WorldWideScience

Sample records for nonlinear material behavior

  1. Nonlinear constitutive behavior of ferroelectric materials

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The ferroelectric specimen is considered as an aggregation of many randomly oriented domains. According to this mechanism,a multi-domain mechanical model is developed in this paper. Each domain is represented by one element. The applied stress and electric field are taken to be the stress and electric field in the formula of the driving force of domain switching for each element in the specimen. It means that the macroscopic switching criterion is used for calculating the volume fraction of domain switching for each element. By using the hardening relation between the driving force of domain switching and the volume fraction of domain switching calibrated,the volume fraction of domain switching for each element is calculated. Substituting the stress and electric field and the volume fraction of domain switching into the constitutive equation of ferroelectric material,one can easily get the strain and electric displacement for each element. The macroscopic behavior of the ferroelectric specimen is then directly calculated by volume averaging. Mean-while,the nonlinear finite element analysis for the ferroelectric specimen is carried out. In the finite element simulation,the volume fraction of domain switching for each element is calculated by using the same method mentioned above. The in-teraction between different elements is taken into account in the finite element simulation and the local stress and electric field for each element is obtained. The macroscopic behavior of the specimen is then calculated by volume averaging. The computation results involve the electric butterfly shaped curves of axial strain versus the axial electric field and the hysteresis loops of electric displacement versus the electric field for ferroelectric specimens under the uniaxial coupled stress and electric field loading. The present theoretical prediction agrees reasonably with the experimental results.

  2. Nonlinear elastic behavior of phantom materials for elastography

    Energy Technology Data Exchange (ETDEWEB)

    Pavan, Theo Z; Madsen, Ernest L; Frank, Gary R; Hall, Timothy J [Medical Physics Department, University of Wisconsin, Room 1005, Wisconsin Institutes for Medical Research, 1111 Highland Avenue, Madison, WI 53705 (United States); Adilton O Carneiro, Antonio, E-mail: tjhall@wisc.ed [Departamento de Fisica e Matematica, FFCLRP, Universidade de Sao Paulo, Av. Bandeirantes, 3900, Monte Alegre, Ribeirao Preto, Sao Paulo (Brazil)

    2010-05-07

    The development of phantom materials for elasticity imaging is reported in this paper. These materials were specifically designed to provide nonlinear stress/strain relationship that can be controlled independently of the small strain shear modulus of the material. The materials are mixtures of agar and gelatin gels. Oil droplet dispersions in these materials provide further control of the small strain shear modulus and the nonlinear parameter of the material. Since these materials are mostly water, they are assumed to be incompressible under typical experimental conditions in elasticity imaging. The Veronda-Westman model for strain energy density provided a good fit to all materials used in this study. Materials with a constant gelatin concentration (3.0% dry weight) but varying agar concentration (0.6-2.8% dry weight) demonstrated the same power law relationship between elastic modulus and agar concentration found for pure agar (1.89 {+-} 0.02), consistent with percolation theory, and provided a consistent nonlinearity parameter of 4.5 {+-} 0.3. The insights provided by this study will form the basis for stable elastography phantoms with stiffness and nonlinear stress/strain relationships in the background that differ from those in the target.

  3. Nonlinear Materials Characterization Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Nonlinear Materials Characterization Facility conducts photophysical research and development of nonlinear materials operating in the visible spectrum to protect...

  4. Nonlinear optical materials.

    Science.gov (United States)

    Eaton, D F

    1991-07-19

    The current state of materials development in nonlinear optics is summarized, and the promise of these materials is critically evaluated. Properties and important materials constants of current commercial materials and of new, promising, inorganic and organic molecular and polymeric materials with potential in second- and third-order nonlinear optical applications are presented.

  5. Organic nonlinear optical materials

    Science.gov (United States)

    Umegaki, S.

    1987-01-01

    Recently, it became clear that organic compounds with delocalized pi electrons show a great nonlinear optical response. Especially, secondary nonlinear optical constants of more than 2 digits were often seen in the molecular level compared to the existing inorganic crystals such as LiNbO3. The crystallization was continuously tried. Organic nonlinear optical crystals have a new future as materials for use in the applied physics such as photomodulation, optical frequency transformation, opto-bistabilization, and phase conjugation optics. Organic nonlinear optical materials, e.g., urea, O2NC6H4NH2, I, II, are reviewed with 50 references.

  6. Variational principles for nonlinear piezoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Ramos, R.; Guinovart-Diaz, R. [Universidad de la Habana, Facultad de Matematica y Computacion, Vedado, Habana (Cuba); Pobedria, B.E. [Moscow State University M. V. Lomonosov, Composites Department, Moscow (Russian Federation); Padilla, P. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Matematicas Aplicadas y en Sistemas (IIMAS), Cd. Universitaria, Mexico D.F. (Mexico); Bravo-Castillero, J. [Universidad de la Habana, Facultad de Matematica y Computacion, Vedado, Habana (Cuba); Campus Estado de Mexico. Division de Arquitectura e Ingenieria, Instituto Tecnologico de Estudios Superiores de Monterrey, Atizapan de Zaragoza, Estado de Mexico (Mexico); Maugin, G.A. [Universite Pierre et Marie Curie. Case 162, UMR 7607 CNRS, Laboratoire de Modelisation en Mecanique, Paris Cedex 05 (France)

    2004-12-01

    In the present paper, we consider the behavior of nonlinear piezoelectric materials by generalization for this case of the Hashin-Shtrikman variational principles. The new general formulation used here differs from others, because, it gives the possibility to evaluate the upper and lower Hashin-Shtrikman bounds for specific physical nonlinearities of piezoelectric materials. Geometrical nonlinearities are not considered. (orig.)

  7. Nonlinearities in Behavioral Macroeconomics.

    Science.gov (United States)

    Gomes, Orlando

    2017-07-01

    This article undertakes a journey across the literature on behavioral macroeconomics, with attention concentrated on the nonlinearities that the behavioral approach typically suggests or implies. The emphasis is placed on thinking the macro economy as a living organism, composed of many interacting parts, each one having a will of its own, which is in sharp contrast with the mechanism of the orthodox view (well represented by the neoclassical or new Keynesian dynamic stochastic general equilibrium - DSGE - model). The paper advocates that a thorough understanding of individual behavior in collective contexts is the only possible avenue to further explore macroeconomic phenomena and the often observed 'anomalies' that the benchmark DSGE macro framework is unable to explain or justify. After a reflection on the role of behavioral traits as a fundamental component of a new way of thinking the economy, the article proceeds with a debate on some of the most relevant frameworks in the literature that somehow link macro behavior and nonlinearities; covered subjects include macro models with disequilibrium rules, agent-based models that highlight interaction and complexity, evolutionary switching frameworks, and inattention based decision problems. These subjects have, as a fundamental point in common, the use of behavioral elements to transform existing interpretations of the economic reality, making it more evident how irregular fluctuations emerge and unfold on the aggregate.

  8. Variational principles for linear and nonlinear mixtures: New derivations and application to bilinear materials and yield behavior

    Science.gov (United States)

    Alqaraleh, Sahar Mubarak

    2006-04-01

    We study in this paper the effective energy potential of nonlinear composites in terms of the corresponding energy potential for linear material. We study this for power law material using Suquet's variational principle, for bilinear material using Ponte Castaneda variational principle, and we studied the yield behavior as limiting cases of both. We show that three established variational principles can be derived from the Cauchy-Buniakowski-Schwartz inequality; these variational principles (bounds) are: (a) bounds on yield behavior of mixtures, (b) The Hashin-Shtrikman variational principle for linear materials, (c) The Debotton and Ponte Castaneda bound for power-law polycrystals. We also compute the actual stress and strain fields for laminate material for two choices of the average strain, and compute a bound on the effective potential for spherical inclusions using Hashin's linear bound, as well as for spheroidal inclusions using Willis's linear bound. We obtained bounds sharper than the established bounds for both laminate and aligned ellipsoids geometry, and we investigate also how the bound depends on the specified geometry and on specific parameters of the problem.

  9. Nonlinear elastic waves in materials

    CERN Document Server

    Rushchitsky, Jeremiah J

    2014-01-01

    The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...

  10. Nonlinear optics and organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Y.R.

    1994-07-01

    We shall consider an interesting topic relating nonlinear optics and organic materials: how nonlinear optics can be used to study organic materials. One of the main differences between linear and nonlinear responses of a medium to incoming radiation is in their symmetries. It leads to the possibility that some properties of the medium could be more sensitively probed by nonlinear, rather than linear, optical means, or vise versa. A well-known example is that some vibrational modes of a medium could be Raman-active but infrared-inactive, and would be more readily observed by Raman scattering, which is a two-photon transition process. In this paper, we shall discuss, with the help of three examples, how we can use second harmonic generation (SHG) and sum frequency generation (SFG) to obtain unique information about a material. We shall focus on thin films, surfaces, and interfaces.

  11. Effects of nonlinearity in the materials used for the semi-rigid pedicle screw systems on biomechanical behaviors of the lumbar spine after surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun; Lee, Sung-Jae [Department of Biomedical Engineering, Inje University, Gimhae 621749 (Korea, Republic of); Lim, Do-Hyung [Korea Institute of Industrial Technology, Cheonan 331825 (Korea, Republic of); Oh, Hyun-Ju [Korea Food and Drug Administration, Seoul 363951 (Korea, Republic of); Lee, Kwon-Yong, E-mail: sjl@bme.inje.ac.kr [Department of Mechanical Engineering, Sejong University, Seoul 143747 (Korea, Republic of)

    2011-10-15

    Recently, various types of semi-rigid pedicle screw fixation systems have been developed for the surgical treatment of the lumbar spine. They were introduced to address the adverse issues commonly found in traditional rigid spinal fusion--abnormally large motion at the adjacent level and subsequent degeneration. The semi-rigid system uses more compliant materials (nitinol or polymers) and/or changes in rod design (coiled or twisted rods) as compared to the conventional rigid straight rods made of Ti alloys (E = 114 GPa, {upsilon} = 0.32). However, biomechanical studies on the semi-rigid pedicle screw systems were usually limited to linear modeling of the implant and anatomic elements, which may not be capable of reflecting realistic post-operative motions of the spine. In this study, we evaluated the effects of nonlinearity in materials used for semi-rigid pedicle screw fixation systems to evaluate the changes in biomechanical behaviors using finite element analysis. Changes in range of motion (ROM) and center of rotation (COR) were assessed at the operated and adjacent levels. Actual load-displacement results of the semi-rigid rod from mechanical test were carried out to reflect the nonlinearity of the implant. In addition, nonlinear material properties of various spinal ligaments studies were used for the finite element modeling. The post-operative models were constructed by modifying the previously validated intact model of the L1-S1 spine. Eight different post-operative models were made to address the effects of nonlinearity-with a traditional stiffness modulus rod (with linear ligaments, case 1; with nonlinear ligaments, case 5), with a rigid rod (with linear ligaments, case 2; with nonlinear ligaments, case 6), with a soft rod (with linear ligaments, case 3; with nonlinear ligaments, case 7), and with a nonlinear rod (with linear ligaments, case 4; with nonlinear ligaments, case 8). To simulate the load on the lumbar spine in a neutral posture, follower load

  12. Design of materials with prescribed nonlinear properties

    DEFF Research Database (Denmark)

    Wang, Fengwen; Sigmund, Ole; Jensen, Jakob Søndergaard

    2014-01-01

    We systematically design materials using topology optimization to achieve prescribed nonlinear properties under finite deformation. Instead of a formal homogenization procedure, a numerical experiment is proposed to evaluate the material performance in longitudinal and transverse tensile tests un....... The numerical examples illustrate optimized materials with rubber-like behavior and also optimized materials with extreme strain-independent Poisson's ratio for axial strain intervals of εi ∈ [0.00,0.30]. © 2014 Elsevier Ltd. All rights reserved....... under finite deformation, i.e. stress-strain relations and Poisson's ratio. By minimizing errors between actual and prescribed properties, materials are tailored to achieve the target. Both two dimensional (2D) truss-based and continuum materials are designed with various prescribed nonlinear properties...

  13. Optically nonlinear materials

    CERN Document Server

    Whittam, A J

    2001-01-01

    susceptibility from 26 pm/V (same film without octadecanoic acid) to 40 pm/V. This increase in the second-order susceptibility occurred even though the amount of NLO-active dye was effectively diluted by the addition of the inactive octadecanoic acid. The wavelength of the absorption maximum ranged from 346-440 nm and there was direct correlation between the susceptibilities and the transparency of the films at the harmonic wavelength. Hemicyanine dyes were synthesised, with the general formulae: - (a) C sub 1 sub 8 H sub 3 sub 7 -A sup + -[CH=CH-C sub 6 H sub 4] sub x -N(CH sub 3) sub 2 I (b) C sub 1 sub 8 H sub 3 sub 7 -A sup + -[CH=CH] sub y -C sub 6 H sub 4 -N(CH sub 3) sub 2 I where A sup + is a pyridinium or isoquinolinium acceptor, and x = 1 or 2, and y = 1 or 2. The optically nonlinear dyes were investigated via the Langmuir-Blodgett (LB) technique. The dyes all produced isotherm data, with molecular areas of 22-60 A sup 2 per molecule, which are consistent with the cross-sectional areas of the chromo...

  14. New nonlinear optical materials based on ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J P [Department of Physics, Fudan University, Shanghai 200433 (China); Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Institute of Theoretical Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China); Yu, K W [Department of Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China); Institute of Theoretical Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China)

    2006-01-01

    We exploit theoretically a new class of magneto-controlled nonlinear optical material based on ferrofluids in which ferromagnetic nanoparticles are coated with a nonmagnetic metallic nonlinear shell. Such an optical material can have anisotropic nonlinear optical properties and a giant enhancement of nonlinearity, as well as an attractive figure of merit.

  15. Graphene - a rather ordinary nonlinear optical material

    CERN Document Server

    khurgin, Jacob B

    2014-01-01

    An analytical expression for the nonlinear refractive index of graphene has been derived and used to obtain the performance metrics of third order nonlinear devices using graphene as a nonlinear medium. None of the metrics is found to be superior to the existing nonlinear optical materials.

  16. Modeling of unusual nonlinear behaviors in superconducting microstrip transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Javadzadeh, S. Mohammad Hassan, E-mail: smh_javadzadeh@ee.sharif.edu [School of Electrical Engineering, Sharif University of Technology, P.O. Box 11365-9363, Tehran (Iran, Islamic Republic of); Farzaneh, Forouhar; Fardmanesh, Mehdi [School of Electrical Engineering, Sharif University of Technology, P.O. Box 11365-9363, Tehran (Iran, Islamic Republic of)

    2013-03-15

    Highlights: ► Avoiding of considering just quadratic or modulus nonlinearity. ► Proposing a nonlinear model to predict unusual nonlinear behaviors at low temperatures. ► Description of temperature dependency of nonlinear behaviors in superconducting lines. ► Analytical formulation for each parameter in our proposed model. ► Obtaining very good results which shows this model can predict unusual nonlinear behavior. -- Abstract: There are unusual nonlinear behaviors in superconducting materials, especially at low temperatures. This paper describes the procedure to reliably predict this nonlinearity in superconducting microstrip transmission lines (SMTLs). An accurate nonlinear distributed circuit model, based on simultaneously considering of both quadratic and modulus nonlinearity dependences, is proposed. All parameters of the equivalent circuit can be calculated analytically using proposed closed-form expressions. A numerical method based on Harmonic Balance approach is used to predict nonlinear phenomena like intermodulation distortions and third harmonic generations. Nonlinear analyses of the SMTLs at the different temperatures and the input powers have been presented. This proposed model can describe the unusual behaviors of the nonlinearity at low temperatures, which are frequently observed in the SMTLs.

  17. A nonlinear Hermitian transfinite element method for transient behavior analysis of hollow functionally graded cylinders with temperature-dependent materials under thermo-mechanical loads

    Energy Technology Data Exchange (ETDEWEB)

    Shariyat, M. [Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: m_shariyat@yahoo.com

    2009-04-15

    In the present paper, an algorithm for nonlinear transient behavior analysis of thick functionally graded cylindrical vessels or pipes with temperature-dependent material properties under thermo-mechanical loads is presented. In contrast to researches presented so far, a Hermitian transfinite element method is proposed to improve the accuracy and to prevent artificial interference or cohesion formation at the mutual boundaries of the elements. Time variations of the temperatures, displacements, and stresses are obtained through a numerical Laplace inversion. Another novelty of the present research is using the transfinite element method to solve nonlinear problems. A sensitivity analysis includes investigating effects of the volume fraction index, dimensions, and temperature-dependency of the material properties is performed. Results confirm the efficiency of the present algorithm and reveal the significant effects of the temperature-dependency of the material properties and the elastic wave reflections and interferences on the responses. In comparison to other techniques, the present technique may be used to obtain relatively accurate and stable results in a less computational time.

  18. Nonlinear behavior of Helmholtz resonators

    Science.gov (United States)

    Hersh, A. S.

    1990-10-01

    A semi-empirical fluid mechanical model has been derived to predict the nonlinear acoustic behavior of thin-walled, single-orifice Helmholtz resonators. The model assumed that the sound particle velocity field approaches the resonator in a spherically symmetric manner. The incident and cavity sound pressure fields are connected in terms of an orifice discharge coefficient and an end correction parameter whose values are determined empirically. The accuracy of the model was verified by comparing predicted with measured impedance over a wide range of sound amplitudes and frequencies for two different resonator geometries and with measurements conducted by Ingard and Ising.

  19. Advances in nonlinear optical materials and devices

    Science.gov (United States)

    Byer, Robert L.

    1991-01-01

    The recent progress in the application of nonlinear techniques to extend the frequency of laser sources has come from the joint progress in laser sources and in nonlinear materials. A brief summary of the progress in diode pumped solid state lasers is followed by an overview of progress in nonlinear frequency extension by harmonic generation and parametric processes. Improved nonlinear materials including bulk crystals, quasiphasematched interactions, guided wave devices, and quantum well intersubband studies are discussed with the idea of identifying areas of future progress in nonlinear materials and devices.

  20. Nonlinear dynamics in human behavior

    Energy Technology Data Exchange (ETDEWEB)

    Huys, Raoul [Centre National de la Recherche Scientifique (CNRS), 13 - Marseille (France); Marseille Univ. (France). Movement Science Inst.; Jirsa, Viktor K. (eds.) [Centre National de la Recherche Scientifique (CNRS), 13 - Marseille (France); Marseille Univ. (France). Movement Science Inst.; Florida Atlantic Univ., Boca Raton, FL (United States). Center for Complex Systems and Brain Sciences

    2010-07-01

    Humans engage in a seemingly endless variety of different behaviors, of which some are found across species, while others are conceived of as typically human. Most generally, behavior comes about through the interplay of various constraints - informational, mechanical, neural, metabolic, and so on - operating at multiple scales in space and time. Over the years, consensus has grown in the research community that, rather than investigating behavior only from bottom up, it may be also well understood in terms of concepts and laws on the phenomenological level. Such top down approach is rooted in theories of synergetics and self-organization using tools from nonlinear dynamics. The present compendium brings together scientists from all over the world that have contributed to the development of their respective fields departing from this background. It provides an introduction to deterministic as well as stochastic dynamical systems and contains applications to motor control and coordination, visual perception and illusion, as well as auditory perception in the context of speech and music. (orig.)

  1. Design of Organic Nonlinear Optical Materials

    Science.gov (United States)

    1990-06-01

    This project deals with a new approach to designing organic nonlinear optical materials for second harmonic generation based on the use of hydrogen...patterns for even simple organic molecules. For organic nonlinear optical materials this dilemma means that even the most promising organic molecule may

  2. Nonlinear acoustics and honeycomb materials

    Science.gov (United States)

    Thompson, D. O.

    2012-05-01

    The scope of research activity that Bruce Thompson embraced was very large. In this talk three different research topics that the author shared with Bruce are reviewed. They represent Bruce's introduction to NDE and include nonlinear acoustics, nondestructive measurements of adhesive bond strengths in honeycomb panels, and studies of flexural wave dispersion in honeycomb materials. In the first of these, four harmonics of a 30 Mhz finite amplitude wave were measured for both fused silica and aluminum single crystals with varying lengths and amounts of cold work using a capacity microphone with heterodyne receiver with a flat frequency response from 30 to 250 Mhz. The results for fused silica with no dislocation structure could be described by a model due to Fubini, originally developed for gases, that depends upon only the second and third order elastic constants and not the fourth and higher order constants. The same was not true for the aluminum with dislocation structures. These results raised some questions about models for harmonic generation in materials with dislocations. In the second topic, experiments were made to determine the adhesive bond strengths of honeycomb panels using the vibrational response of the panels (Chladni figures). The results showed that both the damping characteristics of panel vibrations as a whole and velocity of propagation of elastic waves that travel along the surface and sample the bondline can be correlated with destructively determined bond strengths. Finally, the phase velocity of flexural waves traveling along a 1-inch honeycomb sandwich panel was determined from 170 Hz to 50 Khz, ranging from 2.2×104 cm/sec at the low end to 1.18×105 cm/sec at 40 Khz. The dispersion arises from the finite thickness of the panel and agreed with the results of continuum models for the honeycomb. Above 40 Khz, this was not the case. The paper concludes with a tribute to Bruce for his many wonderful contributions and lessons beyond his

  3. Probing hysteretic elasticity in weakly nonlinear materials

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Paul A [Los Alamos National Laboratory; Haupert, Sylvain [UPMC UNIV PARIS; Renaud, Guillaume [UPMC UNIV PARIS; Riviere, Jacques [UPMC UNIV PARIS; Talmant, Maryline [UPMC UNIV PARIS; Laugier, Pascal [UPMC UNIV PARIS

    2010-12-07

    Our work is aimed at assessing the elastic and dissipative hysteretic nonlinear parameters' repeatability (precision) using several classes of materials with weak, intermediate and high nonlinear properties. In this contribution, we describe an optimized Nonlinear Resonant Ultrasound Spectroscopy (NRUS) measuring and data processing protocol applied to small samples. The protocol is used to eliminate the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic elastic nonlinearity. As an example, in our experiments, we identified external temperature fluctuation as a primary source of material resonance frequency and elastic modulus variation. A variation of 0.1 C produced a frequency variation of 0.01 %, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to eliminate environmental effects, the variation in f{sub 0} (the elastically linear resonance frequency proportional to modulus) is fit with the appropriate function, and that function is used to correct the NRUS calculation of nonlinear parameters. With our correction procedure, we measured relative resonant frequency shifts of 10{sup -5} , which are below 10{sup -4}, often considered the limit to NRUS sensitivity under common experimental conditions. Our results show that the procedure is an alternative to the stringent control of temperature often applied. Applying the approach, we report nonlinear parameters for several materials, some with very small nonclassical nonlinearity. The approach has broad application to NRUS and other Nonlinear Elastic Wave Spectroscopy approaches.

  4. Modulational instability in periodic quadratic nonlinear materials

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole

    2001-01-01

    We investigate the modulational instability of plane waves in quadratic nonlinear materials with linear and nonlinear quasi-phase-matching gratings. Exact Floquet calculations, confirmed by numerical simulations, show that the periodicity can drastically alter the gain spectrum but never complete...

  5. Development of Organic Nonlinear Optical Materials

    Science.gov (United States)

    1992-10-22

    10 SOVRCE Of FUNO#NG NUM#E*S DM J .j PROGRAM PR0jECT TA5. ~ *0. I1I TITLE &Vila* So.Ivety ClaUMC400NJ Development of Organic NonLinear Optical Materials (U...0102-LF-014-6603 UNCLASSIFIED (U) AFOSR Contract: F4962040-C 0097 FINAL REPORT Development of Organic Nonlinear Optical Materials by J. Sounnk IL

  6. Mesoscale Engineering of Nanocomposite Nonlinear Optical Materials

    Energy Technology Data Exchange (ETDEWEB)

    Afonso, C.N.; Feldman, L.C.; Gonella, F.; Haglund, R.F.; Luepke, G.; Magruder, R.H.; Mazzoldi, P.; Osborne, D.H.; Solis, J.; Zuhr, R.A.

    1999-11-01

    Complex nonlinear optical materials comprising elemental, compound or alloy quantum dots embedded in appropriate dielectric or semiconducting hosts may be suitable for deployment in photonic devices. Ion implantation, ion exchange followed by ion implantation, and pulsed laser deposition have ail been used to synthesize these materials. However, the correlation between the parameters of energetic-beam synthesis and the nonlinear optical properties is still very rudimentary when one starts to ask what is happening at nanoscale dimensions. Systems integration of complex nonlinear optical materials requires that the mesoscale materials science be well understood within the context of device structures. We discuss the effects of beam energy and energy density on quantum-dot size and spatial distribution, thermal conductivity, quantum-dot composition, crystallinity and defects - and, in turn, on the third-order optical susceptibility of the composite material. Examples from recent work in our laboratories are used to illustrate these effects.

  7. Nonlinear System Identification and Behavioral Modeling

    CERN Document Server

    Huq, Kazi Mohammed Saidul; Kabir, A F M Sultanul

    2010-01-01

    The problem of determining a mathematical model for an unknown system by observing its input-output data pair is generally referred to as system identification. A behavioral model reproduces the required behavior of the original analyzed system, such as there is a one-to-one correspondence between the behavior of the original system and the simulated system. This paper presents nonlinear system identification and behavioral modeling using a work assignment.

