Sample records for optimized geometric bond

  1. Water filtration optimization by geometric programming 

    E-print Network

    Wray, Duane Jimmy

    1970-01-01

    MATER FILTRATION OPTIMIZATION BY GEOMETRIC PROGRAMMING A Thesis by DUANE JIMMY WRAY Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1970 Major... Subject: Industrial Engineering WATER FILTRATION OPTIMIZATION BY GEOMETRIC PROGRAMMING A Thesis by DUANE JIMMY WRAY Chairman of Committee) (Head of Department) (Member) M p, ~ (Member)' December 1970 ABSTRACT Water Fi 1 trati on Optimization...

  2. Average case analysis of dynamic geometric optimization

    E-print Network

    Eppstein, David

    for constructing geometric structures such as convex hulls and ar- rangements. Such algorithms can also be used structures: convex hulls, arrangements, and the like. However problems of geometric optimization have been ne spanning tree of a planar point set, as points are inserted or deleted, in O(log3 n) expected time per

  3. Evolutionary Optimization of a Geometrically Refined Truss

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  4. Optimization of Inductor Circuits via Geometric Programming

    E-print Network

    constrains the available design space, the latter one requires a so- phisticated search engine, a large S. Mohan, Stephen P. Boyd, Thomas H. Lee Electrical Engineering Department, Stanford University the design problem as a special type of optimization problem called geometric pro- gramming, for which

  5. Geometric Optimization of Spin Current

    NASA Astrophysics Data System (ADS)

    Melander, Josh; Urazhdin, Sergei

    2012-10-01

    Spintronics is the study of spin transport electronics. Already employed in data storage technologies, spintronics offers the opportunity to continue to shrink electronic devices past what traditional electronics are capable of. The application of spintronics requires highly optimized devices; more so than what is available currently. In this experiment we aim to optimize spin transport properties through the geometry of the device. More specifically, we investigate how the thickness of the sample affects the diffusion length of the spin current (SC). The sample device is a multilayer made up of FeMn(0.5)Pt(x)Py(5), where x is the thickness in nm, sputtered onto an oxidized silicon chip. SC is then induced by the Spin Hall Effect (SHE) which occurs when a current is passed through the Pt layer. The effect of SC on Py is measured by Brillouin light scattering (BLS) spectroscopy. Our data shows that spin diffusion length is dependent on the thickness of the sample and we are currently working to formulate a working model for it.

  6. Optimizing ultrasonic imaging for adhesively bonded plates

    SciTech Connect

    Conboy, Mike; Hart, Scot; Harris-Weiel, David; Meyer, R. L. (Rachel L.); Claytor, T. N. (Thomas N.)

    2004-01-01

    Bonded materials are used in many critical applications, making it important to determine the state of the adhesive during service or aging. It is also of importance, in many cases, to determine if the adhesive has uniformly and completely covered the area to be joined. Through dual transducer scanning, focused and unfocused transducers, and immersion scanning, the uniformity and adherence of a visco-elastic material can be evaluated. In this report, ultrasonic scanning parameters will be optimized experimentally with guidance from simulation tools including Wave 2000 pro and Imagine 3D. We explored optimizing the contrast ratio by varying the interrogation frequency and also by adjusting the distance between the transducer and bond line. An improvement in contrast should also increase the ability to detect differences in compositions and viscosity of the bonded layer. By maximizing the contrast the quality of the visco-elastic bond can be determined, and imperfections detected before adhesive failure.

  7. Adatom bond-induced geometric and electronic properties of passivated armchair graphene nanoribbons.

    PubMed

    Lin, Yu-Tsung; Chung, Hsien-Ching; Yang, Po-Hua; Lin, Shih-Yang; Lin, Ming-Fa

    2015-07-01

    The geometric and electronic properties of passivated armchair graphene nanoribbons, enriched by strong chemical bonding between edge-carbons and various adatoms, are investigated by first-principle calculations. Adatom arrangements, bond lengths, charge distributions, and energy dispersions are dramatically changed by edge passivation. Elements with an atomic number of less than 20 are classified into three types depending on the optimal geometric structures: planar and non-planar structures, the latter of which are associated with specific arrangements and stacked configurations of adatoms. Especially, the nitrogen passivated nanoribbon is the most stable one with a heptagon-pentagon structure at the edges. The low-lying band structures are drastically varied, exhibiting non-monotonous energy dispersions and adatom-dominated bands. A relationship between energy gaps and ribbon widths no longer exists, and some adatoms further induce a semiconductor-metal transition. All the main characteristics are directly reflected in the density of states, revealing dip structures, plateaus, symmetric peaks, and square-root divergent asymmetric peaks. PMID:26051862

  8. Introduction to geometric processing through optimization.

    PubMed

    Taubin, Gabriel

    2012-01-01

    As an introduction to the field, this article shows how to formulate several geometry-processing operations to solve systems of equations in the "least-squares" sense. The equations are derived from local geometric relations using elementary concepts from analytic geometry, such as points, lines, planes, vectors, and polygons. Simple and useful tools for interactive polygon mesh editing result from the most basic descent strategies to solve these optimization problems. Throughout the article, the author develops the mathematical formulations incrementally, keeping in mind that the objective is to implement simple software for interactive editing applications that works well in practice. Readers can implement higher-performance versions of these algorithms by replacing the simple solvers proposed here with more advanced ones. PMID:24806636

  9. Bearing-Only Localization Using Geometrically Constrained Optimization

    E-print Network

    Mao, Guoqiang

    1 Bearing-Only Localization Using Geometrically Constrained Optimization Adrian N. Bishop, Student Member, IEEE, Brian D.O. Anderson, Life Fellow, IEEE, Baris¸ Fidan, Member, IEEE, Pubudu N. Pathirana simulation. Index Terms-- Angle Measurements, Bearings, Geometric Con- straints, Localization, Optimization

  10. Application of separable programming to optimization by geometric programming

    E-print Network

    Humber, Joseph Barker

    1971-01-01

    APPLICATION OI' SEPARABLE PROGPJMMING TO OPTIMIZATION BY GEOMETRIC PROGRAMMING A Thesi. s by Joseph Barker. Number, Jr. Submitted to the Graduate College of Texas ABM Nniversity in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE Dece yber 1971 Majot Subject: Mathematics APPLICATION OF SEPARABLE PROGRAMMING TO OPTIMIZATION BY GEOMETRIC PROGRAMMING A Thesis Joseph Barker Humber, Jr. Approved as to style and content by: (Chairman p Comm Fee/r, & (Member...

  11. Optimization of copper wire bonding on Al-Cu metallization

    Microsoft Academic Search

    Luu T. Nguyen; David McDonald; Anselm R. Danker; Peter Ng

    1995-01-01

    This paper reports the successful implementation of copper wire ball bonding for selected TO-220 devices on a high volume commercial scale. Since August 1992, copper wire bonding has been used in production at National Semiconductor Corp. The development of copper wire ball bonding involves a three-prong approach: optimum pad metal composition, modifications to the wire bonder and optimization of the

  12. Geometric constraint satisfaction using optimization methods

    Microsoft Academic Search

    Jian-xin Ge; Shang-ching Chou; Xiao-shan Gao

    1999-01-01

    The numerical approach to solving geometric constraint problems is indispensable for building a practical CAD system. The most commonly-used numerical method is the Newton-Raphson method. It is fast, but has the instability problem: the method requires good initial values. To overcome this problem, recently the homotopy method has been proposed and experimented with. According to the report, the homotopy method

  13. THP-1 macrophage lipid accumulation unaffected by fatty acid double bond geometric or positional configuration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dietary fatty acid type alters atherosclerotic lesion progression and macrophage lipid accumulation. Incompletely elucidated are the mechanisms by which fatty acids differing in double-bond geometric or positional configuration alter arterial lipid accumulation. The objective of this study was to ev...

  14. Geometric confinement governs the rupture strength of H-bond assemblies at a critical length scale.

    PubMed

    Keten, Sinan; Buehler, Markus J

    2008-02-01

    The ultrastructure of protein materials such as spider silk, muscle tissue, or amyloid fibers consists primarily of beta-sheets structures, composed of hierarchical assemblies of H-bonds. Despite the weakness of H-bond interactions, which have intermolecular bonds 100 to 1000 times weaker than those in ceramics or metals, these materials combine exceptional strength, robustness, and resilience. We discover that the rupture strength of H-bond assemblies is governed by geometric confinement effects, suggesting that clusters of at most 3-4 H-bonds break concurrently, even under uniform shear loading of a much larger number of H-bonds. This universally valid result leads to an intrinsic strength limitation that suggests that shorter strands with less H-bonds achieve the highest shear strength at a critical length scale. The hypothesis is confirmed by direct large-scale full-atomistic MD simulation studies of beta-sheet structures in explicit solvent. Our finding explains how the intrinsic strength limitation of H-bonds can be overcome by the formation of a nanocomposite structure of H-bond clusters, thereby enabling the formation of larger and much stronger beta-sheet structures. Our results explain recent experimental proteomics data, suggesting a correlation between the shear strength and the prevalence of beta-strand lengths in biology. PMID:18269263

  15. A Gentle, Geometric Introduction to Copositive Optimization

    E-print Network

    2015-01-17

    Sep 25, 2014 ... To complete the connection with copositive ... presented will prove useful for solving quadratic problems in practice; some ideas along these lines are mentioned .... three quadratic equations to linearize the objective in (tri): v?. := ...... Sums of squares, moment matrices and optimization over polynomials. In.

  16. Optimal Resource Allocation for Network Protection: A Geometric Programming Approach

    E-print Network

    Plotkin, Joshua B.

    1 Optimal Resource Allocation for Network Protection: A Geometric Programming Approach Victor M the problem of containing spreading processes in arbitrary directed networks by distributing pro- tection resources throughout the nodes of the network. We consider two types of protection resources are available

  17. Bond strength optimization between adherends with different curvatures

    SciTech Connect

    Randow, C.L.; Dillard, D.A. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

    1996-12-31

    Due to the increasing use of adhesives in various industrial applications, the accurate prediction of bond behavior becomes more important. This information may also be used to optimize bond design. In particular, the following analysis focuses on bond geometries involving a curvature mismatch between adherends. For example, consider the profile view of a typical laminated counter-top. This involves bonding an initially flat adherend to a rigid substrate with a flat top, a curved corner of radius {rho}, and a flat landing at the bond edge. Questions arise regarding the behavior of the bond and how to optimize the design to minimize stresses resulting from the initially flat adherend being fixed to the rigid, curved substrate. The deflection of the adherend is modeled using beam on elastic foundation analysis. These results, which can be used to calculate peel stresses, are used to determine the optimal design of the laminated counter-top geometry as presented above. Experimental results are also correlated to the analytical solution.

  18. Printability Optimization For Fine Pitch Solder Bonding

    SciTech Connect

    Kwon, Sang-Hyun; Lee, Chang-Woo; Yoo, Sehoon [Advanced Welding and Joining Technology Center, Korea Institute of Industrial Technology, Incheon, 406-840 (Korea, Republic of)

    2011-01-17

    Effect of metal mask and pad design on solder printability was evaluated by DOE in this study. The process parameters were stencil thickness, squeegee angle, squeegee speed, mask separating speed, and pad angle of PCB. The main process parameters for printability were stencil thickness and squeegee angle. The response surface showed that maximum printability of 1005 chip was achieved at the stencil thickness of 0.12 mm while the maximum printability of 0603 and 0402 chip was obtained at the stencil thickness of 0.05 mm. The bonding strength of the MLCC chips was also directly related with the printability.

  19. Printability Optimization For Fine Pitch Solder Bonding

    NASA Astrophysics Data System (ADS)

    Kwon, Sang-Hyun; Lee, Chang-Woo; Yoo, Sehoon

    2011-01-01

    Effect of metal mask and pad design on solder printability was evaluated by DOE in this study. The process parameters were stencil thickness, squeegee angle, squeegee speed, mask separating speed, and pad angle of PCB. The main process parameters for printability were stencil thickness and squeegee angle. The response surface showed that maximum printability of 1005 chip was achieved at the stencil thickness of 0.12 mm while the maximum printability of 0603 and 0402 chip was obtained at the stencil thickness of 0.05 mm. The bonding strength of the MLCC chips was also directly related with the printability.

  20. Geometric optimization of yield-line patterns using a direct search method

    Microsoft Academic Search

    A. C. A. Ramsay; D. Johnson

    1997-01-01

    A class of problems in the geometric optimization of yield-line patterns, for which the currently advocatedconjugate gradient andsequential linear programming geometric optimization algorithms fail is investigated. TheHooke-Jeeves direct search method is implemented and is demonstrated to solve such problems robustly.

  1. Computer-Aided Design & Applications, Vol. 2, No. 6, 2005, pp 747-758 Geometric Optimization Algorithms in Manufacturing

    E-print Network

    Tang, Kai

    Algorithms in Manufacturing Kai Tang Department of Mechanical Engineering Hong Kong University of Science algorithms for several geometric optimization problems in manufacturing processes. We first describe the strong geometric characteristics of optimization problems in manufacturing. Three illustrative problems

  2. Optimal Attitude Control of a Rigid Body using Geometrically Exact Computations on SO(3)

    Microsoft Academic Search

    Taeyoung Lee; Melvin Leok; N. Harris McClamroch

    2006-01-01

    An efficient and accurate computational approach is proposed for optimal attitude control of a rigid body. The problem is formulated directly as a discrete time optimization problem using a Lie group variational integrator. Discrete necessary conditions for optimality are derived, and an efficient computational approach is proposed to solve the resulting two point boundary value problem. The use of geometrically

  3. Average Case Analysis of Dynamic Geometric Optimization David Eppstein

    E-print Network

    Eppstein, David

    for constructing geometric structures such as convex hulls and arrangements. Such algorithms can also be used on problems of computing geometric structures: convex hulls, arrangements, and the like. However problems algorithms were considerably more complicated. Diameter. The dynamic planar diameter problem can be reduced

  4. A Geometric Analysis of Bang-Bang Extremals in Optimal Control Problems for Combination Cancer Chemotherapy*

    E-print Network

    Ledzewicz, Urszula

    A Geometric Analysis of Bang-Bang Extremals in Optimal Control Problems for Combination Cancer for the models under consideration and thus bang-bang controls become the natural candidates for opti- mality. We use a geometric approach based on the construction of a field of bang-bang extremals to determine

  5. Elsevier Science 1 Front-to back-side overlay optimization after wafer bonding for

    E-print Network

    Technische Universiteit Delft

    Elsevier Science 1 Front- to back-side overlay optimization after wafer bonding for 3D integration; accepted date here Abstract Wafer bonding consists in transferring the device to a new substrate, flipping a technique that makes possible to qualify the wafer bonding in order to know and realize the best achievable

  6. Fine pitch copper wire bonding process optimization with 33µm size ball bond

    Microsoft Academic Search

    Norhanani Binte Jaafar; Wai Leong Ching; Vempati Srinivasa Rao; Chai Tai Chong; Alastair David Trigg; Guna Kanchet; Sivakumar

    2011-01-01

    Gold wire bonding is widely used as the electrical connection or interconnection between the semiconductor component (die) and the package. Bond pads pitch on the device chips are reducing continuously as device technology is moving towards nano-IC technologies. Gold wire is not suitable in the case where the bond pad pitch is less than 50µm because of gold's lower intensity

  7. GEOMETRIC CHARACTERIZATION AND OPTIMIZATION OF 3D ORGANIC FLEXIBLE SOLAR CELLS

    E-print Network

    Kassegne, Samuel Kinde

    GEOMETRIC CHARACTERIZATION AND OPTIMIZATION OF 3D ORGANIC FLEXIBLE SOLAR CELLS Characterization and Optimization of 3D Organic Flexible Solar Cells by Ashish K. Gaikwad Master of Science of flexible organic solar cells, micro-fabricated using novel microfabrication procedures. A fully functional

  8. Discrete Geometric Optimal Control on Lie Groups Marin Kobilarov and Jerrold E. Marsden

    E-print Network

    Kobilarov, Marin

    the state space structure. Among these trajectories we find the extremal one without any further principle to obtain the optimal control trajectory. Such a construction enables the preservation1 Discrete Geometric Optimal Control on Lie Groups Marin Kobilarov and Jerrold E. Marsden Abstract

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

    Microsoft Academic Search

    James Charles Newman III

    1997-01-01

    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

  10. Thermodynamic optimization of geometric structure in the counterflow heat exchanger for an environmental control system

    Microsoft Academic Search

    T. Shiba; A. Bejan

    2001-01-01

    This paper shows that the internal geometric configuration of a component can be deduced by optimizing the global performance of the installation that uses the component. The example chosen is the counterflow heat exchanger that serves as condenser in a vapor-compression-cycle refrigeration system for environmental control of aircraft. The optimization of global performance is achieved by minimizing the total power

  11. Tubular Occlusion Optimizes Bonding of Hydrophobic Resins to Dentin

    Microsoft Academic Search

    F. T. Sadek; D. H. Pashley; M. Ferrari; F. R. Tay

    2007-01-01

    Although hydrophobic resins may be bonded to acid-etched dentin with an ethanol wet-bonding technique, the protocol is sensitive to moisture contamination when bonding is performed in deep dentin. This study tested the hypothesis that the use of oxalate or poly(glutamic) acid-modified, diluted ceramicrete (PADC) for dentinal tubule occlusion prevents fluid contamination and improves the bonding of an experimental hydrophobic adhesive

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    This paper presents a geometric Moir optical-based floating-element shear stress sensor for wind tunnel turbulence measurements. The sensor was fabricated using an aligned wafer-bond/thin-back process producing optical gratings on the backside of a floating element and on the top surface of the support wafer. Measured results indicate a static sensitivity of 0.26 microns/Pa, a resonant frequency of 1.7 kHz, and a noise floor of 6.2 mPa/(square root)Hz.

  13. Catastrophe Bonds, Reinsurance, and the Optimal Collateralization of Risk Transfer

    Microsoft Academic Search

    Darius Lakdawallay; George Zanjani

    2012-01-01

    AbstractCatastrophe bonds feature full collateralization of the underlying risk transfer and thus abandon the reinsurance principle of economizing on collateral through diversification of risk transfer. Our analysis demonstrates that this feature places limits on catastrophe bond penetration, even if the structure possesses frictional cost advantages over reinsurance. However, we also show that catastrophe bonds have important uses when buyers and

  14. Bonding

    MedlinePLUS

    ... is a procedure that uses a tooth-colored composite resin (plastic) to repair a tooth. Bonding can ... cleaned regularly by a dental hygienist. Risks The composite resin used in bonding isn't nearly as ...

  15. Passive vibration control of a satellite boom structure by geometric optimization using genetic algorithm

    Microsoft Academic Search

    M. Moshrefi-Torbati; A. J. Keane; S. J. Elliott; M. J. Brennan; E. Rogers

    2003-01-01

    In this paper, the superior mid-frequency vibration isolation of a geometrically optimized lightweight structure is demonstrated. The initial structure under test here was a 4.5m long satellite boom consisting of 10 identical bays with equilateral triangular cross-sections. An unusual geometric variant of this, with inherent isolation characteristics, has been designed by the use of genetic algorithm (GA) methods. In order

  16. Optimization of Bonding Force, Sinking Value, and Potting Gap Size in COF Inner Lead Bonding Process

    Microsoft Academic Search

    De-Shin Liu; Shu-Shen Yeh; Chun-Teh Kao; Hung-Che Shen; Geng-Shin Shen; Hung-Hsin Liu

    2009-01-01

    The thermo-mechanical properties of the polyimide film used in chip-on-film (COF) packaging have a significant effect on the inner lead bonding (ILB) mechanism. Furthermore, specifying an appropriate bonding force is essential in establishing a suitable compromise between a good bonding strength in the ILB process and a suitable gap size for the subsequent resin potting process. This paper commences by

  17. Joining of Silicon Carbide: Diffusion Bond Optimization and Characterization

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.; Singh, Mrityunjay

    2008-01-01

    Joining and integration methods are critically needed as enabling technologies for the full utilization of advanced ceramic components in aerospace and aeronautics applications. One such application is a lean direct injector for a turbine engine to achieve low NOx emissions. In the application, several SiC substrates with different hole patterns to form fuel and combustion air channels are bonded to form the injector. Diffusion bonding is a joining approach that offers uniform bonds with high temperature capability, chemical stability, and high strength. Diffusion bonding was investigated with the aid of titanium foils and coatings as the interlayer between SiC substrates to aid bonding. The influence of such variables as interlayer type, interlayer thickness, substrate finish, and processing time were investigated. Optical microscopy, scanning electron microscopy, and electron microprobe analysis were used to characterize the bonds and to identify the reaction formed phases.

  18. Convergent synthesis of geometrically disassembling dendrimers using Cu(I)-catalyzed C-O bond formation.

    PubMed

    Polaske, Nathan W; Szalai, Michael L; Shanahan, Charles S; McGrath, Dominic V

    2010-11-01

    The convergent synthesis of geometrically degradable dendrimers based on the 2,4-bis(hydroxymethyl)phenol subunit is presented. The key step of the synthetic scheme involves the CuI/3,4,7,8-tetramethyl-1,10-phenanthroline-catalyzed coupling of aryl iodides and alcohols. The synthesis and disassembly of these compounds is discussed. PMID:20925328

  19. Optimization of the geometrical stability in square ring laser gyroscopes

    E-print Network

    Santagata, R; Belfi, J; Beverini, N; Cuccato, D; Di Virgilio, A; Ortolan, A; Porzio, A; Solimeno, S

    2014-01-01

    Ultra sensitive ring laser gyroscopes are regarded as potential detectors of the general relativistic frame-dragging effect due to the rotation of the Earth: the project name is GINGER (Gyroscopes IN GEneral Relativity), a ground-based triaxial array of ring lasers aiming at measuring the Earth rotation rate with an accuracy of 10^-14 rad/s. Such ambitious goal is now within reach as large area ring lasers are very close to the necessary sensitivity and stability. However, demanding constraints on the geometrical stability of the laser optical path inside the ring cavity are required. Thus we have started a detailed study of the geometry of an optical cavity, in order to find a control strategy for its geometry which could meet the specifications of the GINGER project. As the cavity perimeter has a stationary point for the square configuration, we identify a set of transformations on the mirror positions which allows us to adjust the laser beam steering to the shape of a square. We show that the geometrical s...

  20. Optimal Design of the Adhesively-Bonded Tubular Single Lap Joint

    Microsoft Academic Search

    Su Jeong Lee; Dai Gil Lee

    1995-01-01

    In this paper, a method for the optimal design of the adhesively-bonded tubular single lap joint was proposed based on the failure model of the adhesively-bonded tubular single lap joint. The failure model incorporated the nonlinear mechanical behavior of the adhesive as well as the different failure modes in which the adhesive failure mode changed from bulk shear failure, via

  1. Surface Femtochemistry: Investigation and Optimization of Bond-Forming Chemical Reactions

    NASA Astrophysics Data System (ADS)

    Nuernberger, Patrick; Wolpert, Daniel; Weiss, Horst; Gerber, Gustav

    We investigate femtosecond laser-induced surface reactions by varying the properties of the surface, the reactant gases, and the laser. In optimal control experiments, we selectively manipulate the bond-forming catalytic reactions.

  2. Effect of adherend material stiffness and geometrical stiffness on strength of adhesively bonded joints

    Microsoft Academic Search

    Kiyomi Mori; Hiroaki Isono; Toshio Sugibayashi

    1992-01-01

    The effect of adherend stiffness on the joint strength is examined by varying the adherend material and varying aspect ratio of the adherend dimension. The joint type used in this study is a stepped-lap bonded joint. The joint materials are three kinds of metals, carbon steel, brass and aluminum alloy, for the adherends and an epoxy resin for the adhesive.

  3. Design optimization of geometrically nonlinear truss structures considering cardinality constraints

    Microsoft Academic Search

    Afonso C. C. Lemonge; Michelli M. Silva; Helio J. C. Barbosa

    2011-01-01

    The structural optimization problem of choosing the profile of each member belonging to a framed structure in order to minimize its weight while satisfying stress, displacement, stability, and other applicable constraints is often complicated by the requirement of considering non-linear structural behavior. The problem is further complicated if the members are to be chosen from a discrete set of commercially

  4. Thermal simulation for geometric optimization of metallized polypropylene film capacitors

    Microsoft Academic Search

    M. H. El-Husseini; Pascal Venet; Gérard Rojat; Charles Joubert

    2002-01-01

    In this paper, the authors use an analytical model to calculate the losses in the metallized polypropylene film capacitors. The model is validated experimentally for capacitors having the same capacitance but different geometry. For each group of capacitors, a temperature distribution in the roll is assumed with the aim of optimizing its thermal performance. It appears that the heating of

  5. Analysis of practical slab configurations using automated yield-line analysis and geometric optimization of fracture patterns

    Microsoft Academic Search

    A. C. A. Ramsay; D. Johnson

    1998-01-01

    Automated yield-line analysis and geometric optimization are used in the analysis and design of a number of practical reinforced concrete slab configurations. For two of the chosen configurations comparisons between experimental and theoretical results are possible. The final configuration is included to illustrate the significance and importance of carrying out some form of geometric optimization.

  6. Some Geometric Optimization Problems in Wireless Networks Nissan LevTov #

    E-print Network

    Barash, Danny

    Some Geometric Optimization Problems in Wireless Networks Nissan Lev­Tov # I will present some new aspects of ad­hoc and sensor networks, where the set of chosen piercing points can be used coloring of unit disks in the plane, and talk about its applications to frequency assignment in wireless

  7. Geometric Algorithms for Optimal Airspace Design and Air Traffic Controller Workload Balancing

    E-print Network

    Mitchell, Joseph S.B.

    Geometric Algorithms for Optimal Airspace Design and Air Traffic Controller Workload Balancing America. For purposes of workload limitations for air traffic controllers, the airspace is partitioned by one or more air traffic controllers (or a small team of 1-3 controllers) at any given time of the day

  8. Fluence Map Optimization in IMRT Cancer Treatment Planning and A Geometric Approach

    E-print Network

    Zhang, Yin

    therapy (IMRT) is a state-of-the-art technique for administering radiation to cancer patients. The goal radiation therapy, Optimal treatment planning, Fluence map op- timization, A geometric Approach eventually recover. Therefore, research in radiation therapy seeks methods of delivering a sufficient dose

  9. Geometric H\\/D Isotope Effects and Cooperativity of the Hydrogen Bonds in Porphycene

    Microsoft Academic Search

    Mohamed F. Shibl; Mariusz Pietrzak; Hans-Heinrich Limbach; Oliver K hn

    2007-01-01

    We investigate the primary, secondary, and vicinal hydrogen\\/deu- terium (H\\/D) isotope effects on the geometry of the two intramo- lecular hydrogen bonds in porphycene. Multidimensional poten- tial energy surfaces describing the anharmonic motion in the vi- cinity of the trans isomer are calculatedfor the d ifferent symmet- ric (HH\\/DD) andasymmetric (HD) isotopomers. From the solution of the nuclear Schrçdinger equation

  10. Optimal Resource Allocation for Network Protection: A Geometric Programming Approach

    E-print Network

    Preciado, Victor M; Enyioha, Chinwendu; Jadbabaie, Ali; Pappas, George

    2013-01-01

    We study the problem of containing spreading processes in arbitrary directed networks by distributing protection resources throughout the nodes of the network. We consider two types of protection resources are available: (i) Preventive resources able to defend nodes against the spreading (such as vaccines in a viral infection process), and (ii) corrective resources able to neutralize the spreading after it has reached a node (such as antidotes). We assume that both preventive and corrective resources have an associated cost and study the problem of finding the cost-optimal distribution of resources throughout the nodes of the network. We analyze these questions in the context of viral spreading processes in directed networks. We study the following two problems: (i) Given a fixed budget, find the optimal allocation of preventive and corrective resources in the network to achieve the highest level of containment, and (ii) when a budget is not specified, find the minimum budget required to control the spreading...

  11. Geometric versus numerical optimal control of a dissipative spin-(1/2) particle

    SciTech Connect

    Lapert, M.; Sugny, D. [Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 5209 CNRS-Universite de Bourgogne, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Zhang, Y.; Braun, M.; Glaser, S. J. [Department of Chemistry, Technische Universitaet Muenchen, Lichtenbergstrasse 4, D-85747 Garching (Germany)

    2010-12-15

    We analyze the saturation of a nuclear magnetic resonance (NMR) signal using optimal magnetic fields. We consider both the problems of minimizing the duration of the control and its energy for a fixed duration. We solve the optimal control problems by using geometric methods and a purely numerical approach, the grape algorithm, the two methods being based on the application of the Pontryagin maximum principle. A very good agreement is obtained between the two results. The optimal solutions for the energy-minimization problem are finally implemented experimentally with available NMR techniques.

  12. Cooperative Effects and Optimal Halogen Bonding Motifs for Self-Assembling Systems

    PubMed Central

    2015-01-01

    Halogen bonding, due to its directionality and tunable strength, is being increasingly utilized in self-assembling materials and crystal engineering. Using density functional theory (DFT) and molecular mechanics (OPLS/CM1Ax) calculations, multiply halogen bonded complexes of brominated imidazole and pyridine are investigated along with their potential in construction of self-assembling architectures. Dimers with 1–10 halogen bonds are considered and reveal maximal binding energies of 3–36 kcal/mol. Cooperative (nonadditive) effects are found in complexes that extend both along and perpendicular to the halogen bonding axes, with interaction energies depending on polarization, secondary interactions, and ring spacers. Four structural motifs were identified to yield optimal halogen bonding. For the largest systems, the excellent agreement found between the DFT and OPLS/CM1Ax results supports the utility of the latter approach for analysis and design of self-assembling supramolecular structures. PMID:24678636

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  14. Using neural networks and immune algorithms to find the optimal parameters for an IC wire bonding process

    Microsoft Academic Search

    Chi-hung Su; Hung-zhi Chang

    2008-01-01

    The wire bonding process is the key process in an IC chip-package. It is an urgent problem for IC chip-package industry to improve the wire bonding process capability. In this study, an integration of artificial neural networks (ANN) with artificial immune systems (AIS) is proposed to optimize parameters for an IC wire bonding process. The algorithm of AIS with memory

  15. Geometrical shape optimization of a cold neutron source using artificial intelligence strategies

    SciTech Connect

    Azmy, Y.Y.

    1989-01-01

    A new approach is developed for optimizing the geometrical shape of a cold neutron source to maximize its cold neutron outward leakage. An analogy is drawn between the shape optimization problem and a state space search, which is the fundamental problem in Artificial Intelligence applications. The new optimization concept is implemented in the computer code DAIT in which the physical model is represented by a two group, r-z geometry nodal diffusion method, and the state space search is conducted via the Nearest Neighbor algorithm. The accuracy of the nodal diffusion method solution is established on meshes of interest, and is shown to behave qualitatively the same as transport theory solutions. The dependence of the optimum shape and its value on several physical and search parameters is examined via numerical experimentation. 10 refs., 6 figs., 2 tabs.

  16. Implementation and Optimization of miniGMG - a Compact Geometric Multigrid Benchmark

    SciTech Connect

    Williams, Samuel; Kalamkar, Dhiraj; Singh, Amik; Deshpande, Anand M.; Straalen, Brian Van; Smelyanskiy, Mikhail; Almgren, Ann; Dubey, Pradeep; Shalf, John; Oliker, Leonid

    2012-12-01

    Multigrid methods are widely used to accelerate the convergence of iterative solvers for linear systems used in a number of different application areas. In this report, we describe miniGMG, our compact geometric multigrid benchmark designed to proxy the multigrid solves found in AMR applications. We explore optimization techniques for geometric multigrid on existing and emerging multicore systems including the Opteron-based Cray XE6, Intel Sandy Bridge and Nehalem-based Infiniband clusters, as well as manycore-based architectures including NVIDIA's Fermi and Kepler GPUs and Intel's Knights Corner (KNC) co-processor. This report examines a variety of novel techniques including communication-aggregation, threaded wavefront-based DRAM communication-avoiding, dynamic threading decisions, SIMDization, and fusion of operators. We quantify performance through each phase of the V-cycle for both single-node and distributed-memory experiments and provide detailed analysis for each class of optimization. Results show our optimizations yield significant speedups across a variety of subdomain sizes while simultaneously demonstrating the potential of multi- and manycore processors to dramatically accelerate single-node performance. However, our analysis also indicates that improvements in networks and communication will be essential to reap the potential of manycore processors in large-scale multigrid calculations.

  17. Light scattering measurements for quantifying biological cell concentration: an optimization of opto-geometric parameters

    NASA Astrophysics Data System (ADS)

    Mignani, A. G.; Ciaccheri, L.; Giannelli, L.; Mencaglia, A. A.

    2012-03-01

    An experimental study was carried out, aimed at optimizing the optical/geometrical configuration for measuring the concentration of biological cells by means of static light scattering measurements. A LED-based optoelectronic setup making use of optical fibers was experimented, as the precursor of a low-cost device to be integrated in instrumentation for cytometry. Two biological sample types were considered as test samples of the most popular analyses - cervical cells and urine, respectively. The most suitable wavelengths and detecting angles were identified, and calibration curves were calculated.

  18. Light scattering measurements for quantifying biological cell concentration: an optimization of opto-geometric parameters

    NASA Astrophysics Data System (ADS)

    Mignani, A. G.; Ciaccheri, L.; Mencaglia, A. A.; Giannelli, L.

    2011-05-01

    An experimental study was carried out, aimed at optimizing the optical/geometrical configuration for measuring the concentration of biological cells by means of static light scattering measurements. A LED-based optoelectronic setup making use of optical fibers was experimented, as the precursor of a low-cost device to be integrated in instrumentation for cytometry. Two biological sample types were considered as test samples of the most popular analyses - cervical cells and urine, respectively. The most suitable wavelengths and detecting angles were identified, and calibration curves were calculated.

  19. IEEE TRANSACTIONS ON ROBOTICS, VOL. 27, NO. 4, AUGUST 2011 641 Discrete Geometric Optimal Control on Lie Groups

    E-print Network

    Kobilarov, Marin

    these trajectories, we find the extremal one without any further discretization or approximation. This is achieved principle to obtain the optimal control trajectory. Such a construction enables the preservation of imIEEE TRANSACTIONS ON ROBOTICS, VOL. 27, NO. 4, AUGUST 2011 641 Discrete Geometric Optimal Control

  20. Optimal geometrical design for superhydrophobic surfaces: effects of a trapezoid microtexture.

    PubMed

    Li, W; Cui, X S; Fang, G P

    2010-03-01

    It is now becoming possible to control and tailor micro/nanoscale chemical structures with different geometrical patterns on various substrates to achieve so-called superhydrophobic surfaces, which show promising industrial applications. In spite of significant advances in preparation of such surfaces, to date the effects of surface patterns or geometries on superhydrophobicity have not been understood completely, in particular, in the theoretical aspect. It has therefore been a challenge to design optimal geometry for ideal superhydrophobic behavior. In this study, a trapezoid microtextured superhydrophobic surface has been thermodynamically analyzed using a 2-D model. Furthermore, based on the calculations of free energy (FE) and free energy barrier (FEB), the effects of all the geometrical parameters for the trapezoid microtexture on contact angle (CA) and contact angle hysteresis (CAH) have been investigated systematically. It is demonstrated that besides height, base angle plays a significant important role in equilibrium contact angle (ECA) and CAH; in particular, a critical base angle for the present geometrical system is necessary for the transition from noncomposite to composite states. Moreover, the trapezoid base width affects strongly various CAs; a small base width is necessary for the large ECA and the small CAH. However, the effects of trapezoid base spacing are considerably complex. For the above transition, a small base spacing is necessary, but decreasing base spacing can decrease the ECA only for the composite state and can increase CAH only for the noncomposite state. Based on the above findings, some fundamental principles for the design of optimal geometry of ideal superhydrophobic surfaces are therefore suggested, which are also consistent with the experimental observations and previous theoretical investigations. PMID:20112932

  1. Geometric parameter analysis to predetermine optimal radiosurgery technique for the treatment of arteriovenous malformation

    SciTech Connect

    Mestrovic, Ante [Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia (Canada) and Department of Medical Physics, British Columbia Cancer Agency, Vancouver, British Columbia (Canada)]. E-mail: amestrovic@bccancer.bc.ca; Clark, Brenda G. [Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia (Canada); Department of Medical Physics, British Columbia Cancer Agency, Vancouver, British Columbia (Canada)

    2005-11-01

    Purpose: To develop a method of predicting the values of dose distribution parameters of different radiosurgery techniques for treatment of arteriovenous malformation (AVM) based on internal geometric parameters. Methods and Materials: For each of 18 previously treated AVM patients, four treatment plans were created: circular collimator arcs, dynamic conformal arcs, fixed conformal fields, and intensity-modulated radiosurgery. An algorithm was developed to characterize the target and critical structure shape complexity and the position of the critical structures with respect to the target. Multiple regression was employed to establish the correlation between the internal geometric parameters and the dose distribution for different treatment techniques. The results from the model were applied to predict the dosimetric outcomes of different radiosurgery techniques and select the optimal radiosurgery technique for a number of AVM patients. Results: Several internal geometric parameters showing statistically significant correlation (p < 0.05) with the treatment planning results for each technique were identified. The target volume and the average minimum distance between the target and the critical structures were the most effective predictors for normal tissue dose distribution. The structure overlap volume with the target and the mean distance between the target and the critical structure were the most effective predictors for critical structure dose distribution. The predicted values of dose distribution parameters of different radiosurgery techniques were in close agreement with the original data. Conclusions: A statistical model has been described that successfully predicts the values of dose distribution parameters of different radiosurgery techniques and may be used to predetermine the optimal technique on a patient-to-patient basis.

