ADS)

Using the Extremal Optimization heuristic (EO),footnotetextS. Boettcher & A.G. Percus, PRL 86, 5211 (2001) ground states of the SK-spin glass are studied with bonds J distributed according to a Levy distribution P(J)1/|J|^1+? with |J|>1 and 1bonds.footnotetextS. Boettcher, Philosophical Magazine 92, 34 (2012) We find that the energies attain universally the Parisi-energy of the SK when the second moment of P(J) exists (?>2). They compare favorably with recent one-step replica symmetry breaking predictions well below ?=2. Near ?=2, the simulations deviate significantly from theoretical expectations. The finite-size corrections exponent ? decays from the putative SK value ?SK=23 already well above ?=2. The exponent ? for the scaling of ground state energy fluctuations with system size decays linearly from its SK value for decreasing ? and vanishes at ?=1.

Boettcher, Stefan

2013-03-01

95

Why is N···Be distance of NH3H(+)···DBeH shorter than that of NH3D(+)···HBeH? Paradoxical geometrical isotope effects for partially isotope-substituted dihydrogen-bonded isotopomers.  

PubMed

The partial isotope substitution for the change of geometrical parameters, interaction energies, and nuclear magnetic shielding tensors (?) of dihydrogen-bonded NH3X(+)···YBeH (X, Y?=?H, D, and T) systems is analyzed. Based on the theoretical calculation, the distance between heavy atoms RN···Be of NH3H(+) ···DBeH is clearly found to be shorter than that in NH3D(+)···HBeH. Such apparently paradoxical geometrical isotope effect (GIE) on RN···Be is revealed by the cooperative effect of two kinds of (1) primary covalent-bonded GIE and (2) secondary dihydrogen-bonded one. We have demonstrated that (1) the covalent bond lengths become shorter by heavier isotope-substitution and (2) the dihydrogen-bonded distance RX···Y becomes shorter by heavier Y and lighter X isotope-substitution due to the difference of electronic structure reflected by the nuclear distribution. We have also found that interaction energy of NH3H(+)···DBeH is stronger than that of NH3D(+)···HBeH and isotopic deshielding effect of magnetic shielding becomes large in lighter isotope. PMID:24323845

Udagawa, Taro; Tachikawa, Masanori

2014-02-01

96

Optimization of the Cu wire bonding process for IC assembly using Taguchi methods  

Microsoft Academic Search

The yield of IC assembly manufacturing is dependent on wire bonding. Recently, the semiconductor industry demands smaller IC designs and higher performance requirements. As such, bonding wires must be stronger, finer, and more solid. The cost of gold is continuously appreciating, and this has become a key issue in IC assembly and design. Copper wire bonding is an alternative solution

Chao-Ton Su; Cheng-Jung Yeh

2011-01-01

97

Anatomy-based inverse optimization in high-dose-rate brachytherapy combined with hypofractionated external beam radiotherapy for localized prostate cancer: Comparison of incidence of acute genitourinary toxicity between anatomy-based inverse optimization and geometric optimization  

SciTech Connect

Purpose: To evaluate the advantages of anatomy-based inverse optimization (IO) in planning high-dose-rate (HDR) brachytherapy. Methods and Materials: A total of 114 patients who received HDR brachytherapy (9 Gy in two fractions) combined with hypofractionated external beam radiotherapy (EBRT) were analyzed. The dose distributions of HDR brachytherapy were optimized using geometric optimization (GO) in 70 patients and by anatomy-based IO in the remaining 44 patients. The correlation between the dose-volume histogram parameters, including the urethral dose and the incidence of acute genitourinary (GU) toxicity, was evaluated. Results: The averaged values of the percentage of volume receiving 80-150% of the prescribed minimal peripheral dose (V{sub 8}-V{sub 15}) of the urethra generated by anatomy-based IO were significantly lower than the corresponding values generated by GO. Similarly, the averaged values of the minimal dose received by 5-50% of the target volume (D{sub 5}-D{sub 5}) obtained using anatomy-based IO were significantly lower than those obtained using GO. Regarding acute toxicity, Grade 2 or worse acute GU toxicity developed in 23% of all patients, but was significantly lower in patients for whom anatomy-based IO (16%) was used than in those for whom GO was used (37%), consistent with the reduced urethral dose (p <0.01). Conclusion: The results of this study suggest that anatomy-based IO is superior to GO for dose optimization in HDR brachytherapy for prostate cancer.

Akimoto, Tetsuo [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan)]. E-mail: takimoto@showa.gunma-u.ac.jp; Katoh, Hiroyuki [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Kitamoto, Yoshizumi [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Shirai, Katsuyuki [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Shioya, Mariko [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Nakano, Takashi [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan)

2006-04-01

98

An integrated system for setting the optimal parameters in IC chip-package wire bonding processes  

Microsoft Academic Search

The wire bonding process is the key process in an IC chip-package. It is an urgent problem for IC chip-package industry to\\u000a improve the wire bonding process capability. In this study, an integrated system is proposed to identify and control parameters\\u000a in the wire bonding process in order to achieve high level performance and quality. First, an experimental design with

Tung-Hsu Hou; Shyh-Huei Chen; Tzu-Yu Lin; Kun-Ming Huang

2006-01-01

99

Optimal Trading and Tax Option Value of Defaultable Bonds with Asymmetric Capital Gain Taxes  

Microsoft Academic Search

Abstract Current U.S. tax laws provide investors an incentive to time the sales of their bonds to minimize,tax liability. T his gives rise to a tax timing option that affects bond value. I n reality, corporate bond investors’ tax-timing strategy is complicated by risk of default. E xisting term structure models have ignored the effect of the,tax-timing option and how,much,corporate

Peter Huaiyu Chen; Sheen X. Liu; Chunchi Wu

100

ROBUSTNESS OF OPTIMAL DESIGN SOLUTIONS TO REDUCE VIBRATION TRANSMISSION IN A LIGHTWEIGHT 2-D STRUCTURE, PART I: GEOMETRIC DESIGN  

Microsoft Academic Search

A two-dimensional lightweight cantilever structure is studied, comprising 40 rigidly joined beams, of which the geometry is optimized to reduce vibration transmission over a given bandwidth. In this paper, the optimization is achieved by using genetic algorithms. Ten optimized design candidates were achieved for each of three cases resulting from minimizing an objective function (the vibration transmission between two points

D. K. ANTHONY; S. J. ELLIOTT; A. J. KEANE

2000-01-01

101

Robustness of Optimal Design Solutions to Reduce Vibration Transmission in a Lightweight 2-D Structure, Part i: Geometric Design  

Microsoft Academic Search

A two-dimensional lightweight cantilever structure is studied, comprising 40 rigidly joined beams, of which the geometry is optimized to reduce vibration transmission over a given bandwidth. In this paper, the optimization is achieved by using genetic algorithms. Ten optimized design candidates were achieved for each of three cases resulting from minimizing an objective function (the vibration transmission between two points

D. K. Anthony; S. J. Elliott; A. J. Keane

2000-01-01

102

NMR studies of solvent-assisted proton transfer in a biologically relevant Schiff base: toward a distinction of geometric and equilibrium H-bond isotope effects.  

PubMed

The tautomeric equilibrium in a Schiff base, N-(3,5-dibromosalicylidene)-methylamine 1, a model for the hydrogen bonded structure of the cofactor pyridoxal-5'-phosphate PLP which is located in the active site of the enzyme, was measured by means of 1H and 15N NMR and deuterium isotope effects on 15N chemical shifts at variable temperature and in different organic solvents. The position of the equilibrium was estimated using the one-bond 1J(OHN) and vicinal 3J(H(alpha)CNH) scalar coupling constants. Additionally, DFT calculations of a series of Schiff bases, N-(R1-salicylidene)-alkyl(R2)amines, were performed to obtain the hydrogen bond geometries. The latter made it possible to investigate a broad range of equilibrium positions. The increase of the polarity of the aprotic solvent shifts the proton in the intramolecular OHN hydrogen bond closer to the nitrogen. The addition of methanol and of hexafluoro-2-propanol to 1 in aprotic solvents models the PLP-water interaction in the enzymatic active site. The alcohols, which vary in acidity and change the polarity around the hydrogen bond, also stabilize the equilibrium, so that the proton is shifted to the nitrogen. PMID:16522119

Sharif, Shasad; Denisov, Gleb S; Toney, Michael D; Limbach, Hans-Heinrich

2006-03-15

103

Optimized conditions for imaging the effects of bonding charge density in electron microscopy.  

PubMed

We report on the observability of valence bonding effects in aberration-corrected high resolution electron microscopy (HREM) images along the [010] projection of the mineral Forsterite (Mg?SiO?). We have also performed exit wave restorations using simulated noisy images and have determined that both the intensities of individual images and the modulus of the restored complex exit wave are most sensitive to bonding effects at a level of 25% for moderately thick samples of 20-25 nm. This relatively large thickness is due to dynamical amplification of bonding contrast arising from partial de-channeling of 1s states. Simulations also suggest that bonding contrast is similarly high for an un-corrected conventional electron microscope, implying an experimental limitation of signal to noise ratio rather than spatial resolution. PMID:21193268

Ciston, J; Kim, J S; Haigh, S J; Kirkland, A I; Marks, L D

2011-06-01

104

Optimal specimen geometry in bonded-disk shrinkage-strain measurements on light-cured biomaterials  

Microsoft Academic Search

Objectives: The aim was to determine the effect on apparent shrinkage-strain values of varying specimen aspect ratio in the bonded-disk configuration. Thereby one source of possible inter-laboratory variation might be understood and eliminated.Methods: The bonded-disk procedure was followed and applied to three representative resin-composites. However, specimen sub-groups were examined, each of different diameters (3.5, 5.0, 7.0 and 9.0mm), corresponding to

D. C Watts; A. S Marouf

2000-01-01

105

Optimization of direct currents to enhance dentine bonding of simplified one-step adhesive.  

PubMed

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

Chen, Hongfei; Fu, Dongjie; Yang, Hongye; Liu, Yinchen; Huang, Yanyu; Huang, Cui

2014-08-01

106

A Probabilistic Approach to the Air Traffic Management in The Next Generation Air Transportation System: Optimal Routing Decision With Geometric Recourse Model  

NASA Astrophysics Data System (ADS)

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.

Yoon, Yoonjin

107

Kirkendall voiding in au ball bond interconnects on al chip metallization in the temperature range from 100 – 200°c after optimized intermetallic coverage  

Microsoft Academic Search

The presentation addresses the reliability of Au ball bonds of different Au wire qualities on Al chip metallizations of different thicknesses and compositions at temperature storage from 100 to 200degC up to 4000 h. In this context the interfacial reactions and intermetallic phase coverage directly after the bonding process was optimized to get the best starting condition for phase growth

M. Schneider-Ramelow; S. Schmitz; B. Schuch; W. Grubl

2009-01-01

108

Geometric Additions +Logarithms = Geometric Multiplication  

NSDL National Science Digital Library

Mathematicians often argue that anything which can be represented numerically or algebraically can also be represented geometrically. This is perhaps true even to the extent that simple numeric calculations can be demonstrated geometrically. This example illustrates one such geometric process of addition. This resource is from PUMAS - Practical Uses of Math and Science - a collection of brief examples created by scientists and engineers showing how math and science topics taught in K-12 classes have real world applications.

109

Collision-induced dissociation of Fe sub n sup + ( n =2--19) with Xe: Bond energies, geometric structures, and dissociation pathways  

SciTech Connect

The kinetic energy dependence of the collision-induced dissociation (CID) of Fe{sup +}{sub {ital n}} ({ital n}=11--19) with Xe is studied by using a guided ion beam mass spectrometer. As previously reported for smaller iron cluster ions, these iron cluster ions dissociate exclusively by evaporation, the sequential loss of Fe atoms. Bond energies for the larger iron cluster ions {ital D}{sup 0}(Fe{sup +}{sub {ital n}{minus}1}--Fe), {ital n}=11--19, as well as updated values for the smaller cluster ions, {ital n}=2--10, are reported. These energies are derived after explicit consideration of the effect of secondary collisions between Fe{sup +}{sub {ital n}} and Xe, and of the lifetimes of the energized iron cluster ions. Bond energies for neutral iron clusters are derived by combining these ionic bond energies with literature ionization energies for Fe{sub {ital n}}. Except for the dimers, we find that the bond energies of ionic and neutral iron clusters are very similar and change nonmonotonically as a function of cluster size, with local maxima at {ital n}=6, 7, 13, 15, and 19; and local minima at {ital n}=8, 14, and 18. Evidence for the existence of weakly bound isomers of iron cluster ions is also observed.

Lian, L.; Su, C.; Armentrout, P.B. (Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States))

1992-09-15

110

Geometric Solids  

NSDL National Science Digital Library

This math activity exposes early learners to a variety of three-dimensional objects. Learners bring geometric solids (everyday objects) from home. Learners sort and graph the objects on a Floor Graphing Mat. After the activity, learners can explore the geometric shapes in centers (see Extensions).

Lessonplans, Utah

2012-09-18

111

Optimizing dentin bond durability: strategies to prevent hydrolytic degradation of the hybrid layer  

PubMed Central

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.

Tjaderhane, 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

112

Optimized Tersoff potential parameters for tetrahedrally bonded III-V semiconductors  

Microsoft Academic Search

We address the issue of accurate parametrization for the Abell-Tersoff empirical potential applied to tetra- hedrally bonded semiconductor materials. Empirical potential methods for structural relaxation are widely used for group IV semiconductors while, with few notable exceptions, work on III-V materials has not been extensive. In the case of the Abell-Tersoff potential parametrizations exist only for III-As and III-N, and

D. Powell; M. A. Migliorato; A. G. Cullis

2007-01-01

113

Rational introduction of disulfide bond to enhance optimal temperature of Lipomyces starkeyi alpha-dextranase expressed in Pichia pastoris.  

PubMed

Alpha-dextranase, which can hydrolyze dextran, is largely used in the sugar industry. However, a thermostable alpha- dextranase is needed to alleviate the viscosity of syrups and clean blocked machines. Thus, to improve the optimal temperature of Lipomyces starkeyi alpha-dextranase expressed by Pichia pastoris, the rational introduction of a de novo designed disulfide bond was investigated. Based on the known structure of Penicillium minioluteum dextranase, L. starkeyi alpha-dextranase was constructed using homology modeling. Four amino acids residues were then selected for site-directed mutagenesis to cysteine. When compared with the wildtype dextranase, the mutant DexM2 (D279C/S289C) showed a more than 13oC improvement on its optimal temperature. DexM2 and DexM12 (T245C/N248C, D279C/S289C) also showed a better thermal stability than the wild-type dextranase. After the introduction of two disulfide bonds, the specific activity of DexM12 was evaluated and found to be two times higher than that of the wild-type. Moreover, DexM12 also showed the highest Vmax. PMID:20075611

Chen, Lin; Yu, Chao; Zhou, Xiangshan; Zhang, Yuanxing

2009-12-01

114

Geometric and Electronic Structure of [{Cu(MeAN)}2(?-?2:?2(O22?))]2+ with an Unusually Long O-O Bond: O-O Bond Weakening vs Activation for Reductive Cleavage  

PubMed Central

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.

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

115

Collision-induced dissociation of Ti sup + sub n ( n =2--22) with Xe: Bond energies, geometric structures, and dissociation pathways  

SciTech Connect

The kinetic energy dependence of the collision-induced dissociation (CID) of Ti{sup +}{sub {ital n}} ({ital n}=2--22) with Xe is studied by using a guided ion beam mass spectrometer. Examination of the CID cross section behavior over a broad collision energy range demonstrates that Ti{sup +}{sub {ital n}} clusters dissociate exclusively by sequential loss of Ti atoms. Bond energies of ionic titanium clusters, {ital D}{sup 0}(Ti{sup +}{sub {ital n}{minus}1}--Ti), are determined from measurements of the CID thresholds. {ital D}{sup 0}(Ti{sup +}{sub {ital n}{minus}1}--Ti) are found to change significantly as a function of cluster size, with local maxima at {ital n}=7, 13, and 19. This pattern of highly stable cluster ions suggests that titanium cluster ions favor icosahedral structures.

Lian, L.; Su, C.; Armentrout, P.B. (Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States))

1992-09-15

116

Geometrical optimization of the transmission and dispersion properties of arrayed waveguide gratings using two stigmatic point mountings  

NASA Astrophysics Data System (ADS)

In this paper, the procedure to optimize flat-top Arrayed Waveguide Grating (AWG) devices in terms of transmission and dispersion properties is presented. The systematic procedure consists on the stigmatization and minimization of the Light Path Function (LPF) used in classic planar spectrograph theory. The resulting geometry arrangement for the Arrayed Waveguides (AW) and the Output Waveguides (OW) is not the classical Rowland mounting, but an arbitrary geometry arrangement. Simulation using previous published enhanced modeling show how this geometry reduces the passband ripple, asymmetry and dispersion, in a design example.

Muñoz, P.; Pastor, D.; Capmany, J.; Martínez, A.

2003-09-01

117

Preliminary Simulations for Geometric Optimization of a High-Energy Delayed Gamma Spectrometer for Direct Assay of Pu in Spent Nuclear Fuel  

SciTech Connect

High-energy, beta-delayed gamma-ray spectroscopy is under investigation as part of the Next Generation Safeguard Initiative effort to develop non-destructive assay instruments for plutonium mass quantification in spent nuclear fuel assemblies. Results obtained to date indicate that individual isotope-specific signatures contained in the delayed gamma-ray spectra can potentially be used to quantify the total fissile content and individual weight fractions of fissile and fertile nuclides present in spent fuel. Adequate assay precision for inventory analysis can be obtained using a neutron generator of sufficient strength and currently available detection technology. In an attempt to optimize the geometric configuration and material composition for a delayed gamma measurement on spent fuel, the current study applies MCNPX, a Monte Carlo radiation transport code, in order to obtain the best signal-to-noise ratio. Results are presented for optimizing the neutron spectrum tailoring material, geometries to maximize thermal or fast fissions from a given neutron source, and detector location to allow an acceptable delayed gamma-ray signal while achieving a reasonable detector lifetime while operating in a high-energy neutron field. This work is supported in part by the Next Generation Safeguards Initiative, Office of Nuclear Safeguards and Security, National Nuclear Security Administration.

Kulisek, Jonathan A.; Campbell, Luke W.; Rodriguez, Douglas C.

2012-06-07

118

Optimization of armour geometry and bonding techniques for tungsten-armoured high heat flux components  

Microsoft Academic Search

Joining of tungsten with copper-based cooling structure and armour geometry optimization are the major aspects in development of the tungsten-armoured plasma facing components (PFC). Fabrication techniques and high heat flux (HHF) tests of tungsten-armoured components have to reflect different PFC designs and acceptable manufacturing cost. The authors present the recent results of tungsten-armoured mock-ups development based on manufacturing and HHF

R. N Giniyatulin; V. L Komarov; E. G Kuzmin; A. N Makhankov; I. V Mazul; N. A Yablokov; A. N Zhuk

2002-01-01

119

Geometric Mechanics  

NASA Astrophysics Data System (ADS)

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.

Talman, Richard

1999-10-01

120

Geometric Approach  

Microsoft Academic Search

An automatic cortical gray matter segmentation from a three-dimensional brain images (MR or CT) is a well known problem in medical image processing. In this paper we first formulate it as a geometric variational problem for propagation of two coupled bounding surfaces. An efficient numerical scheme is then used to implement the geodesic active surface model. Exper- imental results of

Roman Goldenberg; Ron Kimmel; Ehud Rivlin; Michael Rudzsky

121

Optimizing an SEM-based 3D surface imaging technique for recording bond coat surface geometry in thermal barrier coatings  

NASA Astrophysics Data System (ADS)

Creation of three-dimensional representations of surfaces from images taken at two or more view angles is a well-established technique applied to optical images and is frequently used in combination with scanning electron microscopy (SEM). The present work describes specific steps taken to optimize and enhance the repeatability of three-dimensional surfaces reconstructed from SEM images. The presented steps result in an approximately tenfold improvement in the repeatability of the surface reconstruction compared to more standard techniques. The enhanced techniques presented can be used with any SEM friendly samples. In this work the modified technique was developed in order to accurately quantify surface geometry changes in metallic bond coats used with thermal barrier coatings (TBCs) to provide improved turbine hot part durability. Bond coat surfaces are quite rough, and accurate determination of surface geometry change (rumpling) requires excellent repeatability. Rumpling is an important contributor to TBC failure, and accurate quantification of rumpling is important to better understanding of the failure behavior of TBCs.

Shahbazmohamadi, Sina; Jordan, Eric H.

2012-12-01

122

Geometric Models  

NSDL National Science Digital Library

Created by Kyle Siegrist of the University of Alabama-Huntsville, this is an online, interactive lesson on geometric models. The author provides examples, exercises, and applets which include Buffon's problems, Bertrand's paradox, and random triangles. Additionally, the author provides links to external resources for students wanting to engage further in this topic. This is simply one lesson in a series of seventeen. They are all easily accessible as the author has formated his site much like an online textbook.

Siegrist, Kyle

2009-02-23

123

Influence of optimized leading-edge deflection and geometric anhedral on the low-speed aerodynamic characteristics of a low-aspect-ratio highly swept arrow-wing configuration. [langley 7 by 10 foot tunnel  

NASA Technical Reports Server (NTRS)

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.

Coe, P. L., Jr.; Huffman, J. K.

1979-01-01

124

Disorder-order structural transformation in electron-poor Sr3Au8Sn3 driven by chemical bonding optimization.  

PubMed

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

Lin, Qisheng; Vetter, Jordan; Corbett, John D

2013-06-01

125

Chemical Distribution and Bonding of Lithium in Intercalated Graphite: Identification with Optimized Electron Energy Loss Spectroscopy  

SciTech Connect

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

126

Comparison of insect kinin analogs with cis-peptide bond motif 4-aminopyroglutamate identifies optimal stereochemistry for diuretic activity.  

PubMed

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, demonstrate significant activity in a cricket diuretic assay. Insect kinin analogs containing (2R,4R)-APy, (2S,4R)-APy and (2S,4S)-APy are essentially equipotent on an insect diuretic assay, with EC(50) values of about 10(-7)M, whereas the (2R,4S)-APy analog is at least 10-fold more potent (EC(50) = 7 x 10(-9)M). Conformational studies in aqueous solution indicate that the (2R,4S)-APy analog is considerably more flexible than the other three variants, which may explain its greater potency. The work identifies the optimal stereochemistry for the APy scaffold with which to design biostable, peptidomimetic analogs with the potential to disrupt critical insect kinin-regulated processes in insects. PMID:17054115

Kaczmarek, Krzysztof; Williams, Howard J; Coast, Geoffrey M; Scott, A Ian; Zabrocki, Janusz; Nachman, Ronald J

2007-01-01

127

Direct bonding and beyond  

NASA Astrophysics Data System (ADS)

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.

Haisma, Jan; Hattu, Nico; (Dook) Pulles, J. T. C. M.; Steding, Esther; Vervest, Jan C. G.

2007-09-01

128

Selective bond breaking mediated by state specific vibrational excitation in model HOD molecule through optimized femtosecond IR pulse: A simulated annealing based approach  

NASA Astrophysics Data System (ADS)

The selective control of O-H/O-D bond dissociation in reduced dimensionality model of HOD molecule has been explored through IR+UV femtosecond pulses. The IR pulse has been optimized using simulated annealing stochastic approach to maximize population of a desired low quanta vibrational state. Since those vibrational wavefunctions of the ground electronic states are preferentially localized either along the O-H or O-D mode, the femtosecond UV pulse is used only to transfer vibrationally excited molecule to the repulsive upper surface to cleave specific bond, O-H or O-D. While transferring from the ground electronic state to the repulsive one, the optimization of the UV pulse is not necessarily required except specific case. The results so obtained are analyzed with respect to time integrated flux along with contours of time evolution of probability density on excited potential energy surface. After preferential excitation from |0, 0> (|m, n> stands for the state having m and n quanta of excitations in O-H and O-D mode, respectively) vibrational level of the ground electronic state to its specific low quanta vibrational state (|1, 0> or |0, 1> or |2, 0> or |0, 2>) by using optimized IR pulse, the dissociation of O-D or O-H bond through the excited potential energy surface by UV laser pulse appears quite high namely, 88% (O-H ; |1, 0>) or 58% (O-D ; |0, 1>) or 85% (O-H ; |2, 0>) or 59% (O-D ; |0, 2>). Such selectivity of the bond breaking by UV pulse (if required, optimized) together with optimized IR one is encouraging compared to the normal pulses.

Shandilya, Bhavesh K.; Sen, Shrabani; Sahoo, Tapas; Talukder, Srijeeta; Chaudhury, Pinaki; Adhikari, Satrajit

2013-07-01

129

Geometrized Gravitation Theories.  

National Technical Information Service (NTIS)

General properties of the geometrized gravitation theories have been considered. Geometrization of the theory is realized only to the extent that by necessity follows from an experiment (geometrization of the density of the matter Lagrangian only). For a ...

A. A. Logunov V. N. Folomeshkin

1977-01-01

130

Exploitation of spatiotemporal information and geometric optimization of signal\\/noise performance using arrays of carbon black-polymer composite vapor detectors  

Microsoft Academic Search

We have investigated various aspects of the geometric and spatiotemporal response properties of an array of sorption-based vapor detectors. The detectors of specific interest are composites of insulating organic polymers filled with electrical conductors, wherein the detector film provides a reversible dc electrical resistance change upon the sorption of an analyte vapor. An analytical expression derived for the signal\\/noise performance

Shawn M. Briglin; Michael S. Freund; Phil Tokumaru; Nathan S. Lewis

2002-01-01

131

Visualizing the Geometric Series.  

ERIC Educational Resources Information Center

Mathematical proofs often leave students unconvinced or without understanding of what has been proved, because they provide no visual-geometric representation. Presented are geometric models for the finite geometric series when r is a whole number, and the infinite geometric series when r is the reciprocal of a whole number. (MNS)

Bennett, Albert B., Jr.

1989-01-01

132

Low-temperature bonding for microdevices  

Microsoft Academic Search

A low-temperature bonding process for packaging surface acoustic wave (SAW) and lead zirconate titanate (PZT) microdevices was developed by the surface activated bonding (SAB) method from room temperature to 100°C. An intermediate gold layer was used in the bonding. The required bonding pressure was optimized. To compare this method with conventional thermocompression bonding and thermosonic bonding methods, die shear and

Ying-Hui Wang; Jian Lu; Tadatomo SUGA

2010-01-01

133

On the efficiency of VBSCF algorithms, a comment on "An efficient algorithm for energy gradients and orbital optimization in valence bond theory".  

PubMed

We comment on the paper [Song et al., J. Comput. Chem. 2009, 30, 399]. and discuss the efficiency of the orbital optimization and gradient evaluation in the Valence Bond Self Consistent Field (VBSCF) method. We note that Song et al. neglect to properly reference Broer et al., who published an algorithm [Broer and Nieuwpoort, Theor. Chim. Acta 1988, 73, 405] to use a Fock matrix to compute a matrix element between two different determinants, which can be used for an orbital optimization. Further, Song et al. publish a misleading comparison with our VBSCF algorithm [Dijkstra and van Lenthe, J. Chem. Phys. 2000, 113, 2100; van Lenthe et al., Mol. Phys. 1991, 73, 1159] to enable them to favorably compare their algorithm with ours. We give detail timings in terms of different orbital types in the calculation and actual timings for the example cases. PMID:22278948

van Lenthe, J H; Broer-Braam, H B; Rashid, Z

2012-03-30

134

Theory of chemical bonds in metalloenzymes XI: Full geometry optimization and vibration analysis of porphyrin iron-oxo species  

NASA Astrophysics Data System (ADS)

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.

Shoji, Mitsuo; Isobe, Hiroshi; Saito, Toru; Kitagawa, Yasutaka; Yamanaka, Shusuke; Kawakami, Takashi; Okumura, Mitsutaka; Yamaguchi, Kizashi

135

Optimal acidulated phosphate fluoride gel etching time for surface treatment of feldspathic porcelain: on shear bond strength to resin composite  

PubMed Central

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.