  8. Geometric and material nonlinear analysis of tensegrity structures

    Institute of Scientific and Technical Information of China (English)

    Hoang Chi Tran; Jaehong Lee

    2011-01-01

    A numerical method is presented for the large deflection in elastic analysis of tensegrity structures including both geometric and material nonlinearities.The geometric nonlinearity is considered based on both total Lagrangian and updated Lagrangian formulations,while the material nonlinearity is treated through elastoplastic stressstrain relationship.The nonlinear equilibrium equations are solved using an incremental-iterative scheme in conjunction with the modified Newton-Raphson method.A computer program is developed to predict the mechanical responses of tensegrity systems under tensile,compressive and flexural loadings.Numerical results obtained are compared with those reported in the literature to demonstrate the accuracy and efficiency of the proposed program.The flexural behavior of the double layer quadruplex tensegrity grid is sufficiently good for lightweight large-span structural applications.On the other hand,its bending strength capacity is not sensitive to the self-stress level.

  9. Laser and nonlinear optical materials

    Energy Technology Data Exchange (ETDEWEB)

    De Shazer, L.G.

    1986-01-01

    This book contains 21 papers. Some of the titles are: Frequency conversion materials from a device perspective; Recent developments in area; Recent developments in barium borate; Growth of laser crystals at Airtron; Crystal growth and the future of solid state lasers; Faraday rotator materials for laser systems; and Mechanical properties of single crystal ceramics.

  10. On the determination of missing boundary data for solids with nonlinear material behaviors, using displacement fields measured on a part of their boundaries

    Science.gov (United States)

    Andrieux, Stéphane; Baranger, Thouraya N.

    2016-12-01

    The paper is devoted to the derivation of a numerical method for expanding available mechanical fields (stress vector and displacements) on a part of the boundary of a solid into its interior and up to unreachable parts of its boundary (with possibly internal surfaces). This expansion enables various identification or inverse problems to be solved in mechanics. The method is based on the solution of a nonlinear elliptic Cauchy problem because the mechanical behavior of the solid is considered as nonlinear (hyperelastic or elastoplastic medium). Advantage is taken of the assumption of convexity of the potentials used for modeling the constitutive equation, encompassing previous work by the authors for linear elastic solids, in order to derive an appropriate error functional. Two illustrations are given in order to evaluate the overall efficiency of the proposed method within the framework of small strains and isothermal transformation.

  11. Nonlinear Dynamics of Structures with Material Degradation

    Science.gov (United States)

    Soltani, P.; Wagg, D. J.; Pinna, C.; Whear, R.; Briody, C.

    2016-09-01

    Structures usually experience deterioration during their working life. Oxidation, corrosion, UV exposure, and thermo-mechanical fatigue are some of the most well-known mechanisms that cause degradation. The phenomenon gradually changes structural properties and dynamic behaviour over their lifetime, and can be more problematic and challenging in the presence of nonlinearity. In this paper, we study how the dynamic behaviour of a nonlinear system changes as the thermal environment causes certain parameters to vary. To this end, a nonlinear lumped mass modal model is considered and defined under harmonic external force. Temperature dependent material functions, formulated from empirical test data, are added into the model. Using these functions, bifurcation parameters are defined and the corresponding nonlinear responses are observed by numerical continuation. A comparison between the results gives a preliminary insight into how temperature induced properties affects the dynamic response and highlights changes in stability conditions of the structure.

  12. Geometrically nonlinear behavior of piezoelectric laminated plates

    Science.gov (United States)

    Rabinovitch, Oded

    2005-08-01

    The geometrically nonlinear behavior of piezo-laminated plates actuated with isotropic or anisotropic piezoelectric layers is analytically investigated. The analytical model is derived using the variational principle of virtual work along with the lamination and plate theories, the von Karman large displacement and moderate rotation kinematic relations, and the anisotropic piezoelectric constitutive laws. A solution strategy that combines the approach of the method of lines, the advantages of the finite element concept, and the variational formulation is developed. This approach yields a set of nonlinear ordinary differential equations with nonlinear boundary conditions, which are solved using the multiple-shooting method. Convergence and verification of the model are examined through comparison with linear and nonlinear results of other approximation methods. The nonlinear response of two active plate structures is investigated numerically. The first plate is actuated in bending using monolithic piezoceramic layers and the second one is actuated in twist using macro-fiber composites. The results quantitatively reveal the complicated in-plane stress state associated with the piezoelectric actuation and the geometrically nonlinear coupling of the in-plane and out-of-plane responses of the plate. The influence of the nonlinear effects ranges from significant stiffening in certain combinations of electrical loads and boundary conditions to amplifications of the induced deflections in others. The paper closes with a summary and conclusions.

  13. A nonlinear constitutive model for magnetostrictive materials

    Institute of Scientific and Technical Information of China (English)

    Xin'en Liu; Xiaojing Zheng

    2005-01-01

    A general nonlinear constitutive model is proposed for magnetostrictive materials, based on the important physical fact that a nonlinear part of the elastic strain produced by a pre-stress is related to the magnetic domain rotation or movement and is responsible for the change of the maximum magnetostrictive strain with the pre-stress. To avoid the complicity of determining the tensor function describing the nonlinear elastic strain part, this paper proposes a simplified model by means of linearizing the nonlinear function.For the convenience of engineering applications, the expressions of the 3-D (bulk), 2-D (film) and 1-D (rod) models are, respectively, given for an isotropic material and their applicable ranges are also discussed. By comparison with the experimental data of a Terfenol-D rod, it is found that the proposed model can accurately predict the magnetostrictive strain curves in low, moderate and high magnetic field regions for various compressive pre-stress levels. The numerical simulation further illustrates that, for either magnetostrictive rods or thin films, the proposed model can effectively describe the effects of the pre-stress or residual stress on the magnetization and magnetostrictive strain curves, while none of the known models can capture all of them. Therefore, the proposed model enjoys higher precision and wider applicability than the previous models, especially in the region of the high field.

  14. Nonlinear Electromagnetic Interactions in Energetic Materials

    CERN Document Server

    Wood, M A; Moore, D S

    2016-01-01

    We study the scattering of electromagnetic waves in anisotropic energetic materials. Nonlinear light-matter interactions in molecular crystals result in frequency-conversion and polarization changes. Applied electromagnetic fields of moderate intensity can induce these nonlinear effects without triggering chemical decomposition, offering a mechanism for non-ionizing identification of explosives. We use molecular dynamics simulations to compute such two-dimensional Raman spectra in the terahertz range for planar slabs made of PETN and ammonium nitrate. We discuss third-harmonic generation and polarization-conversion processes in such materials. These observed far-field spectral features of the reflected or transmitted light may serve as an alternative tool for stand-off explosive detection.

  15. On the prediction of stress relaxation from known creep of nonlinear materials

    Energy Technology Data Exchange (ETDEWEB)

    Touati, D.; Cederbaum, G. [Ben-Gurion Univ. of the Negev, Beer Sheva (Israel)

    1997-04-01

    A method to predict the nonlinear relaxation behavior from creep experiments of nonlinear viscoelastic materials is presented. It is shown that for given nonlinear creep properties, and creep compliance represented by the Prony series, the Schapery creep model can be transformed into a set of first order nonlinear equations. The solution of these equations enables the obtaining of the nonlinear stress relaxation curves. The strain-dependent constitutive equation can then be constructed for a given nonlinear viscoelastic model, as needed for engineering applications. A comparison example of the calculated stress relaxation curves, with test data for polyurethane demonstrates the very good accuracy of the proposed method.

  16. MACROSCOPIC STRAIN POTENTIALS IN NONLINEAR POROUS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    刘熠; 黄筑平

    2003-01-01

    By taking a hollow sphere as a representative volume element (RVE), the macroscopic strain potentials of porous materials with power-law incompressible matrix are studied in this paper.According to the principles of the minimum potential energy in nonlinear elasticity and the variational procedure, static admissible stress fields and kinematic admissible displacement fields are constructed,and hence the upper and the lower bounds of the macroscopic strain potential are obtained. The bounds given in the present paper differ so slightly that they both provide perfect approximations of the exact strain potential of the studied porous materials. It is also found that the upper bound proposed by previous authors is much higher than the present one, and the lower bounds given by Cocks is much lower. Moreover, the present calculation is also compared with the variational lower bound of Ponte Castafneda for statistically isotropic porous materials. Finally, the validity of the hollow spherical RVE for the studied nonlinear porous material is discussed by the difference between the present numerical results and the Cocks bound.

  17. Nonlinear behavior of the tarka flute's distinctive sounds

    Science.gov (United States)

    Gérard, Arnaud; Yapu-Quispe, Luis; Sakuma, Sachiko; Ghezzi, Flavio; Ramírez-Ávila, Gonzalo Marcelo

    2016-09-01

    The Andean tarka flute generates multiphonic sounds. Using spectral techniques, we verify two distinctive musical behaviors and the nonlinear nature of the tarka. Through nonlinear time series analysis, we determine chaotic and hyperchaotic behavior. Experimentally, we observe that by increasing the blow pressure on different fingerings, peculiar changes from linear to nonlinear patterns are produced, leading ultimately to quenching.

  18. Role of the metal cation types around VO4 groups on the nonlinear optical behavior of materials: experimental and theoretical analysis.

    Science.gov (United States)

    Su, Xin; Yang, Zhihua; Han, Guopeng; Wang, Ying; Wen, Ming; Pan, Shilie

    2016-09-28

    In order to explore new NLO crystals with superior performances, it is greatly desirable to understand the intrinsic relationship between the macroscopic optical properties and microscopic structural features in crystals. A novel mechanism for nonlinear optical (NLO) effects of vanadate crystals, Li3VO4, KCd4(VO4)3 and Ca3(VO4)2 with distorted (VO4)(3-) groups, has been investigated. Experiments related to the synthesis and structures were determined. In addition, infrared and UV-Vis-NIR diffuse reflectance spectroscopy, as well as electronic band structure calculations, were performed on the reported materials. A comprehensive analysis for the structure-property relationship is given by combining the experimental measurements, the electronic structure calculations and the SHG-weighted electron density to the linear and NLO properties. It was found that the contribution of the (VO4)(3-) anionic group to the second harmonic generation (SHG) response was the dominant anionic group, which plays a vital role to the SHG effects in Li3VO4, KCd4(VO4)3 and Ca3(VO4)2. It was also concluded that the metal cation types and coordination around VO4 groups, the distorted and parallel oriented VO4 tetrahedron decided the SHG coefficient values.

  19. Non-linear Behavior of Curved Sandwich Panels

    DEFF Research Database (Denmark)

    Berggreen, Carl Christian; Jolma, P.; Karjalainen, J. P.;

    2003-01-01

    In this paper the non-linear behavior of curved sandwich panels is investigated both numerically and experimentally. Focus is on various aspects of finite element modeling and calculation procedures. A simply supported, singly curved, CFRP/PVC sandwich panel is analyzed under uniform pressure load...... and results are compared to test data. A novel test arrangement utilizing a water filled cushion to create the uniform pressure load on curved panel specimen is used to obtain the experimental data. The panel is modeled with three different commercial finite element codes. Two implicit and one explicit code...... are used with various element types, modeling approaches and material models. The results show that the theoretical and experimental methods generally show fair agreement in panel non-linear behavior before collapse. It is also shown that special attention to detail has to be taken, because the predicted...

  20. Analysis of nonlinear elastic behavior in miniature pneumatic artificial muscles

    Science.gov (United States)

    Hocking, Erica G.; Wereley, Norman M.

    2013-01-01

    Pneumatic artificial muscles (PAMs) are well known for their excellent actuator characteristics, including high specific work, specific power, and power density. Recent research has focused on miniaturizing this pneumatic actuator technology in order to develop PAMs for use in small-scale mechanical systems, such as those found in robotic or aerospace applications. The first step in implementing these miniature PAMs was to design and characterize the actuator. To that end, this study presents the manufacturing process, experimental characterization, and analytical modeling of PAMs with millimeter-scale diameters. A fabrication method was developed to consistently produce low-cost, high performance, miniature PAMs using commercially available materials. The quasi-static behavior of these PAMs was determined through experimentation on a single actuator with an active length of 39.16 mm (1.54 in) and a diameter of 4.13 mm (0.1625 in). Testing revealed the PAM’s full evolution of force with displacement for operating pressures ranging from 207 to 552 kPa (30-80 psi in 10 psi increments), as well as the blocked force and free contraction at each pressure. Three key nonlinear phenomena were observed: nonlinear PAM stiffness, hysteresis of the force versus displacement response for a given pressure, and a pressure deadband. To address the analysis of the nonlinear response of these miniature PAMs, a nonlinear stress versus strain model, a hysteresis model, and a pressure bias are introduced into a previously developed force balance analysis. Parameters of these nonlinear model refinements are identified from the measured force versus displacement data. This improved nonlinear force balance model is shown to capture the full actuation behavior of the miniature PAMs at each operating pressure and reconstruct miniature PAM response with much more accuracy than previously possible.

  1. Complex behavior in chains of nonlinear oscillators

    Science.gov (United States)

    Alonso, Leandro M.

    2017-06-01

    This article outlines sufficient conditions under which a one-dimensional chain of identical nonlinear oscillators can display complex spatio-temporal behavior. The units are described by phase equations and consist of excitable oscillators. The interactions are local and the network is poised to a critical state by balancing excitation and inhibition locally. The results presented here suggest that in networks composed of many oscillatory units with local interactions, excitability together with balanced interactions is sufficient to give rise to complex emergent features. For values of the parameters where complex behavior occurs, the system also displays a high-dimensional bifurcation where an exponentially large number of equilibria are borne in pairs out of multiple saddle-node bifurcations.

  2. Eliminating material constraints for nonlinearity with plasmonic metamaterials

    Science.gov (United States)

    Neira, Andres D.; Olivier, Nicolas; Nasir, Mazhar E.; Dickson, Wayne; Wurtz, Gregory A.; Zayats, Anatoly V.

    2015-01-01

    Nonlinear optical materials comprise the foundation of modern photonics, offering functionalities ranging from ultrafast lasers to optical switching, harmonic and soliton generation. Optical nonlinearities are typically strong near the electronic resonances of a material and thus provide limited tuneability for practical use. Here we show that in plasmonic nanorod metamaterials, the Kerr-type nonlinearity is not limited by the nonlinear properties of the constituents. Compared with gold's nonlinearity, the measured nonlinear absorption and refraction demonstrate more than two orders of magnitude enhancement over a broad spectral range that can be engineered via geometrical parameters. Depending on the metamaterial's effective plasma frequency, either a focusing or defocusing nonlinearity is observed. The ability to obtain strong and fast optical nonlinearities in a given spectral range makes these metamaterials a flexible platform for the development of low-intensity nonlinear applications. PMID:26195182

  3. Laser And Nonlinear Optical Materials For Laser Remote Sensing

    Science.gov (United States)

    Barnes, Norman P.

    2005-01-01

    NASA remote sensing missions involving laser systems and their economic impact are outlined. Potential remote sensing missions include: green house gasses, tropospheric winds, ozone, water vapor, and ice cap thickness. Systems to perform these measurements use lanthanide series lasers and nonlinear devices including second harmonic generators and parametric oscillators. Demands these missions place on the laser and nonlinear optical materials are discussed from a materials point of view. Methods of designing new laser and nonlinear optical materials to meet these demands are presented.

  4. Organosilicon Polymeric Nonlinear Optical Materials for Optical Switching and Modulation

    Science.gov (United States)

    1994-02-28

    Organosilicon Polymeric Nonlinear Optical Materials for Optical C: F49620-93-C-0039 Switching and Modulation 6. AUTHOR(S) Mr. Sandip K. Sengupta, Dr...D FINAL REPORT for Organosilicon Polymeric Nonlinear Optical Materials for Optical Switching and Modulation Prepared for: USAF, AFMC (AFOSR) Air Force...34Organosilicon Polymeric Nonlinear Optical Materials for Optical Switching and Modulation," contract number F49620-93-C-0039. The work has been performed by Dr

  5. Characterizaticr of Solid State Laser and Nonlinear Optical Materials.

    Science.gov (United States)

    1995-02-02

    materials useful in the different methods for obtaining frequency agility: narrow line emitters with multiple lasing channels and nonlinear optical materials . In...codoped with two or more rare earth ions were studied and computers models developed to explain their spectral dynamics. The nonlinear optical materials investigated

  6. Unsymmetrical squaraines for nonlinear optical materials

    Science.gov (United States)

    Marder, Seth R. (Inventor); Chen, Chin-Ti (Inventor); Cheng, Lap-Tak (Inventor)

    1996-01-01

    Compositions for use in non-linear optical devices. The compositions have first molecular electronic hyperpolarizability (.beta.) either positive or negative in sign and therefore display second order non-linear optical properties when incorporated into non-linear optical devices.

  7. Measuring nonlinear behavior in time series data

    Science.gov (United States)

    Wai, Phoong Seuk; Ismail, Mohd Tahir

    2014-12-01

    Stationary Test is an important test in detect the time series behavior since financial and economic data series always have missing data, structural change as well as jumps or breaks in the data set. Moreover, stationary test is able to transform the nonlinear time series variable to become stationary by taking difference-stationary process or trend-stationary process. Two different types of hypothesis testing of stationary tests that are Augmented Dickey-Fuller (ADF) test and Kwiatkowski-Philips-Schmidt-Shin (KPSS) test are examine in this paper to describe the properties of the time series variables in financial model. Besides, Least Square method is used in Augmented Dickey-Fuller test to detect the changes of the series and Lagrange multiplier is used in Kwiatkowski-Philips-Schmidt-Shin test to examine the properties of oil price, gold price and Malaysia stock market. Moreover, Quandt-Andrews, Bai-Perron and Chow tests are also use to detect the existence of break in the data series. The monthly index data are ranging from December 1989 until May 2012. Result is shown that these three series exhibit nonlinear properties but are able to transform to stationary series after taking first difference process.

  8. Nonlinear behaviors of parity-time-symmetric lasers

    CERN Document Server

    Yang, Jianke

    2016-01-01

    We propose a time-dependent partial differential equation model to investigate the dynamical behavior of the parity-time (PT) symmetric laser during the nonlinear stage of its operation. This model incorporates physical effects such as the refractive index distribution, dispersion, material loss, nonlinear gain saturation and self-phase modulation. We show that when the loss is weak, multiple stable steady states and time-periodic states of light exist above the lasing threshold, rendering the laser multi-mode. However, when the loss is strong, only a single stable steady state of broken PT symmetry exists for a wide range of the gain amplitude, rendering the laser single-mode. These results reveal the important role the loss plays in maintaining the single-mode operation of PT lasers.

  9. Analysis of a Beam Made of Physical Nonlinear Material on Nonlinear Elastic Foundation under a Moving Concentrated Load

    Directory of Open Access Journals (Sweden)

    E. Mardani

    2008-01-01

    Full Text Available A prismatic beam made of a behaviorally nonlinear material was analyzed under a concentrated load moving with a known velocity on a nonlinear elastic foundation with a reaction the vibration equation of motion was derived using Hamilton principle and Euler Lagrange equation. The amplitude of vibration, circular frequency, bending moment, stress and deflection of the beam can be calculated by the presented solution. Considering the response of the beam, in the sense of its resonance, it was found that there is no critical velocity when the behavior of the beam and foundation material is assumed to be physically nonlinear and there are finite values for the deflection, stress and bending moment of the beam when

  10. Materials Behavior Research Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The purpose is to evaluate mechanical properties of materials including metals, intermetallics, metal-matrix composites, and ceramic-matrix composites under typical...

  11. Laser and nonlinear optical materials: SPIE volume 681

    Energy Technology Data Exchange (ETDEWEB)

    De Shazer, L.G.

    1987-01-01

    This book contains papers arranged under the following session headings: Nonlinear optical crystals; Laser host crystals; Electro-optic and magneto-optic materials; and Characterization of optical materials.

  12. Investigating nonlinear distortion in the photopolymer materials

    Science.gov (United States)

    Malallah, Ra'ed; Cassidy, Derek; Muniraj, Inbarasan; Zhao, Liang; Ryle, James P.; Sheridan, John T.

    2017-05-01

    Propagation and diffraction of a light beam through nonlinear materials are effectively compensated by the effect of selftrapping. The laser beam propagating through photo-sensitive polymer PVA/AA can generate a waveguide of higher refractive index in direction of the light propagation. In order to investigate this phenomenon occurring in light-sensitive photopolymer media, the behaviour of a single light beam focused on the front surface of photopolymer bulk is investigated. As part of this work the self-bending of parallel beams separated in spaces during self-writing waveguides are studied. It is shown that there is strong correlation between the intensity of the input beams and their separation distance and the resulting deformation of waveguide trajectory during channels formation. This self-channeling can be modelled numerically using a three-dimension model to describe what takes place inside the volume of a photopolymer media. Corresponding numerical simulations show good agreement with experimental observations, which confirm the validity of the numerical model that was used to simulate these experiments.

  13. Dynamical Behavior of Nonlinear Viscoelastic Timoshenko Beams with Damage on a Viscoelastic Foundation

    Institute of Scientific and Technical Information of China (English)

    盛冬发; 张燕; 程昌钧

    2004-01-01

    Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams with large deflections, the nonlinear equations governing dynamical behavior of Timoshenko beams with damage on viscoelastic foundation were firstly derived. By using the Galerkin method in spatial domain, the nonlinear integro-partial differential equations were transformed into a set of integro-ordinary differential equations. The numerical methods in nonlinear dynamical systems, such as the phase-trajectory diagram, Poincare section and bifurcation figure, were used to solve the simplified systems of equations. It could be seen that simplified dynamical systems possess the plenty of nonlinear dynamical properties. The influence of load and material parameters on the dynamic behavior of nonlinear system were investigated in detail.

  14. Analysis of nonlinear behavior of loudspeakers using the instantaneous frequency

    DEFF Research Database (Denmark)

    Huang, Hai; Jacobsen, Finn

    2003-01-01

    It is well know that the weakest link in a sound reproduction chain is the loudspeaker. The most significant effect on the sound quality is nonlinear distortion of loudspeakers. Many methods are applied to analyze the nonlinear distortion of loudspeakers. Almost all of the methods are based...... on the Fourier transform. In this work, a new method using the instantaneous frequency is introduced for describing and characterizing loudspeaker nonlinearities. First, numerical integration is applied to simulate the nonlinearities of loudspeakers caused by two nonlinear parameters, force factor and stiffness......, separately. Then, a practical loudspeaker is used in an experiment and its nonlinear characteristics are analyzed with the instantaneous frequency. The results provide a clear physical interpretation of the nonlinearities of loudspeakers and will be useful for understanding the nonlinear behavior...

  15. All-optical signal processing in quadratic nonlinear materials

    DEFF Research Database (Denmark)

    Johansen, Steffen Kjær

    2002-01-01

    of materials with a second order nonlinearity, the so-called X(2) materials, is faster and stronger than that of more conventional materials with a cubic nonlinearity. The X(2) materials support spatial solitons consisting of two coupled components, the fundamental wave (FW) and its second harmonic (SH......). During this project the interaction between such spatial solitons has been investigated theoretically through perturbation theory and experimentally via numerical simulations. The outcome of this research isnew theoretical tools for quantitatively predicting the escape angle, i.e. the angle of incidence...... and exploitation of these cubic nonlinearities in two-period QPM wave-guides has been another area of investigation. Introducing the second period might make practical engineering of the nonlinearities possible. A major result is the discovery that cubic nonlinearities leads to an enhancement of the bandwidth...

  16. A nonlinear Schroedinger wave equation with linear quantum behavior

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Chris D.; Schlagheck, Peter; Martin, John; Vandewalle, Nicolas; Bastin, Thierry [Departement de Physique, University of Liege, 4000 Liege (Belgium)

    2014-07-01

    We show that a nonlinear Schroedinger wave equation can reproduce all the features of linear quantum mechanics. This nonlinear wave equation is obtained by exploring, in a uniform language, the transition from fully classical theory governed by a nonlinear classical wave equation to quantum theory. The classical wave equation includes a nonlinear classicality enforcing potential which when eliminated transforms the wave equation into the linear Schroedinger equation. We show that it is not necessary to completely cancel this nonlinearity to recover the linear behavior of quantum mechanics. Scaling the classicality enforcing potential is sufficient to have quantum-like features appear and is equivalent to scaling Planck's constant.

  17. Thioborates: potential nonlinear optical materials with rich structural chemistry.

    Science.gov (United States)

    Lian, Yu-Kun; Wu, Li-Ming; Chen, Ling

    2017-03-27

    Nonlinear optical (NLO) crystal materials with good performance are urgently needed. Various compounds have been explored to date. Metal chalcogenides and borates are common sources of potential NLO materials with desirable properties, particularly in the IR and UV regions, respectively. However, these two types of crystals have their specific drawbacks. Thioborates, as an emerging system, have unique advantages by combining the merits of borates and sulfides, i.e., the high laser damage thresholds and rich structural diversity of borates with large optical nonlinearity and the favorable transparency range of sulfides. However, only a limited number of thioborates are known. This paper summarizes the known thioborates according to structural motifs that range from zero-dimension to three-dimension, most of which are formed by sharing corners of the basic building units (BS3)(3-) and (BS4)(5-). Although nearly one-third of the known thioborates are noncentrosymmetric, most of their properties, especially their NLO behaviors, are unexplored. Further attempts and additional investigations are required with respect to design syntheses, property improvements and micro-mechanism studies.

  18. Chaotic behavior in nonlinear polarization dynamics

    Energy Technology Data Exchange (ETDEWEB)

    David, D.; Holm, D.D.; Tratnik, M.V. (Los Alamos National Lab., NM (USA))

    1989-01-01

    We analyze the problem of two counterpropagating optical laser beams in a slightly nonlinear medium from the point of view of Hamiltonian systems; the one-beam subproblem is also investigated as a special case. We are interested in these systems as integrable dynamical systems which undergo chaotic behavior under various types of perturbations. The phase space for the two-beam problem is C{sup 2} {times} C{sup 2} when we restricted the the regime of travelling-wave solutions. We use the method of reduction for Hamiltonian systems invariant under one-parameter symmetry groups to demonstrate that the phase space reduces to the two-sphere S{sup 2} and is therefore completely integrable. The phase portraits of the system are classified and we also determine the bifurcations that modify these portraits; some new degenerate bifurcations are presented in this context. Finally, we introduce various physically relevant perturbations and use the Melnikov method to prove that horseshoe chaos and Arnold diffusion occur as consequences of these perturbations. 10 refs., 7 figs., 1 tab.