  2. WIRE BONDING PARAMETERS OPTIMIZATION AND YIELD ENHANCEMENT FOR SILICON RECTIFICATION DIODE

    Microsoft Academic Search

    Yu-Min Chiang; Huei-Min Chiang; Yu-Wei Cheng

    The research pays attention to the wire bonding (W\\/B) manufacturing process of TO series products of silicon rectification diode because W\\/B plays a key role on product yield. The study applied the Taguchi method to determine the optimal parameters of W\\/B process. The confirmation experiment validates that the average defect rate of W\\/B has decreased from 35.75% to 10.75% and

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

    PubMed Central

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

    2014-01-01

    Nutrient balance is a strong determinant of animal fitness and demography. It is therefore important to understand how the compositions of available foods relate to required balance of nutrients and habitat suitability for animals in the wild. These relationships are, however, complex, particularly for omnivores that often need to compose balanced diets by combining their intake from diverse nutritionally complementary foods. Here we apply geometric models to understand how the nutritional compositions of foods available to an omnivorous member of the order Carnivora, the grizzly bear (Ursus arctos L.), relate to optimal macronutrient intake, and assess the seasonal nutritional constraints on the study population in west-central Alberta, Canada. The models examined the proportion of macronutrients that bears could consume by mixing their diet from food available in each season, and assessed the extent to which bears could consume the ratio of protein to non-protein energy previously demonstrated using captive bears to optimize mass gain. We found that non-selective feeding on ungulate carcasses provided a non-optimal macronutrient balance with surplus protein relative to fat and carbohydrate, reflecting adaptation to an omnivorous lifestyle, and that optimization through feeding selectively on different tissues of ungulate carcasses is unlikely. Bears were, however, able to dilute protein intake to an optimal ratio by mixing their otherwise high-protein diet with carbohydrate-rich fruit. Some individual food items were close to optimally balanced in protein to non-protein energy (e.g. Hedysarum alpinum roots), which may help explain their dietary prevalence. Ants may be consumed particularly as a source of lipids. Overall, our analysis showed that most food available to bears in the study area were high in protein relative to lipid or carbohydrate, suggesting the lack of non-protein energy limits the fitness (e.g. body size and reproduction) and population density of grizzly bears in this ecosystem. PMID:24841821

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

    PubMed

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

    2014-01-01

    Nutrient balance is a strong determinant of animal fitness and demography. It is therefore important to understand how the compositions of available foods relate to required balance of nutrients and habitat suitability for animals in the wild. These relationships are, however, complex, particularly for omnivores that often need to compose balanced diets by combining their intake from diverse nutritionally complementary foods. Here we apply geometric models to understand how the nutritional compositions of foods available to an omnivorous member of the order Carnivora, the grizzly bear (Ursus arctos L.), relate to optimal macronutrient intake, and assess the seasonal nutritional constraints on the study population in west-central Alberta, Canada. The models examined the proportion of macronutrients that bears could consume by mixing their diet from food available in each season, and assessed the extent to which bears could consume the ratio of protein to non-protein energy previously demonstrated using captive bears to optimize mass gain. We found that non-selective feeding on ungulate carcasses provided a non-optimal macronutrient balance with surplus protein relative to fat and carbohydrate, reflecting adaptation to an omnivorous lifestyle, and that optimization through feeding selectively on different tissues of ungulate carcasses is unlikely. Bears were, however, able to dilute protein intake to an optimal ratio by mixing their otherwise high-protein diet with carbohydrate-rich fruit. Some individual food items were close to optimally balanced in protein to non-protein energy (e.g. Hedysarum alpinum roots), which may help explain their dietary prevalence. Ants may be consumed particularly as a source of lipids. Overall, our analysis showed that most food available to bears in the study area were high in protein relative to lipid or carbohydrate, suggesting the lack of non-protein energy limits the fitness (e.g. body size and reproduction) and population density of grizzly bears in this ecosystem. PMID:24841821

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

    ERIC Educational Resources Information Center

    Magnasco, Valerio

    2008-01-01

    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…

  6. Special two-dimensional and three-dimensional geometrically nonlinear finite elements for analysis of adhesively bonded joints

    Microsoft Academic Search

    Raul Horacio Andruet

    1998-01-01

    Finite element models have been successfully used to analyze adhesive bonds in actual structures, but this takes a considerable amount of time and a high computational cost. The objective of this study is to develop a simple and cost-effective finite element model for adhesively bonded joints which could be used in industry. Stress and durability analyses of crack patch geometries

  7. GNSS tomography and optimal geometrical setting to retrieve water vapour density of the neutral atmosphere

    NASA Astrophysics Data System (ADS)

    Brenot, Hugues; Errera, Quentin; Champollion, Cédric; Verhoelst, Tijl; Kumps, Nicolas; Van Malderen, Roeland; Van Roozendael, Michel

    2014-05-01

    Day by day, the number of GNSS satellites, ground receivers and slant observations are increasing. From these measurements a better monitoring of the water vapour of the neutral atmosphere is expected using tomographic imaging. For the moment the limitation of GNSS tomography is still due to a weak geometric representation. For this reason, this study will present some tests about the sensitivity of tomographic retrievals to different geometry of network and to different vertical and horizontal distributions of the adjusted volumic pixels (voxels). Using a synthetic approach (slant water vapour contents simulated from numerical atmospheric model outputs, e.g. ERA-interim and BASCOE) to retrieve information about the water vapour of different layers of the neutral atmosphere, this study will show the respective optimal geometrical setting of GNSS tomography. A validation of these configurations will be shown using real GNSS observations of SIWV (established from ZTD and gradients) and tomographic retrievals compared to profiles from radiosondes and sun-synchronous satellites sensors (i.e. IASI on MetOp-A and MLS on Aura).

  8. Riemannian geometric approach to human arm dynamics, movement optimization, and invariance

    NASA Astrophysics Data System (ADS)

    Biess, Armin; Flash, Tamar; Liebermann, Dario G.

    2011-03-01

    We present a generally covariant formulation of human arm dynamics and optimization principles in Riemannian configuration space. We extend the one-parameter family of mean-squared-derivative (MSD) cost functionals from Euclidean to Riemannian space, and we show that they are mathematically identical to the corresponding dynamic costs when formulated in a Riemannian space equipped with the kinetic energy metric. In particular, we derive the equivalence of the minimum-jerk and minimum-torque change models in this metric space. Solutions of the one-parameter family of MSD variational problems in Riemannian space are given by (reparametrized) geodesic paths, which correspond to movements with least muscular effort. Finally, movement invariants are derived from symmetries of the Riemannian manifold. We argue that the geometrical structure imposed on the arm’s configuration space may provide insights into the emerging properties of the movements generated by the motor system.

  9. Uncoiling Mechanics of Escherichia coli Type I Fimbriae Are Optimized for Catch Bonds

    PubMed Central

    Forero, Manu; Yakovenko, Olga; Sokurenko, Evgeni V; Thomas, Wendy E; Vogel, Viola

    2006-01-01

    We determined whether the molecular structures through which force is applied to receptor–ligand pairs are tuned to optimize cell adhesion under flow. The adhesive tethers of our model system, Escherichia coli, are type I fimbriae, which are anchored to the outer membrane of most E. coli strains. They consist of a fimbrial rod (0.3–1.5 ?m in length) built from a helically coiled structural subunit, FimA, and an adhesive subunit, FimH, incorporated at the fimbrial tip. Previously reported data suggest that FimH binds to mannosylated ligands on the surfaces of host cells via catch bonds that are enhanced by the shear-originated tensile force. To understand whether the mechanical properties of the fimbrial rod regulate the stability of the FimH–mannose bond, we pulled the fimbriae via a mannosylated tip of an atomic force microscope. Individual fimbriae rapidly elongate for up to 10 ?m at forces above 60 pN and rapidly contract again at forces below 25 pN. At intermediate forces, fimbriae change length more slowly, and discrete 5.0 ± 0.3–nm changes in length can be observed, consistent with uncoiling and coiling of the helical quaternary structure of one FimA subunit at a time. The force range at which fimbriae are relatively stable in length is the same as the optimal force range at which FimH–mannose bonds are longest lived. Higher or lower forces, which cause shorter bond lifetimes, cause rapid length changes in the fimbria that help maintain force at the optimal range for sustaining the FimH–mannose interaction. The modulation of force and the rate at which it is transmitted from the bacterial cell to the adhesive catch bond present a novel physiological role for the fimbrial rod in bacterial host cell adhesion. This suggests that the mechanical properties of the fimbrial shaft have codeveloped to optimize the stability of the terminal adhesive under flow. PMID:16933977

  10. Computationally-validated surrogate models for optimal geometric design of bio-inspired swimming robots: Helical swimmers

    E-print Network

    Yanikoglu, Berrin

    fluid dynamics (CFD) simulation or an experiment. Results of the RFT-based hydrodynamic modelComputationally-validated surrogate models for optimal geometric design of bio-inspired swimming history: Received 21 October 2013 Received in revised form 4 April 2014 Accepted 29 April 2014 Available

  11. Supramolecular architectures on surfaces formed through hydrogen bonding optimized in three dimensions.

    PubMed

    Yu, Miao; Kalashnyk, Nataliya; Xu, Wei; Barattin, Régis; Benjalal, Youness; Laegsgaard, Erik; Stensgaard, Ivan; Hliwa, Mohamed; Bouju, Xavier; Gourdon, André; Joachim, Christian; Besenbacher, Flemming; Linderoth, Trolle R

    2010-07-27

    Supramolecular self-assembly on surfaces, guided by hydrogen bonding interactions, has been widely studied, most often involving planar compounds confined directly onto surfaces in a planar two-dimensional (2-D) geometry and equipped with structurally rigid chemical functionalities to direct the self-assembly. In contrast, so-called molecular Landers are a class of compounds that exhibit a pronounced three-dimensional (3-D) structure once adsorbed on surfaces, arising from a molecular backboard equipped with bulky groups which act as spacer legs. Here we demonstrate the first examples of extended, hydrogen-bonded surface architectures formed from molecular Landers. Using high-resolution scanning tunnelling microscopy (STM) under well controlled ultrahigh vacuum conditions we characterize both one-dimensional (1-D) chains as well as five distinct long-range ordered 2-D supramolecular networks formed on a Au(111) surface from a specially designed Lander molecule equipped with dual diamino-triazine (DAT) functional moieties, enabling complementary NH...N hydrogen bonding. Most interestingly, comparison of experimental results to STM image calculations and molecular mechanics structural modeling demonstrates that the observed molecular Lander-DAT structures can be rationalized through characteristic intermolecular hydrogen bonding coupling motifs which would not have been possible in purely planar 2-D surface assembly because they involve pronounced 3-D optimization of the bonding configurations. The described 1-D and 2-D patterns of Lander-DAT molecules may potentially be used as extended molecular molds for the nucleation and growth of complex metallic nanostructures. PMID:20550141

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

    SciTech Connect

    Chang,X.; Ben-Zvi, I.

    2008-10-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Newman, James Charles, III

    1997-10-01

    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 with a structured-grid approach, is their inherent ability to discretize irregularly shaped domains with greater efficiency and less effort. Hence, this approach is ideally suited for geometrically complex configurations of practical interest. In this work the time-dependent, nonlinear Euler equations are solved using an upwind, cell-centered, finite-volume scheme. The discrete, linearized systems which result from this scheme are solved iteratively by a preconditioned conjugate-gradient-like algorithm known as GMRES for the two-dimensional cases and a Gauss-Seidel algorithm for the three-dimensional; at steady-state, similar procedures are used to solve the accompanying linear aerodynamic sensitivity equations in incremental iterative form. As shown, this particular form of the sensitivity equation makes large-scale gradient-based aerodynamic optimization possible by taking advantage of memory efficient methods to construct exact Jacobian matrix-vector products. Various surface parameterization techniques have been employed in the current study to control the shape of the design surface. Once this surface has been deformed, the interior volume of the unstructured grid is adapted by considering the mesh as a system of interconnected tension springs. Grid sensitivities are obtained by differentiating the surface parameterization and the grid adaptation algorithms with ADIFOR, an advanced automatic-differentiation software tool. To demonstrate the ability of this procedure to analyze and design complex configurations of practical interest, the sensitivity analysis and shape optimization has been performed for several two- and three-dimensional cases. In twodimensions, an initially symmetric NACA-0012 airfoil and a high-lift multielement airfoil were examined. For the three-dimensional configurations, an initially rectangular wing with uniform NACA-0012 cross-sections was optimized; in addition, a complete Boeing 747-200 aircraft was studied. Furthermore, the current study also examines the effect of inconsistency in the order of spatial accuracy between the nonlinear fluid and linear shape sensitivity equations. The second step was to develop a computationally efficient, high-fidelity, integrated static aeroelastic analysis procedure. To accomplish this, a structural analysis code was coupled with the aforementioned unstructured grid aerodynamic analysis solver. The use of an unstructured grid scheme for the aerodynamic analysis enhances the interaction compatibility with the wing structure. The structural analysis utilizes finite elements to model the wing so that accurate structural deflections may be obtained. In the current work, parameters have been introduced to control the interaction of the computational fluid dynamics and structural analyses; these control parameters permit extremely efficient static aeroelastic computations. To demonstrate and evaluate this procedure, static aeroelastic analysis results for a flexible wing in low subsonic, high subsonic (subcritical), transonic (supercritical), and supersonic flow conditions are presented.

  14. Incorporating geometric ray tracing to generate initial conditions for intensity modulated arc therapy optimization

    SciTech Connect

    Oliver, Mike; Gladwish, Adam; Craig, Jeff; Chen, Jeff; Wong, Eugene [Department of Medical Biophysics, University of Western Ontario, London, Ontario, N6A 5C1 (Canada); Department of Physics and Engineering, London Regional Cancer Program, London Health Sciences Centre, London, Ontario, N6A 4L6 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario, N6A 5C1 (Canada); Department of Oncology, University of Western Ontario, London, Ontario, N6A 4L6 (Canada) and Department of Physics and Engineering, London Regional Cancer Program, London Health Sciences Centre, London, Ontario, N6A 4L6 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario, N6A 5C1 (Canada); Department of Oncology, University of Western Ontario, London, Ontario, N6A 4L6 (Canada); Department of Physics and Engineering, London Regional Cancer Program, London Health Sciences Centre, London, Ontario, N6A 4L6 (Canada) and Department of Physics and Astronomy, University of Western Ontario, London, Ontario, N6A 3K7 (Canada)

    2008-07-15

    Purpose and background: Intensity modulated arc therapy (IMAT) is a rotational variant of Intensity modulated radiation therapy (IMRT) that is achieved by allowing the multileaf collimator (MLC) positions to vary as the gantry rotates around the patient. This work describes a method to generate an IMAT plan through the use of a fast ray tracing technique based on dosimetric and geometric information for setting initial MLC leaf positions prior to final IMAT optimization. Methods and materials: Three steps were used to generate an IMAT plan. The first step was to generate arcs based on anatomical contours. The second step was to generate ray importance factor (RIF) maps by ray tracing the dose distribution inside the planning target volume (PTV) to modify the MLC leaf positions of the anatomical arcs to reduce the maximum dose inside the PTV. The RIF maps were also segmented to create a new set of arcs to improve the dose to low dose voxels within the PTV. In the third step, the MLC leaf positions from all arcs were put through a leaf position optimization (LPO) algorithm and brought into a fast Monte Carlo dose calculation engine for a final dose calculation. The method was applied to two phantom cases, a clinical prostate case and the Radiological Physics Center (RPC)'s head and neck phantom. The authors assessed the plan improvements achieved by each step and compared plans with and without using RIF. They also compared the IMAT plan with an IMRT plan for the RPC phantom. Results: All plans that incorporated RIF and LPO had lower objective function values than those that incorporated LPO only. The objective function value was reduced by about 15% after the generation of RIF arcs and 52% after generation of RIF arcs and leaf position optimization. The IMAT plan for the RPC phantom had similar dose coverage for PTV1 and PTV2 (the same dose volume histogram curves), however, slightly lower dose to the normal tissues compared to a six-field IMRT plan. Conclusion: The use of a ray importance factor can generate initial IMAT arcs efficiently for further MLC leaf position optimization to obtain more favorable IMAT plan.

  15. Optimization of gold wire bonding on electroless nickel immersion gold for high temperature applications

    Microsoft Academic Search

    Beng Teck Ng; V. P. Ganesh; C. Lee

    2006-01-01

    Conventional gold (Au) wire bonding on aluminum (Al) bond pads leads to the formation of intermetallic compounds. During high temperature exposure, associated Kirkendall voids formed in the intermetallic phases (IMP) can degrade reliability of the interconnect. The advert of green molding compounds has exacerbated the ball bond reliability with Al bond pad. Thus there is a need for alternative bond

  16. Methodology for optimal configuration in structural health monitoring of composite bonded joints

    NASA Astrophysics Data System (ADS)

    Quaegebeur, N.; Micheau, P.; Masson, P.; Castaings, M.

    2012-10-01

    In this study, a structural health monitoring (SHM) strategy is proposed in order to detect disbonds in a composite lap-joint. The structure under study is composed of a carbon fiber reinforced polymer (CFRP) bonded to a titanium plate and artificial disbonds are simulated by inserting Teflon tapes of various dimensions within the joint. In situ inspection is ensured by piezoceramics bonded to the structure to generate and measure guided waves. Theoretical propagation and through-thickness stress distribution are first studied in order to determine damage sensitivity with respect to the mode and frequency of the generated guided wave. The optimal configuration of the system in terms of piezoceramic size, shape and inter-unit spacing is then validated using finite element modeling (FEM) in 3D. Experimental assessment of propagation characteristics is conducted using laser Doppler vibrometer (LDV) in order to justify theoretical and numerical assumptions and pitch-catch measurements are then performed to validate the efficient detection of the damage and accurate estimation of its size.

  17. Geometrical stiffness and sensitivity matrices for optimization of semi-rigid steel frameworks

    Microsoft Academic Search

    L. Xu

    1992-01-01

    A geometrical stiffness matrix for a flexibly-connected member is developed for the analysis and design of semirigid framed structures when geometrical non-linearity (P — ? effects and other second-order effects) must be considered. A “fixity factor” defining the rigidity of a connection relative to the attached member is introduced to model different types of member connectivity. The sensitivities of the

  18. A Geometric Characterization of the Power of Finite Adaptability in Multistage Stochastic and Adaptive Optimization

    E-print Network

    Bertsimas, Dimitris J.

    In this paper, we show a significant role that geometric properties of uncertainty sets, such as symmetry, play in determining the power of robust and finitely adaptable solutions in multistage stochastic and adaptive ...

  19. An optimized teflon bonding process for solar cell assemblies using Pilkington CMZ and CMG coverglasses

    Microsoft Academic Search

    K Mullaneyl; A. A. Dollery; G. M. Jones; K. Bogus

    1993-01-01

    Attempts at teflon bonding have always failed due to the mismatch of thermal coefficients of expansion. With the advent of the Pilkington CMZ and CMG coverglasses where the coefficients have been exactly matched to the solar cell material, the bonding process has been developed so that the advantages and disadvantages of teflon bonding may be evaluated for use in the

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

    Microsoft Academic Search

    Chao-Ton Su; Cheng-Jung Yeh

    2011-01-01

    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

  1. Calculation of geometric and electronic structure of Mg porphyrins in optimal spd' bases

    SciTech Connect

    Mamaev, V.M.; Babin, Y.V.; Gloriokov, I.F.; Orlov, V.V.

    1985-12-01

    The authors investigate the construction of models of the photosynthetic machinery on the molecular level, which requires information on the geometric and electronic structure and the energy characteristics of Mg chlorins, Mg bacteriochlorins, and complexes with axial ligands. They present results of calculations of the geometric and electronic structures which are significantly dependent on the values of the exponents used in the case of compounds containing an Mg atom with a coordination number greater than 2. A method for the determination of spd' bases has been developed, and the geometric and electronic structures of MgChl and MgBChl and their aquo complexes have been studied. The high efficiency of the photosynthesis process has stimulated attempts to create molecular systems like chlorophyll for the conversion of solar energy.

  2. Optimizing wind farm layout via LES-calibrated geometric models inclusive of wind direction and atmospheric stability effects

    NASA Astrophysics Data System (ADS)

    Archer, Cristina; Ghaisas, Niranjan

    2015-04-01

    The energy generation at a wind farm is controlled primarily by the average wind speed at hub height. However, two other factors impact wind farm performance: 1) the layout of the wind turbines, in terms of spacing between turbines along and across the prevailing wind direction; staggering or aligning consecutive rows; angles between rows, columns, and prevailing wind direction); and 2) atmospheric stability, which is a measure of whether vertical motion is enhanced (unstable), suppressed (stable), or neither (neutral). Studying both factors and their complex interplay with Large-Eddy Simulation (LES) is a valid approach because it produces high-resolution, 3D, turbulent fields, such as wind velocity, temperature, and momentum and heat fluxes, and it properly accounts for the interactions between wind turbine blades and the surrounding atmospheric and near-surface properties. However, LES are computationally expensive and simulating all the possible combinations of wind directions, atmospheric stabilities, and turbine layouts to identify the optimal wind farm configuration is practically unfeasible today. A new, geometry-based method is proposed that is computationally inexpensive and that combines simple geometric quantities with a minimal number of LES simulations to identify the optimal wind turbine layout, taking into account not only the actual frequency distribution of wind directions (i.e., wind rose) at the site of interest, but also atmospheric stability. The geometry-based method is calibrated with LES of the Lillgrund wind farm conducted with the Software for Offshore/onshore Wind Farm Applications (SOWFA), based on the open-access OpenFOAM libraries. The geometric quantities that offer the best correlations (>0.93) with the LES results are the blockage ratio, defined as the fraction of the swept area of a wind turbine that is blocked by an upstream turbine, and the blockage distance, the weighted distance from a given turbine to all upstream turbines that can potentially block it. Based on blockage ratio and distance, an optimization procedure is proposed that explores many different layout variables and identifies, given actual wind direction and stability distributions, the optimal wind farm layout, i.e., the one with the highest wind energy production. The optimization procedure is applied to both the calibration wind farm (Lillgrund) and a test wind farm (Horns Rev) and a number of layouts more efficient than the existing ones are identified. The optimization procedure based on geometric models proposed here can be applied very quickly (within a few hours) to any proposed wind farm, once enough information on wind direction frequency and, if available, atmospheric stability frequency has been gathered and once the number of turbines and/or the areal extent of the wind farm have been identified.

  3. Dynamic Half-Space Reporting, Geometric Optimization, and Minimum Spanning Trees

    E-print Network

    Eppstein, David

    efficient dynamic algorithms for a num- ber of geometric problems, including closest/farthest neighbor searching, fixed dimension linear program- ming, bi-chromatic closest pair, diameter, and Eu- clidean efficient dynamic algorithms either for a similar problem in lower dimensions (e.g. point- location [31, 30

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

    Microsoft Academic Search

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

    2006-01-01

    Due to the surface smoothness of micromachined structures, strong adhesion forces between these fabricated structures and the substrate can be developed. The major adhesion mechanisms include capillary forces, hydrogen bonding, electrostatic forces and van der Waals forces. Once contact is made, the magnitude of these forces is in some cases sufficient to deform and pin these structures to the substrate,

  5. Optimal Attitude Control of a Rigid Body Using Geometrically Exact Computations on SO(3)

    Microsoft Academic Search

    Taeyoung Lee; Melvin Leok; N. Harris McClamroch

    2008-01-01

    An efficient and accurate computational approach is proposed for a nonconvex optimal attitude control for a rigid body. The\\u000a problem is formulated directly as a discrete time optimization problem using a Lie group variational integrator. Discrete\\u000a time necessary conditions for optimality are derived, and an efficient computational approach is proposed to solve the resulting\\u000a two-point boundary-value problem. This formulation wherein

  6. Design concept for wire-bonding reliability improvement by optimizing position in power devices

    Microsoft Academic Search

    Masayasu Ishiko; Masanori Usui; Takashi Ohuchi; Mikio Shirai

    2006-01-01

    The most effective way to increase the reliability of wire bonds in IGBT modules is reduction of temperature difference between the aluminum wires and the device. However, this lowers the power handling capability of the modules. In this paper, we show that the configuration of aluminum wire bonds on power devices has a considerable effect on the temperature distribution of

  7. DifferentialGeometric Methods: a Powerful Set of New Tools for Optimal Control

    E-print Network

    Sussmann, Hector

    in Section 2 below. 2 The distinctive feature of the work using DGM's in control theory is the adoption's are applied in control theory in three major ways: 1. To get new insights into classical problems of optimal control theory, such as local and global controllability, and the structure and properties of optimal tra

  8. A NEAR-OPTIMAL MULTIUSER DETECTOR FOR MC-CDMA SYSTEMS USING GEOMETRICAL APPROACH

    E-print Network

    Boyer, Edmond

    three characteristics very attractive for pratical systems. Firstly, it has nearly optimal perfor- mance, the algorithm has an inherent parallelism. To our knowledge, the HIS algorithm is not just an add). For a BER as low as 10-4 , the HIS algorithm introduces only 0.2 dB degradation compared to the optimal

  9. The packing of soft materials: Molecular asymmetry, geometric frustration and optimal lattices in block copolymer melts

    NASA Astrophysics Data System (ADS)

    Grason, Gregory M.

    Melts of block copolymers provide an ideal route to engineering well-controlled structures on nanometer length scales. Through the control of only a few thermodynamic parameters, these systems can be tuned to self-assemble into periodic structures of an astounding variety. It is known that geometry plays a particularly important role in determining equilibrium structure since phase behavior of copolymer melts is generically insensitive to detail at the monomeric scale. Here, we explore a particular way in which the geometry of packing objects in three dimensions frustrates the internal configurations of segregated block copolymer domains. In particular, we find that lattices of spherical micelles are sensitive to the periodic structure of the lattice arrangement because these micelles are forced to occupy the non-ideal, polyhedral unit cells of the lattice. By analyzing the energetics of block copolymer melts in the limit of strongly-segregated domains, we find that the interfaces which separate unlike polymer domains tend to adopt the polyhedral shape of the lattice unit cell, and this tendency is entirely controlled by the specific copolymer architecture. Furthermore, in the limit where interfaces are perfectly polyhedral, a remarkable simplicity emerges, and the relative stability of competing lattice arrangements of micelles can be assessed purely in terms of geometric measures of the two-dimensional lattice unit cell. From this analysis we predict the stability of a novel cubic arrangement spherical micelles in block copolymer melts, the A15 lattice. To corroborate our geometric arguments we develop and implement a numerical self-consistent field theory for melts of highly asymmetric block copolymers. This field theory allows us to systematically and efficiently explore the equilibrium phase behavior of asymmetric copolymer melts as a function of molecular architecture. These numerical results bear out the predictions of our geometric analysis and confirm that the A15 lattice arrangement of spherical micelles is stable in phase diagrams of asymmetric block copolymer melts.

  10. Optimizing dentin bond durability: control of collagen degradation by matrix metalloproteinases and cysteine cathepsins

    PubMed Central

    Tjäderhane, Leo; Nascimento, Fabio D.; Breschi, Lorenzo; Mazzoni, Annalisa; Tersariol, Ivarne L.S.; Geraldeli, Saulo; Tezvergil-Mutluay, Arzu; Carrilho, Marcela R.; Carvalho, Ricardo M.; Tay, Franklin R.; Pashley, David H.

    2012-01-01

    Objectives Contemporary adhesives lose their bond strength to dentin regardless of the bonding system used. This loss relates to the hydrolysis of collagen matrix of the hybrid layers. The preservation of the collagen matrix integrity is a key issue in the attempts to improve the dentin bonding durability. Methods Dentin contains collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, which are responsible for the hydrolytic degradation of collagen matrix in the bonded interface. Results The identities, roles and function of collagenolytic enzymes in mineralized dentin has been gathered only within last 15 years, but they have already been demonstrated to have an important role in dental hard tissue pathologies, including the degradation of the hybrid layer. Identifying responsible enzymes facilitates the development of new, more efficient methods to improve the stability of dentin-adhesive bond and durability of bond strength. Significance Understanding the nature and role of proteolytic degradation of dentin-adhesive interfaces has improved immensely and has practically grown to a scientific field of its own within only 10 years, holding excellent promise that stable resin-dentin bonds will be routinely available in a daily clinical setting already in a near future. PMID:22901826

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

    PubMed

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

    2011-06-01

    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

  12. 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

    J. Sussmann; Guoqing Tang

    1991-01-01

    We illustrate the use of the techniques of modern geometric optimal control theory by studying the shortest paths for a model of a car that can move forwards and backwards. This problem was discussed in recent work by Reeds and Shepp who showed, by special methods, (a) that shortest path motion could always be achieved by means of trajectories of

  13. Are geometrical and structural variations along the length of the aorta governed by a principle of "optimal mechanical operation"?

    PubMed

    Rachev, Alexander; Greenwald, Stephen; Shazly, Tarek

    2013-08-01

    It is well-documented that the geometrical dimensions, the longitudinal stretch ratio in situ, certain structural mechanical descriptors such as compliance and pressure-diameter moduli, as well as the mass fractions of structural constituents, vary along the length of the descending aorta. The origins of and possible interrelations among these observed variations remain open questions. The central premise of this study is that having considered the variation of the deformed inner diameter, axial stretch ratio, and area compliance along the aorta to be governed by the systemic requirements for flow distribution and reduction of cardiac preload, the zero-stress state geometry and mass fractions of the basic structural constituents of aortic tissue meet a principle of optimal mechanical operation. The principle manifests as a uniform distribution of the circumferential stress in the aortic wall that ensures effective bearing of the physiological load and a favorable mechanical environment for mechanosensitive vascular smooth muscle cells. A mathematical model is proposed and inverse boundary value problems are solved for the equations that follow from finite elasticity, structure-based constitutive modeling within constrained mixture theory, and stress-induced control of aortic homeostasis, mediated by the synthetic activity of vascular smooth muscle cells. Published experimental data are used to illustrate the predictive power of the proposed model. The results obtained are in agreement with published experimental data and support the proposed principle of optimal mechanical operation for the descending aorta. PMID:23722287

  14. Discrete-Time Pricing and Optimal Exercise of American Perpetual Warrants in the Geometric Random Walk Model

    SciTech Connect

    Vanderbei, Robert J., E-mail: rvdb@princeton.edu [Princeton University, Department of Operations Research and Financial Engineering (United States); P Latin-Small-Letter-Dotless-I nar, Mustafa C., E-mail: mustafap@bilkent.edu.tr [Bilkent University, Department of Industrial Engineering (Turkey); Bozkaya, Efe B. [Sabanc Latin-Small-Letter-Dotless-I University, Faculty of Administrative Sciences (Turkey)] [Sabanc Latin-Small-Letter-Dotless-I University, Faculty of Administrative Sciences (Turkey)

    2013-02-15

    An American option (or, warrant) is the right, but not the obligation, to purchase or sell an underlying equity at any time up to a predetermined expiration date for a predetermined amount. A perpetual American option differs from a plain American option in that it does not expire. In this study, we solve the optimal stopping problem of a perpetual American option (both call and put) in discrete time using linear programming duality. Under the assumption that the underlying stock price follows a discrete time and discrete state Markov process, namely a geometric random walk, we formulate the pricing problem as an infinite dimensional linear programming (LP) problem using the excessive-majorant property of the value function. This formulation allows us to solve complementary slackness conditions in closed-form, revealing an optimal stopping strategy which highlights the set of stock-prices where the option should be exercised. The analysis for the call option reveals that such a critical value exists only in some cases, depending on a combination of state-transition probabilities and the economic discount factor (i.e., the prevailing interest rate) whereas it ceases to be an issue for the put.

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

    PubMed Central

    Tjäderhane, Leo; Nascimento, Fabio D.; Breschi, Lorenzo; Mazzoni, Annalisa; Tersariol, Ivarne L.S.; Geraldeli, Saulo; Tezvergil-Mutluay, Arzu; Carrilho, Marcela; Carvalho, Ricardo M.; Tay, Franklin R.; Pashley, David H.

    2014-01-01

    Objectives Endogenous dentin collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, are responsible for the time-related hydrolysis of collagen matrix of the hybrid layers. As the integrity of the collagen matrix is essential for the preservation of long-term dentin bond strength, inhibition or inactivation of endogenous dentin proteases is necessary for durable resin-bonded composite resin restorations. Methods Dentin contains collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, which are responsible for the hydrolytic degradation of collagen matrix in the bonded interface. Several tentative approaches to prevent enzyme function either directly or indirectly have been proposed in the literature. Results Chlorhexidine, a general inhibitor of both MMPs and cysteine cathepsins, applied before primer/adhesive application is the most tested method. In general, these experiments have shown that enzyme inhibition is a promising scheme to improve hybrid layer preservation and bond strength durability. Other enzyme inhibitors, e.g. enzyme-inhibiting monomers and antimicrobial compounds, may be considered promising alternatives that would allow more simple clinical application than chlorhexidine. Cross-linking collagen and/or dentin organic matrix-bound enzymes could render hybrid layer organic matrix resistant to degradation, and complete removal of water from the hybrid layer with ethanol wet bonding or biomimetic remineralization should eliminate hydrolysis of both collagen and resin components. Significance Identification of the enzymes responsible for the hydrolysis of hybrid layer collagen and understanding their function has prompted several innovative approaches to retain the hybrid layer integrity and strong dentin bonding. The ultimate goal, prevention of collagen matrix degradation with techniques and commercially available materials that are simple and effective in clinical settings may be achievable in several ways, and will likely become reality in the near future. PMID:23953737

  16. A geometric approach to the optimal control of nonholnomic mechanical systems

    E-print Network

    Anthony Bloch; Leonardo Colombo; Rohit Gupta; David Martin de Diego

    2014-12-23

    In this paper, we describe a constrained Lagrangian and Hamiltonian formalism for the optimal control of nonholonomic mechanical systems. In particular, we aim to minimize a cost functional, given initial and final conditions where the controlled dynamics is given by nonholonomic mechanical system. In our paper, the controlled equations are derived using a basis of vector fields adapted to the nonholonomic distribution and the Riemannian metric determined by the kinetic energy. Given a cost function, the optimal control problem is understood as a constrained problem or equivalently, under some mild regularity conditions, as a Hamiltonian problem on the cotangent bundle of the nonholonomic distribution. A suitable Lagrangian submanifold is also shown to lead to the correct dynamics. We demonstrate our techniques in several examples including a continuously variable transmission problem and motion planning for obstacle avoidance problems.

  17. An inverse display color characterization model based on an optimized geometrical structure

    NASA Astrophysics Data System (ADS)

    Thomas, Jean-Baptiste; Colantoni, Philippe; Hardeberg, Jon Y.; Foucherot, Irène; Gouton, Pierre

    2008-01-01

    We have defined an inverse model for colorimetric characterization of additive displays. It is based on an optimized three-dimensional tetrahedral structure. In order to minimize the number of measurements, the structure is defined using a forward characterization model. Defining a regular grid in the device-dependent destination color space leads to heterogeneous interpolation errors in the device-independent source color space. The parameters of the function used to define the grid are optimized using a globalized Nelder-Mead simplex downhill algorithm. Several cost functions are tested on several devices. We have performed experiments with a forward model which assumes variation in chromaticities (PLVC), based on one-dimensional interpolations for each primary ramp along X, Y and Z (3×3×1-D). Results on 4 devices (2 LCD and a DLP projection devices, one LCD monitor) are shown and discussed.

  18. Geometric optimization of nozzles for inclined injectors for DI diesel engines

    SciTech Connect

    Chen, Y.; Kittelson, D.B. [Univ. of Minnesota, Minneapolis, MN (United States)

    1996-09-01

    Low emission heavy-duty diesel engines are increasingly utilizing four-valve designs with vertical central injectors. However, two-valve DI diesel engines with inclined injectors offset from the centerline of the piston bowl are likely to continue to be used in medium and light duty applications for some time. In such situations, designing of the hole-type nozzle is very difficult and may cause unavoidable back-drilling problems. The purpose of this paper is to solve back-drilling problems connected with hole-type nozzles and improve fuel-air mixing which leads to more efficient combustion. Based on geometric considerations, this paper introduces single-cone hole-type nozzles, double-cone hole-type nozzles, and the critical principal angles for hole-type nozzles. The single-cone hole-type nozzles and double-cone hole-type nozzles can meet requirements for height of the spray impingement points and spray orifice distribution angle at the same time. The concept of the critical principal angle for hole-type nozzles provides a criterion for the determination of both the hole-type nozzle angles and the injector installation angle. This paper also gives an example to illustrate the application of the above methods. Finally, this paper systematically summarizes design methods for hole-type nozzles that fit the DI combustion chamber.

  19. Optimal geometrical conditions of photoacoustic signal detection with a cylindrical direct coupling cell for liquids

    NASA Astrophysics Data System (ADS)

    Kitamori, Takehiko; Fujii, Masaaki; Sawada, Tsuguo; Gohshi, Yohichi

    1985-07-01

    The general description of photoacoustic (PA) signal generation in liquids developed in our earlier paper [J. Appl. Phys. 55, 4005 (1984)] was extended to analyze PA signal detection. The dependence of detected PA signal magnitude on the excitation beam profile and cell geometry of the cylindrical direct coupling cell was obtained theoretically. The thermal lens effect was clarified to be one of the dominant factors for determination of an acoustic source profile in liquids. These theoretical results were confirmed experimentally. Theoretical, optimized detection conditions for a highly sensitive cell (under a near-field condition) and a wide dynamic range cell (under a far-field condition) were proposed.

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

    PubMed

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

    2013-11-01

    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

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

    PubMed

    Kokiopoulou, Effrosyni; Kressner, Daniel; Frossard, Pascal

    2011-06-01

    This paper addresses the problem of image alignment based on random measurements. Image alignment consists of estimating the relative transformation between a query image and a reference image. We consider the specific problem where the query image is provided in compressed form in terms of linear measurements captured by a vision sensor. We cast the alignment problem as a manifold distance minimization problem in the linear subspace defined by the measurements. The transformation manifold that represents synthesis of shift, rotation, and isotropic scaling of the reference image can be given in closed form when the reference pattern is sparsely represented over a parametric dictionary. We show that the objective function can then be decomposed as the difference of two convex functions (DC) in the particular case where the dictionary is built on Gaussian functions. Thus, the optimization problem becomes a DC program, which in turn can be solved globally by a cutting plane method. The quality of the solution is typically affected by the number of random measurements and the condition number of the manifold that describes the transformations of the reference image. We show that the curvature, which is closely related to the condition number, remains bounded in our image alignment problem, which means that the relative transformation between two images can be determined optimally in a reduced subspace. PMID:21189239

  2. The packing of soft materials: Molecular asymmetry, geometric frustration and optimal lattices in block copolymer melts

    NASA Astrophysics Data System (ADS)

    Grason, Gregory M.