Kukiattrakoon, Boonlert; Thammasitboon, Kewalin

2012-01-01

136

A tutorial on geometric programming  

Microsoft Academic Search

A geometric program (GP) is a type of mathematical optimization problem characterized by objective and constraint functions\\u000a that have a special form. Recently developed solution methods can solve even large-scale GPs extremely efficiently and reliably;\\u000a at the same time a number of practical problems, particularly in circuit design, have been found to be equivalent to (or well\\u000a approximated by) GPs.

Stephen P. Boyd; Seung-Jean Kim; Lieven Vandenberghe; Arash Hassibi

2007-01-01

137

Parser for signomial and geometric programs  

US Patent & Trademark Office Database

A method and apparatus for parsing signomial and geometric programs, referred to herein as "the Parser". Signomial and Geometric programming is a unique class of mathematical problems that is useful in the study of optimization problems. The Parser is a program designed to recognize and parse both signomial and geometric programs such that they may be accepted and solved by signomial and geometric program solvers. The Parser accepts an optimization problem from a user in the form of algebraic expressions. The Parser can then identify the problem as a signomial program and can further determine if it reduces to a geometric program. If either a signomial or geometric program exists, the Parser converts the algebraic expressions to a compact numeric format that can be accepted by a computer-aided solver. In the case of a geometric program, the solver may find a global solution to the optimization problem. However, in the case of signomial program, the solver may only find a local solution. The solution found by the solver is routed back to the Parser which reports it in a user-readable format.

2007-11-20

138

Fast and optimal solution to the 'Rankine-Hugoniot problem'. [for geometrical shock wave properties, conservation constants and self-consistent asymptotic magnetofluid variables of interplanetary medium  

NASA Technical Reports Server (NTRS)

A new, definitive, reliable and fast iterative method is described for determining the geometrical properties of a shock (i.e., theta sub Bn, yields N, V sub s and M sub A), the conservation constants and the self-consistent asymptotic magnetofluid variables, that uses the three dimensional magnetic field and plasma observations. The method is well conditioned and reliable at all theta sub Bn angles regardless of the shock strength or geometry. Explicit proof of uniqueness of the shock geometry solution by either analytical or graphical methods is given. The method is applied to synthetic and real shocks, including a bow shock event and the results are then compared with those determined by preaveraging methods and other iterative schemes. A complete analysis of the confidence region and error bounds of the solution is also presented.

Vinas, A. F.; Scudder, J. D.

1986-01-01

139

Effect of Geometric Distance on Agreement Dynamics of Naming Game  

NASA Astrophysics Data System (ADS)

We investigate the naming game on geometric networks. The geometric networks are constructed by adding geometric links to two-dimensional regular lattices. It is found that the agreement time is a non-monotonic function of the geometric distance and there exists an optimal value of the geometric distance resulting in the shortest agreement time. All these results show that the geometric distance plays an important role in the evolutionary process of the language game. Our results also show that the convergence time strongly depends on the number of adding links.

Hao, Jia-Bo; Yang, Han-Xin; Liu, Run-Ran; Wang, Bing-Hong; Zhang, Zhi-Yuan

2010-09-01

140

Geometric representations of graphs  

Microsoft Academic Search

The study of geometrically defined graphs, and of the reverse ques- tion, the construction of geometric representations of graphs, leads to unexpected connections between geometry and graph theory. We survey the surprisingly large variety of graph properties related to ge- ometric representations, construction methods for geometric represen- tations, and their applications in proofs and algorithms.

Laszlo Lovasz; Katalin Vesztergombi

1999-01-01

141

Bent Bonds and Multiple Bonds.  

ERIC Educational Resources Information Center

Considers carbon-carbon multiple bonds in terms of Pauling's bent bond model, which allows direct calculation of double and triple bonds from the length of a CC single bond. Lengths of these multiple bonds are estimated from direct measurements on "bent-bond" models constructed of plastic tubing and standard kits. (CS)

Robinson, Edward A.; Gillespie, Ronald J.

1980-01-01

142

Optimized geometry and vibrational spectra and NBO analysis of solid state 2,4,6-tri-fluorobenzoic acid hydrogen bonded dimer  

NASA Astrophysics Data System (ADS)

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.

Mukherjee, V.; Singh, N. P.; Yadav, R. A.

2011-03-01

143

Geometric Modelling with CASL  

Microsoft Academic Search

This paper presents an experiment that demonstrates the feasibility of successfully applying CASL to design 3D geometric modelling\\u000a software. It presents an abstract specification of a 3D geometric model, its basic constructive primitives together with the\\u000a definition of the rounding high-level operation. A novel methodology for abstractly specifying geometric operations is also\\u000a highlighted. It allows one to faithfully specify the

Franck Ledoux; Agnès Arnould; Pascale Le Gall; Yves Bertrand

2001-01-01

144

Shape design sensitivity analysis and optimization of three dimensional elastic solids using geometric modeling and automatic regridding. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

An automatic regridding method and a three dimensional shape design parameterization technique were constructed and integrated into a unified theory of shape design sensitivity analysis. An algorithm was developed for general shape design sensitivity analysis of three dimensional eleastic solids. Numerical implementation of this shape design sensitivity analysis method was carried out using the finite element code ANSYS. The unified theory of shape design sensitivity analysis uses the material derivative of continuum mechanics with a design velocity field that represents shape change effects over the structural design. Automatic regridding methods were developed by generating a domain velocity field with boundary displacement method. Shape design parameterization for three dimensional surface design problems was illustrated using a Bezier surface with boundary perturbations that depend linearly on the perturbation of design parameters. A linearization method of optimization, LINRM, was used to obtain optimum shapes. Three examples from different engineering disciplines were investigated to demonstrate the accuracy and versatility of this shape design sensitivity analysis method.

Yao, Tse-Min; Choi, Kyung K.

1987-01-01

145

Geometric Shapes in Architecture  

NSDL National Science Digital Library

A unit designed to improve students' understanding and appreciation of basic geometric shapes used in architecture. It describes various plane geometric figures and discusses in detail the properties of several of these figures. Perimeters and areas of polygons and circles are computed.

Fox, Lauretta J.

2007-02-22

146

Geometric Dimensioning Sentence Structure.  

ERIC Educational Resources Information Center

Explanations of geometric dimensioning symbols are provided to assist in the comprehension of the implied basic sentence structure of modern geometric dimensioning and tolerance. The proper identification and interpretation of the substantive language within several exemplary engineering drawings, otherwise called feature control frames, is…

McCuistion, Patrick J.

1991-01-01

147

Geometric Reasoning for Automated Planning  

NASA Technical Reports Server (NTRS)

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.

Clement, Bradley J.; Knight, Russell L.; Broderick, Daniel

2012-01-01

148

Geometrizing Relativistic Quantum Mechanics  

NASA Astrophysics Data System (ADS)

We propose a new approach to describe quantum mechanics as a manifestation of non-Euclidean geometry. In particular, we construct a new geometrical space that we shall call Qwist. A Qwist space has a extra scalar degree of freedom that ultimately will be identified with quantum effects. The geometrical properties of Qwist allow us to formulate a geometrical version of the uncertainty principle. This relativistic uncertainty relation unifies the position-momentum and time-energy uncertainty principles in a unique relation that recover both of them in the non-relativistic limit.

Falciano, F. T.; Novello, M.; Salim, J. M.

2010-12-01

149

Geometric Differential Equations.  

National Technical Information Service (NTIS)

The purpose of the report is to present, however briefly, the contributions of a few outstanding authors to the development of geometric differential equations. The first author considered is Poincare, the true founder of the topic.

S. Lefschetz

1971-01-01

150

Geometric intrinsic symmetries  

SciTech Connect

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.

Gozdz, A., E-mail: Andrzej.Gozdz@umcs.lublin.pl; Szulerecka, A.; Pedrak, A. [University of Maria Curie-Sklodowska, Institute of Physics, Department of Mathematical Physics (Poland)] [University of Maria Curie-Sklodowska, Institute of Physics, Department of Mathematical Physics (Poland)

2013-08-15

151

Geometric correlations and multifractals.  

National Technical Information Service (NTIS)

There are many situations where the usual statistical methods are not adequate to characterize correlations in the system. To characterize such situations we introduce mutual correlation dimensions which describe geometric correlations in the system. Thes...

R. E. Amritkar

1991-01-01

152

Information Intrinsic Geometric Flows  

NASA Astrophysics Data System (ADS)

Geometric Flow Theory is cross fertilized by diverse elements coming from Pure Mathematic and Mathematical Physic, but its foundation is mainly based on Riemannian Geometry, as explained by M. Berger in a recent panoramic view of this discipline, its extension to complex manifolds, the Erich Kähler's Geometry, vaunted for its unabated vitality by J.P. Bourguignon, and Minimal Surface Theory. This paper would like to initiate seminal studies for applying intrinsic geometric flows in the framework of information geometry theory. More specifically, after having introduced Information metric deduced for Complex Auto-Regressive (CAR) models from Fisher Matrix (Siegel Metric and Hyper-Abelian Metric from Entropic Kähler Potential), we study asymptotic behavior of reflection coefficients of CAR models driven by intrinsic Information geometric Kähler-Ricci and Calabi flows. These Information geometric flows can be used in different contexts to define distance between CAR models interpreted as geodesics of Entropy Manifold. We conclude with potential application of Intrinsic Geometric Flow on Gauss Map to transform Manifold of any dimension by mean of Generalized Weierstrass Formula introduced by Kenmotsu that can represent arbitrary surfaces with non-vanishing mean curvature in terms of the mean curvature function and the Gauss map. One of the advantages of the generalized formulae is that they allow to construct a new class of deformations of surfaces by use of Intrinsic Geometric Flow on Gauss Map. We conclude with the Heat equation interpretation in the framework of Information Geometry.

Barbaresco, Frédéric

2006-11-01

153

Chemical Bonds  

NSDL National Science Digital Library

Electrons are key to forming the two broad categories of chemical bonds: covalent and ionic. Atoms, which have a nucleus surrounded by electrons, are represented in several different ways. In the Chemical Bonds activity, students explore the different kinds of chemical bonds that can form, ranging from non-polar covalent to ionic. In the model depicted above students adjust the electronegativity of two atoms and see the effect it has on electron distribution and bond type.

Consortium, The C.

2011-12-11

154

Sticker Bonding.  

ERIC Educational Resources Information Center

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)

Frazier, Laura Corbin

2000-01-01

155

Geometric structure of percolation clusters.  

PubMed

We investigate the geometric properties of percolation clusters by studying square-lattice bond percolation on the torus. We show that the density of bridges and nonbridges both tend to 1/4 for large system sizes. Using Monte Carlo simulations, we study the probability that a given edge is not a bridge but has both its loop arcs in the same loop and find that it is governed by the two-arm exponent. We then classify bridges into two types: branches and junctions. A bridge is a branch iff at least one of the two clusters produced by its deletion is a tree. Starting from a percolation configuration and deleting the branches results in a leaf-free configuration, whereas, deleting all bridges produces a bridge-free configuration. Although branches account for ?43% of all occupied bonds, we find that the fractal dimensions of the cluster size and hull length of leaf-free configurations are consistent with those for standard percolation configurations. By contrast, we find that the fractal dimensions of the cluster size and hull length of bridge-free configurations are given by the backbone and external perimeter dimensions, respectively. We estimate the backbone fractal dimension to be 1.643 36(10). PMID:24580185

Xu, Xiao; Wang, Junfeng; Zhou, Zongzheng; Garoni, Timothy M; Deng, Youjin

2014-01-01

156

Toughness governs the rupture of the interfacial H-bond assemblies at a critical length scale in hybrid materials.  

PubMed

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

Sakhavand, Navid; Muthuramalingam, Prakash; Shahsavari, Rouzbeh

2013-06-25

157

Geometric sensitivity of ClearPET™ Neuro  

NASA Astrophysics Data System (ADS)

ClearPET™ Neuro is a small-animal positron emission tomography (PET) scanner dedicated to brain studies on rats and primates. The design of ClearPET™ Neuro leads to a specific geometric sensitivity, characterized by inhomogeneous and, depending on the measurement setup, even incomplete data. With respect to reconstruction techniques, homogeneous and complete data sets are a 'must' for analytical reconstruction methods, whereas iterative methods take the geometrical sensitivity into account during the reconstruction process. Nevertheless, here a homogeneous geometric sensitivity over the field of view is highly desirable. Therefore, this contribution aims at studying the impact of different scanner geometries and measurement setups on the geometric sensitivity. A data set of coincident events is computed for certain settings that contains each possible crystal combination once. The lines of response are rebinned into normalizing sinograms and backprojected into sensitivity images. Both, normalizing sinograms and sensitivity images mirror the geometric sensitivity and therefore, provide information which setting enables most complete and homogeneous data sets. An optimal measurement setup and scanner geometry in terms of homogeneous geometric sensitivity is found by analyzing the sensitivity images.

Gundlich, Brigitte; Weber, Simone

2007-02-01

158

Optimizing HVOF Spray Parameters to Maximize Bonding Strength of WC-CrC-Ni Coatings on AISI 304L Stainless Steel  

NASA Astrophysics Data System (ADS)

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.

Thiruvikraman, C.; Balasubramanian, V.; Sridhar, K.

2014-03-01

159

Optimizing HVOF Spray Parameters to Maximize Bonding Strength of WC-CrC-Ni Coatings on AISI 304L Stainless Steel  

NASA Astrophysics Data System (ADS)

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.

Thiruvikraman, C.; Balasubramanian, V.; Sridhar, K.

2014-06-01

160

Valence State Driven Site Preference in the Quaternary Compound Ca5MgAgGe5: An Electron-Deficient Phase with Optimized Bonding.  

PubMed

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 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 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, Siméon; Lidin, Sven; Zhang, Yuemei; Miller, Gordon J

2014-05-01

161

Algebraic geometric codes  

NASA Technical Reports Server (NTRS)

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.

Shahshahani, M.

1991-01-01

162

Implicit learning of geometric eigenfaces.  

PubMed

The human visual system can implicitly extract a prototype of encountered visual objects (Posner & Keele, 1968). While learning a prototype provides an efficient way of encoding objects at the category level, discrimination among individual objects requires encoding of variations among them as well. Here we show that in addition to the prototype, human adults also implicitly learn the feature correlations that capture the most significant geometric variations among faces. After studying a group of synthetic faces, observers mistook as seen previously unseen faces representing the first two principal components (eigenfaces, Turk & Pentland, 1991) of the studied faces at significantly higher rates than the correct recognition of the faces actually studied. Implicit learning of the most significant eigenfaces provides an optimal way for encoding variations among faces. The data thus extend the types of summary statistics that can be implicitly extracted by the visual system to include several principal components. PMID:23911769

Gao, Xiaoqing; Wilson, Hugh R

2014-06-01

163

ACS SBC Geometric Distortion Calibration  

NASA Astrophysics Data System (ADS)

This activity will obtain a series of images to evaluate the geometric distortion over the field of view of the ACS SBC channel, after its image quality has been optimized with the corrector mechanism. Images will be obtained in filter F125LP, with a pattern of POS-TARG offsets in each axis. These data will be complemented by the images of the same field obtained in proposal 9024, "ACS SBC Flat Field Strability", which utilizes a similar image offsetting technique at larger spatial scales. The observations may be scheduled back-to-back with those from proposal 9024. NGC 6681 {18.7 h, -32 deg} will be the target, as this star field has been used extensively by the STIS program for UV PSF measurement and photometry.

Hartig, George

2001-07-01

164

Effect of bonding on the performance of a piezoactuator-based active control system  

NASA Technical Reports Server (NTRS)

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.

Baz, A.; Poh, S.

1987-01-01

165

Geometric Series via Probability  

ERIC Educational Resources Information Center

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…

Tesman, Barry

2012-01-01

166

1500 System Geometric Dictionary.  

ERIC Educational Resources Information Center

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…

Peloquin, Paul V.

167

Geometric grid generation  

NASA Technical Reports Server (NTRS)

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.

Ives, David

1995-01-01

168

Geometric Algorithms on CUDA  

Microsoft Academic Search

The recent launch of the NVIDIA CUDA technology has opened a new era in the young field of GPGPU (General Purpose computation on GPUs). This technology allows the design and implementation of parallel algorithms in a much simpler way than previous approaches based on shader programming. The present work explores the possibilities of CUDA for solving basic geometric problems on

Antonio J. Rueda Ruiz; Lidia M. Ortega

2008-01-01

169

Attributes of Geometric Shapes  

NSDL National Science Digital Library

This resource is a fun and engaging activity that will allow the students to identify and name shapes by their attributes. The students will move around and construct various geometric figures in order to build a solid understanding of the figures.

Banek, Michael

2012-06-18

170

A Geometric Scavenger Hunt  

ERIC Educational Resources Information Center

Children possess a genuine curiosity for exploring the natural world around them. One third grade teacher capitalized on this inherent trait by leading her students on "A Geometric Scavenger Hunt." The four-lesson inquiry investigation described in this article integrates mathematics and science. Among the students' discoveries was the fact that…

Smart, Julie; Marshall, Jeff

2007-01-01

171

Geometric simulation of flexible motion in proteins.  

PubMed

This chapter describes the use of physically simplified analysis and simulation methods-pebble-game rigidity analysis, coarse-grained elastic network modeling, and template-based geometric simulation-to explore flexible motion in protein structures. Substantial amplitudes of flexible motion can be explored rapidly in an all-atom model, retaining realistic covalent bonding, steric exclusion, and a user-defined network of noncovalent polar and hydrophobic interactions, using desktop computing resources. Detailed instructions are given for simulations using FIRST/FRODA software installed on a UNIX/Linux workstation. Other implementations of similar methods exist, particularly NMSim and FRODAN, and are available online. Topics covered include rigidity analysis and constraints, geometric simulation of flexible motion, targeting between known structures, and exploration of motion along normal mode eigenvectors. PMID:24061922

Wells, Stephen A

2014-01-01

172

Geometric quantum discord with Bures distance  

NASA Astrophysics Data System (ADS)

We define a new measure of quantum correlations in bipartite quantum systems given by the Bures distance of the system state to the set of classical states with respect to one subsystem, that is, to the states with zero quantum discord. Our measure is a geometrical version of the quantum discord. As the latter it quantifies the degree of non-classicality in the system. For pure states it is identical to the geometric measure of entanglement. We show that for mixed states it coincides with the optimal success probability of an ambiguous quantum state discrimination task. Moreover, the closest zero-discord states to a state ? are obtained in terms of the corresponding optimal measurements.

Spehner, D.; Orszag, M.

2013-10-01

173

Geometric continuity of parametric curves: constructions of geometrically continuous splines  

Microsoft Academic Search

Some observations are made concerning the source and nature of shape parameters. It is then described how Bezier curve segments can be stitched together with G1 or G2 continuity, using geometric constructions. These constructions lead to the development of geometric constructions for quadratic G1 and cubic G2 Beta-splines. A geometrically continuous subclass of Catmull-Rom splines based on geometric continuity and

Brian A. Barsky; Tony D. DeRose

1990-01-01

174

Adaptive fuzzy process control of integrated circuit wire bonding  

Microsoft Academic Search

One step in the assembly of integrated circuits is wire bonding, requiring expert knowledge to optimize critical process characteristics. This paper describes a fuzzy logic controller which sets parameters for the wire bonding process for gold ball wire bonds, specifically controlling bonded ball diameter and shear strength density. While the focus is on control of ball bonds, the method is

Clark D. Kinnaird; Alireza Khotanzad

1999-01-01

175

A Geometric Scavenger Hunt  

NSDL National Science Digital Library

Children possess a genuine curiosity for exploring the natural world around them. One third grade teacher capitalized on this inherent trait by leading her students on "A Geometric Scavenger Hunt." The four-lesson inquiry investigation described in this article integrates mathematics and science. Among the students discoveries was the fact that geometry was no longer just an isolated concept in their math books; rather, it provided a tool that allowed them to examine their world in a completely different way.

Marshall, Jeff; Smart, Julie

2007-10-01

176

Modelling ab initio non-bonded interactions for sigma bond, pi bond, and lone pair orbitals  

NASA Astrophysics Data System (ADS)

Ab initio eigenvalue splittings between symmetric and anti-symmetric combinations of energetically degenerate and environmentally equivalent molecular orbitals (MOs) are presented for pairs of ethane molecules and pairs of formaldehyde molecules in various geometrical configurations and as a function of separation. These weak non-bonded orbital interactions are computed for the MO of C?C sigma bond character in ethane, and for MOs of C?O pi bond character and those of axial and perpendicular oxygen lone pair character in formaldehyde. The relationship between simple orbital overlaps and the Hartree—Fock splittings in this beyond-van-der-Waals distance range is examined using overlaps based on valence bond wavefunctions constructed from single zeta Slater type orbitals. The role of the hydrogen atoms interposed in the region between the interacting MOs is examined. The suitability of the computed interactions as calibrations of effective transfer integrals needed in macromolecular electronic analyses is discussed.

Gruschus, James M.; Kuki, Atsuo

1992-05-01

177

Effect of intermolecular hydrogen bonding, vibrational analysis and molecular structure of a biomolecule: 5-Hydroxymethyluracil.  

PubMed

In the present work, the experimental and theoretical vibrational spectra of 5-hydroxymethyluracil were investigated. The FT-IR (4000-400cm(-1)) spectrum of the molecule in the solid phase was recorded. The geometric parameters (bond lengths and bond angles), vibrational frequencies, Infrared intensities of the title molecule in the ground state were calculated using density functional B3LYP and M06-2X methods with the 6-311++G(d,p) basis set for the first time. The optimized geometric parameters and theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data, and with the results found in the literature. The vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of 5-hydroxymethyluracil molecule was also simulated to evaluate the effect of intermolecular hydrogen bonding on its vibrational frequencies. It was observed that the NH stretching modes shifted to lower frequencies, while its in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular NH?O hydrogen bond. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and diagrams were presented. PMID:24632154

Ç?rak, Ça?r?; Sert, Yusuf; Ucun, Fatih

2014-06-01

178

Effect of intermolecular hydrogen bonding, vibrational analysis and molecular structure of a biomolecule: 5-Hydroxymethyluracil  

NASA Astrophysics Data System (ADS)

In the present work, the experimental and theoretical vibrational spectra of 5-hydroxymethyluracil were investigated. The FT-IR (4000-400 cm-1) spectrum of the molecule in the solid phase was recorded. The geometric parameters (bond lengths and bond angles), vibrational frequencies, Infrared intensities of the title molecule in the ground state were calculated using density functional B3LYP and M06-2X methods with the 6-311++G(d,p) basis set for the first time. The optimized geometric parameters and theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data, and with the results found in the literature. The vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of 5-hydroxymethyluracil molecule was also simulated to evaluate the effect of intermolecular hydrogen bonding on its vibrational frequencies. It was observed that the Nsbnd H stretching modes shifted to lower frequencies, while its in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular Nsbnd H⋯O hydrogen bond. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and diagrams were presented.

Ç?rak, Ça?r?; Sert, Yusuf; Ucun, Fatih

2014-06-01

179

Forming Bonds.  

ERIC Educational Resources Information Center

Explains how one North Carolina school district was able to pass high-dollar bond issues for school construction. Discusses the planning and bidding processes, and the district's philosophy towards incorporating innovative changes in design and equipment. (GR)

Spoor, Dana L.

1998-01-01

180

Geometric Constructions with the Computer.  

ERIC Educational Resources Information Center

The computer can be used as a tool to represent and communicate geometric knowledge. With the appropriate software, a geometric diagram can be manipulated through a series of animation that offers more than one particular snapshot as shown in a traditional mathematical text. Geometric constructions with the computer enable the learner to see and…

Chuan, Jen-chung

181

Multigrid Geometric Active Contour Models  

Microsoft Academic Search

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

George Papandreou; Petros Maragos

2007-01-01

182

Limits: Geometric and Harmonic Series  

NSDL National Science Digital Library

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.

Mathematics, Illuminations N.

2010-05-26

183

Low-Stress Thermosonic Copper Ball Bonding  

Microsoft Academic Search

Thermosonic ball bonding processes on test chips with Al metallized bonding pads are optimized with one Au and two Cu wire types, all 25 mum diameter, obtaining average shear strengths of more than 120 MPa. The process temperature is ~110degC. Ball bonds made with Cu wire show at least 15% higher shear strength than those made with Au wire. The

Aashish Shah; Michael Mayer; Y. Norman Zhou; S. J. Hong; J. T. Moon

2009-01-01

184

Methods and apparatuses for signaling with geometric constellations  

NASA Technical Reports Server (NTRS)

Communication systems are described that use signal constellations, which have unequally spaced (i.e. geometrically shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR. In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d.sub.min, are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2012-01-01

185

Representing geometrical knowledge.  

PubMed Central

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.

Anderson, J A

1997-01-01

186

A vision system for inspection of ball bonds in integrated circuits  

Microsoft Academic Search

The paper describes a vision system for automatic inspection of the connecting part of the wire bond of an IC where the wire connects to the bond pad on the chip. It considers a popular type of such bonds known as `ball bond'. Using two-dimensional images taken from the top of the IC wafer, the system determines several geometric measures

Alireza Khotanzad; Haimanti Banerjee; Mandyam Srinath

1992-01-01

187

Optimizing Locomotion  

NASA Astrophysics Data System (ADS)

In this talk we will discuss two optimization topics related to low Reynolds number locomotion: optimal stroke patterns in linked swimmers and optimal fluid material properties in adhesive locomotion. In contrast to many optimization problems, we do not consider geometry, rather we optimize the swimming kinematics or fluid material properties for a given geometrical configuration. In the first case, we begin by optimizing stroke patterns for Purcell's 3-link swimmer. We model the swimmer as a jointed chain of three slender links moving in an inertialess flow. The swimmer is optimized for both efficiency and speed. In the second case, we analyze the adhesive locomotion used by common gastropods such as snails and slugs. Such organisms crawl on a solid substrate by propagating muscular waves of shear stress on a viscoelastic mucus. Using a simple mechanical model, we derive criteria for favorable fluid material properties to lower the energetic cost of locomotion.

Hosoi, Anette

2006-11-01

188

Noncommutative geometric regularization  

SciTech Connect

Studies in string theory and in quantum gravity suggest the existence of a finite lower bound to the possible resolution of lengths which, quantum theoretically, takes the form of a minimal uncertainty in positions {Delta}{ital x}{sub 0}. A finite minimal uncertainty in momenta {Delta}{ital p}{sub 0} has been motivated from the absence of plane waves on generic curved spaces. Both effects can be described as small noncommutative geometric features of space-time. In a path integral approach to the formulation of field theories on noncommutative geometries, we can now generally prove IR regularization for the case of noncommutative geometries which imply minimal uncertainties {Delta}{ital p}{sub 0} in momenta. {copyright} {ital 1996 The American Physical Society.}

Kempf, A. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 9EW (United Kingdom)] [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 9EW (United Kingdom)

1996-10-01

189

Geometric learning algorithms  

NASA Astrophysics Data System (ADS)

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.

Omohundro, Stephen M.

1990-06-01

190

Geometrical pattern learning  

SciTech Connect

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.

Goldberg, P.W.

1993-04-01

191

Geometric Mechanics of Periodic Pleated Origami  

NASA Astrophysics Data System (ADS)

Origami structures are mechanical metamaterials with properties that arise almost exclusively from the geometry of the constituent folds and the constraint of piecewise isometric deformations. Here we characterize the geometry and planar and nonplanar effective elastic response of a simple periodically folded Miura-ori structure, which is composed of identical unit cells of mountain and valley folds with four-coordinated ridges, defined completely by two angles and two lengths. We show that the in-plane and out-of-plane Poisson’s ratios are equal in magnitude, but opposite in sign, independent of material properties. Furthermore, we show that effective bending stiffness of the unit cell is singular, allowing us to characterize the two-dimensional deformation of a plate in terms of a one-dimensional theory. Finally, we solve the inverse design problem of determining the geometric parameters for the optimal geometric and mechanical response of these extreme structures.