  19. Viscoelastic behavior of rubbery materials

    CERN Document Server

    Roland, C M

    2011-01-01

    The gigantic size of polymer molecules makes them viscoelastic - their behavior changes depending on how fast and for how long the material is used. This book looks at the latest discoveries in the field from a fundamental molecular perspective, in order to guide the development of better and new applications for soft materials.

  20. Composite structures for the enhancement of nonlinear optical materials.

    Science.gov (United States)

    Neeves, A E; Birnboim, M H

    1988-12-01

    Calculations of the nonlinear optical behavior are developed for model composites consisting of nanospheres with a metallic core and a nonlinear shell suspended in a nonlinear medium. The concept for the enhancement of optical phase conjugation from all these nonlinear regions is that the optical field can be concentrated both inside and in the neighborhood of the metallic core, aided by surface-mediated plasmon resonance. Calculations for gold cores and aluminum cores indicate that phase-conjugate reflectivity enhancements of 10(8) may be possible.

  1. Tunable Optical Sources and Synthetic Nonlinear Media: Growth and Characterization of Nonlinear Optical Materials

    Science.gov (United States)

    1992-02-13

    niobate and absolute measurements of nonlinear optical coefficients of six different commonly used nonlinear optical materials. The refractometry data for...applied radiation and is now an established technology for Nd:YAG lasers. Optical parametric oscillation and amplification provide a method of generating...continuously tunable output -3- The relative advantages of nonlinear optical frequency conversion compared to other methods for the generation of near

  2. Mechanical behavior of emerging materials

    Directory of Open Access Journals (Sweden)

    Challapalli Suryanarayana

    2012-11-01

    Full Text Available Nanocrystalline and glassy materials, especially the bulk metallic glasses are of relatively recent origin and exhibit high strength, but lack sufficient plasticity. A clear understanding of the mechanical behavior of these novel materials is essential before these can be seriously considered for structural applications. A great deal of research has been conducted over the past couple of decades and a vast amount of data has been generated. Here, results on strength, ductility, and deformation behavior of these novel materials have been reviewed. Recent results have been highlighted and problems, wherever they exist, have been pointed out. New directions for enhancing the understanding of the mechanical behavior of these interesting materials have been suggested.

  3. Nonlinear electronic transport behavior in Indium Nitride

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Cloves G., E-mail: cloves@pucgoias.edu.br [Departamento de Fisica, Pontificia Universidade Catolica de Goias, CP 86, 74605-010 Goiania, Goias (Brazil)

    2012-11-15

    A theoretical study on the nonlinear transport of electrons and of the nonequilibrium temperature in n-doped Indium Nitride under influence of moderate to high electric fields (in this nonlinear domain) is presented. It is based on a nonlinear quantum kinetic theory which provides a description of the dissipative phenomena developing in the system. The electric current and the mobility in the steady state are obtained, and their dependence on the electric field strength and on the concentration (that is, a mobility dependent nonlinearly on field and concentration) is obtained and analyzed. -- Highlights: Black-Right-Pointing-Pointer We have reported on the topic of nonlinear transport (electron mobility) in n-doped InN. Black-Right-Pointing-Pointer The results evidence the presence of two distinctive regimes. Black-Right-Pointing-Pointer The dependence of the mobility on the electric field is manifested through of the relaxation times.

  4. Nonlinear Finite Strain Consolidation Analysis with Secondary Consolidation Behavior

    Directory of Open Access Journals (Sweden)

    Jieqing Huang

    2014-01-01

    Full Text Available This paper aims to analyze nonlinear finite strain consolidation with secondary consolidation behavior. On the basis of some assumptions about the secondary consolidation behavior, the continuity equation of pore water in Gibson’s consolidation theory is modified. Taking the nonlinear compressibility and nonlinear permeability of soils into consideration, the governing equation for finite strain consolidation analysis is derived. Based on the experimental data of Hangzhou soft clay samples, the new governing equation is solved with the finite element method. Afterwards, the calculation results of this new method and other two methods are compared. It can be found that Gibson’s method may underestimate the excess pore water pressure during primary consolidation. The new method which takes the secondary consolidation behavior, the nonlinear compressibility, and nonlinear permeability of soils into consideration can precisely estimate the settlement rate and the final settlement of Hangzhou soft clay sample.

  5. Molecular and crystal design of nonlinear optical organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Suponitsky, Kirill Yu; Antipin, Mikhail Yu [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow (Russian Federation); Timofeeva, Tatiana V [Department of Chemistry, New Mexico Highlands University (United States)

    2006-06-30

    The results of theoretical and experimental studies on the second-order molecular and crystal nonlinear optical susceptibilities of organic and several classes of organoelement compounds are summarised. Modern methods used in these studies are briefly characterised, their advantages and drawbacks are outlined as regards their application to the systematic search for efficient nonlinear optical materials. Recent achievements and the main challenges in the field are thoroughly discussed and an optimum algorithm of the design of such materials is proposed.

  6. Organic/Organometallic Hybrids as Broadband Nonlinear Transmission Materials

    Science.gov (United States)

    2010-06-01

    property correlation in organometallic complexes in order to develop broadband nonlinear transmission materials . To realize this goal, we have...platinum complexes and 10 zinc phthalocyanine derivatives provided by collaborators in China. From these studies, we have discovered that in order to...in the near-IR region still limited their application as broadband nonlinear absorbing materials . To solve this problem, two approaches were

  7. Theory of nonlinear elastic behavior in rock

    Energy Technology Data Exchange (ETDEWEB)

    McCall, K.R.

    1993-04-01

    We study plane wave propagation in an isotropic, homogeneous solid with cubic and quartic anharmonicity. Attenuation is introduced through use of a retarded displacement response. We develop a Green function technique to exhibit the solution for the displacement field as a systematic hierarchy in the nonlinear parameters. This solution is applied to three problems: propagation from monochromatic and broadband sources, and the shape of nonlinear stress curves.

  8. Theory of nonlinear elastic behavior in rock

    Energy Technology Data Exchange (ETDEWEB)

    McCall, K.R.

    1993-01-01

    We study plane wave propagation in an isotropic, homogeneous solid with cubic and quartic anharmonicity. Attenuation is introduced through use of a retarded displacement response. We develop a Green function technique to exhibit the solution for the displacement field as a systematic hierarchy in the nonlinear parameters. This solution is applied to three problems: propagation from monochromatic and broadband sources, and the shape of nonlinear stress curves.

  9. In situ nonlinear elastic behavior of soil observed by DAET

    Energy Technology Data Exchange (ETDEWEB)

    Larmat, Carene [Los Alamos National Laboratory; Renaud, Guillaume [Eramus Medical Center, Rotterdam, The Netherlands; Rutledge, James T. [EES-17: GEOPHYSICS; Lee, Richard C. [Los Alamos National Laboratory; Guyer, Robert A. [Los Alamos National Laboratory; Johnson, Paul A. [Los Alamos National Laboratory

    2012-07-05

    The key to safe design of critical facilities (strong ground motion in low velocity materials such as soils). Current approaches are predictions from measurements of the elastic non-linear properties of boreholes samples. Need for in-situ, local and complete determination of non-linear properties of soil, rock in response to high-strain motion.

  10. A Strategy for the Development of Macromolecular Nonlinear Optical Materials

    Science.gov (United States)

    1990-01-01

    obsolete. SECURITY CLASSIFICATION OF THIS PAGE STRATEGY FOR THE DEVELOPMENT OF MACROMOLECULAR NONLINEAR OPTICAL MATERIALS Braja K. Mandala , Jan-Chan...materials is significantly different from the conventional inorganic NLO materials. The extent of second order (quadratic) NLO effect such as second...is a criterion of paramount importance for a large second order electro-optic effect in organic materials 8 ,9 . The most common approach to obtain

  11. Design of advanced materials for linear and nonlinear dynamics

    DEFF Research Database (Denmark)

    Frandsen, Niels Morten Marslev

    The primary catalyst of this PhD project has been an ambition to design advanced materials and structural systems including, and possibly even exploiting, nonlinear phenomena such as nonlinear modal interaction leading to energy conversion between modes. An important prerequisite for efficient...... design is accurate and somewhat simple analysis tools, as well as a fundamental understanding of the physical phenomena responsible for the relevant effects. The emphasis of this work lies primarily in the investigation of various advanced material models, developing the necessary analytical tools...... to reveal the fundamental dynamic characteristics and thus the relevant design parameters.The thesis is built around the characterization of two one-dimensional, periodic material systems. The first is a nonlinear mass-spring chain with periodically varying material properties, representing a simple...

  12. Non-linear Constitutive Model for the Oligocarbonate Polyurethane Material

    Institute of Scientific and Technical Information of China (English)

    Marek Pawlikowski

    2014-01-01

    The polyurethane,which was the subject of the constitutive research presented in the paper,was based on oligocarbonate diols Desmophen C2100 produced by Bayer@.The constitutive modelling was performed with a view to applying the material as the inlay of intervertebral disc prostheses.The polyurethane was assumed to be non-linearly viscohyperelastic,isotropic and incompressible.The constitutive equation was derived from the postulated strain energy function.The elastic and rheological constants were identified on the basis of experimental tests,i.e.relaxation tests and monotonic uniaxial tests at two different strain rates,i.e.λ =0.1 min-1 and λ =1.0 min-1.The stiffness tensor was derived and introduced to Abaqus@finite element (FE) software in order to numerically validate the constitutive model.The results of the constants identification and numerical implementation show that the derived constitutive equation is fully adequate to model stress-strain behavior of the polyurethane material.

  13. Application of Novel Nonlinear Optical Materials to Optical Processing

    Science.gov (United States)

    Banerjee, Partha P.

    1999-01-01

    We describe wave mixing and interactions in nonlinear photorefractive polymers and disodium flourescein. Higher diffracted orders yielding forward phase conjugation can be generated in a two-wave mixing geometry in photorefractive polymers, and this higher order can be used for image edge enhancement and correlation. Four-wave mixing and phase conjugation is studied using nonlinear disodium floureschein, and the nature and properties of gratings written in this material are investigated.

  14. Dielectric and Elastic Characterization of Nonlinear Heterogeneous Materials

    Directory of Open Access Journals (Sweden)

    Stefano Giordano

    2009-09-01

    Full Text Available This review paper deals with the dielectric and elastic characterization of composite materials constituted by dispersions of nonlinear inclusions embedded in a linear matrix. The dielectric theory deals with pseudo-oriented particles shaped as ellipsoids of revolution: it means that we are dealing with mixtures of inclusions of arbitrary aspect ratio and arbitrary non-random orientational distributions. The analysis ranges from parallel spheroidal inclusions to completely random oriented inclusions. Each ellipsoidal inclusion is made of an isotropic dielectric material described by means of the so-called Kerr nonlinear relation. On the other hand, the nonlinear elastic characterization takes into consideration a dispersion of nonlinear (spherical or cylindrical inhomogeneities. Both phases are considered isotropic (actually it means polycrystalline or amorphous solids. Under the simplifying hypotheses of small deformation for the material body and of small volume fraction of the embedded phase, we describe a theory for obtaining the linear and nonlinear elastic properties (bulk and shear moduli and Landau coefficients of the overall material.

  15. Nonlinear mechanics of soft fibrous materials

    CERN Document Server

    Ogden, Raymond

    2015-01-01

    The book presents a state-of-the-art overview of the fundamental theories, established models and ongoing research related to the modeling of these materials. Two approaches are conventionally used to develop constitutive relations for highly deformable fibrous materials. According to the phenomenological approach, a strain energy density function can be defined in terms of strain invariants. The other approach is based on kinetic theories, which treats a fibrous material as a randomly oriented inter-tangled network of long molecular chains bridged by permanent and temporary junctions. At the micro-level, these are associated with chemical crosslinks and active entanglements, respectively. The papers include carefully crafted overviews of the fundamental formulation of the three-dimensional theory from several points of view, and address their equivalences and differences. Also included are solutions to boundary-value problems which are amenable to experimental verification. A further aspect is the elasticity...

  16. Multiscale Study of the Nonlinear Behavior of Heterogeneous Clayey Rocks Based on the FFT Method

    Science.gov (United States)

    Jiang, Tao; Xu, Weiya; Shao, Jianfu

    2015-03-01

    A multiscale model based on the fast Fourier transform (FFT) is applied to study the nonlinear mechanical behavior of Callovo-Oxfordian (COx) argillite, a typical heterogeneous clayey rocks. COx argillite is modeled as a three-phase composite with a clay matrix and two types of mineral inclusions. The macroscopic mechanical behavior of argillite samples with different mineralogical compositions are satisfactorily predicted by unified local constitutive models and material parameters. Moreover, the numerical implementation of the FFT-based nonlinear homogenization is easier than direct homogenization, such as the FEM-based homogenization, because it automatically satisfies the periodic boundary condition.

  17. Organic materials with nonlinear optical properties

    Science.gov (United States)

    Stupp, Samuel I.; Son, Sehwan; Lin, Hong-Cheu

    1995-01-01

    The present invention is directed to organic materials that have the ability to double or triple the frequency of light that is directed through the materials. Particularly, the present invention is directed to the compound 4-[4-(2R)-2-cyano-7-(4'-pentyloxy-4-biphenylcarbonyloxy)phenylheptylidene) phenylcarbonyloxy]benzaldehyde, which can double the frequency of light that is directed through the compound. The invention is also directed to the compound (12-hydroxy-5,7-dodecadiynyl) 4'-[(4'-pentyloxy-4-biphenyl)carbonyloxy]-4-biphenylcarboxylate, and its polymeric form. The polymeric form can triple the frequency of light directed through it.

  18. Analytical Modeling of Hard-Coating Cantilever Composite Plate considering the Material Nonlinearity of Hard Coating

    Directory of Open Access Journals (Sweden)

    Wei Sun

    2015-01-01

    Full Text Available Due to the material nonlinearity of hard coating, the coated structure produces the nonlinear dynamical behaviors of variable stiffness and damping, which make the modeling of hard-coating composite structure become a challenging task. In this study, the polynomial was adopted to characterize this material nonlinearity and an analytical modeling method was developed for the hard-coating composite plate. Firstly, to relate the hard-coating material parameters obtained by test and the analytical model, the expression of equivalent strain of composite plate was derived. Then, the analytical model of hard-coating composite plate was created by energy method considering the material nonlinearity of hard coating. Next, using the Newton-Raphson method to solve the vibration response and resonant frequencies of composite plate and a specific calculation procedure was also proposed. Finally, a cantilever plate coated with MgO + Al2O3 hard coating was chosen as study case; the vibration response and resonant frequencies of composite plate were calculated using the proposed method. The calculation results were compared with the experiment and general linear calculation, and the correctness of the created model was verified. The study shows the proposed method can still maintain an acceptable precision when the material nonlinearity of hard coating is stronger.

  19. Materials for Nonlinear Optics Chemical Perspectives

    Science.gov (United States)

    1991-01-01

    introduced into LB muldilayers built from 1/1 mixtures with an amphiphilic cyclodextrin . The polyenic chains are again perpendicular to the substrate...molecules in inorganic matrices. The encapsulated molecules can be used to induce new optical properties in the material or to probe the changes at the...glass are discussed here. First, laser dyes including rhodamines and coumarins are encapsulated . The resulting doped gel-glasses exhibit optical gain

  20. Structural analysis of composite wind turbine blades nonlinear mechanics and finite element models with material damping

    CERN Document Server

    Chortis, Dimitris I

    2013-01-01

    This book concerns the development of novel finite elements for the structural analysis of composite beams and blades. The introduction of material damping is also an important aspect of composite structures and it is presented here in terms of their static and dynamic behavior. The book thoroughly presents a new shear beam finite element, which entails new blade section mechanics, capable of predicting structural blade coupling due to composite coupling and/or internal section geometry. Theoretical background is further expanded towards the inclusion of nonlinear structural blade models and damping mechanics for composite structures. The models effectively include geometrically nonlinear terms due to large displacements and rotations, improve the modeling accuracy of very large flexible blades, and enable the modeling of rotational stiffening and buckling, as well as, nonlinear structural coupling. Validation simulations on specimen level study the geometric nonlinearities effect on the modal frequencies and...

  1. A non-linear homogeneous model for bone-like materials under compressive load.

    Science.gov (United States)

    Mengoni, M; Voide, R; de Bien, C; Freichels, H; Jérôme, C; Léonard, A; Toye, D; Müller, R; van Lenthe, G H; Ponthot, J P

    2012-02-01

    Finite element (FE) models accurately compute the mechanical response of bone and bone-like materials when the models include their detailed microstructure. In order to simulate non-linear behavior, which currently is only feasible at the expense of extremely high computational costs, coarser models can be used if the local morphology has been linked to the apparent mechanical behavior. The aim of this paper is to implement and validate such a constitutive law. This law is able to capture the non-linear structural behavior of bone-like materials through the use of fabric tensors. It also allows for irreversible strains using an elastoplastic material model incorporating hardening. These features are expressed in a constitutive law based on the anisotropic continuum damage theory coupled with isotropic elastoplasticity in a finite strain framework. This material model was implemented into metafor (LTAS-MNNL, University of Liège, Belgium), a non-linear FE software. The implementation was validated against experimental data of cylindrical samples subjected to compression. Three materials with bone-like microstructure were tested: aluminum foams of variable density (ERG, Oakland, CA, USA), polylactic acid foam (CERM, University of Liège, Liège, Belgium), and cancellous bone tissue of a deer antler (Faculty of Veterinary Medicine, University of Liège, Liège, Belgium).

  2. Detection of electromagnetic radiation using nonlinear materials

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Harold Y.; Liu, Mengkun; Averitt, Richard D.; Nelson, Keith A.; Sternbach, Aaron; Fan, Kebin

    2016-06-14

    An apparatus for detecting electromagnetic radiation within a target frequency range is provided. The apparatus includes a substrate and one or more resonator structures disposed on the substrate. The substrate can be a dielectric or semiconductor material. Each of the one or more resonator structures has at least one dimension that is less than the wavelength of target electromagnetic radiation within the target frequency range, and each of the resonator structures includes at least two conductive structures separated by a spacing. Charge carriers are induced in the substrate near the spacing when the resonator structures are exposed to the target electromagnetic radiation. A measure of the change in conductivity of the substrate due to the induced charge carriers provides an indication of the presence of the target electromagnetic radiation.

  3. Modeling of Z-scan characteristics for one-dimensional nonlinear photonic bandgap materials.

    Science.gov (United States)

    Chen, Shuqi; Zang, Weiping; Schülzgen, Axel; Liu, Xin; Tian, Jianguo; Moloney, Jerome V; Peyghambarian, Nasser

    2009-12-01

    We propose a Z-scan theory for one-dimensional nonlinear photonic bandgap materials. The Z-scan characteristics for this material are analyzed. Results show that the Z-scan curves for photonic bandgap materials with nonlinear refraction are similar to those of uniform materials exhibiting both nonlinear refraction and nonlinear absorption simultaneously. Effects of nonlinear absorption on reflected and transmitted Z-scan results are also discussed.

  4. All-optical switching in subwavelength metallic grating structure containing nonlinear optical materials.

    Science.gov (United States)

    Min, Changjun; Wang, Pei; Chen, Chunchong; Deng, Yan; Lu, Yonghua; Ming, Hai; Ning, Tingyin; Zhou, Yueliang; Yang, Guozhen

    2008-04-15

    All-optical switching based on a subwavelength metallic grating structure containing nonlinear optical materials has been proposed and numerically investigated. Metal-dielectric composite material is used in the switching for its larger third-order nonlinear susceptibility (approximately 10(-7)esu) and ultrafast response properties. The calculated dependence of the signal light intensity on the pump light intensity shows a bistable behavior, which results in a significant switch effect. It rests on a surface plasmon's enhanced intensity-dependent change of the effective dielectric constant of Kerr nonlinear media, corresponding to a transition of the far-field transmission from a low- to high-transmission state. The study of this switching structure shows great advantages of smaller size, lower requirement of pump light intensity, and shorter switching time at approximately the picosecond level.

  5. Numerical simulation of mechanical behavior of composite materials

    CERN Document Server

    Oller, Sergio

    2014-01-01

    An original mechanical formulation to treat nonlinear orthotropic behavior of composite materials is presented in this book. It also examines different formulations that allow us to evaluate the behavior of composite materials through the composition of its components, obtaining a new composite material. Also two multiple scale homogenization methods are given, one based on the analytical study of the cells (Ad-hoc homogenization), and other one, more general based on the finite element procedure applied on the macro scale (upper-scale) and in the micro scale (sub-scale). A very general formulation to simulate the mechanical behavior for traditional composite structures (plywood, reinforced concrete, masonry, etc.), as well as the new composite materials reinforced with long and short fibers, nanotubes, etc., are also shown in this work. Typical phenomena occurring in composite materials are also described in this work, including fiber-matrix debounding, local buckling of fibers and its coupling with the over...

  6. Effective Behavior of Composite Materials.

    Science.gov (United States)

    2014-09-26

    Model for Nonlinear Oscillators of Duffing Type, Renato Spigler, SIAM J. Appl. Math. A Propagation of Chaos Result for Burgers’ Equation, A.S. Sznitman...Submitted. Nonlinear Parametric Oscillations in Certain Stochastic Systems: A Random van der Pol Oscillator , Renato Spigler, J. Stat. Phys. Submitted. A

  7. Cavity equations for a positive- or negative-refraction-index material with electric and magnetic nonlinearities

    Science.gov (United States)

    Mártin, Daniel A.; Hoyuelos, Miguel

    2009-11-01

    We study evolution equations for electric and magnetic field amplitudes in a ring cavity with plane mirrors. The cavity is filled with a positive or negative-refraction-index material with third-order effective electric and magnetic nonlinearities. Two coupled nonlinear equations for the electric and magnetic amplitudes are obtained. We prove that the description can be reduced to one Lugiato-Lefever equation with generalized coefficients. A stability analysis of the homogeneous solution, complemented with numerical integration, shows that any combination of the parameters should correspond to one of three characteristic behaviors.

  8. Creep characterization of gels and nonlinear viscoelastic material model

    Science.gov (United States)

    Ishikawa, Kiyotaka; Fujikawa, Masaki; Makabe, Chobin; Tanaka, Kou

    2016-07-01

    In this paper, we examine gel creep behavior and develop a material model for useful and simple numerical simulation of this behavior. This study has three stages and aims: (1) gel creep behavior is examined; (2) the material model is determined and the material constants are identified; and (3) the versatility of the material model and the constants are evaluated. The creep behavior is found to be independent of the initial stress level in the present experiment. Thus, the viscoelastic model proposed by Simo is selected, and its material constants are identified using the results of creep tests. Moreover, from the results of numerical calculations and experiments, it is found that the chosen material model has good reproducibility, predictive performance and high versatility.

  9. Decoupling Nonclassical Nonlinear Behavior of Elastic Wave Types

    Science.gov (United States)

    Remillieux, Marcel C.; Guyer, Robert A.; Payan, Cédric; Ulrich, T. J.

    2016-03-01

    In this Letter, the tensorial nature of the nonequilibrium dynamics in nonlinear mesoscopic elastic materials is evidenced via multimode resonance experiments. In these experiments the dynamic response, including the spatial variations of velocities and strains, is carefully monitored while the sample is vibrated in a purely longitudinal or a purely torsional mode. By analogy with the fact that such experiments can decouple the elements of the linear elastic tensor, we demonstrate that the parameters quantifying the nonequilibrium dynamics of the material differ substantially for a compressional wave and for a shear wave. This result could lead to further understanding of the nonlinear mechanical phenomena that arise in natural systems as well as to the design and engineering of nonlinear acoustic metamaterials.

  10. Enhanced nonlinear refractive index in epsilon-near-zero materials

    CERN Document Server

    Caspani, L; Clerici, M; Ferrera, M; Roger, T; Di Falco, A; Kim, J; Kinsey, N; Shalaev, V M; Boltasseva, A; Faccio, D

    2016-01-01

    New propagation regimes for light arise from the ability to tune the dielectric permittivity to extremely low values. Here we demonstrate a universal approach based on the low linear permittivity values attained in the epsilon-near-zero (ENZ) regime for enhancing the nonlinear refractive index, which enables remarkable light-induced changes of the material properties. Experiments performed on Al-doped ZnO (AZO) thin films show a six-fold increase of the Kerr nonlinear refractive index ($n_2$) at the ENZ wavelength, located in the 1300 nm region. This in turn leads to light-induced refractive index changes of the order of unity, thus representing a new paradigm for nonlinear optics.

  11. Local interaction simulation approach to modelling nonclassical, nonlinear elastic behavior in solids.

    Science.gov (United States)

    Scalerandi, Marco; Agostini, Valentina; Delsanto, Pier Paolo; Van Den Abeele, Koen; Johnson, Paul A

    2003-06-01

    Recent studies show that a broad category of materials share "nonclassical" nonlinear elastic behavior much different from "classical" (Landau-type) nonlinearity. Manifestations of "nonclassical" nonlinearity include stress-strain hysteresis and discrete memory in quasistatic experiments, and specific dependencies of the harmonic amplitudes with respect to the drive amplitude in dynamic wave experiments, which are remarkably different from those predicted by the classical theory. These materials have in common soft "bond" elements, where the elastic nonlinearity originates, contained in hard matter (e.g., a rock sample). The bond system normally comprises a small fraction of the total material volume, and can be localized (e.g., a crack in a solid) or distributed, as in a rock. In this paper a model is presented in which the soft elements are treated as hysteretic or reversible elastic units connected in a one-dimensional lattice to elastic elements (grains), which make up the hard matrix. Calculations are performed in the framework of the local interaction simulation approach (LISA). Experimental observations are well predicted by the model, which is now ready both for basic investigations about the physical origins of nonlinear elasticity and for applications to material damage diagnostics.