    2006-10-01

    Block copolymer systems are well known for their ability to self-assemble into a wide array of periodic structures. Due to the abundance and adaptability of physical theories describing polymers, this system is ideal for the development of robust and testible predictions about amphiphilic self-assembly phenomena at large. We review the results of field-theoretic treatments of block copolymer melts, with the aim of understanding how self-assembly in this system can be understood in terms of optimal lattice geometry. The self-consistent (mean) field theory of block copolymer melts as well as its low temperature limit, strong-segregation theory, are presented in detail, highlighting the special role played by asymmetry in the copolymer architecture. Special attention is paid to micellar configurations, where a well-defined and simple notion of optimal lattice geometry emerges from a particular asymptotic limit of the full self-consistent field theory. In this limit, the stability of competing arrangements of copolymer micelles can be assessed in terms of two discrete measures of the lattice geometry, emphasizing the non-trivial coupling between the internal configurations of the fundamentally soft micelles and the periodic symmetry of the lattice.

  3. Spatiotemporal and geometric optimization of sensor arrays for detecting analytes fluids

    DOEpatents

    Lewis, Nathan S.; Freund, Michael S.; Briglin, Shawn M.; Tokumaru, Phil; Martin, Charles R.; Mitchell, David T.

    2006-10-17

    Sensor arrays and sensor array systems for detecting analytes in fluids. Sensors configured to generate a response upon introduction of a fluid containing one or more analytes can be located on one or more surfaces relative to one or more fluid channels in an array. Fluid channels can take the form of pores or holes in a substrate material. Fluid channels can be formed between one or more substrate plates. Sensor can be fabricated with substantially optimized sensor volumes to generate a response having a substantially maximized signal to noise ratio upon introduction of a fluid containing one or more target analytes. Methods of fabricating and using such sensor arrays and systems are also disclosed.

  4. Soft Chelating Irrigation Protocol Optimizes Bonding Quality of Resilon\\/Epiphany Root Fillings

    Microsoft Academic Search

    Gustavo De-Deus; Fátima Namen; João Galan; Matthias Zehnder

    2008-01-01

    This study was designed to test the impact of either a strong (MTAD) or a soft (1-hydroxyethylidene-1, 1-bisphosphonate [HEPB]) chelating solution on the bond strength of Resilon\\/Epiphany root fillings. Both 17% EDTA and the omission of a chelator in the irrigation protocol were used as reference treatments. Forty extracted human upper lateral incisors were prepared using different irrigation protocols (n

  5. Estimation of Gravity Parameters Related to Simple Geometrical Structures by Developing an Approach Based on Deconvolution and Linear Optimization Techniques

    NASA Astrophysics Data System (ADS)

    Asfahani, J.; Tlas, M.

    2015-03-01

    An easy and practical method for interpreting residual gravity anomalies due to simple geometrically shaped models such as cylinders and spheres has been proposed in this paper. This proposed method is based on both the deconvolution technique and the simplex algorithm for linear optimization to most effectively estimate the model parameters, e.g., the depth from the surface to the center of a buried structure (sphere or horizontal cylinder) or the depth from the surface to the top of a buried object (vertical cylinder), and the amplitude coefficient from the residual gravity anomaly profile. The method was tested on synthetic data sets corrupted by different white Gaussian random noise levels to demonstrate the capability and reliability of the method. The results acquired show that the estimated parameter values derived by this proposed method are close to the assumed true parameter values. The validity of this method is also demonstrated using real field residual gravity anomalies from Cuba and Sweden. Comparable and acceptable agreement is shown between the results derived by this method and those derived from real field data.

  6. Evaluation of wire bonding performance, process conditions, and metallurgical integrity of chip on board wire bonds

    Microsoft Academic Search

    Daniel T. Rooney; Deepak Nager; David Geiger; Dongkai Shanguan

    2005-01-01

    Chip on board wire bonding presents challenges to modern wire bonding technology which include smaller, closely spaced wire bond pads; bonding to soft substrates without special processing and pad construction; and diverse first bond and second bond metallurgies. These challenges are addressed by extensive bonding accuracy tests, a design of experiments approach for optimizing wire bond process parameters, reliability testing,

  7. A study on optimal bonding angles of bi-material interfaces in dental crowns with porcelain fused to metal.

    PubMed

    Chowdhuri, M A K; Xia, Z; Yu, D

    2011-07-01

    Interfaces between two different materials exist in the dental crowns used in dental restoration work. A common failure mode observed in dental crowns is debonding/fracture that is initiated at the corners of the interface between two materials, where a stress concentration or a stress singularity can be created. In this paper, finite element modelling and analytical methods are used to analyse the stress singularity at the free edge corners at the interfaces between porcelain and metal and also metal and cement in porcelain-fused-to-metal (PFM) crowns. Optimal ranges of bonding angles at the corners of the interface, that result in the elimination of the stress singularity, are obtained for PFM crowns made from a precious-metal-based or non-precious-metal-based alloy, respectively. The findings presented in this paper can serve as guidelines for the design and manufacture of PFM dental crowns. PMID:21870373

  8. Ultrashort pulsed laser conditioning of human enamel: in vitro study of the influence of geometrical processing parameters on shear bond strength of orthodontic brackets.

    PubMed

    Lorenzo, M C; Portillo, M; Moreno, P; Montero, J; García, A; Santos-del Riego, S E; Albaladejo, A

    2015-02-01

    The surfaces of 63 extracted premolar teeth were processed with intense ultrashort laser pulses (??=?795 nm; pulse duration, 120 fs; repetition rate, 1 kHz) to produce cross patterns with different pitches (s) in the micrometer range in order to evaluate the influence of such microstructures on the shear bond strengths of orthodontic brackets to enamel. The samples were classified in nine groups corresponding to the control group (raw samples) and eight different laser-processed groups (cross patterns with s increasing from 15 to 180 ?m). Brackets were luted with Transbond(TM) XT adhesive resin to all the samples; after 72 h, they all were submitted to strength test in a universal testing machine. Additionally, a third of the samples underwent morphological analysis of the debonded surface by means of scanning electron microscope microscopy and an analysis of the failure mode based on the adhesive remnant index. The results showed that enamel microstructuring with ultrashort laser pulses remarkably increase the bond strength of brackets. Dense cross patterns (s?bond strengths as compared to control group whereas light ones (s?>?90 ?m) give rise to smaller improvements of the bond strength. A strong correlation of this behavior with the predominant failure mode in both scenarios was found. So far, the best compromise between suitable adhesive efficiency, processing time minimization, and enamel surface preservation suggests the performance of cross patterns with pitches in the order of 90 ?m. PMID:24249356

  9. Calculation of intramolecular hydrogen bonding strength and natural bond orbital (NBO) analysis of naphthazarin with chlorine substitution

    Microsoft Academic Search

    M. Zahedi-Tabrizi; R. Farahati

    2011-01-01

    The hydrogen bond strength, geometry optimization and 1H NMR for naphthazarin (NZ) and its chlorine substitutions have been calculated at the B3LYP\\/6-31G** theoretical level.The calculated chemical shifts of the chelated proton for all molecules, using GIAO method, are well correlate with the calculated geometrical parameters results.According to the calculated results, substitutions near the hydroxyl groups and near the carbonyl groups

  10. 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

    Park, Ga Young; Qayyum, Munzarin F.; Woertink, Julia; Hodgson, Keith O.; Hedman, Britt; Narducci Sarjeant, Amy A.; Solomon, Edward I.; Karlin, Kenneth D.

    2012-01-01

    Certain side-on peroxo dicopper(II) species with particularly low ?O–O (710–730 cm?1) have been found in equilibrium with their bis-?-oxo dicopper(III) isomer. An issue is whether such side-on peroxo bridges are further activated for O–O cleavage. In a previous study (Liang, H.-C., et al., J. Am. Chem. Soc. 2002, 124, 4170–4171), we showed that oxygenation of the three-coordinate complex [CuI(MeAN)]+ (MeAN=N-methyl-N,N-bis[3-(dimethylamino)propyl]amine) leads to a low-temperature stable [{CuII(MeAN)}2(?-?2:?2-O22?)]2+ peroxo species with low ?O–O (721 cm?1), as characterized by UV-Vis absorption and resonance Raman (rR) spectroscopies. Here, this complex has been crystallized as its SbF6? salt and an X-ray structure indicates the presence of an unusually long O–O bond (1.540(5) Å) consistent with the low ?O–O. EXAFS and rR spectroscopic and reactivity studies indicate the exclusive formation of [{CuII(MeAN)}2(?-?2:?2-O22?)]2+ without any bis-?-oxo-dicopper(III) isomer present. This is the first structure of a side-on peroxo dicopper(II) species with a significantly long and weak O–O bond. DFT calculations show that the weak O–O bond results from strong ? donation from the MeAN ligand to Cu that is compensated by a decrease in the extent of peroxo to Cu charge transfer. Importantly, the weak O–O bond does not reflect an increase in backbonding into the ?* orbital of the peroxide. Thus, although the O–O bond is unusually weak, this structure is not further activated for reductive cleavage to form a reactive bis-?-oxo-dicopper(III) species. These results highlight the necessity of understanding electronic structure changes associated with spectral changes for correlations to reactivity. PMID:22571744

  11. Computational Geometric Mechanics, Control, and Estimation of Rigid Bodies

    Microsoft Academic Search

    Taeyoung Lee

    Geometric mechanics involves the application of geometric and symmetry techniques to the study of Lagrangian or Hamil- tonian mechanics. The goal of computational geometric mechanics is to construct computational algorithms which preserve the geometric properties of mechanical systems (1). My research is focused on developing computational geometric meth- ods for numerical integration, optimal control, and optimal attitude estimation of rigid

  12. A simple geometric algorithm to predict optimal starting gantry angles using equiangular-spaced beams for intensity modulated radiation therapy of prostate cancer

    SciTech Connect

    Potrebko, Peter S.; McCurdy, Boyd M. C.; Butler, James B.; El-Gubtan, Adel S.; Nugent, Zoann [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 (Canada) and Division of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Division of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada) and Department of Radiology, University of Manitoba, Winnipeg, Manitoba R3A 1R9 (Canada); Department of Radiation Oncology, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada) and Department of Radiology, University of Manitoba, Winnipeg, Manitoba R3A 1R9 (Canada); Department of Epidemiology, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada)

    2007-10-15

    A fast, geometric beam angle optimization (BAO) algorithm for clinical intensity-modulated radiation therapy (IMRT) was implemented on ten localized prostate cancer patients on the Radiation Therapy Oncology Group (RTOG) 0126 protocol. The BAO algorithm computed the beam intersection volume (BIV) within the rectum and bladder using five and seven equiangular-spaced beams as a function of starting gantry angle for comparison to the V 75 Gy and V 70 Gy. A mathematical theory was presented to explain the correlation of BIV with dose and dose-volume metrics. The class solution 'W' pattern in the rectal V 75 Gy and V 70 Gy as a function of starting gantry angle using five equiangular-spaced beams (with two separate minima centered near 20 deg. and 50 deg. ) was reproduced by the 5 BIV within the rectum. A strong correlation was found between the rectal 5 BIV and the rectal V 75 Gy and V 70 Gy as a function of starting gantry angle. The BAO algorithm predicted the location of the two dosimetric minima in rectal V 75 Gy and V 70 Gy (optimal starting gantry angles) to within 5 deg. . It was demonstrated that the BIV geometric variations for seven equiangular-spaced beams were too small to translate into a strong dosimetric effect in the rectal V 75 Gy and V 70 Gy. The relatively flat distribution with starting gantry angle of the bladder V 75 Gy and V 70 Gy was reproduced by the bladder five and seven BIV for each patient. A geometric BAO method based on BIV has the advantage over dosimetric BAO methods of simplicity and rapid computation time. This algorithm can be used as a standalone optimization method or act as a rapid calculation filter to reduce the search space for a dosimetric BAO method. Given the clinically infeasible computation times of many dosimetric beam orientation optimization algorithms, this robust geometric BIV algorithm has the potential to facilitate beam angle selection for prostate IMRT in clinical practice.

  13. Geometric neural computing.

    PubMed

    Bayro-Corrochano, E J

    2001-01-01

    This paper shows the analysis and design of feedforward neural networks using the coordinate-free system of Clifford or geometric algebra. It is shown that real-, complex-, and quaternion-valued neural networks are simply particular cases of the geometric algebra multidimensional neural networks and that some of them can also be generated using support multivector machines (SMVMs). Particularly, the generation of radial basis function for neurocomputing in geometric algebra is easier using the SMVM, which allows one to find automatically the optimal parameters. The use of support vector machines in the geometric algebra framework expands its sphere of applicability for multidimensional learning. Interesting examples of nonlinear problems show the effect of the use of an adequate Clifford geometric algebra which alleviate the training of neural networks and that of SMVMs. PMID:18249926

  14. Classical knapsack to geometric knapsack: A journey

    Microsoft Academic Search

    Priya Ranjan Sinha Mahapatra; Sinha Mahapatra

    2011-01-01

    Knapsack problems have been extensively studied in operations research for last few decades. We review the method of mapping classical knapsack problems into a new class of geometric knapsack problems. Then it is shown that a wide class of problems in geometric optimization and facility location can be represented as geometric knapsack problems. Index Terms— Knapsack problem, Geometric Knapsack prob-

  15. Natural bond orbital analysis, electronic structure, non-linear properties and vibrational spectral analysis of l-histidinium bromide monohydrate: A density functional theory

    Microsoft Academic Search

    D. Sajan; Lynnette Joseph; N. Vijayan; M. Karabacak

    2011-01-01

    The spectroscopic properties of the crystallized nonlinear optical molecule l-histidinium bromide monohydrate (abbreviated as l-HBr-mh) have been recorded and analyzed by FT-IR, FT-Raman and UV techniques. The equilibrium geometry, vibrational wavenumbers and the first order hyperpolarizability of the crystal were calculated with the help of density functional theory computations. The optimized geometric bond lengths and bond angles obtained by using

  16. Iterative optimization of tail breaking force of 1mil wire thermosonic ball bonding processes and the influence of plasma cleaning

    Microsoft Academic Search

    J. Lee; M. Mayer; Y. Zhou; S. J. Hong

    2007-01-01

    An online tail breaking force measurement method is developed with a proximity sensor between wire clamp and horn. The wire under the tensile load measures about 1.5cm extending from the bond location to the wire clamp. To increase the sensitivity, the bondhead speed is reduced to 2mm\\/s during breaking the tail bond. It takes roughly 10ms to break the tail

  17. Computational Optimization of a Thermoelectric IceMaker as a Function of the Geometric Parameters of a Peltier Module

    Microsoft Academic Search

    J. G. Vián; D. Astrain; A. Rodríguez; A. Martínez

    2010-01-01

    The objective of this paper is to optimize a thermoelectric ice-maker installed in a no-frost refrigerator, by means of a\\u000a computational model. This model provides the electric power consumption of the Peltier module and the ice production. The\\u000a Peltier module is the most important part of the thermoelectric ice-maker; therefore, it must be optimized in order to obtain\\u000a an efficient

  18. Parallel Geometric Multigrid

    Microsoft Academic Search

    Frank Hülsemann; Markus Kowarschik; Marcus Mohr; Ulrich Rüde

    Multigrid methods are among the fastest numerical algorithms for the solution of large sparse systems of linear equations. While these algorithms exhibit asymptotically optimal computational complexity, their efficient parallelisation is hampered by the poor computation-to-communication ratio on the coarse grids. Our contribution discusses parallelisation techniques for geometric multigrid methods. It covers both theoretical approaches as well as practical implementation issues

  19. 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.

  20. Geometric Solids

    NSDL National Science Digital Library

    2012-09-18

    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).

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The insect kinins are present in a wide variety of insects and function as potent diuretic peptides, though they are subject to rapid degradation by internal peptidases. Insect kinin analogs incorporating stereochemical variants of (2S,4S)-4-aminopyroglutamate (APy), a cis-peptide bond motif, demon...

  2. Supplement To: OHO Hydrogen Bond Geometries and NMR Chemical Shifts: From Equilibrium Structures to Geometric H\\/D Isotope Effects, with Applications for Water, Protonated Water, and Compressed Ice

    Microsoft Academic Search

    Hans-Heinrich Limbach; Peter M. Tolstoy; Natalia Pérez-Hernández; Jing Guo; Ilya G. Shenderovich; Gleb S. Denisov

    2009-01-01

    Hydrogen bond geometries and 1 H NMR chemical shifts of OHO hy- drogen-bonded systems have been analyzed using an improved valence bond order model. This model predicts that the heavy atom hydrogen bond coordinateq2?=?r1 + r2 is a function of the proton coordinate q1 = ½(r1 - r2), where r1 and r2 represent the OH and the HO distances. In

  3. Chemical Bonds

    NSDL National Science Digital Library

    The Concord Consortium

    2011-12-11

    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.

  4. Bond forces and pressure in diatomic liquids

    Microsoft Academic Search

    J. Gao; J. H. Weiner

    1990-01-01

    Quantum-mechanical considerations indicate that a reasonable classical model for a diatomic system is one in which bond lengths are constant. Two types of such models may be distinguished: rigid models in which the constant length is imposed from the outset as a geometric constraint and flexible models in which the bond is represented by a stiff spring whose force constant

  5. Geometric Shapes

    NSDL National Science Digital Library

    Mr. Hoskins

    2005-11-21

    We will be learning the names and properties (# of sides, vertices, parallel sides, etc.) of several different geometric shapes. By now, everybody should know how many sides a square has and be able to recognize a circle. But, do you know how many vertices a parallelogram has, or how many sides to a rhombus? After completing the following exercies, you should be able to answer those questions and many ...

  6. Geometric Algebra

    E-print Network

    Eric Chisolm

    2012-05-27

    This is an introduction to geometric algebra, an alternative to traditional vector algebra that expands on it in two ways: 1. In addition to scalars and vectors, it defines new objects representing subspaces of any dimension. 2. It defines a product that's strongly motivated by geometry and can be taken between any two objects. For example, the product of two vectors taken in a certain way represents their common plane. This system was invented by William Clifford and is more commonly known as Clifford algebra. It's actually older than the vector algebra that we use today (due to Gibbs) and includes it as a subset. Over the years, various parts of Clifford algebra have been reinvented independently by many people who found they needed it, often not realizing that all those parts belonged in one system. This suggests that Clifford had the right idea, and that geometric algebra, not the reduced version we use today, deserves to be the standard "vector algebra." My goal in these notes is to describe geometric algebra from that standpoint and illustrate its usefulness. The notes are work in progress; I'll keep adding new topics as I learn them myself.

  7. Labyrinth stepped seal geometric optimization 

    E-print Network

    Wernig, Marcus Daniel

    1995-01-01

    High-speed rotating machinery poses a challenging problem to designers and engineers. Interference between rotating and stationary elements can result in excessive wear, decreased machine performance, or machine failure. Labyrinth seals present a...

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

    NASA Technical Reports Server (NTRS)

    Baz, A.; Poh, S.

    1987-01-01

    The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is studied. A Modified Independent Modal Space Control (MIMSC) method is devised to select the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The presented method accounts for the effects that the piezoelectric actuators and the bonding layers have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the MIMSC method and to demonstrate the effect of the physical and geometrical properties of the bonding layer on the dynamic performance of the actively controlled beams. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.

  9. Bond stretching phonon softening and angle-resolved photoemission kinks in optimally doped Bi2Sr1:6La0:4Cu2O6+sigma superconductors

    SciTech Connect

    Graf, Jeff; d'Astuto, M.; Jozwiak, C.; Garcia, D.R.; Saini, N.L.; Krisch, M.; Ikeuchi, K.; Baron, A.Q.R.; Eisaki, H.; Lanzara, Alessandra

    2008-05-08

    We report the first measurement of the Cu-O bond stretching phonon dispersion in optimally doped Bi2Sr1.6La0.4Cu2O6+delta using inelastic x-ray scattering. We found a softening of this phonon at q=(0.25,0,0) from 76 to 60 meV, similar to the one reported in other cuprates. A comparison with angle-resolved photoemission data on the same sample revealed an excellent agreement in terms of energy and momentum between the angle-resolved photoemission nodal kink and the soft part of the bond stretching phonon. Indeed, we find that the momentum space where a 63+-5 meV kink is observed can be connected with a vector q=(xi,0,0) with xi>= 0.22, corresponding exactly to the soft part of the bond stretching phonon.

  10. Characteristics of hydrogen bond revealed from water clusters

    NASA Astrophysics Data System (ADS)

    Song, Yan; Chen, Hongshan; Zhang, Cairong; Zhang, Yan; Yin, Yuehong

    2014-09-01

    The hydrogen bond network is responsible for the exceptional physical and chemical properties of water, however, the description of hydrogen bond remains a challenge for the studies of condensed water. The investigation of structural and binding properties of water clusters provides a key for understanding the H-bonds in bulk water. In this paper, a new set of geometric parameters are defined to describe the extent of the overlap between the bonding orbital of the donor OH and the nonbonding orbital of the lone-pair of the acceptor molecule. This orbital overlap plays a dominant role for the strength of H-bonds. The dependences of the binding energy of the water dimer on these parameters are studied. The results show that these parameters properly describe the H-bond strength. The ring, book, cage and prism isomers of water hexamer form 6, 7, 8 and 9 H-bonds, and the strength of the bonding in these isomers changes markedly. The internally-solvated and the all-surface structures of (H2O) n for n = 17, 19 and 21 are nearly isoenergetic. The internally-solvated isomers form fewer but stronger H-bonds. The hydrogen bonding in the above clusters are investigated in detail. The geometric parameters can well describe the characters of the H-bonds, and they correlate well with the H-bond strength. For the structures forming stronger H-bonds, the H-bond lengths are shorter, the angle parameters are closer to the optimum values, and their rms deviations are smaller. The H-bonds emanating from DDAA and DDA molecules as H-donor are relatively weak. The vibrational spectra of (H2O) n ( n = 17, 19 and 21) are studied as well. The stretching vibration of the intramolecular OH bond is sensitive to its bonding environment. The H-bond strength judged from the geometric parameters is in good agreement with the bonding strength judged from the stretching frequencies.

  11. HBexplore - a new tool for identifying and analysing hydrogen bonding patterns in biological macromolecules

    Microsoft Academic Search

    Klaus Lindauer; Cezar Bendic; Jürgen Sühnel

    1996-01-01

    The program HBexplore is a new tool for identifying and analysing H-bonding patterns in biological macromolecules. It selects all potential H-bonds according to geometrical criteria. The H-bond table can then be subjected to further automatic or interactive analysis tools. These tools include the calculation of mean values and distributions of geometrical H-bond parameters for parts of a single structure, for

  12. An Orientation-dependent Hydrogen Bonding Potential Improves Prediction of Specificity and

    E-print Network

    Morozov, Alexandre V.

    An Orientation-dependent Hydrogen Bonding Potential Improves Prediction of Specificity of Washington Box 351560, Seattle WA 98195-1560, USA Hydrogen bonding is a key contributor to the specificity-dependent hydrogen bonding potential based on the geometric characteristics of hydrogen bonds in high

  13. Geometric PSO + GP = Particle Swarm Programming

    E-print Network

    Togelius, Julian

    Geometric PSO + GP = Particle Swarm Programming Julian Togelius IDSIA USI/SUPSI, Galleria 2, 6928 (PSO) that applies naturally to both continuous and combinatorial spaces. In this paper we apply GPSO Optimization (PSO) is a relatively recently devised population-based stochastic global optimization al- gorithm

  14. A tutorial on geometric programming

    Microsoft Academic Search

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

    2007-01-01

    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.

  15. Pi Bond Orders and Bond Lengths

    ERIC Educational Resources Information Center

    Herndon, William C.; Parkanyi, Cyril

    1976-01-01

    Discusses three methods of correlating bond orders and bond lengths in unsaturated hydrocarbons: the Pauling theory, the Huckel molecular orbital technique, and self-consistent-field techniques. (MLH)

  16. 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)

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

    1986-01-01

    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.

  17. Optimism

    PubMed Central

    Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.

    2010-01-01

    Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998

  18. Geometric Generalization of the Nelder-Mead Algorithm

    Microsoft Academic Search

    Alberto Moraglio; Colin G. Johnson

    2010-01-01

    \\u000a The Nelder-Mead Algorithm (NMA) is an almost half-century old method for numerical optimization, and it is a close relative\\u000a of Particle Swarm Optimization (PSO) and Differential Evolution (DE). Geometric Particle Swarm Optimization (GPSO) and Geometric\\u000a Differential Evolution (GDE) are recently introduced formal generalization of traditional PSO and DE that apply naturally\\u000a to both continuous and combinatorial spaces. In this paper,

  19. HIERARCHICAL GEOMETRIC APPROXIMATIONS

    E-print Network

    North Carolina at Chapel Hill, University of

    HIERARCHICAL GEOMETRIC APPROXIMATIONS TR-050 1994 Amitabh Varshney Department of Computer Science;HIERARCHICAL GEOMETRIC APPROXIMATIONS by Amitabh Varshney A Dissertation submitted to the faculty Advisor Reader Reader Reader #12;@1994 Amitabh Varshney ALL RIGHTS RESERVED #12;AMITABH VARSHNEY

  20. Hybrid Matrix Geometric Algebra

    Microsoft Academic Search

    Garret Sobczyk; Gordon Erlebacher

    2004-01-01

    \\u000a The structures of matrix algebra and geometric algebra are completely compatible and in many ways complimentary, each having\\u000a their own advantages and disadvantages. We present a detailed study of the hybrid 2 × 2 matrix geometric algebra M(2,IG) with elements in the 8 dimensional geometric algebra IG=IG\\u000a 3 of Euclidean space. The resulting hybrid structure, isomorphic to the geometric algebra

  1. The geometrization of biology

    Microsoft Academic Search

    N. Rashevsky

    1956-01-01

    The twentieth century has witnessed a geometrization of physics, that is, a reduction of the basic concepts of physics to\\u000a geometric concepts. The topological approach to biology, recently proposed and to some extent developed by the author, is\\u000a a small step in the direction of geometrization of biology, but is unable to achieve the main purpose of such a geometrization

  2. Comparison of insect kinin analogs with cis-peptide bond, type VI-turn motifs identifies optimal stereochemistry for interaction with a recombinant arthropod kinin receptor from the southern cattle tick Boophilus microplus.

    PubMed

    Taneja-Bageshwar, S; Strey, A; Kaczmarek, K; Zabrocki, J; Pietrantonio, P V; Nachman, R J

    2008-02-01

    The multifunctional 'insect kinins' share the evolutionarily conserved C-terminal pentapeptide motif Phe-X1-X2-Trp-Gly-NH2, where X1=His, Asn, Ser, or Tyr and X2=Ser, Pro, or Ala; and are associated with the regulation of diuresis in a variety of species of insects. We previously reported the functional expression of a southern cattle tick (Boophilus microplus) G protein-coupled receptor that is activated by insect kinins. Four different stereochemical variants of each of the 4-aminopyroglutamic acid (APy) and tetrazole moieties, mimics of a cis-peptide bond, type VI beta-turn in insect kinins were now evaluated on the expressed tick receptor using a calcium bioluminescence plate assay. This study represents the first investigation of the interaction of restricted-conformation analogs incorporating components that mimic specific conformations and/or peptide bond orientations in an expressed arthropod neuropeptide receptor. Analog Ac-RF[APy]WGa (2R,4S) was at least 10-fold more active than the other analogs, thus identifying the optimal stereochemistry for tick receptor interaction. The optimal stereochemistry for the tetrazole insect kinin analogs in the tick receptor assay was identified as (D,L). The APy is superior to the tetrazole as a scaffold for the design of mimetic insect kinin analogs. These biostable analogs provide new tools for arthropod endocrinologists and potential leads in the development of selective, environmentally friendly arthropod pest control agents capable of disrupting insect kinin regulated processes. PMID:18192082

  3. Bonded Lubricants

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Another spinoff to the food processing industry involves a dry lubricant developed by General Magnaplate Corp. of Linden, N.J. Used in such spacecraft as Apollo, Skylab and Viking, the lubricant is a coating bonded to metal surfaces providing permanent lubrication and corrosion resistance. The coating lengthens equipment life and permits machinery to be operated at greater speed, thus increasing productivity and reducing costs. Bonded lubricants are used in scores of commercia1 applications. They have proved particularly valuable to food processing firms because, while increasing production efficiency, they also help meet the stringent USDA sanitation codes for food-handling equipment. For example, a cookie manufacturer plagued production interruptions because sticky batter was clogging the cookie molds had the brass molds coated to solve the problem. Similarly, a pasta producer faced USDA action on a sanitation violation because dough was clinging to an automatic ravioli-forming machine; use of the anti-stick coating on the steel forming plates solved the dual problem of sanitation deficiency and production line downtime.

  4. ArithmeticGeometric Progression

    E-print Network

    Feret, Jérôme

    VMCAI'05 The Arithmetic­Geometric Progression Abstract Domain Jérôme Feret École Normale Supérieure; Overview 1. Introduction 2. Case study 3. Arithmetic­geometric progressions 4. Benchmarks 5. Conclusion­geometric progressions 4. Benchmarks 5. Conclusion Jérôme Feret, LIENS 13 January, 2005 #12; Arithmetic

  5. Deforming geometric transitions

    NASA Astrophysics Data System (ADS)

    Rossi, Michele

    2015-04-01

    After a quick review of the wild structure of the complex moduli space of Calabi-Yau 3-folds and the role of geometric transitions in this context (the Calabi-Yau web) the concept of deformation equivalence for geometric transitions is introduced to understand the arrows of the Gross-Reid Calabi-Yau web as deformation-equivalence classes of geometric transitions. Then the focus will be on some results and suitable examples to understand under which conditions it is possible to get simple geometric transitions, which are almost the only well-understood geometric transitions both in mathematics and in physics.

  6. Students' Perceptions of Parental Bonding Styles and Their Academic Burnout

    ERIC Educational Resources Information Center

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

    2012-01-01

    This study investigated how parental bonding style affects academic burnout in Korean adolescents. Participants were 447 middle school students, who completed the Parental Bonding Instrument and the Maslach Burnout Inventory-Student Survey. MANCOVA results confirmed that adolescents reporting the optimal bonding parental style, for both mother and…

  7. GEOMETRIC DESCRIPTION OF VAKONOMIC AND NONHOLONOMIC DYNAMICS. COMPARISON OF SOLUTIONS

    Microsoft Academic Search

    J. CORT; M. DE; LE ´ ON; D. MARTIN DE DIEGO; S. MARTINEZ

    We treat the vakonomic dynamics with general constraints within a new geometric framework, which can be useful in the study of optimal control problems. We compare our for- mulation with the one of Vershik andGershkovich in the case of linear constraints. We show how nonholonomic mechanics also admits a new geometrical description which allows us to develop an algorithm of

  8. Chemical Bonds II

    ERIC Educational Resources Information Center

    Sanderson, R. T.

    1972-01-01

    The continuation of a paper discussing chemical bonding from a bond energy viewpoint, with a number of examples of single and multiple bonds. (Part I appeared in volume 1 number 3, pages 16-23, February 1972.) (AL)

  9. Bonding with Grandparents

    MedlinePLUS

    ... Sports: Keeping Kids Safe Concussions: What to Know Bonding With Grandparents KidsHealth > Parents > School & Family Life > Family ... encouraging a close relationship can benefit everyone involved. Bonding Benefits Establishing a bond with grandparents can benefit ...

  10. Bonding with Your Baby

    MedlinePLUS

    ... the child's social and cognitive development. Why Is Bonding Important? Bonding is essential for a baby. Studies ... as biological parents and their children. Back Continue Bonding With Daddy Men these days spend more time ...

  11. Parallel geometric multigrid for global weather prediction

    Microsoft Academic Search

    Sean D. Buckeridge; Robert Scheichl

    2010-01-01

    The subject of this work is an optimal and scalable parallel geometric multigrid solver for elliptic problems on the sphere. The use of fast elliptic solvers is cr ucial to the forecasting and data assim- ilation tools used at the UK Met Offi ce, and the preconditioned Krylov subspace solvers currently used do not perform well for large problem sizes

  12. Geometric integrators for ODEs

    Microsoft Academic Search

    Robert I. McLachlan; G. Reinout W. Quispel

    2006-01-01

    Geometric integration is the numerical integration of a differential equation, while preserving one or more of its 'geometric' properties exactly, i.e. to within round-off error. Many of these geometric properties are of crucial importance in physical applications: preservation of energy, momentum, angular momentum, phase-space volume, symmetries, time-reversal symmetry, symplectic structure and dissipation are examples. In this paper we present a

  13. 29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...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 §...

  14. 29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...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 §...

  15. 29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...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 §...

  16. 29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...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 §...

  17. 29 CFR 2580.412-20 - Use of existing bonds, separate bonds and additional bonding.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...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 §...

  18. Amino-Functionalized Multiwalled Carbon Nanotubes Lead to Successful Ring-Opening Polymerization of Poly(?-caprolactone): Enhanced Interfacial Bonding and Optimized Mechanical Properties.

    PubMed

    Roumeli, Eleftheria; Papageorgiou, Dimitrios G; Tsanaktsis, Vasilios; Terzopoulou, Zoe; Chrissafis, Konstantinos; Avgeropoulos, Apostolos; Bikiaris, Dimitrios N

    2015-06-01

    In this work, the synthesis, structural characteristics, interfacial bonding, and mechanical properties of poly(?-caprolactone) (PCL) nanocomposites with small amounts (0.5, 1.0, and 2.5 wt %) of amino-functionalized multiwalled carbon nanotubes (f-MWCNTs) prepared by ring-opening polymerization (ROP) are reported. This method allows the creation of a covalent-bonding zone on the surface of nanotubes, which leads to efficient debundling and therefore satisfactory dispersion and effective load transfer in the nanocomposites. The high covalent grafting extent combined with the higher crystallinity provide the basis for a significant enhancement of the mechanical properties, which was detected in the composites with up to 1 wt % f-MWCNTs. Increasing filler concentration encourages intrinsic aggregation forces, which allow only minor grafting efficiency and poorer dispersion and hence inferior mechanical performance. f-MWCNTs also cause a significant improvement on the polymerization reaction of PCL. Indeed, the in situ polymerization kinetics studies reveal a significant decrease in the reaction temperature, by a factor of 30-40 °C, combined with accelerated the reaction kinetics during initiation and propagation and a drastically reduced effective activation energy. PMID:25950403

  19. Mutual influence between anion-? and pnicogen bond interactions: the enhancement of P?N and P?O interactions by an anion-? bond.

    PubMed

    Esrafili, Mehdi D; Mohammadian-Sabet, Fariba; Solimannejad, Mohammad

    2015-04-01

    In this work, the interplay between anion-? and pnicogen bond interactions is investigated by ab initio calculations. Cooperative effects are observed in the studied complexes in which anion-? and pnicogen bond interactions coexist. These effects are analyzed in detail in terms of the energetic, geometric, charge-transfer and electron density properties of the complexes. The cooperative energy ranges from -1.8 to -4.1kcalmol(-1). The effect of an anion-? bond on a pnicogen bond is more pronounced than that of a pnicogen bond on an anion-? bond. The enhancing mechanism is analyzed in views with the charge-transfer, electrostatic potential and electron density analysis. PMID:25698102

  20. Geometric Dimensioning Sentence Structure.

    ERIC Educational Resources Information Center

    McCuistion, Patrick J.

    1991-01-01

    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…

  1. Geometric Shapes in Architecture

    NSDL National Science Digital Library

    Fox, Lauretta J.

    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.

  2. Geometrization of Quantum Mechanics

    E-print Network

    J. F. Carinena; J. Clemente-Gallardo; G. Marmo

    2007-03-23

    We show that it is possible to represent various descriptions of Quantum Mechanics in geometrical terms. In particular we start with the space of observables and use the momentum map associated with the unitary group to provide an unified geometrical description for the different pictures of Quantum Mechanics. This construction provides an alternative to the usual GNS construction for pure states.

  3. A Survey of Geometric Algebra

    E-print Network

    Harrington, J. Patrick

    A Survey of Geometric Algebra and Geometric Calculus c Alan Macdonald Luther College, Decorah, IA is always available at my web page.) The principal argument for the adoption of geometric algebra and Geometric Algebra: http://faculty.luther.edu/~macdonal/laga/ Vector and Geometric Calculus: http

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

    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.

  5. Hierarchies of Geometric Entanglement

    E-print Network

    Blasone, M; De Siena, S; Illuminati, F

    2007-01-01

    We introduce and discuss a class of generalized geometric measures of entanglement. For pure quantum states of N elementary subsystems, these extended measures are defined as the distances from the sets of K-separable states (K = 2,...,N). In principle, the entire set of these geometric measures provides a complete quantification and a hierarchical ordering of the different bipartite and multipartite components of the global geometric entanglement, and allows to discriminate among the different contributions. The extended measures are applied in the study of entanglement for different classes of N-qubit pure states, including W, GHZ, and cluster states. In all these cases we introduce a general method for the computation of the different geometric entanglement com- ponents. The entire set of geometric measures establishes an ordering among the different types of bipartite and multipartite entanglement. In particular, it determines a consistent hierarchy between GHZ and W states, clarifying the original result...

  6. Bond valence at mixed occupancy sites. I. Regular polyhedra.

    PubMed

    Bosi, Ferdinando

    2014-10-01

    Bond valence sum calculations at mixed occupancy sites show the occurrence of systematic errors leading to apparent violations of the Valence Sum Rule (bond valence theory) in regular and unstrained bonding environments. The systematic deviation of the bond valence from the expected value is observed in the long-range structure, and is discussed from geometric and algebraic viewpoints. In the valence-length diagram, such a deviation arises from discrepancies between the intersection points of the long-range bond valences and the theoretical bond valences with the valence-length curves of involved cations. Three factors cause systematic errors in the bond valences: difference in atomic valences, bond valence parameters Ri (the length of a bond of unit valence) and bond valence parameters bi (the bond softness) between the involved cations over the same crystallographic site. One important consequence strictly related to the systematic errors is that they lead to erroneous bond strain values for mixed occupancy sites indicating underbonding or overbonding that actually does not exist. PMID:25274520

  7. 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.