Wei, Z. Y.; Guo, Z. V.; Dudte, L.; Liang, H. Y.; Mahadevan, L.

2013-05-01

192

Revisiting decomposition analysis of geometric constraint graphs  

Microsoft Academic Search

Geometric problems defined by constraints can be represented by geometric constraint graphs whose nodes are geometric elements and whose arcs represent geometric constraints. Reduction and decomposition are techniques commonly used to analyze geometric constraint graphs in geometric constraint solving. In this paper we first introduce the concept of deficit of a constraint graph. Then we give a new formalization of

Robert Joan-Arinyo; Antoni Soto-Riera; S. Vila-Marta; Josep Vilaplana-Pasto

2002-01-01

193

Revisiting decomposition analysis of geometric constraint graphs  

Microsoft Academic Search

Geometric problems defined by constraints can be represented by geometric constraint graphs whose nodes are geometric elements and whose arcs represent geometric constraints. Reduction and decomposition are techniques commonly used to analyze geometric constraint graphs in geometric constraint solving.In this paper we first introduce the concept of deficit of a constraint graph. Then we give a new formalization of the

Robert Joan-arinyo; Antoni Soto-riera; S. Vila-marta; Josep Vilaplana-pasto

2004-01-01

194

Insights on hydrogen-bond lifetimes in liquid and supercooled water.  

PubMed

We study the temperature dependence of the lifetime of geometric and geometric/energetic water hydrogen-bonds (H-bonds), down to supercooled water, through molecular dynamics. The probability and lifetime of H-bonds that break either by translational or librational motions and those of energetic broken H-bonds, along with the effects of transient broken H-bonds and transient H-bonds, are considered. We show that the fraction of transiently broken energetic H-bonds increases at low temperatures and that this energetic breakdown is caused by oxygen-oxygen electrostatic repulsions upon too small amplitude librations to disrupt geometric H-bonds. Hence, differences between geometric and energetic continuous H-bond lifetimes are associated with large H-bond energy fluctuations, in opposition to moderate geometric fluctuations, within common energetic and geometric H-bond definition thresholds. Exclusion of transient broken H-bonds and transient H-bonds leads to H-bond definition-independent mean lifetimes and activation energies, ~11 kJ/mol, consistent with the reactive flux method and experimental scattering results. Further, we show that power law decay of specific temporal H-bond lifetime probability distributions is associated with librational and translational motions that occur on the time scale (~0.1 ps) of H-bond breaking /re-forming dynamics. While our analysis is diffusion-free, the effect of diffusion on H-bond probability distributions where H-bonds are allowed to break and re-form, switching acceptors in between, is shown to result in neither exponential nor power law decay, similar to the reactive flux correlation function. PMID:24279452

Martiniano, H F M C; Galamba, N

2013-12-19

195

Hydrogen Bonding Interactions of Radicals  

Microsoft Academic Search

Hydrogen bonding interactions of organic radicals are systematically studied using diverse ab initio and density functional theory (DFT) methods. It is found that open-shell hydrogen bonds with radical proton donors are more difficult to model than those with radical proton acceptors. The DFT methods perform significantly worse than the unrestricted second order Möller-Plesset perturbation (UMP2) method in both geometry optimization

Xiu-Juan Qi; Lei Liu; Yao Fu; Qing-Xiang Guo

2005-01-01

196

Geometric measure of quantum discord  

SciTech Connect

Dakic, Vedral, and Brukner [arXiv:1004.0190 (2010)] introduced a geometric measure of quantum discord and derived an explicit formula for any two-qubit state. This measure is significant in capturing quantum correlations from a geometric perspective. In this brief report, we evaluate the geometric measure of quantum discord for an arbitrary state and obtain an explicit and tight lower bound. Furthermore, we reveal an intrinsic feature of geometric measure of quantum discord by showing that it actually coincides with a simpler quantity based on von Neumann measurements.

Luo Shunlong; Fu Shuangshuang [Academy of Mathematics and Systems Science, Chinese Academy of Sciences, 100190 Beijing (China)

2010-09-15

197

Suballowable sequences and geometric permutations  

Microsoft Academic Search

We define suballowable sequences of permutations as a generalization of allowable sequences. We give a characterization of allowable sequences in the class of sub- allowable sequences, prove a Helly-type result on sets of permutations which form suballowable sequences, and show how suballowable sequences are related to prob- lems of geometric realizability. We discuss configurations of points and geometric permutations in

Andrei Asinowski

2008-01-01

198

Experiments on Geometric Image Enhancement  

Microsoft Academic Search

In this paper we experiments with geometric algorithms for image smoothing. Examples are given for MRI and ATR data. We emphasize experiments with the affine invariant geometric smoother or affine heat equation, originally developed for binary shape smoothing, and found to be efficient for gray-level images as well. Efficient numerical implementations of these flows give anisotropic diffusion processes which preserve

Guillermo Sapiro; Allen Tannenbaum; Yu-li You; Mostafa Kaveh

1994-01-01

199

Geometric Crossover for Biological Sequences  

Microsoft Academic Search

This paper extends a geometric framework for interpreting crossover and mutation (4) to the case of sequences. This representation is important because it is the link between artificial evolution and bio- logical evolution. We define and theoretically study geometric crossover for sequences under edit distance and show its intimate connection with the biological notion of sequence homology.

Alberto Moraglio; Riccardo Poli; Rolv Seehuus

2006-01-01

200

A geometric framework for nonlinear visual coding  

NASA Astrophysics Data System (ADS)

It is argued that important aspects of early and middle level visual coding may be understood as resulting from basic geometric processing of the visual input. The input is treated as a hypersurface defined by image intensity as a function of two spatial coordinates and time. Analytical results show how the Riemann curvature tensor R of this hypersurface represents speed and direction of motion. Moreover, the results can predict the selectivity of MT neurons for multiple motions and for motion in a direction along the optimal spatial orientation. Finally, a model based on integrated R components predicts global-motion percepts related to the barber-pole illusion.

Barth, Erhardt; Watson, Andrew B.

2000-08-01

201

Geometrical scaling law for laser shock processing  

NASA Astrophysics Data System (ADS)

Scaling approach to laser shock processing is studied by dimensional analysis and numerical simulation. The essential dimensionless parameters controlling the shock effect are studied, and a geometrical scaling law correlating the input laser parameters and the output strengthening effect parameters is presented. The numerical results show that there is a competition controlling mechanism between thickness of confined overlay and laser duration for the surface residual stress; the plastically affected depth increases linearly with increasing laser duration, increases quadratically with increasing laser power density, and is almost independent with the thickness of confined overlay. Based on the results, a window of the optimal working parameters is presented.

Wu, Xianqian; Tan, Qingming; Huang, Chenguang

2013-07-01

202

Chalcogen bond: a sister noncovalent bond to halogen bond.  

PubMed

A sister noncovalent bond to halogen bond, termed chalcogen bond, is defined in this article. By selecting the complexes H(2)CS...Cl(-), F(2)CS...Cl(-), OCS...Cl(-), and SCS...Cl(-) as models, the bond-length change, interaction energy, topological property of the electron charge density and its Laplacian, and the charge transfer of the chalcogen bond have been investigated in detail theoretically. It was found that the similar misshaped electron clouds of the chalcogen atom and the halogen atom result in the similar properties of the chalcogen bond and the halogen bond. Experimental results are in good agreement with the theoretical predictions. PMID:19537765

Wang, Weizhou; Ji, Baoming; Zhang, Yu

2009-07-16

203

Geometrical method of decoupling  

NASA Astrophysics Data System (ADS)

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.

Baumgarten, C.

2012-12-01

204

Pi Bond Orders and Bond Lengths  

ERIC Educational Resources Information Center

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)

Herndon, William C.; Parkanyi, Cyril

1976-01-01

205

Correlated algebraic-geometric codes  

NASA Astrophysics Data System (ADS)

We define a new family of error-correcting codes based on algebraic curves over finite fields, and develop efficient list decoding algorithms for them. Our codes extend the class of algebraic-geometric (AG) codes via a (nonobvious) generalization of the approach in the recent breakthrough work of Parvaresh and Vardy (2005). Our work shows that the PV framework applies to fairly general settings by elucidating the key algebraic concepts underlying it. Also, more importantly, AG codes of arbitrary block length exist over fixed alphabets Sigma , thus enabling us to establish new trade-offs between the list decoding radius and rate over a bounded alphabet size. The work of Parvaresh and Vardy (2005) was extended in Guruswami and Rudra (2006) to give explicit codes that achieve the list decoding capacity (optimal trade-off between rate and fraction of errors corrected) over large alphabets. A similar extension of this work along the lines of Guruswami and Rudra could have substantial impact. Indeed, it could give better trade-offs than currently known over a fixed alphabet (say, GF(2^{12}) ), which in turn, upon concatenation with a fixed, well-understood binary code, could take us closer to the list decoding capacity for binary codes. This may also be a promising way to address the significant complexity drawback of the result of Guruswami and Rudra, and to enable approaching capacity with bounded list size independent of the block length (the list size and decoding complexity in their work are both n^{Omega(1/\\varepsilon)} where \\varepsilon is the distance to capacity). Similar to algorithms for AG codes from Guruswami and Sudan (1999) and (2001), our encoding/decoding algorithms run in polynomial time assuming a natural polynomial-size representation of the code. For codes based on a specific ``optimal'' algebraic curve, we also present an expected polynomial time algorithm to construct the requisite representation. This in turn fills an important void in the literature by presenting an efficient construction of the representation often assumed in the list decoding algorithms for AG codes.

Guruswami, Venkatesan; Patthak, Anindya C.

2008-03-01

206

Geometric integration in Born-Oppenheimer molecular dynamics  

NASA Astrophysics Data System (ADS)

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.

Odell, Anders; Delin, Anna; Johansson, Börje; Cawkwell, Marc J.; Niklasson, Anders M. N.

2011-12-01

207

Geometric integration in Born-Oppenheimer molecular dynamics.  

PubMed

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. PMID:22168678

Odell, Anders; Delin, Anna; Johansson, Börje; Cawkwell, Marc J; Niklasson, Anders M N

2011-12-14

208

Repeating Decimals and Geometric Series  

NSDL National Science Digital Library

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 âmultiply, subtract, and solveâ 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.

2011-01-01

209

Optical traps with geometric aberrations  

SciTech Connect

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.

Roichman, Yael; Waldron, Alex; Gardel, Emily; Grier, David G

2006-05-20

210

Algebraic, geometric, and stochastic aspects of genetic operators  

NASA Technical Reports Server (NTRS)

Genetic algorithms for function optimization employ genetic operators patterned after those observed in search strategies employed in natural adaptation. Two of these operators, crossover and inversion, are interpreted in terms of their algebraic and geometric properties. Stochastic models of the operators are developed which are employed in Monte Carlo simulations of their behavior.

Foo, N. Y.; Bosworth, J. L.

1972-01-01

211

The Analysis of Geometrically Nonlinear Elastic-Plastic Space Frames  

Microsoft Academic Search

The establishment of the real stress-strain state of the structure is one of the most important problems for designing and undertaking the reconstruction of building constructions as well as making calculations for the purpose of optimizing cross-sections of various structural elements. This task can be achieved by analysing the structure as a geometrically nonlinear system (refusing an assumption of small

Romanas Karkauskas; Michail Popov

2011-01-01

212

How to Water Carrots: Geometric Coverage Problems for Point Sets  

Microsoft Academic Search

The problem. We study a new geometric optimization problem which arises in carrot crop management (10), as well as wireless network design and various other fa- cililty location problems. The task is to select a number of locations t j for the sprinklers, and assign a radius r j to each sprinkler. A carrot pi is covered iff it is

Helmut Alt; Esther M. Arkin; Herve Br; Jeff Erickson; Sue Whitesides; Kim Whittlesey

213

A GEOMETRIC ACTIVE CONTOUR MODEL FOR HIGHWAY EXTRACTION  

Microsoft Academic Search

In this paper, a new framework for semi-automatic feature extraction is developed and applied to highway extraction and vehicle detection from multiple-frame aerial photographs. The basis of the new framework is a geometric deformable model. This model refers to the minimization of an objective function that connects the optimization problem with the propagation of regular curves. The implementation of curve

Xutong Niu

2006-01-01

214

Geometrical Methods of Space Geodesy.  

National Technical Information Service (NTIS)

The fundemental principles and geometrical origins of the development of coordinated geodetic grids and the methods of coordinate tie-in of fixed and moving objects from observations of artificial earth satellites are discussed. The topics discussed inclu...

A. P. Tishchenko

1972-01-01

215

Geometric Design and Operational Effects,  

National Technical Information Service (NTIS)

The 14 papers in the report deal with the following areas: operational effects of the longer and wider combination vehicles on the geometry of diamond interchanges; operational and economic considerations in an evaluation of geometric design alternatives;...

B. M. Rajappan A. Polus P. R. Stefaniak W. S. Homburger T. Urbanik

1987-01-01

216

Large Consistent Geometric Landmark Maps  

Microsoft Academic Search

The autonomous operation of an intelligent service robot in practical applications requires that the robot builds up a map\\u000a of the environment by itself, even for large environments like supermarkets.\\u000a \\u000a This paper presents a solution to the problem of building large consistent maps consisting of geometric landmarks. This solution\\u000a consists of three basic steps: - incremental extraction of geometric landmarks

Wolfgang D. Rencken; Wendelin Feiten; Martin Soika

2000-01-01

217

Halogen bonds in crystal TTF derivatives: an ab initio quantum mechanical study.  

PubMed

The stabilisation energies of five ionic and neutral organic crystal structures containing various halogen bonds (I···I, Br···Br, I···Br, I···S and Br···S) were calculated using the DFT-D3 method (B97D/def2-QZVP). Besides them, the ionic I3(-)···I2 and neutral I2···I2, complexes (in the crystal geometries) were also studied. The nature of the bonds was deduced from the electrostatic potential evaluated for all subsystems. In almost all the cases, the ?-hole was positive; it was negative only for the ionic I3(-) system (although more positive than the respective belt value). The strongest halogen bonds were those that involved iodine as a halogen-bond donor and acceptor. Among ionic X···I3(-) and neutral X···I2 and X···Y dimers, the neutral X···I2 complexes were, surprisingly enough, the most stable; the highest stabilisation energy of 13.8 kcal mol(-1) was found for the I2···1,3-dithiole-2-thione-4-carboxylic acid complex. The stabilisation energies of the ionic I3(-)···I2 and neutral I2···1,3-dithiole-2-thione-4-carboxylic acid (20.2 and 20.42 kcal mol(-1), respectively) complexes are very high, which is explained by the favourable geometrical arrangement, allowing the formation of a strong halogen bond. An I···I halogen bond also exists in the neutral I2···I2 complex, having only moderate stabilisation energy (3.9 kcal mol(-1)). This stabilisation energy was, however, shown to be close to that in the optimal gas-phase L-shaped I2···I2 complex. In all the cases, the dispersion energy is important and comparable to electrostatic energy. Only in strong halogen bonds (e.g. I3(-)···I2), the electrostatic energy becomes dominant. PMID:24343344

Deepa, P; Pandiyan, B Vijaya; Kolandaivel, P; Hobza, Pavel

2014-02-01

218

Unified geometric calibration and image registration for detached small animal SPECT\\/CT  

Microsoft Academic Search

The aim of this study is to develop a unified optimization method to estimate the complete parameters about geometric calibration of system misalignment for both cone-beam CT and pinhole SPECT, and parameters about coordinate transformation of image registration for these detached systems. The uniform projection equations are derived for both cone-beam and pinhole imaging geometry. Complete geometric parameters are estimated

Xuezhu Zhang; Fangfu Chen; Yongping Li; Qin Wei; Hualin Zhang; Yujin Qi

2009-01-01

219

Geometric optical image aberrations of single and double mirrors.  

PubMed

The advantages and disadvantages of single and double mirror systems are considered. Geometrical image aberrations of spherical and paraboloidal single mirrors are given as functions of the focal number and angle of field, and geometrical image aberrations of paraboloidal-hyperboloidal double mirror systems are given as functions of primary focal number, secondary magnification, angle of field, and mutual position tolerances. The image aberrations for present and future diameter ranges are discussed in relation to wave optical limits. Optimal sizes of uncorrected fields of view are derived for different focal numbers. PMID:20072215

Tschunko, H F; Hurwitz, M G

1969-02-01

220

Planning optimal grasps  

Microsoft Academic Search

The authors address the problem of planning optimal grasps. Two general optimality criteria that consider the total finger force and the maximum finger force are introduced and discussed. Their formalization using various metrics on a space of generalized forces is detailed. The geometric interpretation of the two criteria leads to an efficient planning algorithm. An example of its use in

Carlo Ferrari; John Canny

1992-01-01

221

Architectural Layout Design Optimization  

NSDL National Science Digital Library

This joint effort between architecture and mechanical engineering researchers at the University of Michigan applied geometrical and topological optimization techniques to building floorplan layout. In the course of their research, they developed an optimization tool that is briefly described and can be downloaded from a Web site given in the paper.

Choudhary, Ruchi; Michalek, Jeremy J.; Papalambros, Panos Y.

2008-05-27

222

Metamorphic techniques and geometric reconfiguration principles  

Microsoft Academic Search

This paper proposes a geometric way to generate metamorphic configurations and investigates metamorphic principles based on geometrized displacement group. Metamorphic reconfiguration techniques are revealed as variations of kinematic joints, kinematic links and geometric orientation constraints specifically by examining invariant configuration properties of a mechanism. The nature of all these configuration changes belongs to geometric constraint category. Metamorphic configuration units are

Liping Zhang; Jian S Dai

2009-01-01

223

Geometric scalar theory of gravity  

NASA Astrophysics Data System (ADS)

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.

Novello, M.; Bittencourt, E.; Moschella, U.; Goulart, E.; Salim, J. M.; Toniato, J. D.

2013-06-01

224

Geometrical modelling of textile reinforcements  

NASA Technical Reports Server (NTRS)

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.

Pastore, Christopher M.; Birger, Alexander B.; Clyburn, Eugene

1995-01-01

225

Teleportation of geometric structures in 3D  

NASA Astrophysics Data System (ADS)

The simplest quantum teleportation algorithms can be represented in geometric terms in spaces of dimensions 3 (for real state vectors) and 4 (for complex state vectors). The geometric representation is based on geometric-algebra coding, a geometric alternative to the tensor-product coding typical of quantum mechanics. We discuss all the elementary ingredients of the geometric version of the algorithm: geometric analogs of states and controlled Pauli gates. A fully geometric presentation is possible if one employs a nonstandard representation of directed magnitudes, formulated in terms of colors defined via stereographic projection of a color wheel, and not by means of directed volumes.

Aerts, Diederik; Czachor, Marek; Or?owski, ?ukasz

2009-04-01

226

Geometrical Modeling of Steel Ropes  

NASA Astrophysics Data System (ADS)

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.

Stanová, Eva

2013-11-01

227

Geometrical Optics of Dense Aerosols  

SciTech Connect

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. __________________________________________________

Hay, Michael J.; Valeo, Ernest J.; Fisch, Nathaniel J.

2013-04-24

228

A geometric approach to direct minimization  

NASA Astrophysics Data System (ADS)

The approach presented, geometric direct minimization (GDM), is derived from purely geometrical arguments, and is designed to minimize a function of a set of orthonormal orbitals. The optimization steps consist of sequential unitary transformations of the orbitals, and convergence is accelerated using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) approach in the iterative subspace, together with a diagonal approximation to the Hessian for the remaining degrees of freedom. The approach is tested by implementing the solution of the self-consistent field (SCF) equations and comparing results with the standard direct inversion in the iterative subspace (DIIS) method. It is found that GDM is very robust and converges in every system studied, including several cases in which DIIS fails to find a solution. For main group compounds, GDM convergence is nearly as rapid as DIIS, whereas for transition metalcontaining systems we find that GDM is significantly slower than DIIS. A hybrid procedure where DIIS is used for the first several iterations and GDM is used thereafter is found to provide a robust solution for transition metal-containing systems.

van Voorhis, Troy; Head-Gordon, Martin

229

Nanoparticle fabrication by geometrically confined nanosphere lithography  

NASA Astrophysics Data System (ADS)

Arrays of metal nanoparticles, typically gold or silver, exhibit localized surface plasmon resonance, a phenomenon that has many applications, such as chemical and biological sensing. However, fabrication of metal nanoparticle arrays with high uniformity and repeatability, at a reasonable cost, is difficult. Nanosphere lithography (NSL) has been used before to produce inexpensive nanoparticle arrays through the use of monolayers of self-assembled microspheres as a deposition mask. However, control over the size and location of the arrays, as well as uniformity over large areas is poor, thus limiting its use to research purposes. In this paper, a new NSL method, called here geometrically confined NSL (GCNSL), is presented. In GCNSL, microsphere assembly is confined to geometric patterns defined in photoresist, allowing high-precision and large-scale nanoparticle patterning while still remaining low cost. Using this new method, it is demonstrated that 400 nm polystyrene microspheres can be assembled inside of large arrays of photoresist patterns. Results show that optimal microsphere assembly is achieved with long and narrow rectangular photoresist patterns. The combination of microsphere monolayers and photoresist patterns is then used as a deposition mask to produce silver nanoparticles at precise locations on the substrate with high uniformity, repeatability, and quality.

Denomme, Ryan C.; Iyer, Krishna; Kreder, Michael; Smith, Brendan; Nieva, Patricia M.

2013-07-01

230

A Geometrical Perspective for the Bargaining Problem  

PubMed Central

A new treatment to determine the Pareto-optimal outcome for a non-zero-sum game is presented. An equilibrium point for any game is defined here as a set of strategy choices for the players, such that no change in the choice of any single player will increase the overall payoff of all the players. Determining equilibrium for multi-player games is a complex problem. An intuitive conceptual tool for reducing the complexity, via the idea of spatially representing strategy options in the bargaining problem is proposed. Based on this geometry, an equilibrium condition is established such that the product of their gains over what each receives is maximal. The geometrical analysis of a cooperative bargaining game provides an example for solving multi-player and non-zero-sum games efficiently.

Wong, Kelvin Kian Loong

2010-01-01

231

Students' Perceptions of Parental Bonding Styles and Their Academic Burnout  

ERIC Educational Resources Information Center

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…

Shin, Hyojung; Lee, Jayoung; Kim, Boyoung; Lee, Sang Min

2012-01-01

232

Reduction of underpad stress in thermosonic copper ball bonding  

Microsoft Academic Search

Ball bonding processes on test chips with Al metallized bonding pads are optimized with one Au and two Cu wire types, all 25 mum diameter, obtaining average shear strengths of more than 120 MPa. The process temperature is about 110degC. The results demonstrate that ball bonds made with Cu wire show at least 15% higher shear strength than those made

A. Shah; M. Mayer; Y. Zhou; S. J. Hong; J. T. Moon

2008-01-01

233

Geometric tolerance verification using superquadrics  

Microsoft Academic Search

Standards for Geometric Tolerance Verification such as ANSI Y14.5 have been in practice for many years. These standards were developed for hard gage technology, and provide little guidance for how tolerances should be verified for flexible technologies such as coordinate measuring machines or laser scanners. As a result, most techniques used in practice do not make use of proper statistical

C. CAROLINA BÁRCENAS; PAUL M. GRIFFIN

2001-01-01

234

On Linear Geometric Difference Equations.  

National Technical Information Service (NTIS)

A geometric difference equation with polynomial coefficients up to degree r and parameter q lower than one in absolute value is studied. It is shown to have formal solutions depending on an arbitrary parameter. The solutions appear as series and their stu...

W. Hahn

1973-01-01

235

Highly connected random geometric graphs  

Microsoft Academic Search

Let P be a Poisson process of intensity one in a square Sn of area n. We construct a random geometric graph Gn,k by joining each point of P to its k nearest neighbours. For many applications it is desirable that Gn,k is highly connected, that is, it remains connected even after the removal of a small number of its

Paul N. Balister; Béla Bollobás; Amites Sarkar; Mark Walters

2009-01-01

236

Platonic Symmetry and Geometric Thinking  

ERIC Educational Resources Information Center

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…

Zsombor-Murray, Paul

2007-01-01

237

Geometric Transformations on a Microcomputer.  

ERIC Educational Resources Information Center

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)

Shilgalis, Thomas W.

1982-01-01

238

Geometrical Approach to Inverse Scattering  

Microsoft Academic Search

We present a geometrical approach to the inverse scattering problem for the Schrodinger and Klein-Gordon equations. For given scattering operator S we show uniqueness of the potential, we give explicit limits of the high-energy be- havior of the scattering operator, and we give reconstruction formulas for the potential. Our mathematical proofs closely follow physical intuition. A key observation is that

Volker Enss; Wolf Jung

239

Geometric Endoscopy and Mirror Symmetry  

Microsoft Academic Search

The geometric Langlands correspondence has been interpreted as the mirror symmetry of the Hitchin fibrations for two dual reductive groups. This mirror symmetry, in turn, reduces to T-duality on the generic Hitchin fibers, which are smooth tori. In this paper we study what happens when the Hitchin fibers on the B-model side develop orbifold singularities. These singularities correspond to local

Edward Frenkel; Edward Witten

2007-01-01

240

Celestial mechanics with geometric algebra  

NASA Technical Reports Server (NTRS)

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.

Hestenes, D.

1983-01-01

241

Tetrel bond-?-hole bond as a preliminary stage of the SN2 reaction.  

PubMed

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

Grabowski, S?awomir J

2014-02-01

242

Direct bonding of polymer to glass wafers using surface activated bonding (SAB) method at room temperature  

Microsoft Academic Search

The room temperature bonding of PEN film to PEN film, PET film to PET film and PEN film to non-alkali glass was performed by the modified SAB method. No void is observed at the bonding interface with the optimized condition.

Tadatomo Suga; Takashi Matsumae; Yoshiie Matsumoto; Masashi Nakano

2012-01-01

243

Numerical simulation of bond-slip between HSC and steel bar  

Microsoft Academic Search

Bond-slip relationship is very complex issue in the non-linear finite element analysis of beams. Three model beams with different bond length were constructed to study the mechanical properties. Based on the geometric parameters of the model beam as well as bond-slip curve obtained from experiments by former scholars, this paper has simulated the bond-slip relationship between steel bars and concrete

Wei-ping Zhao

2011-01-01

244

29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.  

Code of Federal Regulations, 2010 CFR

...bonds, separate bonds and additional bonding. 2580.412-20 Section 2580...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules §...

2009-07-01

245

29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.  

Code of Federal Regulations, 2010 CFR

...bonds, separate bonds and additional bonding. 2580.412-20 Section 2580...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules §...

2010-07-01

246

Dimensionality and Topology of Chemical Bonding Manifolds in Metal Clusters and Related Compounds.  

National Technical Information Service (NTIS)

The chemical bonding manifolds in metal cluster skeletons (as well as in skeletons of clusters of other elements such as boron or carbon) may be classified according to their dimensionalities and their chemical homeomorphism to various geometric structure...

R. B. King

1987-01-01

247

Bond strengths of two dental bonding systems.  