  12. A donor-nanotube paradigm for nonlinear optical materials.

    Science.gov (United States)

    Xiao, Dequan; Bulat, Felipe A; Yang, Weitao; Beratan, David N

    2008-09-01

    Studies of the nonlinear electronic response of donor/acceptor substituted nanotubes suggest a behavior that is both surprising and qualitatively distinct from that in conventional conjugated organic species. We find that the carbon nanotubes serve as both electronic bridges and acceptors, leading to a donor-nanotube paradigm for the effective design of large first hyperpolarizabilities. We also find that tuning the donor orientation, relative to the nanotube, can significantly enhance the first hyperpolarizability.

  13. Epileptic EEG: a comprehensive study of nonlinear behavior.

    Science.gov (United States)

    Daneshyari, Moayed; Kamkar, L Lily; Daneshyari, Matin

    2010-01-01

    In this study, the nonlinear properties of the electroencephalograph (EEG) signals are investigated by comparing two sets of EEG, one set for epileptic and another set for healthy brain activities. Adopting measures of nonlinear theory such as Lyapunov exponent, correlation dimension, Hurst exponent, fractal dimension, and Kolmogorov entropy, the chaotic behavior of these two sets is quantitatively computed. The statistics for the two groups of all measures demonstrate the differences between the normal healthy group and epileptic one. The statistical results along with phase-space diagram verify that brain under epileptic seizures possess limited trajectory in the state space than in healthy normal state, consequently behaves less chaotically compared to normal condition.

  14. Nonlinear electro-mechanobiological behavior of cell membrane during electroporation

    KAUST Repository

    Deng, Peigang

    2012-01-01

    A nonlinear electroporation (EP) model is proposed to study the electro-mechanobiological behavior of cell membrane during EP, by taking the nonlinear large deformation of the membrane into account. The proposed model predicts the critical transmembrane potential and the activation energy for EP, the equilibrium pore size, and the resealing process of the pore. Single-cell EP experiments using a micro EP chip were conducted on chicken red blood cells at different temperatures to determine the activation energy and the critical transmembrane potential for EP. The experimental results are in good agreement with the theoretical predictions. © 2012 American Institute of Physics.

  15. Electrodynamic soil plate oscillator: Modeling nonlinear mesoscopic elastic behavior and hysteresis in nonlinear acoustic landmine detection

    Science.gov (United States)

    Korman, M. S.; Duong, D. V.; Kalsbeck, A. E.

    2015-10-01

    significant curvature when the soil particle velocity is relatively higher. An oscillator with hysteresis modeled by a distribution of parallel spring elements each with a different threshold slip condition seems to describe fairly linear backbone curve behavior [W. D. Iwan, Transactions of the ASME, J. of Applied Mech., 33,(1966), 893-900], while a single bilinear hysteresis element describes the backbone curvature results in the experiments reported here [T. K. Caughey, Transactions of the ASME, J. of Applied Mech., 27, (1960), 640-643]. When "off target" resonances have a different backbone curvature than "on the mine" backbone curves, then false alarms may be eliminated due to resonances from the natural soil layering. See [R. A. Guyer, J. TenCate, and P. Johnson, "Hysteresis and the Dynamic Elasticity of Consolidated Granular Materials," Phys. Rev. Lett., 82, 16 (1999), 3280-3283] for recent models of nonlinear mesoscopic behavior.

  16. Nonlinearity-induced PT-symmetry without material gain

    Science.gov (United States)

    Miri, Mohammad-Ali; Alù, Andrea

    2016-06-01

    Parity-time symmetry has raised a great deal of attention in optics in recent years, yet its application has been so far hindered by the stringent requirements on coherent gain balanced with loss. In this paper, we show that the conditions to enable parity and time symmetry can be simultaneously satisfied for a pair of modes with mixed frequencies interacting in a nonlinear medium, without requiring the presence of material gain. First, we consider a guided wave structure with second order nonlinearity and we derive the PT-symmetric Hamiltonian that governs the interaction of two waves of mixed frequencies when accompanied by a high intensity pump beam at the sum frequency. We also extend the results to an array of coupled nonlinear waveguide channels. It is shown that the evolution dynamics of the low-frequency waves is associated with a periodic PT-symmetric lattice while the phase of the pump beams can be utilized as a control parameter to modify the gain and loss distribution, thus realizing different PT lattices by design. Our results suggest that nonlinear wave mixing processes can form a rich platform to realize PT-symmetric Hamiltonians of arbitrary dimensions in optical systems, without requiring material gain.

  17. Mathematical Systems Theory : from Behaviors to Nonlinear Control

    CERN Document Server

    Julius, A; Pasumarthy, Ramkrishna; Rapisarda, Paolo; Scherpen, Jacquelien

    2015-01-01

    This treatment of modern topics related to mathematical systems theory forms the proceedings of a workshop, Mathematical Systems Theory: From Behaviors to Nonlinear Control, held at the University of Groningen in July 2015. The workshop celebrated the work of Professors Arjan van der Schaft and Harry Trentelman, honouring their 60th Birthdays. The first volume of this two-volume work covers a variety of topics related to nonlinear and hybrid control systems. After giving a detailed account of the state of the art in the related topic, each chapter presents new results and discusses new directions. As such, this volume provides a broad picture of the theory of nonlinear and hybrid control systems for scientists and engineers with an interest in the interdisciplinary field of systems and control theory. The reader will benefit from the expert participants’ ideas on exciting new approaches to control and system theory and their predictions of future directions for the subject that were discussed at the worksho...

  18. Nonlinear vibration behaviors of casing pipe in the deep water

    Science.gov (United States)

    Tang, You-Gang; Zhang, Su-Xia; Yi, Cong

    2006-10-01

    The vortex-induced nonlinear vibration of casing pipes in the deep water was investigated considering the loads of current and combined wave-current. The vortex-induced vibration equation of a casing pipe was set up with considering the beam mode and Morison's nonlinear fluid loads as well as the vortex-excited loads. The approach of calculating vortex-excited nonlinear vibration by Galerkin's method was proposed. The natural vibration frequencies and modes were obtained, and the response including primary resonance induced by current and the composite resonance under combined wave-current for the 170 m long casing pipe in the 160 m depth of water were investigated. The results show that the dynamics response of casing pipe obviously increases, and the complicated response behaviors of casing pipe are described under combined wave-current.

  19. NONLINEAR BUCKLING CHARACTERISTIC OF GRADED MULTIWEB STRUCTURE OF HETEROGENEOUS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    LI Yong; ZHANG Zhi-min

    2005-01-01

    The graded multiweb structure of heterogeneous anisotropic materials, which makes full use of the continuous, gradual and changing physical mechanical performance of material properties, has a widespread application in aeroplane aerofoil structure and automobile lightweight structure. On the basis of laminate buckling theory,the equivalent rigidity method is adopted to establish the corresponding constitutive relation and the non-linear buckling governing equation for the graded multiweb structure. In finding the solution, the critical load of buckling under different complicated boundary conditions together with combined loads were obtained and testification of the experimental analysis shows that the calculation results can satisfy the requirements of engineering design in a satisfactory way. Results obtained from the research say that: graded materials can reduce the concentrated stress on the interface in an effective way and weaken the effect of initial defect in materials and thereby improve the strength and toughness of materials.

  20. Nonlinear Thermo-mechanical Finite Element Analysis of Polymer Foam Cored Sandwich Structures including Geometrical and Material Nonlinearity

    DEFF Research Database (Denmark)

    Palleti, Hara Naga Krishna Teja; Thomsen, Ole Thybo; Taher, Siavash Talebi;

    In this paper, polymer foam cored sandwich structures with fibre reinforced composite face sheets subjected to combined mechanical and thermal loads will be analysed using the commercial FE code ABAQUS® incorporating both material and geometrical nonlinearity. Large displacements and rotations ar...... are included in the analysis. The full nonlinear stress-strain curves up to failure will be considered for the polymer foams at different temperatures to study the effect of material nonlinearity in detail....

  1. Intrinsic optical bistability between left-handed material and nonlinear optical materials

    Institute of Scientific and Technical Information of China (English)

    Shi Hong-Yan; Jiang Yong-Yuan; Sun Xiu-Dong; Guo Ru-Hai; Zhao Yi-Ping

    2005-01-01

    The electromagnetic properties of the interface between a left-handed material and a conventional nonlinear material were investigated theoretically and numerically. We found a new phenomenon-optical bistability of the interface.It was shown that the incident intensity, incident angle and permeability ratio between the left-handed and the nonlinear materials could dramatically affect the optical bistable behaviour. We also compared the bistable behaviours of different electromagnetic modes. The results indicated that the TE mode was prior to the TM mode to obtain optical bistability for the same parameter.

  2. Frequency Response of Synthetic Vocal Fold Models with Linear and Nonlinear Material Properties

    Science.gov (United States)

    Shaw, Stephanie M.; Thomson, Scott L.; Dromey, Christopher; Smith, Simeon

    2012-01-01

    Purpose: The purpose of this study was to create synthetic vocal fold models with nonlinear stress-strain properties and to investigate the effect of linear versus nonlinear material properties on fundamental frequency (F[subscript 0]) during anterior-posterior stretching. Method: Three materially linear and 3 materially nonlinear models were…

  3. The thermomechanics of nonlinear irreversible behaviors an introduction

    CERN Document Server

    Maugin, Gérard A

    1999-01-01

    In this invaluable book, macroscopic irreversible thermodynamics is presented in its realm and its splendor by appealing to the notion of internal variables of state. This applies to both fluids and solids with or without microstructures of mechanical or electromagnetic origin. This unmatched richness of essentially nonlinear behaviors is the result of the use of modern mathematical techniques such as convex analysis in a clear-cut framework which allows one to put under the umbrella of "irreversible thermodynamics" behaviors which until now have been commonly considered either not easily cove

  4. Nonlinear Dynamic Behavior of Functionally Graded Truncated Conical Shell Under Complex Loads

    Science.gov (United States)

    Yang, S. W.; Hao, Y. X.; Zhang, W.; Li, S. B.

    Nonlinear dynamic behaviors of ceramic-metal graded truncated conical shell subjected to complex loads are investigated. The shell is modeled by first-order shear deformation theory. The nonlinear partial differential governing equation in terms of transverse displacements of the FGM truncated conical shell is derived from the Hamilton's principle. Galerkin's method is then utilized to discretize the partial governing equations to a two-degree-of-freedom nonlinear ordinary differential equation. The temperature-dependent materials properties of the constituents are graded in the radial direction in accordance with a power-law distribution. The aerodynamic pressure can be calculated by using the first-order piston theory. The temperature field is assumed to be a steady-state constant-temperature distribution. Bifurcation diagrams, the maximum Lyapunov exponents, wave forms and phase portraits are obtained by numerical simulation to demonstrate the complex nonlinear dynamics response of the FGM truncated conical shell. The influences of the semi-vertex angle, the material gradient index, in-plane and aerodynamic load on the nonlinear dynamics are studied.

  5. Nonlinear Optical Properties of a MMA-Silica Nanohybrid Material Doped with Rhodamine 6G

    Directory of Open Access Journals (Sweden)

    J. Lima-Gutiérrez

    2013-01-01

    Full Text Available A novel nanohybrid material based on MMA-Silica has been synthesized with an organic dye dopant (R6G to tailor the optical properties. This novel material can be used on several devices such as active laser media for an organic solid state laser, OLEDs, or as a characterization media for new organic dye molecules. Thin films were deposited by dip-coating and characterized by absorption and reflection UV-VIS, photoluminescence, SEM, and Z-scan technique to verify their nonlinear behavior. R6G dye dopant has been used to verify that the nanohybrid matrix does not inhibit its optical properties.

  6. On the Nonlinear Behavior of the Piezoelectric Coupling on Vibration-Based Energy Harvesters

    Directory of Open Access Journals (Sweden)

    Luciana L. Silva

    2015-01-01

    Full Text Available Vibration-based energy harvesting with piezoelectric elements has an increasing importance nowadays being related to numerous potential applications. A wide range of nonlinear effects is observed in energy harvesting devices and the analysis of the power generated suggests that they have considerable influence on the results. Linear constitutive models for piezoelectric materials can provide inconsistencies on the prediction of the power output of the energy harvester, mainly close to resonant conditions. This paper investigates the effect of the nonlinear behavior of the piezoelectric coupling. A one-degree of freedom mechanical system is coupled to an electrical circuit by a piezoelectric element and different coupling models are investigated. Experimental tests available in the literature are employed as a reference establishing the best matches of the models. Subsequently, numerical simulations are carried out showing different responses of the system indicating that nonlinear piezoelectric couplings can strongly modify the system dynamics.

  7. Computation of the effective nonlinear mechanical response of lattice materials considering geometrical nonlinearities

    Science.gov (United States)

    ElNady, Khaled; Goda, Ibrahim; Ganghoffer, Jean-François

    2016-09-01

    The asymptotic homogenization technique is presently developed in the framework of geometrical nonlinearities to derive the large strains effective elastic response of network materials viewed as repetitive beam networks. This works extends the small strains homogenization method developed with special emphasis on textile structures in Goda et al. (J Mech Phys Solids 61(12):2537-2565, 2013). A systematic methodology is established, allowing the prediction of the overall mechanical properties of these structures in the nonlinear regime, reflecting the influence of the geometrical and mechanical micro-parameters of the network structure on the overall response of the chosen equivalent continuum. Internal scale effects of the initially discrete structure are captured by the consideration of a micropolar effective continuum model. Applications to the large strain response of 3D hexagonal lattices and dry textiles exemplify the powerfulness of the proposed method. The effective mechanical responses obtained for different loadings are validated by FE simulations performed over a representative unit cell.

  8. Nonlinear phononics and structural control of strongly correlated materials

    Energy Technology Data Exchange (ETDEWEB)

    Mankowsky, Roman

    2016-01-20

    Mid-infrared light pulses can be used to resonantly excite infrared-active vibrational modes for the phase control of strongly correlated materials on subpicosecond timescales. As the energy is transferred directly into atomic motions, dissipation into the electronic system is reduced, allowing for the emergence of unusual low energy collective properties. Light-induced superconductivity, insulator-metal transitions and melting of magnetic order demonstrate the potential of this method. An understanding of the mechanism, by which these transitions are driven, is however missing. The aim of this work is to uncover this process by investigating the nonlinear lattice dynamics induced by the excitation and to elucidate their contribution to the modulation of collective properties of strongly correlated materials. The first signature of nonlinear lattice dynamics was reported in the observation of coherent phonon oscillations, resonant with the excitation of an infrared-active phonon mode in a manganite. This nonlinear phononic coupling can be described within a model, which predicts not only oscillatory coherent phonons dynamics but also directional atomic displacements along the coupled modes on average, which could cause the previously observed transitions. We verified this directional response and quantified the anharmonic coupling constant by tracing the atomic motions in a time-resolved hard X-ray diffraction experiment with sub-picometer spatial and femtosecond temporal resolution. In a subsequent study, we investigated the role of nonlinear lattice dynamics in the emergence of superconductivity far above the equilibrium transition temperature, an intriguing effect found to follow lattice excitation of YBa{sub 2}Cu{sub 3}O{sub 6+x}. By combining density functional theory (DFT) calculations of the anharmonic coupling constants with time-resolved X-ray diffraction experiments, we identified a structural rearrangement, which appears and decays with the same temporal

  9. Nonlinear dynamic behaviors of a floating structure in focused waves

    Science.gov (United States)

    Cao, Fei-feng; Zhao, Xi-zeng

    2015-12-01

    Floating structures are commonly seen in coastal and offshore engineering. They are often subjected to extreme waves and, therefore, their nonlinear dynamic behaviors are of great concern. In this paper, an in-house CFD code is developed to investigate the accurate prediction of nonlinear dynamic behaviors of a two-dimensional (2-D) box-shaped floating structure in focused waves. Computations are performed by an enhanced Constrained Interpolation Profile (CIP)-based Cartesian grid model, in which a more accurate VOF (Volume of Fluid) method, the THINC/SW scheme (THINC: tangent of hyperbola for interface capturing; SW: Slope Weighting), is used for interface capturing. A focusing wave theory is used for the focused wave generation. The wave component of constant steepness is chosen. Comparisons between predictions and physical measurements show good agreement including body motions and free surface profiles. Although the overall agreement is good, some discrepancies are observed for impact pressure on the superstructure due to water on deck. The effect of grid resolution on the results is checked. With a fine grid, no obvious improvement is seen in the global body motions and impact pressures due to water on deck. It is concluded that highly nonlinear phenomena, such as distorted free surface, large-amplitude body motions, and violent impact flow, have been predicted successfully.

  10. Mean-field theory of strongly nonlinear random composites: Strong power-law nonlinearity and scaling behavior

    Science.gov (United States)

    Wan, W. M. V.; Lee, H. C.; Hui, P. M.; Yu, K. W.

    1996-08-01

    The effective response of random media consisting of two different kinds of strongly nonlinear materials with strong power-law nonlinearity is studied. Each component satisfies current density and electric-field relation of the form J=χ\\|E\\|βE. A simple self-consistent mean-field theory, which leads to a simple way in determining the average local electric field in each constituent, is introduced. Each component is assumed to have a conductivity depending on the averaged local electric field. The averaged local electric field is then determined self-consistently. Numerical simulations of the system are carried out on random nonlinear resistor networks. Theoretical results are compared with simulation data, and excellent agreements are found. Results are also compared with the Hashin-Shtrikman lower bound proposed by Ponte Castaneda et al. [Phys. Rev. B 46, 4387 (1992)]. It is found that the present theory, at small contrasts of χ between the two components, gives a result identical to that of Ponte Castaneda et al. up to second order of the contrast. The crossover and scaling behavior of the effective response near the percolation threshold as suggested by the present theory are discussed and demonstrated.

  11. Nonlinear Optical Materials for the Smart Filtering of Optical Radiation.

    Science.gov (United States)

    Dini, Danilo; Calvete, Mário J F; Hanack, Michael

    2016-11-23

    The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the function of optical power limiting. All known mechanisms of optical limiting have been analyzed and discussed for the different types of materials.

  12. Nonlinear material behaviour of spider silk yields robust webs.

    Science.gov (United States)

    Cranford, Steven W; Tarakanova, Anna; Pugno, Nicola M; Buehler, Markus J

    2012-02-01

    Natural materials are renowned for exquisite designs that optimize function, as illustrated by the elasticity of blood vessels, the toughness of bone and the protection offered by nacre. Particularly intriguing are spider silks, with studies having explored properties ranging from their protein sequence to the geometry of a web. This material system, highly adapted to meet a spider's many needs, has superior mechanical properties. In spite of much research into the molecular design underpinning the outstanding performance of silk fibres, and into the mechanical characteristics of web-like structures, it remains unknown how the mechanical characteristics of spider silk contribute to the integrity and performance of a spider web. Here we report web deformation experiments and simulations that identify the nonlinear response of silk threads to stress--involving softening at a yield point and substantial stiffening at large strain until failure--as being crucial to localize load-induced deformation and resulting in mechanically robust spider webs. Control simulations confirmed that a nonlinear stress response results in superior resistance to structural defects in the web compared to linear elastic or elastic-plastic (softening) material behaviour. We also show that under distributed loads, such as those exerted by wind, the stiff behaviour of silk under small deformation, before the yield point, is essential in maintaining the web's structural integrity. The superior performance of silk in webs is therefore not due merely to its exceptional ultimate strength and strain, but arises from the nonlinear response of silk threads to strain and their geometrical arrangement in a web.

  13. Structure/property relationships in non-linear optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Cole, J.M. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)]|[Durham Univ. (United Kingdom); Howard, J.A.K. [Durham Univ. (United Kingdom); McIntyre, G.J. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    The application of neutrons to the study of structure/property relationships in organic non-linear optical materials (NLOs) is described. In particular, charge-transfer effects and intermolecular interactions are investigated. Charge-transfer effects are studied by charge-density analysis and an example of one such investigation is given. The study of intermolecular interactions concentrates on the effects of hydrogen-bonding and an example is given of two structurally similar molecules with very disparate NLO properties, as a result of different types of hydrogen-bonding. (author). 3 refs.

  14. Nonlinear behavior for nanoscale electrostatic actuators with Casimir force

    Energy Technology Data Exchange (ETDEWEB)

    Lin Wenhui [College of Science, China Agricultural University, Beijing 100083 (China); Zhao Yapu [State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080 (China)]. E-mail: yzhao@lnm.imech.ac.cn

    2005-03-01

    The influence of Casimir force on the nonlinear behavior of nanoscale electrostatic actuators is studied in this paper. A one degree of freedom mass-spring model is adopted and the bifurcation properties of the actuators are obtained. With the change of the geometrical dimensions, the number of equilibrium point varies from zero to two. Stability analysis shows that one equilibrium point is Hopf point and the other is unstable saddle point when there are two equilibrium points. We also obtain the phase portraits, in which the periodic orbits exist around the Hopf point, and a homoclinic orbit passes through the unstable saddle point.

  15. Nonlinear coda wave analysis of hysteretic elastic behavior in strongly scattering media

    Science.gov (United States)

    Ouarabi, M. Ait; Boubenider, F.; Gliozzi, A. S.; Scalerandi, M.

    2016-10-01

    Strongly scattering elastic media, such as consolidated granular materials, respond to ultrasonic pulse excitations with a long response signal with peculiar properties. The portion of the signal at late times, termed coda, is due to multiple scattering. It contains information about the elastic properties of the material, and it has been proven to be very sensitive to small variations in the modulus. Here we propose a technique based on a nonlinear analysis of the coda of a signal, which might be applied to quantify the nonlinear elastic response in consolidated granular media exhibiting a hysteretic elastic behavior. The method proposed allows for an intrinsic definition of the reference signal which is normally needed for applying coda-based methods.

  16. Thermal conductivities of some novel nonlinear optical materials.

    Science.gov (United States)

    Beasley, J D

    1994-02-20

    Results of thermal conductivity measurements are reported for several of the more recently developed nonlinear optical crystals. New or substantially revised values of thermal conductivity were obtained in six materials. Notable thermal conductivities measured were those for AgGaS(2) [0.014 W/(cm K) and 0.015 W/(cm K)], AgGaSe(2) [0.010 W/(cm K) and 0.011 W/(cm K)], beta barium borate [0.016 W/(cm K) and 0.012 W/(cm K)], and ZnGeP(2) [0.36 W/(cm K) and 0.35 W/(cm K)], with values quoted for directions respectively parallel and perpendicular to the optic axis for each material. These new data provide necessary input for the design of high-power optical frequency converters.

  17. Predicting Nonlinear Behavior and Stress-Strain Relationship of Rectangular Confined Reinforced Concrete Columns with ANSYS

    Directory of Open Access Journals (Sweden)

    A. Tata

    2009-01-01

    Full Text Available This paper presents a nonlinear finite element modeling and analysis of rectangular normal-strength reinforced concrete columns confined with transverse steel under axial compressive loading. In this study, the columns were modeled as discrete elements using ANSYS nonlinear finite element software. Concrete was modeled with 8-noded SOLID65 elements that can translate either in the x-, y-, or z-axis directions from ANSYS element library. Longitudinal and transverse steels were modeled as discrete elements using 3D-LINK8 bar elements available in the ANSYS element library. The nonlinear constitutive law of each material was also implemented in the model. The results indicate that the stress-strain relationships obtained from the analytical model using ANSYS are in good agreement with the experimental data. This has been confirmed with the insignificant difference between the analytical and experimental, i.e. 5.65 and 2.80 percent for the peak stress and the strain at the peak stress, respectively. The comparison shows that the ANSYS nonlinear finite element program is capable of modeling and predicting the actual nonlinear behavior of confined concrete column under axial loading. The actual stress-strain relationship, the strength gain and ductility improvement have also been confirmed to be satisfactorily.

  18. Nonlinear dynamic behaviors of ball bearing rotor system

    Institute of Scientific and Technical Information of China (English)

    WANG Li-qin; CUI Li; ZHENG De-zhi; GU Le

    2009-01-01

    Nonlinear forces and moments caused by ball bearing were calculated based on relationship of displacement and deflection and quasi-dynamic model of bearing. Five-DOF dynamic equations of rotor supported by ball bearings were estimated. The Newmark-β method and Newton-Laphson method were used to solve the equations. The dynamic characteristics of rotor system were studied through the time response, the phase portrait, the Poincar? maps and the bifurcation diagrams. The results show that the system goes through the quasiperiodic bifurcation route to chaos as rotate speed increases and there are several quasi-periodic regions and chaos regions. The amplitude decreases and the dynamic behaviors change as the axial load of ball bearing increases; the initial contact angle of ball bearing affects dynamic behaviors of the system obviously. The system can avoid non-periodic vibration by choosing structural parameters and operating parameters reasonably.

  19. Static compressive strength prediction of open-hole structure based on non-linear shear behavior and micro-mechanics

    Science.gov (United States)

    Li, Wangnan; Cai, Hongneng; Li, Chao

    2014-11-01

    This paper deals with the characterization of the strength of the constituents of carbon fiber reinforced plastic laminate (CFRP), and a prediction of the static compressive strength of open-hole structure of polymer composites. The approach combined with non-linear analysis in macro-level and a linear elastic micromechanical failure analysis in microlevel (non-linear MMF) is proposed to improve the prediction accuracy. A face-centered cubic micromechanics model is constructed to analyze the stresses in fiber and matrix in microlevel. Non-interactive failure criteria are proposed to characterize the strength of fiber and matrix. The non-linear shear behavior of the laminate is studied experimentally, and a novel approach of cubic spline interpolation is used to capture significant non-linear shear behavior of laminate. The user-defined material subroutine UMAT for the non-linear share behavior is developed and combined in the mechanics analysis in the macro-level using the Abaqus Python codes. The failure mechanism and static strength of open-hole compressive (OHC) structure of polymer composites is studied based on non-linear MMF. The UTS50/E51 CFRP is used to demonstrate the application of theory of non-linear MMF.