  8. LET'S BOND! A Chemical Bonding Webquest

    NSDL National Science Digital Library

    Mrs. Hicken

    2009-04-08

    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 ...

  9. Geometric requirements for hydrocarbon catalytic sites on platinum surfaces.

    PubMed

    Gao, Jie; Zhao, Haibo; Yang, Xiaofang; Koel, Bruce E; Podkolzin, Simon G

    2014-04-01

    Vibrational spectroscopic measurements and density functional calculations were used to identify a preferential catalytic mechanism for the transformation of acetylene, HC-CH, to vinylidene, C-CH2, on surfaces of Pt-Sn ordered alloys. In this mechanism, two adjacent Pt atoms adsorb an acetylene molecule and a third neighboring Pt atom is required for stabilizing the reacting H atom during the transformation. Therefore, unlike a direct H shift along the C-C bond in organometallic compounds with a single transition-metal atom, this mechanism has a geometric site requirement of three adjacent Pt atoms in the form of a three-fold site. The same geometric site requirement is identified for preferential C-H bond cleavage of acetylene with the formation of adsorbed C-CH and H species. In the absence of three-fold Pt sites, the reaction mechanism changes, and reactions of H transfer and C-H bond cleavage are suppressed. PMID:24615763

  10. Unusual bond paths in organolithium compounds

    SciTech Connect

    Bachrach, S.M.; Ritchie, J.P.

    1986-01-01

    We have applied the topological method to a number of organolithium compounds. The wavefunctions were determined with GAUSSIAN-82 using 3-21G basis set and fully optimized geometries. Gradient paths were obtained using the RHODER package and critical points were located using EXTREME. These results indicate the unusual nature of organolithium compounds. The strange bond paths arise mainly from the ionic nature of the C-Li interaction. We suggest that the term ''bond path'' may best be suited for covalent bonds. 4 figs., 1 tab.

  11. Geometric simulation of flexible motion in proteins.

    PubMed

    Wells, Stephen A

    2014-01-01

    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

  12. Geometric characteristics and energy landscapes of halogen-water-hydrogen bridges at protein-ligand interfaces

    NASA Astrophysics Data System (ADS)

    Lu, Shao-Yong; Jiang, Yong-Jun; Zhou, Peng; Zou, Jian-Wei; Wu, Tian-Xing

    2010-01-01

    Halogen-water-hydrogen bridges (XWH bridges), in which one hydrogen bond (H-bond) in a traditional water-mediated H-bond bridge is replaced by a halogen bond (X-bond), is a novel mode of interaction for water in biological molecules. In this study, we investigate several protein-halogenated ligand complexes using a two-layer quantum mechanics/molecular mechanics (QM/MM) ONIOM method. Analysis of the geometric characteristics and energy behaviors of the complexes, together with the AIM results, indicate that XWH bridges are present in these systems. Furthermore, our investigations show that XWH bridges can have an important role in ligand recognition and binding.

  13. AJ Geometric Formulas Calculator

    NSDL National Science Digital Library

    Jimmy Raymond

    Solve various attributes of shapes and solids. Includes calculations for circle, parallelogram, rectangle, square, trapezoid, right circular cone, right circular cylinder, rectangular solid, and sphere geometric formulas. Geometry attributes include volume, area, perimeter, surface area, radius, length and circumference.

  14. Geometric ghosts and unitarity

    SciTech Connect

    Ne'eman, Y.

    1980-09-01

    A review is given of the geometrical identification of the renormalization ghosts and the resulting derivation of Unitarity equations (BRST) for various gauges: Yang-Mills, Kalb-Ramond, and Soft-Group-Manifold.

  15. Geometric intrinsic symmetries

    SciTech Connect

    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

    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.

  16. Geometric Algebras and Extensors

    NASA Astrophysics Data System (ADS)

    Fernández, V. V.; Moya, A. M.; Rodrigues, W. A.

    This is the first paper in a series (of four) designed to show how to use geometric algebras of multivectors and extensors to a novel presentation of some topics of differential geometry which are important for a deeper understanding of geometrical theories of the gravitational field. In this first paper we introduce the key algebraic tools for the development of our program, namely the euclidean geometrical algebra of multivectors Cl(V,G_{E}) and the theory of its deformations leading to metric geometric algebras Cl(V,G) and some special types of extensors. Those tools permit obtaining, the remarkable golden formula relating calculations in Cl(V,G) with easier ones in Cl(V,G_{E}) (e.g., a noticeable relation between the Hodge star operators associated to G and G_{E}). Several useful examples are worked in details fo the purpose of transmitting the "tricks of the trade".

  17. Geometric direct search algorithms for image registration.

    PubMed

    Lee, Seok; Choi, Minseok; Kim, Hyungmin; Park, Frank Chongwoo

    2007-09-01

    A widely used approach to image registration involves finding the general linear transformation that maximizes the mutual information between two images, with the transformation being rigid-body [i.e., belonging to SE(3)] or volume-preserving [i.e., belonging to SL(3)]. In this paper, we present coordinate-invariant, geometric versions of the Nelder-Mead optimization algorithm on the groups SL(3), SE(3), and their various subgroups, that are applicable to a wide class of image registration problems. Because the algorithms respect the geometric structure of the underlying groups, they are numerically more stable, and exhibit better convergence properties than existing local coordinate-based algorithms. Experimental results demonstrate the improved convergence properties of our geometric algorithms. PMID:17784595

  18. Channel Bonding Notes 03/25/2004 Channel Bonding Notes

    E-print Network

    Jain, Amit

    Channel Bonding Notes 03/25/2004 Channel Bonding Notes Luke Hindman Department of Computer Science by attempting to use the Linux kernel bonding driver (bonding.o) to implement channel bonding on the master node. However, each time I would bring up the bonded interface (bond0) I would loose communication

  19. Prospects for Geometric Complexity Theory Prospects for Geometric Complexity Theory

    E-print Network

    Bürgisser, Peter

    Prospects for Geometric Complexity Theory Prospects for Geometric Complexity Theory Peter B¨urgisser University of Paderborn 27th IEEE Conference on Computational Complexity Porto, June 28, 2012 #12;Prospects for Geometric Complexity Theory Two major problems Two major problems #12;Prospects for Geometric Complexity

  20. Realization of ultrafast and high-quality anodic bonding using a non-contact scanning electrode

    NASA Astrophysics Data System (ADS)

    Wu, Jim-Wei; Yang, Chii-Rong; Huang, Mao-Jung; Yang, Cheng-Hao; Huang, Che-Yi

    2013-07-01

    The anodic bonding technique, which is primarily used in glass to silicon wafer bonding, has been extensively used in microelectromechanical systems (MEMS) for the packaging of microsensors and microactuators. When the bonding voltage is applied, the bonded region instantly occurs at the contact point of the cathode with the glass. The geometric shape or arranged pattern of the cathode electrode significantly affects the bonding quality, particularly the gas-trapping at the bonded interface and the bonding time. This paper presents a novel anodic bonding process, in which the non-contacting and rotating electrode with radial lines is used as the cathode for scan bonding with arc-discharge assistance. The experimental results show that a bonding ratio of 99.98% and an average bonding strength of 15.45 MPa for a 4-inch silicon/glass bonded pair can be achieved in a 17 s bonding time by using a cathode electrode with eight 45 included-angle radial lines at a rotation speed of 0.45 rpm, a non-contact gap of 120 µm, a bonding voltage of 900 V and a bonding temperature of 400 °C. This ultrafast and high-quality anodic bonding has been synchronously realized under this scan bonding technique.

  1. Evidence for stereoelectronic effects in the N-C-N group of 8,10,12-triaza-1-azoniatetracyclo[8.3.1.1(8,12).0(2,7)]pentadecane 4-nitrophenolate 4-nitrophenol monosolvate from the protonation of aminal (2R,7R)-1,8,10,12-tetraazatetracyclo[8.3.1.1(8,12).0(2,7)]pentadecane: X-ray and natural bond orbital analysis.

    PubMed

    Rivera, Augusto; Uribe, Juan Manuel; Ríos-Motta, Jaime; Osorio, Hector Jairo; Bolte, Michael

    2015-04-01

    The title molecular salt, C11H21N4(+)·C6H4NO3(-)·C6H5NO3, (II), crystallizes with two independent three-component aggregates in the asymmetric unit. In the cations, the cyclohexane rings fused to the cage azaadamantane systems both adopt a chair conformation. In the crystal structure, the aggregates are connected by C-H···O hydrogen bonds, forming a supramolecular unit enclosing an R4(4)(24) ring motif. These units are linked via C-H···O and C-H···N hydrogen bonds, forming a three-dimensional network. Even hydrogen-bond formation to one of the N atoms is enough to induce structural stereoelectronic effects in the normal donor?acceptor direction. The C-N bond distances provide structural evidence for a strong anomeric effect. The structure also displays O-H···O and N-H···O hydrogen bonding. Geometric optimization and natural bond orbital (NBO) analysis of (II) were undertaken by utilizing DFT/B3LYP with the 6-31+G(d,p) basis set. NBO second-order perturbation theory calculations indicate donor-acceptor interactions between nitrogen lone pairs and the antibonding orbital of the C-C and C-N bonds for the protonated polyamine, in agreement with the occurrence of bond-length and bond-angle changes within the aminal cage structure. PMID:25836286

  2. Applications of Parametric Searching in Geometric Optimization

    Microsoft Academic Search

    Pankaj K. Agarwal; Micha Sharirz; Sivan Toledo

    We present several applications in computational geometry of Megiddo's parametric searching technique. These applications include: (1) Finding the minimum Hausdor distance under translation between two polygonal regions in the plane under the Euclidean metric; (2) Computing the biggest line segment that can be placed inside a simple polygon; (3) Computing the smallest width annulus that can contain a given set

  3. Optimization in Geometric Graphs: Complexity and Approximation

    E-print Network

    Kahruman-Anderoglu, Sera

    2011-02-22

    and Gonzalez [70] and the edge contraction heuristic. : : : : : : : : : : : : : : : : : : : 120 6 Comparative results of the ratios of the cut value to the graph?s total edge weight achieved by SG, C, CSG, SG1, SG2 and SG3. : : 121 ix LIST OF FIGURES FIGURE... scheme for node deletion problems based on heuristics. : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 102 24 The Edge Contraction Heuristic. : : : : : : : : : : : : : : : : : : : : 114 25 The SG1 Algorithm...

  4. Water Resource System Optimization by Geometric Programming 

    E-print Network

    Meier, W. L.; Shih, C. S.; Wray, D. J.

    1971-01-01

    have increased considerably. Secondly, planning and design analyses have become more complicated because of a desire by planners to represent more completely the problem to be solved. In a recent appraisal of Federal Water Resources Research activities...

  5. Objective Improvement in Information-Geometric Optimization

    E-print Network

    distributions the pure rank-µ CMA- ES update is recovered, and for exponential families in ex- pectation of covariance matrix adaptation evo- lution strategies (CMA-ES), the so-called pure rank-µ CMA- ES update [11

  6. Semionic resonating valence bond states

    E-print Network

    Mohsin Iqbal; Didier Poilblanc; Norbert Schuch

    2014-08-06

    The nature of the kagome Heisenberg antiferromagnet (HAFM) is under ongoing debate. While recent evidence points towards a Z_2 topological spin liquid, the exact nature of the topological phase is still unclear. In this paper, we introduce semionic Resonating Valence Bond (RVB) states, this is, Resonating Valence Bond states which are in the Z_2 ordered double-semion phase, and study them using Projected Entangled Pair States (PEPS). We investigate their physics and study their suitability as an ansatz for the HAFM, as compared to a conventional RVB state which is in the Toric Code Z_2 topological phase. In particular, we find that a suitably optimized "semionic simplex RVB" outperforms the equally optimized conventional "simplex RVB" state, and that the entanglement spectrum (ES) of the semionic RVB behaves very differently from the ES of the conventional RVB, which suggests to use the ES to discriminate the two phases. Finally, we also discuss the possible relevance of space group symmetry breaking in valence bond wavefunctions with double-semion topological order.

  7. Geometric Nelder-Mead Algorithm for the permutation representation

    Microsoft Academic Search

    Alberto Moraglio; Julian Togelius

    2010-01-01

    The Nelder-Mead Algorithm (NMA) is an almost half-century old method for numerical optimization, and it is a close relative of Particle Swarm Optimization (PSO) and Differential Evolution (DE). In recent work, PSO, DE and NMA have been generalized using a formal geometric framework that treats solution representations in a uniform way. These formal algorithms can be used as templates to

  8. Methods and apparatuses for signaling with geometric constellations

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  9. Essays on corporate bonds

    E-print Network

    Bao, Jack (Jack C.)

    2009-01-01

    This thesis consists of three empirical essays on corporate bonds, examining the role of both credit risk and liquidity. In the first chapter, I test the ability of structural models of default to price corporate bonds in ...

  10. Implicit learning of geometric eigenfaces.

    PubMed

    Gao, Xiaoqing; Wilson, Hugh R

    2014-06-01

    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

  11. Gaussian states and geometrically uniform symmetry

    E-print Network

    Gianfranco Cariolaro; Roberto Corvaja; Gianfranco Pierobon

    2014-10-20

    Quantum Gaussian states can be considered as the majority of the practical quantum states used in quantum communications and more generally in quantum information. Here we consider their properties in relation with the geometrically uniform symmetry, a property of quantum states that greatly simplifies the derivation of the optimal decision by means of the square root measurements. In a general framework of the $N$-mode Gaussian states we show the general properties of this symmetry and the application of the optimal quantum measurements. An application example is presented, to quantum communication systems employing pulse position modulation. We prove that the geometrically uniform symmetry can be applied to the general class of multimode Gaussian states.

  12. Diffusion bonding aeroengine components

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, G. A.; Broughton, T.

    1988-10-01

    The use of diffusion bonding processes at Rolls-Royce for the manufacture of titanium-alloy aircraft engine components and structures is described. A liquid-phase diffusion bonding process called activated diffusion bonding has been developed for the manufacture of the hollow titanium wide chord fan blade. In addition, solid-state diffusion bonding is being used in the manufacture of hollow vane/blade airfoil constructions mainly in conjunction with superplastic forming and hot forming techniques.

  13. Bonding silicones with epoxies

    SciTech Connect

    Tira, J.S.

    1980-01-01

    It is shown that silicones, both room temperature vulcanizing (RTV) and millable rubber (press cured) can be successfully bonded to other materials using plasma treatment and epoxy adhesives. The plasma treatment using dry air atmosphere increases the surface energy of the silicone and thus provides a lower water contact angle. This phenomenon allows the epoxy adhesive to wet the silicone surface and ultimately bond. Bond strengths are sufficiently high to result in failures in the silicone materials rather than the adhesive bond.

  14. Allosteric Disulfide Bonds

    Microsoft Academic Search

    Jason W. H. Wong; Philip J. Hogg

    \\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

  15. Making and Breaking Bonds

    NSDL National Science Digital Library

    The Concord Consortium

    2011-12-11

    Atoms collide and, under certain circumstances, react to form bonds with one another. The process of association is the bonding of atoms into a molecule while dissociation is the process by which a molecule breaks apart into simpler groups of atoms, individual atoms, or ions. Students interact with a molecular dynamics model to explore the making and breaking of bonds.

  16. Rapid adhesive bonding concepts

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

  17. Bonding thermoplastic polymers

    DOEpatents

    Wallow, Thomas I. (Fremont, CA); Hunter, Marion C. (Livermore, CA); Krafcik, Karen Lee (Livermore, CA); Morales, Alfredo M. (Livermore, CA); Simmons, Blake A. (San Francisco, CA); Domeier, Linda A. (Danville, CA)

    2008-06-24

    We demonstrate a new method for joining patterned thermoplastic parts into layered structures. The method takes advantage of case-II permeant diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. It is capable of producing bonds characterized by cohesive failure while preserving the fidelity of patterned features in the bonding surfaces. This approach is uniquely suited to production of microfluidic multilayer structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometer length scales. The bond enhancing procedure is easily integrated in standard process flows and requires no specialized equipment.

  18. Prospective bonding applications

    NASA Astrophysics Data System (ADS)

    Ancenay, H.; Benazet, D.

    1981-07-01

    Adhesive bonding in industry and in the laboratory is surveyed and prospects for its wider utilization are assessed. The economic impact of bonding technology on industry is discussed. Research is reviewed, centering on the development of nondestructive testing and inspection techniques. Traditional (wood) as well as new materials susceptible to bonding are considered. Applications in construction and civil engineering, in aeronautics, and in the automobile industry are covered. The use of glues in mechanical constructions, in assembling cylindrical parts, and in metal-metal bonding are examined. Hybrid assembling and bonding of composite materials are included.

  19. Development of Nickel Wire Bonding for High-Temperature Packaging of SiC Devices

    Microsoft Academic Search

    Ravi K. Burla; Li Chen; Christian A. Zorman; Mehran Mehregany

    2009-01-01

    This paper describes a detailed investigation of an ultrasonic nickel wire bonding technique for silicon carbide (SiC) devices, and its comparison with a thermosonic wire bonding process, for high-temperature applications. The study focuses on bonding 25-mum-diameter Ni wires to 750-nm-thick Ni pads deposited on 3C-SiC substrates. First, the Ni wire bonding recipe is optimized for maximum bond strength using a

  20. A reliable thermosonic wire bond of GaAs-devices analysed by infrared-microscopy

    Microsoft Academic Search

    S. Weiss; E. Zakel; H. Reichl

    1994-01-01

    Due to the delicate sensitiveness of GaAs devices, ultrasonic energy is generally regarded as a critical reliability parameter for wire bonding. Therefore wire bonding is usually performed using thermocompression. The subject of this work is a description of bond parameters for thermosonic wire bonding using 25 ?m Au-wire and a gold plated pad-metallization. The range of optimal bond parameters which

  1. Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    A methodology is presented for determining the fatigue life of bonded composite skin/stringer structures based on delamination fatigue characterization data and geometric nonlinear finite element analyses. Results were compared to fatigue tests on stringer flange/skin specimens to verify the approach.

  2. Coherent Control of Bond Making

    NASA Astrophysics Data System (ADS)

    Levin, Liat; Skomorowski, Wojciech; Rybak, Leonid; Kosloff, Ronnie; Koch, Christiane P.; Amitay, Zohar

    2015-06-01

    We demonstrate coherent control of bond making, a milestone on the way to coherent control of photoinduced bimolecular chemical reactions. In strong-field multiphoton femtosecond photoassociation experiments, we find the yield of detected magnesium dimer molecules to be enhanced for positively chirped pulses and suppressed for negatively chirped pulses. Our ab initio model shows that control is achieved by purification combined with chirp-dependent Raman transitions. Experimental closed-loop phase optimization using a learning algorithm yields an improved pulse that utilizes vibrational coherent dynamics in addition to chirp-dependent Raman transitions. Our results show that coherent control of binary photoreactions is feasible even under thermal conditions.

  3. Composite Planar Tolerance Allocation with Dimensional and Geometric Specifications

    Microsoft Academic Search

    Z. Li; Z. Xu; Y. Gao; M. Huang

    2002-01-01

    A new optimal approach for planar tolerance allocation is proposed in which dimensional and orientation geometric specifications\\u000a are included. To deal with the increased complexity of planar tolerance analysis, a special relevance graph (SRG) is used\\u000a to represent the relationships between manufactured elements and their size and tolerance information. In addition, the SRG\\u000a is also applied for the geometric dimensions

  4. Rapid bonding of Pyrex glass microchips.

    PubMed

    Akiyama, Yoshitake; Morishima, Keisuke; Kogi, Atsuna; Kikutani, Yoshikuni; Tokeshi, Manabu; Kitamori, Takehiko

    2007-03-01

    A newly developed vacuum hot press system has been specially designed for the thermal bonding of glass substrates in the fabrication process of Pyrex glass microchemical chips. This system includes a vacuum chamber equipped with a high-pressure piston cylinder and carbon plate heaters. A temperature of up to 900 degrees C and a force of as much as 9800 N could be applied to the substrates in a vacuum atmosphere. The Pyrex substrates bonded with this system under different temperatures, pressures, and heating times were evaluated by tensile strength tests, by measurements of thickness, and by observations of the cross-sectional shapes of the microchannels. The optimal bonding conditions of the Pyrex glass substrates were 570 degrees C for 10 min under 4.7 N/mm(2) of applied pressure. Whereas more than 16 h is required for thermal bonding with a conventional furnace, the new system could complete the whole bonding processes within just 79 min, including heating and cooling periods. Such improvements should considerably enhance the production rate of Pyrex glass microchemical chips. Whereas flat and dust-free surfaces are required for conventional thermal bonding, especially without long and repeated heating periods, our hot press system could press a fine dust into glass substrates so that even the areas around the dust were bonded. Using this capability, we were able to successfully integrate Pt/Ti thin film electrodes into a Pyrex glass microchip. PMID:17370301

  5. Generative geometric design

    Microsoft Academic Search

    L. Heisserman

    1994-01-01

    Boundary solid grammars use design rules that express complex geometric conditions and operations using a logical reasoning mechanism, allowing one to construct powerful rules and describe appropriate grammars for the generation of solid models for a variety of design domains. The formalism I present in this article is not sufficient for all engineering and architectural domains (e.g., polyhedral solids are

  6. Untangling Geometric Ideas

    ERIC Educational Resources Information Center

    Burgess, Claudia R.

    2014-01-01

    Designed for a broad audience, including educators, camp directors, afterschool coordinators, and preservice teachers, this investigation aims to help individuals experience mathematics in unconventional and exciting ways by engaging them in the physical activity of building geometric shapes using ropes. Through this engagement, the author…

  7. Geometric Algorithms primitive operations

    E-print Network

    Sedgewick, Robert

    algebra and check. · Idea 2: check if the endpoints of one line segment are on differe1 Geometric Algorithms primitive operations convex hull closest pair voronoi diagram References://www.ics.uci.edu/~eppstein/geom.html airflow around an aircraft wing #12;3 primitive operations convex hull closest pair voronoi diagram #12

  8. Geometric grid generation

    NASA Technical Reports Server (NTRS)

    Ives, David

    1995-01-01

    This paper presents a highly automated hexahedral grid generator based on extensive geometrical and solid modeling operations developed in response to a vision of a designer-driven one day turnaround CFD process which implies a designer-driven one hour grid generation process.

  9. Geometric Series via Probability

    ERIC Educational Resources Information Center

    Tesman, Barry

    2012-01-01

    Infinite series is a challenging topic in the undergraduate mathematics curriculum for many students. In fact, there is a vast literature in mathematics education research on convergence issues. One of the most important types of infinite series is the geometric series. Their beauty lies in the fact that they can be evaluated explicitly and that…

  10. Attributes of Geometric Shapes

    NSDL National Science Digital Library

    Michael Banek

    2012-06-18

    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.

  11. Pragmatic geometric model evaluation

    NASA Astrophysics Data System (ADS)

    Pamer, Robert

    2015-04-01

    Quantification of subsurface model reliability is mathematically and technically demanding as there are many different sources of uncertainty and some of the factors can be assessed merely in a subjective way. For many practical applications in industry or risk assessment (e. g. geothermal drilling) a quantitative estimation of possible geometric variations in depth unit is preferred over relative numbers because of cost calculations for different scenarios. The talk gives an overview of several factors that affect the geometry of structural subsurface models that are based upon typical geological survey organization (GSO) data like geological maps, borehole data and conceptually driven construction of subsurface elements (e. g. fault network). Within the context of the trans-European project "GeoMol" uncertainty analysis has to be very pragmatic also because of different data rights, data policies and modelling software between the project partners. In a case study a two-step evaluation methodology for geometric subsurface model uncertainty is being developed. In a first step several models of the same volume of interest have been calculated by omitting successively more and more input data types (seismic constraints, fault network, outcrop data). The positions of the various horizon surfaces are then compared. The procedure is equivalent to comparing data of various levels of detail and therefore structural complexity. This gives a measure of the structural significance of each data set in space and as a consequence areas of geometric complexity are identified. These areas are usually very data sensitive hence geometric variability in between individual data points in these areas is higher than in areas of low structural complexity. Instead of calculating a multitude of different models by varying some input data or parameters as it is done by Monte-Carlo-simulations, the aim of the second step of the evaluation procedure (which is part of the ongoing work) is to calculate basically two model variations that can be seen as geometric extremes of all available input data. This does not lead to a probability distribution for the spatial position of geometric elements but it defines zones of major (or minor resp.) geometric variations due to data uncertainty. Both model evaluations are then analyzed together to give ranges of possible model outcomes in metric units.

  12. The rotational spectrum and geometrical structure of thiozone, S3.

    PubMed

    McCarthy, Michael C; Thorwirth, Sven; Gottlieb, Carl A; Thaddeus, Patrick

    2004-04-01

    The rotational spectrum of thiozone, S3, has been observed for the first time. From the rotational constants of the normal and 34S isotopic species, a precise geometrical structure has been derived: S3 is a bent chain with a bond to the apex S of length 1.917(1) A and an apex angle of 117.36(6) degrees . The derived structural parameters indicate substantial double-bonding character in S3 and sp2 hybridization of the central sulfur atom. Thiozone is an excellent candidate for astronomical detection in the atmosphere of Io, the innermost Galilean moon of Jupiter, and in rich interstellar sources. PMID:15053585

  13. Effect of plasma treatment of Au-Ni-Cu bond pads on process windows of Au wire bonding

    Microsoft Academic Search

    Yu Hin Chan; Jang-Kyo Kim; Deming Liu; P. C. K. Liu; Yiu-Ming Cheung; Ming Wai Ng

    2005-01-01

    The wire bondability of Au-Ni-Cu bond pads with different Au plating schemes, including electrolytic and immersion plates, are evaluated after plasma treatment. The plasma cleaning conditions, such as cleaning power and time, are optimized based on the process window and wire pull strength measurements for different bond pad temperatures. Difference in the efficiency of plasma treatment in improving the wire

  14. Bonded semiconductor substrate

    DOEpatents

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

    2010-07-13

    Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600.degree. C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.

  15. Geometric diffusion of quantum trajectories

    PubMed Central

    Yang, Fan; Liu, Ren-Bao

    2015-01-01

    A quantum object can acquire a geometric phase (such as Berry phases and Aharonov–Bohm phases) when evolving along a path in a parameter space with non-trivial gauge structures. Inherent to quantum evolutions of wavepackets, quantum diffusion occurs along quantum trajectories. Here we show that quantum diffusion can also be geometric as characterized by the imaginary part of a geometric phase. The geometric quantum diffusion results from interference between different instantaneous eigenstate pathways which have different geometric phases during the adiabatic evolution. As a specific example, we study the quantum trajectories of optically excited electron-hole pairs in time-reversal symmetric insulators, driven by an elliptically polarized terahertz field. The imaginary geometric phase manifests itself as elliptical polarization in the terahertz sideband generation. The geometric quantum diffusion adds a new dimension to geometric phases and may have applications in many fields of physics, e.g., transport in topological insulators and novel electro-optical effects. PMID:26178745

  16. Quantum computation using geometric algebra

    NASA Astrophysics Data System (ADS)

    Matzke, Douglas James

    This dissertation reports that arbitrary Boolean logic equations and operators can be represented in geometric algebra as linear equations composed entirely of orthonormal vectors using only addition and multiplication Geometric algebra is a topologically based algebraic system that naturally incorporates the inner and anticommutative outer products into a real valued geometric product, yet does not rely on complex numbers or matrices. A series of custom tools was designed and built to simplify geometric algebra expressions into a standard sum of products form, and automate the anticommutative geometric product and operations. Using this infrastructure, quantum bits (qubits), quantum registers and EPR-bits (ebits) are expressed symmetrically as geometric algebra expressions. Many known quantum computing gates, measurement operators, and especially the Bell/magic operators are also expressed as geometric products. These results demonstrate that geometric algebra can naturally and faithfully represent the central concepts, objects, and operators necessary for quantum computing, and can facilitate the design and construction of quantum computing tools.

  17. Crystal-Like geometric modeling 

    E-print Network

    Landreneau, Eric Benjamin

    2006-08-16

    Crystals are natural phenomena that exhibit high degrees of order, symmetry, and recursion. They naturally form interesting and inspiring geometric shapes. This thesis provides geometric modeling techniques for creating shapes with crystallike...

  18. Geometric Mechanics of Periodic Pleated Origami

    E-print Network

    Wei, Zhiyan; Dudte, Levi; Liang, Haiyi; Mahadevan, L

    2012-01-01

    Origami is the archetype of a structural material with unusual mechanical properties that arise almost exclusively from the geometry of its constituent folds and forms the basis for mechanical metamaterials with an extreme deformation response. Here we consider a simple periodically folded structure Miura-ori, which is composed of identical unit cells of mountain and valley folds with four-coordinated ridges, de?fined completely by 2 angles and 2 lengths. We use the geometrical properties of a Miura-ori plate to characterize its elastic response to planar and non-planar piece- wise isometric deformations and calculate the two-dimensional stretching and bending response of a Miura-ori sheet, and show that the in-plane and out-of-plane Poisson's ratios are equal in magnitude, but opposite in sign. Our geometric approach also allows us to solve the inverse design problem of determining the geometric parameters that achieve the optimal geometric and mechanical response of such structures.

  19. Semiconductor Wafer Bonding

    Microsoft Academic Search

    U. Gosele; Q.-Y. Tong

    1998-01-01

    When mirror-polished, flat, and clean wafers of almost any material are brought into contact at room temperature, they are locally attracted to each other by van der Waals forces and adhere or bond. This phenomenon is referred to as wafer bonding. The most prominent applications of wafer bonding are silicon-on-insulator (SOI) devices, silicon-based sensors and actuators, as well as optical

  20. Energy pulse bonding

    NASA Technical Reports Server (NTRS)

    Smith, G. C.

    1972-01-01

    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.

  1. Chemical bonding technology

    NASA Technical Reports Server (NTRS)

    Plueddemann, E.

    1986-01-01

    Primers employed in bonding together the various material interfaces in a photovoltaic module are being developed. The approach develops interfacial adhesion by generating actual chemical bonds between the various materials bonded together. The current status of the program is described along with the progress toward developing two general purpose primers for ethylene vinyl acetate (EVA), one for glass and metals, and another for plastic films.

  2. One Bond Strategy

    NSDL National Science Digital Library

    2001-01-01

    Provided by SmartMoney.com (see the May 20, 1999 Scout Report for Business & Economics), this quick and easy yet thorough guide takes readers through the process of developing a bond portfolio. At the site, users will find help on deciding how much to invest in bonds, how to divide their portfolio, and tips on investing for both income and profit. First, however, visitors might want to wet their feet in the bond primer section, which covers all the basics, explains the yield curve, offers a calculator and glossary, and throws in "ten things your broker won't tell you about bonds" for good measure.

  3. Hydrogen bonding and anaesthesia

    NASA Astrophysics Data System (ADS)

    Sándorfy, C.

    2004-12-01

    General anaesthetics act by perturbing intermolecular associations without breaking or forming covalent bonds. These associations might be due to a variety of van der Waals interactions or hydrogen bonding. Neurotransmitters all contain OH or NH groups, which are prone to form hydrogen bonds with those of the neurotransmitter receptors. These could be perturbed by anaesthetics. Aromatic rings in amino acids can act as weak hydrogen bond acceptors. On the other hand the acidic hydrogen in halothane type anaesthetics are weak proton donors. These two facts together lead to a probable mechanism of action for all general anaesthetics.

  4. Triangular spin tubes with bond randomness

    NASA Astrophysics Data System (ADS)

    Miura, Yoko; Manaka, Hirotaka

    2013-06-01

    We performed X-ray diffraction, magnetic susceptibility, and magnetization experiments on nonequilateral triangular spin tubes composed of ?-KCr1- x Fe x F4 ( x = 0˜0.13), which consisted of one-dimensional Heisenberg antiferromagnets coexisting with geometrically-frustrated spin systems with bond randomness. The variation of lattice parameters with x may indicate that the Fe3+ ions constitute the low-spin state ( S = 1/2). As a result of analyses of the frustration factor and the spin-flop transition field, we found that the effect of geometrical spin frustration was enhanced and that the magnetic anisotropy was weakened as x was increased. Because these results are remarkably similar to the previous results for ?-KCr1- x Al x F4, the effect of the chemical impurity substitutions, whether they are magnetic or nonmagnetic ions, on ?-KCrF4 is clearly understood.

  5. Geometric Solids and Their Properties

    NSDL National Science Digital Library

    Illuminations; National Council of Teachers of Mathematics (NCTM)

    2000-01-01

    Explore geometric solids and their properties with these interactive tools, beginning with an introduction to the faces of basic polyhedra; counting the number of faces, edges, and corners (vertices) in various solids; discovering Euler's Formula; constructing physical models of geometric solids; and identifying which geometric solids can be made from given nets.

  6. The classical geometrization electromagnetism

    E-print Network

    C. A. Duarte

    2015-02-11

    Following the line of the history, if by one side the electromagnetic theory was consolidated on the 19th century, the emergence of the special and the general relativity theories on the 20th century opened possibilities of further developments, with the search for the unification of the gravitation and the electromagnetism on a single unified theory. Some attempts to the geometrization of the electromagnetism emerged in this context, where these first models resided strictly on a classical basis. Posteriorly, they were followed by more complete and embracing quantum field theories. The present work reconsiders the classical viewpoint, with the purpose of showing that in a first order of approximation the electromagnetism constitutes a geometric structure aside other phenomena as gravitation. Even though being limited, the model is consistent and offers the possibility of an experimental test of validity.

  7. CAM - Geometric systems integration

    NASA Astrophysics Data System (ADS)

    Dunlap, G. C.

    The integration of geometric and nongeometric information for efficient use of CAM is examined. Requirements for engineering drawings requested by management are noted to involve large volumes of nongeometric data to define the materials and quantity variables which impinge on the required design, so that the actual design may be the last and smaller step in the CAM process. Geometric classification and coding are noted to offer an alpha/numeric identifier for integrating the engineering design, manufacturing, and quality assurance functions. An example is provided of a turbine gear part coding in terms of polycode and monocode displays, showing a possible covering of more than 10 trillion features. Software is stressed as the key to integration of company-wide data.

  8. A generative geometric kernel

    Microsoft Academic Search

    Jacques Carette; Mustafa Elsheikh; Spencer Smith

    2011-01-01

    We present the design and implementation of a generative geometric kernel. The kernel generator is generic, type-safe, parametrized by many design-level choices and extensible. The resulting code has minimal traces of the design abstractions. We achieve genericity through a layered design deriving concepts from affine geometry, linear algebra and abstract algebra. We achieve parametrization and type-safety by using OCaml's module

  9. Geometrical deuteron stripping revisited

    SciTech Connect

    Neoh, Y. S.; Yap, S. L. [Plasma Research Technology Center, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-03-05

    We investigate the reality of the idea of geometrical deuteron stripping originally envisioned by Serber. By taking into account of realistic deuteron wavefunction, nuclear density, and nucleon stopping mean free path, we are able to estimate inclusive deuteron stripping cross section for deuteron energy up to before pion production. Our semiclassical model contains only one global parameter constant for all nuclei which can be approximated by Woods-Saxon or any other spherically symmetric density distribution.

  10. Chemical Bonding, again ionic bonding (in salts): transfer of e-

    E-print Network

    Zakarian, Armen

    Chemical Bonding, again · ionic bonding (in salts): transfer of e- · covalent bonding (organic molecules, non-metals): sharing e- · metallic bonding: electron pooling (delocalization) Lewis electron 3A 4A 5A 6A 7A 8A 2 3 (exceptions) #12;Ionic Bonding Model See sample problem 9.1 4Na + O2 ! 2Na2O

  11. Electronic, magnetic, and geometric structure of metallo-carbohedrenes

    Microsoft Academic Search

    B. V. Reddy; S. N. Khanna; P. Jena

    1992-01-01

    The energetics and the electronic, magnetic, and geometric structure of the metallo-carbohedrene Ti8C12 have been calculated self-consistently in the density functional formulation. The structure of Ti8C12 is a distorted dodecahedron with a binding energy of 6.1 electron volts per atom. The unusual stability is derived from covalent-like bonding between carbon atoms and between titanium and carbon atoms with no appreciable

  12. Architectural Layout Design Optimization

    NSDL National Science Digital Library

    Choudhary, Ruchi

    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.

  13. Chemical Bonds I

    ERIC Educational Resources Information Center

    Sanderson, R. T.

    1972-01-01

    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)

  14. The Sibling Bond.

    ERIC Educational Resources Information Center

    Bank, Stephen P.; Kahn, Michael D.