PubMed

A new bonding system named Kevloc has been introduced. It is based on acrylization of the metal surface with the goal of preventing the occurrence of a marginal gap between the metal and the resin. The purpose of this investigation was to determine the values of the shear bond strength achieved using the Kevloc technique on Ag-Pd (Auropal SE) and Co-Cr (Basil S) alloys and to compare them with those obtained with the OVS technique. The shear bond strengths were measured with the Smitz-Schulmayer shear test in a universal testing machine for polymer materials. A microscope image analyzer was used to measure the thickness of bonding layers and to reveal the possible occurrence of the marginal gap with both techniques. No marginal gap was detected with either technique. Kevloc provided better results than OVS only in a group of specimens tested after polymerization. Immersion in water and thermocycling reduced the initially high bond strength values of Kevloc specimens, whereas the bond strength values of OVS specimens remained unchanged regardless of which aging treatment was used. Microscopic examination did not reveal the existence of the marginal gap for either bonding system. According to the results obtained, it can be concluded that the Kevloc bonding system does not provide better shearing bond strength than the OVS bonding system. PMID:10920659

Vojvodic, D; Jerolimov, V; Zabarovic, D; Loncar, A

2000-07-01

248

The covered bond market  

Microsoft Academic Search

The covered bond market offers investors an alternative to developed country government securities. The valuation of covered bonds is complex. While there is some evidence of differences in the pricing of these bonds by nationality of issuer, these appear to be only weakly related to differences in the respective legislative frameworks. Recent cases show the pricing of covered bonds to

Frank Packer; Ryan Stever; Christian Upper

2007-01-01

249

Wire Bond Temperature Sensor  

Microsoft Academic Search

This work reports the first demonstration of a bond pad test structure with embedded thermopile sensors for the measurement of the transient temperature response during the wire bonding operation. This paper will present the design and operation of the bond pad test structure and show and discuss temperature measurements during the wire bonding operation. The test structure can be used

Shivesh Suman; Michael Gaitan; Yogendra Joshi; George Harman

250

The verdict geometric quality library.  

SciTech Connect

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.

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

251

Bouncing Balls and Geometric Series  

NSDL National Science Digital Library

The introduction to this intriguing exercise and article begins "If a ball bounces an infinite number of times, it must take an infinite amount of time to finish bouncing!" This piece appeared in The Journal of Online Mathematics and Its Applications in May 2007, and it was authored by Robert Styer and Morgan Besson of Villanova University. This particular article and its accompanying teaching module "explore the time and distance of a bouncing ball and leads to a study of the geometric series." Along with the actual article, this site also includes a video clip and several interactive Flash mathlets. It's a fun way to get students thinking about geometric series, and mathematics educators will definitely want to tell colleagues about the site as well. [KMG

Besson, Morgan; Styer, Robert

2007-05-01

252

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.

253

Bouncing Balls and Geometric Series  

NSDL National Science Digital Library

The introduction to this intriguing exercise and article begins "If a ball bounces an infinite number of times, it must take an infinite amount of time to finish bouncing!" This piece appeared in The Journal of Online Mathematics and Its Applications in May 2007, and it was authored by Robert Styer and Morgan Besson of Villanova University. This particular article and its accompanying teaching module "explore the time and distance of a bouncing ball and leads to a study of the geometric series." Along with the actual article, this site also includes a video clip and several interactive Flash mathlets. It's a fun way to get students thinking about geometric series, and mathematics educators will definitely want to tell colleagues about the site as well. [KMG

Besson, Morgan; Styer, Robert

2008-03-04

254

Geometrical modelling of textile reinforcements  

NASA Technical Reports Server (NTRS)

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.

Pastore, Christopher M.; Birger, Alexander B.; Clyburn, Eugene

1995-01-01

255

Ionicities of Boron-Boron Bonds in B12 Icosahedra  

Microsoft Academic Search

First-principles calculations are used to investigate ionicities of boron-boron bonds in B12 icosahedra. It is observed that the geometrical symmetry breaking of B12 icosahedra results in the spatial asymmetry of charge density on each boron-boron bond, and further in the ionicity of B12 icosahedra. The results calculated by a new ionicity scale, a population ionicity scale, indicate that the maximum

Julong He; Erdong Wu; Huitian Wang; Riping Liu; Yongjun Tian

2005-01-01

256

PALSAR Radiometric and Geometric Calibration  

Microsoft Academic Search

This paper summarizes the results obtained from geometric and radiometric calibrations of the Phased-Array L-Band Synthetic Aperture Radar (PALSAR) on the Advanced Land Observing Satellite, which has been in space for three years. All of the imaging modes of the PALSAR, i.e., single, dual, and full polarimetric strip modes and scanning synthetic aperture radar (SCANSAR), were calibrated and validated using

Masanobu Shimada; Osamu Isoguchi; Takeo Tadono; Kazuo Isono

2009-01-01

257

A geometric realization of confinement  

Microsoft Academic Search

We study the geometric realization of the Higgs phenomenon in type II string compactification on Calabi-Yau manifolds. The string description is most directly phrased in terms of confinement of magnetic flux, with magnetic charged states arising from D-branes wrapped around chains as opposed to cycles. The rest of the closed cycle of the D-brane world-volume is manifested as a confining

Brian R. Greene; David R. Morrison; Cumrun Vafa

1996-01-01

258

A geometric realization of confinement  

Microsoft Academic Search

We study the geometric realization of the Higgs phenomenon in type II string compactifications on Calabi-Yau manifolds. The string description is most directly phrased in terms of confinement of magnetic flux, with magnetic charged states arising from D-branes wrapped around chains as opposed to cycles. The rest of the closed cycle of the D-brane world-volume is manifested as a confining

Brian R. Greene; David R. Morrison; Cumrun Vafa

1996-01-01

259

Geometric Landau-Zener interferometry.  

PubMed

We propose a new type of interferometry, based on geometric phases accumulated by a periodically driven two-level system undergoing multiple Landau-Zener transitions. As a specific example, we study its implementation in a superconducting charge pump. We find that interference patterns appear as a function of the pumping frequency and the phase bias, and clearly manifest themselves in the pumped charge. We also show that the effects described should persist in the presence of realistic decoherence. PMID:22181761

Gasparinetti, S; Solinas, P; Pekola, J P

2011-11-11

260

Uncertainties in Bayesian Geometric Models  

Microsoft Academic Search

Deformable geometric models fit very naturally into the context of Bayesian analysis. The prior proba- bility of boundary shapes is taken to proportional to the negative exponential of the deformation energy used to control the boundary. This probabilistic in- terpretation is demonstrated using a Markov-Chain Monte-Carlo (MCMC)technique, which permits one to generate configurations that populate the prior. One of many

Kenneth M. Hanson; Gregory S. Cunningham; Robert J. Mckee

1999-01-01

261

Geometric compression through topological surgery  

Microsoft Academic Search

The abundance and importance of complex 3-D data bases in major industry segments, the affordability of interactive 3-D rendering for office and consumer use, and the exploitation of the Internet to distribute and share 3-D data have intensified the need for an effective 3-D geometric compression technique that would significantly reduce the time required to transmit 3-D models over digital

Gabriel Taubin; Jarek Rossignac

1998-01-01

262

Geometric Aspects of Mirror Symmetry  

Microsoft Academic Search

The geometric aspects of mirror symmetry are reviewed, with an eye towards\\u000afuture developments. Given a mirror pair (X,Y) of Calabi-Yau threefolds, the\\u000abest-understood mirror statements relate certain small corners of the moduli\\u000aspaces of X and of Y. We will indicate how one might go beyond such statements,\\u000aand relate the moduli spaces more globally. In fact, in the

David R. Morrison

2000-01-01

263

Geometrical content of Leslie coefficients  

NASA Astrophysics Data System (ADS)

In this work, we will study how the effective geometry acquired by nematic molecules under thermal vibration contribute to the determination of the Leslie coefficients. To do this, we will divide this work in two sections. In the first section, we present the geometrical fundamentals of the so-called Hess-Baalss (HB) approach [D. Baalss and S. Hess, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.57.86 57, 86 (1986)] where we show that its basic assumptions can be understood as a geometrical interpretation of de Gennes’ passage from the microscopic to the macroscopic order parameter. In the second section, we use an extended version of the HB approach [M. Simões, K. Yamaguti, and A. J. Palangana, Phys. Rev. EPHRVAO1539-375510.1103/PhysRevE.80.061701 80, 061701 (2009)] to obtain the geometrical contribution to each Leslie coefficient. Our results will be compared with experimental data, and we will show that the Miesowicz’s coefficients are connected as long as the ratio ?3/?4 between these Leslie coefficients can be considered small.

Simões, M.; da Silva, J. L. Correia

2011-05-01

264

Savings Bonds Value Calculator  

NSDL National Science Digital Library

From the Federal Reserve Bank of New York, this site computes the redemption value of users's US savings bonds. Easy-to-use pull-down menus allow visitors to enter information such as the date of issue and face value of their Series E bonds, Series EE bonds, and Series S bonds. After entering the information, the Calculator will then show a chart of issue dates and denominations and actual worth of the bonds, if cashed within a set period of time.

265

Direct bonding and beyond  

Microsoft Academic Search

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)

Jan Haisma; Nico Hattu; Esther Steding; Jan C. G. Vervest

2007-01-01

266

Geometric Moments Computed from the Hartley Transform.  

National Technical Information Service (NTIS)

Geometric moments are useful in pattern recognition, and several optical methods have been proposed for their calculation. This reprint presents a new hybrid optical/digital processor that computes the geometric moments using the recently introducted Hart...

B. V. Kumar

1986-01-01

267

LET'S BOND! A Chemical Bonding Webquest  

NSDL National Science Digital Library

Today we are going to use the internet to explore chemical bonding! Even though there are just a few questions for each website, you need to read the entire content. Don't worry about understanding all of it, but make sure that you are familiar with it! Stay on task and have fun! Let's start with some basics. Click on the link below and answer the questions on your worksheet under "Bonding Basics". Bonding Basics Good job! Lets move on and talk about ions. Ions are a big part of bonding, so make sure you get this section down pat! Click on the ...

Hicken, Mrs.

2009-04-08

268

Investing in Bonds.com  

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.

269

In-flight Geometric Calibration Plan  

NASA Technical Reports Server (NTRS)

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.

Jovanovic, V.

2000-01-01

270

Compression and Progressive Visualization of Geometric Models  

Microsoft Academic Search

The maximum compression, efficient transmission and fast rendering of geometric models is a complex problem for many reasons, thereby gaining a lot of attention from several areas, like compression and rendering of geometric models. Normally, the stripification algorithms are used to speed up the rendering of geometric models because they reduce the number of vertices sent to the graphics pipeline

Frutuoso G. M. Silva; Pranjul Yadav

271

GEOMETRIC MEASUREMENT COMPARISONS FOR ROCKWELL DIAMOND INDENTERS  

Microsoft Academic Search

In the uncertainty budget of Rockwell C hardness (HRC) tests, geometric error of the Rockwell diamond indenter is a major contributor. The geometric calibration of Rockwell diamond indenters has been a key issue for Rockwell hardness standardization. The National Institute of Standards and Technology (NIST) developed a microform calibration system based on a stylus instrument for the geometric calibration of

John Song; Samuel Low; Alan Zheng

272

A Geometric Nearest Point Algorithm for the Efficient Solution of the SVM Classification Task  

Microsoft Academic Search

Geometric methods are very intuitive and provide a theoretically solid approach to many optimization problems. One such optimization task is the support vector machine (SVM) classification, which has been the focus of intense theoretical as well as application-oriented research in machine learning. In this letter, the incorporation of recent results in reduced convex hulls (RCHs) to a nearest point algorithm

Michael E. Mavroforakis; Margaritis Sdralis; Sergios Theodoridis

2007-01-01

273

Real-Time Nondestructive Contact Resistance Method to Estimate Wire Bond Pull Force  

NASA Astrophysics Data System (ADS)

We estimate microelectronic wire bond quality nondestructively by measuring the contact resistance (CR) of the bond in situ during the bonding process. This measurement employs a Kelvin cross setup contacting the wedge, 25 um Al wire and an Au substrate. The results verify that the method can identify the bond process phases and predict whether the bonding was successful (94% classification accuracy). The method can be used for process control and optimization to create stronger bonds and higher yield.

Kurppa, R.; Seppänen, H.; Meriläinen, A.; Oinonen, M.; Hæggström, E.

2010-02-01

274

Hydroxide-catalyzed bonding  

NASA Technical Reports Server (NTRS)

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.

Gwo, Dz-Hung (Inventor)

2003-01-01

275

Geometric nomenclature and classification of RNA base pairs.  

PubMed Central

Non-Watson-Crick base pairs mediate specific interactions responsible for RNA-RNA self-assembly and RNA-protein recognition. An unambiguous and descriptive nomenclature with well-defined and nonoverlapping parameters is needed to communicate concisely structural information about RNA base pairs. The definitions should reflect underlying molecular structures and interactions and, thus, facilitate automated annotation, classification, and comparison of new RNA structures. We propose a classification based on the observation that the planar edge-to-edge, hydrogen-bonding interactions between RNA bases involve one of three distinct edges: the Watson-Crick edge, the Hoogsteen edge, and the Sugar edge (which includes the 2'-OH and which has also been referred to as the Shallow-groove edge). Bases can interact in either of two orientations with respect to the glycosidic bonds, cis or trans relative to the hydrogen bonds. This gives rise to 12 basic geometric types with at least two H bonds connecting the bases. For each geometric type, the relative orientations of the strands can be easily deduced. High-resolution examples of 11 of the 12 geometries are presently available. Bifurcated pairs, in which a single exocyclic carbonyl or amino group of one base directly contacts the edge of a second base, and water-inserted pairs, in which single functional groups on each base interact directly, are intermediate between two of the standard geometries. The nomenclature facilitates the recognition of isosteric relationships among base pairs within each geometry, and thus facilitates the recognition of recurrent three-dimensional motifs from comparison of homologous sequences. Graphical conventions are proposed for displaying non-Watson-Crick interactions on a secondary structure diagram. The utility of the classification in homology modeling of RNA tertiary motifs is illustrated.

Leontis, N B; Westhof, E

2001-01-01

276

The Bond Market Association  

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.

1998-01-01

277

Geometrically Induced Interactions and Bifurcations  

NASA Astrophysics Data System (ADS)

In order to evaluate the proper boundary conditions in spin dynamics eventually leading to the emergence of natural and artificial solitons providing for strong interactions and potentials with monopole charges, the paper outlines a new concept referring to a curvature-invariant formalism, where superintegrability is given by a special isometric condition. Instead of referring to the spin operators and Casimir/Euler invariants as the generator of rotations, a curvature-invariant description is introduced utilizing a double Gudermann mapping function (generator of sine Gordon solitons and Mercator projection) cross-relating two angular variables, where geometric phases and rotations arise between surfaces of different curvature. Applying this stereographic projection to a superintegrable Hamiltonian can directly map linear oscillators to Kepler/Coulomb potentials and/or monopoles with Pöschl-Teller potentials and vice versa. In this sense a large scale Kepler/Coulomb (gravitational, electro-magnetic) wave dynamics with a hyperbolic metric could be mapped as a geodesic vertex flow to a local oscillator singularity (Dirac monopole) with spherical metrics and vice versa. Attracting fixed points and dynamic constraints are given by special isometries with magic precession angles. The nonlinear angular encoding directly provides for a Shannon mutual information entropy measure of the geodesic phase space flow. The emerging monopole patterns show relations to spiral Fresnel holography and Berry/Aharonov-Bohm geometric phases subject to bifurcation instabilities and singularities from phase ambiguities due to a local (entropy) overload. Neutral solitons and virtual patterns emerging and mediating in the overlap region between charged or twisted holographic patterns are visualized and directly assigned to the Berry geometric phase revealing the role of photons, neutrons, and neutrinos binding repulsive charges in Coulomb, strong and weak interaction.

Binder, Bernd

2010-01-01

278

Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations  

NASA Technical Reports Server (NTRS)

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.

Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin

2000-01-01

279

Hysteresis heating based induction bonding of composite materials  

Microsoft Academic Search

The viability of using magnetic particulate susceptor materials for induction heating during bonding of polymer matrix composites is well established in this work. The unique ability to offer localized heating, geometric flexibility, and self-controlled temperature is the major advantage of this technique. Hysteresis heating is tailored through careful design of the microstructure of nickel particulate polymer films (Ni\\/PSU). An excellent

Witchuda Suwanwatana

2004-01-01

280

Geometric analysis of wing sections  

NASA Technical Reports Server (NTRS)

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.

Chang, I.-CHUNG; Torres, Francisco J.; Tung, Chee

1995-01-01

281

Geometrical setting of solid mechanics  

NASA Astrophysics Data System (ADS)

The starting point in the geometrical setting of solid mechanics is to represent deformation process of a solid body as a trajectory in a convenient space with Riemannian geometry, and then to use the corresponding tools for its analysis. Based on virtual power of internal stresses, we show that such a configuration space is the (globally) symmetric space of symmetric positive-definite real matrices. From this unifying point of view, we shall analyse the logarithmic strain, the stress rate, as well as linearization and intrinsic integration of corresponding evolution equation.

Fiala, Zden?k

2011-08-01

282

Geometric action for nongeometric fluxes.  

PubMed

We give a geometrical interpretation of the nongeometric Q and R fluxes. To this end, we consider double field theory in a formulation that is related to the conventional one by a field redefinition taking the form of a T duality inversion. The R flux is a tensor under diffeomorphisms and satisfies a nontrivial Bianchi identity. The Q flux can be viewed as part of a connection that covariantizes the winding derivatives with respect to diffeomorphisms. We give a higher-dimensional action with a kinetic term for the R flux and a "dual" Einstein-Hilbert term containing the connection Q. PMID:23004959

Andriot, David; Hohm, Olaf; Larfors, Magdalena; Lüst, Dieter; Patalong, Peter

2012-06-29

283

Science, art and geometrical imagination  

NASA Astrophysics Data System (ADS)

From the geocentric, closed world model of Antiquity to the wraparound universe models of relativistic cosmology, the parallel history of space representations in science and art illustrates the fundamental rôle of geometric imagination in innovative findings. Through the analysis of works of various artists and scientists like Plato, Dürer, Kepler, Escher, Grisey or the author, it is shown how the process of creation in science and in the arts rests on aesthetical principles such as symmetry, regular polyhedra, laws of harmonic proportion, tessellations, group theory, etc., as well as on beauty, conciseness and an emotional approach of the world.

Luminet, Jean-Pierre

2011-06-01

284

Reduction of ultrasonic pad stress and aluminum splash in copper ball bonding  

Microsoft Academic Search

Given the cost and performance advantages associated with Cu wire, it is being increasingly seen as a candidate to replace Au wire for making interconnections in first level microelectronics packaging. A Cu ball bonding process is optimized with reduced pad stress and splash, using a 25.4?m diameter Cu wire. For ball bonds made with conventionally optimized bond force and ultrasonic

A. Shah; A. Rezvani; M. Mayer; Y. Zhou; J. Persic; J. T. Moon

2011-01-01

285

An algorithm for converting a virtual-bond chain into a complete polypeptide backbone chain  

NASA Technical Reports Server (NTRS)

A systematic analysis is presented of the algorithm for converting a virtual-bond chain, defined by the coordinates of the alpha-carbons of a given protein, into a complete polypeptide backbone. An alternative algorithm, based upon the same set of geometric parameters used in the Purisima-Scheraga algorithm but with a different "linkage map" of the algorithmic procedures, is proposed. The global virtual-bond chain geometric constraints are more easily separable from the loal peptide geometric and energetic constraints derived from, for example, the Ramachandran criterion, within the framework of this approach.

Luo, N.; Shibata, M.; Rein, R.

1991-01-01

286

A comparison of geometric parameters from PBE-based doubly hybrid density functionals PBE0-DH, PBE0-2, and xDH-PBE0  

NASA Astrophysics Data System (ADS)

We present a systematic investigation on the optimized geometric parameters for covalently bonded molecules, nonbonded intermolecular complexes, and transition state structures from three PBE (Perdew-Burke-Ernzerhof)-based doubly hybrid (DH) density functionals, namely PBE0-DH, PBE0-2, and xDH-PBE0. While the former two are the B2PLYP-type of DH functionals with no fit parameters, the latter is the XYG3-type of DH functional (xDH for short) with three fit parameters, whose energy expression is constructed by using density and orbital information from another standard (general) Kohn-Sham functional (i.e., PBE0) for doing the self-consistent field calculations. Generally good performances have been obtained with all three DH functionals, in particular, with xDH-PBE0.

Su, Neil Qiang; Adamo, Carlo; Xu, Xin

2013-11-01

287

[Indirect bonding technics].  

PubMed

The indirect bonding technique is pivotal for success in lingual orthodontics. There are different laboratory techniques available for indirect positioning and bonding of lingual brackets. Different approaches are presented and described to perform a clinical application. PMID:19552882

Sorel, Olivier; Mehdi, Sarah; Mano, Marie-Charlotte

2009-06-01

288

Prediction model for wire bonding process through adaptive neuro-fuzzy inference system  

Microsoft Academic Search

In the wire bonding process, different combinations of parameter values will directly affect wire bonding quality. The optimal combination of these parameter values is very important to ensure the overall process quality response. Therefore, it is necessary to investigate the effects and interactive relationship of the bonding parameters on the bonding quality. This paper chooses the response factors of shear

Jian Gao; Changhong Liu; Xin Chen; Detao Zheng; Ketian Li

2009-01-01

289

NPP VIIRS geometric performance status  

NASA Astrophysics Data System (ADS)

Visible Infrared Imager Radiometer Suite (VIIRS) instrument on-board the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) satellite is scheduled for launch in October, 2011. It is to provide satellite measured radiance/reflectance data for both weather and climate applications. Along with radiometric calibration, geometric characterization and calibration of Sensor Data Records (SDRs) are crucial to the VIIRS Environmental Data Record (EDR) algorithms and products which are used in numerical weather prediction (NWP). The instrument geometric performance includes: 1) sensor (detector) spatial response, parameterized by the dynamic field of view (DFOV) in the scan direction and instantaneous FOV (IFOV) in the track direction, modulation transfer function (MTF) for the 17 moderate resolution bands (M-bands), and horizontal spatial resolution (HSR) for the five imagery bands (I-bands); 2) matrices of band-to-band co-registration (BBR) from the corresponding detectors in all band pairs; and 3) pointing knowledge and stability characteristics that includes scan plane tilt, scan rate and scan start position variations, and thermally induced variations in pointing with respect to orbital position. They have been calibrated and characterized through ground testing under ambient and thermal vacuum conditions, numerical modeling and analysis. This paper summarizes the results, which are in general compliance with specifications, along with anomaly investigations, and describes paths forward for characterizing on-orbit BBR and spatial response, and for improving instrument on-orbit performance in pointing and geolocation.

Lin, Guoqing; Wolfe, Robert E.; Nishihama, Masahiro

2011-09-01

290

NPP VIIRS Geometric Performance Status  

NASA Technical Reports Server (NTRS)

Visible Infrared Imager Radiometer Suite (VIIRS) instrument on-board the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) satellite is scheduled for launch in October, 2011. It is to provide satellite measured radiance/reflectance data for both weather and climate applications. Along with radiometric calibration, geometric characterization and calibration of Sensor Data Records (SDRs) are crucial to the VIIRS Environmental Data Record (EDR) algorithms and products which are used in numerical weather prediction (NWP). The instrument geometric performance includes: 1) sensor (detector) spatial response, parameterized by the dynamic field of view (DFOV) in the scan direction and instantaneous FOV (IFOV) in the track direction, modulation transfer function (MTF) for the 17 moderate resolution bands (M-bands), and horizontal spatial resolution (HSR) for the five imagery bands (I-bands); 2) matrices of band-to-band co-registration (BBR) from the corresponding detectors in all band pairs; and 3) pointing knowledge and stability characteristics that includes scan plane tilt, scan rate and scan start position variations, and thermally induced variations in pointing with respect to orbital position. They have been calibrated and characterized through ground testing under ambient and thermal vacuum conditions, numerical modeling and analysis. This paper summarizes the results, which are in general compliance with specifications, along with anomaly investigations, and describes paths forward for characterizing on-orbit BBR and spatial response, and for improving instrument on-orbit performance in pointing and geolocation.

Lin, Guoqing; Wolfe, Robert E.; Nishihama, Masahiro

2011-01-01

291

Covalent and Ionic Bonds  

NSDL National Science Digital Library

Atoms can attain a more stable arrangement of electrons in their outermost shell by interacting with one another. An ionic bond is formed when electrons are transferred from one atom to the other. A covalent bond is formed when electrons are shared between atoms. The two cases shown represent extremes; often, covalent bonds form with a partial transfer (unequal sharing of electrons), resulting in a polar covalent bond

BEGIN:VCARD VERSION:2.1 FN:Bruce Alberts N:Alberts;Bruce REV:2005-04-16 END:VCARD; BEGIN:VCARD VERSION:2.1 FN:Dennis Bray N:Bray;Dennis REV:2005-04-16 END:VCARD; BEGIN:VCARD VERSION:2.1 FN:Alexander Johnson N:Johnson;Alexander REV:2005-04-16 END:VCARD; BEGIN:VCARD VERSION:2.1 FN:Julian Lewis N:Lewis;Julian REV:2005-04-16 END:VCARD; BEGIN:VCARD VERSION:2.1 FN:Martin Raff N:Raff;Martin REV:2005-04-16 END:VCARD; BEGIN:VCARD VERSION:2.1 FN:Keith Roberts N:Roberts;Keith REV:2005-04-16 END:VCARD

1998-07-01

292

Allosteric Disulfide Bonds  

Microsoft Academic Search

\\u000a Protein disulfide bonds link cysteine residues in the polypeptide chain. The bonds contribute, sometimes crucially, to protein\\u000a stability and function and are strongly conserved through the evolution of species. By analyzing the conservation of all structurally\\u000a validated disulfide bonds across 29 completely sequenced eukaryotic genomes, we found that disulfide-bonded cysteines are\\u000a even more conserved than tryptophan – the most conserved

Jason W. H. Wong; Philip J. Hogg

293

The geometric structure of single-walled nanotubes  

NASA Astrophysics Data System (ADS)

In this paper, we survey a number of existing geometric structures which have been proposed by the authors as possible models for various nanotubes. Atoms assemble into molecules following the laws of quantum mechanics, and in general computational approaches to predicting the molecular structure can be arduous and involve considerable computing time. Fortunately, nature favours minimum energy structures which tend to be either very symmetric or very unsymmetric, and which therefore can be analyzed from a geometrical perspective. The conventional rolled-up model of nanotubes completely ignores any effects due to curvature and the present authors have proposed a number of exact geometric models. Here we review a number of these recent developments relating to the geometry of nanotubes, including both the traditional rolled-up models and some exact polyhedral constructions. We review a number of formulae for four materials, carbon, silicon, boron and boron nitride, and we also include results for the case when the bond lengths may take on distinct values.

Lee, Richard K. F.; Cox, Barry J.; Hill, James M.

2010-06-01

294

The geometric structure of single-walled nanotubes.  

PubMed

In this paper, we survey a number of existing geometric structures which have been proposed by the authors as possible models for various nanotubes. Atoms assemble into molecules following the laws of quantum mechanics, and in general computational approaches to predicting the molecular structure can be arduous and involve considerable computing time. Fortunately, nature favours minimum energy structures which tend to be either very symmetric or very unsymmetric, and which therefore can be analyzed from a geometrical perspective. The conventional rolled-up model of nanotubes completely ignores any effects due to curvature and the present authors have proposed a number of exact geometric models. Here we review a number of these recent developments relating to the geometry of nanotubes, including both the traditional rolled-up models and some exact polyhedral constructions. We review a number of formulae for four materials, carbon, silicon, boron and boron nitride, and we also include results for the case when the bond lengths may take on distinct values. PMID:20648281

Lee, Richard K F; Cox, Barry J; Hill, James M

2010-06-01

295

Cis peptide bonds in proteins: residues involved, their conformations, interactions and locations1  

Microsoft Academic Search

An analysis of a non-redundant set of protein structures from the Brook- haven Protein Data Bank has been carried out to find out the residue pre- ference, local conformation, hydrogen bonding and other stabilizing interactions involving cis peptide bonds. This has led to a reclassification of turns mediated by cis peptides, and their average geometrical par- ameters have been evaluated.

Debnath Pal; Pinak Chakrabarti

1999-01-01

296

Rapid adhesive bonding concepts  

NASA Technical Reports Server (NTRS)

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.

Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

1984-01-01

297

Acrylic mechanical bond tests  

SciTech Connect

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.

Wouters, J.M.; Doe, P.J.

1991-02-01

298

On the nature of blueshifting hydrogen bonds.  