  20. Asymptotic behavior for a quadratic nonlinear Schrodinger equation

    Directory of Open Access Journals (Sweden)

    Pavel I. Naumkin

    2008-02-01

    Full Text Available We study the initial-value problem for the quadratic nonlinear Schrodinger equation $$displaylines{ iu_{t}+frac{1}{2}u_{xx}=partial _{x}overline{u}^{2},quad xin mathbb{R},; t>1, cr u(1,x=u_{1}(x,quad xin mathbb{R}. }$$ For small initial data $u_{1}in mathbf{H}^{2,2}$ we prove that there exists a unique global solution $uin mathbf{C}([1,infty ;mathbf{H}^{2,2}$ of this Cauchy problem. Moreover we show that the large time asymptotic behavior of the solution is defined in the region $|x|leq Csqrt{t}$ by the self-similar solution $frac{1}{sqrt{t}}MS(frac{x}{sqrt{t}}$ such that the total mass $$ frac{1}{sqrt{t}}int_{mathbb{R}}MS(frac{x}{sqrt{t}} dx=int_{mathbb{R}}u_{1}(xdx, $$ and in the far region $|x|>sqrt{t}$ the asymptotic behavior of solutions has rapidly oscillating structure similar to that of the cubic nonlinear Schrodinger equations.

  1. Crystal growth and characterizations of L-cystine dihydrobromide—A semiorganic nonlinear optical material

    Science.gov (United States)

    Anbuchezhiyan, M.; Ponnusamy, S.; Muthamizhchelvan, C.

    2010-02-01

    Single crystal of a new semiorganic nonlinear optical material, L-cystine dihydrobromide, was grown successfully from aqueous solution by slow evaporation method. The grown crystals were characterized by single crystal X-ray diffraction technique to determine the cell parameters. Powder X-ray diffraction analysis also confirms the structure of the grown title compound. The functional groups and vibrational frequencies have been identified using FTIR and FT Raman spectral data. Transmittance of the title compound was analyzed using UV-Vis spectrum. The mechanical strength of the grown crystal was found using Vickers microhardness measurement. The thermal stability of the grown crystal was determined with the aid of thermogravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Second order nonlinear optical behavior of the grown crystal has been confirmed by Kurtz powder second harmonic generation (SHG) test and its SHG efficiency was found as deff=0.38 deff (KDP).

  2. Crystal growth and characterizations of L-cystine dihydrobromide-A semiorganic nonlinear optical material

    Energy Technology Data Exchange (ETDEWEB)

    Anbuchezhiyan, M. [Department of Physics, Valliammai Engineering College, S.R.M. Nagar, Kattankulathur 603 203, Chennai (India); Ponnusamy, S., E-mail: suruponnus@gmail.co [Centre for Material Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603 203, Chennai (India); Muthamizhchelvan, C. [Centre for Material Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603 203, Chennai (India)

    2010-02-15

    Single crystal of a new semiorganic nonlinear optical material, L-cystine dihydrobromide, was grown successfully from aqueous solution by slow evaporation method. The grown crystals were characterized by single crystal X-ray diffraction technique to determine the cell parameters. Powder X-ray diffraction analysis also confirms the structure of the grown title compound. The functional groups and vibrational frequencies have been identified using FTIR and FT Raman spectral data. Transmittance of the title compound was analyzed using UV-Vis spectrum. The mechanical strength of the grown crystal was found using Vickers microhardness measurement. The thermal stability of the grown crystal was determined with the aid of thermogravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Second order nonlinear optical behavior of the grown crystal has been confirmed by Kurtz powder second harmonic generation (SHG) test and its SHG efficiency was found as d{sub eff}=0.38d{sub eff} (KDP).

  3. The Effect of Temperature Dependent Material Nonlinearities on the Response of Piezoelectric Composite Plates

    Science.gov (United States)

    Lee, Ho-Jun; Saravanos, Dimitris A.

    1997-01-01

    Previously developed analytical formulations for piezoelectric composite plates are extended to account for the nonlinear effects of temperature on material properties. The temperature dependence of the composite and piezoelectric properties are represented at the material level through the thermopiezoelectric constitutive equations. In addition to capturing thermal effects from temperature dependent material properties, this formulation also accounts for thermal effects arising from: (1) coefficient of thermal expansion mismatch between the various composite and piezoelectric plies and (2) pyroelectric effects on the piezoelectric material. The constitutive equations are incorporated into a layerwise laminate theory to provide a unified representation of the coupled mechanical, electrical, and thermal behavior of smart structures. Corresponding finite element equations are derived and implemented for a bilinear plate element with the inherent capability to model both the active and sensory response of piezoelectric composite laminates. Numerical studies are conducted on a simply supported composite plate with attached piezoceramic patches under thermal gradients to investigate the nonlinear effects of material property temperature dependence on the displacements, sensory voltages, active voltages required to minimize thermal deflections, and the resultant stress states.

  4. A stabilized complementarity formulation for nonlinear analysis of 3D bimodular materials

    Science.gov (United States)

    Zhang, L.; Zhang, H. W.; Wu, J.; Yan, B.

    2016-06-01

    Bi-modulus materials with different mechanical responses in tension and compression are often found in civil, composite, and biological engineering. Numerical analysis of bimodular materials is strongly nonlinear and convergence is usually a problem for traditional iterative schemes. This paper aims to develop a stabilized computational method for nonlinear analysis of 3D bimodular materials. Based on the parametric variational principle, a unified constitutive equation of 3D bimodular materials is proposed, which allows the eight principal stress states to be indicated by three parametric variables introduced in the principal stress directions. The original problem is transformed into a standard linear complementarity problem (LCP) by the parametric virtual work principle and a quadratic programming algorithm is developed by solving the LCP with the classic Lemke's algorithm. Update of elasticity and stiffness matrices is avoided and, thus, the proposed algorithm shows an excellent convergence behavior compared with traditional iterative schemes. Numerical examples show that the proposed method is valid and can accurately analyze mechanical responses of 3D bimodular materials. Also, stability of the algorithm is greatly improved.

  5. Basic Studies of Nonlinear Optical Materials for Eye and Sensor Protection

    Science.gov (United States)

    2004-03-10

    1 BASIC STUDIES OF NONLINEAR OPTICAL MATERIALS FOR EYE AND SENSOR PROTECTION I. Abstract: We have studied the spectroscopy, kinetics and...study liquid or solid materials from CW to 100x10-15 seconds. Basic Studies of Nonlinear Optical Materials for Eye and Sensor Protection

  6. Complex spatiotemporal behavior in a chain of one-way nonlinearly coupled elements

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Berkemer, Rainer; Gorria, C.;

    2011-01-01

    The dynamics of asymmetrically coupled nonlinear elements is considered. It is shown that there are two distinctive regimes of oscillatory behavior of one-way nonlinearly coupled elements depending on the relaxation time and the strength of the coupling. In the subcritical regime when...... nonlinear model....

  7. Linear and nonlinear behavior of human and artificial lip reeds

    Science.gov (United States)

    Campbell, Murray; Richards, Orlando

    2003-10-01

    In a musical instrument of the lip reed aerophone class, the flow of air from the player's lungs into the resonating air column is modulated by the periodic opening and closing of the pressure-controlled valve formed by the player's lips. The nature of the operation of this valve has been the subject of considerable study in recent years. Since the pressure-flow relationship is strongly nonlinear, the behavior of the coupled system of lips and air column can only be modeled using the methods of nonlinear dynamics. Extensive studies of artificial lip reeds, in which the lips are simulated by water-filled latex tubes, have shown them to be capable of reproducing musically important features of human playing, including the lipping of notes both below and above an acoustic resonance of the air column. Measurements of the linear response of artificial reeds have guided the development of more realistic models of the lip reed, while studies of both real and artificial lips using a high-speed digital camera have shed fresh light on the nature of the lip motion at the large amplitudes typical of loud playing. [Work supported by EPSRC.

  8. Membrane behavior of clay liner materials

    Science.gov (United States)

    Kang, Jong Beom

    Membrane behavior represents the ability of porous media to restrict the migration of solutes, leading to the existence of chemico-osmosis, or the flow of liquid in response to a chemical concentration gradient. Membrane behavior is an important consideration with respect to clay soils with small pores and interactive electric diffuse double layers associated with individual particles, such as bentonite. The results of recent studies indicate the existence of membrane behavior in bentonite-based hydraulic barriers used in waste containment applications. Thus, measurement of the existence and magnitude of membrane behavior in such clay soils is becoming increasingly important. Accordingly, this research focused on evaluating the existence and magnitude of membrane behavior for three clay-based materials that typically are considered for use as liners for waste containment applications, such as landfills. The three clay-based liner materials included a commercially available geosynthetic clay liner (GCL) consisting of sodium bentonite sandwiched between two geotextiles, a compacted natural clay known locally as Nelson Farm Clay, and compacted NFC amended with 5% (dry wt.) of a sodium bentonite. The study also included the development and evaluation of a new flexible-wall cell for clay membrane testing that was used subsequently to measure the membrane behaviors of the three clay liner materials. The consolidation behavior of the GCL under isotropic states of stress also was evaluated as a preliminary step in the determination of the membrane behavior of the GCL under different effective consolidation stresses.

  9. Nonlinear behavior of vibrating molecules on suspended graphene waveguides

    CERN Document Server

    Banerjee, Amrita

    2015-01-01

    Suspended graphene waveguides were deposited on micron-scale periodic metal (plasmonic) structures. Raman scattering of test molecules (B. Megaterium), deposited on the waveguides' surface, exhibited azimuthal cycles upon rotation: at these micron scales, spontaneous Raman ought to be independent of phase matching conditions. In addition, we observed angular-selective quadratic intensity dependence contrary to the typical linear behavior of spontaneous Raman. The effects were observed at very modest pump laser intensities (<10 MW/cm2 at the sample surface, oftenly used in Raman experiments). We attributed these observations to nonlinear coupling between the vibrating molecules and surface plasmon polariton (SPP) modes at the molecular vibration frequency. It was assessed that the polariton mode propagates through fairly long distances (over 100 microns).

  10. Dynamic behavior of a nonlinear rational difference equation and generalization

    Directory of Open Access Journals (Sweden)

    Shi Qihong

    2011-01-01

    Full Text Available Abstract This paper is concerned about the dynamic behavior for the following high order nonlinear difference equation x n = (x n-k + x n-m + x n-l /(x n-k x n-m + x n-m x n-l +1 with the initial data { x - l , x - l + 1 , … , x - 1 } ∈ ℝ + l and 1 ≤ k ≤ m ≤ l. The convergence of solution to this equation is investigated by introducing a new sequence, which extends and includes corresponding results obtained in the references (Li in J Math Anal Appl 312:103-111, 2005; Berenhaut et al. Appl. Math. Lett. 20:54-58, 2007; Papaschinopoulos and Schinas J Math Anal Appl 294:614-620, 2004 to a large extent. In addition, some propositions for generalized equations are reported.

  11. Influence of spiral framework on nonlinear optical materials.

    Science.gov (United States)

    Hu, Yang-Yang; Sun, Shi-Ling; Tian, Wen-Tao; Tian, Wei Quan; Xu, Hong-Liang; Su, Zhong-Min

    2014-04-04

    A series of spiral donor-π-acceptor frameworks (i.e. 2-2, 3-3, 4-4, and 5-5) based on 4-nitrophenyldiphenylamine with π-conjugated linear acenes (naphthalenes, anthracenes, tetracenes, and pentacenes) serving as the electron donor and nitro (NO2 ) groups serving as the electron acceptor were designed to investigate the relationships between the nonlinear optical (NLO) responses and the spirality in the frameworks. A parameter denoted as D was defined to describe the extent of the spiral framework. The D value reached its maximum if the number of NO2 groups was equal to the number of fused benzene rings contained in the linear acene. A longer 4-nitrophenyldiphenylamine chain led to a larger D value and, further, to a larger first hyperpolarizability. Different from traditional NLO materials with charge transfer occurring in the one-dimensional direction, charge transfer in 2-2, 3-3, 4-4, and 5-5 occur in three-dimensional directions due to the attractive spiral frameworks, and this is of great importance in the design of NLO materials. The origin of such an enhancement in the NLO properties of these spiral frameworks was explained with the aid of molecular orbital analysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Research on testing the nonlinear optical performance of nonlinear optical materials based on the effect of second-harmonic generation.

    Science.gov (United States)

    Li, Bing-Xuan; Wei, Yong; Huang, Cheng-Hui; Zhuang, Feng-Jiang; Zhang, Ge; Guo, Guo-Cong

    2014-01-01

    In the present paper the authors report a research on testing the nonlinear optical performance of optical materials in visible and infrared band. Based on the second order nonlinear optic principle and the photoelectric signal detection technology, the authors have proposed a new testing scheme in which a infrared OPO laser and a method for separating the beams arising from frequency matching and the light produced by other optical effects were used. The OPO laser is adopted as light source to avoid the error of measurement caused by absorption because the double frequency signal of the material is in the transmittance band Our research work includes testing system composition, operational principle and experimental method. The experimental results of KTP, KDP, AGS tested by this method were presented. In the experiment several new infrared non-linear materials were found. This method possesses the merits of good stability and reliability, high sensitivity, simple operation and good reproducibility, which can effectively make qualitative and semi-quantitative test for optical material's nonlinear optical properties from visible to infrared. This work provides an important test -method for the research on second order nonlinear optical materials in visible, infrared and ultraviolet bands.

  13. Nonlinear wave mixing and susceptibility properties of negative refractive index materials.

    Science.gov (United States)

    Chowdhury, Aref; Tataronis, John A

    2007-01-01

    We present an analysis of second-order and third-order nonlinear susceptibilities and wave-mixing properties of negative refractive index materials. We show that the nonlinear susceptibilities for noncentrosymmetric and centrosymmetric media may be positive or negative and away from resonance depending on the frequency of interest relative to the resonant frequencies of the material. Manipulation of the signs of the nonlinear susceptibilities is important in the field of optics, particularly for solitons and compensation of nonlinear effects. We also show that three- and four-wave mixing can be naturally phase matched in the material.

  14. Graphene Oxides as Tunable Broadband Nonlinear Optical Materials for Femtosecond Laser Pulses.

    Science.gov (United States)

    Jiang, Xiao-Fang; Polavarapu, Lakshminarayana; Neo, Shu Ting; Venkatesan, T; Xu, Qing-Hua

    2012-03-15

    Graphene oxide (GO) thin films on glass and plastic substrates were found to display interesting broadband nonlinear optical properties. We have investigated their optical limiting activity for femtosecond laser pulses at 800 and 400 nm, which could be tuned by controlling the extent of reduction. The as-prepared GO films were found to exhibit excellent broadband optical limiting behaviors, which were significantly enhanced upon partial reduction by using laser irradiation or chemical reduction methods. The laser-induced reduction of GO resulted in enhancement of effective two-photon absorption coefficient at 400 nm by up to ∼19 times and enhancement of effective two- and three-photon absorption coefficients at 800 nm by ∼12 and ∼14.5 times, respectively. The optical limiting thresholds of partially reduced GO films are much lower than those of various previously reported materials. Highly reduced GO films prepared by using the chemical method displayed strong saturable absorption behavior.

  15. Asymptotic behavior of solutions to nonlinear parabolic equation with nonlinear boundary conditions

    Directory of Open Access Journals (Sweden)

    Diabate Nabongo

    2008-01-01

    Full Text Available We show that solutions of a nonlinear parabolic equation of second order with nonlinear boundary conditions approach zero as t approaches infinity. Also, under additional assumptions, the solutions behave as a function determined here.

  16. An isogeometric Reissner-Mindlin shell element for dynamic analysis considering geometric and material nonlinearities

    Science.gov (United States)

    Sobota, Paul; Dornisch, Wolfgang; Klinkel, Sven

    2016-08-01

    The present approach deals with the dynamical analysis of thin structures using an isogeometric Reissner-Mindlin shell formulation. Here, a consistent and a lumped mass matrix are employed for the implicit time integration method. The formulation allows for large displacements and finite rotations. The Rodrigues formula, which incorporates the axial vector is used for the rotational description. It necessitates an interpolation of the director vector in the current configuration. Two concept for the interpolation of the director vector are presented. They are denoted as continuous interpolation method and discrete interpolation method. The shell formulation is based on the assumption of zero stress in thickness direction. In the present formulation an interface to 3D nonlinear material laws is used. It leads to an iterative procedure at each integration point. Here, a J2 plasticity material law is implemented. The suitability of the developed shell formulation for natural frequency analysis is demonstrated in numerical examples. Transient problems undergoing large deformations in combination with nonlinear material behavior are analyzed. The effectiveness, robustness and superior accuracy of the two interpolation methods of the shell director vector are investigated and are compared to numerical reference solutions.

  17. Cavity equations for a positive or negative refraction index material with electric and magnetic non-linearities

    CERN Document Server

    Mártin, Daniel A; 10.1103/PhysRevE.80.056601

    2012-01-01

    We study evolution equations for electric and magnetic field amplitudes in a ring cavity with plane mirrors. The cavity is filled with a positive or negative refraction index material with third order effective electric and magnetic non-linearities. Two coupled non-linear equations for the electric and magnetic amplitudes are obtained. We prove that the description can be reduced to one Lugiato Lefever equation with generalized coefficients. A stability analysis of the homogeneous solution, complemented with numerical integration, shows that any combination of the parameters should correspond to one of three characteristic behaviors.

  18. Inclusion Tuning of Nonlinear Optical Materials: KTP (Potassium Titanyl Phosphate) Isomorphs

    Science.gov (United States)

    1988-06-01

    o OFCE OF NAVAL RESEARCH Contract N00014-87-K-0457 V R&T Code 4134015-01 0) Technical. Report No. 23 "Inclusion Tuning of Nonlinear Optical Materials : KIP...bry block nuum.ber) see attached #11 Inclusion Tuning of Nonlinear Optical Materials : KTP Isomorphs * Q1 UISTRISUTION/AVAII..ASILITY 00 ABSTRACT 21

  19. Eye/Sensor Protection against Laser Irradiation Organic Nonlinear Optical Materials

    Science.gov (United States)

    1989-06-12

    Recent developments in organic nonlinear optical materials for application to eye and sensor protection are reviewed. This compendium includes a...noteworthy organic third-order nonlinear optical materials is included as an appendix. Lasers are playing an important and increasing role in modern

  20. The Synthesis of Third—order Optical Nonlinear Organic Polyheterocyclic Materials

    Institute of Scientific and Technical Information of China (English)

    JianRongGAO; LuBaiCHENG; 等

    2002-01-01

    Synthesis of the third-order nonlinear materials:bis (1,4-dihydroxynaphthalene) tetrathiafulvalene and bis (1,4-dialkoxylnaphthalene) tetrathiafulvalene has been achieved in four steps, starting from 2,3-dichloro-1,4-naphthaquinone. The materials exhibit larger third-order nonlinear optical susceptibilities χ.

  1. Growth and characterization of an organic nonlinear optical material: L-Histidine malonate

    Science.gov (United States)

    Ramya, K.; Saraswathi, N. T.; Raja, C. Ramachandra

    2016-10-01

    L-Histidine malonate is one of the potential organic material for nonlinear optical applications. Single crystals of L-Histidine malonate were grown by the liquid diffusion method. The lattice parameter values were evaluated from single crystal X-ray diffraction technique. The Fourier Transform Infra Red and Raman spectral studies were employed to identify the different modes of vibrations of molecular groups in the crystal. Optical characterization and the percentage of optical transmission were recorded using UV-vis-NIR spectroscopy. The molecular structure was established by proton and carbon Nuclear magnetic resonance spectral studies. The thermal behavior of the material has been studied by Thermo gravimetric and Differential thermal plots. The second harmonic generation conversion efficiency was found out from the powder technique of Kurtz and Perry.

  2. L-Cystine hydrochloride: A novel semi-organic nonlinear optical material for optical devices

    Science.gov (United States)

    Selvaraju, K.; Valluvan, R.; Kirubavathi, K.; Kumararaman, S.

    2007-01-01

    A new semi-organic nonlinear optical (NLO) material L-cystine hydrochloride (LCHCl) was grown in large size measuring 19 × 5 × 3 mm 3 by slow solvent evaporation technique for the first time in literature. The cell parameter values were determined by single crystal X-ray diffraction studies. Fourier Transform Infrared spectroscopic analysis was carried out on the grown sample to ascertain the fundamental functional groups. Thermal behavior of the grown LCHCl sample was analyzed by TG & DTA analysis. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. The optical transmission studies and second harmonic generation (SHG) efficiency studies justified the device quality of the grown crystal and the SHG study reveals that the grown sample has nearly 1.2 times higher efficiency than that of potassium dihydrogen phosphate (KDP), a well known NLO material.

  3. The Behavior of Filters and Smoothers for Strongly Nonlinear Dynamics

    Science.gov (United States)

    Zhu, Yanqiu; Cohn, Stephen E.; Todling, Ricardo

    1999-01-01

    The Kalman filter is the optimal filter in the presence of known Gaussian error statistics and linear dynamics. Filter extension to nonlinear dynamics is non trivial in the sense of appropriately representing high order moments of the statistics. Monte Carlo, ensemble-based, methods have been advocated as the methodology for representing high order moments without any questionable closure assumptions (e.g., Miller 1994). Investigation along these lines has been conducted for highly idealized dynamics such as the strongly nonlinear Lorenz (1963) model as well as more realistic models of the oceans (Evensen and van Leeuwen 1996) and atmosphere (Houtekamer and Mitchell 1998). A few relevant issues in this context are related to the necessary number of ensemble members to properly represent the error statistics and, the necessary modifications in the usual filter equations to allow for correct update of the ensemble members (Burgers 1998). The ensemble technique has also been applied to the problem of smoothing for which similar questions apply. Ensemble smoother examples, however, seem to quite puzzling in that results of state estimate are worse than for their filter analogue (Evensen 1997). In this study, we use concepts in probability theory to revisit the ensemble methodology for filtering and smoothing in data assimilation. We use Lorenz (1963) model to test and compare the behavior of a variety implementations of ensemble filters. We also implement ensemble smoothers that are able to perform better than their filter counterparts. A discussion of feasibility of these techniques to large data assimilation problems will be given at the time of the conference.

  4. Computational Modeling of Ultrafast Pulse Propagation in Nonlinear Optical Materials

    Science.gov (United States)

    Goorjian, Peter M.; Agrawal, Govind P.; Kwak, Dochan (Technical Monitor)

    1996-01-01

    There is an emerging technology of photonic (or optoelectronic) integrated circuits (PICs or OEICs). In PICs, optical and electronic components are grown together on the same chip. rib build such devices and subsystems, one needs to model the entire chip. Accurate computer modeling of electromagnetic wave propagation in semiconductors is necessary for the successful development of PICs. More specifically, these computer codes would enable the modeling of such devices, including their subsystems, such as semiconductor lasers and semiconductor amplifiers in which there is femtosecond pulse propagation. Here, the computer simulations are made by solving the full vector, nonlinear, Maxwell's equations, coupled with the semiconductor Bloch equations, without any approximations. The carrier is retained in the description of the optical pulse, (i.e. the envelope approximation is not made in the Maxwell's equations), and the rotating wave approximation is not made in the Bloch equations. These coupled equations are solved to simulate the propagation of femtosecond optical pulses in semiconductor materials. The simulations describe the dynamics of the optical pulses, as well as the interband and intraband.

  5. Thermally Stable Heterocyclic Imines as New Potential Nonlinear Optical Materials

    Science.gov (United States)

    Nesterov, Volodymyr V.; Antipin, Mikhail Y.; Nesterov, Vladimir N.; Moore, Craig E.; Cardelino, Beatriz H.; Timofeeva, Tatiana V.

    2004-01-01

    In the course of a search for new thermostable acentric nonlinear optical crystalline materials, several heterocyclic imine derivatives were designed, with the general structure D-pi-A(D'). Introduction of a donor amino group (D') into the acceptor moiety was expected to bring H-bonds into their crystal structures, and so to elevate their melting points and assist in an acentric molecular packing. Six heterocycle-containing compounds of this type were prepared, single crystals were grown for five of them, and these crystals were characterized by X-ray analysis. A significant melting temperature elevation was found for all of the synthesized compounds. Three of the compounds were also found to crystallize in acentric space groups. One of the acentric compounds is built as a three-dimensional H-bonded molecular network. In the other two compounds, with very similar molecular structure, the molecules form one-dimensional H-bonded head-to-head associates (chains). These chains are parallel in two different crystallographic directions and form very unusual interpenetrating chain patterns in an acentric crystal. Two of the compounds crystallized with centrosymmetric molecular packing.

  6. Analysis of nonlinear optical properties in donor–acceptor materials

    Energy Technology Data Exchange (ETDEWEB)

    Day, Paul N. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); General Dynamics Information Technology, Inc., Dayton, Ohio 45431 (United States); Pachter, Ruth [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); Nguyen, Kiet A. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); UES, Inc., Dayton, Ohio 45432 (United States)

    2014-05-14

    Time-dependent density functional theory has been used to calculate nonlinear optical (NLO) properties, including the first and second hyperpolarizabilities as well as the two-photon absorption cross-section, for the donor-acceptor molecules p-nitroaniline and dimethylamino nitrostilbene, and for respective materials attached to a gold dimer. The CAMB3LYP, B3LYP, PBE0, and PBE exchange-correlation functionals all had fair but variable performance when compared to higher-level theory and to experiment. The CAMB3LYP functional had the best performance on these compounds of the functionals tested. However, our comprehensive analysis has shown that quantitative prediction of hyperpolarizabilities is still a challenge, hampered by inadequate functionals, basis sets, and solvation models, requiring further experimental characterization. Attachment of the Au{sub 2}S group to molecules already known for their relatively large NLO properties was found to further enhance the response. While our calculations show a modest enhancement for the first hyperpolarizability, the enhancement of the second hyperpolarizability is predicted to be more than an order of magnitude.