    The relationships among brothers and sisters are infinitely varied, but whatever their characteristics, these bonds last throughout life. This book examines the sibling relationship as a distinctive emotional, passionate, painful, and solacing power. Chapter 1, "Unraveling the Sibling Bond," addresses research on siblings and development of the…

  15. Convertible Bonds as \\

    Microsoft Academic Search

    Jeremy C. Stein

    1992-01-01

    This paper argues that corporations may use convertible bonds as an indirect (albeit possibly risky) method for getting equity into their capital structures in situations where adverse selection problems make a conventional stock issue unattractive. Unlike other theories of convertible bond issuance, the model of this paper highlights: 1) the importance of call provisions on convertibles; and 2) the significance

  16. PBGA wire bonding development

    Microsoft Academic Search

    W. K. Shu

    1996-01-01

    In a PBGA package, the existence of a glass transition temperature of 170~215°C for PCB substrate puts an upper ceiling to the usable wire bond temperature. The low thermal conductivity of PCB substrate and the need for a thicker material make fine pad pitch wire bonding even more difficult to do. To compensate for the limitation in thermal energy, high

  17. Optical bonding reinforced by femtosecond laser welding

    NASA Astrophysics Data System (ADS)

    Lacroix, Fabrice; Hélie, David; Vallée, Réal

    2011-09-01

    Previous work on welding of optical materials with ultrashort laser pulses demonstrated that the ability to achieve good contact between components limits the applicability of the technology to only very small components. We have overcome this limitation and demonstrated the capability to weld similar and dissimilar materials using femtosecond laser pulses over several mm2 areas between intimately contacted surfaces. Our joining process is realised in two steps. Firstly, the two pieces which must be joined are direct bonded, thereby inducing optical contact throughout the whole potentially bondable surface. Subsequently, the direct bond is reinforced by the inscription of femtosecond laser weld seams in a sealing pattern in order to enclose the central region of the direct bond. We demonstrated the applicability of this process to identical glass, dissimilar glass and glass-semiconductor. We also measured a mean threefold increase in joint strength for such bonds between fused silica windows with only a few welding seams. The final assembly is free from macroscopic surface deformations. Furthermore, by optimizing the laser exposure parameters, we can avoid microscopic defects inside and around weld seams. Finally, the bonding method does not alter the optical transmission properties at the center of the sealed region. As opposed to the use of adhesives, such bonds resist to important thermal constraints and are free from chemical contaminants, degassing and ageing. Potential applications may be considered in the fields of aerospace, laser manufacturing, semiconductor industry, solar cell protection, precision manufacturing and many more.

  18. Geometric phase in Bohmian mechanics

    SciTech Connect

    Chou, Chia-Chun, E-mail: chiachun@mail.utexas.ed [Institute for Theoretical Chemistry and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States); Wyatt, Robert E., E-mail: wyattre@mail.utexas.ed [Institute for Theoretical Chemistry and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States)

    2010-10-15

    Using the quantum kinematic approach of Mukunda and Simon, we propose a geometric phase in Bohmian mechanics. A reparametrization and gauge invariant geometric phase is derived along an arbitrary path in configuration space. The single valuedness of the wave function implies that the geometric phase along a path must be equal to an integer multiple of 2{pi}. The nonzero geometric phase indicates that we go through the branch cut of the action function from one Riemann sheet to another when we locally travel along the path. For stationary states, quantum vortices exhibiting the quantized circulation integral can be regarded as a manifestation of the geometric phase. The bound-state Aharonov-Bohm effect demonstrates that the geometric phase along a closed path contains not only the circulation integral term but also an additional term associated with the magnetic flux. In addition, it is shown that the geometric phase proposed previously from the ensemble theory is not gauge invariant.

  19. Diffusion Bonding of Silicon Carbide for MEMS-LDI Applications

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    A robust joining approach is critically needed for a Micro-Electro-Mechanical Systems-Lean Direct Injector (MEMS-LDI) application which requires leak free joints with high temperature mechanical capability. Diffusion bonding is well suited for the MEMS-LDI application. Diffusion bonds were fabricated using titanium interlayers between silicon carbide substrates during hot pressing. The interlayers consisted of either alloyed titanium foil or physically vapor deposited (PVD) titanium coatings. Microscopy shows that well adhered, crack free diffusion bonds are formed under optimal conditions. Under less than optimal conditions, microcracks are present in the bond layer due to the formation of intermetallic phases. Electron microprobe analysis was used to identify the reaction formed phases in the diffusion bond. Various compatibility issues among the phases in the interlayer and substrate are discussed. Also, the effects of temperature, pressure, time, silicon carbide substrate type, and type of titanium interlayer and thickness on the microstructure and composition of joints are discussed.

  20. The variational subspace valence bond method.

    PubMed

    Fletcher, Graham D

    2015-04-01

    The variational subspace valence bond (VSVB) method based on overlapping orbitals is introduced. VSVB provides variational support against collapse for the optimization of overlapping linear combinations of atomic orbitals (OLCAOs) using modified orbital expansions, without recourse to orthogonalization. OLCAO have the advantage of being naturally localized, chemically intuitive (to individually model bonds and lone pairs, for example), and transferrable between different molecular systems. Such features are exploited to avoid key computational bottlenecks. Since the OLCAO can be doubly occupied, VSVB can access very large problems, and calculations on systems with several hundred atoms are presented. PMID:25854233

  1. Ultrasonically bonded value assembly

    NASA Technical Reports Server (NTRS)

    Salvinski, R. J. (inventor)

    1975-01-01

    A valve apparatus capable of maintaining a fluid-tight seal over a relatively long period of time by releasably bonding a valve member to its seat is described. The valve member is bonded or welded to the seat and then released by the application of the same energy to the bond joint. The valve member is held in place during the bonding by a clamping device. An appropriate force device can activate the opening and closing of the valve member. Various combinations of material for the valve member and valve seat can be utilized to provide an adequate sealing bond. Aluminum oxide, stainless steel, inconel, tungsten carbide as hard materials and copper, aluminum, titanium, silver, and gold as soft materials are suggested.

  2. 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)

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

    2013-01-01

    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.

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

    Microsoft Academic Search

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

    1979-01-01

    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 (\\

  4. Adhesion, stability, and bonding at metal/metal-carbide interfaces: Al/WC Donald J. Siegel

    E-print Network

    Adams, James B

    Adhesion, stability, and bonding at metal/metal-carbide interfaces: Al/WC Donald J. Siegel yield substantial adhesion energies in the range 4­6 J/m¢ , bonding at the optimal C of an interface is the ideal work of adhesion,£¥¤§¦ [1], which is defined as the bond energy needed (per unit area

  5. Chlorotrinitromethane and its exceptionally short carbon-chlorine bond.

    PubMed

    Göbel, Michael; Tchitchanov, Boris H; Murray, Jane S; Politzer, Peter; Klapötke, Thomas M

    2009-06-01

    Compounds that deviate from the normal range of bonding can help to assess the strengths and weaknesses of the models currently used to describe chemical bonds. Furthermore, computer simulations of molecules require experimental data to describe accurately the energies and forces between interacting molecules. Compounds that contain the trinitromethyl group, with three nitro groups bonded to one carbon atom, show remarkable inter- and intramolecular effects. In this paper, we report the structural features of chlorotrinitromethane in the solid state and present the first reliable solid-state geometry parameters of an ?-halogen derivative of the trinitromethyl pseudohalogen. We found several intriguing geometrical features in terms of intra- and intermolecular interactions, as well as an exceptionally short carbon-chlorine bond (1.694(1) Å). Using a combined crystallographic and computational approach, we show that these effects can be described in terms of the computed electrostatic potential of the molecular surface. PMID:21378853

  6. The occurrence of geometric polyprenol isomers in the rubber-producing plant, Eucommia ulmoides oliver

    Microsoft Academic Search

    Takeshi Bamba; Ei-ichiro Fukusaki; Shin-ichiro Kajivama; Koichi Ute; Tatsuki Kitayama; Akio Kobayashi

    2001-01-01

    The chain length and geometric isomerism of polyprenols from Eucommia ulmoides Oliver were analyzed using supercritical fluid chromatography. After intensive effort to establish separation conditions\\u000a for geometric isomers, a phenyl-bonded silica gel-packed column was found that cleanly separated poly-trans and-cis prenols. The presence of longchain poly-trans prenols (>9 mers) was confirmed for the first time in plants. Trans isomers were

  7. Diffusion Bonding of Silicon Carbide Ceramics using Titanium Interlayers

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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.

  8. Kissing bonds A kissing bond is adhesively bonded but holds little of the strength usually

    E-print Network

    Sóbester, András

    Kissing bonds · A kissing bond is adhesively bonded but holds little of the strength usually weight saving and excellent stress transfer. · The ability to reliably assess defects in adhesive bonds · To develop a non destructive method to assess the integrity of adhesive bonds using pulsed phase thermography

  9. Ultrasonic friction power during Al wire wedge-wedge bonding

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

    Al wire bonding, also called ultrasonic wedge-wedge bonding, is a microwelding process used extensively in the microelectronics industry for interconnections to integrated circuits. The bonding wire used is a 25?m diameter AlSi1 wire. A friction power model is used to derive the ultrasonic friction power during Al wire bonding. Auxiliary measurements include the current delivered to the ultrasonic transducer, the vibration amplitude of the bonding tool tip in free air, and the ultrasonic force acting on the bonding pad during the bond process. The ultrasonic force measurement is like a signature of the bond as it allows for a detailed insight into mechanisms during various phases of the process. It is measured using piezoresistive force microsensors integrated close to the Al bonding pad (Al-Al process) on a custom made test chip. A clear break-off in the force signal is observed, which is followed by a relatively constant force for a short duration. A large second harmonic content is observed, describing a nonsymmetric deviation of the signal wave form from the sinusoidal shape. This deviation might be due to the reduced geometrical symmetry of the wedge tool. For bonds made with typical process parameters, several characteristic values used in the friction power model are determined. The ultrasonic compliance of the bonding system is 2.66?m/N. A typical maximum value of the relative interfacial amplitude of ultrasonic friction is at least 222nm. The maximum interfacial friction power is at least 11.5mW, which is only about 4.8% of the total electrical power delivered to the ultrasonic generator.

  10. Random Geometric Prior Forest for Multiclass Object Segmentation.

    PubMed

    Liu, Xiao; Song, Mingli; Tao, Dacheng; Bu, Jiajun; Chen, Chun

    2015-10-01

    Recent advances in object detection have led to the development of segmentation by detection approaches that integrate top-down geometric priors for multiclass object segmentation. A key yet under-addressed issue in utilizing top-down cues for the problem of multiclass object segmentation by detection is efficiently generating robust and accurate geometric priors. In this paper, we propose a random geometric prior forest scheme to obtain object-adaptive geometric priors efficiently and robustly. In the scheme, a testing object first searches for training neighbors with similar geometries using the random geometric prior forest, and then the geometry of the testing object is reconstructed by linearly combining the geometries of its neighbors. Our scheme enjoys several favorable properties when compared with conventional methods. First, it is robust and very fast because its inference does not suffer from bad initializations, poor local minimums or complex optimization. Second, the figure/ground geometries of training samples are utilized in a multitask manner. Third, our scheme is object-adaptive but does not require the labeling of parts or poselets, and thus, it is quite easy to implement. To demonstrate the effectiveness of the proposed scheme, we integrate the obtained top-down geometric priors with conventional bottom-up color cues in the frame of graph cut. The proposed random geometric prior forest achieves the best segmentation results of all of the methods tested on VOC2010/2012 and is 90 times faster than the current state-of-the-art method. PMID:25974937

  11. Wafer-Level Thermocompression Bonds

    E-print Network

    Tsau, Christine H.

    Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding without the application of an electric field or complicated pre-bond cleaning procedure. The presence of a ductile ...

  12. Geometric Brownian Motion Consider the geometric Brownian motion process

    E-print Network

    Lyuu, Yuh-Dauh

    Geometric Brownian Motion · Consider the geometric Brownian motion process Y (t) eX(t) ­ X(t) is a (µ, ) Brownian motion. · As Y/X = Y and 2 Y/X2 = Y , Ito's formula (51) on p. 453 implies dY Y = µ-Dauh Lyuu, National Taiwan University Page 459 Product of Geometric Brownian Motion Processes · Let d

  13. Geometrical scaling law for laser shock processing

    NASA Astrophysics Data System (ADS)

    Wu, Xianqian; Tan, Qingming; Huang, Chenguang

    2013-07-01

    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.

  14. Geometric integration in Born-Oppenheimer molecular dynamics.

    PubMed

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

    2011-12-14

    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

  15. Parallel Geometric Multigrid for Global Weather Prediction S.D. Buckeridge and R. Scheichl

    E-print Network

    Burton, Geoffrey R.

    Parallel Geometric Multigrid for Global Weather Prediction S.D. Buckeridge and R. Scheichl Bath Geometric Multigrid for Global Weather Prediction Sean D. Buckeridge and Robert Scheichl Dept. Mathematical. The parallel implementation scales almost optimally on up to 64 processors, so that a global solve of the quasi

  16. Parallel Geometric Multigrid for Global Weather Prediction S.D. Buckeridge and R. Scheichl

    E-print Network

    Wirosoetisno, Djoko

    Parallel Geometric Multigrid for Global Weather Prediction S.D. Buckeridge and R. Scheichl Bath Geometric Multigrid for Global Weather Prediction Sean Buckeridge and Robert Scheichl Dept. Mathematical implementation scales almost optimally on up to 256 processors, so that a global solve of the quasi- geostrophic

  17. Encoding geometric and non-geometric information: a study with evolved agents

    Microsoft Academic Search

    Michela Ponticorvo; Orazio Miglino

    2010-01-01

    Vertebrate species use geometric information and non-geometric or featural cues to orient. Under some circumstances, when\\u000a both geometric and non-geometric information are available, the geometric information overwhelms non-geometric cues (geometric\\u000a primacy). In other cases, we observe the inverse tendency or the successful integration of both cues. In past years, modular\\u000a explanations have been proposed for the geometric primacy: geometric and

  18. Gold Thermocompression Wafer Bonding

    E-print Network

    Spearing, S. Mark

    Thermocompression bonding of gold is a promising technique for the fabrication and packaging microelectronic and MEMS devices. The use of a gold interlayer and moderate temperatures and pressures results in a hermetic, ...

  19. Characterization of anodic bonding

    E-print Network

    Tudryn, Carissa Debra, 1978-

    2004-01-01

    Anodic bonding is a common process used in MicroElectroMechanical Systems (MEMS) device fabrication and packaging. Polycrystalline chemical vapor deposited (CVD) silicon carbide (SiC) is emerging as a new MEMS device and ...

  20. Hydrogen bonds animation

    NSDL National Science Digital Library

    Northland Community and Technical College Biology Department

    2007-12-12

    This color animation of water molecules interacting and forming hydrogen bonds is a hybrid between a PowerPoint slide show an an animation. Students can replay portions or click next if they do not need to replay a segment.

  1. Junk-Bond Colleges.

    ERIC Educational Resources Information Center

    Van Der Werf, Martin

    2003-01-01

    Describes how a long-predicted decline in the fortunes of small private colleges is beginning to show up in the bond market, as the number of colleges now rated in the junk category has nearly doubled. (EV)

  2. Bonding aerogels with polyurethanes

    SciTech Connect

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

    1989-11-01

    Aerogels, porous silica glasses with ultra-fine cell size (30nm), are made by a solution gelation (sol-gel) process. The resulting gel is critical point dried to densities from 0.15--0.60 g/cc. This material is machinable, homogeneous, transparent, coatable and bondable. To bond aerogel an adhesive should have long cure time, no attack on the aerogel structure, and high strength. Several epoxies and urethanes were examined to determine if they satisfied these conditions. Bond strengths above 13 psi were found with double bubble and DP-110 epoxies and XI-208/ODA-1000 and Castall U-2630 urethanes. Hardman Kalex Tough Stuff'' A-85 hardness urethane gave 18 psi bond strength. Hardman A-85, Tuff-Stuff'' was selected for further evaluation because it produced bond strengths comparable to the adherend cohesive strength. 5 refs., 2 figs.

  3. Roof bolt bond tester

    SciTech Connect

    Not Available

    1982-01-01

    An intrinsically safe, electronic instrument has been developed that determines the holding quality of a fully grouted roof bolt by testing the integrity of the resin bond to both the bolt and to the surrounding rock.

  4. Wire bonding process impact on low-k dielectric material in damascene copper integrated circuits

    Microsoft Academic Search

    Vaidyanathan Kripesh; Mohandass Sivakumar; Loon Aik Lim; Rakesh Kumar; Mahadevan K. Iyer

    2002-01-01

    This study investigates wire bonding impact on low-k dielectric material used in dual damascene copper integrated circuits. The paper focuses on wire bond process optimization required for devices with soft low-k dielectric material compared to device with hard standard silicon dioxide dielectric. A fine pitch (60 ?m bond pitch) wire bonding process was established on test vehicles with SiO2 and

  5. All about Chemical Bonding

    NSDL National Science Digital Library

    Lower, Stephen

    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.

  6. Protein Folding: A New Geometric Analysis

    E-print Network

    Walter A. Simmons; Joel L. Weiner

    2008-09-11

    A geometric analysis of protein folding, which complements many of the models in the literature, is presented. We examine the process from unfolded strand to the point where the strand becomes self-interacting. A central question is how it is possible that so many initial configurations proceed to fold to a unique final configuration. We put energy and dynamical considerations temporarily aside and focus upon the geometry alone. We parameterize the structure of an idealized protein using the concept of a ribbon from differential geometry. The deformation of the ribbon is described by introducing a generic twisting Ansatz. The folding process in this picture entails a change in shape guided by the local amino acid geometry. The theory is reparamaterization invariant from the start, so the final shape is independent of folding time. We develop differential equations for the changing shape. For some parameter ranges, a sine-Gordon torsion soliton is found. This purely geometric waveform has properties similar to dynamical solitons. Namely: A threshold distortion of the molecule is required to initiate the soliton, after which, small additional distortions do not change the waveform. In this analysis, the soliton twists the molecule until bonds form. The analysis reveals a quantitative relationship between the geometry of the amino acids and the folded form.

  7. Water's Hydrogen Bond Strength

    E-print Network

    Martin Chaplin

    2007-06-10

    Water is necessary both for the evolution of life and its continuance. It possesses particular properties that cannot be found in other materials and that are required for life-giving processes. These properties are brought about by the hydrogen bonded environment particularly evident in liquid water. Each liquid water molecule is involved in about four hydrogen bonds with strengths considerably less than covalent bonds but considerably greater than the natural thermal energy. These hydrogen bonds are roughly tetrahedrally arranged such that when strongly formed the local clustering expands, decreasing the density. Such low density structuring naturally occurs at low and supercooled temperatures and gives rise to many physical and chemical properties that evidence the particular uniqueness of liquid water. If aqueous hydrogen bonds were actually somewhat stronger then water would behave similar to a glass, whereas if they were weaker then water would be a gas and only exist as a liquid at sub-zero temperatures. The overall conclusion of this investigation is that water's hydrogen bond strength is poised centrally within a narrow window of its suitability for life.

  8. Bond order instabilities in a correlated two-dimensional metal Andrea Allais, Johannes Bauer, and Subir Sachdev

    E-print Network

    , with arbitrary wavevector and tunable form factor. Depending on parameters, we find d-wave bond density wave-ray scattering. Collectively, the experiments point to the existence of incommensurate charge correlations-oxygen bonds, and ap- pears to be related to geometric properties of the Fermi surface [13] (Fig 1

  9. Bonding and solvation preferences of nickel complexes [Ni(S 2PR 2) 2] (R=H, Me, OMe) according a natural bond orbital analysis

    Microsoft Academic Search

    Alexis Otero-Calvi; Gabriel Aullon; Santiago Alvarez; Luis A. Montero; Wolf-Dieter Stohrer

    2006-01-01

    Calculations based on density functional methods (DFT) are carried out for the dithiophosphorus nickel complexes of the type [Ni(S2PR2)2] where R=H, Me and OMe. Geometrical parameters obtained by the calculation are in good agreement with reported X-ray structure. A Natural Bond Orbital analysis indicates that the Ni–S bond is mainly governed by charge transfer via a strong delocalization of the

  10. 30 CFR 581.33 - Bonds and bonding requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Resources 2 2013-07-01 2013-07-01 false Bonds and bonding requirements. 581.33 Section 581.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations § 581.33 Bonds and bonding requirements. (a) When the leasing notice...

  11. Fair Scheduling on Parallel Bonded Channels with Intersecting Bonding Groups

    E-print Network

    Martin, Jim

    Fair Scheduling on Parallel Bonded Channels with Intersecting Bonding Groups Gongbing Hong, James for providing weighted sharing of aggregate capacity in networks having parallel bonded channels in which a single channel may simultaneously be a member of multiple bonding groups. Our work is motivated

  12. 30 CFR 281.33 - Bonds and bonding requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Resources 2 2011-07-01 2011-07-01 false Bonds and bonding requirements. 281.33 Section 281.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations § 281.33 Bonds and bonding requirements. (a) When the leasing notice...

  13. 30 CFR 581.33 - Bonds and bonding requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Resources 2 2014-07-01 2014-07-01 false Bonds and bonding requirements. 581.33 Section 581.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations § 581.33 Bonds and bonding requirements. (a) When the leasing notice...

  14. 30 CFR 581.33 - Bonds and bonding requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Resources 2 2012-07-01 2012-07-01 false Bonds and bonding requirements. 581.33 Section 581.33 Mineral Resources...CONTINENTAL SHELF Financial Considerations § 581.33 Bonds and bonding requirements. (a) When the leasing notice...

  15. Coherent Control of Bond Making

    E-print Network

    Liat Levin; Wojciech Skomorowski; Leonid Rybak; Ronnie Kosloff; Christiane P. Koch; Zohar Amitay

    2014-11-06

    We demonstrate for the first time coherent control of bond making, a milestone on the way to coherent control of photo-induced bimolecular chemical reactions. In strong-field multiphoton femtosecond photoassociation experiments, we find the yield of detected magnesium dimer molecules to be enhanced for positively chirped pulses and suppressed for negatively chirped pulses. Our ab initio model shows that control is achieved by purification via Franck-Condon filtering combined with chirp-dependent Raman transitions. Experimental closed-loop phase optimization using a learning algorithm yields an improved pulse that utilizes vibrational coherent dynamics in addition to chirp-dependent Raman transitions. Our results show that coherent control of binary photo-reactions is feasible even under thermal conditions.

  16. Geometric Exponents of Dilute Loop Models

    NASA Astrophysics Data System (ADS)

    Provencher, Guillaume; Saint-Aubin, Yvan; Pearce, Paul A.; Rasmussen, Jørgen

    2012-04-01

    The fractal dimensions of the hull, the external perimeter and of the red bonds are measured through Monte Carlo simulations for dilute minimal models, and compared with predictions from conformal field theory and SLE methods. The dilute models used are those first introduced by Nienhuis. Their loop fugacity is ?=-2 \\cos(?/bar{kappa}) where the parameter bar{kappa} is linked to their description through conformal loop ensembles. It is also linked to conformal field theories through their central charges c(bar{kappa})=13-6(bar{kappa}+bar{kappa}^{-1}) and, for the minimal models of interest here, bar{kappa}=p/p' where p and p' are two coprime integers. The geometric exponents of the hull and external perimeter are studied for the pairs ( p, p')=(1,1),(2,3),(3,4),(4,5),(5,6),(5,7), and that of the red bonds for ( p, p')=(3,4). Monte Carlo upgrades are proposed for these models as well as several techniques to improve their speeds. The measured fractal dimensions are obtained by extrapolation on the lattice size H, V??. The extrapolating curves have large slopes; despite these, the measured dimensions coincide with theoretical predictions up to three or four digits. In some cases, the theoretical values lie slightly outside the confidence intervals; explanations of these small discrepancies are proposed.

  17. Geometrical pattern learning

    SciTech Connect

    Goldberg, P.W.

    1993-04-01

    In this paper we consider the problem of learning the positions of spheres in metric spaces, given as data randomly drawn points classified according to whether they are internal or external to an unknown sphere. The particular metrics under consideration are geometrical shape metrics, and the results are intended to be applicable to the problem of learning to identify a shape from related shapes classified according to whether they resemble it visually. While it is typically NP-hard to locate a central point for a hypothesis sphere, we find that it is however often possible to obtain a non-spherical hypothesis which can accurately predict whether further random points lie within the unknown sphere. We exhibit algorithms which achieve this, and in the process indicate useful general techniques for computational learning. Finally we exhibit a natural shape metric and show that it defines a class of spheres not predictable in this sense, subject to standard cryptographic assumptions.

  18. Noncommutative geometric regularization

    SciTech Connect

    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

    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.}

  19. Silicon Wafer Bonding by Modified Surface Activated Bonding Methods

    Microsoft Academic Search

    Chenxi Wang; E. Higurashi; T. Suga

    2007-01-01

    8-inch Si-Si wafer bonding at room temperature is performed by means of two modified surface activated bonding (SAB) methods respectively, namely the SAB with nano-adhesion layer and sequential plasma activated bonding (SPAB). And post-annealing processes in atmospheric air utilized do not aim to improve the bonding strength, but to investigate void formation if the bonded wafers heated in subsequent heated

  20. Advanced copper wire bonding technology

    Microsoft Academic Search

    Hong Meng Ho

    2010-01-01

    Wire bonding is the most dominant form of first-level chip interconnects in microelectronics with gold wire bonding taking the lead for the past few decades. Today, it is evident that the shift from gold to copper wire bonding is genuinely picking up, due to both a surge in gold prices and recent developments in copper wire bonding technology. The course

  1. Wire bonds over active circuits

    Microsoft Academic Search

    Gail Heinen; Roger J. Stierman; Darvin Edwards; L. Nye

    1994-01-01

    A reliable process-for wire bonding over active integrated circuits, which are subsequently assembled in plastic packages, has been developed. This technology accommodates reducing the silicon die area required for bond pads and for on-chip bussing. Further, it supports area array wire bonding by allowing larger bond pads with relaxed pitch without sacrificing silicon area. This is accomplished by processing an

  2. Geometric Algebra for Subspace Operations

    Microsoft Academic Search

    T. A. Bouma; L. Dorst; H. G. J. Pijls

    2001-01-01

    The set theory relations \\\\in, \\\\backslash, \\\\Delta, \\\\cap, and \\\\cup have corollaries in subspace relations. Geometric Algebra is introduced as the ideal framework to explore these subspace operations. The relations \\\\in, \\\\backslash, and \\\\Delta are easily subsumed by Geometric Algebra for Euclidean metrics. A short computation shows that the meet (\\\\cap) and join (\\\\cup) are resolved in a projection operator

  3. Compass routing on geometric networks

    Microsoft Academic Search

    Evangelos Kranakis; Harvinder Singh; Jorge Urrutia

    1999-01-01

    this paper we study local routing algorithms on geometric networks. Formally speaking, suppose that we want to travel from a vertex s to a vertex t of a geometric network. A routing algorithm is called a local routing algorithm if it satisfies the following conditions:

  4. Circle actions in geometric quantisation

    NASA Astrophysics Data System (ADS)

    Solha, Romero

    2015-01-01

    The aim of this article is to present unifying proofs for results in geometric quantisation with real polarisations by exploring the existence of symplectic circle actions. It provides an extension of Rawnsley's results on the Kostant complex, and gives a partial result for the focus-focus contribution to geometric quantisation; as well as, an alternative proof for theorems of ?niatycki and Hamilton.

  5. Geometrical Phases in Nonlinear Oscillators

    Microsoft Academic Search

    Radha Balakrishnan; Indubala Satija

    2004-01-01

    We characterize the geometrical and topological aspects of a classical dynamical system by associating a geometric phase with a phase space trajectory. Unlike Hannay's angle, this phase can be defined for non-integrable, as well as dissipative systems. Further, the path underlying this ``anholonomy'' is not in an external parameter space, but in a certain \\

  6. A Primer on Geometric Mechanics

    E-print Network

    Christian Lessig

    2012-06-14

    Geometric mechanics is usually studied in applied mathematics and most introductory texts are hence aimed at a mathematically minded audience. The present note tries to provide the intuition of geometric mechanics and to show the relevance of the subject for an understanding of "mechanics".

  7. Hyperconjugation-mediated solvent effects in phosphoanhydride bonds

    PubMed Central

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

    2012-01-01

    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 anti-periplanar orientation, the overall magnitude of the anomeric effect is compensated approximately by the other lone pair as it becomes more anti-periplanar. Furthermore, solvent modulation of the anomeric effect is not restricted to the anti-periplanar 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 non-bridging 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

  8. Insulation bonding test system

    NASA Technical Reports Server (NTRS)

    Beggs, J. M.; Johnston, G. D.; Coleman, A. D.; Portwood, J. N.; Saunders, J. M.; Redmon, J. W.; Porter, A. C. (inventors)

    1984-01-01

    A method and a system for testing the bonding of foam insulation attached to metal is described. The system involves the use of an impacter which has a calibrated load cell mounted on a plunger and a hammer head mounted on the end of the plunger. When the impacter strikes the insulation at a point to be tested, the load cell measures the force of the impact and the precise time interval during which the hammer head is in contact with the insulation. This information is transmitted as an electrical signal to a load cell amplifier where the signal is conditioned and then transmitted to a fast Fourier transform (FFT) analyzer. The FFT analyzer produces energy spectral density curves which are displayed on a video screen. The termination frequency of the energy spectral density curve may be compared with a predetermined empirical scale to determine whether a igh quality bond, good bond, or debond is present at the point of impact.

  9. Adhesive bond degradation sensor

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

    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.

  10. Geometric optical image aberrations of single and double mirrors.

    PubMed

    Tschunko, H F; Hurwitz, M G

    1969-02-01

    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

  11. Harvesting Energy Using a Thin Unimorph Prestressed Bender: Geometrical Effects

    Microsoft Academic Search

    Karla Mossi; Christopher Green; Zoubeida Ounaies; Esther Hughes

    2005-01-01

    Mathematical models and circuitry necessary for optimal energy conversion have been developed for piezoelectric devices because of their ability to convert mechanical energy to electrical energy. The piezoelectric device that is the focus of this study is a curved, thin unimorph prestressed bender. This device consists of layers of piezoelectric material, polyimide, and metal bonded at high temperatures. Effects of

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

    PubMed

    Ruedenberg, Klaus; Schmidt, Michael W

    2009-03-12

    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

  13. [Geometrical property of navigation].

    PubMed

    Watanabe, Toshio

    2003-08-01

    There is a tendency that a blind or a blind-folded subject fails to return to a starting point within the range of errors when he or she walks to a place, next turns to right or left, and then comes back to the starting point. We studied this tendency from a non-Euclidean geometrical point of view. In Experiment 1, total of 28 blind-folded subjects walked to construct a square, a regular triangle and a circle. The result showed that the location of the final reaching point was on the fronto-right side of the starting point in the square and triangle conditions and went over the starting point in the circle condition. In Experiment 2, 15 subjects judged visual properties (angles and distances) of a triangle and constructed the triangle by walking. The walking loci were compared with the visual properties. It was found that the walking loci were curved, differing from the visual properties. These results implied that the walking loci agree with the nature of elliptic geometry. PMID:14584253

  14. The Calculation of Accurate Metal-Ligand Bond Energies

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W.; Partridge, Harry, III; Ricca, Alessandra; Arnold, James O. (Technical Monitor)

    1997-01-01

    The optimization of the geometry and calculation of zero-point energies are carried out at the B3LYP level of theory. The bond energies are determined at this level, as well as at the CCSD(T) level using very large basis sets. The successive OH bond energies to the first row transition metal cations are reported. For most systems there has been an experimental determination of the first OH. In general, the CCSD(T) values are in good agreement with experiment. The bonding changes from mostly covalent for the early metals to mostly electrostatic for the late transition metal systems.

  15. Free vibration of functionally graded material beams with surface-bonded piezoelectric layers in thermal environment

    Microsoft Academic Search

    Shi-rong Li; Hou-de Su; Chang-jun Cheng

    2009-01-01

    Free vibration of statically thermal postbuckled functionally graded material (FGM) beams with surface-bonded piezoelectric\\u000a layers subject to both temperature rise and voltage is studied. By accurately considering the axial extension and based on\\u000a the Euler-Bernoulli beam theory, geometrically nonlinear dynamic governing equations for FGM beams with surface-bonded piezoelectric\\u000a layers subject to thermo-electromechanical loadings are formulated. It is assumed that the

  16. Optical traps with geometric aberrations

    SciTech Connect

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

    2006-05-20

    We assess the influence of geometric aberrations on the in-plane performance of optical traps by studying the dynamics of trapped colloidal spheres in deliberately distorted holographic optical tweezers. The lateral stiffness of the traps turns out to be insensitive to moderate amounts of coma, astigmatism, and spherical aberration. Moreover holographic aberration correction enables us to compensate inherent shortcomings in the optical train, thereby adaptively improving its performance. We also demonstrate the effects of geometric aberrations on the intensity profiles of optical vortices, whose readily measured deformations suggest a method for rapidly estimating and correcting geometric aberrations in holographic trapping systems.

  17. Repeating Decimals and Geometric Series

    NSDL National Science Digital Library

    2011-01-01

    This activity begins by reviewing conversions between fractions and decimals with an emphasis on repeating decimals. The formula for the partial sum of a geometric series is bypassed and students are directed to use find partial sums by using the “multiply, subtract, and solve” technique which mimics the derivation of the formula for the partial sum of a geometric series. This sets the stage for students to quickly find the fraction representation of a repeating decimal number. This activity would be well-suited as a prelude to introducing infinite and partial sums of geometric sequences.

  18. Bond University Queensland, Australia

    E-print Network

    Duchowski, Andrew T.

    Private fiber optic Internet network upon subscription o Within walking distance to campus o Large lagoon pool with water features overlooking Lake Orr o An RA from Bond University lives on site The Retreat o Adjacent to The Retreat o 2 and 3 bedrooms o Gourmet kitchen - stone kitchen tops & glass splash backs

  19. Investing in Bonds 

    E-print Network

    Johnson, Jason; Polk, Wade

    2002-08-12

    maturi- ty tend to have higher interest E-163 8-02 INVESTING IN BONDS Jason Johnson and Wade Polk* *Assistant Professor and Extension Economist?Management, and Extension Program Specialist?Risk Management, The Texas A&M University System rates (coupons...

  20. Thread bonds in molecules

    E-print Network

    Ivlev, B

    2015-01-01

    Unusual chemical bonds are proposed. Each bond is almost covalent but is characterized by the thread of a small radius $\\sim 0.6\\times 10^{-11}$cm, between two nuclei in a molecule. The main electron density is concentrated outside the thread as in a covalent bond. The thread is formed by the electron wave function which has a tendency to be singular on it. The singularity along the thread is cut off by electron "vibrations" due to the interaction with zero point electromagnetic oscillations. The electron energy has its typical value of (1-10)eV. Due to the small tread radius the uncertainty of the electron momentum inside the thread is large resulting in a large electron kinetic energy $\\sim 1 MeV$. This energy is compensated by formation of a potential well due to the reduction of the energy of electromagnetic zero point oscillations. This is similar to formation of a negative van der Waals potential. Thread bonds are stable and cannot be created or destructed in chemical or optical processes.

  1. Bonding silicones with epoxies

    Microsoft Academic Search

    Tira

    1980-01-01

    It is shown that silicones, both room temperature vulcanizing (RTV) and millable rubber (press cured) can be successfully bonded to other materials using plasma treatment and epoxy adhesives. The plasma treatment using dry air atmosphere increases the surface energy of the silicone and thus provides a lower water contact angle. This phenomenon allows the epoxy adhesive to wet the silicone

  2. Bonding with the Past.

    ERIC Educational Resources Information Center

    Common Ground: Archeology and Ethnography in the Public Interest, 1998

    1998-01-01

    An interview with Linda Mayro, archaeologist and cultural resources manager for Pima County, Arizona, discusses efforts of local groups to preserve local Native-American and Mexican cultural-heritage sites in oppositon to commercial land developers. A public information campaign led to passage of a $6.4 million historic preservation bond. (SAS)

  3. Durability of bonded assemblies

    Microsoft Academic Search

    Karim Benzarti; Pierre Argoul; Francesco Freddi; Michel Frémond; Thi Hoa Tam Nguyen

    2009-01-01

    An advanced model coupling bulk and interfacial damages is proposed in order to predict the durability of adhesively bonded joints. The underlying theory, based on the principle of virtual power, is briefly presented in the first part of the paper. The second part is devoted to the validation the cited theory. The model is first implemented to describe the damage

  4. Photochemical tissue bonding

    DOEpatents

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

    2012-01-10

    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.

  5. Mirror profile optimization for nano-focusing KB mirror

    SciTech Connect

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

    2010-06-23

    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.

  6. Geometric algorithms for reconfigurable structures

    E-print Network

    Benbernou, Nadia M

    2011-01-01

    In this thesis, we study three problems related to geometric algorithms of reconfigurable structures. In the first problem, strip folding, we present two universal hinge patterns for a strip of material that enable the ...

  7. Guitars, Violins, and Geometric Sequences

    ERIC Educational Resources Information Center

    Barger, Rita; Haehl, Martha

    2007-01-01

    This article describes middle school mathematics activities that relate measurement, ratios, and geometric sequences to finger positions or the placement of frets on stringed musical instruments. (Contains 2 figures and 2 tables.)

  8. Current Concept of Geometrical Accuracy

    NASA Astrophysics Data System (ADS)

    Görög, Augustín; Görögová, Ingrid

    2014-06-01

    Within the solving VEGA 1/0615/12 research project "Influence of 5-axis grinding parameters on the shank cutte?s geometric accuracy", the research team will measure and evaluate geometrical accuracy of the produced parts. They will use the contemporary measurement technology (for example the optical 3D scanners). During the past few years, significant changes have occurred in the field of geometrical accuracy. The objective of this contribution is to analyse the current standards in the field of geometric tolerance. It is necessary to bring an overview of the basic concepts and definitions in the field. It will prevent the use of outdated and invalidated terms and definitions in the field. The knowledge presented in the contribution will provide the new perspective of the measurement that will be evaluated according to the current standards.

  9. Nickel-palladium bond pads for copper wire bonding

    Microsoft Academic Search

    Horst Clauberg; Petra Backus; Bob Chylak

    2011-01-01

    The semiconductor packaging industry is undergoing a step-change transition from gold to copper wire bonding brought on by a quadrupling of gold cost over the last 8years. The transition has been exceptionally rapid over the last 3years and virtually all companies in the industry now have significant copper wire bonding production. Among the challenges to copper wire bonding is the

  10. Geometric Algebra for Subspace Operations

    Microsoft Academic Search

    T. A. Bouma; L. Dorst; H. G. J. Pijls

    2001-01-01

    The set theory relations \\\\in, \\\\backslash, \\\\Delta, \\\\cap, and \\\\cup have\\u000acorollaries in subspace relations. Geometric Algebra is introduced as the ideal\\u000aframework to explore these subspace operations. The relations \\\\in, \\\\backslash,\\u000aand \\\\Delta are easily subsumed by Geometric Algebra for Euclidean metrics. A\\u000ashort computation shows that the meet (\\\\cap) and join (\\\\cup) are resolved in a\\u000aprojection operator

  11. Geometric calculations of thin shells

    E-print Network

    Wright, William Dennis

    1967-01-01

    GEOMETRIC CALCULATIONS OF THIN SHELLS A Thesis by WILLIAM DENNIS WRIGHT Submitted to the Graduate College of the Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1967 Major Subject...: Computer Science GEOMETRIC CALCULATIONS OF THIN SHELLS A Thesis by WILLIAM DENNIS WRIGHT Approved as to style and content by: (Chairman of Committee) (Nember) August 1967 ACKNOWLEDGMENT I extend my sincerest appreciation to all of those who have...