PubMed

The block-localized wave function (BLW) method can derive the energetic, geometrical, and spectral changes with the deactivation of electron delocalization, and thus provide a unique way to elucidate the origin of improper, blueshifting hydrogen bonds versus proper, redshifting hydrogen bonds. A detailed analysis of the interactions of F3 CH with NH3 and OH2 shows that blueshifting is a long-range phenomenon. Since among the various energy components contributing to hydrogen bonds, only the electrostatic interaction has long-range characteristics, we conclude that the contraction and blueshifting of a hydrogen bond is largely caused by electrostatic interactions. On the other hand, lengthening and redshifting is primarily due to the short-range n(Y)??*(X?H) hyperconjugation. The competition between these two opposing factors determines the final frequency change direction, for example, redshifting in F3 CH???NH3 and blueshifting in F3 CH???OH2 . This mechanism works well in the series Fn Cl3-n CH???Y (n=0-3, Y=NH3 , OH2 , SH2 ) and other systems. One exception is the complex of water and benzene. We observe the lengthening and redshifting of the O?H bond of water even with the electron transfer between benzene and water completely quenched. A distance-dependent analysis for this system reveals that the long-range electrostatic interaction is again responsible for the initial lengthening and redshifting. PMID:24862363

Mo, Yirong; Wang, Changwei; Guan, Liangyu; Braïda, Benoît; Hiberty, Philippe C; Wu, Wei

2014-07-01

299

Optimal bird migration revisited  

Microsoft Academic Search

Using optimality perspectives is now regarded as an essential way of analysing and understanding adaptations and behavioural\\u000a strategies in bird migration. Optimization analyses in bird migration research have diversified greatly during the two recent\\u000a decades with respect to methods used as well as to topics addressed. Methods range from simple analytical and geometric models\\u000a to more complex modeling by stochastic

Thomas Alerstam

300

Triangular spin tubes with bond randomness  

NASA Astrophysics Data System (ADS)

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.

Miura, Yoko; Manaka, Hirotaka

2013-06-01

301

Bonding thermoplastic polymers  

DOEpatents

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.

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

302

Geometric optimization of a micro heat sink with liquid flow  

Microsoft Academic Search

Over the course of the past decade, a number of investigations have been conducted to better understand the fluid flow and heat transfer in microchannel heat sinks, particularly as it pertains to applications involving the thermal control of electronic devices. In the current investigation, a detailed numerical simulation of the heat transfer occurring in silicon-based microchannel heat sinks has been

Ji Li; G. P. Peterson

2006-01-01

303

Optimal navigation and object finding without geometric maps or localization  

Microsoft Academic Search

In this paper we present a dynamic data structure, useful for robot navigation in an unknown, simply- connected planar environment. The guiding philoso- phy in this work is to avoid traditional problems such as complete map building and localization by con- structing a minimal representation based entirely on critical events in online sensor measurements made by the robot. Furthermore, this

Benjamín Tovar; Steven M. Lavalle; Rafael Murrieta-cid

2003-01-01

304

Gear optimization  

NASA Technical Reports Server (NTRS)

The use of formal numerical optimization methods for the design of gears is investigated. To achieve this, computer codes were developed for the analysis of spur gears and spiral bevel gears. These codes calculate the life, dynamic load, bending strength, surface durability, gear weight and size, and various geometric parameters. It is necessary to calculate all such important responses because they all represent competing requirements in the design process. The codes developed here were written in subroutine form and coupled to the COPES/ADS general purpose optimization program. This code allows the user to define the optimization problem at the time of program execution. Typical design variables include face width, number of teeth and diametral pitch. The user is free to choose any calculated response as the design objective to minimize or maximize and may impose lower and upper bounds on any calculated responses. Typical examples include life maximization with limits on dynamic load, stress, weight, etc. or minimization of weight subject to limits on life, dynamic load, etc. The research codes were written in modular form for easy expansion and so that they could be combined to create a multiple reduction optimization capability in future.

Vanderplaats, G. N.; Chen, Xiang; Zhang, Ning-Tian

1988-01-01

305

Geometrical characteristics of uniportal VATS  

PubMed Central

In terms of accuracy and efficacy Uniportal Video-Assisted Thoracic Surgery (VATS) resections are comparable to standard VATS. In standard three-ports VATS, the geometric configuration of a parallelogram generates interference with the optical source, creating a plane with a torsion angle not favorable on the flat two-dimensional vision of currently available monitors. The potential advantages of single-port VATS approach include not only the one intercostal space incision (reduction of postoperative pain) but also a translational approach of VATS instruments along a sagittal plane. Accordingly, the Uniportal approach enables VATS instruments to draw two parallel lines on the plane, bringing them to approach the target lesion from a caudo-cranial perspective thus achieving a projective plane. As a consequence, taking advantage of the unique spatial features specific to uniportal VATS, the surgeon is enabled to bring the operative fulcrum inside the chest to address the target lesion in a fashion similar to open surgery.

Rocco, Gaetano; Viti, Andrea; Terzi, Alberto

2013-01-01

306

Geometrical setting of solid mechanics  

SciTech Connect

Highlights: > Solid mechanics within the Riemannian symmetric manifold GL (3, R)/O (3, R). > Generalized logarithmic strain. > Consistent linearization. > Incremental principle of virtual power. > Time-discrete approximation. - Abstract: The starting point in the geometrical setting of solid mechanics is to represent deformation process of a solid body as a trajectory in a convenient space with Riemannian geometry, and then to use the corresponding tools for its analysis. Based on virtual power of internal stresses, we show that such a configuration space is the (globally) symmetric space of symmetric positive-definite real matrices. From this unifying point of view, we shall analyse the logarithmic strain, the stress rate, as well as linearization and intrinsic integration of corresponding evolution equation.

Fiala, Zdenek, E-mail: fiala@itam.cas.cz [Institute of Theoretical and Applied Mechanics, ASCR, v. v. i., Prosecka 809/76, 190 00 Praha 9 (Czech Republic)

2011-08-15

307

Geometric solitons of Hamiltonian flows on manifolds  

SciTech Connect

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.

Song, Chong, E-mail: songchong@xmu.edu.cn [School of Mathematical Sciences, Xiamen University, Xiamen 361005 (China)] [School of Mathematical Sciences, Xiamen University, Xiamen 361005 (China); Sun, Xiaowei, E-mail: sunxw@cufe.edu.cn [School of Applied Mathematics, Central University of Finance and Economics, Beijing 100081 (China)] [School of Applied Mathematics, Central University of Finance and Economics, Beijing 100081 (China); Wang, Youde, E-mail: wyd@math.ac.cn [Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China)] [Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China)

2013-12-15

308

Visible and near-IR spectroscopic studies of UC1{sub 4} in a basic ambient temperature melt: The observation of a possible geometric distorted UC1{sub 6}{sup 2{minus}} species and the evidence for the hydrogen-bond in the melt  

SciTech Connect

Since high temperatures can lead to broadening of absorption spectra, ambient temperature chloride melts were used; the system used was AlCl{sub 3}-1-ethyl-3-methyl-imidazolium chloride (EMIC). The uv-visible spectrum of UCl{sub 4} in basic melt had many peaks with the most intense (triplet) ones around 2000 nm, similar to these at high temperature and indicating the same species. The electronic transition is allowed by a static rather than a vibronic mechanism. The central peak in the UCl{sub 6}{sup 2-} spectrum indicates distortion of geometry from the O{sub h} symmetry by the solvent medium. Very strong hydrogen bonding between UCl{sub 6}{sup 2-} and solvent EMI is suggested.

Dai, S.; Toth, L.M.; Del Cul, G.D.; Metcalf, D.H.

1994-09-01

309

Geometric programming prediction of design trends for OMV protective structures  

NASA Technical Reports Server (NTRS)

The global optimization trends of protective honeycomb structural designs for spacecraft subject to hypervelocity meteroid and space debris are presented. This nonlinear problem is first formulated for weight minimization of the orbital maneuvering vehicle (OMV) using a generic monomial predictor. Five problem formulations are considered, each dependent on the selection of independent design variables. Each case is optimized by considering the dual geometric programming problem. The dual variables are solved for in terms of the generic estimated exponents of the monomial predictor. The primal variables are then solved for by conversion. Finally, parametric design trends are developed for ranges of the estimated regression parameters. Results specify nonmonotonic relationships for the optimal first and second sheet mass per unit areas in terms of the estimated exponents.

Mog, R. A.; Horn, J. R.

1990-01-01

310

Geometric Routing in Wireless Sensor Networks  

Microsoft Academic Search

\\u000a This chapter surveys routing algorithms for wireless sensor networks that use geometric ideas and abstractions. Wireless sensor\\u000a networks have a unique geometric character as the sensor nodes are embedded in, and designed to monitor, the physical space.\\u000a Thus the geometric embedding of the network can be exploited for scalable and efficient routing algorithm design. This chapter\\u000a starts with geographical routing

Jie Gao

311

Geometric Mathematical Framework for Multibody System Dynamics  

NASA Astrophysics Data System (ADS)

The paper surveys geometric mathematical framework for computational modeling of multibody system dynamics. Starting with the configuration space of rigid body motion and analysis of it's Lie group structure, the elements of respective Lie algebra are addressed and basic relations pertinent to geometrical formulations of multibody system dynamics are surveyed. Dynamical model of multibody system on manifold introduced, along with the outline of geometric characteristics of holonomic and non-holonomic kinematical constraints.

Terze, Zdravko; Vrdoljak, Milan; Zlatar, Dario

2010-09-01

312

Geometric phases in a scattering process  

SciTech Connect

The study of geometric phase in quantum mechanics has so far been confined to discrete (or continuous) spectra and trace-preserving evolutions. By considering only the transmission channel, a scattering process with internal degrees of freedom is neither a discrete spectrum problem nor a trace-preserving process. We explore the geometric phase in the scattering process by taking only the transmission process into account. We find that the geometric phase can be calculated by the same method as in unitary evolution. The interference visibility depends on the transmission amplitude. The dependence of the geometric phase on the barrier strength and the spin-spin coupling constant is also presented and discussed.

Liu, H. D.; Yi, X. X. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2011-08-15

313

Mathematical Optimization  

NSDL National Science Digital Library

Some of the most fundamental problems in engineering, science, and mathematics would take the most powerful computer in the world several lifetimes to find an optimal solution. However, near-optimal solutions to many of these problems have been discovered thanks to various methods of mathematical optimization. This Topic in Depth looks at some optimization techniques and the areas to which they have been applied.Argonne National Laboratory hosts an online guide (1) to some of the most well known optimization problems and algorithms. People who are new to the subject can find a wealth of introductory material in the Optimization Tree section, and several applications are illustrated with interactive demonstrations in the Case Studies section. Optimization has roots in operations research, and this tutorial (2) covers many topics within OR. A fun applet requires the user to place as many queens on a chess board as possible without any two being in direct line-of-sight, and an accompanying discussion shows how linear programming can be used to solve this problem; this is one of many resources contained within the tutorial. Two chemical engineering professors at Carnegie Mellon University are the authors of Retrospective on Optimization (3), a fairly comprehensive paper chronicling the history of optimization problems and the development of solution methods. The 51-page document is divided into two main parts; the first outlines some of the most significant advances in the field, and the second looks ahead toward key areas of research needed to evolve optimization further. Highway planning and development is the focus of this paper (4), which proposes using, among other things, genetic algorithms to optimize highway alignment. The authors state that this technique could be used to avoid delays and added costs due to changing plans later in the construction process. Another use of genetic algorithms in optimization is highlighted in this document from the German Aerospace Center (5). The document describes how a novel method for robot design, which involves formulating mathematical representations of robotic constraints and kinematics. These figures can then be used as parameters in a genetic algorithm that would optimize component placement while maintaining the desired functionality. A joint effort between architecture and mechanical engineering researchers at the University of Michigan (6) applied geometrical and topological optimization techniques to building floorplan layout. In the course of their research, they developed an optimization tool that is briefly described and can be downloaded from a Web site given in the paper. The Mathematical Programming Glossary (7) contains short discussions of hundreds of terms related to optimization theory. Each entry includes a clear definition and hyperlinks to other terms, and some of the entries are accompanied by a more in-depth supplement. One of the best sources for current research papers and reports is Optimization Online (8). This repository receives numerous submissions each month, and papers can be browsed by data added or category.

Leske, Cavin.

314

Weak bond screening system  

NASA Astrophysics Data System (ADS)

Consideration is given to the development of a weak bond screening system which is based on the utilization of a high power ultrasonic (HPU) technique. The instrumentation of the prototype bond strength screening system is described, and the adhesively bonded specimens used in the system developmental effort are detailed. Test results obtained from these specimens are presented in terms of bond strength and level of high power ultrasound irradiation. The following observations were made: (1) for Al/Al specimens, 2.6 sec of HPU irradiation will screen weak bond conditions due to improper preparation of bonding surfaces; (2) for composite/composite specimens, 2.0 sec of HPU irradiation will disrupt weak bonds due to under-cured conditions; (3) for Al honeycomb core with composite skin structure, 3.5 sec of HPU irradiation will disrupt weak bonds due to bad adhesive or oils contamination of bonding surfaces; and (4) for Nomex honeycomb with Al skin structure, 1.3 sec of HPU irradiation will disrupt weak bonds due to bad adhesive.

Chuang, S. Y.; Chang, F. H.; Bell, J. R.

315

Chemical bonding for precision optical assemblies  

NASA Astrophysics Data System (ADS)

We report on the optimization of precision optical component assemblies for space application with respect to mechanical resilience and retention of optical tolerances such as flatness and angles. Optimized parameters include: the cleaning method of the surfaces to be joined; type, concentration, and quantity of the chemical bonding agent; and post-bonding and curing conditions. Experimental studies and quality assurance are complicated by the large statistical spread in breaking stress, which requires the preparation of a large number of samples. The results previously reported in literature have focused primarily on fused silica, rather than space-qualifiable materials such as Zerodur® and ULE®, and have typically addressed only one or two of the parameters. This study provides a comprehensive picture and a better general understanding of what makes a bond reliably strong.

Green, Katie; Burke, Jan; Oreb, Bozenko

2011-02-01

316

Gaalop—High Performance Parallel Computing Based on Conformal Geometric Algebra  

NASA Astrophysics Data System (ADS)

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.

Hildenbrand, Dietmar; Pitt, Joachim; Koch, Andreas

317

Geometric Quantization and Foliation Reduction  

NASA Astrophysics Data System (ADS)

A standard question in the study of geometric quantization is whether symplectic reduction interacts nicely with the quantized theory, and in particular whether "quantization commutes with reduction." Guillemin and Sternberg first proposed this question, and answered it in the affirmative for the case of a free action of a compact Lie group on a compact Kahler manifold. Subsequent work has focused mainly on extending their proof to non-free actions and non-Kahler manifolds. For realistic physical examples, however, it is desirable to have a proof which also applies to non-compact symplectic manifolds. In this thesis we give a proof of the quantization-reduction problem for general symplectic manifolds. This is accomplished by working in a particular wavefunction representation, associated with a polarization that is in some sense compatible with reduction. While the polarized sections described by Guillemin and Sternberg are nonzero on a dense subset of the Kahler manifold, the ones considered here are distributional, having support only on regions of the phase space associated with certain quantized, or "admissible", values of momentum. We first propose a reduction procedure for the prequantum geometric structures that "covers" symplectic reduction, and demonstrate how both symplectic and prequantum reduction can be viewed as examples of foliation reduction. Consistency of prequantum reduction imposes the above-mentioned admissibility conditions on the quantized momenta, which can be seen as analogues of the Bohr-Wilson-Sommerfeld conditions for completely integrable systems. We then describe our reduction-compatible polarization, and demonstrate a one-to-one correspondence between polarized sections on the unreduced and reduced spaces. Finally, we describe a factorization of the reduced prequantum bundle, suggested by the structure of the underlying reduced symplectic manifold. This in turn induces a factorization of the space of polarized sections that agrees with its usual decomposition by irreducible representations, and so proves that quantization and reduction do indeed commute in this context. A significant omission from the proof is the construction of an inner product on the space of polarized sections, and a discussion of its behavior under reduction. In the concluding chapter of the thesis, we suggest some ideas for future work in this direction.

Skerritt, Paul

318

Bonded semiconductor substrate  

DOEpatents

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.

Atwater, Jr.; Harry A. (South Pasadena, CA), Zahler; James M. (Pasadena, CA)

2010-07-13

319

Energy pulse bonding  

NASA Technical Reports Server (NTRS)

To eliminate many of the present termination problems a technique called energy pulse bonding (EPB) was developed. The process demonstrated the capability of: (1) joining conductors without prior removal of insulations, (2) joining conductors without danger of brittle intermetallics, (3) increased joint temperature capability, (4) simultaneous formation of several bonds, (5) capability of higher joint density, and (6) a production oriented process. The following metals were successfully bonded in the solid state: copper, beryllium copper, phosphor bronze, aluminum, brass, and Kovar.

Smith, G. C.

1972-01-01

320

Chemical bonding technology  

NASA Technical Reports Server (NTRS)

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.

Plueddemann, E.

1986-01-01

321

Indirect bonding technique.  

PubMed

Accurate bracket placement is the key for the successful treatment of an orthodontic case. With indirect bonding, not only is the bracket placement more accurate but this technique also significantly reduces chairtime. In this article, the author explains use of thermal glue in an indirect bonding technique. In cases of constricted arches, a modified rapid maxillary expander can be used along with indirect bonding to reduce overall treatment time. PMID:17190232

Kothari, Ashok

2006-01-01

322

Teachers' Domain: Covalent Bonding  

NSDL National Science Digital Library

This Flash interactive tutorial explores covalent bonding, a type of chemical bond that involves sharing of electrons. Learners investigate the attractive and repulsive forces that act on atomic particles and how the sharing of electrons can keep atoms together. See how two hydrogen atoms interact with each other to create a covalent bond. Learn about patterns in the periodic table and how electrostatic potential energy determines the bond length. Teachers' Domain is a growing collection of more than 1,000 free educational resources compiled by researchers and experienced teachers to promote the use of digital resources in the classroom.

2011-08-16

323

Procedures for Shape Optimization of Gas Turbine Disks.  

National Technical Information Service (NTIS)

Two procedures, the feasible direction method and sequential linear programming, for shape optimization of gas turbine disks are presented. The objective of these procedures is to obtain optimal designs of turbine disks with geometric and stress constrain...

T. Cheu

1989-01-01

324

Geometrical aspects of quantum spaces  

SciTech Connect

Various geometrical aspects of quantum spaces are presented showing the possibility of building physics on quantum spaces. In the first chapter the authors give the motivations for studying noncommutative geometry and also review the definition of a Hopf algebra and some general features of the differential geometry on quantum groups and quantum planes. In Chapter 2 and Chapter 3 the noncommutative version of differential calculus, integration and complex structure are established for the quantum sphere S{sub 1}{sup 2} and the quantum complex projective space CP{sub q}(N), on which there are quantum group symmetries that are represented nonlinearly, and are respected by all the aforementioned structures. The braiding of S{sub q}{sup 2} and CP{sub q}(N) is also described. In Chapter 4 the quantum projective geometry over the quantum projective space CP{sub q}(N) is developed. Collinearity conditions, coplanarity conditions, intersections and anharmonic ratios is described. In Chapter 5 an algebraic formulation of Reimannian geometry on quantum spaces is presented where Riemannian metric, distance, Laplacian, connection, and curvature have their quantum counterparts. This attempt is also extended to complex manifolds. Examples include the quantum sphere, the complex quantum projective space and the two-sheeted space. The quantum group of general coordinate transformations on some quantum spaces is also given.

Ho, P.M. [Lawrence Berkeley Lab., CA (United States). Theoretical Physics Group

1996-05-11

325

Geometric reasoning about assembly tools  

SciTech Connect

Planning for assembly requires reasoning about various tools used by humans, robots, or other automation to manipulate, attach, and test parts and subassemblies. This paper presents a general framework to represent and reason about geometric accessibility issues for a wide variety of such assembly tools. Central to the framework is a use volume encoding a minimum space that must be free in an assembly state to apply a given tool, and placement constraints on where that volume must be placed relative to the parts on which the tool acts. Determining whether a tool can be applied in a given assembly state is then reduced to an instance of the FINDPLACE problem. In addition, the author presents more efficient methods to integrate the framework into assembly planning. For tools that are applied either before or after their target parts are mated, one method pre-processes a single tool application for all possible states of assembly of a product in polynomial time, reducing all later state-tool queries to evaluations of a simple expression. For tools applied after their target parts are mated, a complementary method guarantees polynomial-time assembly planning. The author presents a wide variety of tools that can be described adequately using the approach, and surveys tool catalogs to determine coverage of standard tools. Finally, the author describes an implementation of the approach in an assembly planning system and experiments with a library of over one hundred manual and robotic tools and several complex assemblies.

Wilson, R.H.

1997-01-01

326

Minkowski Geometric Algebra of Complex Sets  

Microsoft Academic Search

A geometric algebra of point sets in the complex plane is proposed, based on two fundamental operations: Minkowski sums and products. Although the (vector) Minkowski sum is widely known, the Minkowski product of two-dimensional sets (induced by the multiplication rule for complex numbers) has not previously attracted much attention. Many interesting applications, interpretations, and connections arise from the geometric algebra

Rida T. Farouki; Hwan Pyo Moon; Bahram Ravani

2001-01-01

327

Geometric Phases for Mixed States in Interferometry  

Microsoft Academic Search

We provide a physical prescription based on interferometry for introducing the total phase of a mixed state undergoing unitary evolution, which has been an elusive concept in the past. We define the parallel transport condition that provides a connection form for obtaining the geometric phase for mixed states. The expression for the geometric phase for mixed state reduces to well

Erik Sjöqvist; Arun K. Pati; Artur Ekert; Jeeva S. Anandan; Marie Ericsson; Daniel K. L. Oi; Vlatko Vedral

2000-01-01

328

Monotonicity and its analytic and geometric implications  

PubMed Central

In this expository article, we discuss various monotonicity formulas for parabolic and elliptic operators and explain how the analysis of function spaces and the geometry of the underlining spaces are intertwined. After briefly discussing some of the well-known analytical applications of monotonicity for parabolic operators, we turn to their elliptic counterparts, their geometric meaning, and some geometric consequences.

Colding, Tobias Holck; Minicozzi, William P.

2013-01-01

329

Parabolas: Connection between Algebraic and Geometrical Representations  

ERIC Educational Resources Information Center

A parabola is an interesting curve. What makes it interesting at the secondary school level is the fact that this curve is presented in both its contexts: algebraic and geometric. Being one of Apollonius' conic sections, the parabola is basically a geometric entity. It is, however, typically known for its algebraic characteristics, in particular…

Shriki, Atara

2011-01-01

330

Geometric Applications of Chernoff-Type Estimates  

Microsoft Academic Search

In this paper we present a probabilistic approach to some geometric problems in asymptotic convex geometry. The aim of this paper is to demonstrate that the well known Chernofi bounds from probability theory can be used in a geometric context for a very broad spectrum of problems, and lead to new and improved results. We begin by brie?y describing Chernofi

S. Artstein-Avidan; O. Friedland; Vitali Milman

331

Sensor alignment using rotors in Geometric Algebra  

Microsoft Academic Search

This paper uses rotors in Geometric Algebra to formulate a stable adaptive identifier on the group of rigid body rotations. This identifier is intended to estimate the alignment offsets between independent sensors. The approach provides a straightforward geometric interpretation based on first-order rotor kinematics. Lyapunov theory is used to prove the sta- bility of the identifier, and numerical simulations illustrate

M. Jordan Stanway; James C. Kinsey

2011-01-01

332

Early Sex Differences in Weighting Geometric Cues  

ERIC Educational Resources Information Center

When geometric and non-geometric information are both available for specifying location, men have been shown to rely more heavily on geometry compared to women. To shed insight on the nature and developmental origins of this sex difference, we examined how 18- to 24-month-olds represented the geometry of a surrounding (rectangular) space when…

Lourenco, Stella F.; Addy, Dede; Huttenlocher, Janellen; Fabian, Lydia

2011-01-01

333

Multivariate Statistical Analysis: A Geometric Perspective  

Microsoft Academic Search

A new, coordinate-free (geometric) approach to multivariate statistical analysis. General multivariate linear models and linear hypotheses are defined in geometric form. A method of constructing statistical criteria is defined for linear hypotheses. As a result, multivariate statistical analysis is developed in full analogy to classical statistical analysis. This approach is based on tensor products and modules over the ring of

Yuri N. Tyurin

2009-01-01

334

A Framework for Analyzing Geometric Pattern Tasks  

ERIC Educational Resources Information Center

Teachers can use geometric patterns to promote students' understanding of functional relationships. In this article, the authors first look at a problem-solving process that supports the use of figural reasoning to explore and interpret geometric pattern tasks and generalize function rules. Second, the authors discuss a framework for…

Friel, Susan N.; Markworth, Kimberly A.

2009-01-01

335

Geometrical and Operational Aspects of Irreversibility  

Microsoft Academic Search

In the statistical description of dynamical systems, an indication of the irreversibility of a given state change is given geometrically by means of a (pre-)ordering of state pairs. Reversible state changes of classical and quantum systems are shown to be represented by isometric state transformations. An operational distinction between reversible and irreversible dynamics is given and related to the geometric

P. Busch

1999-01-01

336

Hierarchical geometric models for visible surface algorithms  

Microsoft Academic Search

The geometric structure inherent in the definition of the shapes of three-dimensional objects and environments is used not just to define their relative motion and placement, but also to assist in solving many other problems of systems for producing pictures by computer. By using an extension of traditional structure information, or a geometric hierarchy, five significant improvements to current techniques

James H. Clark

1976-01-01

337

Mobile robot localization by tracking geometric beacons  

Microsoft Academic Search

The application of the extended Kaman filter to the problem of mobile robot navigation in a known environment is presented. An algorithm for, model-based localization that relies on the concept of a geometric beacon, a naturally occurring environment feature that can be reliably observed in successive sensor measurements and can be accurately described in terms of a concise geometric parameterization,

John J. Leonard; Hugh F. Durrant-Whyte

1991-01-01

338

Geometric phase in entangled bipartite systems  

NASA Astrophysics Data System (ADS)

The geometric phase (GP) for bipartite systems in transverse external magnetic fields is investigated in this paper. Two different situations have been studied. We first consider two non-interacting particles. The results show that because of entanglement, the geometric phase is very different from that of the non-entangled case. When the initial state is a Werner state, the geometric phase is, in general, zero and moreover the singularity of the geometric phase may appear with a proper evolution time. We next study the geometric phase when intra-couplings appear and choose Werner states as the initial states to entail this discussion. The results show that unlike our first case, the absolute value of the GP is not zero, and attains its maximum when the rescaled coupling constant J is less than 1. The effect of inhomogeneity of the magnetic field is also discussed.

Cui, H. T.; Wang, L. C.; Yi, X. X.

2007-02-01

339

Optimal Quantum Pumps  

NASA Astrophysics Data System (ADS)

We study adiabatic quantum pumps on time scales that are short relative to the cycle of the pump. In this regime the pump is characterized by the matrix of energy shift which we introduce as the dual to Wigner's time delay. The energy shift determines the charge transport, the dissipation, the noise, and the entropy production. We prove a general lower bound on dissipation in a quantum channel and define optimal pumps as those that saturate the bound. We give a geometric characterization of optimal pumps and show that they are noiseless and transport integral charge in a cycle. Finally we discuss an example of an optimal pump related to the Hall effect.

Avron, J. E.; Elgart, A.; Graf, G. M.; Sadun, L.