  7. RANDOM MICROSTRUCTURE FINITE ELEMENT METHOD FOR EFFECTIVE NONLINEAR PROPERTIES OF COMPOSITE MATERIALS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Some theoretical methods have been reported to deal with nonlinear problems of composite materials but the accuracy is not so good. In the meantime, a lot of nonlinear problems are difficult to be managed by the theoretical methods. The present study aims to use the developed method, the random microstructure finite element method, to deal with these nonlinear problems. In this paper, the random microstructure finite element method is used to deal with all three kinds of nonlinear property problems of composite materials. The analyzed results suggest that the influences of the nonlinear phenomena on the effective properties of composite materials are significant and the random microstructure finite element method is an efficient tool to investigate the nonlinear problems.

  8. Nonlocal description of X waves in quadratic nonlinear materials

    DEFF Research Database (Denmark)

    Larsen, Peter Ulrik Vingaard; Sørensen, Mads Peter; Bang, Ole

    2006-01-01

    We study localized light bullets and X-waves in quadratic media and show how the notion of nonlocality can provide an alternative simple physical picture of both types of multi-dimensional nonlinear waves. For X-waves we show that a local cascading limit in terms of a nonlinear Schrodinger equation...

  9. Measurement and fitting techniques for the assessment of material nonlinearity using nonlinear Rayleigh waves

    Energy Technology Data Exchange (ETDEWEB)

    Torello, David [GW Woodruff School of Mechanical Engineering, Georgia Tech (United States); Kim, Jin-Yeon [School of Civil and Environmental Engineering, Georgia Tech (United States); Qu, Jianmin [Department of Civil and Environmental Engineering, Northwestern University (United States); Jacobs, Laurence J. [School of Civil and Environmental Engineering, Georgia Tech and GW Woodruff School of Mechanical Engineering, Georgia Tech (United States)

    2015-03-31

    This research considers the effects of diffraction, attenuation, and the nonlinearity of generating sources on measurements of nonlinear ultrasonic Rayleigh wave propagation. A new theoretical framework for correcting measurements made with air-coupled and contact piezoelectric receivers for the aforementioned effects is provided based on analytical models and experimental considerations. A method for extracting the nonlinearity parameter β{sub 11} is proposed based on a nonlinear least squares curve-fitting algorithm that is tailored for Rayleigh wave measurements. Quantitative experiments are conducted to confirm the predictions for the nonlinearity of the piezoelectric source and to demonstrate the effectiveness of the curve-fitting procedure. These experiments are conducted on aluminum 2024 and 7075 specimens and a β{sub 11}{sup 7075}/β{sub 11}{sup 2024} measure of 1.363 agrees well with previous literature and earlier work.

  10. Optimization of hardening/softening behavior of plane frame structures using nonlinear normal modes

    DEFF Research Database (Denmark)

    Dou, Suguang; Jensen, Jakob Søndergaard

    2016-01-01

    /softening behavior of nonlinear mechanical systems. The iterative optimization procedure consists of calculation of nonlinear normal modes, solving an adjoint equation system for sensitivity analysis and an update of design variables using a mathematical programming tool. We demonstrate the method with examples......Devices that exploit essential nonlinear behavior such as hardening/softening and inter-modal coupling effects are increasingly used in engineering and fundamental studies. Based on nonlinear normal modes, we present a gradient-based structural optimization method for tailoring the hardening...

  11. Hysteretic behavior modeling of elastoplastic materials

    Directory of Open Access Journals (Sweden)

    Šumarac Dragoslav

    2008-01-01

    Full Text Available In the present paper the Preisach model of hysteresis is applied to model cyclic behavior of elasto-plastic material. Rate of loading and viscous effects will not be considered. The problem of axial loading of rectangular cross section and cyclic bending of rectangular tube (box will be studied in details. Hysteretic stress-strain loop for prescribed history of stress change is plotted for material modeled by series connection of three unite element. Also moment-curvature hysteretic loop is obtained for a prescribed curvature change of rectangular tube (box. One chapter of the paper is devoted to results obtained by FEM using Finite Element Code ABAQUS. All obtained results clearly show advantages of the Preisach model for describing cyclic behavior of elasto-plastic material.

  12. Nonlinear Behavior Of Saturated Porous Media Under External Impact

    Science.gov (United States)

    Perepechko, Y.

    2005-12-01

    This paper deals with nonlinear behavior of liquid saturated porous media in gravity filed under external impact. The continuum is assumed to be a two-velocity medium; it consists of a deformable porous matrix (with Maxwell's reology) and a Newtonian liquid that saturates this matrix. The energy dissipation in this model takes place due the interface friction between the solid matrix and saturating liquid, and also through relaxation of inelastic shear stress in the porous matrix. The elaborated nonisothermal mathematical model for this kind of medium is a thermodynamically consistent and closed model. Godunov's explicit difference scheme was used for computer simulation; the method implies numerical simulation for discontinuity decay in flux calculations. As an illustrative example, we consider the formation of dissipation structures in a plain layer of that medium after pulse or periodic impact on the background of liquid filtration through the porous matrix. At the process beginning, one can observe elastic behavior of the porous matrix. Deformation spreading through the saturated porous matrix occurs almost without distortions and produces a channel-shaped zone of stretching with a high porosity. Later on, dissipation processes and reology properties of porous medium causes the diffusion of this channel. We also observe a correlation between the liquid distribution (porosity for the solid matrix) and dilatancy fields; this allows us to restore the dilatancy field from the measured fluid saturation of the medium. This work was supported by the RFBR (Grant No. 04-05-64107), the Presidium of SB RAS (Grant 106), the President's Grants (NSh-2118.2003.5, NSh-1573.2003.5).

  13. Dynamic acousto-elastic test using continuous probe wave and transient vibration to investigate material nonlinearity.

    Science.gov (United States)

    Eiras, J N; Vu, Q A; Lott, M; Payá, J; Garnier, V; Payan, C

    2016-07-01

    This study demonstrates the feasibility of the dynamic acousto-elastic effect of a continuous high frequency wave for investigating the material nonlinearity upon transient vibration. The approach is demonstrated on a concrete sample measuring 15×15×60cm(3). Two ultrasonic transducers (emitter and receiver) are placed at its middle span. A continuous high frequency wave of 500kHz propagates through the material and is modulated with a hammer blow. The position of the hammer blow on the sample is configured to promote the first bending mode of vibration. The use of a continuous wave allows discrete time extraction of the nonlinear behavior by a short-time Fourier transform approach, through the simultaneous comparison of a reference non-modulated signal and an impact-modulated signal. The hammer blow results in phase shifts and variations of signal amplitude between reference and perturbed signals, which are driven by the resonant frequency of the sample. Finally, a comprehensive analysis of the relaxation mechanisms (modulus and attenuation recovery) is conducted to untangle the coupled fast and slow hysteretic effects. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. High-accuracy acoustic detection of nonclassical component of material nonlinearity.

    Science.gov (United States)

    Haupert, Sylvain; Renaud, Guillaume; Rivière, Jacques; Talmant, Maryline; Johnson, Paul A; Laugier, Pascal

    2011-11-01

    The aim is to assess the nonclassical component of material nonlinearity in several classes of materials with weak, intermediate, and high nonlinear properties. In this contribution, an optimized nonlinear resonant ultrasound spectroscopy (NRUS) measuring and data processing protocol applied to small samples is described. The protocol is used to overcome the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic nonlinearity. External temperature fluctuation is identified as a primary source of measurement contamination. For instance, a variation of 0.1 °C produced a frequency variation of 0.01%, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to overcome environmental effects, the reference frequency measurements are repeated before each excitation level and then used to compute nonlinear parameters. Using this approach, relative resonant frequency shifts of 10(-5) can be measured, which is below the limit of 10(-4) often considered as the limit of NRUS sensitivity under common experimental conditions. Due to enhanced sensitivity resulting from the correction procedure applied in this work, nonclassical nonlinearity in materials that before have been assumed to only be classically nonlinear in past work (steel, brass, and aluminum) is reported.

  15. Finding the Next Deep-Ultraviolet Nonlinear Optical Material: NH4B4O6F.

    Science.gov (United States)

    Shi, Guoqiang; Wang, Ying; Zhang, Fangfang; Zhang, Bingbing; Yang, Zhihua; Hou, Xueling; Pan, Shilie; Poeppelmeier, Kenneth R

    2017-08-09

    Nonlinear optical materials are essential for the development of solid-state lasers. KBe2BO3F2 (KBBF) is a unique nonlinear optical material for generation of deep-ultraviolet coherent light; however, its industrial application is limited. Here, we report a new material NH4B4O6F, which exhibits a wide deep-ultraviolet transparent range and suitable birefringence that enables frequency doubling below 200 nm. NH4B4O6F possesses large nonlinear coefficients about 2.5 times that of KBBF. In addition, it is easy to grow bulk crystals and does not contain toxic elements.

  16. Augmented twin-nonlinear two-box behavioral models for multicarrier LTE power amplifiers.

    Science.gov (United States)

    Hammi, Oualid

    2014-01-01

    A novel class of behavioral models is proposed for LTE-driven Doherty power amplifiers with strong memory effects. The proposed models, labeled augmented twin-nonlinear two-box models, are built by cascading a highly nonlinear memoryless function with a mildly nonlinear memory polynomial with cross terms. Experimental validation on gallium nitride based Doherty power amplifiers illustrates the accuracy enhancement and complexity reduction achieved by the proposed models. When strong memory effects are observed, the augmented twin-nonlinear two-box models can improve the normalized mean square error by up to 3 dB for the same number of coefficients when compared to state-of-the-art twin-nonlinear two-box models. Furthermore, the augmented twin-nonlinear two-box models lead to the same performance as previously reported twin-nonlinear two-box models while requiring up to 80% less coefficients.

  17. Augmented Twin-Nonlinear Two-Box Behavioral Models for Multicarrier LTE Power Amplifiers

    Directory of Open Access Journals (Sweden)

    Oualid Hammi

    2014-01-01

    Full Text Available A novel class of behavioral models is proposed for LTE-driven Doherty power amplifiers with strong memory effects. The proposed models, labeled augmented twin-nonlinear two-box models, are built by cascading a highly nonlinear memoryless function with a mildly nonlinear memory polynomial with cross terms. Experimental validation on gallium nitride based Doherty power amplifiers illustrates the accuracy enhancement and complexity reduction achieved by the proposed models. When strong memory effects are observed, the augmented twin-nonlinear two-box models can improve the normalized mean square error by up to 3 dB for the same number of coefficients when compared to state-of-the-art twin-nonlinear two-box models. Furthermore, the augmented twin-nonlinear two-box models lead to the same performance as previously reported twin-nonlinear two-box models while requiring up to 80% less coefficients.

  18. Nonlinear behavior of three-terminal graphene junctions at room temperature

    Science.gov (United States)

    Kim, Wonjae; Pasanen, Pirjo; Riikonen, Juha; Lipsanen, Harri

    2012-03-01

    We demonstrate nonlinear behavior in three-terminal T-branch graphene devices at room temperature. A rectified nonlinear output at the center branch is observed when the device is biased by a push-pull configuration. Nonlinearity is assumed to arise from a difference in charge transfer through the metal-graphene contact barrier between two contacts. The sign of the rectification can be altered by changing the carrier type using the back-gate voltage.

  19. Investigation of nonlinear optical properties of various organic materials by the Z-scan method

    Science.gov (United States)

    Ganeev, R. A.; Boltaev, G. S.; Tugushev, R. I.; Usmanov, T.

    2012-06-01

    We have studied the nonlinear optical properties of various organic materials (vegetable oil, juice, wine, cognac, Coca-Cola and Fanta drinks, Nescafé coffee, tea, gasoline, clock oil, glycerol, and polyphenyl ether) that are used in everyday life. Their nonlinearities have been studied by the Z-scan method in the near-IR and visible spectral ranges. We have shown that the majority of samples possess a nonlinear absorption; however, some of the studied materials show a strong saturated absorption and nonlinear refraction. Red wine and glycerol proved to be the most interesting materials. For these samples, we have observed a change in the sign of the nonlinear absorption with increasing laser intensity, which was attributed to the competition between two-photon absorption and saturated absorption.

  20. A review of recent theoretical studies in nonlinear crystals: towards the design of new materials

    Science.gov (United States)

    Luppi, Eleonora; Véniard, Valérie

    2016-12-01

    Nonlinear optics is an important and exciting field of fundamental and applied research, with applications in many different disciplines such as physics chemistry, material science and biology. In the recent years, nonlinear optical phenomena started to be also widely used in technological applications for optoelectronics and photovoltaics. This coincided with an important experimental and theoretical search for new materials with an efficient and exploitable nonlinear optical response. Here, starting from the discovery of nonlinear optics, we review the most important theoretical formalisms developed to understand, interpret and predict the nonlinear optical phenomena. We show the different level of approximation of the many-electrons interactions that these formalisms can describe which are fundamental in the interpretation of the experiments. The impact of the theory is then analyzed on different classes of new materials particularly studied in these years: silicon bulk to nano, compound semiconductors, graphene, transition metal dichalcogenide, hexagonal boron nitride and borate crystals.

  1. Modeling the macroscopic behavior of two-phase nonlinear composites by infinite-rank laminates

    Science.gov (United States)

    Idiart, Martín I.

    A new approach is proposed for estimating the macroscopic behavior of two-phase nonlinear composites with random, particulate microstructures. The central idea is to model composites by sequentially laminated constructions of infinite rank whose macroscopic behavior can be determined exactly. The resulting estimates incorporate microstructural information up to the two-point correlation functions, and require the solution to a Hamilton-Jacobi equation with the inclusion concentration and the macroscopic fields playing the role of 'time' and 'spatial' variables, respectively. Because they are realizable, by construction, these estimates are guaranteed to be convex, to satisfy all pertinent bounds, to exhibit no duality gap, and to be exact to second order in the heterogeneity contrast. Sample results are provided for two- and three-dimensional power-law composites, and are compared with other homogenization estimates, as well as with numerical simulations available from the literature. The estimates are found to give physically sensible predictions for all the cases considered, even for extreme values of the nonlinearity and heterogeneity contrast. Interestingly, in the case of isotropic porous materials under hydrostatic loadings, the estimates agree exactly with standard Gurson-type models for viscoplastic porous media.

  2. The Synthesis of Third-order Optical Nonlinear Organic Polyheterocyclic Materials

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Synthesis of the third-order nonlinear materials: bis (l,4-dihydroxynaphthalene)tetrathiafulvalene and bis (1,4-dialkoxylnaphthalene) tetrathiafulvalene has been achieved in four steps, starting from 2,3-dichloro-l,4-naphthaquinone. The matcrials exhibit larger third-order nonlinear optical susceptibilities X(3).

  3. Exact solutions of optical pulse propagation in nonlinear meta-materials

    Science.gov (United States)

    Nanda, Lipsa

    2017-01-01

    An analytical and simulation based method has been used to exactly solve the nonlinear wave propagation in bulk media exhibiting frequency dependent dielectric susceptibility and magnetic permeability. The method has been further extended to investigate the intensity distribution in a nonlinear meta-material with negative refractive index where both ɛ and μ are dispersive and negative in nature.

  4. Analysis of Dynamic Model of a Structure with Nonlinear Damped Behavior

    Directory of Open Access Journals (Sweden)

    G. Domairry

    2010-04-01

    Full Text Available In this work, it has been attempted to analytically treat the nonlinear behavior of structures. Since analysing nonlinear problems is of great difficulty, different numerical methods and software are advised to treat such problems. Despite the increasing expenses of building structures to maintain their linear behavior, nonlinearity has been inevitable, and therefore, nonlinear analysis has beenof great importance to the scientists in the field. As structures confront lateral forces and intense earthquakes especially near fault regions, a part of the structure remains linear, but some part of itbehaves nonlinearly for example dampers, columns and beams. This is simulated by a damped in nonlinear oscillator. In this paper, the nonlinear equation of oscillator with damping which has nonlinear behavior is representative of the dynamic behavior of a structure has been solved analytically. In the end, the obtained results are compared with numerical ones and shown in graphs and in tables;analytical solutions are in good agreement with those of the numerical method.

  5. Measurements and Modeling of the Nonlinear Behavior of a Guitar Pickup at Low Frequencies †

    Directory of Open Access Journals (Sweden)

    Antonin Novak

    2017-01-01

    Full Text Available Description of the physical behavior of electric guitars is still not very widespread in the scientific literature. In particular, the physical models describing a nonlinear behavior of pickups still requires some refinements. The study presented in this paper is focused on nonlinear modeling of the pickups. Two main issues are raised. First, is the currently most used nonlinear model (a Hammerstein model sufficient for the complex nonlinear behavior of the pickup? In other words, would a more complex model, such as a Generalized Hammerstein that can deal better with the nonlinear memory, yield better results? The second troublesome issue is how to measure the nonlinear behavior of a pickup correctly. A specific experimental set-up allowing for driving the pickup in a controlled way (string displacement perpendicular to the pickup and to separate the nonlinear model of the pickup from other nonlinearities in the measurement chain is proposed. Thanks to this experimental set-up, a Generalized Hammerstein model of the pickup is estimated for frequency range 15–500 Hz and the results are compared with a simple Hammerstein model. A comparison with experimental results shows that both models succeed in describing the pickup when used in realistic conditions.

  6. Probing material nonlinearity at various depths by time reversal mirrors

    Science.gov (United States)

    Payan, C.; Ulrich, T. J.; Le Bas, P. Y.; Griffa, M.; Schuetz, P.; Remillieux, M. C.; Saleh, T. A.

    2014-04-01

    In this Letter, the time reversal mirror is used to focus elastic energy at a prescribed location and to analyze the amplitude dependence of the focus signal, thus providing the nonlinearity of the medium. By varying the frequency content of the focused waveforms, the technique can be used to probe the surface, by penetrating to a depth defined by the wavelength of the focused waves. The validity of this concept is shown in the presence of gradual and distributed damage in concrete by comparing actual results with a reference nonlinear measurement and X ray tomography images.

  7. Probing material nonlinearity at various depths by time reversal mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Payan, C. [LMA UPR CNRS 7051, Aix Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille (France); Ulrich, T. J.; Le Bas, P. Y.; Remillieux, M. C. [Los Alamos National Laboratory, EES-17, Los Alamos, New Mexico 87545 (United States); Griffa, M.; Schuetz, P. [Swiss Federal Laboratories for Materials Science and Technology (EMPA), Überlandstrasse 129, 8600 Dübendorf (Switzerland); Saleh, T. A. [Los Alamos National Laboratory, MST-16, Los Alamos, New Mexico 87545 (United States)

    2014-04-07

    In this Letter, the time reversal mirror is used to focus elastic energy at a prescribed location and to analyze the amplitude dependence of the focus signal, thus providing the nonlinearity of the medium. By varying the frequency content of the focused waveforms, the technique can be used to probe the surface, by penetrating to a depth defined by the wavelength of the focused waves. The validity of this concept is shown in the presence of gradual and distributed damage in concrete by comparing actual results with a reference nonlinear measurement and X ray tomography images.

  8. A Multiscale, Nonlinear, Modeling Framework Enabling the Design and Analysis of Composite Materials and Structures

    Science.gov (United States)

    Bednarcyk, Brett A.; Arnold, Steven M.

    2012-01-01

    A framework for the multiscale design and analysis of composite materials and structures is presented. The ImMAC software suite, developed at NASA Glenn Research Center, embeds efficient, nonlinear micromechanics capabilities within higher scale structural analysis methods such as finite element analysis. The result is an integrated, multiscale tool that relates global loading to the constituent scale, captures nonlinearities at this scale, and homogenizes local nonlinearities to predict their effects at the structural scale. Example applications of the multiscale framework are presented for the stochastic progressive failure of a SiC/Ti composite tensile specimen and the effects of microstructural variations on the nonlinear response of woven polymer matrix composites.

  9. Geometrically nonlinear deformation and the emergent behavior of polarons in soft matter.

    Science.gov (United States)

    Li, Xiaobao; Liu, Liping; Sharma, Pradeep

    2015-11-07

    Mechanical strain can alter the electronic structure of both bulk semiconductors as well as nanostructures such as quantum dots. This fact has been extensively researched and exploited for tailoring electronic properties. The strain mediated interaction between the charge carriers and the lattice is interpreted through the so-called deformation potential. In the case of soft materials or nanostructures, such as DNA, the deformation potential leads to the formation of polarons which largely determine the electronic characteristics of DNA and similar polymer entities. In addition, polarons are also speculated to be responsible for the mechanism of quantum actuation in carbon nanotubes. The deformation potential is usually taken to be a linear function of the lattice deformation (U ∼ αε) where α is the deformation potential "constant" that determines the coupling strength and ε is the mechanical strain. In this letter, by carefully accounting for nonlinear geometric deformation that has been hitherto ignored so far in this context, we show that the deformation potential constant is renormalized in a non-trivial manner and is hardly a constant. It varies spatially within the material and with the size of the material. This effect, while negligible for hard materials, is found to be important for soft materials and critically impacts the interpretation of quantities such as polaron size, binding energy, and accordingly, electronic behavior.

  10. Self-Assembly of Nanocomposite Nonlinear Optical Materials for Photonic Devices Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This program targets the development of new highly anisotropic nonlinear optical nanocomposite materials for NASA and non-NASA applications in advanced photonic and...

  11. Spatial localization of nonlinear waves spreading in materials in the presence of dislocations and point defects

    Science.gov (United States)

    Erofeev, V. I.; Leontieva, A. V.; Malkhanov, A. O.

    2017-06-01

    Within the framework of self consistent dynamic problems, the impact of dislocations and point defects on the spatial localization of nonlinear acoustic waves propagating in materials has been studied.

  12. Spontaneous emission and nonlinear effects in photonic bandgap materials

    Science.gov (United States)

    Fogel, Ishella S.; Bendickson, Jon M.; Tocci, Michael D.; Bloemer, Mark J.; Scalora, Michael; Bowden, Charles M.; Dowling, Jonathan P.

    1998-03-01

    We summarize and review our theoretical and experimental work on spontaneous emission and nonlinear effects in one-dimensional, photonic bandgap (PBG) structures. We present a new result: a method for calculating the normal-mode solutions - and hence the spontaneous emission of embedded emitters - in an arbitrary, linear, lossless, one-dimensional, PBG structure.

  13. Asymptotic behavior of a nonlinear functional-integral equation of cell kinetics with unequal division.

    Science.gov (United States)

    Arino, O; Kimmel, M

    1989-01-01

    A model of cell cycle kinetics is proposed, which includes unequal division of cells, and a nonlinear dependence of the fraction of cells re-entering proliferation on the total number of cells in the cycle. The model is described by a nonlinear functional-integral equation. It is analyzed using the operator semigroup theory combined with classical differential equations approach. A complete description of the asymptotic behavior of the model is provided for a relatively broad class of nonlinearities. The nonnegative solutions either tend to a stable steady state, or to zero. The simplicity of the model makes it an interesting step in the analysis of dynamics of nonlinear structure populations.

  14. Non-Linear Optical Studies of IR Materials with Infrared Femtosecond Laser

    Science.gov (United States)

    2016-12-15

    AFRL-RD-PS- AFRL-RD-PS- TR-2016-0055 TR-2016-0055 NON-LINEAR OPTICAL STUDIES OF IR MATERIALS WITH INFRARED FEMTOSECOND LASER Enam...ANDREAS SCHMITT-SODY, DR-III ERIN PETTYJOHN, DR-III Program Manager Deputy Chief, High Power Electromagnetics Division This...TITLE AND SUBTITLE Non-Linear Optical Studies of IR Materials with Infrared Femtosecond Laser 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9451-14-1

  15. Hybrid Nonlinear Optical Materials for Applications in Power Limiting and Photorefractive Devices

    Science.gov (United States)

    2010-03-01

    Final 3. DATES COVERED (From - To) 04/01/2007 to 11/30/2009 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER FA9550-07-1-0307 Hybrid Nonlinear Optical Materials for...Hybrid  Nonlinear   Optical   Materials  for Applications in Power  Limiting and Photorefractive devices      Prime Contract: FA95500710307

  16. Microcrack Identification in Cement-Based Materials Using Nonlinear Acoustic Waves

    Science.gov (United States)

    Chen, X. J.; Kim, J.-Y.; Qu, J.; Kurtis, K. E.; Wu, S. C.; Jacobs, L. J.

    2007-03-01

    This paper presents results from tests that use nonlinear acoustic waves to distinguish microcracks in cement-based materials. Portland cement mortar samples prepared with alkali-reactive aggregate were exposed to an aggressive environment to induce cracking were compared to control samples, of the same composition, but which were not exposed to aggressive conditions. Two nonlinear ultrasonic methods were used to characterize the samples, with the aim of identifying the time and extent of microcracking; these techniques were a nonlinear acoustical modulation (NAM) method and a harmonic amplitude relation (HAR) method. These nonlinear acoustic results show that both methods can distinguish damaged samples from undamaged ones, demonstrating the potential of nonlinear acoustic waves to provide a quantitative evaluation of the deterioration of cement-based materials.