  12. Palladium- and Nickel-Catalyzed Carbon–Carbon Bond Insertion Reactions with Alkylidenesilacyclopropanes

    PubMed Central

    Buchner, Kay M.; Woerpel, K. A.

    2010-01-01

    Palladium and nickel catalysts promoted highly selective carbon–carbon bond insertion reactions with di-tert-butyl-alkylidenesilacyclopropanes. Pd(PPh3)4 was demonstrated to be the optimal catalyst, allowing for a variety of carbon–carbon ?-bond insertion reactions. Depending on the nature of the carbon–carbon ? bond, the insertion reaction proceeded with either direct insertion into the carbon(sp2)–silicon bond or with allylic transposition. Ring-substituted alkylidenesilacyclopropanes required a nickel catalyst to afford insertion products. Using Ni(cod)2 as the carbon–carbon bond insertion catalyst, new double alkyne insertion products and alkene isomerization products were observed. PMID:20419110

  13. Kernel density estimation applied to bond length, bond angle, and torsion angle distributions.

    PubMed

    McCabe, Patrick; Korb, Oliver; Cole, Jason

    2014-05-27

    We describe the method of kernel density estimation (KDE) and apply it to molecular structure data. KDE is a quite general nonparametric statistical method suitable even for multimodal data. The method generates smooth probability density function (PDF) representations and finds application in diverse fields such as signal processing and econometrics. KDE appears to have been under-utilized as a method in molecular geometry analysis, chemo-informatics, and molecular structure optimization. The resulting probability densities have advantages over histograms and, importantly, are also suitable for gradient-based optimization. To illustrate KDE, we describe its application to chemical bond length, bond valence angle, and torsion angle distributions and show the ability of the method to model arbitrary torsion angle distributions. PMID:24746022

  14. ChemTeacher: Metallic Bonds

    NSDL National Science Digital Library

    2012-07-20

    ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Metallic Bonds page includes resources for teaching students about metallic bonding.

  15. ChemTeacher: Ionic Bonds

    NSDL National Science Digital Library

    2012-07-20

    ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Ionic Bonds page includes resources for teaching students about ionic bonding.

  16. ChemTeacher: Covalent Bonds

    NSDL National Science Digital Library

    2012-07-20

    ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Covalent Bonds page includes resources for teaching students about covalent bonding.

  17. The Illiquidity of Corporate Bonds

    E-print Network

    Bao, Jack

    This paper examines the illiquidity of corporate bonds and its asset-pricing implications. Using transactions data from 2003 to 2009, we show that the illiquidity in corporate bonds is substantial, significantly greater ...

  18. Geometric and Electronic Properties of Edge-decorated Graphene Nanoribbons

    NASA Astrophysics Data System (ADS)

    Chang, Shen-Lin; Lin, Shih-Yang; Lin, Shih-Kang; Lee, Chi-Hsuan; Lin, Ming-Fa

    2014-08-01

    Edge-decorated graphene nanoribbons are investigated with the density functional theory; they reveal three stable geometric structures. The first type is a tubular structure formed by the covalent bonds of decorating boron or nitrogen atoms. The second one consists of curved nanoribbons created by the dipole-dipole interactions between two edges when decorated with Be, Mg, or Al atoms. The final structure is a flat nanoribbon produced due to the repulsive force between two edges; most decorated structures belong to this type. Various decorating atoms, different curvature angles, and the zigzag edge structure are reflected in the electronic properties, magnetic properties, and bonding configurations. Most of the resulting structures are conductors with relatively high free carrier densities, whereas a few are semiconductors due to the zigzag-edge-induced anti-ferromagnetism.

  19. Geometric and electronic properties of edge-decorated graphene nanoribbons.

    PubMed

    Chang, Shen-Lin; Lin, Shih-Yang; Lin, Shih-Kang; Lee, Chi-Hsuan; Lin, Ming-Fa

    2014-01-01

    Edge-decorated graphene nanoribbons are investigated with the density functional theory; they reveal three stable geometric structures. The first type is a tubular structure formed by the covalent bonds of decorating boron or nitrogen atoms. The second one consists of curved nanoribbons created by the dipole-dipole interactions between two edges when decorated with Be, Mg, or Al atoms. The final structure is a flat nanoribbon produced due to the repulsive force between two edges; most decorated structures belong to this type. Various decorating atoms, different curvature angles, and the zigzag edge structure are reflected in the electronic properties, magnetic properties, and bonding configurations. Most of the resulting structures are conductors with relatively high free carrier densities, whereas a few are semiconductors due to the zigzag-edge-induced anti-ferromagnetism. PMID:25123103

  20. Advances in Convex Optimization

    Microsoft Academic Search

    S. Boyd; L. Vandenberghe; M. Grant

    2006-01-01

    In this talk I will give an overview of general convex optimization, which can be thought of as an extension of linear programming, and some recently developed subfamilies such as second-order cone, semidefinite, and geometric programming. Like linear programming, we have a fairly complete duality theory, and very effective numerical methods for these problem classes; in addition, recently developed software

  1. Continuing Conversation about Continuing Bonds

    ERIC Educational Resources Information Center

    Klass, Dennis

    2006-01-01

    The article is a response to the contributions the special issue of Death Studies on continuing bonds. The contributions indicate that the conversation among scholars has clarified our thinking on how bonds function in individual grief. The author discussed two issues to help keep the conversation moving: (a) the relationship of continuing bonds

  2. Cyclic Bonds in Branched Polymers

    E-print Network

    Kazumi Suematsu

    2015-02-19

    In the gelation theory it has been implicitly assumed that (I) a cyclic bond is a finite bond that returns to itself; (II) cyclic bonds distribute at random in network structures. In this paper these two assumptions are reexamined from a new point of view. The physical soundness of the assumptions are assessed through comparison with experimental observations.

  3. Coulombic Models in Chemical Bonding.

    ERIC Educational Resources Information Center

    Sacks, Lawrence J.

    1986-01-01

    Compares the coulumbic point charge model for hydrogen chloride with the valence bond model. It is not possible to assign either a nonpolar or ionic canonical form of the valence bond model, while the covalent-ionic bond distribution does conform to the point charge model. (JM)

  4. Low temperature gold wire bonding

    Microsoft Academic Search

    Y. M. Cheung; S. W; S. Ching

    1999-01-01

    We demonstrated that the bonding of gold wires for COB application was feasible at temperatures ~100°C or below by using a wedge bonder with a high frequency ultrasonic transducer (~138 kHz). An automatic rotary bondhead wedge bonder equipped with the transducer was employed to perform wire bonding. Bonding of gold wires was conducted on the aluminum pads of a test

  5. 46 CFR Sec. 10 - Bonds.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 10 Bonds...payment bonds required by Article 14 of the NSA-LUMPSUMREP Contract. The stand- ard...payment bond requirements of Article 14 of the NSA-LUMPSUMREP Contract, the...

  6. 46 CFR Sec. 10 - Bonds.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 10 Bonds...payment bonds required by Article 14 of the NSA-LUMPSUMREP Contract. The stand- ard...payment bond requirements of Article 14 of the NSA-LUMPSUMREP Contract, the...

  7. 46 CFR Sec. 10 - Bonds.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 10 Bonds...payment bonds required by Article 14 of the NSA-LUMPSUMREP Contract. The stand- ard...payment bond requirements of Article 14 of the NSA-LUMPSUMREP Contract, the...

  8. BONDING PROCEDURES MUNICIPAL STREETS SEMINAR

    E-print Network

    BONDING PROCEDURES MUNICIPAL STREETS SEMINAR Ahlers & Cooney, P.C. Mark Cory & Minniette Bucklin Association, Polk County and Iowa Bar Associations and the National Association of Bond Lawyers. Mr. Cory has of governmental bonds, but she also advises clients with respect to issues involving economic development

  9. The Bass trace conjecture Geometric version complexes

    E-print Network

    Berrick, A J.

    The Bass trace conjecture Progress Geometric version ­ complexes Geometric version ­ manifolds of manifolds #12;The Bass trace conjecture Progress Geometric version ­ complexes Geometric version ­ manifolds Applications Traces Hattori-Stallings trace (1965) First, explain Conjecture (Bass 1976) For any group G

  10. Low temperature reactive bonding

    DOEpatents

    Makowiecki, Daniel M. (Livermore, CA); Bionta, Richard M. (Livermore, CA)

    1995-01-01

    The joining technique requires no external heat source and generates very little heat during joining. It involves the reaction of thin multilayered films deposited on faying surfaces to create a stable compound that functions as an intermediate or braze material in order to create a high strength bond. While high temperatures are reached in the reaction of the multilayer film, very little heat is generated because the films are very thin. It is essentially a room temperature joining process.

  11. Disulfide bonds of acetylcholinesterase

    SciTech Connect

    MacPhee-Quigley, K.; Vedvick, T.; Taylor, P.; Taylor, S.

    1986-05-01

    The positions of the inter- and intrasubunit disulfide bridges were established for the 11S form of acetylcholinesterase (AChE) isolated from Torpedo californica. A major form of AChE localized within the basal lamina of the synapse is a dimensionally asymmetric molecule which contains either two (13S) or three (17S) sets of catalytic subunits linked to collagenous and non-collagenous structural subunits. Limited proteolysis yields a tetramer of catalytic subunits which sediments at 11S. Each catalytic subunit contains 8 cysteine residues. Initially, these Cys residues were identified following trypsin digestion of the reduced protein alkylated with (/sup 14/C)-iodoacetate. Peptides were resolved by gel filtration followed by reverse phase HPLC. To determine the disulfide bonding profile, native non-reduced 11S AChE was treated with a fluorescent, sulfhydryl-specific reagent, monobromobimane, prior to proteolytic digestion. One fluorescent Cys peptide was identified indicating that a single sulfhydryl residue was present in its reduced form. Three pairs of disulfide bonded peptides were identified, sequenced, and localized in the polypeptide chain. The Cys residue that is located in the C-terminal tryptic peptide was disulfide bonded to an identical peptide and thus forms the intersubunit crosslink. Finally, the cysteine positions have been compared with the sequence of the homologous protein, thyroglobulin. Both likely share a common pattern of folding.

  12. Global-Local Finite Element Analysis for Thermo-Mechanical Stresses in Bonded Joints

    NASA Technical Reports Server (NTRS)

    Shkarayev, S.; Madenci, Erdogan; Camarda, C. J.

    1997-01-01

    An analysis of adhesively bonded joints using conventional finite elements does not capture the singular behavior of the stress field in regions where two or three dissimilar materials form a junction with or without free edges. However, these regions are characteristic of the bonded joints and are prone to failure initiation. This study presents a method to capture the singular stress field arising from the geometric and material discontinuities in bonded composites. It is achieved by coupling the local (conventional) elements with global (special) elements whose interpolation functions are constructed from the asymptotic solution.

  13. Random broadcast on random geometric graphs

    SciTech Connect

    Bradonjic, Milan [Los Alamos National Laboratory; Elsasser, Robert [UNIV OF PADERBORN; Friedrich, Tobias [ICSI/BERKELEY; Sauerwald, Tomas [ICSI/BERKELEY

    2009-01-01

    In this work, we consider the random broadcast time on random geometric graphs (RGGs). The classic random broadcast model, also known as push algorithm, is defined as: starting with one informed node, in each succeeding round every informed node chooses one of its neighbors uniformly at random and informs it. We consider the random broadcast time on RGGs, when with high probability: (i) RGG is connected, (ii) when there exists the giant component in RGG. We show that the random broadcast time is bounded by {Omicron}({radical} n + diam(component)), where diam(component) is a diameter of the entire graph, or the giant component, for the regimes (i), or (ii), respectively. In other words, for both regimes, we derive the broadcast time to be {Theta}(diam(G)), which is asymptotically optimal.

  14. Monolithic Geometric Anti-Spring Blade

    E-print Network

    G. Cella; V. Sannibale; R. DeSalvo; S Márka; A. Takamori

    2004-06-23

    In this article we investigate the principle and properties of a vertical passive seismic noise attenuator conceived for ground based gravitational wave interferometers. This mechanical attenuator based on a particular geometry of cantilever blades called monolithic geometric anti springs (MGAS) permits the design of mechanical harmonic oscillators with very low resonant frequency (below 100mHz). Here we address the theoretical description of the mechanical device, focusing on the most important quantities for the low frequency regime, on the distribution of internal stresses, and on the thermal stability. In order to obtain physical insight of the attenuator peculiarities, we devise some simplified models, rather than use the brute force of finite element analysis. Those models have been used to optimize the design of a seismic attenuation system prototype for LIGO advanced configurations and for the next generation of the TAMA interferometer.

  15. Gear optimization

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    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.

  16. Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach

    PubMed Central

    Arrieta, Jorge; Cartwright, Julyan H. E.; Gouillart, Emmanuelle; Piro, Nicolas; Piro, Oreste; Tuval, Idan

    2015-01-01

    Mixing fluid in a container at low Reynolds number— in an inertialess environment—is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the “belly phase,” peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing. PMID:26154384

  17. Diffusion bonding of the oxide dispersion strengthened steel PM2000

    NASA Astrophysics Data System (ADS)

    Sittel, Wiebke; Basuki, Widodo W.; Aktaa, Jarir

    2013-11-01

    Ferritic oxide dispersion strengthened (ODS) steels are well suited as structural materials, e.g. for claddings in fission reactors and for plasma facing components in fusion power plants due to their high mechanical and oxidation stability at high temperatures and their high irradiation resistance. PM2000 is an iron based ODS ferritic steel with homogeneously distributed nanometric yttria particles. Melting joining techniques are not suitable for such ODS materials because of the precipitation and agglomeration of the oxide particles and hence the loss of their strengthening effect. Solid state diffusion bonding is thus chosen to join PM2000 and is investigated in this work with a focus on oxide particles. The diffusion bonding process is aided by the computational modeling, including the influence of the ODS particles. For modeling the microstructure stability and the creep behavior of PM2000 at various, diffusion bonding relevant temperatures (50-80% Tm) are investigated. Particle distribution (TEM), strength (tensile test) and toughness (Charpy impact test) obtained at temperatures relevant for bonding serve as input for the prediction of optimal diffusion bonding parameters. The optimally bonded specimens show comparable strength and toughness relative to the base material.

  18. 77 FR 32128 - Cancellation of Bond Subject to Enhanced Bonding Requirements Upon CBP's Acceptance of Qualified...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-31

    ...Cancellation of Bond Subject to Enhanced Bonding Requirements Upon CBP's Acceptance of...amount was calculated pursuant to enhanced bonding requirements (EBR bond) upon the agency's...INFORMATION: Background I. Enhanced Bonding Requirements In 2004, U.S....

  19. p Version nonlinear analysis of RC beams and slabs strengthened with externally bonded plates

    Microsoft Academic Search

    J. S. Ahn; K. S. Woo; P. K. Basu; J. H. Park

    2006-01-01

    The p-version nonlinear RC finite element model has been used to analyze the nonlinear behavior of RC beams and slabs as well as RC beams and slabs strengthened by externally bonded steel or FRP plates. The numerical approach is based on the p-version shell element, including the theory of anisotropic laminated composites considering geometric and material nonlinearities. In the nonlinear

  20. On the bond graphs in the Delaunay-tetrahedra of the simplicial decomposition of spatial protein

    E-print Network

    Grolmusz, Vince

    On the bond graphs in the Delaunay-tetrahedra of the simplicial decomposition of spatial protein atoms of the protein structures in the PDB, and analyzed geometrical properties of the tetrahedra of the points are on the surface of a sphere), then all regions are tetrahedra (cf. Figure 1). We are interested

  1. Bond Inspection by Impact Test

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Xiang, D.; Qin, Y.; Li, F.; Coulter, R. V.

    2010-02-01

    Kissing bond detection has been a challenging issue for NDE of bonded structures in aeronautical industry. A novel impact test technique for bond inspection has been developed, which shows great potential for kissing bond detection. The impact test employs a solenoid to produce impact forces in a bonded structure, and the induced elastic wave in the structure was picked up by an EMAT sensor, which located side by side with the solenoid. Both solenoid and EMAT sensor are integrated into a tap header that is mounted onto an automatic 2-D scanner to realize an automatic 2-D scanning. Multiple samples with artificial defects including kissing bonds and disbonds were used to test the impact test technique. The results show that those bond defects in the samples can be detected by the developed impact test technique. For comparison purpose, those samples were also tested with traditional ultrasonic C-scan.

  2. Mathematical Optimization

    NSDL National Science Digital Library

    Leske, Cavin.

    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.

  3. Effect of quantum nuclear motion on hydrogen bonding.

    PubMed

    McKenzie, Ross H; Bekker, Christiaan; Athokpam, Bijyalaxmi; Ramesh, Sai G

    2014-05-01

    This work considers how the properties of hydrogen bonded complexes, X-H?Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O-H?O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4-3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X-H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends. PMID:24811647

  4. Geometric phase in Stückelberg interferometry

    NASA Astrophysics Data System (ADS)

    Lim, Lih-King; Fuchs, Jean-Noël; Montambaux, Gilles

    2015-04-01

    We study the time evolution of a two-dimensional quantum particle exhibiting a two-band energy spectrum with two Dirac cones as, for example, in the honeycomb lattice. A force is applied such that the particle experiences two Landau-Zener transitions in succession in the vicinity of the Dirac cones. The adiabatic evolution between the two transitions leads to Stückelberg interferences, due to two possible trajectories in energy-momentum space. In addition to well-known dynamical and Stokes phases, the interference pattern reveals a geometric phase which depends on the chirality (winding number) and the mass sign associated with each Dirac cone, as well as on the type of trajectory (parallel or diagonal with respect to the two cones) in parameter space. This geometric phase reveals the coupling between the bands encoded in the structure of the wave functions. Stückelberg interferometry therefore appears as a way to access both intra- and interband geometric information.

  5. Geometrical and FEA study on Millipede Forming

    NASA Astrophysics Data System (ADS)

    Kong, Lingran; Tang, Di; Ding, Shichao; Zhang, Yuankun

    2013-12-01

    Millipede Forming is an innovative sheet metal forming approach that has been proposed and developed in Australia. U-channels, Z-channels or tubular products can be made by Millipede Forming. While a strip moves through an optimal transitional surface between the entry to exit of a forming stand, the redundant longitudinal membrane strain can be significantly reduced compared to the conventional roll forming, which is the essential principle to obtaining high quality products. The incremental forming process studied has demonstrated major advantages on space efficiency, power consumption and materials sensitivities. The purpose of this study is to investigate the effects of main geometrical parameters and their optimization, in order to minimize the redundant longitudinal strains into elastic to avoid the redundant plastic deformations at flange during forming. In this study, a mild-steel U-channel sample with 10 mm flange width, fabricated by Millipede Forming in a forming length of 200 mm has been studied. Theoretical longitudinal membrane strains at profile's edge of different transitional surfaces and downhill pass are also analyzed. The results showed that obtaining an optimal transitional surface is essential and necessary in controlling the peak longitudinal strain to an acceptable amount and that by increasing downhill pass, longitudinal strain can be significantly reduced. The optimized transitional surface and downhill pass flow were simulated by Abaqus, and the peak longitudinal strain was finally less than 0.2% through a very short forming length of 200 mm. The results prove that Millipede Forming can achieve a better product quality in a much shorter forming distance than conventional roll forming.

  6. Geometric parameter inverse model for drawbeads based on grey relational analysis and GA-BP

    NASA Astrophysics Data System (ADS)

    Xie, Yanmin

    2013-12-01

    In sheet metal forming, the wrinkling and fracture can be eliminated via an appropriate drawbead design. Proper drawbead design method to reduce time and cost is highly required. In the paper, the geometric parameters influencing semi-circular drawbead force are firstly analyzed making use of grey relational analysis, and the main parameters are obtained. The main parameters are sampled making use of Latin hypercube. The box forming is simulated with DYNAFORM, and the sample data are obtained. In the back propagation (BP) neural network, the thinning, thickening and major strains are selected as input parameters, and drawbead geometric parameters are selected as output objective. The inverse model of drawbead geometric parameters is established. The BP neural network weights are optimized with genetic algorithm (GA). Compared with the predictive values by BP, the parameters values by GA-BP are more accurate. Based on the GA-BP, the nonlinear relationship of the forming quality and drawbead geometric parameters is obtained making use of the optimized BP weights. Finally the optimum geometric parameters of drawbeads are obtained based on GA. The numerical simulations of box forming are compared before optimization and after optimization. The results show the optimized drawbeads can greatly improve the formability of sheet metal forming.

  7. Theoretical Aspects of the Biological Catch Bond

    Microsoft Academic Search

    Oleg V. Prezhdo; Yuriy V. Pereverzev

    2009-01-01

    he biological catch bond is fascinating and counterintuitive. When an external force is applied to a catch bond, either in vivo or in vitro, the bond resists breaking and becomes stronger instead. In contrast, ordinary slip bonds, which represent the vast majority of biological and chemical bonds, dissociate faster when subjected to a force. Catch-bond behavior was first predicted theoretically

  8. Does Geometric Coupling Generates Resonances?

    E-print Network

    I. C. Jardim; G. Alencar; R. R. Landim; R. N. Costa Filho

    2015-05-08

    Geometrical coupling in a co-dimensional one Randall-Sundrum scenario (RS) is used to study resonances of $p-$form fields. The resonances are calculated using the transfer matrix method. The model studied consider the standard RS with delta-like branes, and branes generated by kinks and domain-wall as well. The parameters are changed to control the thickness of the smooth brane. With this a very interesting pattern is found for the resonances. The geometrical coupling does not generate resonances for the reduced $p-$form in all cases considered.

  9. Geometric pumping in autophoretic channels

    E-print Network

    Sebastien Michelin; Thomas D. Montenegro Johnson; Gabriele De Canio; Nicolas Lobato-Dauzier; Eric Lauga

    2015-05-07

    Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.

  10. Geometric pumping in autophoretic channels

    E-print Network

    Michelin, Sebastien; De Canio, Gabriele; Lobato-Dauzier, Nicolas; Lauga, Eric

    2015-01-01

    Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.

  11. Geometric source separation: merging convolutive source separation with geometric beamforming

    Microsoft Academic Search

    Lucas C. Parra; Christopher V. Alvino

    2002-01-01

    Convolutive blind source separation and adaptive beamforming have a similar goal—extracting a source of interest (or multiple sources) while reducing undesired interferences. A benefit of source separation is that it overcomes the conventional cross-talk or leakage problem of adaptive beamforming. Beam- forming on the other hand exploits geometric information which is often readily available but not utilized in blind algorithms.

  12. Low temperature reactive bonding

    DOEpatents

    Makowiecki, D.M.; Bionta, R.M.

    1995-01-17

    The joining technique is disclosed that requires no external heat source and generates very little heat during joining. It involves the reaction of thin multilayered films deposited on faying surfaces to create a stable compound that functions as an intermediate or braze material in order to create a high strength bond. While high temperatures are reached in the reaction of the multilayer film, very little heat is generated because the films are very thin. It is essentially a room temperature joining process. 5 figures.

  13. Plasma cleaning on bond pad surfaces for gold wire bonding

    Microsoft Academic Search

    Wu-Hu Li; Klaus Reingruber; Norbert Mais; Albert Acuesta; Christian Alde Yape

    2009-01-01

    Ar plasma was employed to remove\\/reduce the oxidation of two typical types of bond pad surfaces, namely aluminum (Al) surface and gold (Au)-coated palladium (Pd) surface, prior to Au wire-bonding process. Field emission scanning electron microscopy (FESEM) and Auger electron spectroscopy (AES) were employed to characterize the bond pad surfaces without and with the plasma cleaning. Processability and reliability results

  14. Geometric and Electronic Structures of Manganese-substituted Iron Superoxide Dismutase

    PubMed Central

    Jackson, Timothy A.; Gutman, Craig T.; Maliekal, James; Miller, Anne-Frances; Brunold, Thomas C.

    2013-01-01

    The active-site structures of the oxidized and reduced forms of manganese-substituted iron superoxide dismutase (Mn(Fe)SOD) are examined, for the first time, using a combination of spectroscopic and computational methods. On the basis of electronic absorption, circular dichrosim (CD), magnetic CD (MCD), and variable-temperature variable-field MCD data obtained for oxidized Mn(Fe)SOD, we propose that the active site of this species is virtually identical to that of wild-type manganese SOD (MnSOD), both containing a metal ion that resides in a trigonal bipyramidal ligand environment. This proposal is corroborated by quantum mechanical / molecular mechanical (QM/MM) computations performed on complete protein models of Mn(Fe)SOD in both its oxidized and reduced states and, for comparison, wild-type (WT) MnSOD. The major differences between the QM/MM optimized active sites of WT MnSOD and Mn(Fe)SOD are a smaller (His)N–Mn–N(His) equatorial angle and a longer (Gln146(69))NH?O(sol) H-bond distance in the metal-substituted protein. Importantly, these modest geometric differences are consistent with our spectroscopic data obtained for the oxidized proteins and high-field electron paramagnetic resonance spectra reported previously for reduced Mn(Fe)SOD and MnSOD. As Mn(Fe)SOD exhibits a reduction midpoint potential (Em) almost 700 mV higher than that of MnSOD, which has been shown to be sufficient for explaining the lack of SOD activity displayed by the metal-subtituted species (Vance, C. K.; Miller, A. F. Biochemistry 2001, 40, 13079–13087), Ems were computed for our experimentally validated QM/MM optimized models of Mn(Fe)SOD and MnSOD. These computations properly reproduce the experimental trend and reveal that the drastically elevated Em of the metal substituted protein stems from a larger separation between the second-sphere Gln residue and the coordinated solvent in Mn(Fe)SOD relative to MnSOD, which causes a weakening of the corresponding H-bond interaction in the oxidized state and alleviates steric crowding in the reduced state. PMID:23461587

  15. Solder extrusion pressure bonding process and bonded products produced thereby

    DOEpatents

    Beavis, Leonard C. (Albuquerque, NM); Karnowsky, Maurice M. (Albuquerque, NM); Yost, Frederick G. (Ceder Crest, NM)

    1992-01-01

    Production of soldered joints which are highly reliable and capable of surviving 10,000 thermal cycles between about -40.degree. C. and 110.degree. C. Process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat and up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

  16. Solder extrusion pressure bonding process and bonded products produced thereby

    DOEpatents

    Beavis, L.C.; Karnowsky, M.M.; Yost, F.G.

    1992-06-16

    Disclosed is a process for production of soldered joints which are highly reliable and capable of surviving 10,000 thermal cycles between about [minus]40 C and 110 C. Process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat and up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

  17. An analytical model to determine the stress singularity and critical bonding angle for an elastic-viscoelastic bonded joint

    NASA Astrophysics Data System (ADS)

    Chowdhuri, M. A. K.; Xia, Z.

    2012-08-01

    Measurements of interface bonding strengths are necessary for predicting the failure behavior of structures and materials with bi-material interfaces. However, it is well known that due to the discontinuity of material properties, stress singularity may exist at the edges of the interface. For accurate determination of the bonding strength of bi-material interface, the elimination of the stress singularity is necessary. This paper presents an analytical solution for the determination of the stress singularity and the critical bonding angle of a bonded joint between elastic and viscoelastic materials. This solution is based on the analytical solution available for an elastic-elastic bonded joint via the elastic-viscoelastic corresponding principle. For the viscoelastic material, both time-independent and time-dependent Poisson's ratios are considered to find its effect on the stress singularity. As an example, the developed solution is applied to a simulated aluminum-epoxy bonded joint with a spherical interface. It is found that the critical bonding angle and the order of the stress singularity are different for assuming a time-independent or time-dependent Poisson's ratio of the idealized viscoelastic epoxy. With the analytical solution developed, it is possible to design an optimal interface geometry that can eliminate the stress singularity from the interface corner.

  18. Structural and vibrational spectroscopic studies on charge transfer and ionic hydrogen bonding interactions of melaminium benzoate dihydrate

    NASA Astrophysics Data System (ADS)

    Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Gunasekaran, S.; Rajakumar, P. R.; Anbalagan, G.

    2015-06-01

    Single crystals of melaminium benzoate dihydrate (MBDH) have been grown from aqueous solution by the slow solvent evaporation method at room temperature. Crystalline nature of the grown crystal has been confirmed by X-ray powder diffraction studies. The optimized geometry, frequency and intensity of the vibrational bands of MBDH were obtained by the Hartree-Fock and density functional theory using B3LYP/cam-B3LYP with 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with the experimental FT-IR and FT-Raman spectral values. The obtained vibrational wavenumbers and optimized geometric parameters are found to be in good agreement with the experimental data. UV-Visible spectrum was recorded in the region 200-400 nm and the electronic properties, HOMO-LUMO energies and other related electronic parameters are calculated. The isotropic chemical shifts computed by 1H and 13C NMR analysis also show good agreement with experimental observation. Natural bond orbital (NBO) analysis has been performed on MBDH compound to analyze the stability of the molecule arising from hyperconjugative interactions and charge delocalization. Molecular electrostatic potential surface (MEP) has also been performed by DFT/cam-B3LYP method with 6-311++G(d,p) basis set. Differential scanning calorimetric measurements performed on the powder sample indicate the phase transition point approximately at 368 and 358 K for heating and cooling, respectively.

  19. Exclusive selectivity in the one-pot formation of C-C and C-Se bonds involving Ni-catalyzed alkyne hydroselenation: optimization of the synthetic procedure and a mechanistic study.

    PubMed

    Orlov, Nikolay V; Chistyakov, Igor V; Khemchyan, Levon L; Ananikov, Valentine P; Beletskaya, Irina P; Starikova, Zoya A

    2014-12-19

    A unique Ni-catalyzed transformation is reported for the one-pot highly selective synthesis of previously unknown monoseleno-substituted 1,3-dienes starting from easily available terminal alkynes and benzeneselenol. The combination of a readily available catalyst precursor, Ni(acac)2, and an appropriately tuned phosphine ligand, PPh2Cy, resulted in the exclusive assembly of the s-gauche diene skeleton via the selective formation of C-C and C-Se bonds. The unusual diene products were stable under regular experimental conditions, and the products maintained the s-gauche geometry both in the solid state and in solution, as confirmed by X-ray analysis and NMR spectroscopy. Thorough mechanistic studies using ESI-MS revealed the key Ni-containing species involved in the reaction. PMID:25288369

  20. Sulfur K-Edge XAS and DFT Calculations on Nitrile Hydratase: Geometric and Electronic Structure of the Non-heme Iron Active Site

    PubMed Central

    Dey, Abhishek; Chow, Marina; Taniguchi, Kayoko; Lugo-Mas, Priscilla; Davin, Steven; Maeda, Mizuo

    2015-01-01

    The geometric and electronic structure of the active site of the non-heme iron enzyme nitrile hydratase (NHase) is studied using sulfur K-edge XAS and DFT calculations. Using thiolate (RS?)-, sulfenate (RSO?)-, and sulfinate (RSO2?)-ligated model complexes to provide benchmark spectral parameters, the results show that the S K-edge XAS is sensitive to the oxidation state of S-containing ligands and that the spectrum of the RSO? species changes upon protonation as the S–O bond is elongated (by ~0.1 Å). These signature features are used to identify the three cysteine residues coordinated to the low-spin FeIII in the active site of NHase as CysS?, CysSOH, and CysSO2? both in the NO-bound inactive form and in the photolyzed active form. These results are correlated to geometry-optimized DFT calculations. The pre-edge region of the X-ray absorption spectrum is sensitive to the Zeff of the Fe and reveals that the Fe in [FeNO]6 NHase species has a Zeff very similar to that of its photolyzed FeIII counterpart. DFT calculations reveal that this results from the strong ? back-bonding into the ?* antibonding orbital of NO, which shifts significant charge from the formally t26 low-spin metal to the coordinated NO. PMID:16402841

  1. The source of chemical bonding.

    PubMed

    Needham, Paul

    2014-03-01

    Developments in the application of quantum mechanics to the understanding of the chemical bond are traced with a view to examining the evolving conception of the covalent bond. Beginning with the first quantum mechanical resolution of the apparent paradox in Lewis's conception of a shared electron pair bond by Heitler and London, the ensuing account takes up the challenge molecular orbital theory seemed to pose to the classical conception of the bond. We will see that the threat of delocalisation can be overstated, although it is questionable whether this should be seen as reinstating the issue of the existence of the chemical bond. More salient are some recent developments in a longstanding discussion of how to understand the causal aspects of the bonding interaction--the nature of the force involved in the covalent link--which are taken up in the latter part of the paper. PMID:24984444

  2. Geometric theory of meromorphic functions

    Microsoft Academic Search

    A. Eremenko

    This is a survey of results on the following problem. Let X be a simply connected Riemann surface spread over the Riemann sphere. How are the properties of the uniformizing function of this surface related to the geometric properties of the surface? Based on the lectures in U. Michigan in May 2006.

  3. Components of Geometric Analogy Solution.

    ERIC Educational Resources Information Center

    Mulholland, Timothy M.; And Others

    1980-01-01

    Adults' geometric analogy solution was investigated as a function of systematic variations in the information structure of items. Latency data from verification of true and false items were recorded. A model incorporating assumptions about the form of item representation, working memory factors, and processing components and strategies was…

  4. Algorithmic + Geometric characterization of CAR

    E-print Network

    Gill, Richard D.

    Algorithmic + Geometric characterization of CAR (Coarsening at Random) Richard Gill - Utrecht but independent) CCAR 3 door problem X=door with car behind Y=two doors still closed = {your first choice, other door left closed} 3 door problem X=door with car behind Y=(your first choice, other door left closed

  5. Platonic Symmetry and Geometric Thinking

    ERIC Educational Resources Information Center

    Zsombor-Murray, Paul

    2007-01-01

    Cubic symmetry is used to build the other four Platonic solids and some formalism from classical geometry is introduced. Initially, the approach is via geometric construction, e.g., the "golden ratio" is necessary to construct an icosahedron with pentagonal faces. Then conventional elementary vector algebra is used to extract quantitative…

  6. Geometrical Methods in Gauge Theory

    E-print Network

    Henrique de A. Gomes

    2006-10-25

    In this work we explore the geometrical interpretation of gauge theories through the formalism of fiber bundles. Moreover, we conduct an investigation in the topology of fiber bundles, providing a proof of the Classification Theorem. In the last chapter we present some applications, such as electromagnetism and generalized Kaluza-Klein Theory.

  7. The geometric oblateness of Uranus

    NASA Technical Reports Server (NTRS)

    Franklin, F. A.; Avis, C. C.; Colombo, G.; Shapiro, I. I.

    1980-01-01

    The paper considers photographs of Uranus obtained by the Stratoscope II balloon-borne telescope in 1970. These data have been redigitized and reanalyzed, and the geometric oblateness of Uranus was determined from the isophotes near the limb using an expression in terms of the equatorial and polar radii.

  8. Metastable vacua and geometric deformations

    E-print Network

    A. Amariti; D. Forcella; L. Girardello; A. Mariotti

    2009-01-16

    We study the geometric interpretation of metastable vacua for systems of D3 branes at non isolated toric deformable singularities. Using the L^{aba} examples, we investigate the relations between the field theoretic susy breaking and restoration and the complex deformations of the CY singularities.

  9. Geometric Quantum Noise of Spin

    NASA Astrophysics Data System (ADS)

    Shnirman, Alexander; Gefen, Yuval; Saha, Arijit; Burmistrov, Igor S.; Kiselev, Mikhail N.; Altland, Alexander

    2015-05-01

    The presence of geometric phases is known to affect the dynamics of the systems involved. Here, we consider a quantum degree of freedom, moving in a dissipative environment, whose dynamics is described by a Langevin equation with quantum noise. We show that geometric phases enter the stochastic noise terms. Specifically, we consider small ferromagnetic particles (nanomagnets) or quantum dots close to Stoner instability, and investigate the dynamics of the total magnetization in the presence of tunneling coupling to the metallic leads. We generalize the Ambegaokar-Eckern-Schön effective action and the corresponding semiclassical equations of motion from the U(1) case of the charge degree of freedom to the SU(2) case of the magnetization. The Langevin forces (torques) in these equations are strongly influenced by the geometric phase. As a first but nontrivial application, we predict low temperature quantum diffusion of the magnetization on the Bloch sphere, which is governed by the geometric phase. We propose a protocol for experimental observation of this phenomenon.

  10. Celestial mechanics with geometric algebra

    NASA Technical Reports Server (NTRS)

    Hestenes, D.

    1983-01-01

    Geometric algebra is introduced as a general tool for Celestial Mechanics. A general method for handling finite rotations and rotational kinematics is presented. The constants of Kepler motion are derived and manipulated in a new way. A new spinor formulation of perturbation theory is developed.

  11. The geometric oblateness of Uranus

    NASA Astrophysics Data System (ADS)

    Franklin, F. A.; Avis, C. C.; Colombo, G.; Shapiro, I. I.

    1980-03-01

    The paper considers photographs of Uranus obtained by the Stratoscope II balloon-borne telescope in 1970. These data have been redigitized and reanalyzed, and the geometric oblateness of Uranus was determined from the isophotes near the limb using an expression in terms of the equatorial and polar radii.