2001-12-01

340

How to improve forecasting with bred vectors by using the geometric norm  

NASA Astrophysics Data System (ADS)

The choice of the norm type (Euclidean, maximum, geometric,...) has a great impact on the construction of ensembles of bred vectors. In particular, using the geometric norm obtains a set of bred vectors, the so-called logarithmic bred vectors, with interesting properties. We have recently shown in [1] that among a spectrum of norms (including the Euclidean one) the geometric norm maximizes the statistical diversity of the ensemble while, at the same time, enhances the projection of the bred vectors on the linearly most unstable direction (the leading Lyapunov vector). Moreover, the geometric norm is also optimal in providing the least fluctuating ensemble dimension among the spectrum of norms considered. We carry out numerical experiments in the Lorenz-96 model assimilating noisy observations with a 3D-Var scheme. We compare the performance of forecasts using ensembles of bred vectors constructed with either the Euclidean norm or the geometric one. Our results, for several lead times and observational standard deviations, indicate that the geometric norm usually outperforms the Euclidean norm, in terms of root mean square error of the ensemble mean forecast. Finally, we give theoretical support to our results, which are expected to be generic for chaotic spatially extended systems. [1] D. Pazó, J. M. López, and M. A. Rodríguez, Maximizing the statistical diversity of an ensemble of bred vectors by using the geometric norm, J. Atmos. Sci. 68, 1507 (2011).

Pazó, D.; López, J. M.; Rodríguez, M. A.

2012-04-01

341

Mirror profile optimization for nano-focusing KB mirror  

NASA Astrophysics Data System (ADS)

A KB focusing mirror width profile has been optimized to achieve nano-focusing for the nano-imaging end-station ID22NI at the ESRF. The complete mirror and flexure bender assembly has been modeled in 3D with finite element analysis using ANSYS. Bender stiffness, anticlastic effects and geometrical non-linear effects have been considered. Various points have been studied: anisotropy and crystal orientation, stress in the mirror and bender, actuator resolution and the mirror-bender adhesive bonding... Extremely high performance of the mirror is expected with residual slope error smaller than 0.6 ?rad, peak-to-valley, compared to the bent slope of 3000 ?rad.

Zhang, Lin; Baker, Robert; Barrett, Ray; Cloetens, Peter; Dabin, Yves

2010-06-01

342

Mirror profile optimization for nano-focusing KB mirror  

SciTech Connect

A KB focusing mirror width profile has been optimized to achieve nano-focusing for the nano-imaging end-station ID22NI at the ESRF. The complete mirror and flexure bender assembly has been modeled in 3D with finite element analysis using ANSYS. Bender stiffness, anticlastic effects and geometrical non-linear effects have been considered. Various points have been studied: anisotropy and crystal orientation, stress in the mirror and bender, actuator resolution and the mirror-bender adhesive bonding... Extremely high performance of the mirror is expected with residual slope error smaller than 0.6 {mu}rad, peak-to-valley, compared to the bent slope of 3000 {mu}rad.

Zhang Lin; Baker, Robert; Barrett, Ray; Cloetens, Peter; Dabin, Yves [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France)

2010-06-23

343

Visionlearning: Chemical Bonding  

NSDL National Science Digital Library

This digital learning module provides an easily-understood overview of chemical bonding for users with little formal background in chemistry or physics. It explores ionic bonding through the example of sodium (an alkali metal) reacting with chlorine gas to produce common table salt. A concept simulation further illustrates the process.

Carpi, Anthony

2011-07-12

344

Interactive Pi Bonding Effects  

NSDL National Science Digital Library

This application demonstrates the effect of pi bonding on the one-electron ligand field splitting in an octahedral. By clicking on the appropriate buttons students can see how D changes when you move from ligands with no pi bonding capability to pi donor and pi acceptor ligands.

345

The dissociative bond.  

PubMed

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

Gordon, Nirit

2013-01-01

346

Chemical Bonds I  

ERIC Educational Resources Information Center

Chemical bonding is discussed from a bond energy, rather than a wave mechanics, viewpoint. This approach is considered to be more suitable for the average student. (The second part of the article will appear in a later issue of the journal.) (AL)

Sanderson, R. T.

1972-01-01

347

Mother-Child Bonding.  

ERIC Educational Resources Information Center

Examines the nature of mother-child bonding from the prenatal stage through early infancy, discussing how the mother's actions, even before birth, stimulate her child's senses. Explains the crucial role that physical contact, breastfeeding, and visual stimuli have on mother-child bonding in human and animal newborns. (MDM)

Pearce, Joseph Chilton

1994-01-01

348

The Sibling Bond.  

ERIC Educational Resources Information Center

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…

Bank, Stephen P.; Kahn, Michael D.

349

Excited-state intramolecular hydrogen bonding of compounds based on 2-(2-hydroxyphenyl)-1,3-benzoxazole in solution: A TDDFT study.  

PubMed

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?HO in 6 and 6a is demonstrated to be significantly strengthened, while NH?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. PMID:25000569

Li, Hui; Liu, Yufang; Yang, Yonggang; Yang, Dapeng; Sun, Jinfeng

2014-12-10

350

Molecular structure, Normal Coordinate Analysis, harmonic vibrational frequencies, Natural Bond Orbital, TD-DFT calculations and biological activity analysis of antioxidant drug 7-hydroxycoumarin  

NASA Astrophysics Data System (ADS)

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.

Sebastian, S.; Sylvestre, S.; Jayarajan, D.; Amalanathan, M.; Oudayakumar, K.; Gnanapoongothai, T.; Jayavarthanan, T.

2013-01-01

351

Optimal Design of Nonlinear Shell Structures.  

National Technical Information Service (NTIS)

A numerical method for optimal design of nonlinear shell structures is described. The nonlinearity is only geometrical and the external load is assumed to be conservative. The nonlinear shell is analyzed using standard shell finite elements with the displ...

U. T. Ringertz

1991-01-01

352

Enhancing wire-composite bond strength of bonded retainers with wire surface treatment.  

PubMed

Bonded orthodontic retainers with wires embedded in composite resin are commonly used for orthodontic retention. The purpose of this study was to test, in vitro, various wire surface treatments to determine the optimal method of enhancing the wire-composite bond strength. Coaxial wires and stainless steel wires with different surface treatments were bonded to bovine enamel and then pulled along their long axes with an Instron universal testing machine. Wire surface treatments included placing a right-angle bend in the wire, microetching the wire, and treating the wire with adhesion promoters; combinations of treatments were also examined. The results demonstrated a 24-fold increase in the wire-composite bond strength of wire that was microetched (sandblasted), compared with that of untreated straight wire. The difference between the amount of force required to break the bond produced by microetching alone (246.1 +/- 46.0 MPa) and that required for the bonds produced by the retentive bend (87.8 +/- 16.3 MPa), the adhesion promoters (silane, 11.0 +/- 3.1 MPa; Metal Primer, 28.5 +/- 15.8 MPa), or for any combination of surface treatments, was statistically significant. Microetching a stainless steel wire produced a higher wire-composite bond strength than that obtained from a coaxial wire (113.5 +/- 27.5 MPa). The results of this study indicate that microetching or sandblasting a stainless steel wire significantly increases the strength of the wire-composite bond. PMID:11395707

Oesterle, L J; Shellhart, W C; Henderson, S

2001-06-01

353

Shape Bonding method  

NASA Technical Reports Server (NTRS)

The present invention is directed to a method of bonding at least two surfaces together. The methods step of the present invention include applying a strip of adhesive to a first surface along a predefined outer boundary of a bond area and thereby defining a remaining open area there within. A second surface, or gusset plate, is affixed onto the adhesive before the adhesive cures. The strip of adhesive is allowed to cure and then a second amount of adhesive is applied to cover the remaining open area and substantially fill a void between said first and second surfaces about said bond area. A stencil may be used to precisely apply the strip of adhesive. When the strip cures, it acts as a dam to prevent overflow of the subsequent application of adhesive to undesired areas. The method results in a precise bond area free of undesired shapes and of a preferred profile which eliminate the drawbacks of the prior art bonds.

Pontius, James T. (Inventor)

2010-01-01

354

Technology of bonding elastomers  

NASA Astrophysics Data System (ADS)

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.

Symes, Ted; Oldfield, David

355

Wood Bond Testing  

NASA Technical Reports Server (NTRS)

A joint development program between Hartford Steam Boiler Inspection Technologies and The Weyerhaeuser Company resulted in an internal bond analyzer (IBA), a device which combines ultrasonics with acoustic emission testing techniques. It is actually a spinoff from a spinoff, stemming from a NASA Lewis invented acousto-ultrasonic technique that became a system for testing bond strength of composite materials. Hartford's parent company, Acoustic Emission Technology Corporation (AET) refined and commercialized the technology. The IBA builds on the original system and incorporates on-line process control systems. The IBA determines bond strength by measuring changes in pulsar ultrasonic waves injected into a board. Analysis of the wave determines the average internal bond strength for the panel. Results are displayed immediately. Using the system, a mill operator can adjust resin/wood proportion, reduce setup time and waste, produce internal bonds of a consistent quality and automatically mark deficient products.

1989-01-01

356

Ultrasonically bonded value assembly  

NASA Technical Reports Server (NTRS)

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.

Salvinski, R. J. (inventor)

1975-01-01

357

Effects of bridging hydrogens on metal-metal bonds. 1. Geometrical comparison of Fe/sub 3/(. mu. -H)/sub 3/(CO)/sub 9/(. mu. /sub 3/-CCH/sub 3/), Co/sub 3/(CO)/sub 9/ (. mu. /sub 3/-CCH/sub 3/), and model compounds  

SciTech Connect

The solid-state structure of Fe/sub 3/(..mu..-H)/sub 3/(CO)/sub 9/(..mu../sub 3/-CCH/sub 3/) (II) consists of a triangular M/sub 3/ base constructed of three Fe(CO)/sub 3/ fragments with hydrogens symmetrically bridging the M-M edges and with a C-CH/sub 3/ fragment symmetrically capping the metal triangle. The molecule has C/sub 3..nu../ symmetry, each iron being six-coordinate (three carbonyl ligands, two bridging hydrogens, and the methylidyne carbon) and the capping carbon four-coordinate (three irons and the methyl carbon). The comparison of the geometry of II with that of isoelectronic Co/sub 3/(CO)/sub 9/(..mu../sub 3/-CCH/sub 3/) (I) reveals several changes that are interpreted in terms of the bridging hydrogens acting as hydride-like ligands. It is demonstrated that the geometries of main-group model compounds for I and II (CH/sub 3/CC/sub 3/H/sub 3/ and CH/sub 3/CB/sub 3/H/sub 6/) as generated by ab initio calculations reproduce the structural differences of I and II. Hence, in I and II the representation of the Co(CO)/sub 3/ and Fe(CO)/sub 3/ fragments with CH and BH provides much more than a simple, descriptive analogy of the cluster bonding. Crystals of II form in the triclinic space group P anti 1 with the following unit cell parameters: a = 7.979 (2), b = 9.478 (3), c = 12.714 (4) A; ..cap alpha.. = 93.45 (3), ..beta.. = 106.94 (3), ..gamma.. = 60.79 (3)/sup 0/; V = 799 A/sup 3/; Z = 2. The x-ray structure was solved as described in the text and refined to R/sub 1/ = 0.076 and R/sub 2/ = 0.075 for 2496 independent reflections. 4 figures, 6 tables.

Wong, K.S. (Calvin Coll., Grand Rapids, MI); Haller, K.J.; Dutta, T.K.; Chipman, D.M.; Fehlner, T.P.

1982-08-01

358

Geometric frustration in compositionally modulated ferroelectrics.  

PubMed

Geometric frustration is a broad phenomenon that results from an intrinsic incompatibility between some fundamental interactions and the underlying lattice geometry. Geometric frustration gives rise to new fundamental phenomena and is known to yield intriguing effects such as the formation of exotic states like spin ice, spin liquids and spin glasses. It has also led to interesting findings of fractional charge quantization and magnetic monopoles. Mechanisms related to geometric frustration have been proposed to understand the origins of relaxor and multiferroic behaviour, colossal magnetocapacitive coupling, and unusual and novel mechanisms of high-transition-temperature superconductivity. Although geometric frustration has been particularly well studied in magnetic systems in the past 20 years or so, its manifestation in the important class formed by ferroelectric materials (which are compounds with electric rather than magnetic dipoles) is basically unknown. Here we show, using a technique based on first principles, that compositionally graded ferroelectrics possess the characteristic 'fingerprints' associated with geometric frustration. These systems have a highly degenerate energy surface and display critical phenomena. They further reveal exotic orderings with novel stripe phases involving complex spatial organization. These stripes display spiral states, topological defects and curvature. Compositionally graded ferroelectrics can thus be considered the 'missing link' that brings ferroelectrics into the broad category of materials able to exhibit geometric frustration. Our ab initio calculations allow deep microscopic insight into this novel geometrically frustrated system. PMID:21307851

Choudhury, Narayani; Walizer, Laura; Lisenkov, Sergey; Bellaiche, L

2011-02-24

359

Void-free wafer-level adhesive bonding utilizing modified poly (diallyl phthalate)  

NASA Astrophysics Data System (ADS)

A new thermosetting polymer, modified poly (diallyl phthalate) (PDAP), is used as intermediate layer to realize a void-free wafer-level transfer bonding, in which the bonding interface contains patterned metal. Through glass-silicon bonding experiments, bonding defects are easily recognized with light microscopy. Three typical defect types are identified as: uneven flow defect, particle defect and bubble defect. The processing parameters, such as bonding pressure, pre-baking temperature, polymer thickness and coating conditions, have been optimized based on analysis of the defect formation. The optimized conditions have yielded a void-free wafer-level adhesive bonding. Then, the die shearing test indicates a good bonding strength. Additionally, the transfer bonding process is applied in SOI-silicon bonding as a practical example of MEMS fabrication.

Zhong, Fang; Dong, Tao; Yong, He; Yan, Su; Wang, Kaiying

2013-12-01

360

Recognition of Watson-Crick base pairs: constraints and limits due to geometric selection and tautomerism  

PubMed Central

The natural bases of nucleic acids have a strong preference for one tautomer form, guaranteeing fidelity in their hydrogen bonding potential. However, base pairs observed in recent crystal structures of polymerases and ribosomes are best explained by an alternative base tautomer, leading to the formation of base pairs with Watson-Crick-like geometries. These observations set limits to geometric selection in molecular recognition of complementary Watson-Crick pairs for fidelity in replication and translation processes.

Yusupov, Marat; Yusupova, Gulnara

2014-01-01

361

Strain effect in determining the geometric shape of self-assembled quantum dot  

Microsoft Academic Search

The geometric shape of a self-assembled quantum dot (QD) formed by the strain-induced Stranski-Krastanov mode has been studied as a function of strain energy by the short-range valence-force-field approach. It has been shown by dynamic bond relaxation through strain energy minimization that for the most commonly used InAs QD in GaAs and InP matrices and Ge QD in Si matrix,

X.-F. Yang; K. Fu; W. Lu; W.-L. Xu; Y. Fu

2009-01-01

362

On a Geometric Approach to the Segment Sum Problem and Its Generalization  

Microsoft Academic Search

Given a sequence of n real numbers a1;a2;a3;:::;an, the maximum segment sum problem is that of determin- ing indices i and j (1 • ijn) such that the sum s(i;j) = ai + ai+1 + ::: + aj is a maximum. Monotone matrices were shown to be remarkably efiective in solv- ing several geometric optimization problems. The sur- prise is

Asish Mukhopadhyay; Eugene Greene

2007-01-01

363

A common algorithm for various parametric geometric changes in finite element design sensitivity computation  

Microsoft Academic Search

Design sensitivity analysis is mainly applicable to optimization and force computation problems. With the former, geometrical parameters undergo big changes that require mesh integrity checks and mesh connections need to be preserved for C1 continuity. This is usually addressed through problem-specific mesh generators that cannot be general purpose. This paper presents a new criterion for changing meshes for design sensitivity

S. Krishnakumar; S. R. H. Hoole

2005-01-01

364

Diffusion Bonding of Silicon Carbide for MEMS-LDI Applications  

NASA Technical Reports Server (NTRS)

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.

Halbig, Michael C.; Singh, Mrityunjay; Shpargel, Tarah P.; Kiser, J. Douglas

2007-01-01

365

A new decomposition strategy for parallel bonded molecular dynamics  

SciTech Connect

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.

Plimpton, S.; Hendrickson, B.; Heffelfinger, G.

1992-12-31

366

Ultrasonic friction power during Al wire wedge-wedge bonding  

NASA Astrophysics Data System (ADS)

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 222 nm. The maximum interfacial friction power is at least 11.5 mW, which is only about 4.8% of the total electrical power delivered to the ultrasonic generator.

Shah, A.; Gaul, H.; Schneider-Ramelow, M.; Reichl, H.; Mayer, M.; Zhou, Y.

2009-07-01

367

Geometric phases in open tripod systems  

SciTech Connect

We first consider stimulated Raman adiabatic passages in a closed four-level tripod system. In this case, the adiabatic eigenstates of the system acquire real geometric phases. When the system is open and subject to decoherence they acquire complex geometric phases that we determine by a Monte Carlo wave function approach. We calculate the geometric phases and the state evolution in the closed as well as in the open system cases and describe the deviation between these in terms of the phases acquired. When the system is closed, the adiabatic evolution implements a Hadamard gate. The open system implements an imperfect gate and hence has a fidelity below unity. We express this fidelity in terms of the acquired geometric phases.

Moeller, Ditte; Madsen, Lars Bojer; Moelmer, Klaus [Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, University of Aarhus, DK-8000 (Denmark)

2008-02-15

368

Geometric phases in open tripod systems  

NASA Astrophysics Data System (ADS)

We first consider stimulated Raman adiabatic passages in a closed four-level tripod system. In this case, the adiabatic eigenstates of the system acquire real geometric phases. When the system is open and subject to decoherence they acquire complex geometric phases that we determine by a Monte Carlo wave function approach. We calculate the geometric phases and the state evolution in the closed as well as in the open system cases and describe the deviation between these in terms of the phases acquired. When the system is closed, the adiabatic evolution implements a Hadamard gate. The open system implements an imperfect gate and hence has a fidelity below unity. We express this fidelity in terms of the acquired geometric phases.

Møller, Ditte; Madsen, Lars Bojer; Mølmer, Klaus

2008-02-01

369

The Pentagon Problem: Geometric Reasoning with Technology.  

ERIC Educational Resources Information Center

Presents an activity, involving pentagons and using a figure manipulator such as The Geometer's Sketchpad, that requires students to reason geometrically without making unsubstantiated assumptions based on diagrams. (MKR)

Zbiek, Rose Mary

1996-01-01

370

Experimental determination of cluster geometrical structure.  

National Technical Information Service (NTIS)

Chemical probes have been developed to provide insight into the geometrical structure of isolated transition metal clusters. By determining as a function of cluster size the number of adsorbate molecules that saturate a cluster, and/or the binding energy ...

S. J. Riley

1995-01-01

371

A Geometric Approach to Burgers' Riccati Equation.  

National Technical Information Service (NTIS)

The directrix approach, which gives powerful insight to the geometric structure of solutions of the general Riccati equation, is developed. Burgers' Riccati equation is derived, and conclusions are drawn using the directrix approach concerning the bounded...

G. L. Gallagher

1970-01-01

372

Transport Properties of Biofluids in Micromachined Geometrics.  

National Technical Information Service (NTIS)

The determination of transport properties of biological materials flowing in micron and sub-micron geometrics is discussed. The program goal was to develop techniques to identify anomalous viscous and diffusion effects due to complex biological materials....

K. Breuer

2002-01-01

373

Geometrically Frustrated Magnets as Model Systems.  

National Technical Information Service (NTIS)

The specific aim of this research program is to understand the cooperative magnetic properties of geometrically frustrated magnets which are model systems for the general phenomena of frustration. In the past year, we have continued studies of the dynamic...

P. Schiffer

2004-01-01

374

Geometric singular perturbation theory in biological practice  

Microsoft Academic Search

Geometric singular perturbation theory is a useful tool in the analysis of problems with a clear separation in time scales.\\u000a It uses invariant manifolds in phase space in order to understand the global structure of the phase space or to construct\\u000a orbits with desired properties. This paper explains and explores geometric singular perturbation theory and its use in (biological)\\u000a practice.

Geertje Hek

2010-01-01

375

Multivariate Statistical Analysis: A Geometric Perspective  

Microsoft Academic Search

A new, coordinate-free (geometric) approach to multivariate statistical\\u000aanalysis. General multivariate linear models and linear hypotheses are defined\\u000ain geometric form. A method of constructing statistical criteria is defined for\\u000alinear hypotheses. As a result, multivariate statistical analysis is developed\\u000ain full analogy to classical statistical analysis. This approach is based on\\u000atensor products and modules over the ring of

Yuri N. Tyurin

2009-01-01

376

The geometrical framework for Yang Mills theories  

Microsoft Academic Search

We construct a new geometrical framework for Yang-Mills Lagrangian field theories as an appropriate quotient space of the standard first jet-bundle and investigate the geometrical properties of the resulting mathematical setting. We deduce the field equations from a variational problem formulated through a regular Poincaré-Cartan form, thus ensuring the kinematical admissibility of critical sections. We state a generalized Nöther theorem

Roberto Cianci; Stefano Vignolo; Danilo Bruno

2003-01-01

377

Diversity and feasibility of direct bonding: a survey of a dedicated optical technology.  

PubMed

The aim of this paper is to review almost a decade of direct-bonding activities at Philips Research including the diversity and feasibility of direct bonding. The bondability of a material is determined by its geometrical shape and mechanical, physical, and chemical surface states. Physically direct bonding provides a vacuumtight bond, which is jointless and glueless, and it permits engineering of the interfaces to be bonded. Layers can be buried, and reflective-lossless bonds between optical elements can be created. A variety of materials are investigated: (refractory) metals, a semimetal, boron, diamond, a carbide, fluorides, nitrides, oxides, and a chalcogenide. The applications that we describe relate to interface engineering, waveguiding, and the direct bonding of a fiber plate. PMID:20862132

Haisma, J; Spierings, B A; Biermann, U K; van Gorkum, A A

1994-03-01

378

Geometrically invariant watermarking using feature points.  

PubMed

This paper presents a new approach for watermarking of digital images providing robustness to geometrical distortions. The weaknesses of classical watermarking methods to geometrical distortions are outlined first. Geometrical distortions can be decomposed into two classes: global transformations such as rotations and translations and local transformations such as the StirMark attack. An overview of existing self-synchronizing schemes is then presented. Theses schemes can use periodical properties of the mark, invariant properties of transforms, template insertion, or information provided by the original image to counter geometrical distortions. Thereafter, a new class of watermarking schemes using the image content is presented. We propose an embedding and detection scheme where the mark is bound with a content descriptor defined by salient points. Three different types of feature points are studied and their robustness to geometrical transformations is evaluated to develop an enhanced detector. The embedding of the signature is done by extracting feature points of the image and performing a Delaunay tessellation on the set of points. The mark is embedded using a classical additive scheme inside each triangle of the tessellation. The detection is done using correlation properties on the different triangles. The performance of the presented scheme is evaluated after JPEG compression, geometrical attack and transformations. Results show that the fact that the scheme is robust to these different manipulations. Finally, in our concluding remarks, we analyze the different perspectives of such content-based watermarking scheme. PMID:18249723

Bas, Patrick; Chassery, Jean-Marc; Macq, Benoît

2002-01-01

379

Bonding aerogels with polyurethanes  

SciTech Connect

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.

Matthews, F.M.; Hoffman, D.M.

1989-11-01

380

Strained-Bond Semiconductors.  

National Technical Information Service (NTIS)

Theories of strained-bond semiconductors and superconductors have been developed that promise to have significant impact on future electronic devices of interest to the Air Force. These include: (a) development of a theory of high-temperature superconduct...

J. D. Dow

1994-01-01

381

Covalency in the f-element–chalcogen bond  

Microsoft Academic Search

The geometric and electronic structures of the title complexes have been studied using gradient corrected density functional theory. Excellent agreement is observed between computed r(M–E) and experimental values in analogous Pri complexes. Natural charge analysis indicates that the M–E bond becomes less ionic in the order O>S>S> Te, and that this decrease is largest for U and smallest for La.

Kieran I. M. Ingram; Nikolas Kaltsoyannis; Andrew J. Gaunt; Mary P. Neu

2007-01-01

382

All about Chemical Bonding  

NSDL National Science Digital Library

Stephen Lower, a retired professor at Simon Fraser University, created this expansive and instructive website as a supplement to formal chemistry education for undergraduate students. Visitors will find in-depth descriptions along with several diagrams dealing with chemical bonding issues including their properties, shared-electron covalent bonds, hybrid orbitals, coordination complexes, and metals and semiconductors. General chemistry students looking for assistance should visit this well-developed educational site.

Lower, Stephen

383

Alloyed Thick Film Gold Conductor for High-Reliability High-Yield Wire Bonding  

Microsoft Academic Search

The widespread use of ultrasonic aluminum wire bonding and the increasing use of automatic thermosonic gold wire bonding in thick-film hybrid microelectronic circuitry has prompted the develolpment of materials optimized for these specialized bonding techniques. A new reduced thickness (\\

SAMUEL J. HOROWITZ; JOHN J. FELTEN; DONALD J. GERRY

1979-01-01

384

Diffusion Bonding of Silicon Carbide Ceramics using Titanium Interlayers  

NASA Technical Reports Server (NTRS)

Robust joining approaches for silicon carbide ceramics are critically needed to fabricate leak free joints with high temperature mechanical capability. In this study, titanium foils and physical vapor deposited (PVD) titanium coatings were used to form diffusion bonds between SiC ceramics using hot pressing. Silicon carbide substrate materials used for bonding include sintered SiC and two types of CVD SiC. Microscopy results show the formation of well adhered diffusion bonds. The bond strengths as determined from pull tests are on the order of several ksi, which is much higher than required for a proposed application. Microprobe results show the distribution of silicon, carbon, titanium, and other minor elements across the diffusion bond. Compositions of several phases formed in the joint region were identified. Potential issues of material compatibility and optimal bond formation will also be discussed.

Halbig, Michael C.; Singh, Mrityunjay; Shpargel, Tarah P.; Kiser, James D.

2006-01-01

385

Double-bond defect modelling in As-S glasses  

NASA Astrophysics Data System (ADS)

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.

Boyko, V.; Shpotyuk, O.; Hyla, M.

2010-11-01

386

Correlation Between Bond Reliability and Solid Phase Bonding Techniques for Contaminated Bonding Surfaces.  

National Technical Information Service (NTIS)

The relationship between bond reliability and the solid phase bonding technique used to interconnect on contaminated substrates has been investigated. Hybrid microcircuit substrates were contaminated with Shipley 1350H photoresist. Solid phase bonds on th...

D. W. Bushmire P. H. Holloway

1975-01-01

387

Geometric effects on stress wave propagation.  

PubMed

The present study, through finite element simulations, shows the geometric effects of a bioinspired solid on pressure and impulse mitigation for an elastic, plastic, and viscoelastic material. Because of the bioinspired geometries, stress wave mitigation became apparent in a nonintuitive manner such that potential real-world applications in human protective gear designs are realizable. In nature, there are several toroidal designs that are employed for mitigating stress waves; examples include the hyoid bone on the back of a woodpecker's jaw that extends around the skull to its nose and a ram's horn. This study evaluates four different geometries with the same length and same initial cross-sectional diameter at the impact location in three-dimensional finite element analyses. The geometries in increasing complexity were the following: (1) a round cylinder, (2) a round cylinder that was tapered to a point, (3) a round cylinder that was spiraled in a two dimensional plane, and (4) a round cylinder that was tapered and spiraled in a two-dimensional plane. The results show that the tapered spiral geometry mitigated the greatest amount of pressure and impulse (approximately 98% mitigation) when compared to the cylinder regardless of material type (elastic, plastic, and viscoelastic) and regardless of input pressure signature. The specimen taper effectively mitigated the stress wave as a result of uniaxial deformational processes and an induced shear that arose from its geometry. Due to the decreasing cross-sectional area arising from the taper, the local uniaxial and shear stresses increased along the specimen length. The spiral induced even greater shear stresses that help mitigate the stress wave and also induced transverse displacements at the tip such that minimal wave reflections occurred. This phenomenon arose although only longitudinal waves were introduced as the initial boundary condition (BC). In nature, when shearing occurs within or between materials (friction), dissipation usually results helping the mitigation of the stress wave and is illustrated in this study with the taper and spiral geometries. The combined taper and spiral optimized stress wave mitigation in terms of the pressure and impulse; thus providing insight into the ram's horn design and woodpecker hyoid designs found in nature. PMID:24362893

Johnson, K L; Trim, M W; Horstemeyer, M F; Lee, N; Williams, L N; Liao, J; Rhee, H; Prabhu, R

2014-02-01

388

Physical understanding through variational reasoning: electron sharing and covalent bonding.  