  17. Numerical Investigation for the Microstructural Effects on the Crack Growth Behavior of Particulate Composite Materials

    Science.gov (United States)

    2006-07-26

    When the damage constitutive law is adopted in an analysis, we perform an incremental analysis, just like the case of elastoplasticity (see Okada...isotropic elastoplasticity . 2.4 Some other issues associated with the damage constitutive law-initiation of nonlinear deformation Material...ABSTRACT In present investigation, analyses for the damage evolution behavior of particulate composite materials by using the finite element method

  18. Simulación numérica del comportamiento no-lineal de materiales utilizando el método sin malla de puntos finitos Meshless numerical simulation of the non-linear behavior of a material using the finite point method

    Directory of Open Access Journals (Sweden)

    Luis Pérez P

    2011-12-01

    Full Text Available La formulación sin malla del método de puntos finitos permite aprovechar en toda su potencialidad la ventaja de este tipo de técnica numérica, habiéndose comprobado su buen funcionamiento para aplicaciones en los campos de la mecánica de fluidos, mecánica de sólidos, ciencia de materiales y más tarde en adaptividad y electromagnetismo. En el presente trabajo se desarrolla una metodología numérica para aproximar el comportamiento no-lineal de un material mediante el método de puntos finitos, basada en la teoría de deformación total de Hencky, en conjunto con un enfoque elástico para aproximar la distribución de tensiones y de deformaciones. Esta aproximación introduce el concepto de propiedades efectivas del material, las cuales se obtienen en forma iterativa mediante un procedimiento de corrección aplicado sobre la curva experimental de tensión-deformación. Los ejemplos desarrollados demuestran el correcto comportamiento de la metodología utilizada, siendo una de sus principales ventajas la sencillez y facilidad de su implementación, puesto que no es necesaria la partición o subdivisión del dominio de solución.The use of fully meshless formulation of the finite point method allows taking advantage the benefit of this type of numerical technique for applications in the fields of fluid mechanics, solid mechanics, material science and later in adaptivity and electromagnetism. In this work a meshless numerical method to approximate the non-linear behavior of a material using the finite point method, based on the theory of Hencky total strain and elastic approach to approximate the distribution of stresses and deformation, is developed. This approach introduces the concept of effective properties of the material which are obtained using a correction procedure applied to the stress-strain curve. The examples show the good behavior of the methodology that is used, being one of the main advantages the simplicity and the ease of

  19. Electrets in soft materials: nonlinearity, size effects, and giant electromechanical coupling.

    Science.gov (United States)

    Deng, Qian; Liu, Liping; Sharma, Pradeep

    2014-07-01

    Development of soft electromechanical materials is critical for several tantalizing applications such as soft robots and stretchable electronics, among others. Soft nonpiezoelectric materials can be coaxed to behave like piezoelectrics by merely embedding charges and dipoles in their interior and assuring some elastic heterogeneity. Such so-called electret materials have been experimentally shown to exhibit very large electromechanical coupling. In this work, we derive rigorous nonlinear expressions that relate effective electromechanical coupling to the creation of electret materials. In contrast to the existing models, we are able to both qualitatively and quantitatively capture the known experimental results on the nonlinear response of electret materials. Furthermore, we show that the presence of another form of electromechanical coupling, flexoelectricity, leads to size effects that dramatically alter the electromechanical response at submicron feature sizes. One of our key conclusions is that nonlinear deformation (prevalent in soft materials) significantly enhances the flexoelectric response and hence the aforementioned size effects.

  20. Homogeneous solutions for elliptically polarized light in a cavity containing materials with electric and magnetic nonlinearities

    CERN Document Server

    Martin, D A

    2015-01-01

    We study evolution equations and stationary homogeneous solutions for electric and magnetic field amplitudes in a ring cavity with flat mirrors. The cavity is filled with a positive or negative refraction index material with third order Kerr-like electric nonlinearities and also magnetic nonlinearities, which can be relevant in metamaterials. We consider the degree of freedom of polarization in the incident beam. It is found that considering a magnetic nonlinearity increases the variety of possible qualitatively different solutions. A classification of solutions is proposed in terms of the number of bifurcations. The analysis can be useful for the implementation of optical switching or memory storage using ring cavities with non linear materials.

  1. Multiaxial mechanical behavior of biological materials.

    Science.gov (United States)

    Sacks, Michael S; Sun, Wei

    2003-01-01

    For native and engineered biological tissues, there exist many physiological, surgical, and medical device applications where multiaxial material characterization and modeling is required. Because biological tissues and many biocompatible elastomers are incompressible, planar biaxial testing allows for a two-dimensional (2-D) stress-state that can be used to fully characterize their three-dimensional (3-D) mechanical properties. Biological tissues exhibit complex mechanical behaviors not easily accounted for in classic elastomeric constitutive models. Accounting for these behaviors by careful experimental evaluation and formulation of constitutive models continues to be a challenging area in biomechanical modeling and simulation. The focus of this review is to describe the application of multiaxial testing techniques to soft tissues and their relation to modern biomechanical constitutive theories.

  2. On the nonlinear axisymmetric dynamic buckling behavior of clamped functionally graded spherical caps

    Science.gov (United States)

    Prakash, T.; Sundararajan, N.; Ganapathi, M.

    2007-01-01

    Here, the dynamic thermal buckling behavior of functionally graded spherical caps is studied considering geometric nonlinearity based on von Karman's assumptions. The formulation is based on first-order shear deformation theory and it includes the in-plane and rotary inertia effects. The material properties are graded in the thickness direction according to the power-law distribution in terms of volume fractions of the material constituents. The effective material properties are evaluated using homogenization method. The governing equations obtained using finite element approach are solved employing the Newmark's integration technique coupled with a modified Newton-Raphson iteration scheme. The pressure load corresponding to a sudden jump in the maximum average displacement in the time history of the shell structure is taken as the dynamic buckling load. The present model is validated against the available isotropic case. A detailed numerical study is carried out to highlight the influences of shell geometries, power law index of functional graded material and boundary conditions on the dynamic buckling load of shallow spherical shells.

  3. Nonlinear Magnetic Phenomena in Highly Polarized Target Materials

    CERN Document Server

    Kiselev, Yu F

    2007-01-01

    The report introduces and surveys nonlinear magnetic phenomena which have been observed at high nuclear polarizations in polarized targets of the SMC and of the COMPASS collaborations at CERN. Some of these phenomena, namely the frequency modulation eect and the distortion of the NMR line shape, promote the development of the polarized target technique. Others, as the spin-spin cross-relaxation between spin subsystems can be used for the development of quantum statistical physics. New findings bear on an electromagnetic noise and the spectrally resolved radiation from LiD with negatively polarized nuclei detected by low temperature bolometers. These nonlinear phenomena need to be taken into account for achieving the ultimate polarizations.

  4. Nonlinear behavior analysis of spur gear pairs with a one-way clutch

    Science.gov (United States)

    Gill-Jeong, Cheon

    2007-04-01

    Nonlinear behavior analysis of a paired spur gear system with a one-way clutch was used to verify whether a one-way clutch is effective for reducing torsional vibration. The dynamic responses were studied over a wide frequency range by speed sweeping to check the nonlinear behavior using numerical integration. The gear system with a one-way clutch showed typical nonlinear behavior, such as softening nonlinearity and jump phenomena. The oscillating component of the dynamic transmission error was reduced over the entire frequency range compared to a system without a one-way clutch, and double-side contact could be prevented, even with very small backlash. Installing a one-way clutch on both sides of the gear system was more effective at mitigating the negative effects of various parameter changes than installing one only on the input or output side.

  5. An analysis of nonlinear behavior in delta-sigma modulators

    Science.gov (United States)

    Ardalan, Sasan H.; Paulos, John J.

    1987-06-01

    The paper introduces a new method of analysis for delta-sigma modulators based on modeling the nonlinear quantizer with a linearized gain, obtained by minimizing a mean-square-error criterion, followed by an additive noise source representing distortion components. In the paper, input signal amplitude dependencies of delta-sigma modulator stability and signal-to-noise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signal-to-noise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable third-order delta-sigma modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomena are explained by the nonlinear analysis of this paper. The analysis is carried out for both dc and sinusoidal excitations.

  6. Effects of stress and physical ageing on nonlinear creep behavior of poly(methyl methacrylate)

    Institute of Scientific and Technical Information of China (English)

    赵荣国; 陈朝中; 李其抚; 罗文波

    2008-01-01

    The effects of stress,ageing time and ageing temperature on creep behavior of poly(methyl methacrylate) were studied.After annealing above its glass transition temperature for a period of time to eliminate the stress and thermal history,the specimens were quenched and aged at various ageing temperatures for different ageing time,and then the short-term creep tests under different stress levels were carried out at room temperature.The creep strains were modeled by means of time-ageing time equivalence and time-stress equivalence,and the master creep curves were constructed via ageing time shift factors and stress shift factors.The results indicate that the creep rate increases with stress,while decreases with ageing time,and the ageing temperature history obviously affects the creep rate.For linear viscoelastic material,the ageing shift rate is independent on imposed stress,while for nonlinear viscoelastic material,the ageing shift rate decreases with increasing stress.The unified master creep curve up to 540 d at reference state was constructed by shifting the creep curves horizontally along the logarithmic time axis to overlap each other.It is demonstrated that the time-stress equivalence,united with the time-ageing time equivalence,provides an effective accelerated characterization technique in the laboratory to evaluate the long-term creep behavior of physical ageing polymers.

  7. Frequency Response of Synthetic Vocal Fold Models with Linear and Nonlinear Material Properties

    Science.gov (United States)

    Shaw, Stephanie M.; Thomson, Scott L.; Dromey, Christopher; Smith, Simeon

    2014-01-01

    Purpose The purpose of this study was to create synthetic vocal fold models with nonlinear stress-strain properties and to investigate the effect of linear versus nonlinear material properties on fundamental frequency during anterior-posterior stretching. Method Three materially linear and three materially nonlinear models were created and stretched up to 10 mm in 1 mm increments. Phonation onset pressure (Pon) and fundamental frequency (F0) at Pon were recorded for each length. Measurements were repeated as the models were relaxed in 1 mm increments back to their resting lengths, and tensile tests were conducted to determine the stress-strain responses of linear versus nonlinear models. Results Nonlinear models demonstrated a more substantial frequency response than did linear models and a more predictable pattern of F0 increase with respect to increasing length (although range was inconsistent across models). Pon generally increased with increasing vocal fold length for nonlinear models, whereas for linear models, Pon decreased with increasing length. Conclusions Nonlinear synthetic models appear to more accurately represent the human vocal folds than linear models, especially with respect to F0 response. PMID:22271874

  8. Music from chaos: nonlinear dynamical systems as generators of musical materials

    OpenAIRE

    Bidlack, Rick Aaron

    1990-01-01

    A body of scientific/mathematical theory arising from a description of the behavior of complex dynamical systems is explored in terms of its pertinence to and utility in musical schemes for the generation of melodic lines and textures. Such systems are known to model significant behavioral features of real-world phenomena, including turbulent or chaotic behavior. Many of the features of nonlinear dynamical systems that are intriguing from a mathematical point of view, especially the propertie...

  9. Exposing the nonlinear viscoelastic behavior of asphalt-aggregate mixes

    Science.gov (United States)

    Levenberg, Eyal; Uzan, Jacob

    2012-05-01

    In this study asphalt-aggregate mixes are treated as both viscoelastic and viscoplastic. Following a damage mechanics approach, a nonlinear viscoelastic constitutive formulation is generated from a linear formulation by replacing `applied stresses' with `effective viscoelastic stresses'. A non-dimensional scalar entity called `relative viscoelastic stiffness' is introduced; it is defined as the ratio of applied to effective viscoelastic stress and encapsulates different types of nonlinearities. The paper proposes a computational scheme for exposing these nonlinearities by uncovering, through direct analysis of any test data, changes experienced by the `relative viscoelastic stiffness'. In general terms, the method is based on simultaneous application of creep and relaxation formulations while preserving the interrelationship between the corresponding time functions. The proposed scheme is demonstrated by analyzing a uniaxial tension test and a uniaxial compression test (separately). Results are presented and discussed, unveiling and contrasting the character of viscoelastic nonlinearities in both cases. A conceptual viewpoint is offered to explain the observations, illustrating the requirements from any candidate constitutive theory.

  10. Molecular design of porphyrin-based nonlinear optical materials.

    Science.gov (United States)

    Keinan, Shahar; Therien, Michael J; Beratan, David N; Yang, Weitao

    2008-11-27

    Nonlinear optical chromophores containing (porphyrinato)Zn(II), proquinoid, and (terpyridyl)metal(II) building blocks were optimized in a library containing approximately 10(6) structures using the linear combination of atomic potentials (LCAP) methodology. We report here the library design and molecular property optimizations. Two basic structural types of large beta(0) chromophores were examined: linear and T-shaped motifs. These T-shaped geometries suggest a promising NLO chromophoric architecture for experimental investigation and further support the value of performing LCAP searches in large chemical spaces.

  11. Associating Specific Materials with Topological Insulation Behavior

    Science.gov (United States)

    Zhang, Xiuwen

    2014-03-01

    The first-principles (a) total-energy/stability calculations combined with (b) electronic structure calculations of band inversion, spin-polarization and topological invariants (Z2) has led to the design and prediction of specific materials that are topological insulators in this study. We classify bulk materials into four types of band-inversion behaviors (TI-1, TI-2, BI-3, BI-4), based on the number of band inversions and their distributions on various time reversal invariant k points. Depending on the inversion type in bulk, the corresponding surface states have different protections e.g., protected by time reversal symmetry (in TI-1 materials), spatial symmetry (in TI-2), or not protected (in BI-3, BI-4). Subject 1 Discovery of new TI by screening materials for a Z2 metric: Such high-throughput search in the framework of Inverse Design methodology predicts a few previously undocumented materials that are TI-1 in their ground state crystal structure. We also predict dozens of materials that are TI-1 however in structures that are not ground states (e.g. perovskite structure of II-Bi-O3). Subject 2 Design Principle to increase the gap of TI-1 materials: In HgTe-like cubic topological materials, the insulating gap is zero since the spin-orbit splitting is positive and so a 4-fold half-filled p-like band is near the Fermi level. By design of hybridization of d-orbitals into the p-like bands, one can create negative spin-orbit splitting and so a finite insulating gap. Subject 3 Unconventional spin textures of TI surface states: Despite the fact that one of our predicted TI-1 KBaBi has inversion symmetry in the bulk-a fact that that would preclude bulk spin polarization-we find a Dresselhaus-like spin texture with non-helical spin texture. This originates from the local spin polarization, anchored on the atomic sites with inversion asymmetric point groups, that is compensated due to global inversion symmetry in bulk. In collaboration with: Jun-Wei Luo, Qihang Liu

  12. The Behavior of Indonesian Stock Market: Structural Breaks and Nonlinearity

    Directory of Open Access Journals (Sweden)

    Rahmat Heru Setianto

    2011-09-01

    Full Text Available This study empirically examines the behaviour of Indonesian stock market under the efficient market hypothesis framework by emphasizing on the random walk behaviour and nonlinearity over the period of April 1983 - December 2010. In the first step, the standard linear unit root test, namely the augmented Dickey-Fuller (ADF test, Phillip-Perron (PP test and Kwiatkowski-Philllips-Schmidt-Shin (KPSS test identify the random walk behaviour in the indices. In order to take account the possible breaks in the index series Zivot and Adrews (1992 one break and Lumsdaine and Papell (1997 two breaks unit root test are employed to observe whether the presence of breaks in the data series will prevent the stocks from randomly pricing or vice versa. In the third step, we employ Harvey et al. (2008 test to examine the presence of nonlinear behaviour in Indonesian stock indices. The evidence of nonlinear behaviour in the indices, motivate us to use nonlinear unit root test procedure recently developed by Kapetanios et al. (2003 and Kruse (2010. In general, the results from standard linear unit root test, Zivot and Adrews (ZA test and Lumsdaine and Papell (LP test provide evidence that Jakarta Composite Index characterized by a unit root. In addition, structural breaks identified by ZA and LP test are corresponded to the events of financial market liberalization and financial crisis. The nonlinear unit root test procedure fail to rejects the null hypothesis of unit root for all indices, suggesting that Jakarta Composite Index characterized by random walk process supporting the theory of efficient market hypothesis.

  13. An exact solution for the history-dependent material and delamination behavior of laminated plates subjected to cylindrical bending

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Todd O [Los Alamos National Laboratory

    2009-01-01

    The exact solution for the history-dependent behavior of laminated plates subjected to cylindrical bending is presented. The solution represents the extension of Pagano's solution to consider arbitrary types of constitutive behaviors for the individual lamina as well as arbitrary types of cohesive zones models for delamination behavior. Examples of the possible types of material behavior are plasticity, viscoelasticity, viscoplasticity, and damaging. Examples of possible CZMs that can be considered are linear, nonlinear hardening, as well as nonlinear with softening. The resulting solution is intended as a benchmark solution for considering the predictive capabilities of different plate theories. Initial results are presented for several types of history-dependent material behaviors. It is shown that the plate response in the presence of history-dependent behaviors can differ dramatically from the elastic response. These results have strong implications for what constitutes an appropriate plate theory for modeling such behaviors.

  14. Oscillatory and Asymptotic Behavior of a Second-Order Nonlinear Functional Differential Equations

    Institute of Scientific and Technical Information of China (English)

    张全信; 高丽; 王少英

    2012-01-01

    This paper is concerned with oscillatory and asymptotic behavior of solutions of a class of second order nonlinear functional differential equations. By using the generalized Riccati transformation and the integral averaging technique, new oscillation criteria and asymptotic behavior are obtained for all solutions of the equation. Our results generalize and improve some known theorems.

  15. Stable Second-Order Nonlinear Optical Materials Based on Interpenetrating Polymer Networks

    Science.gov (United States)

    1994-03-17

    0IJUN93 to 31MAY94 4. 1I1Lk ANDLSUBI1ILIE D. ?-UNUING NUMBERS •’• Stable Second-Order Nonlinear Optical Materials Based On C:N00014-90-J-1148...release and sale; its distribution is unlimited. I Stable Second-Order Nonlinear Optical Materials Based On Interpenetrating Polymer Networks S... Optical Materials Based On Interpenetrating Polymer Networks by S. Marturunkakul, J. I. Chen, L. Li, X. L. Jiang, R. J. Jeng, S. K. Sengupta, J. Kumar

  16. A thermodynamic approach to nonlinear ultrasonics for material state awareness and prognosis

    CERN Document Server

    Chillara, Vamshi Krishna

    2016-01-01

    We develop a thermodynamic framework for modeling nonlinear ultrasonic damage sensing and prognosis in materials undergoing progressive damage. The framework is based on the internal variable approach and relies on the construction of a pseudo-elastic strain energy function that captures the energetics associated with the damage progression. The pseudo-elastic strain energy function is composed of two energy functions - one that describes how a material stores energy in an elastic fashion and the other describes how material dissipates energy or stores it in an inelastic fashion. Experimental motivation for the choice of the above two functionals is discussed and some specific choices pertaining to damage progression during fatigue and creep are presented. The thermodynamic framework is employed to model the nonlinear response of material undergoing stress relaxation and creep-like degradation. For each of the above cases, evolution of the nonlinearity parameter with damage as well as with macroscopic measura...

  17. {open_quotes}Quadrupoled{close_quotes} materials for second-order nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, S.F.; Petschek, R.G.; Singer, K.D. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics] [and others

    1997-10-01

    We describe a new approach to second-order nonlinear optical materials, namely quadrupoling. This approach is valid in the regime of Kleinman (full permutation) symmetry breaking, and thus requires a two- or three dimensional microscopic nonlinearity at wavelengths away from material resonances. This {open_quotes}quadrupolar{close_quotes} nonlinearity arises from the second rank pseudotensor of the rotationally invariant representation of the second-order nonlinear optical tensor. We have experimentally investigated candidate molecules comprised of chiral camphorquinone derivatives by measuring the scalar invariant associated with the rank two pseudotensor using hyper-Rayleigh scattering. We have found sizable scalar figures of merit for several compounds using light for which the second harmonic wavelengths are greater than 100 nm longer than the absorption peak location. At these wavelengths, the quadrupolar scalar is as large as the polar (EFISH) scalar of p-nitroaniline. Prospects for applications are discussed.

  18. Synthesis, characterization and third-order nonlinear optical properties of symmetrical ferrocenyl Schiff base materials

    Science.gov (United States)

    Yu, Weiguo; Jia, Jianhong; Gao, Jianrong; Han, Liang; Li, Yujin

    2015-03-01

    Six symmetrical ferrocenyl Schiff base materials were synthesized and characterized by UV, 1H NMR, mass spectrometry (MS) and elemental analysis. Their off-resonant third-order nonlinear optical properties were measured using femtosecond laser and degenerate four-wave mixing (DFWM) technique. The third-order nonlinear optical susceptibilities χ(3) were 1.961-6.363 × 10-13 esu. The nonlinear refractive indexes n2 were 3.609-11.716 × 10-12 esu. The second-order hyperpolarizabilities γ of these molecules were 1.967-6.388 × 10-31 esu. The response time were 45.759-73.079 fs. The results indicate that these materials have potential nonlinear optical applications.

  19. Third harmonic generation as a rapid selection tool for organic materials for nonlinear integrated optics devices

    NARCIS (Netherlands)

    Blom, F.C.; Driessen, A.; Hoekstra, Hugo; van Schoot, J.B.P.; van Schoot, Jan B.P.; Popma, T.J.A.

    1999-01-01

    In the long trajectory from the synthesis of organic nonlinear optical materials to the completed all-optical device it is highly desirable to be able to concentrate already in an early state on only a few promising materials. Third harmonic generation (THG) is a very convenient method as it allows

  20. Third harmonic generation as a rapid selection tool for organic materials for nonlinear integrated optics devices

    NARCIS (Netherlands)

    Blom, Freek C.; Driessen, Alfred; Hoekstra, Hugo J.W.M.; Schoot, van Jan B.P.; Popma, Th.J.A.

    1999-01-01

    In the long trajectory from the synthesis of organic nonlinear optical materials to the completed all-optical device it is highly desirable to be able to concentrate already in an early state on only a few promising materials. Third harmonic generation (THG) is a very convenient method as it allows

  1. An exact approach to intensity analysis of optical pulses in nonlinear meta-materials

    Science.gov (United States)

    Nanda, Lipsa

    2016-05-01

    The nonlinear pulse propagation has been analytically studied by solving the nonlinear Schrödinger's equation (NLSE) in bulk media exhibiting frequency dependent dielectric permittivity(ɛ) and magnetic permeability(μ). The exact solutions obtained are shown to be of trigonometric & localized types. The analytical and simulation based method has been further extended to investigate the intensity distribution in a nonlinear meta-material which behaves as a negative refractive medium (NRM), where both ɛ and μ are shown to be dispersive and negative in nature.

  2. Swarming behaviors in multi-agent systems with nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wenwu, E-mail: wenwuyu@gmail.com [Department of Mathematics, Southeast University, Nanjing 210096 (China); School of Electrical and Computer Engineering, RMIT University, Melbourne VIC 3001 (Australia); Chen, Guanrong [Department of Electronic Engineering, City University of Hong Kong, Hong Kong (China); Cao, Ming [Faculty of Mathematics and Natural Sciences, ITM, University of Groningen (Netherlands); Lü, Jinhu [Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, Hai-Tao [Department of Control Science and Engineering, State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-12-15

    The dynamic analysis of a continuous-time multi-agent swarm model with nonlinear profiles is investigated in this paper. It is shown that, under mild conditions, all agents in a swarm can reach cohesion within a finite time, where the upper bounds of the cohesion are derived in terms of the parameters of the swarm model. The results are then generalized by considering stochastic noise and switching between nonlinear profiles. Furthermore, swarm models with limited sensing range inducing changing communication topologies and unbounded repulsive interactions between agents are studied by switching system and nonsmooth analysis. Here, the sensing range of each agent is limited and the possibility of collision among nearby agents is high. Finally, simulation results are presented to demonstrate the validity of the theoretical analysis.

  3. Nonlinear dynamical behavior of shallow cylindrical reticulated shells

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-zhi; LIANG Cong-xing; HAN Ming-jun; YEH Kai-yuan; WANG Gang

    2007-01-01

    By using the method of quasi-shells , the nonlinear dynamic equations of three-dimensional single-layer shallow cylindrical reticulated shells with equilateral triangle cell are founded. By using the method of the separating variable function, the transverse displacement of the shallow cylindrical reticulated shells is given under the conditions of two edges simple support. The tensile force is solved out from the compatible equations, a nonlinear dynamic differential equation containing second and third order is derived by using the method of Galerkin. The stability near the equilibrium point is discussed by solving the Floquet exponent and the critical condition is obtained by using Melnikov function. The existence of the chaotic motion of the single-layer shallow cylinmapping.

  4. Swarming behaviors in multi-agent systems with nonlinear dynamics.

    Science.gov (United States)

    Yu, Wenwu; Chen, Guanrong; Cao, Ming; Lü, Jinhu; Zhang, Hai-Tao

    2013-12-01

    The dynamic analysis of a continuous-time multi-agent swarm model with nonlinear profiles is investigated in this paper. It is shown that, under mild conditions, all agents in a swarm can reach cohesion within a finite time, where the upper bounds of the cohesion are derived in terms of the parameters of the swarm model. The results are then generalized by considering stochastic noise and switching between nonlinear profiles. Furthermore, swarm models with limited sensing range inducing changing communication topologies and unbounded repulsive interactions between agents are studied by switching system and nonsmooth analysis. Here, the sensing range of each agent is limited and the possibility of collision among nearby agents is high. Finally, simulation results are presented to demonstrate the validity of the theoretical analysis.

  5. Asymptotic Behavior of Solutions for Nonlinear Volterra Discrete Equations

    Directory of Open Access Journals (Sweden)

    E. Messina

    2008-01-01

    Full Text Available We consider nonlinear difference equations of unbounded order of the form xi=bi−∑j=0iai,jfi−j(xj,  i=0,1,2,…, where fj(x  (j=0,…,i are suitable functions. We establish sufficient conditions for the boundedness and the convergence of xi as i→+∞. Some of these conditions are interesting mainly for studying stability of numerical methods for Volterra integral equations.