  12. Geometric quantum noise of spin.

    PubMed

    Shnirman, Alexander; Gefen, Yuval; Saha, Arijit; Burmistrov, Igor S; Kiselev, Mikhail N; Altland, Alexander

    2015-05-01

    The presence of geometric phases is known to affect the dynamics of the systems involved. Here, we consider a quantum degree of freedom, moving in a dissipative environment, whose dynamics is described by a Langevin equation with quantum noise. We show that geometric phases enter the stochastic noise terms. Specifically, we consider small ferromagnetic particles (nanomagnets) or quantum dots close to Stoner instability, and investigate the dynamics of the total magnetization in the presence of tunneling coupling to the metallic leads. We generalize the Ambegaokar-Eckern-Schön effective action and the corresponding semiclassical equations of motion from the U(1) case of the charge degree of freedom to the SU(2) case of the magnetization. The Langevin forces (torques) in these equations are strongly influenced by the geometric phase. As a first but nontrivial application, we predict low temperature quantum diffusion of the magnetization on the Bloch sphere, which is governed by the geometric phase. We propose a protocol for experimental observation of this phenomenon. PMID:25978252

  13. VersaBond bone cement

    Microsoft Academic Search

    Tore Dalén; Kjell G. Nilsson

    2005-01-01

    VersaBond is a newly developed bone cement. To investigate its clinical performance, VersaBond was compared to Palacos R in a prospective randomized study in total knee replacement. Fifty-nine patients (61 knees) undergoing total knee replacement were randomized to either VersaBond or Palacos R bone cement and followed for 24 months using radiostereometric analysis (RSA).Up to 2 years there were no

  14. Beryllium and Strong Hydrogen Bonds

    Microsoft Academic Search

    T. Mark McCleskey; Brian L. Scott

    2009-01-01

    We compare beryllium to H and show that beryllium can displace H in many “strong hydrogen bonds” where Be as a “tetrahedral proton” (O-Be-O angle is tetrahedral as opposed to the nearly linear O-H—O angle) is thermodynamically preferred. The strong hydrogen bond provides two advantages. First, the O–X distance in a strong hydrogen bond is in the range 2.4–2.8 Å,

  15. 27 CFR 70.282 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Single bond in lieu of multiple bonds. 70...Occupational) Tax Bonds § 70.282 Single bond in lieu of multiple bonds. In the case of bonds required under this part, a single bond will not be accepted in lieu of...

  16. 27 CFR 70.282 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Single bond in lieu of multiple bonds. 70...Occupational) Tax Bonds § 70.282 Single bond in lieu of multiple bonds. In the case of bonds required under this part, a single bond will not be accepted in lieu of...

  17. 27 CFR 70.282 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2011-04-01 true Single bond in lieu of multiple bonds. 70...Occupational) Tax Bonds § 70.282 Single bond in lieu of multiple bonds. In the case of bonds required under this part, a single bond will not be accepted in lieu of...

  18. 27 CFR 70.282 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Single bond in lieu of multiple bonds. 70...Occupational) Tax Bonds § 70.282 Single bond in lieu of multiple bonds. In the case of bonds required under this part, a single bond will not be accepted in lieu of...

  19. Bonding and Structure of Intermetallics: A New Bond Order Potential

    Microsoft Academic Search

    D. G. Pettifor; M. Aoki; J. N. Murrell; A. Cottrell; A. M. Stoneham

    1991-01-01

    Intermetallics such as the transition metal aluminides present theorists with a challenge since bonding is not well described by currently available pair or embedded atom potentials. We show that a new angularly dependent, many-body potential for the bond order has all the necessary ingredients for an adequate description. In particular, by linearizing the moment-recursion coefficient relations, a cluster expansion is

  20. Bond pad surface quality for reliable wire bonding

    Microsoft Academic Search

    D. Martin Knotter; Ingrid A. Rink; Wim A. P. Claassen; Jos H. M. Philipsen

    The impact of fluoride and AlOx contaminants on the quality of wire bonding (Au to Al welding) has been measured. No or minor impact of these contaminants has been found with a standard ball shear test. Despite an accelerated lifetime test, the shear strength remains above the required specification limits. Intermetallic coverage, the percentage of the interface between the bond

  1. A wire scanning based method for geometric calibration of high resolution CT system

    NASA Astrophysics Data System (ADS)

    Jiang, Ruijie; Li, Guang; Gu, Ning; Chen, Gong; Luo, Shouhua

    2015-03-01

    This paper is about geometric calibration of the high resolution CT (Computed Tomography) system. Geometric calibration refers to the estimation of a set of parameters that describe the geometry of the CT system. Such parameters are so important that a little error of them will degrade the reconstruction images seriously, so more accurate geometric parameters are needed in the higher-resolution CT systems. But conventional calibration methods are not accurate enough for the current high resolution CT system whose resolution can reach sub-micrometer or even tens of nanometers. In this paper, we propose a new calibration method which has higher accuracy and it is based on the optimization theory. The superiority of this method is that we build a new cost function which sets up a relationship between the geometrical parameters and the binary reconstruction image of a thin wire. When the geometrical parameters are accurate, the cost function reaches its maximum value. In the experiment, we scanned a thin wire as the calibration data and a thin bamboo stick as the validation data to verify the correctness of the proposed method. Comparing with the image reconstructed with the geometric parameters calculated by using the conventional calibration method, the image reconstructed with the parameters calculated by our method has less geometric artifacts, so it can verify that our method can get more accurate geometric calibration parameters. Although we calculated only one geometric parameter in this paper, the geometric artifacts are still eliminated significantly. And this method can be easily generalized to all the geometrical parameters calibration in fan-beam or cone-beam CT systems.

  2. Geometric uncertainty relation for quantum ensembles

    NASA Astrophysics Data System (ADS)

    Heydari, Hoshang; Andersson, Ole

    2015-02-01

    Geometrical structures of quantum mechanics provide us with new insightful results about the nature of quantum theory. In this work we consider mixed quantum states represented by finite rank density operators. We review our geometrical framework that provide the space of density operators with Riemannian and symplectic structures, and we derive a geometric uncertainty relation for observables acting on mixed quantum states. We also give an example that visualizes the geometric uncertainty relation for spin-\\frac{1}{2} particles.

  3. Deformation and bonding processes in aluminum ultrasonic wire wedge bonding

    NASA Astrophysics Data System (ADS)

    Krzanowski, James E.; Murdeshwar, Nikhil

    1990-09-01

    The ultrasonic wire bonding (UWB) process has been examined using transmission electron microscopy (TEM) and standard wire pull testing techniques. Al-0.5 wt.% Mg wires 75 ?m in diameter were bonded to pure and alloyed Al substrates. The bonding parameters, surface roughness, and surface contamination levels were variables in the experiments. Cross-section TEM specimens were made from these samples. TEM analysis was conducted on the wire, wire/substrate interface and substrate. Pull tests showed that for the Al substrates the surface roughness or the presence of contamination did not effect the bond strength, whereas for contaminated stainless steel substrates, a three ?m surface finish resulted in the highest bond pull strength. The TEM observations revealed features such as low-angle grain boundaries, dislocation loops and the absence of a high dislocation density, indicating that the wire and substrate were dynamically annealed during bonding. Based on the width of a zone near a grain boundary in the wire which was depleted of dislocation loops, it was estimated that local heating equivalent to a temperature of 250° C for 90 msec was achieved in the wire during bonding. No evidence was found for melting along the bond interface, indicating that UWB is a solid-state process. Based on the TEM observations of the bond interface and the pull tests, it is concluded that the ultrasonic vibrations clean the surfaces to be joined to the extent that a good bond can be obtained by intimate metal-metal contact in the clean areas.

  4. Proton transfer and correlations between the CO, OH, NH and O?N bond lengths in amine phenolates

    Microsoft Academic Search

    I. Majerz; Z. Malarski; L. Sobczyk

    1997-01-01

    A relationship between the geometrical parameters of the O-H? N bridge based on the results of X-ray diffraction studies of a number of amine-phenol hydrogen-bonded complexes covering a broad ?p Ka range from ?3.91 to 5.93 are proposed. The analysis shows that the shortest bridges are realized when the proton transfer degree, reflected in the C-O bond length, reaches about

  5. Binding Pocket Optimization by Computational Protein Design

    PubMed Central

    Malisi, Christoph; Schumann, Marcel; Toussaint, Nora C.; Kageyama, Jorge; Kohlbacher, Oliver; Höcker, Birte

    2012-01-01

    Engineering specific interactions between proteins and small molecules is extremely useful for biological studies, as these interactions are essential for molecular recognition. Furthermore, many biotechnological applications are made possible by such an engineering approach, ranging from biosensors to the design of custom enzyme catalysts. Here, we present a novel method for the computational design of protein-small ligand binding named PocketOptimizer. The program can be used to modify protein binding pocket residues to improve or establish binding of a small molecule. It is a modular pipeline based on a number of customizable molecular modeling tools to predict mutations that alter the affinity of a target protein to its ligand. At its heart it uses a receptor-ligand scoring function to estimate the binding free energy between protein and ligand. We compiled a benchmark set that we used to systematically assess the performance of our method. It consists of proteins for which mutational variants with different binding affinities for their ligands and experimentally determined structures exist. Within this test set PocketOptimizer correctly predicts the mutant with the higher affinity in about 69% of the cases. A detailed analysis of the results reveals that the strengths of PocketOptimizer lie in the correct introduction of stabilizing hydrogen bonds to the ligand, as well as in the improved geometric complemetarity between ligand and binding pocket. Apart from the novel method for binding pocket design we also introduce a much needed benchmark data set for the comparison of affinities of mutant binding pockets, and that we use to asses programs for in silico design of ligand binding. PMID:23300688

  6. Binding pocket optimization by computational protein design.

    PubMed

    Malisi, Christoph; Schumann, Marcel; Toussaint, Nora C; Kageyama, Jorge; Kohlbacher, Oliver; Höcker, Birte

    2012-01-01

    Engineering specific interactions between proteins and small molecules is extremely useful for biological studies, as these interactions are essential for molecular recognition. Furthermore, many biotechnological applications are made possible by such an engineering approach, ranging from biosensors to the design of custom enzyme catalysts. Here, we present a novel method for the computational design of protein-small ligand binding named PocketOptimizer. The program can be used to modify protein binding pocket residues to improve or establish binding of a small molecule. It is a modular pipeline based on a number of customizable molecular modeling tools to predict mutations that alter the affinity of a target protein to its ligand. At its heart it uses a receptor-ligand scoring function to estimate the binding free energy between protein and ligand. We compiled a benchmark set that we used to systematically assess the performance of our method. It consists of proteins for which mutational variants with different binding affinities for their ligands and experimentally determined structures exist. Within this test set PocketOptimizer correctly predicts the mutant with the higher affinity in about 69% of the cases. A detailed analysis of the results reveals that the strengths of PocketOptimizer lie in the correct introduction of stabilizing hydrogen bonds to the ligand, as well as in the improved geometric complemetarity between ligand and binding pocket. Apart from the novel method for binding pocket design we also introduce a much needed benchmark data set for the comparison of affinities of mutant binding pockets, and that we use to asses programs for in silico design of ligand binding. PMID:23300688

  7. Geometrical Visualisation--Epistemic and Emotional

    ERIC Educational Resources Information Center

    Rodd, Melissa

    2010-01-01

    A well-documented experience of students of elementary Euclidean geometry is "seeing" a geometric result and being sure about its truth; this sort of experience gives rise to the notion of geometrical visualisation that is developed here. In this essay a philosophical argument for the epistemic potential of geometrical visualisation is reviewed,…

  8. The Arithmetic-Geometric Progression Abstract Domain

    E-print Network

    Feret, Jérôme

    VMCAI'05 The Arithmetic-Geometric Progression Abstract Domain Jérôme Feret École Normale Supérieure;Overview 1. Introduction 2. Case study 3. Arithmetic-geometric progressions 4. Benchmarks 5. Conclusion-geometric progressions 4. Benchmarks 5. Conclusion Jérôme Feret, LIENS 13 January, 2005 #12;Arithmetic

  9. Development of a Geometric Spatial Visualization Tool

    ERIC Educational Resources Information Center

    Ganesh, Bibi; Wilhelm, Jennifer; Sherrod, Sonya

    2009-01-01

    This paper documents the development of the Geometric Spatial Assessment. We detail the development of this instrument which was designed to identify middle school students' strategies and advancement in understanding of four geometric concept domains (geometric spatial visualization, spatial projection, cardinal directions, and periodic patterns)…

  10. Introduction to Pauli Geometric Algebra M. Berrondo

    E-print Network

    Hart, Gus

    Introduction to Pauli Geometric Algebra M. Berrondo May 9, 2009 #12;Pauli Algebra Geometric Algebras Geometric algebras (also called Cliord algebras) are used to endow physical spaces with a useful algebraic structure. By analyzing the physical system within this context, we can nd alternate

  11. Geometric Algebra and Physics Anthony Lasenby

    E-print Network

    Hart, Gus

    Geometric Algebra and Physics Anthony Lasenby Astrophysics Group, Cavendish Laboratory, Cambridge Microwave Background, and early universe Why am I here talking about `Geometric Algebra'? Came across effectively extends them to the relativistic domain And via `conformal geometric algebra' gives a whole new

  12. A wire bond reliability model

    Microsoft Academic Search

    T. L. Heleine; R. M. Murcko; S.-C. Wang

    1991-01-01

    A defect modeling approach is developed which allows the determination of the true failure rate with a minimal sample size. A model was developed using the proposed approach to estimate the failure rate of an aluminium\\/1% silicon wire ultrasonically bonded to aluminum and to gold pads. For this reliability model the variable was wire-bond width. Dependent upon the width of

  13. Failure Analysis of Wire Bonds

    Microsoft Academic Search

    Harry A. Schafft

    1973-01-01

    Failure analysis of wire bonds has an important part to play in determining the causes of microelectronic device failure and ways for making and using devices to achieve greater reliability. Several tests and procedures used in the failure analysis of wire bonds are reviewed. Some of the inferences. about possible causes of permanent or intermittent failure that can be drawn

  14. Thermoplastic polymeric adhesive for structural bonding applications for orthopaedic devices

    SciTech Connect

    Devanathan, D.; King, R.; Swarts, D.; Lin, S. [Zimmer, Inc., Warsaw, IN (United States); Ramani, K.; Tagle, J. [Purdue Univ., West Lafayette, IN (United States). Dept. of Mechanical Engineering

    1994-12-31

    The orthopaedics industry has witnessed tremendous growth in recent years primarily due to the introduction of high performance, porous coated implants. These devices have eliminated the need for the use of bone cement for in vivo implant fixation, replacing it with the ingrowth of bone into the porous surfaces. The metallurgical bonding processes used for attaching the porous to the implant body introduce some undesirable effect i.e., the reduction of the fatigue strength of the implant due to the ``notches`` created and also due to the high temperature exposure during the sintering operations. This paper describes the development of a thermoplastic polymeric adhesive based structural bonding technique. The high performance polymeric adhesive is fully characterized with respect to its intended application. The design of the porous layer is optimized to achieve a reliable bond to the implant. A thermal heating/cooling process was developed to control the final polymer morphology. Static and fatigue tests were conducted to fully characterize the adhesive bond strength. A ring shear test method was developed to determine the shear strength of the bond interface. Besides the characterization of the adhesive bond, the joints will be analyzed using finite element models. The correlation between the analytical models and the

  15. Bonding and Integration Technologies for Silicon Carbide Based Injector Components

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.; Singh, Mrityunjay

    2008-01-01

    Advanced ceramic bonding and integration technologies play a critical role in the fabrication and application of silicon carbide based components for a number of aerospace and ground based applications. One such application is a lean direct injector for a turbine engine to achieve low NOx emissions. Ceramic to ceramic diffusion bonding and ceramic to metal brazing technologies are being developed for this injector application. For the diffusion bonding, titanium interlayers (PVD and foils) were used to aid in the joining of silicon carbide (SiC) substrates. The influence of such variables as surface finish, interlayer thickness (10, 20, and 50 microns), processing time and temperature, and cooling rates were investigated. Microprobe analysis was used to identify the phases in the bonded region. For bonds that were not fully reacted an intermediate phase, Ti5Si3Cx, formed that is thermally incompatible in its thermal expansion and caused thermal stresses and cracking during the processing cool-down. Thinner titanium interlayers and/or longer processing times resulted in stable and compatible phases that did not contribute to microcracking and resulted in an optimized microstructure. Tensile tests on the joined materials resulted in strengths of 13-28 MPa depending on the SiC substrate material. Non-destructive evaluation using ultrasonic immersion showed well formed bonds. For the joining technology of brazing Kovar fuel tubes to silicon carbide, preliminary development of the joining approach has begun. Various technical issues and requirements for the injector application are addressed.

  16. Geometric Algebras for Euclidean Geometry

    E-print Network

    Charles Gunn

    2015-01-26

    The article explores the question, which form of geometric algebra is best-suited for doing euclidean geometry? It begins with a review of mathematical prerequisites, including quaternions and biquaternions, dual exterior algebra, and the Cayley-Klein construction. These ingredients are combined into the dual projectivized Clifford algebra $\\mathbf{P(\\mathbb{R}^*_{n,0,1})}$ (PGA), as a geometric algebra for euclidean geometry. Next, a set of fundamental terms which carry multiple meanings in the existing literature, including $\\mathit{homogeneous model}$, $\\mathbb{R}^{n}$, $\\mathit{euclidean}$, and $\\mathit{duality}$ are clarified. This leads to the conclusion that PGA deserves the title of $\\mathit{standard}$ homogeneous model of euclidean geometry. This is followed by a comparison with the the conformal model for euclidean geometry (CGA). It is shown that these two algebras exhibit the same formal feature set for this task. The article ends with a comparison based on practical considerations.

  17. The verdict geometric quality library.

    SciTech Connect

    Knupp, Patrick Michael; Ernst, C.D. (Elemental Technologies, Inc., American Fork, UT); Thompson, David C. (Sandia National Laboratories, Livermore, CA); Stimpson, C.J. (Elemental Technologies, Inc., American Fork, UT); Pebay, Philippe Pierre

    2006-03-01

    Verdict is a collection of subroutines for evaluating the geometric qualities of triangles, quadrilaterals, tetrahedra, and hexahedra using a variety of metrics. A metric is a real number assigned to one of these shapes depending on its particular vertex coordinates. These metrics are used to evaluate the input to finite element, finite volume, boundary element, and other types of solvers that approximate the solution to partial differential equations defined over regions of space. The geometric qualities of these regions is usually strongly tied to the accuracy these solvers are able to obtain in their approximations. The subroutines are written in C++ and have a simple C interface. Each metric may be evaluated individually or in combination. When multiple metrics are evaluated at once, they share common calculations to lower the cost of the evaluation.

  18. Geometrical modelling of textile reinforcements

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    The mechanical properties of textile composites are dictated by the arrangement of yarns contained within the material. Thus, to develop a comprehensive understanding of the performance of these materials, it is necessary to develop a geometrical model of the fabric structure. This task is quite complex, as the fabric is made from highly flexible yarn systems which experience a certain degree of compressibility. Furthermore there are tremendous forces acting on the fabric during densification typically resulting in yarn displacement and misorientation. The objective of this work is to develop a methodology for characterizing the geometry of yarns within a fabric structure including experimental techniques for evaluating these models. Furthermore, some applications of these geometric results to mechanical property predictions models are demonstrated.

  19. Bouncing Balls and Geometric Series

    NSDL National Science Digital Library

    Besson, Morgan

    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

  20. Social bonding: regulation by neuropeptides

    PubMed Central

    Lieberwirth, Claudia; Wang, Zuoxin

    2014-01-01

    Affiliative social relationships (e.g., among spouses, family members, and friends) play an essential role in human society. These relationships affect psychological, physiological, and behavioral functions. As positive and enduring bonds are critical for the overall well-being of humans, it is not surprising that considerable effort has been made to study the neurobiological mechanisms that underlie social bonding behaviors. The present review details the involvement of the nonapeptides, oxytocin (OT), and arginine vasopressin (AVP), in the regulation of social bonding in mammals including humans. In particular, we will discuss the role of OT and AVP in the formation of social bonds between partners of a mating pair as well as between parents and their offspring. Furthermore, the role of OT and AVP in the formation of interpersonal bonding involving trust is also discussed. PMID:25009457

  1. Simplicial Calculus with Geometric Algebra

    Microsoft Academic Search

    Garret Sobczyk

    We construct geometric calculus on an oriented k-surface embedded in Eu- clidean space by utilizing the notion of an oriented k-surface as the limit set of a sequence of k-chains. This method provides insight into the relationship between the vector derivative, and the Fundamental Theorem of Calculus and Residue Theorem It should be of practical value in numerical flnite difierence

  2. PALSAR Radiometric and Geometric Calibration

    Microsoft Academic Search

    Masanobu Shimada; Osamu Isoguchi; Takeo Tadono; Kazuo Isono

    2009-01-01

    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

  3. Equilibrium Pricing of Special Bearer Bonds

    Microsoft Academic Search

    Jayanth Rama Varma

    In 1981, the Government issued Special Bearer Bonds under a scheme which allowed people to invest their black money in these bonds and enjoy freedom from investigations and prosecutions for tax evasion in respect of their holdings of these bonds. Through these bonds are no longer available in tap, there is an active secondary market for these bonds; the complete

  4. hp calculators HP 50g Bond Price

    E-print Network

    Vetter, Frederick J.

    hp calculators HP 50g Bond Price The FINANCE menu Bond Price Practice solving for the price of a bond #12;hp calculators HP 50g Bond Price hp calculators - 2 - HP 50g Bond Price The FINANCE menu. To exit from this data entry screen, press the $ key. Figure 2 The HP 50g Financial solver follows

  5. hp calculators HP 50g Bond Yield

    E-print Network

    Vetter, Frederick J.

    hp calculators HP 50g Bond Yield The FINANCE menu Bond Yield Practice solving for the yield of a bond #12;hp calculators HP 50g Bond Yield hp calculators - 2 - HP 50g Bond Yield The FINANCE menu as Beg if chosen. To exit from this data entry screen, press the $ key. Figure 2 The HP 50g Financial

  6. Thermocompression bonding of alumina ceramics to metal

    Microsoft Academic Search

    S. Das; A. N. Tiwari; A. R. Kulkarni

    2004-01-01

    Alumina ceramics and Kovar with aluminum interlayer are pressed together under vacuum at temperatures around 600°C for joining. This process produces mechanically strong ceramic to metal bonds in one step in an economic manner. In order to arrive at the optimum conditions for solid-state bonding, effects of bonding temperature, pressure and time on the bond strength have been studied. Bonding

  7. Geometric programming prediction of design trends for OMV protective structures

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  8. Geometric aspects of particle segregation.

    PubMed

    Caulkin, R; Jia, X; Fairweather, M; Williams, R A

    2010-05-01

    Size segregation is a natural occurrence both in everyday life and in industrial processes. Understanding and research of the phenomenon has overwhelmingly been from a mechanistic point of view. This paper demonstrates through simulations that segregation can also be explained and trends predicted geometrically. The algorithm used in this study contains three simple elements: random walks combined with a rebounding probability to encourage particles to settle, plus the non-overlap constraint. It is implemented digitally in a regular lattice grid, to make it easy to deal with arbitrary shapes. It does not explicitly consider any particle interaction forces, and it does not include any rules specifically designed to promote or suppress segregation. Yet particle movement, which occurs within a digitized cubic grid, leads to shaking-induced segregation comparable to that observed in physical tests. The paper details the comparison of shaking-induced particle segregation between a series of computer based simulations and those of physical experiments undertaken in the laboratory. A range of mixtures, comprising nonspherical, arbitrary shaped/sized particles are investigated, having been packed into pseudo-two-dimensional containers. The simulation results suggest that segregation can be adequately explained, from a geometrical point of view, as a result of the relative motion between particles of different sizes and shapes. The geometrical algorithm thus provides a fast and qualitative prediction as to how likely segregation is to occur for any given mixture of arbitrary shapes. PMID:20866221

  9. Geometric Tachyon and Warm Inflation

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Anindita; Deshamukhya, Atri

    2013-03-01

    The inflationary models developed in presence of a background radiation can be a solution to the reheating problem faced by common cold (isentropic) inflationary scenario. A D-brane system comprising of k Neuvo-Schwarz (NS) 5-branes with a transverse circle and BPS D3-branes with world volume parallel to the NS 5-branes, placed at a point on the transverse circle diametrically to NS 5-brane has a point of unstable equilibrium and the D3-brane has a geometric tachyonic mode associated with displacement of the brane along the circle. Cold inflationary scenario has been studied in connection with this geometric tachyon [S. Panda, M. Sami and S. Tsujikawa, Phys. Rev. D73, 023515 (2006)] where it was found that one needs a background of minimum 104 branes to realize a viable inflationary model. In this piece of work, we have tried to study a model of inflation driven by this geometric tachyon in presence of radiation. We have found that compared to the isentropic scenario, to satisfy the observational bounds, the number of background branes required in this case reduces drastically and a viable model can be obtained with even six to seven NS 5-branes in the background. In this context, we have also analyzed the non-gaussianity associated with the model and observed that the concerned parameter lies well within the observation limit.

  10. Electronic and geometric structures of MoxSy and WxSy (

    Microsoft Academic Search

    S. Gemming; J. Tamuliene; G. Seifert; N. Bertram; Y. D. Kim; G. Ganteför

    2006-01-01

    Electronic and geometric structures of MxSy (M = W, Mo; x=1,2,4;y=1-12) clusters have been studied using density functional theory calculations, and compared to experimental photoelectron spectra. For the metal atoms, an uptake of up to six sulfur atoms has been observed, which can be explained by the bonding of S3 - chains. A structural difference to the corresponding oxides is

  11. Halogen bonding (X-bonding): A biological perspective

    PubMed Central

    Scholfield, Matthew R; Zanden, Crystal M Vander; Carter, Megan; Ho, P Shing

    2013-01-01

    The concept of the halogen bond (or X-bond) has become recognized as contributing significantly to the specificity in recognition of a large class of halogenated compounds. The interaction is most easily understood as primarily an electrostatically driven molecular interaction, where an electropositive crown, or ?-hole, serves as a Lewis acid to attract a variety of electron-rich Lewis bases, in analogous fashion to a classic hydrogen bonding (H-bond) interaction. We present here a broad overview of X-bonds from the perspective of a biologist who may not be familiar with this recently rediscovered class of interactions and, consequently, may be interested in how they can be applied as a highly directional and specific component of the molecular toolbox. This overview includes a discussion for where X-bonds are found in biomolecular structures, and how their structure–energy relationships are studied experimentally and modeled computationally. In total, our understanding of these basic concepts will allow X-bonds to be incorporated into strategies for the rational design of new halogenated inhibitors against biomolecular targets or toward molecular engineering of new biological-based materials. PMID:23225628

  12. 27 CFR 19.152 - Types of bonds.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...DEPARTMENT OF THE TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Bonding Requirements for A Dsp § 19.152 Types of bonds. (a) Basic Bonds. There are two basic types of bonds: the operations bond, and the...

  13. 27 CFR 19.152 - Types of bonds.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Bonding Requirements for A Dsp § 19.152 Types of bonds. (a) Basic Bonds. There are two basic types of bonds: the operations bond, and the...

  14. 27 CFR 19.152 - Types of bonds.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Bonding Requirements for A Dsp § 19.152 Types of bonds. (a) Basic Bonds. There are two basic types of bonds: the operations bond, and the...

  15. 27 CFR 19.152 - Types of bonds.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...DEPARTMENT OF THE TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Bonds and Consents of Surety Bonding Requirements for A Dsp § 19.152 Types of bonds. (a) Basic Bonds. There are two basic types of bonds: the operations bond, and the...

  16. 29 CFR 2580.412-19 - Term of the bond, discovery period, other bond clauses.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules § 2580...section 13, if, with respect to bonding coverage required under section...

  17. 29 CFR 2580.412-19 - Term of the bond, discovery period, other bond clauses.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...DEPARTMENT OF LABOR TEMPORARY BONDING RULES UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 TEMPORARY BONDING RULES General Bond Rules § 2580...section 13, if, with respect to bonding coverage required under section...

  18. Optimization of the geometry of the diphenylamine molecule by semiempirical quantum chemical methods

    SciTech Connect

    Pankratov, A.N.; Mushtakova, S.P.; Gribov, L.A.

    1986-03-01

    Available data on experimental study of the geometry of the diphenylamine molecule (I) in solution and in the crystal are fragmentary and not always reliable. Previously, they did a conformational analysis of molecule I using the atom-atom potential method. In order to refine the geometric parameters found for molecule I, optimization of its geometry is provided in the paper using the CNDO/2, INDO, MINDO/3 methods with the use of programs for the BESM-6 computer which are part of the VIKING program set. The angles of rotation for the phenyl rings relative to the CNC plane, the bond angles C/sub 2/N/sub 7/C/sub 8/ and C/sub 2/N/sub 7/H/sub 19/, and also the dihedral angle H/sub 19/N/sub 7/C/sub 8/C/sub 9/ were subjected to optimization. For any set of values for the indicated parameters, the bond angle C/sub 8/N/sub 7/H/sub 19/ is determined unambiguously. The results of the calculations are evidence that the MINDO/3 method is not suitable for optimization of the geometry for molecules of the indicated series; in particular, it leads to much too high a value for the CNC angles (135.9/sup 0/). The CNDO/2 method reproduces well the real value of the CNC angle (124.1/sup 0/) and confirms the known pyrimidal character of the nitrogen atom, the sum of the bond angles of which proved to be equal to 353.6/sup 0/. The calculation in the INDO approximation successfully gives the basic characteristics of the molecular geometry of (I); according to this approximation, the CNC angle is equal to 123.2/sup 0/, the CNH angles are equal to 118.0 and 118.8/sup 0/, the sum of the angles for the nitrogen atom is 360.0/sup 0/.

  19. Fabrication of nanoporous gold and the application for substrate bonding at low temperature

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Shan; Lin, Yu-Ching; Gessner, Thomas; Esashi, Masayoshi

    2015-03-01

    MEMS-compatible fabrication of nanoporous gold and the application for low temperature bonding are demonstrated. A cyanide-free electroplating solution is prepared for the Au–Sn alloy deposition. To investigate the influence of electroplating on Au–Sn alloy and nanoporous gold, different plating parameters and various sizes of patterns are designed and discussed. The optimized electroplating condition realizes 40 to 720 µm line width patterns fabricated on the same substrate. Low temperature substrate bonding at 200 °C is achieved with nanoporous gold and gold film, which has shear bond strength more than 60 MPa. The fracture inspection of the bonded area after shear tests verifies the bonding success. This study gives a study for fabricating on-chip nanostructure, and the results indicate the high feasibility of nanoporous gold for low temperature substrate bonding.

  20. Research on the Deformation Mechanism and Failure Behavior of Punch Bonding Technology with Dissimilar Sheet Metals

    NASA Astrophysics Data System (ADS)

    Li, Feng; Li, Jian Hui; Li, Chao; Wang, L. L.

    2012-05-01

    This article presents a study of the deformation mechanisms and failure behavior of punch bonding technology for dissimilar sheet metals. Using theoretical and numerical methods, the simulation of the punch bonding process is presented and the results show that to realize effective punch bonding, the sheets with higher elastic modulus and yield strength should be located at the punch side. It is also shown that when the boss height of the female die ( X 1) is too small, it is liable to induce excessive stress concentration under the punch blade, whereas when X 1 is too large, the embedded depth of the sheets and the bonding reliability decrease significantly. Punch bonding experiments were performed and the results showed that for the configuration tested an X 1 value of 10 mm was optimal for connection strength. The failure behavior of the punch bonding joint was joint cracking with smaller female die boss height and joint pull-off with larger female die boss height.

  1. Correlated Tunneling in Hydrogen Bonds

    NASA Astrophysics Data System (ADS)

    Lin, Lin; Morrone, Joseph A.; Car, Roberto

    2011-10-01

    We study the quantum nature of the protons participating in hydrogen bonds in several ice structures by analyzing the one particle density matrix. We find that in all cases, including ice Ih, the most common form of ice, and the high pressure phases, ice VIII, VII, and X, the system is ground-state dominated. However, while the dynamics is uncorrelated in the structures with standard asymmetric hydrogen bonds, such as ice Ih and VIII, local correlations among the protons characterize ice VII and, to a lesser extent, ice X in the so-called low barrier hydrogen bond regime. The correlations appear along the path to hydrogen bond symmetrization, when quantum fluctuations delocalize the proton on the two bond sides. The correlations derive from a strong requirement for local charge neutrality that favors concerted motion along the bonds. The resulting behavior deviates substantially from mean field theory, which would predict in ice VII coherent tunneling of the proton between the two bond sides, thereby causing an ionization catastrophe. Due to the correlations, the quantum state of the proton is entangled.

  2. 2 CFR 200.325 - Bonding requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bonding requirements. 200.325 Section 200... Procurement Standards § 200.325 Bonding requirements. For construction...or pass-through entity may accept the bonding policy and requirements of the...

  3. Cratering on thermosonic copper wire ball bonding

    NASA Astrophysics Data System (ADS)

    Wei, Tan Chee; Daud, Abdul Razak

    2002-06-01

    Copper wire bonding offers several mechanical and electrical advantages as well as cost saving compared to its gold wire predecessor. Despite these benefits, silicon cratering, which completes the fracture and removal of bond pad underlayers, has been a major hurdle to overcome in copper wire bonding. Copper wire is harder than gold, and thus needs greater ultrasonic power and bond force to bond it onto metal pads such as aluminum. This paper reports a study on the influence of wire materials, bond pad hardness, and bonding-machine parameters (i.e., ultrasonic power and bond force) on silicon cratering phenomenon. Ultrasonic power and z-axis bond force were identified as the most critical bonding machine parameters in silicon cratering defects. A combination of greater bond force and lower ultrasonic power avoids silicon cratering and gives the desired effects. Results also show that a harder bond pad provides relatively good protection from silicon cratering.

  4. 43 CFR 3904.10 - Bonding requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Interior 2 2014-10-01 2014-10-01 false Bonding requirements. 3904.10 Section 3904.10 Public Lands...MANAGEMENT-GENERAL Bonds and Trust Funds § 3904.10 Bonding requirements. (a) Prior to issuing a lease...

  5. 43 CFR 3904.10 - Bonding requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Interior 2 2012-10-01 2012-10-01 false Bonding requirements. 3904.10 Section 3904.10 Public Lands...MANAGEMENT-GENERAL Bonds and Trust Funds § 3904.10 Bonding requirements. (a) Prior to issuing a lease...

  6. 43 CFR 3904.10 - Bonding requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Interior 2 2013-10-01 2013-10-01 false Bonding requirements. 3904.10 Section 3904.10 Public Lands...MANAGEMENT-GENERAL Bonds and Trust Funds § 3904.10 Bonding requirements. (a) Prior to issuing a lease...

  7. 43 CFR 3904.10 - Bonding requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Interior 2 2011-10-01 2011-10-01 false Bonding requirements. 3904.10 Section 3904.10 Public Lands...MANAGEMENT-GENERAL Bonds and Trust Funds § 3904.10 Bonding requirements. (a) Prior to issuing a lease...

  8. 26 CFR 301.7102-1 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Single bond in lieu of multiple bonds. 301...ADMINISTRATION Bonds § 301.7102-1 Single bond in lieu of multiple bonds. (a...discretion of the district director, furnish a single bond in lieu of such two or more...

  9. 26 CFR 301.7102-1 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Single bond in lieu of multiple bonds. 301...ADMINISTRATION Bonds § 301.7102-1 Single bond in lieu of multiple bonds. (a...discretion of the district director, furnish a single bond in lieu of such two or more...

  10. 26 CFR 301.7102-1 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Single bond in lieu of multiple bonds. 301...ADMINISTRATION Bonds § 301.7102-1 Single bond in lieu of multiple bonds. (a...discretion of the district director, furnish a single bond in lieu of such two or more...

  11. 26 CFR 301.7102-1 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Single bond in lieu of multiple bonds. 301...ADMINISTRATION Bonds § 301.7102-1 Single bond in lieu of multiple bonds. (a...discretion of the district director, furnish a single bond in lieu of such two or more...

  12. 26 CFR 301.7102-1 - Single bond in lieu of multiple bonds.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Single bond in lieu of multiple bonds. 301...ADMINISTRATION Bonds § 301.7102-1 Single bond in lieu of multiple bonds. (a...discretion of the district director, furnish a single bond in lieu of such two or more...

  13. Influence of Bonding Parameters on the Reliability of Heavy Wire Bonds on Power Semiconductors

    Microsoft Academic Search

    Jens Goehre; Ute Geissler; Martin Schneider-Ramelow; Klaus-Dieter Lang

    2012-01-01

    In order to investigate the effect of the bonding parameters on the reliability of Al heavy wire bonds, samples were bonded with three different ultrasonic power levels and three different bonding force levels. The samples were exposed to active power cycling with a temperature swing of 120K (measured at the chip center). Each wire bond¿s individual temperature swing was determined

  14. Tensile Bond Strength of Latex-Modified Bonded Concrete Overlays

    NASA Astrophysics Data System (ADS)

    Dubois, Cameron; Ramseyer, Chris

    2010-10-01

    The tensile bond strength of bonded concrete overlays was tested using the in-situ pull-off method described in ASTM C 1583 with the goal of determining whether adding latex to the mix design increases bond strength. One slab of ductile concrete (f'c > 12,000 psi) was cast with one half tined, i.e. roughened, and one half steel-troweled, i.e. smooth. The slab surface was sectioned off and overlay mixtures containing different latex contents cast in each section. Partial cores were drilled perpendicular to the surface through the overlay into the substrate. A tensile loading device applied a direct tensile load to each specimen and the load was increased until failure occurred. The tensile bond strength was then calculated for comparison between the specimens.

  15. Alternative alloys for resin-bonded retainers.

    PubMed

    Lawson, J R

    1991-01-01

    Traditionally, resin-bonded fixed partial dentures have been made with nickel-chrome-beryllium alloys and cemented with conventional resin luting cements. However, alternative alloys for resin-bonded retainers offer improved physical and biocompatible properties, and resin-metal bond strengths twice that of traditional methods can be achieved. The superior bonds obtained with etched base metals bonded with adhesive resins and silica-coated alloys bonded with silane-coupling agents make these the most desirable techniques available. PMID:2033556

  16. Ultrasonic Imaging Of Bond Layers Through Bond Layers

    NASA Technical Reports Server (NTRS)

    Chern, E. James

    1992-01-01

    Combination of hardware and software helps ultrasonic C-scan inspection system create images of bond layer in laminated composite material, even when obscured by another bond layer. Produces image of both layers in single scan. Includes ultrasonic transducer, pulser/receiver, mechanical scanner, personal computer as controller, and electronic circuitry that gates first and second peak signals, detects peaks, and feeds resulting amplitude data to computer.