PubMed

Energy changes of stationary states resulting from geometric parameter changes in the Hamiltonian can be understood by variational reasoning in terms of the physical attributes of the kinetic and the potential energy functionals. In atoms as well as molecules, the energy minimization determines the ground state as the optimal compromise between the potential pull of the nuclear attractions and the localization-resisting kinetic pressure of the electron cloud. This variational competition is analyzed for the exact ab initio ground-state wave function of the hydrogen molecule ion to elucidate the formation of the bond. Its electronic wave function is shown to differ from the ground-state wave function of the hydrogen atom by polarization, sharing, and contraction, and the corresponding contributions to the binding energy are examined in detail. All told, the critical feature is that a molecular orbital, contracting (in the variational context) toward two nuclei simultaneously, can lower its potential energy while maintaining a certain degree of delocalization. As a consequence, its kinetic energy functional has a lower value than that of an orbital contracting toward a single nucleus equally closely. By contrast, the potential energy functional is lowered equally effectively whether the orbital contracts toward one nucleus or simultaneously toward two nuclei. Because of this weaker kinetic energy pressure, the electrostatic potential pull of the nuclei in the molecule is able to attach the orbital more tightly to each of the nuclei than the pull of the single nucleus in the atom is able to do. The role of the virial theorem is clarified. Generalizations to other molecules are discussed. PMID:19228050

Ruedenberg, Klaus; Schmidt, Michael W

2009-03-12

389

Modeling and characterization of the bonding-wire interconnection for microwave MCM  

Microsoft Academic Search

The 3-D electromagnetic software Ansoft HFSS is adapted to modeling analysis and simulation optimization about the microwave characteristics of bonding interconnection in the MMCM. The gold bond model contained micro strip is set up to emulate and optimize for insertion loss (IL) and return loss (RL), according to the major parameters such as arch highness, span and the root of

Liang Ying; Huang ChunYue; Wang Wangang

2010-01-01

390

Optimizing Electrostatic Field Calculations with the Adaptive Poisson-Boltzmann Solver to Predict Electric Fields at Protein-Protein Interfaces II: Explicit Near-Probe and Hydrogen-Bonding Water Molecules.  

PubMed

We have examined the effects of including explicit, near-probe solvent molecules in a continuum electrostatics strategy using the linear Poisson-Boltzmann equation with the Adaptive Poisson-Boltzmann Solver (APBS) to calculate electric fields at the midpoint of a nitrile bond both at the surface of a monomeric protein and when docked at a protein-protein interface. Results were compared to experimental vibrational absorption energy measurements of the nitrile oscillator. We examined three methods for selecting explicit water molecules: (1) all water molecules within 5 Å of the nitrile nitrogen; (2) the water molecule closest to the nitrile nitrogen; and (3) any single water molecule hydrogen-bonding to the nitrile. The correlation between absolute field strengths with experimental absorption energies were calculated and it was observed that method 1 was only an improvement for the monomer calculations, while methods 2 and 3 were not significantly different from the purely implicit solvent calculations for all protein systems examined. Upon taking the difference in calculated electrostatic fields and comparing to the difference in absorption frequencies, we typically observed an increase in experimental correlation for all methods, with method 1 showing the largest gain, likely due to the improved absolute monomer correlations using that method. These results suggest that, unlike with quantum mechanical methods, when calculating absolute fields using entirely classical models, implicit solvent is typically sufficient and additional work to identify hydrogen-bonding or nearest waters does not significantly impact the results. Although we observed that a sphere of solvent near the field of interest improved results for relative field calculations, it should not be consider a panacea for all situations. PMID:24446740

Ritchie, Andrew W; Webb, Lauren J

2014-07-17

391

Who Should Buy Long-Term Bonds?  

Microsoft Academic Search

According to conventional wisdom, long-term bonds are appropriate for conservative long-term investors. This paper develops a model of optimal consumption and portfolio choice for infinite-lived investors with recursive utility who face stochastic interest rates, solves the model using an approximate analytical method, and evaluates conventional wisdom. As risk aversion increases, the myopic component of risky asset demand disappears but the

John Y. Campbell; Luis M. Viceira

2001-01-01

392

Fluxless eutectic bonding of GaAs-on-Si by using Ag/Sn solder  

NASA Astrophysics Data System (ADS)

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.

Eo, Sung-Hwa; Kim, Dae-Seon; Jeong, Ho-Jung; Jang, Jae-Hyung

2013-11-01

393

Geometric isotope effects on small chloride ion water clusters with path integral molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

The geometric isotope effects on the structures of hydrated chloride ionic hydrogen bonded clusters are explored by carrying out path integral molecular dynamics simulations. First, an outer shell coordinate is selected to display the rearrangement of single and multi hydration shell cluster structures. Next, to show the competition of intramolecular and intermolecular nuclear quantum effects, the intramolecular OH? stretching and intermolecular ion-water wagging motions are studied for single and multi shell structures, respectively. The results indicate that the intermolecular nuclear quantum effects stabilize the ionic hydrogen bonds in single shell structures, while they are destabilized through the competition with intramolecular nuclear quantum effects in multi shell structures. In addition, the correlations between ion-water stretching motion and other cluster vibrational coordinates are discussed. The results indicate that the intermolecular nuclear quantum effects on the cluster structures are strongly related to the cooperation of the water-water hydrogen bond interactions.

Wang, Qi; Suzuki, Kimichi; Nagashima, Umpei; Tachikawa, Masanori; Yan, Shiwei

2013-11-01

394

Adaptive Shape Optimization Method  

Microsoft Academic Search

The principal objective of this work is to introduce an adaptive strategy to monitor the convergence rate of a Newton-like\\u000a method in shape optimization. Shape optimization problems are characterized by a cost function and a partial differential\\u000a equation (P.D.E.) which depend both of the geometrical domain. Typically we want to compute a shape * such that \\u000a \\u000a \\u000a \\u000a \\u000a W<\\/font\\u000a>* = argmin{

Jean R. Roche

395

Adhesive for composite bonding  

SciTech Connect

Adhesive bonding is a viable option for structural joining of carbon fiber reinforced epoxy composites. Recent examples from laboratory programs include a composite tube joined to a flared composite collar (skirt) to provide a means for mechanical attachment. Another application involves adhesive bonding of a close-tolerance composite ring to the inside of a tapered, cylindrical composite penetrator case in order to provide a load bearing surface for prestressing the internal package. The adhesive bond in both of these applications is the critical load bearing component and must sustain large shearing stresses in order to maintain the structural integrity and viability of the part. The ideal adhesive would be a low viscosity (<10 poise) liquid with a long pot life, good wetting characteristics and high ultimate shear strength when cured at moderate (<50{degree}C) temperature. An adhesive with these characteristics would allow for the production of defect-free bonds by capillary wetting or squeezing flow of the adhesive into the narrow (.005{double prime}) annular space between the concentric composite parts. Since adhesives possessing these characteristics were not known to be available commercially, candidate materials were evaluated for this application. In this paper we present bond shear strength data and selected physical properties for some epoxy adhesive formulations. 7 refs., 5 figs., 2 tabs.

Lyon, R.E.; Walkup, C.M.; Matthews, J.T.

1989-11-27

396

Strength of Chemical Bonds  

NASA Technical Reports Server (NTRS)

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.

Christian, Jerry D.

1973-01-01

397

Insect sex pheromones: minor amount of opposite geometrical isomer critical to attraction.  

PubMed

(Z)-II-Tetradecenyl acetate is the reported sex pheromone of European corn borer and redbanded leafroller moths. However, geometrically pure preparations of the compound are weakly attractive to these species. Presence of the E geometrical isomer in the Z is necessary for maximum sex attraction and these moths are "tuned" to respond optimally to specific proportions of Z to E. This discovery is important to considerations of moth pheromonal specificity, evolution, and in application of knowledge of the pheromones to insect-pest suppression. PMID:17736980

Klun, J A; Chapman, O L; Mattes, K C; Wojtkowski, P W; Beroza, M; Sonnet, P E

1973-08-17

398

Fundamentals of fiber bonding in thermally point-bonded nonwovens  

NASA Astrophysics Data System (ADS)

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.

Chidambaram, Aparna

399

Control Chart Tests Based on Geometric Moving Averages  

Microsoft Academic Search

A geometrical moving average gives the most recent observation the greatest weight, and all previous observations weights decreasing in geometric progression from the most recent back to the first. A graphical procedure for generating geometric moving averages is described in which the most recent observation is assigned a weight r. The properties of control chart tests based on geometric moving

S. W. Roberts

1959-01-01

400

Surface analysis in composite bonding  

NASA Technical Reports Server (NTRS)

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.

Messick, D. L.; Wightman, J. P.

1982-01-01

401

The effect of photometric and geometric context on photometric and geometric lightness effects  

PubMed Central

We measured the lightness of probe tabs embedded at different orientations in various contextual images presented on a computer-controlled stereo display. Two background context planes met along a horizontal roof-like ridge. Each plane was a graphic rendering of a set of achromatic surfaces with the simulated illumination for each plane controlled independently. Photometric context was varied by changing the difference in simulated illumination intensity between the two background planes. Geometric context was varied by changing the angle between them. We parsed the data into separate photometric effects and geometric effects. For fixed geometry, varying photometric context led to linear changes in both the photometric and geometric effects. Varying geometric context did not produce a statistically reliable change in either the photometric or geometric effects.

Lee, Thomas Y.; Brainard, David H.

2014-01-01

402

Overview on METEOSAT geometrical image data processing  

NASA Technical Reports Server (NTRS)

Digital Images acquired from the geostationary METEOSAT satellites are processed and disseminated at ESA's European Space Operations Centre in Darmstadt, Germany. Their scientific value is mainly dependent on their radiometric quality and geometric stability. This paper will give an overview on the image processing activities performed at ESOC, concentrating on the geometrical restoration and quality evaluation. The performance of the rectification process for the various satellites over the past years will be presented and the impacts of external events as for instance the Pinatubo eruption in 1991 will be explained. Special developments both in hard and software, necessary to cope with demanding tasks as new image resampling or to correct for spacecraft anomalies, are presented as well. The rotating lens of MET-5 causing severe geometrical image distortions is an example for the latter.

Diekmann, Frank J.

1994-01-01

403

Adhesive bond degradation sensor  

NASA Astrophysics Data System (ADS)

Early detection of adhesive bond degradation using sensing elements embedded within the 100um bond-line of aluminium epoxy adhesive joints has been demonstrated. Sensing elements of varying heights were fabricated at the ends of narrow conductors on a flexi-circuit carrier. This construction simulates the active sensing region on a patented silicon adhesive bond degradation sensor and has been used to characterize the sensing elements without the expense and time associated with fabricating the complete integrated silicon sensor. The highest elements on the flexi-circuit serve both as electrical pickup studs, providing a circuit from the flexi-circuit to the top aluminium plate, and as spacers to ensure that the shorter sensing elements do not contact the aluminium plate. The non-contacting sensing elements are thus arranged to be close to the metal/adhesive interface and are sensitive to any change in conductivity in this region due to release of ions as the interface is degraded by the environment. Accelerated aging tests were performed on flexi-circuit sensors embedded in the bond-line of double cantilever beam specimens. The specimens were immersed in 50° C water and pre-loaded to just initiate a crack. Load on the specimen was then maintained by applying a constant load point displacement with a very low velocity to ensure that the environment would degrade the bond-line in advance of the crack front. The change of load and the conductivity measured by the sensing elements were then logged with time. The onset of bond degradation was detected approximately 10-20 mm ahead of the crack tip.

Wilson, Alan R.; Olsson-Jacques, Christina; Muscat, Richard F.

2002-12-01

404

Influence of transition metal coordination on halogen bonding: CSD survey and theoretical study  

NASA Astrophysics Data System (ADS)

Density functional theory calculations at the level of M06 have been carried out to investigate the influence of transition metal coordinate on halogen bonding. It was found that the introduction of coordination forces leads to much stronger halogen bonds. This effect has been analyzed in detail by the geometric, energetic, electrostatic potential, and AIM properties of the complexes. In addition, some crystal structures extracted from the Cambridge Structural Database were selected to provide experimental evidence of the combination of the two interactions.

Wang, Yanhua; Wu, Weihong; Liu, Yingtao; Lu, Yunxiang

2013-07-01

405

Bonding, structure, and magnetism of physisorbed and chemisorbed O2 on Pt(111)  

Microsoft Academic Search

Near-edge x-ray-absorption fine-structure spectroscopy studies are used to determine changes in the electronic, geometric, and magnetic structure of two sequential molecular precursors of O2 on Pt(111). Both molecules lie down on the surface. Physisorbed O2 is found to be van der Waals bonded, structurally unperturbed and paramagnetic, while chemisorbed O2 is pi bonded, stretched by 0.16 Å, and exhibits a

W. Wurth; J. Stöhr; P. Feulner; X. Pan; K. R. Bauchspiess; Y. Baba; E. Hudel; G. Rocker; D. Menzel

1990-01-01

406

Model-based vision using geometric hashing  

NASA Astrophysics Data System (ADS)

The Geometric Hashing technique developed by the NYU Courant Institute has been applied to various automatic target recognition applications. In particular, I-MATH has extended the hashing algorithm to perform automatic target recognition ofsynthetic aperture radar (SAR) imagery. For this application, the hashing is performed upon the geometric locations of dominant scatterers. In addition to being a robust model-based matching algorithm -- invariant under translation, scale, and 3D rotations of the target -- hashing is of particular utility because it can still perform effective matching when the target is partially obscured. Moreover, hashing is very amenable to a SIMD parallel processing architecture, and thus potentially realtime implementable.

Akerman, Alexander, III; Patton, Ronald

1991-04-01

407

Geometric accuracy in airborne SAR images  

NASA Technical Reports Server (NTRS)

Uncorrected across-track motions of a synthetic aperture radar (SAR) platform can cause both a severe loss of azimuthal positioning accuracy in, and defocusing of, the resultant SAR image. It is shown how the results of an autofocus procedure can be incorporated in the azimuth processing to produce a fully focused image that is geometrically accurate in azimuth. Range positioning accuracy is also discussed, leading to a comprehensive treatment of all aspects of geometric accuracy. The system considered is an X-band SAR.

Blacknell, D.; Quegan, S.; Ward, I. A.; Freeman, A.; Finley, I. P.

1989-01-01

408

Geometric Analysis of Alloreactive HLA ?-Helices  

PubMed Central

Molecular dynamics (MD) is a valuable tool for the investigation of functional elements in biomolecules, providing information on dynamic properties and processes. Previous work by our group has characterized static geometric properties of the two MHC ?-helices comprising the peptide binding region recognized by T cells. We build upon this work and used several spline models to approximate the overall shape of MHC ?-helices. We applied this technique to a series of MD simulations of alloreactive MHC molecules that allowed us to capture the dynamics of MHC ?-helices' steric configurations. Here, we discuss the variability of spline models underlying the geometric analysis with varying polynomial degrees of the splines.

Karch, Rudolf; Schreiner, Wolfgang

2014-01-01

409

The geometric phase in quantum physics  

SciTech Connect

After an explanatory introduction, a quantum system in a classical time-dependent environment is discussed; an example is a magnetic moment in a classical magnetic field. At first, the general abelian case is discussed in the adiabatic approximation. Then the geometric phase for nonadiabatic change of the environment (Anandan--Aharonov phase) is introduced, and after that general cyclic (nonadiabatic) evolution is discussed. The mathematics of fiber bundles is introduced, and some of its results are used to describe the relation between the adiabatic Berry phase and the geometric phase for general cyclic evolution of a pure state. The discussion is restricted to the abelian, U(1) phase.

Bohm, A.

1993-03-01

410

Classical light beams and geometric phases.  

PubMed

We present a study of geometric phases in classical wave and polarization optics using the basic mathematical framework of quantum mechanics. Important physical situations taken from scalar wave optics, pure polarization optics, and the behavior of polarization in the eikonal or ray limit of Maxwell's equations in a transparent medium are considered. The case of a beam of light whose propagation direction and polarization state are both subject to change is dealt with, attention being paid to the validity of Maxwell's equations at all stages. Global topological aspects of the space of all propagation directions are discussed using elementary group theoretical ideas, and the effects on geometric phases are elucidated. PMID:24977351

Mukunda, N; Chaturvedi, S; Simon, R

2014-06-01

411

Mechanics of tunable helices and geometric frustration in biomimetic seashells  

NASA Astrophysics Data System (ADS)

Helical structures are ubiquitous in nature and engineering, ranging from DNA molecules to plant tendrils, from sea snail shells to nanoribbons. While the helical shapes in natural and engineered systems often exhibit nearly uniform radius and pitch, helical shell structures with changing radius and pitch, such as seashells and some plant tendrils, add to the variety of this family of aesthetic beauty. Here we develop a comprehensive theoretical framework for tunable helical morphologies, and report the first biomimetic seashell-like structure resulting from mechanics of geometric frustration. In previous studies, the total potential energy is everywhere minimized when the system achieves equilibrium. In this work, however, the local energy minimization cannot be realized because of the geometric incompatibility, and hence the whole system deforms into a shape with a global energy minimum whereby the energy in each segment may not necessarily be locally optimized. This novel approach can be applied to develop materials and devices of tunable geometries with a range of applications in nano/biotechnology.

Guo, Qiaohang; Chen, Zi; Li, Wei; Dai, Pinqiang; Ren, Kun; Lin, Junjie; Taber, Larry A.; Chen, Wenzhe

2014-03-01

412

Distributed representation of geometrically correlated images with compressed linear measurements.  

PubMed

This paper addresses the problem of distributed coding of images whose correlation is driven by the motion of objects or the camera positioning. It concentrates on the problem where images are encoded with compressed linear measurements. We propose a geometry-based correlation model that describes the common information in pairs of images. We assume that the constitutive components of natural images can be captured by visual features that undergo local transformations (e.g., translation) in different images. We first identify prominent visual features by computing a sparse approximation of a reference image with a dictionary of geometric basis functions. We then pose a regularized optimization problem in order to estimate the corresponding features in correlated images that are given by quantized linear measurements. The correlation model is thus given by the relative geometric transformations between corresponding features. We then propose an efficient joint decoding algorithm that reconstructs the compressed images such that they are consistent with both the quantized measurements and the correlation model. Experimental results show that the proposed algorithm effectively estimates the correlation between images in multiview data sets. In addition, the proposed algorithm provides effective decoding performance that advantageously compares to independent coding solutions and state-of-the-art distributed coding schemes based on disparity learning. PMID:22345540

Thirumalai, Vijayaraghavan; Frossard, Pascal

2012-07-01

413

The effect of furcated hydrogen bond and coordination bond on luminescent behavior of metal-organic framework [CuCN·EIN]: a TDDFT study.  

PubMed

The hydrogen bonding in electronically excited-state of the metal-organic framework [CuCN·EIN] was studied using time-dependent density functional theory (TDDFT). The representative fragment of [CuCN·EIN] was employed for the computation. The geometric structures, binding energies and IR spectra in both ground state and electronically excited state S(1) of the complex were computed using DFT and TDDFT methods to investigate excited-state hydrogen-bonding and coordination bonding, respectively. Based on the analysis of the frontier molecular orbitals and the electronic configuration of the complex, the ligand-to-metal charge transfer (LMCT) luminescence was confirmed. Furthermore, furcated hydrogen bonds are both strengthened in the S(1) state slightly. And then, the strengthening of the hydrogen bonds in the S(1) state goes against the charge transfer from ligand to metal and then should be in favor of the luminescence. In particular, we also discuss strengthening or weakening behavior of the coordination bonds in the S(1) state for the first time. Based on the results of the bond lengths and vibration frequency of the coordination bond, we can conclude that the coordination bond Cu(7)-N(8) is strengthened in the S(1) state. And the strengthening of the coordination bond Cu(7)-N(8) should also be in favor of the luminescence. PMID:22858606

Wu, Danyang; Mi, Weihong; Ji, Min; Hao, Ce; Qiu, Jieshan

2012-11-01

414

The effect of furcated hydrogen bond and coordination bond on luminescent behavior of metal-organic framework [CuCN·EIN]: A TDDFT study  

NASA Astrophysics Data System (ADS)

The hydrogen bonding in electronically excited-state of the metal-organic framework [CuCN·EIN] was studied using time-dependent density functional theory (TDDFT). The representative fragment of [CuCN·EIN] was employed for the computation. The geometric structures, binding energies and IR spectra in both ground state and electronically excited state S1 of the complex were computed using DFT and TDDFT methods to investigate excited-state hydrogen-bonding and coordination bonding, respectively. Based on the analysis of the frontier molecular orbitals and the electronic configuration of the complex, the ligand-to-metal charge transfer (LMCT) luminescence was confirmed. Furthermore, furcated hydrogen bonds are both strengthened in the S1 state slightly. And then, the strengthening of the hydrogen bonds in the S1 state goes against the charge transfer from ligand to metal and then should be in favor of the luminescence. In particular, we also discuss strengthening or weakening behavior of the coordination bonds in the S1 state for the first time. Based on the results of the bond lengths and vibration frequency of the coordination bond, we can conclude that the coordination bond Cu7-N8 is strengthened in the S1 state. And the strengthening of the coordination bond Cu7-N8 should also be in favor of the luminescence.

Wu, Danyang; Mi, Weihong; Ji, Min; Hao, Ce; Qiu, Jieshan

2012-11-01

415

Geometric Templates for Improved Tracking Performance in Monte Carlo Codes  

NASA Astrophysics Data System (ADS)

One of the most fundamental parts of a Monte Carlo code is its geometry kernel. This kernel not only affects particle tracking (i.e., run-time performance), but also shapes how users will input models and collect results for later analyses. A new framework based on geometric templates is proposed that optimizes performance (in terms of tracking speed and memory usage) and simplifies user input for large scale models. While some aspects of this approach currently exist in different Monte Carlo codes, the optimization aspect has not been investigated or applied. If Monte Carlo codes are to be realistically used for full core analysis and design, this type of optimization will be necessary. This paper describes the new approach and the implementation of two template types in MC21: a repeated ellipse template and a box template. Several different models are tested to highlight the performance gains that can be achieved using these templates. Though the exact gains are naturally problem dependent, results show that runtime and memory usage can be significantly reduced when using templates, even as problems reach realistic model sizes.

Nease, Brian R.; Millman, David L.; Griesheimer, David P.; Gill, Daniel F.

2014-06-01

416

Hydrogen bond and halogen bond inside the carbon nanotube  

NASA Astrophysics Data System (ADS)

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.

Wang, Weizhou; Wang, Donglai; Zhang, Yu; Ji, Baoming; Tian, Anmin

2011-02-01

417

Parental Bonding Instrument  

Microsoft Academic Search

The view that those with obsessive compulsive disorder or obsessional personality have been exposed to overcontrolling and overcritical parenting is examined. Two measures of obsessionality (the Maudsley Obsessional-Compulsive Inventory and the Leyton Obsessionality Inventory) were completed by 344 nonclinical subjects. They also scored their parents on the Parental Bonding Instrument (PBI), a measure assessing perceived levels of parental care and

L. C. Cavedo; G. Parker

1994-01-01

418

Bonding with Your Baby  

MedlinePLUS

... your area. Breastfeeding and bottle-feeding are both natural times for bonding. Infants respond to the smell and touch of their mothers, as well as the responsiveness of the parents to their needs. In an uncomplicated birth, caregivers try to take advantage of the infant's ...

419

Photochemical tissue bonding  

DOEpatents

Photochemical tissue bonding methods include the application of a photosensitizer to a tissue and/or tissue graft, followed by irradiation with electromagnetic energy to produce a tissue seal. The methods are useful for tissue adhesion, such as in wound closure, tissue grafting, skin grafting, musculoskeletal tissue repair, ligament or tendon repair and corneal repair.

Redmond, Robert W. (Brookline, MA); Kochevar, Irene E. (Charlestown, MA)

2012-01-10

420

Bonding in cementitious composites  

Microsoft Academic Search

These proceedings discuss the papers presented at the symposium on the subject of high performance cement composites. Some of the topics discussed were; calcium hydroxides treated ceramics microspheres and mechanical properties of high temperature light weight cements; microstructure and chemical variations of class F fly ash; microstructure and bond strength of cement and crack propagation as detected by laser holography

Mindess

1988-01-01

421

Geometric algorithm for efficient coincident detection of gravitational waves  

SciTech Connect

Data from a network of gravitational-wave detectors can be analyzed in coincidence to increase detection confidence and reduce nonstationarity of the background. We propose and explore a geometric algorithm to combine the data from a network of detectors. The algorithm makes optimal use of the variances and covariances that exist among the different parameters of a signal in a coincident detection of events. The new algorithm essentially associates with each trigger ellipsoidal regions in parameter space defined by the covariance matrix. Triggers from different detectors are deemed to be in coincidence if their ellipsoids have a nonzero overlap. Compared to an algorithm that uses uncorrelated windows separately for each of the signal parameters, the new algorithm greatly reduces the background rate thereby increasing detection efficiency at a given false alarm rate.

Robinson, C. A. K.; Sathyaprakash, B. S. [School of Physics and Astronomy, Cardiff University, 5, The Parade, Cardiff, United Kingdom, CF24 3AA (United Kingdom); Sengupta, Anand S. [School of Physics and Astronomy, Cardiff University, 5, The Parade, Cardiff, United Kingdom, CF24 3AA (United Kingdom); LIGO Laboratory, California Institute of Technology, Pasadena, California 91125 (United States)

2008-09-15

422

Correlation applied to the recognition of regular geometric figures  

NASA Astrophysics Data System (ADS)

It developed a system capable of recognizing of regular geometric figures, the images are taken by the software automatically through a process of validating the presence of figure to the camera lens, the digitized image is compared with a database that contains previously images captured, to subsequently be recognized and finally identified using sonorous words referring to the name of the figure identified. The contribution of system set out is the fact that the acquisition of data is done in real time and using a spy smart glasses with usb interface offering an system equally optimal but much more economical. This tool may be useful as a possible application for visually impaired people can get information of surrounding environment.

Lasso, William; Morales, Yaileth; Vega, Fabio; Díaz, Leonardo; Flórez, Daniel; Torres, Cesar

2013-11-01

423

Measurement of supramolecular effective molarities for intramolecular H-bonds in zinc porphyrin-imidazole complexes.  

PubMed

The association constants for formation of 1?:?1 complexes between five different imidazole ligands and eight different porphyrins have been measured by UV/vis titration experiments in two different solvents, toluene and 1,1,2,2-tetrachloroethane (TCE). Ligands equipped with H-bond acceptors (ester or amide) and porphyrins equipped with H-bond donors (phenol) can make H-bonds in addition to the zinc-nitrogen coordination interaction. The free energy contributions of these H-bonds to the overall stabilities of the complexes were determined using chemical double mutant cycles. Amide-phenol H-bonds contribute up to 5 kJ mol(-1) to the free energy change on complexation, and ester-phenol H-bonds contribute up to 3 kJ mol(-1). Porphyrin-ligand combinations with poor geometric complementarity do not make detectable H-bonding interactions. Effective molarities (EM) for the formation of H-bonds in the complexes were estimated by comparing the equilibrium constants for formation of the intramolecular interaction with the corresponding intermolecular interaction: the values are between 3 mM and 200 mM, which is comparable to previous results obtained for porphyrin-pyridine complexes. The values of EM measured for flexible and rigid ligand systems are comparable. This suggests that there is a trade off between restriction of conformational mobility in the flexible ligands and geometric strain in the rigid ligands, which results in similar binding affinities. PMID:24442274

Jinks, Michael A; Sun, Hongmei; Hunter, Christopher A

2014-03-01

424

Hyperconjugation-mediated solvent effects in phosphoanhydride bonds.  

PubMed

Density functional theory and natural bond orbital analysis are used to explore the impact of solvent on hyperconjugation in methyl triphosphate, a model for "energy rich" phosphoanhydride bonds, such as found in ATP. As expected, dihedral rotation of a hydroxyl group vicinal to the phosphoanhydride bond reveals that the conformational dependence of the anomeric effect involves modulation of the orbital overlap between the donor and acceptor orbitals. However, a conformational independence was observed in the rotation of a solvent hydrogen bond. As one lone pair orbital rotates away from an optimal antiperiplanar orientation, the overall magnitude of the anomeric effect is compensated approximately by the other lone pair as it becomes more antiperiplanar. Furthermore, solvent modulation of the anomeric effect is not restricted to the antiperiplanar lone pair; hydrogen bonds involving gauche lone pairs also affect the anomeric interaction and the strength of the phosphoanhydride bond. Both gauche and anti solvent hydrogen bonds lengthen nonbridging O-P bonds, increasing the distance between donor and acceptor orbitals and decreasing orbital overlap, which leads to a reduction of the anomeric effect. Solvent effects are additive with greater reduction in the anomeric effect upon increasing water coordination. By controlling the coordination environment of substrates in an active site, kinases, phosphatases, and other enzymes important in metabolism and signaling may have the potential to modulate the stability of individual phosphoanhydride bonds through stereoelectronic effects. PMID:23009395

Summerton, Jean C; Evanseck, Jeffrey D; Chapman, Michael S

2012-10-18

425

Entanglement capacity of nonlocal Hamiltonians: A geometric approach  

NASA Astrophysics Data System (ADS)

We develop a geometric approach to quantify the capability of creating entanglement for a general physical interaction acting on two qubits. We use the entanglement measure proposed by us for N -qubit pure states [Ali Saif M. Hassan and Pramod S. Joag, Phys. Rev. A 77, 062334 (2008)]. This geometric method has the distinct advantage that it gives the experimentally implementable criteria to ensure the optimal entanglement production rate without requiring a detailed knowledge of the state of the two qubit system. For the production of entanglement in practice, we need criteria for optimal entanglement production, which can be checked in situ without any need to know the state, as experimentally finding out the state of a quantum system is generally a formidable task. Further, we use our method to quantify the entanglement capacity in higher level and multipartite systems. We quantify the entanglement capacity for two qutrits and find the maximal entanglement generation rate and the corresponding state for the general isotropic interaction between qutrits, using the entanglement measure of N -qudit pure states proposed by us [Ali Saif M. Hassan and Pramod S. Joag, Phys. Rev. A 80, 042302 (2009)]. Next we quantify the genuine three qubit entanglement capacity for a general interaction between qubits. We obtain the maximum entanglement generation rate and the corresponding three qubit state for a general isotropic interaction between qubits. The state maximizing the entanglement generation rate is of the Greenberger-Horne-Zeilinger class. To the best of our knowledge, the entanglement capacities for two qutrit and three qubit systems have not been reported earlier.

Lari, Behzad; Hassan, Ali Saif M.; Joag, Pramod S.

2009-12-01

426

On the geometrical form of volcanoes  

Microsoft Academic Search

Many volcanic edifices have a remarkably symmetric geometrical form. An example is Mount Fuji in Japan. We model this form assuming that the surface of the volcano is a surface of uniform hydraulic potential; that an erupting magma will follow the path of minimum resistance to the surface. In order to model the resistance to fluid flow we assume the

A. Lacey; J. R. Ockendon; D. L. Turcotte

1981-01-01

427

Minkowski Geometric Algebra of Complex Sets  

Microsoft Academic Search

A geometric algebra of point sets in the complex plane is proposed, based on two fundamental operations: Minkowski sums and products. Although the (vector) Minkowski sum is widely known, the Minkowski product of two-dimensional sets (induced by the multiplication rule for complex numbers) has not previously attracted much attention. Many interestingapplications, interpretations, and connections arisefromthegeometric algebrabased ontheseoperations. Minkowskiproductswith lines and

RIDA T. FAROUKI; HWAN PYO MOON; BAHRAM RAVANI

2000-01-01

428

Segmenting Geometric Reliefs from Textured Background Surfaces  

Microsoft Academic Search

Segmentation of geometric reliefs from a textured background has various applications in reverse engineering. We consider two approaches to solve this problem. The first classifies parts of a surface mesh as relief or background, and then uses a snake which moves inwards towards the desired relief boundary, which is coarsely located using an energy based on the classification. The second

Shenglan Liu; Ralph R. Martin; Frank C. Langbein; Paul L. Rosin

2007-01-01

429

Geometric and Harmonic Means and Progressions  

Microsoft Academic Search

.  Geometer Marcus the Marinite explores how the geometric and harmonic means can be employed compositionally within a frame;\\u000a how means function in the development of organizational field grids; how means work to develop linear perspective and proportional\\u000a grids.

Mark A. Reynolds

2001-01-01

430

The geometric models of Europe's core area  

Microsoft Academic Search

This study focuses on the spatial structure of the European Union. The aim of the research is to analyse the geometric models of Europe's core area. We have a lot of flat shapes fo r the spatial structure: we have axes, polygons (triangles, squar es, a pentagon) and they have a lot of different geographical exten sions in Europe. These

PÁL SZABÓ

431

Rupture dynamics of a geometrically complex fault  

NASA Astrophysics Data System (ADS)

We study the propagation of a two dimensional antiplane rupture along a complex geometrical fault containing a series of kinks of different angles and intervals between the kinks. Numerical solutions are obtained using the spectral element methods developed by Vilotte, Ampuero and Komatisch. We model both periodically kinked and simple versions of randomly kinked faults. We compare our simulations with the results obtained for rupture propagation along flat faults. We find that geometrically complex differ substantially from flat faults. First, complex faults emit high frequency radiation of ?-2 type every time they encounter geometrical discontinuities, this produces a strong damping of rupture propagation. Second, the average rupture speed along the overall direction of the fault is substantially reduced and, depending on the nature of the geometrical discontinuities, ruptures may be easily stopped. Energy release rates computed assuming that the fault is flat increase as the fault becomes increasingly complex. The stress field around the fault may be described as a corridor of strongly variable stress with patches of stress increase and decrease even if the slip on the fault is continuous. Contrary to flat faults, earthquake propagation leaves behind a complex final state of stress. Our model confirms the experimental findings of many authors who worked on high speed mode I fracture.

Madariaga, R. I.; Ampuero, J.

2005-12-01

432

Geometric Invariant Domain for Image Watermarking  

Microsoft Academic Search

To enable copyright protection and authentication, robust digital wa- termark can be embedded into multimedia contents imperceptibly. However, geometric distortions pose a significant threat to robust image watermarking because it can desynchronize the watermark information while preserving the visual quality. To overcome this, we developed an i nvariant domain with three transforms; Fast Fourier Transform (FFT), Log-Polar Mapping (LPM), and

Chaw-seng Woo; Jiang Du; Binh Pham

2006-01-01

433

Geometrical metallic shell behavior study under compression  

NASA Astrophysics Data System (ADS)

The loading response of shell structures depends on their shapes. The individual shape behaves uniquely to the loading, and different shapes give different load displacement graphs. If these geometries are combined, then their load displacement graphs can be different. It may happen that their combined behavior can be harnessed to be used as better energy absorber in a controlled manner, which they cannot if they are used individually. Experiments were conducted on two separate geometries as well by joining them with weld. The first geometry was the top cylindrical and frusta bottom. The second geometry was the shape of inverted bell crater and half-spherical shells. Combining these two shapes produced the third geometrical shape. The large deformation was obtained by crushing these geometrical shells between two flat plates. The finite element analysis was used to simulate the crush phenomenon. The behavior of the geometrical shell to large deformation was understood with load displacement graph for different samples. The energy absorbed by the different samples was calculated and compared. The parameters, like material and thickness, were varied for the samples to see their effect on the large deformation behavior. Moreover, friction role is discussed on the crush phenomenon. This paper also gives an idea on the different parameters which can affect the energy-absorbing capacity of the combined geometrical shells.

Sahu, Ram Ranjan; Gupta, Pramod Kumar

2013-12-01

434

Understanding Suomi NPP VIIRS geometric performance  

NASA Astrophysics Data System (ADS)

The NASA/NOAA Visible Infrared Imager Radiometer Suite (VIIRS) is a key instrument on-board the Suomi National Polar-orbiting Partnership (SNPP) satellite. VIIRS will be used by the science research community to continue long-term measurements of geophysical variables and the by operational community for weather forecasting and disaster relief and other applications. Since the first VIIRS data became available in December 2011, our team has been assessing VIIRS' geometric performance using earth and lunar data. We have measured the sensor's on-orbit spatial response, band-to-band co-registration, and geolocation accuracy and precision. Our geometric performance assessment is an important aspect of the VIIRS sensor data record calibration and validation process. We will discuss VIIRS' geometric performance based on this first year of VIIRS on-orbit data. These results will be compared to the at-launch performance and modeling. Overall, VIIRS' on-orbit geometric performance is very good and matches the pre-launch performance expectations, and so is likely to meet the needs of both the long-term monitoring and operational communities.

Wolfe, R. E.; Lin, G.; Nishihama, M.

2012-12-01

435

Geometric Models for Collaborative Search and Filtering  

ERIC Educational Resources Information Center

This dissertation explores the use of geometric and graphical models for a variety of information search and filtering applications. These models serve to provide an intuitive understanding of the problem domains and as well as computational efficiencies to our solution approaches. We begin by considering a search and rescue scenario where both…

Bitton, Ephrat

2011-01-01

436

Geometric Representations for Discrete Fourier Transforms  

NASA Technical Reports Server (NTRS)

Simple geometric representations show symmetry and periodicity of discrete Fourier transforms (DFT's). Help in visualizing requirements for storing and manipulating transform value in computations. Representations useful in any number of dimensions, but particularly in one-, two-, and three-dimensional cases often encountered in practice.

Cambell, C. W.

1986-01-01

437

Global Geometric Properties of Martian Impact Craters  

NASA Technical Reports Server (NTRS)

We present impact crater geometric properties for more than 5000 fresh martian features using high resolution Mars Orbiter Laser Altimeter digital elevation models and topographic profiles. We discuss global results and significant regional variations. Additional information is contained in the original extended abstract.

Garvin, J. B.; Sakimoto, S. E. H.; Frawley, J. J.; Schnetzler, C.

2002-01-01

438

Rejuvenating Allen's Arc with the Geometric Mean.  

ERIC Educational Resources Information Center

Contends that, despite ongoing criticism, Allen's arc elasticity formula remains entrenched in the microeconomics principles curriculum. Reviews the evolution and continuing scrutiny of the formula. Argues that the use of the geometric mean offers pedagogical advantages over the traditional arithmetic mean approach. (CFR)

Phillips, William A.

1994-01-01

439

Visualizing Geometrical Statements with GeoView  

Microsoft Academic Search

We describe a tool that combines a general purpose theorem prover and an o-the- shelf interface for dynamic geometry drawing to enhance man-machine interaction involving geometrical proofs. With our tool, we can edit the statements of geo- metrical theorems, construct and verify their proofs with the theorem prover, and visualize the statements using the drawing tool. The key component is

Yves Bertot; Frédérique Guilhot; Loic Pottier

2004-01-01

440

Reflections on representing non-geometric data  

NASA Technical Reports Server (NTRS)

The American National Standard Y14.26M-1981 on Digital Representation for Communication of Product Definition Data includes an introduction, three sections corresponding to IGES (Initial Graphics Exchange Specification) Version 1.0, and Section 5, which is a constructive, relational, language based representation for geometric and topological entitles.

Emnett, R. F.; Shu, H. H.

1984-01-01

441

A graph spectrum based geometric biclustering algorithm.  

PubMed

Biclustering is capable of performing simultaneous clustering on two dimensions of a data matrix and has many applications in pattern classification. For example, in microarray experiments, a subset of genes is co-expressed in a subset of conditions, and biclustering algorithms can be used to detect the coherent patterns in the data for further analysis of function. In this paper, we present a graph spectrum based geometric biclustering (GSGBC) algorithm. In the geometrical view, biclusters can be seen as different linear geometrical patterns in high dimensional spaces. Based on this, the modified Hough transform is used to find the Hough vector (HV) corresponding to sub-bicluster patterns in 2D spaces. A graph can be built regarding each HV as a node. The graph spectrum is utilized to identify the eigengroups in which the sub-biclusters are grouped naturally to produce larger biclusters. Through a comparative study, we find that the GSGBC achieves as good a result as GBC and outperforms other kinds of biclustering algorithms. Also, compared with the original geometrical biclustering algorithm, it reduces the computing time complexity significantly. We also show that biologically meaningful biclusters can be identified by our method from real microarray gene expression data. PMID:23079285

Wang, Doris Z; Yan, Hong

2013-01-21

442

Physical Geometric Algorithms for Structural Molecular Biology  

Microsoft Academic Search

A wealth of interesting computational problems arises in proposed methods for discovering new pharmaceuti- cals. This paper surveys our recent work in three key areas, using a Physical Geometric Algorithm (PGA) ap- proach to data interpretation, experiment planning, and drug design: (1) Data-directed computational protocols for high- throughput protein structure determination. A key com- ponent of structure determination through nuclear

Chris Bailey-Kellogg; Jack Kelley; Ryan H. Lilien

2001-01-01

443

Geometric Mean--What Does It Mean?  

ERIC Educational Resources Information Center

The National Council of Teachers of Mathematics and numerous mathematics educators promote the combination of conceptual understanding and procedural learning in the successful instruction of mathematics. Despite this, when geometric mean is taught in a typical American geometry class, it is taught as a process only despite the many connections…

Kalder, Robin S.

2012-01-01

444

A Geometric Approach to Fair Division  

ERIC Educational Resources Information Center

We wish to divide a cake among some collection of people (who may have very different notions of the comparative value of pieces of cake) in a way that is both "fair" and "efficient." We explore the meaning of these terms, introduce two geometric tools to aid our analysis, and present a proof (due to Dietrich Weller) that establishes the existence…

Barbanel, Julius

2010-01-01

445

Geometric Interpretations of Some Psychophysical Results.  

ERIC Educational Resources Information Center

A theory of psychophysics is discussed that enlarges the classical theory in three general ways: (1) the multidimensional nature of perception is made explicit; (2) the transformations of the theory are interpreted geometrically; and (3) attributes are distinguished from sensations and only partially ordered. It is shown that, with the enlarged…

Levine, Michael V.

446

Robust adaptive floating-point geometric predicates  

Microsoft Academic Search

Fast C implementations of four geometric predicates, the 2D and 3D orientation and incircle tests, are publicly avail- able. Their inputs are ordinary single or double precision floating-point numbers. They owe their speed to two fea- tures. First, they employ new fast algorithms for arbitrary precision arithmetic that have a strong advantage over other software techniques in computations that manipulate

Johnathan Richard Shewchuk

1996-01-01

447

More Meaning from the Geometric Mean.  

ERIC Educational Resources Information Center

Provides classroom suggestions for combining numerical, algebraic, and geometric techniques with the understanding of a simple method for computing square roots. Historical origins of the method illustrate the debt owed to ancient minds living in what are now India, Pakistan, Iraq, and Egypt. (Author/NB)

Dorner, Bryan C.

2003-01-01

448

The geometric thickness of low degree graphs  

Microsoft Academic Search

We prove that the geometric thickness of graphs whose maximum degree is no more than four is two. All of our algorithms run in O(n) time, where n is the number of vertices in the graph. In our proofs, we present an embedding algorithm for graphs with maximum degree three that uses an n x n grid and a more

Christian A. Duncan; David Eppstein; Stephen G. Kobourov

2004-01-01

449

Geometric Transformations in Middle School Mathematics Textbooks  

ERIC Educational Resources Information Center

This study analyzed treatment of geometric transformations in presently available middle grades (6, 7, 8) student mathematics textbooks. Fourteen textbooks from four widely used textbook series were evaluated: two mainline publisher series, Pearson (Prentice Hall) and Glencoe (Math Connects); one National Science Foundation (NSF) funded curriculum…

Zorin, Barbara

2011-01-01

450

Using geometric algebra to study optical aberrations  

SciTech Connect

This paper uses Geometric Algebra (GA) to study vector aberrations in optical systems with square and round pupils. GA is a new way to produce the classical optical aberration spot diagrams on the Gaussian image plane and surfaces near the Gaussian image plane. Spot diagrams of the third, fifth and seventh order aberrations for square and round pupils are developed to illustrate the theory.

Hanlon, J.; Ziock, H.

1997-05-01

451

Geometric couplings and brane supersymmetry breaking  

NASA Astrophysics Data System (ADS)

Orientifold vacua allow the simultaneous presence of supersymmetric bulks, with one or more gravitinos, and nonsupersymmetric combinations of BPS branes. This "brane supersymmetry breaking" raises the issue of consistency for the resulting gravitino couplings, and Dudas and Mourad recently provided convincing arguments to this effect for the ten-dimensional USp(32) model. These rely on a nonlinear realization of local supersymmetry à la Volkov-Akulov, although no gravitino mass term is present, and the couplings have a nice geometrical interpretation in terms of "dressed" bulk fields, aside from a Wess-Zumino-like term, resulting from the supersymmetrization of the Chern-Simons couplings. Here we show that all couplings can be given a geometrical interpretation, albeit in the dual 6-form model, whose bulk includes a Wess-Zumino term, so that the nongeometric ones are in fact demanded by the geometrization of their duals. We also determine the low-energy couplings for six-dimensional (1,0) models with brane supersymmetry breaking. Since these include both Chern-Simons and Wess-Zumino terms, only the resulting field equations are geometrical, aside from contributions due to vectors of supersymmetric sectors.

Pradisi, Gianfranco; Riccioni, Fabio

2001-11-01

452

Geometrical Tile Design for Complex Neighborhoods  

PubMed Central

Recent research has showed that tile systems are one of the most suitable theoretical frameworks for the spatial study and modeling of self-assembly processes, such as the formation of DNA and protein oligomeric structures. A Wang tile is a unit square, with glues on its edges, attaching to other tiles and forming larger and larger structures. Although quite intuitive, the idea of glues placed on the edges of a tile is not always natural for simulating the interactions occurring in some real systems. For example, when considering protein self-assembly, the shape of a protein is the main determinant of its functions and its interactions with other proteins. Our goal is to use geometric tiles, i.e., square tiles with geometrical protrusions on their edges, for simulating tiled paths (zippers) with complex neighborhoods, by ribbons of geometric tiles with simple, local neighborhoods. This paper is a step toward solving the general case of an arbitrary neighborhood, by proposing geometric tile designs that solve the case of a “tall” von Neumann neighborhood, the case of the f-shaped neighborhood, and the case of a 3?×?5 “filled” rectangular neighborhood. The techniques can be combined and generalized to solve the problem in the case of any neighborhood, centered at the tile of reference, and included in a 3 × (2k?+?1) rectangle.

Czeizler, Eugen; Kari, Lila

2009-01-01

453

Travel Time Inversion: A Geometrical Approach  

Microsoft Academic Search

A geometric formulation of the seismic travel time problem is given based upon the use of slowness as an independent variable. Many of the difficulties in the conventional treatment (e.g., singular kernels) are therebyavoided. Furthermore, it is shown that the inverse problem possesses an inherently linear formulation. In this formalism we are able to provide extremal solutions giving upper and

Jan Garmany; John A. Orcutt; Robert L. Parker

1979-01-01

454

Geometric voting algorithm for star trackers  

Microsoft Academic Search

We present an algorithm for recovering the orientation (attitude) of a satellite-based camera. The algorithm matches stars in an image taken with the camera to stars in a star catalogue. The algorithm is based on a geometric voting scheme in which a pair of stars in the catalogue votes for a pair of stars in the image if the angular

Michael Kolomenkin; Sharon Pollak; Ilan Shimshoni; Michael Lindenbaum

2008-01-01

455

Geometric Series and Computers--An Application.  

ERIC Educational Resources Information Center

This article considers the sum of a finite geometric series as applied to numeric data storage in the memory of an electronic digital computer. The presentation is viewed as relevant to programing in several languages and removes some of the mystique associated with syntax constraints that any language imposes. (MP)

McNerney, Charles R.

1983-01-01

456

Geometric Partial Differential Equations and Image Analysis  

Microsoft Academic Search

This book provides an introduction to the use of geometric partial differential equations in image processing and computer vision. It brings a number of new concepts into the field, providing a very fundamental and formal approach to image processing. State-of-the-art practical results in a large number of real problems are achieved with the techniques described. Applications covered include image segmentation,

Guillermo Sapiro

2001-01-01

457

A New Approach to Geometric Fitting  

Microsoft Academic Search

Geometric fitting — parameter estimation for data subject to im- plicit parametric constraints — is a very common sub-problem in computer vision, used for curve, surface and 3D model fitting , matching constraint estimation and 3D reconstruction under con- straints. Although many algorithms exist for specific cases , the general problem is by no means 'solved' and has recently beco

Bill Triggs

1997-01-01

458

On Culture, Geometrical Thinking and Mathematics Education.  

ERIC Educational Resources Information Center

Confronts a widespread prejudice about mathematical knowledge, that mathematics is "culture-free," by demonstrating alternative constructions of Euclidean geometrical ideas developed from the culture of Mozambique. As well as establishing the educational power of these constructions, the article illustrates the methodology of "culture…

Gerdes, Paulus

1988-01-01

459

Geometric video approximation using weighted matching pursuit.  

PubMed

In recent years, works on geometric multidimensional signal representations have established a close relation with signal expansions on redundant dictionaries. For this purpose, matching pursuits (MP) have shown to be an interesting tool. Recently, most important limitations of MP have been underlined, and alternative algorithms like weighted-MP have been proposed. This work explores the use of weighted-MP as a new framework for motion-adaptive geometric video approximations. We study a novel algorithm to decompose video sequences in terms of few, salient video components that jointly represent the geometric and motion content of a scene. Experimental coding results on highly geometric content reflect how the proposed paradigm exploits spatio-temporal video geometry. Two-dimensional weighted-MP improves the representation compared to those based on 2-D MP. Furthermore, the extracted video components represent relevant visual structures with high saliency. In an example application, such components are effectively used as video descriptors for the joint audio-video analysis of multimedia sequences. PMID:19389695

Divorra Escoda, Oscar; Monaci, Gianluca; Figueras I Ventura, Rosa M; Vandergheynst, Pierre; Bierlaire, Michel

2009-08-01

460

A geometric approach to spectral subtraction  

Microsoft Academic Search

The traditional power spectral subtraction algorithm is computationally simple to implement but suffers from musical noise distor- tion. In addition, the subtractive rules are based on incorrect assumptions about the cross terms being zero. A new geometric approach to spectral subtraction is proposed in the present paper that addresses these shortcomings of the spectral subtraction algorithm. A method for estimating

Yang Lu; Philipos C. Loizou

2008-01-01

461

Robot arm geometric link parameter estimation  

Microsoft Academic Search

A general method for estimating serial link manipulator geometric parameter errors is proposed in this paper. The positioning accuracy of the end-effector may be increased significantly by updating the nominal link parameters in the control software to represent the physical system more accurately. The proposed method is applicable for serial link manipulators with any combination of revolute or prismatic joints,

Samad A. Hayati

1983-01-01

462

A geometric framework for unsupervised anomaly detection  

Microsoft Academic Search

Abstract: Most current intrusion detection systems employ signature-based methods or datamining-based methods which rely on labeled training data. This training data is typicallyexpensive to produce. We present a new geometric framework for unsupervisedanomaly detection, which are algorithms that are designed to process unlabeled data.

Eleazar Eskin; Andrew Arnold; Michael Prerau; Leonid Portnoy; Sal Stolfo

2002-01-01

463

The differential geometric modelling of compressor blades  

Microsoft Academic Search

Surface splining is used to obtain a differential geometric model for complicated smooth surfaces, e.g., refurbished compressor blades. Modifications to standard parametric splining techniques are introduced to improve the accuracy of the modelling scheme, to maintain stability, and to clear the way for real-time automation. The differential geometry underlying the model can be used to assist in deburring, surface finishing

R. M. H. Cheng; R. Rajagopalan; M. Temple-Raston

1994-01-01

464

Bond strength comparison of color change adhesives for orthodontic bonding.  

PubMed

This study investigated whether three different color change light-cured orthodontic bonding adhesives have comparable shear bond strengths to a conventional light-cured orthodontic bonding adhesive. The sample of 240 bovine incisors was divided into four groups of 60 each. Each group tested one of four orthodontic bonding adhesives: 3M Unitek Transbond PLUS, Ormco Gréngloo, Ormco Blúgloo, and 3M Unitek Transbond XT (control). The four groups were further divided into two subgroups of 30 with shear bond strength tested at two different times (15 minutes and 24 hours) post-bond. The shear bond strength was measured on a universal testing machine. The data were analyzed by two-way analysis of variance and post-hoc comparisons (Fisher's PLSD) at the 0.05 level of significance. The average shear bond strength was greater at 24 hours than at 15 minutes for Transbond PLUS, Blúgloo, and Transbond XT. For Gréngloo, the average shear bond strength was greater at 15 minutes than at 24 hours. Gréngloo tested at 15 minutes had the highest average shear bond strength. Gréngloo tested at 24 hours had the lowest average shear bond strength. All four orthodontic bonding adhesives demonstrated bond strengths considered to be clinically acceptable for orthodontic purposes. PMID:21667823

Duers, Michael W; English, Jeryl D; Ontiveros, Joe C; Powers, John M; Bussa, Harry I; Frey, Gary N; Gallerano, Ronald L; Paige, Sebastian Z

2011-03-01

465

A GEOMETRICAL HEIGHT SCALE FOR SUNSPOT PENUMBRAE  

SciTech Connect

Inversions of spectropolarimetric observations of penumbral filaments deliver the stratification of different physical quantities in an optical depth scale. However, without establishing a geometrical height scale, their three-dimensional geometrical structure cannot be derived. This is crucial in understanding the correct spatial variation of physical properties in the penumbral atmosphere and to provide insights into the mechanism capable of explaining the observed penumbral brightness. The aim of this work is to determine a global geometrical height scale in the penumbra by minimizing the divergence of the magnetic field vector and the deviations from static equilibrium as imposed by a force balance equation that includes pressure gradients, gravity, and the Lorentz force. Optical depth models are derived from the inversion of spectropolarimetric data of an active region observed with the Solar Optical Telescope on board the Hinode satellite. We use a genetic algorithm to determine the boundary condition for the inference of geometrical heights. The retrieved geometrical height scale permits the evaluation of the Wilson depression at each pixel and the correlation of physical quantities at each height. Our results fit into the uncombed penumbral scenario, i.e., a penumbra composed of flux tubes with channeled mass flow and with a weaker and more horizontal magnetic field as compared with the background field. The ascending material is hotter and denser than their surroundings. We do not find evidence of overturning convection or field-free regions in the inner penumbral area analyzed. The penumbral brightness can be explained by the energy transfer of the ascending mass carried by the Evershed flow, if the physical quantities below z = -75 km are extrapolated from the results of the inversion.

Puschmann, K. G.; Ruiz Cobo, B.; MartInez Pillet, V., E-mail: kgp@iac.e, E-mail: brc@iac.e, E-mail: vmp@iac.e [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain)

2010-09-10

466

Can EPR non-locality be geometrical?  

SciTech Connect

The presence in Quantum Mechanics of non-local correlations is one of the two fundamentally non-intuitive features of that theory. The non-local correlations themselves fall into two classes: EPR and Geometrical. The non-local characteristics of the geometrical type are well-understood and are not suspected of possibly generating acausal features, such as faster-than-light propagation of information. This has especially become true since the emergence of a geometrical treatment for the relevant gauge theories, i.e. Fiber Bundle geometry, in which the quantum non-localities are seen to correspond to pure homotopy considerations. This aspect is reviewed in section 2. Contrary-wise, from its very conception, the EPR s