  17. Tunable infrared generation with diffusion-bonded-stacked gallium arsenide

    NASA Astrophysics Data System (ADS)

    Zheng, Dong

    Mid-infrared (MIR) radiation finds increasing applications in remote sensing, spectroscopy and military counter-measures. Nonlinear optical interactions provide one approach to tunable MIR sources generation. The development of MIR nonlinear optical crystals with excellent performance at a reasonable cost is essential for applications. Diffusion-bonded-stacked (DBS) GaAs periodic structures are a new family of quasi-phasematched (QPM) nonlinear optical crystals. The bonding process preserves the optical and mechanical properties of the bulk material, while the periodic modulation of the nonlinear coefficient permits QPM interactions. DBS GaAs bonding requirements, such as number of bonded layers and tolerable optical loss, are discussed. Nonlinear optical properties like mixing gain, wavelength, temperature and angular acceptance of the bonded structure, are predicted. DBS GaAs devices with up to 50 layers were bonded and characterized. Optical loss from interfacial voids and gaps at shorter wavelengths, from processing induced p- type free carrier absorption at longer wavelengths was characterized. 'Lithographic dicing' was invented and demonstrated as a replacement for mechanical dicing, resulting in the capability to handle thin wafers and cleaner interfaces for better bonding. Absorption due to semi-insulating-to-p-type conversion, a bulk crystal loss mechanism, was found to be induced by high bonding temperatures, and dependent on wafer sources and materials in contact with the stack. Optimized bonding parameters reduced the optical loss of 36-layer DBS GaAs to less than 0.2 cm-1 at long wavelengths. Tunable 15.6 to 17.6 ?m coherent radiation at 90-ps pulse width was generated by difference frequency mixing in a 24-layer DBS GaAs device. The wavelength tuning curve agreed with theoretical predictions demonstrating that the bonding process maintained nonlinear optical phasematching over the 6 mm interaction length. Maximum mixing gain of 0.7%, or 5% internal quantum gain, was measured at 16.6 ?m. Other DBS GaAs devices for frequency doubling of CO2 laser radiation and difference frequency mixing of various laser sources were demonstrated. Tunable MIR radiation from 4.7 ?m to 17.6 ?m was generated demonstrating feasibility of diffusion bonded structures to generate broadly tunable MIR wavelengths.

  18. SiO and GeO bonded interactions as inferred from the bond critical point properties of electron density distributions

    Microsoft Academic Search

    G. V. Gibbs; M. B. Boisen; F. C. Hill; O. Tamada; R. T. Downs

    1998-01-01

    The topological properties of the electron density distributions for more than 20 hydroxyacid, geometry optimized molecules with SiO and GeO bonds with 3-, 4-, 6- and 8-coordinate Si and Ge cations were calculated. Electronegativities calculated with the bond critical point (bcp) properties of the distributions indicate, for a given coordination number, that the electronegativity of Ge ( 1.85) is slightly

  19. SiO and GeO bonded interactions as inferred from the bond critical point properties of electron density distributions

    Microsoft Academic Search

    G. V. Gibbs; M. B. Boisen; F. C. Hill; O. Tamada; R. T. Downs

    1998-01-01

    The topological properties of the electron density distributions for more than 20 hydroxyacid, geometry optimized molecules\\u000a with SiO and GeO bonds with 3-, 4-, 6- and 8-coordinate Si and Ge cations were calculated. Electronegativities calculated\\u000a with the bond critical point (bcp) properties of the distributions indicate, for a given coordination number, that the electronegativity\\u000a of Ge (?1.85) is slightly larger

  20. Direct-bonded four-junction GaAs solar cells

    NASA Astrophysics Data System (ADS)

    Jingman, Shen; Lijie, Sun; Kaijian, Chen; Wei, Zhang; Xunchun, Wang

    2015-06-01

    Direct wafer bonding technology is able to integrate two smooth wafers and thus can be used in fabricating III–V multijunction solar cells with lattice mismatch. In order to monolithically interconnect between the GaInP/GaAs and InGaAsP/InGaAs subcells, the bonded GaAs/InP heterojunction must be a highly conductive ohmic junction or a tunnel junction. Three types of bonding interfaces were designed by tuning the conduction type and doping elements of GaAs and InP. The electrical properties of p-GaAs (Zn doped)/n-InP (Si doped), p-GaAs (C doped)/n-InP (Si doped) and n-GaAs (Si doped)/n-InP (Si doped) bonded heterojunctions were analyzed from the I–V characteristics. The wafer bonding process was investigated by improving the quality of the sample surface and optimizing the bonding parameters such as bonding temperature, bonding pressure, bonding time and so on. Finally, GaInP/GaAs/InGaAsP/InGaAs 4-junction solar cells have been prepared by a direct wafer bonding technique with the high efficiency of 34.14% at the AM0 condition (1 Sun). Project supported by the Shanghai Rising-Star Program (No. 14QB1402800).

  1. Geometric phases of water waves

    E-print Network

    Francesco Fedele

    2014-08-08

    Recently, Banner et al. (2014) highlighted a new fundamental property of open ocean wave groups, the so-called crest slowdown. For linear narrowband waves, this is related to the geometric and dynamical phase velocities $U_d$ and $U_g$ associated with the parallel transport through the principal fiber bundle of the wave motion with $\\mathit{U}(1)$ symmetry. The theoretical predictions are shown to be in fair agreement with ocean field observations, from which the average crest speed $c=U_d+U_g$ with $c/U_d\\approx0.8$ and $U_{g}/U_d\\approx-0.2$.

  2. Graphene with geometrically induced vorticity

    E-print Network

    Jiannis K. Pachos; Michael Stone; Kristan Temme

    2008-03-26

    At half filling, the electronic structure of graphene can be modelled by a pair of free two-dimensional Dirac fermions. We explicitly demonstrate that in the presence of a geometrically induced gauge field, an everywhere-real Kekule modulation of the hopping matrix elements can correspond to a non-real Higgs field with non-trivial vorticity. This provides a natural setting for fractionally charged vortices with localized zero modes. For fullerene-like molecules we employ the index theorem to demonstrate the existence of six low-lying states that do not depend strongly on the Kekule-induced mass gap.

  3. Geometric Buckling of Elliptical Cylinder

    SciTech Connect

    Murray, Raymond L. [North Carolina State University (United States)

    2005-07-15

    Research by Gast and Bournia on nuclear reactor cores in the form of elliptical cylinders is revisited. Derivations are presented, and data are extended in scope and accuracy. Findings on asymptotic series for constants needed in the evaluation of Mathieu functions are reported, along with accurate alternative techniques. Geometric bucklings are expressed in terms of circular cylinders with equivalent surface-to-volume ratios in a form that allows easy interpolation from tables. The estimation of extrapolation distances at boundaries of elliptical systems is addressed. Applications considered include a possible research reactor, the damage of fuel storage/shipping casks, and decommissioning of the damaged Windscale reactor.

  4. Geometric reasoning and spatial understanding

    SciTech Connect

    Binford, T.O.

    1982-01-01

    Progress has been made on extensions to ACRONYM which include: representation and reasoning with time, events, and sequences; collaboration with MIT to develop geometric learning: representation of function, and reasoning between structure and function. A new ribbon finder for ACRONYM is under construction. Work in figure/ground separation is underway as a basis for the ribbon finder. Preliminary results are shown in grouping operations to determine regularities in images. A stereo system has been completed which combines edge-based stereo matching with surface interpolation utilizing correspondence of gray levels. Design of a new stereo vision system is underway.

  5. Geometric analysis of wing sections

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    This paper describes a new geometric analysis procedure for wing sections. This procedure is based on the normal mode analysis for continuous functions. A set of special shape functions is introduced to represent the geometry of the wing section. The generators of the NACA 4-digit airfoils were included in this set of shape functions. It is found that the supercritical wing section, Korn airfoil, could be well represented by a set of ten shape functions. Preliminary results showed that the number of parameters to define a wing section could be greatly reduced to about ten. Hence, the present research clearly advances the airfoil design technology by reducing the number of design variables.

  6. Constrained ballistics and geometrical optics

    E-print Network

    Epstein, Marcelo

    2014-01-01

    The problem of constant-speed ballistics is studied under the umbrella of non-linear non-holonomic constrained systems. The Newtonian approach is shown to be equivalent to the use of Chetaev's rule to incorporate the constraint within the initially unconstrained formulation. Although the resulting equations are not, in principle, obtained from a variational statement, it is shown that the trajectories coincide with those of geometrical optics in a medium with a suitably chosen refractive index, as prescribed by Fermat's principle of least time. This fact gives rise to an intriguing mechano-optical analogy. The trajectories are further studied and discussed.

  7. Bond Illiquidity and Excess Volatility

    E-print Network

    Bao, Jack

    We find that the empirical volatilities of corporate bond and CDS returns are higher than implied by equity return volatilities and the Merton model. This excess volatility may arise because structural models inadequately ...

  8. Phase separation and glass transition point versus composition diagrams of binary mixtures with covalent bond between components

    Microsoft Academic Search

    Yu. D. Shibanov; Yu. K. Godovsky

    1985-01-01

    The geometric thermodynamics approach has been used for investigation of the possible glass transition point versus composition curves and their dependence on various parameters for both mixtures and systems with covalent bond between the components (block-, graftand star-polymers) in which phase separation is possible. Predicted relationships are compared with the experiment. Conditions have been determined under which glass transition hinders

  9. SPACE SHUTTLE EXTERNAL FUEL TANK DESIGN OPTIMIZATION

    Microsoft Academic Search

    Massimo Usan

    A design optimization study of the Space Shuttle External Fuel Tank (SSEFT) is performed using a model that, although simplified, captures some of the important aspects of the system's attributes and behavior. The goal of the optimization is to determine the values of the geometric characteristics of the system that maximize the ROI of the project and the payload that

  10. Differential Geometric Heuristics for Riemannian Optimal Mass Transportation

    E-print Network

    Delanoë, Philippe

    #µ = . Such a minimization problem is called a Monge's problem, after Gaspard Monge who was the first]. An essential tool for solving a Monge's problem is the notion of c-convexity. Dropping temporarily smoothness

  11. Geometric Programming optimization of deterministic inventory systems under multiple constraints 

    E-print Network

    Foster, Ralph Emerson

    1967-01-01

    & Scien loses Ahl! Glivers ty, n u in? the tcc&al c!uc for macro-economic analysis fo- a colnpany 0'- for thc'. national economy. !. 'Is 't" c. cs Ol tllC n ' !on' s occ an slhipp ing incustry inclicatc: Lilac the cost in it!Ill' anC! clallev Of' i...

  12. Application of generalized geometric programming to optimizing polynomials 

    E-print Network

    Gibson, Robert Engel

    1969-01-01

    g(X) = $ C g R i=1 j=1 may be computed using the equalities wl w2 g(x) =v(w) = ? ?? ?~ ~- H if there exists a unique set of w 's satisfying the conditions: (2-9) w. & 0 , i=1, 2, ~ ~ ~ , n, 1 (2. 10) n w i=1 and (2. 11) n a . wi = 0, j=1..., 2, ~ --, m. ij i If the rank r of the system matrix of (2. 10), (2. 11) is less than the rank of the augmented syst: em matrix, the system is inconsistent. In this case it may be conjectured that the minimum of g(x) is zero. If the solution to (2...

  13. Nonsmooth Coordination and Geometric Optimization via Distributed Dynamical Systems

    Microsoft Academic Search

    Jorge Cortes; Francesco Bullo

    2009-01-01

    Emerging applications for networked and cooperative robots motivate the study of motion coordination for groups of agents. For example, it is envisioned that groups of agents will perform a variety of useful tasks including surveillance, exploration, and environmental monitoring. This paper deals with basic interactions among mobile agents such as \\

  14. Geometric Facility Location Optimization Boaz Ben-Moshe

    E-print Network

    Ben-Moshe, Boaz

    -Gurion University Beer-Sheva 84105, Israel benmoshe@cs.bgu.ac.il April, 2005 #12;Acknowledgments First, I would like, and always fun. Eran Omri, Iris Ashkenzi, and Yuval Nir, who are the best company for doing real math while

  15. Geometric optimization methods for the analysis of gene expression data

    E-print Network

    Absil, Pierre-Antoine

    and Computer Science, University of Li`ege, Belgium. 2 Breast Cancer Functional Genomics Program, Cancer of data that unsupervised methods are required to reduce the dimension of the data set and to extract of the most popular algorithms to perform ICA. These algorithms are then applied on a microar- ray breast-cancer

  16. Optimal Biofilm Featues: metabolic and geometric response to multiple oxidants

    NASA Astrophysics Data System (ADS)

    Kempes, C.; Okegbe, C.; Mears-Clarke, Z.; Follows, M. J.; Dietrich, L.

    2014-12-01

    An important challenge in understanding complex microbial mat communities is determining how groups of a single species balance metabolic requirements with the dynamics of resource supply. We have investigated this problem in the context of redox resources within a single-species bacterial biofilm. We developed a mathematical model of oxidant availability and metabolic response within biofilm features and we show that observed biofilm geometries maximize cellular reproduction and growth efficiency. Our model accurately predicts the measured distribution of two types of electron acceptors: oxygen, which is available from the environment, and phenazines, redox-active small molecules produced by the bacterium. Because our model is based on resource dynamics, we are also able to predict observed shifts in feature geometry based on changes in the availability of redox resources such as variations in the external availability of oxygen or the removal of phenazines. This analysis suggests various avenues for understanding microstructure and the evolution of spatial metabolism in microbial mats.

  17. Parameterization and Geometric Optimization of Balloon Launched Sensorcraft for Atmospheric

    E-print Network

    Sóbester, András

    Atmospheric Science Through Robotic Aircraft SLS Selective Laser Sintering SLA Stereolithography FDM Fused images carry Windows 7 Phones and the Microsoft .NET Gadgeteer rapid electronic prototyping environment, process data onboard and use a wide variety of data transmission methods to relay the collected data

  18. Approximation schemes for NPhard geometric optimization problems: A survey

    E-print Network

    Arora, Sanjeev

    famous one is the traveling salesman problem (TSP): given n nodes in # 2 (more generally, in # d ), find in constant dimensions. (By ``constant dimensions'' we mean that we fix the dimension d and consider Steiner tree, the versions of TSP and Steiner tree respectively in which points lie in a metric space (i

  19. Optimal Range-Difference-Based Localization Considering Geometrical Constraints

    Microsoft Academic Search

    Adrian N. Bishop; Brian D. O. Anderson; Pubudu N. Pathirana

    2008-01-01

    This paper proposes a new type of algorithm aimed at finding the traditional maximum-likelihood (TML) estimate of the position of a target given time-difference-of-arrival (TDOA) information, contaminated by noise. The novelty lies in the fact that a performance index, akin to but not identical with that in maximum likelihood (ML), is a minimized subject to a number of constraints, which

  20. A Geometric Optimization Approach to Detecting and Intercepting Dynamic Targets

    E-print Network

    Ferrari, Silvia

    -pursuit problem considered in this paper is analogous to the Marco Polo game, in which the pursuer must capture is inspired by the game Marco Polo described in [13] and is motivated by many applications i

  1. Test Driving Three 1995 Genetic Algorithms: New Test Functions and Geometric Matching

    E-print Network

    Whitley, Darrell

    . 1 Introduction The use of genetic algorithms as optimization tools is now familiar to a broad rangeTest Driving Three 1995 Genetic Algorithms: New Test Functions and Geometric Matching D. Whitley, R, Colorado 80523 USA (303) 491­5373 whitley@cs.colostate.edu Abstract Genetic algorithms have attracted

  2. Mechanical Fault Patterns Identification and Grades Cognizance Based on Geometrical Learning

    Microsoft Academic Search

    Lijun Ding; Liang Hua; Hongwu Li

    2008-01-01

    This paper proposed a method of geometrical learning (GL) for identifying mechanical fault patterns and its grades. The method aimed at optimal covering for each class, and constructed some complicated geometry bodies (CGBs) to cover one class samples distributing in the feature space approximately. The rolling bearing was studied by GL-based method in this paper, firstly, energy spectrum was extracted

  3. Geometric Design Tools for Stiffness and Vibration Analysis of Robotic Mechanisms

    Microsoft Academic Search

    Jin Wook Kim; Frank C. Park; Munsang Kim

    2000-01-01

    We present a methodology for the first-order stiffness and vibration analysis of general robotic systems including parallel mechanisms, based on geometric methods for kinematics and elasticity analysis. We exploit the uniformity and structure typically extant in parallel mechanisms to develop an accurate and computationally tractable method of stiffness and vibration analysis that is amenable 60 design iterations and optimization. By

  4. The role of geometric constraints in amphiphilic self-assembly: A Brownian dynamics study

    E-print Network

    Bhattacharya, Aniket

    The role of geometric constraints in amphiphilic self-assembly: A Brownian dynamics study Geuorgui simulation method to investigate the effect of optimal head group area in amphiphilic self temperatures. Likewise, for a given concentration, amphiphiles with the larger effective head group exhibit

  5. Heuristic portfolio optimisation for a hedge fund strategy using the Geometric Nelder-Mead Algorithm

    Microsoft Academic Search

    Amadeo Alentorn; Alberto Moraglio; Colin Johnson

    2010-01-01

    This paper presents a framework for heuristic portfolio optimisation applied to a hedge fund investment strategy. The first contribution of the paper is to present a framework for implementing portfolio optimisation of a market neutral hedge fund strategy. The paper also illustrates the application of the recently developed Geometric Nelder-Mead Algorithm (GNMA) in solving this real world optimization problem, compared

  6. Geometric Nelder-Mead Algorithm on the Space of Genetic Programs

    E-print Network

    Yao, Xin

    Geometric Nelder-Mead Algorithm on the Space of Genetic Programs Alberto Moraglio School@{kdbio.inesc-id.pt,dei.uc.pt} ABSTRACT The Nelder-Mead Algorithm (NMA) is a close relative of Particle Swarm Optimization (PSO of genetic programs. The result is a Nelder-Mead Algorithm searching the space of genetic pro- grams

  7. Geometric nelder-mead algorithm on the space of genetic programs

    Microsoft Academic Search

    Alberto Moraglio; Sara Silva

    2011-01-01

    The Nelder-Mead Algorithm (NMA) is a close relative of Particle Swarm Optimization (PSO) and Differential Evolution (DE). In recent work, PSO, DE and NMA have been generalized using a formal geometric framework that treats solution representations in a uniform way. These formal algorithms can be used as templates to derive rigorously specific PSO, DE and NMA for both continuous and

  8. Computational Geometry Is the branch of computer science that studies algorithms for solving geometric

    E-print Network

    Dragan, Feodor F.

    . · optimal location of fire towers to view a region. · closest or most distant pair of points. · whether, · VLSI design · computer aided design · statistics · Deals with geometric objects such as points, line of lines. · finding vertices of a convex hull for points. · whether a line can be drawn separating two sets

  9. Tradeoff between delay and area in gate sizing using Geometric Programming

    Microsoft Academic Search

    Gracieli Posser; Guilherme Flach; Gustavo Wilke; Ricardo Reis

    2012-01-01

    A study about the tradeoff between delay and area (power) is presented in this work considering circuit gate sizing. We use a gate sizing tool based on Geometric Programming (GP), where delay is calculated by Elmore delay model. The optimization can be done targeting both delay and area (power) minimization. Tests were performed mapping ISCAS'85 benchmark circuits for 45nm technology.

  10. An expert system for optimal gear design

    SciTech Connect

    Lin, K.C.

    1988-01-01

    By properly developing the mathematical model, numerical optimization can be used to seek the best solution for a given set of geometric constraints. The process of determining the non-geometric design variables is automated by using symbolic computation. This gear-design system is built according to the AGMA standards and a survey of gear-design experts. The recommendations of gear designers and the information provided by AGMA standards are integrated into knowledge bases and data bases. By providing fast information retrieval and design guidelines, this expert system greatly streamlines the spur gear design process. The concept of separating the design space into geometric and non-geometric variables can also be applied to the design process for general mechanical elements. The expert-system techniques is used to simulate a human designer to optimize the process of determining non-geometric parameters, and the numerical optimization is used to identify for the best geometric solution. The combination of the expert-system technique with numerical optimization essentially eliminates the deficiencies of both methods and thus provides a better way of modeling the engineering design process.

  11. Geometric Routing in Wireless Sensor Networks

    Microsoft Academic Search

    Jie Gao

    \\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

  12. Geometrical and Graphical Solutions of Quadratic Equations.

    ERIC Educational Resources Information Center

    Hornsby, E. John, Jr.

    1990-01-01

    Presented are several geometrical and graphical methods of solving quadratic equations. Discussed are Greek origins, Carlyle's method, von Staudt's method, fixed graph methods and imaginary solutions. (CW)

  13. Thermodynamics of water structural reorganization due to geometric confinement

    NASA Astrophysics Data System (ADS)

    Stroberg, Wylie; Lichter, Seth

    2015-03-01

    Models of aqueous solvation have successfully quantified the behavior of water near convex bodies. However, many important processes occurring in aqueous solution involve interactions between solutes and surfaces with complicated non-convex geometries. Examples include the folding of proteins, hydrophobic association of solutes, ligand-receptor binding, and water confined within nanotubes and pores. For these geometries, models for solvation of convex bodies fail to account for the added interactions associated with structural confinement. Due to water's propensity to form networks of hydrogen bonds, small alterations to the confining geometry can induce large structural rearrangement within the water. We perform systematic Monte Carlo simulations of water confined to cylindrical cavities of varying aspect ratio to investigate how small geometric changes to the confining geometry may cause large changes to the structure and thermodynamic state of water. Using the Wang-Landau algorithm, we obtain free energies, enthalpies, entropies, and heat capacities across a broad range of temperatures, and show how these quantities are influenced by the structural rearrangement of water molecules due to geometric perturbations.

  14. Investigation of geometrical and scoring grid resolution for Monte Carlo dose calculations for IMRT

    NASA Astrophysics Data System (ADS)

    DeSmedt, B.; Vanderstraeten, B.; Reynaert, N.; DeNeve, W.; Thierens, H.

    2005-09-01

    Monte Carlo based treatment planning of two different patient groups treated with step-and-shoot IMRT (head-and-neck and lung treatments) with different CT resolutions and scoring methods is performed to determine the effect of geometrical and scoring voxel sizes on DVHs and calculation times. Dose scoring is performed in two different ways: directly into geometrical voxels (or in a number of grouped geometrical voxels) or into scoring voxels defined by a separate scoring grid superimposed on the geometrical grid. For the head-and-neck cancer patients, more than 2% difference is noted in the right optical nerve when using voxel dimensions of 4 × 4 × 4 mm3 compared to the reference calculation with 1 × 1 × 2 mm3 voxel dimensions. For the lung cancer patients, 2% difference is noted in the spinal cord when using voxel dimensions of 4 × 4 × 10 mm3 compared to the 1 × 1 × 5 mm3 calculation. An independent scoring grid introduces several advantages. In cases where a relatively high geometrical resolution is required and where the scoring resolution is less important, the number of scoring voxels can be limited while maintaining a high geometrical resolution. This can be achieved either by grouping several geometrical voxels together into scoring voxels or by superimposing a separate scoring grid of spherical voxels with a user-defined radius on the geometrical grid. For the studied lung cancer cases, both methods produce accurate results and introduce a speed increase by a factor of 10-36. In cases where a low geometrical resolution is allowed, but where a high scoring resolution is required, superimposing a separate scoring grid on the geometrical grid allows a reduction in geometrical voxels while maintaining a high scoring resolution. For the studied head-and-neck cancer cases, calculations performed with a geometrical resolution of 2 × 2 × 2 mm3 and a separate scoring grid containing spherical scoring voxels with a radius of 2 mm produce accurate results and introduce a speed increase by a factor of 13. The scoring grid provides an additional degree of freedom for limiting calculation time and memory requirements by selecting optimized scoring and geometrical voxel dimensions in an independent way.

  15. Enzymatic reduction of disulfide bonds in lysosomes: Characterization of a Gamma-interferon-inducible lysosomal thiol reductase (GILT)

    Microsoft Academic Search

    Balasubramanian Arunachalam; Uyen T. Phan; Hans J. Geuze; Peter Cresswell

    2000-01-01

    Proteins internalized into the endocytic pathway are usually degraded. Efficient proteolysis requires denaturation, induced by acidic conditions within lysosomes, and reduction of inter- and intrachain disulfide bonds. Cytosolic reduction is mediated enzymatically by thioredoxin, but the mechanism of lysosomal reduction is unknown. We describe here a lysosomal thiol reductase optimally active at low pH and capable of catalyzing disulfide bond

  16. Nickel-Catalyzed C?O/C?H Cross-Coupling Reactions for C?C Bond Formation.

    PubMed

    Chen, Tieqiao; Han, Li-Biao

    2015-07-20

    Halides not required: Nickel-catalyzed C?O/C?H cross-couplings for the construction of C?C bonds have recently been disclosed. By carefully optimizing the nickel catalyst, new C?C bond-forming reactions were developed, and even quaternary stereogenic centers are now accessible in high yields from readily available phenoxide derivatives and hydrocarbons. PMID:26073575

  17. Effect of P lasma Treatment of Au\\/Ni\\/Cu b ond pads on Process Windows of Au Wire Bonding

    Microsoft Academic Search

    Yu Hin Chan; Deming Liu; Kee Liu; Yiu Ming Cheung; Ming Wai Ng

    The wire bondability of Au\\/Ni\\/Cu bond pads with different Au plating schemes, including electrolytic and immersion plates, are evaluated after plasma treatment. The plasma cleaning conditions, such as cleaning power and time, are optimized bas ed on the process window and wire pull strength measurements for different bond pad temperatures. Difference in the efficiency of plasma treatment in improving the

  18. The challenges of copper wire bonding

    Microsoft Academic Search

    C. T.-h. Lu

    2010-01-01

    Advantages of Cu wire bonding, such as less wire sweep, better performance for analog devices, are interpreted by its material properties. Alternative aspect from material properties on Cu wire bonding parameters is proposed to reflect the fact that Cu wire bonding may not necessarily damage the existing under-pad structure of integrated circuit designed for Au wire bonding. The challenge of

  19. School Bond Success: An Exploratory Case Study

    ERIC Educational Resources Information Center

    Holt, Carleton R.; Wendt, Matthew A,; Smith, Roland M.

    2006-01-01

    Following two-failed school bond issues in 1995 and 1998, one mid-sized rural school district organized an effort that led to two successful school bond elections in 2001 and 2003. The school district's strategic plan mirrored many of the recommendations for successful bond referendums published in School Bond Success: A Strategy for Building…

  20. Fine pitch copper wire bonding — Why now?

    Microsoft Academic Search

    Bernd K. Appelt; Andy Tseng; Yi-Shao Lai

    2009-01-01

    Fine pitch Cu wire bonding is at the cusp of becoming main stream. Many challenges had to be overcome when making the transition from fine pitch Au wire bonding to fine pitch Cu wire bonding in a high volume manufacturing environment. The challenges for Cu wire bonding arise from the inherent properties of Cu: propensity to oxidize, increased hardness, slow

  1. 43 CFR 3474.1 - Bonding requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Bonding requirements. 3474.1 Section 3474...AND LIMITATIONS Bonds § 3474.1 Bonding requirements. (a) Before a lease...approved by the Director. (c) The bonding obligation for a new lease may be...

  2. 43 CFR 3474.1 - Bonding requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Bonding requirements. 3474.1 Section 3474...AND LIMITATIONS Bonds § 3474.1 Bonding requirements. (a) Before a lease...approved by the Director. (c) The bonding obligation for a new lease may be...

  3. 43 CFR 3474.1 - Bonding requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Bonding requirements. 3474.1 Section 3474...AND LIMITATIONS Bonds § 3474.1 Bonding requirements. (a) Before a lease...approved by the Director. (c) The bonding obligation for a new lease may be...

  4. 36 CFR 228.51 - Bonding.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Bonding. 228.51 Section 228.51 Parks...Materials General Provisions § 228.51 Bonding. (a) Bond requirements...where the authorized officer may waive such bonding. If an extension of time is...

  5. 36 CFR 228.51 - Bonding.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Bonding. 228.51 Section 228.51 Parks...Materials General Provisions § 228.51 Bonding. (a) Bond requirements...where the authorized officer may waive such bonding. If an extension of time is...

  6. 36 CFR 228.51 - Bonding.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Bonding. 228.51 Section 228.51 Parks...Materials General Provisions § 228.51 Bonding. (a) Bond requirements...where the authorized officer may waive such bonding. If an extension of time is...

  7. 36 CFR 228.51 - Bonding.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Bonding. 228.51 Section 228.51 Parks...Materials General Provisions § 228.51 Bonding. (a) Bond requirements...where the authorized officer may waive such bonding. If an extension of time is...

  8. 36 CFR 228.51 - Bonding.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Bonding. 228.51 Section 228.51 Parks...Materials General Provisions § 228.51 Bonding. (a) Bond requirements...where the authorized officer may waive such bonding. If an extension of time is...

  9. 43 CFR 3474.1 - Bonding requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Bonding requirements. 3474.1 Section 3474...AND LIMITATIONS Bonds § 3474.1 Bonding requirements. (a) Before a lease...approved by the Director. (c) The bonding obligation for a new lease may be...

  10. Natural bond orbital analysis, electronic structure and vibrational spectral analysis of N-(4-hydroxyl phenyl) acetamide: a density functional theory.

    PubMed

    Govindasamy, P; Gunasekaran, S; Ramkumaar, G R

    2014-09-15

    The Fourier transform infrared (FT-IR) and FT-Raman spectra of N-(4-hydroxy phenyl) acetamide (N4HPA) of painkiller agent were recorded in the region 4000-450 cm(-1) and 4000-50 cm(-1) respectively. Density functional theory (DFT) has been used to calculate the optimized geometrical parameter, atomic charges, and vibrational wavenumbers and intensity of the vibrational bands. The computed vibrational wave numbers were compared with the FT-IR and FT-Raman experimental data. The computational calculations at DFT/B3LYP level with 6-31G(d,p), 6-31++G(d,p), 6-311G(d,p) and 6-311++G(d,p) basis sets. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using Vibrational energy distribution analysis (VEDA 4) program. The oscillator's strength calculated by TD-DFT and N4HPA is approach complement with the experimental findings. The NMR chemical shifts 13C and 1H were recorded and calculated using the gauge independent atomic orbital (GIAO) method. The molecular electrostatic potential (MESP) and electron density surfaces of the molecule were constructed. The Natural charges and intermolecular contacts have been interpreted using Natural Bond orbital (NBO) analysis the HOMO-LUMO energy gap has been calculated. The thermodynamic properties like entropy, heat capacity and zero vibrational energy have been calculated. PMID:24813292

  11. Evolutionary optimization of a Genetically Refined Truss

    NASA Technical Reports Server (NTRS)

    Hull, Patrick V.; Tinker, Michael L.; Dozier, Gerry

    2005-01-01

    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 paper will present 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. An non-traditional solution to the benchmark problem is presented in this paper, 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.

  12. SiO and GeO bonded interactions as inferred from the bond critical point properties of electron density distributions

    NASA Astrophysics Data System (ADS)

    Gibbs, G. V.; Boisen, M. B.; Hill, F. C.; Tamada, O.; Downs, R. T.

    The topological properties of the electron density distributions for more than 20 hydroxyacid, geometry optimized molecules with SiO and GeO bonds with 3-, 4-, 6- and 8-coordinate Si and Ge cations were calculated. Electronegativities calculated with the bond critical point (bcp) properties of the distributions indicate, for a given coordination number, that the electronegativity of Ge ( 1.85) is slightly larger than that of Si ( 1.80) with the electronegativities of both atoms increasing with decreasing bond length. With an increase in the electron density, the curvatures and the Laplacian of the electron density at the critical point of each bond increase with decreasing bond length. The covalent character of the bonds are assessed, using bond critical point properties and electronegativity values calculated from the electron density distributions. A mapping of the (3, -3) critical points of the valence shell concentrations of the oxide anions for bridging SiOSi and GeOGe dimers reveals a location and disposition of localized nonbonding electron pairs that is consistent with the bridging angles observed for silicates and germanates. The bcp properties of electron density distributions of the SiO bonds calculated for representative molecular models of the coesite structure agree with average values obtained in X-ray diffraction studies of coesite and danburite to within 5%.

  13. "Vibrational bonding": a new type of chemical bond is discovered.

    PubMed

    Rhodes, Christopher J; Macrae, Roderick M

    2015-01-01

    A long-sought but elusive new type of chemical bond, occurring on a minimum-free, purely repulsive potential energy surface, has recently been convincingly shown to be possible on the basis of high-level quantum-chemical calculations. This type of bond, termed a vibrational bond, forms because the total energy, including the dynamical energy of the nuclei, is lower than the total energy of the dissociated products, including their vibrational zero-point energy. For this to be the case, the ZPE of the product molecule must be very high, which is ensured by replacing a conventional hydrogen atom with its light isotope muonium (Mu, mass = 1/9 u) in the system Br-H-Br, a natural transition state in the reaction between Br and HBr. A paramagnetic species observed in the reaction Mu +Br2 has been proposed as a first experimental sighting of this species, but definitive identification remains challenging. PMID:25942773

  14. Three methods to measure RH bond energies

    SciTech Connect

    Berkowitz, J. [Argonne National Lab., IL (United States); Ellison, G.B. [Univ. of Colorado, Boulder, CO (United States). Dept. of Chemistry and Biochemistry; Gutman, D. [Catholic Univ. of America, Washington, DC (United States). Dept. of Chemistry

    1993-03-21

    In this paper the authors compare and contrast three powerful methods for experimentally measuring bond energies in polyatomic molecules. The methods are: radical kinetics; gas phase acidity cycles; and photoionization mass spectroscopy. The knowledge of the values of bond energies are a basic piece of information to a chemist. Chemical reactions involve the making and breaking of chemical bonds. It has been shown that comparable bonds in polyatomic molecules, compared to the same bonds in radicals, can be significantly different. These bond energies can be measured in terms of bond dissociation energies.

  15. Methodology and method and appartus for signaling with capacity optimized constellations

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    Communication systems are described that use geometrically shaped constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. In several embodiments, the geometrically shaped is optimized based upon a capacity measure such as parallel decoding capacity or joint capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel.

  16. Influence of hydrogen bonding on the geometry of the adenine fragment

    Microsoft Academic Search

    Joanna Maria Slowikowska; Krzysztof Wo?niak

    1996-01-01

    The crystal structures of two adenine derivatives, N(6),9-dimethyl-8-butyladenine (I) and its hydrate (1:1) (II), have been determined by single-crystal X-ray diffraction. The geometrical features of both structures are discussed. The influence of protonation, substitution and hydrogen bond formation on the geometry of the adenine fragment was studied, based on data retrieved from the Cambridge Structural Database. Total correlation analysis showed

  17. Influence of hydrogen bonding on the geometry of the adenine fragment

    Microsoft Academic Search

    Joanna Maria S?owikowska; Krzysztof Wo?niak

    1996-01-01

    The crystal structures of two adenine derivatives, N(6),9-dimethyl-8-butyladenine (I) and its hydrate (1 : 1) (II), have been determined by single-crystal X-ray diffraction. The geometrical features of both structures are discussed. The influence of protonation, substitution and hydrogen bond formation on the geometry of the adenine fragment was studied, based on data retrieved from the Cambridge Structural Database. Total correlation

  18. The structure of betaxolol from single crystal X-ray diffraction and natural bond orbital analysis

    Microsoft Academic Search

    João Canotilho; Ricardo A. E. Castro; Mário T. S. Rosado; M. Ramos Silva; A. Matos Beja; J. A. Paixão; J. Simões Redinha

    2008-01-01

    The structure of betaxolol obtained from ethanol:water solution was studied by X-ray diffraction. The geometrical parameters needed to define the structure are tabulated. The X-ray data show the existence of two conformers in the unit cell differing only in the conformation of the cyclopropylmethoxy fragment. Differences in the bond lengths angles and dihedral between both conformations are observed. The cyclopropyl

  19. Autophoretic locomotion from geometric asymmetry

    E-print Network

    Sebastien Michelin; Eric Lauga

    2015-01-16

    Among the few methods which have been proposed to create small-scale swimmers, those relying on self-phoretic mechanisms present an interesting design challenge in that chemical gradients are required to generate net propulsion. Building on recent work, we propose that asymmetries in geometry are sufficient to induce chemical gradients and swimming. We illustrate this idea using two different calculations. We first calculate exactly the self-propulsion speed of a system composed of two spheres of unequal sizes but identically chemically homogeneous. We then consider arbitrary, small-amplitude, shape deformations of a chemically-homogeneous sphere, and calculate asymptotically the self-propulsion velocity induced by the shape asymmetries. Our results demonstrate how geometric asymmetries can be tuned to induce large locomotion speeds without the need of chemical patterning.

  20. Autophoretic locomotion from geometric asymmetry

    E-print Network

    Michelin, Sebastien

    2015-01-01

    Among the few methods which have been proposed to create small-scale swimmers, those relying on self-phoretic mechanisms present an interesting design challenge in that chemical gradients are required to generate net propulsion. Building on recent work, we propose that asymmetries in geometry are sufficient to induce chemical gradients and swimming. We illustrate this idea using two different calculations. We first calculate exactly the self-propulsion speed of a system composed of two spheres of unequal sizes but identically chemically homogeneous. We then consider arbitrary, small-amplitude, shape deformations of a chemically-homogeneous sphere, and calculate asymptotically the self-propulsion velocity induced by the shape asymmetries. Our results demonstrate how geometric asymmetries can be tuned to induce large locomotion speeds without the need of chemical patterning.