  6. Analysis of fractional non-linear diffusion behaviors based on Adomian polynomials

    Directory of Open Access Journals (Sweden)

    Wu Guo-Cheng

    2017-01-01

    Full Text Available A time-fractional non-linear diffusion equation of two orders is considered to investigate strong non-linearity through porous media. An equivalent integral equation is established and Adomian polynomials are adopted to linearize non-linear terms. With the Taylor expansion of fractional order, recurrence formulae are proposed and novel numerical solutions are obtained to depict the diffusion behaviors more accurately. The result shows that the method is suitable for numerical simulation of the fractional diffusion equations of multi-orders.

  7. Nonlinear behavior of electron acoustic waves in an un-magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Manjistha; Khan, Manoranjan [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Roychoudhury, Rajkumar [Indian Statistical Institute, Kolkata 700 108 (India)

    2011-10-15

    The nonlinear electron acoustic wave, which is found in the earth's magnetosphere by satellite observations, is studied analytically by Lagrangian fluid description. The basic linear mode is observed in a two temperature electron species plasma where ions form stationary charge neutral background. We have obtained nonlinear description of this mode, which depends on both time and space. A possible solution shows a soliton like structure, which is localized in space, and the amplitude increases with time in the absence of dispersion. Small dispersive correction, however, shows spread of the solution in space. This method can be generalized to study the nonlinear behavior of a general class of multispecies plasma.

  8. Analysis of linear elasticity and non-linearity due to plasticity and material damage in woven and biaxial braided composites

    Science.gov (United States)

    Goyal, Deepak

    Textile composites have a wide variety of applications in the aerospace, sports, automobile, marine and medical industries. Due to the availability of a variety of textile architectures and numerous parameters associated with each, optimal design through extensive experimental testing is not practical. Predictive tools are needed to perform virtual experiments of various options. The focus of this research is to develop a better understanding of linear elastic response, plasticity and material damage induced nonlinear behavior and mechanics of load flow in textile composites. Textile composites exhibit multiple scales of complexity. The various textile behaviors are analyzed using a two-scale finite element modeling. A framework to allow use of a wide variety of damage initiation and growth models is proposed. Plasticity induced non-linear behavior of 2x2 braided composites is investigated using a modeling approach based on Hill's yield function for orthotropic materials. The mechanics of load flow in textile composites is demonstrated using special non-standard postprocessing techniques that not only highlight the important details, but also transform the extensive amount of output data into comprehensible modes of behavior. The investigations show that the damage models differ from each other in terms of amount of degradation as well as the properties to be degraded under a particular failure mode. When compared with experimental data, predictions of some models match well for glass/epoxy composite whereas other's match well for carbon/epoxy composites. However, all the models predicted very similar response when damage factors were made similar, which shows that the magnitude of damage factors are very important. Full 3D as well as equivalent tape laminate predictions lie within the range of the experimental data for a wide variety of braided composites with different material systems, which validated the plasticity analysis. Conclusions about the effect of

  9. Mathematical modeling of materially nonlinear problems in structural analyses, Part II: Application in contemporary software

    Directory of Open Access Journals (Sweden)

    Bonić Zoran

    2010-01-01

    Full Text Available The paper presents application of nonlinear material models in the software package Ansys. The development of the model theory is presented in the paper of the mathematical modeling of material nonlinear problems in structural analysis (part I - theoretical foundations, and here is described incremental-iterative procedure for solving problems of nonlinear material used by this package and an example of modeling of spread footing by using Bilinear-kinematics and Drucker-Prager mode was given. A comparative analysis of the results obtained by these modeling and experimental research of the author was made. Occurrence of the load level that corresponds to plastic deformation was noted, development of deformations with increasing load, as well as the distribution of dilatation in the footing was observed. Comparison of calculated and measured values of reinforcement dilatation shows their very good agreement.

  10. Material and Geometric Nonlinear Analysis of Functionally Graded Plate-Shell Type Structures

    Science.gov (United States)

    Moita, J. S.; Araújo, A. L.; Mota Soares, C. M.; Mota Soares, C. A.; Herskovits, J.

    2016-08-01

    A nonlinear formulation for general Functionally Graded Material plate-shell type structures is presented. The formulation accounts for geometric and material nonlinear behaviour of these structures. Using the Newton-Raphson incremental-iterative method, the incremental equilibrium path is obtained, and in case of snap-through occurrence the automatic arc-length method is used. This simple and fast element model is a non-conforming triangular flat plate/shell element with 24 degrees of freedom for the generalized displacements. It is benchmarked in the solution of some illustrative plate- shell examples and the results are presented and discussed with numerical alternative models. Benchmark tests with material and geometrically nonlinear behaviour are also proposed.

  11. Material nonlinear analysis via mixed-iterative finite element method

    Science.gov (United States)

    Sutjahjo, Edhi; Chamis, Christos C.

    1992-01-01

    The performance of elastic-plastic mixed-iterative analysis is examined through a set of convergence studies. Membrane and bending behaviors are tested using 4-node quadrilateral finite elements. The membrane result is excellent, which indicates the implementation of elastic-plastic mixed-iterative analysis is appropriate. On the other hand, further research to improve bending performance of the method seems to be warranted.

  12. Nonlinear conductive properties and scaling behavior of conductive particle filled high-density polyethylene composites

    Institute of Scientific and Technical Information of China (English)

    ZHENG Qiang; SHEN Lie; LI Wenchun; SONG Yihu; YI Xiaosu

    2005-01-01

    The blends prepared by incorporation of carbon black (CB) or graphite powder (GP) inHto high-density polyethylene (HDPE) matrix have been novel and extensively applied polymeric positive temperature coefficient (PTC) composites. A phenomenological model was proposed on the basis of the GEM equation and the dilution effect of filler volume fraction due to the thermal volume expansion of the polymer matrix. Accordingly, the contribution of the thermal expansion of the matrix to the jump-like PTC transition of the composites was quantitatively estimated and a mechanical explanation was given. It was proved that the contribution of the volume expansion to PTC effect decreased for HDPE/CB composites crosslinked through electron-beam irradiation. Furthermore, the influences of the filler content, temperature and crosslinking on the self-heating behavior as well as the nonlinear conduction characteristics at electrical-thermal equilibrium state were examined. Based on the electric-field and initial resistivity dependence of the self-heating temperature and resistance dependence of the critical field, the mechanisms of the self-heating of the polymeric PTC materials were evaluated. The intrinsic relations between macroscopic electrical properties and microscopic percolation network at electrical-thermal equilibrium state were discussed according to the scaling relationship between the self-heating critical parameter and the conductivity of materials.

  13. Growth and Study of Nonlinear Optical Materials for Frequency Conversion Devices with Applications in Defense and Security

    Science.gov (United States)

    2015-03-01

    AFRL-RY-WP-TP-2015-0068 GROWTH AND STUDY OF NONLINEAR OPTICAL MATERIALS FOR FREQUENCY CONVERSION DEVICES WITH APPLICATIONS IN DEFENCE AND...2015 Technical Paper 1 August 2013 – 1 August 2014 4. TITLE AND SUBTITLE GROWTH AND STUDY OF NONLINEAR OPTICAL MATERIALS FOR FREQUENCY CONVERSION...SUBJECT TERMS hydride vapor phase epitaxy, nonlinear optical materials , quasi-phase matching 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

  14. Nonlinear Dynamical Behavior in BS Evolution Model Based on Small-World Network Added with Nonlinear Preference

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ying-Yue; YANG Qiu-Ying; CHEN Tian-Lun

    2007-01-01

    We introduce a modified small-world network adding new links with nonlinearly preferential connection instead of adding randomly, then we apply Bak-Sneppen (BS) evolution model on this network. We study several important structural properties of our network such as the distribution of link-degree, the maximum link-degree, and the length of the shortest path. We further argue several dynamical characteristics of the model such as the important critical value fc, the f0 avalanche, and the mutating condition, and find that those characteristics show particular behaviors.

  15. On the Prediction of the Nonlinear Absorption in Reverse Saturable Absorbing Materials

    Science.gov (United States)

    Pachter, Ruth; Nguyen, Kiet A.; Day, Paul N.; Kennel, Joshua C.

    2001-03-01

    In our continuing efforts to design materials that exhibit reverse saturable absorption (RSA), we systematically examine the ability of the time-dependent density functional theory (TDDFT) method using local, nonlocal, and hybrid functionals, to predict the experimental nonlinear absorption for a variety of organic and organometallic molecular systems, including a number of free-base porphyrins, phthalocyanine and their metal complexes. The ground and triplet-triplet excitation energies, as well as the oscillator strengths are calculated, indicating good agreement with experiment. We conclude that the TDDFT approach with a hybrid functional provides good estimates for the nonlinear absorption of RSA materials.

  16. Wave propagation in parallel-plate waveguides filled with nonlinear left-handed material

    Institute of Scientific and Technical Information of China (English)

    Burhan Zamir; Rashid Ali

    2011-01-01

    A theoretical investigation of field components for transverse electric mode in the parallel-plate waveguides has been studied. In this analysis two different types of waveguide structures have been discussed, i.e., (a) normal good/perfect conducting parallel-plate waveguide filled with nonlinear left-handed material and (b) high-temperature-superconducting parallel-plate waveguide filled with nonlinear left-handed material. The dispersion relations of transverse electric mode have also been discussed for these two types of waveguide structures.

  17. Chip scale low dimensional materials: optoelectronics & nonlinear optics

    Science.gov (United States)

    Gu, Tingyi

    The CMOS foundry infrastructure enables integration of high density, high performance optical transceivers. We developed integrated devices that assemble resonators, waveguide, tapered couplers, pn junction and electrodes. Not only the volume standard manufacture in silicon foundry is promising to low-lost optical components operating at IR and mid-IR range, it also provides a robust platform for revealing new physical phenomenon. The thesis starts from comparison between photonic crystal and micro-ring resonators based on chip routers, showing photonic crystal switches have small footprint, consume low operation power, but its higher linear loss may require extra energy for signal amplification. Different designs are employed in their implementation in optical signal routing on chip. The second part of chapter 2 reviews the graphene based optoelectronic devices, such as modulators, lasers, switches and detectors, potential for group IV optoelectronic integrated circuits (OEIC). In chapter 3, the highly efficient thermal optic control could act as on-chip switches and (transmittance) tunable filters. Local temperature tuning compensates the wavelength differences between two resonances, and separate electrode is used for fine tuning of optical pathways between two resonators. In frequency domain, the two cavity system also serves as an optical analogue of Autler-Towns splitting, where the cavity-cavity resonance detuning is controlled by the length of pathway (phase) between them. The high thermal sensitivity of cavity resonance also effectively reflects the heat distribution around the nanoheaters, and thus derives the thermal conductivity in the planar porous suspended silicon membrane. Chapter 4 & 5 analyze graphene-silicon photonic crystal cavities with high Q and small mode volume. With negligible nonlinear response to the milliwatt laser excitation, the monolithic silicon PhC turns into highly nonlinear after transferring the single layer graphene with

  18. Comment on "Nonlinear refraction measurements of materials using the moiré deflectometry"

    Science.gov (United States)

    Rashidian Vaziri, M. R.

    2015-12-01

    In an influential paper Jamshidi-Ghaleh and Mansour [1] (Opt. Commun. 234 (2004) 419), have reported on a new method for measuring the nonlinear refractive index of materials using the rotational moiré deflectometry technique. In the cited work, the authors apply the ray matrix theory for finding the beam deflection angle on the plane of the first grating in the used geometry. To this end, using the parabolic approximation, the exponential term in the beam irradiance is expanded and retaining the first two resultant terms, the nonlinear sample is treated as a thin lens with a position dependent focal length. In this comment, the effective focal length of the nonlinear sample has been rederived in detail using the Gaussian beam theory and it is shown that it must contain a correction factor. The relative error introduced by ignoring this factor can be as large as 73.5-84.4% in determining the nonlinear refractive index of thin samples.

  19. Organic nonlinear optical materials: where we have been and where we are going.

    Science.gov (United States)

    Marder, Seth R

    2006-01-14

    Nonlinear optical (NLO) materials can be useful for a variety of applications varying from modulation of optical signals facilitated by the electro-optic effect-the effect whereby the refractive index of a material changes in response to an applied electric field-to microfabrication, sensing, imaging, and cancer therapy facilitated by multiphoton absorption, wherein molecules simultaneously absorb two or more photons of light. This short Focus article is a brief personal perspective of some of the key advances in second-order NLO materials and in multiphoton-absorbing materials, and of how and why these advances have led to renewed interest in organic NLO materials.

  20. Fatigue Life Prediction of Metallic Materials Based on the Combined Nonlinear Ultrasonic Parameter

    Science.gov (United States)

    Zhang, Yuhua; Li, Xinxin; Wu, Zhenyong; Huang, Zhenfeng; Mao, Hanling

    2017-07-01

    The fatigue life prediction of metallic materials is always a tough problem that needs to be solved in the mechanical engineering field because it is very important for the secure service of mechanical components. In this paper, a combined nonlinear ultrasonic parameter based on the collinear wave mixing technique is applied for fatigue life prediction of a metallic material. Sweep experiments are first conducted to explore the influence of driving frequency on the interaction of two driving signals and the fatigue damage of specimens, and the amplitudes of sidebands at the difference frequency and sum frequency are tracked when the driving frequency changes. Then, collinear wave mixing tests are carried out on a pair of cylindrically notched specimens with different fatigue damage to explore the relationship between the fatigue damage and the relative nonlinear parameters. The experimental results show when the fatigue degree is below 65% the relative nonlinear parameter increases quickly, and the growth rate is approximately 130%. If the fatigue degree is above 65%, the increase in the relative nonlinear parameter is slow, which has a close relationship with the microstructure evolution of specimens. A combined nonlinear ultrasonic parameter is proposed to highlight the relationship of the relative nonlinear parameter and fatigue degree of specimens; the fatigue life prediction model is built based on the relationship, and the prediction error is below 3%, which is below the prediction error based on the relative nonlinear parameters at the difference and sum frequencies. Therefore, the combined nonlinear ultrasonic parameter using the collinear wave mixing method can effectively estimate the fatigue degree of specimens, which provides a fast and convenient method for fatigue life prediction.

  1. Fatigue Life Prediction of Metallic Materials Based on the Combined Nonlinear Ultrasonic Parameter

    Science.gov (United States)

    Zhang, Yuhua; Li, Xinxin; Wu, Zhenyong; Huang, Zhenfeng; Mao, Hanling

    2017-08-01

    The fatigue life prediction of metallic materials is always a tough problem that needs to be solved in the mechanical engineering field because it is very important for the secure service of mechanical components. In this paper, a combined nonlinear ultrasonic parameter based on the collinear wave mixing technique is applied for fatigue life prediction of a metallic material. Sweep experiments are first conducted to explore the influence of driving frequency on the interaction of two driving signals and the fatigue damage of specimens, and the amplitudes of sidebands at the difference frequency and sum frequency are tracked when the driving frequency changes. Then, collinear wave mixing tests are carried out on a pair of cylindrically notched specimens with different fatigue damage to explore the relationship between the fatigue damage and the relative nonlinear parameters. The experimental results show when the fatigue degree is below 65% the relative nonlinear parameter increases quickly, and the growth rate is approximately 130%. If the fatigue degree is above 65%, the increase in the relative nonlinear parameter is slow, which has a close relationship with the microstructure evolution of specimens. A combined nonlinear ultrasonic parameter is proposed to highlight the relationship of the relative nonlinear parameter and fatigue degree of specimens; the fatigue life prediction model is built based on the relationship, and the prediction error is below 3%, which is below the prediction error based on the relative nonlinear parameters at the difference and sum frequencies. Therefore, the combined nonlinear ultrasonic parameter using the collinear wave mixing method can effectively estimate the fatigue degree of specimens, which provides a fast and convenient method for fatigue life prediction.

  2. Theoretical prediction of electrocaloric effect based on non-linear behaviors of dielectric permittivity under temperature and electric fields

    Directory of Open Access Journals (Sweden)

    Hongbo Liu

    2015-11-01

    Full Text Available The electrocaloric (EC effect has been paid great attentions recently for applications on cooling or electricity generation. However, the directly commercial measurement equipment for the effect is still unavailable. Here we report a novel method to predict EC effect by non-linear behaviors of dielectric permittivity under temperature and electric fields. According to the method, the analytical equations of EC temperature change ΔT are directly given for normal ferroelectrics and relaxor. The calculations have been performed on several materials and it is shown that the method is suitable for both inorganic and organic ferroelectrics, and relaxor.

  3. Understanding of flux-limited behaviors of heat transport in nonlinear regime

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yangyu, E-mail: yangyuhguo@gmail.com [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084 (China); Jou, David, E-mail: david.jou@uab.es [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Wang, Moran, E-mail: mrwang@tsinghua.edu [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084 (China)

    2016-01-28

    The classical Fourier's law of heat transport breaks down in highly nonequilibrium situations as in nanoscale heat transport, where nonlinear effects become important. The present work is aimed at exploring the flux-limited behaviors based on a categorization of existing nonlinear heat transport models in terms of their theoretical foundations. Different saturation heat fluxes are obtained, whereas the same qualitative variation trend of heat flux versus exerted temperature gradient is got in diverse nonlinear models. The phonon hydrodynamic model is proposed to act as a standard to evaluate other heat flux limiters because of its more rigorous physical foundation. A deeper knowledge is thus achieved about the phenomenological generalized heat transport models. The present work provides deeper understanding and accurate modeling of nonlocal and nonlinear heat transport beyond the diffusive limit. - Highlights: • Exploring flux-limited behaviors based on a categorization of existing nonlinear heat transport models. • Proposing phonon hydrodynamic model as a standard to evaluate heat flux limiters. • Providing accurate modeling of nonlocal and nonlinear heat transport beyond the diffusive limit.

  4. PATH INTEGRAL SOLUTION OF NONLINEAR DYNAMIC BEHAVIOR OF STRUCTURE UNDER WIND EXCITATION

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A numerical scheme for the nonlinear behavior of structure under wind excitation is investigated. With the white noise filter of turbulent-wind fluctuations, the nonlinear motion equation of structures subjected to wind load was modeled as the Ito' s stochastic differential equation. The state vector associated with such a model is a diffusion process. A continuous linearization strategy in the time-domain was adopted.Based on the solution series of its stochastic linearization equations, the formal probabilistic density of the structure response was developed by the path integral technique. It is shown by the numerical example of a guyed mast that compared with the frequency-domain method and the time-domain nonlinear analysis, the proposed approach is highlighted by high accuracy and effectiveness. The influence of the structure non-linearity on the dynamic reliability assessment is also analyzed in the example.

  5. Ambiguities in input-output behavior of driven nonlinear systems close to bifurcation

    Directory of Open Access Journals (Sweden)

    Reit Marco

    2016-06-01

    Full Text Available Since the so-called Hopf-type amplifier has become an established element in the modeling of the mammalian hearing organ, it also gets attention in the design of nonlinear amplifiers for technical applications. Due to its pure sinusoidal response to a sinusoidal input signal, the amplifier based on the normal form of the Andronov-Hopf bifurcation is a peculiar exception of nonlinear amplifiers. This feature allows an exact mathematical formulation of the input-output characteristic and thus deeper insights of the nonlinear behavior. Aside from the Hopf-type amplifier we investigate an extension of the Hopf system with focus on ambiguities, especially the separation of solution sets, and double hysteresis behavior in the input-output characteristic. Our results are validated by a DSP implementation.

  6. Non-linear modeling of active biohybrid materials

    KAUST Repository

    Paetsch, C.

    2013-11-01

    Recent advances in engineered muscle tissue attached to a synthetic substrate motivate the development of appropriate constitutive and numerical models. Applications of active materials can be expanded by using robust, non-mammalian muscle cells, such as those of Manduca sexta. In this study, we propose a model to assist in the analysis of biohybrid constructs by generalizing a recently proposed constitutive law for Manduca muscle tissue. The continuum model accounts (i) for the stimulation of muscle fibers by introducing multiple stress-free reference configurations for the active and passive states and (ii) for the hysteretic response by specifying a pseudo-elastic energy function. A simple example representing uniaxial loading-unloading is used to validate and verify the characteristics of the model. Then, based on experimental data of muscular thin films, a more complex case shows the qualitative potential of Manduca muscle tissue in active biohybrid constructs. © 2013 Elsevier Ltd. All rights reserved.

  7. Thermodynamics and nonlinear mechanics of materials with photoresponsive microstructure

    Science.gov (United States)

    Oates, William S.; Bin, Jonghoon

    2014-03-01

    The ability to directly convert visible light radiation into useful mechanical work provides many opportunities in the field of smart materials and adaptive structures ranging from biomedical applications to control of heliostat mirrors for solar harvesting. The complexities associated with coupling time-dependent Maxwell's equations with linear momentum and mechanics is discussed by introducing a set of electronic order parameters that govern the coupling between electromagnetic radiation and mechanics of a deformable solid. Numerical examples are given illustrating how this methodology is applied to a special class of liquid crystal polymer networks containing azobenzene. The dynamics associated with light absorption and its effect on deformation of the polymer are solved in three dimensions using finite difference methods and compared to experimental results. Particular emphasis is placed on the effect of polarized light on microstructure evolution and stresses that occur during photoisomerization of the optically active microstructure.

  8. Mesomorphic glass nanocomposites made of metal alkanoates and nanoparticles as emerging nonlinear-optical materials

    Science.gov (United States)

    Garbovskiy, Y.; Klimusheva, G.; Mirnaya, T.

    2016-09-01

    Mesomorphic metal alkanoates is very promising yet overlooked class of nonlinear-optical materials. Metal alkanoates can exhibit a broad variety of condensed states of matter including solid crystals, plastic crystals, lyotropic and thermotropic ionic liquid crystals, liquids, mesomorphic glasses, and Langmuir-Blodgett films. Glass-forming properties of metal alkanoates combined with their use as nano-reactors and anisotropic host open up simple and efficient way to design various photonic nanomaterials. Despite very interesting physics, the experimental data on optical and nonlinearoptical properties of such materials are scarce. The goal of the present paper is to fill the gap by discussing recent advances in the field of photonic materials made of metal alkanoates, organic dyes, and nanoparticles. Optical and nonlinear-optical properties of the following materials are reviewed: (i) mesomorphic glass doped with organic dyes; (ii) smectic glass composed of cobalt alkanoates; (iii) semiconductor nanoparticles embedded in a glassy host; (iv) metal nanoparticles - glass (the cobalt octanoate) nanocomposites.

  9. Existence of solutions for quasistatic problems of unilateral contact with nonlocal friction for nonlinear elastic materials

    Directory of Open Access Journals (Sweden)

    Alain Mignot

    2005-09-01

    Full Text Available This paper shows the existence of a solution of the quasi-static unilateral contact problem with nonlocal friction law for nonlinear elastic materials. We set up a variational incremental problem which admits a solution, when the friction coefficient is small enough, and then by passing to the limit with respect to time we obtain a solution.

  10. A new approach of binary addition and subtraction by non-linear material based switching technique

    Indian Academy of Sciences (India)

    Archan Kumar Das; Partha Partima Das; Sourangshu Mukhopadhyay

    2005-02-01

    Here, we refer a new proposal of binary addition as well as subtraction in all-optical domain by exploitation of proper non-linear material-based switching technique. In this communication, the authors extend this technique for both adder and subtractor accommodating the spatial input encoding system.

  11. Predicting the dielectric nonlinearity of anisotropic composite materials via tensorial analysis

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, S [Department of Physics, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato (Italy); Rocchia, W [NEST CNR-INFM, Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy)

    2006-11-29

    The discovery of new materials with peculiar optical properties as well as the prediction of their behaviour given the microstructure is a matter of remarkable interest in the community of material scientists. A complete theory allowing such a prediction is not yet available. We have formulated a theory able to analytically predict the effective second- and third-order nonlinear electrical behaviour of a dilute dispersion of randomly oriented anisotropic nonlinear spheres in a linear host. The inclusion medium has non-vanishing second- and third-order nonlinear hypersusceptibilities. As a result, the overall composite material is nonlinear but isotropic because of the random orientation of the inclusions. We derive the expressions for the equivalent permittivity and for the Kerr equivalent hypersusceptibility in terms of the characteristic electric tensors describing the electrical behaviour of the spheres. The complete averaging over inclusion positions and orientations led to general results in the dilute limit. We show that these results are consistent with earlier theories and that they provide null second-order hypersusceptibility as expected in a macroscopically isotropic medium. This theory generalizes the well-known Maxwell-Garnett formula and it can be easily specialized to any of the 32 crystallographic symmetry classes. Despite this study assuming static conditions, it can be generalized to the sinusoidal regime, pointing at an interesting way to engineer optically active materials with desired behaviour.

  12. Experimental observations of the characteristics of hot electron and nonlinear processes produced in special material

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Making use of disk targets composed of several peculiar materials (foam Au, foam C8H8)and hohlraum with a special structure, experiments have been done at"Xing Guang - II" laser facility,which study the characteristics of hot electrons and therelated nonlinear processes such as StimulatedRaman Scattering (SRS), Two Plasma Decay (TPD), StimulatedBrillouin Scattering (SBS), etc.

  13. Analysis of the nonlinear behavior of adhesives in bonded assemblies - Comparison of TAST and Arcan tests

    OpenAIRE

    Cognard, J; Creac' Hcadec, R; Sohier, L; Davies, Peter

    2008-01-01

    This paper describes a study in which the shear behavior of a structural epoxy adhesive has been measured using the standard thick adherend shear test (TAST) specimen and a modified Arcan test A. numerical study of the TAST test taking into account the nonlinear behavior of the adhesive and the finite deformations of the adhesive joint, shows that there is a localization of plastic zones close to the adhesive-substrate interface near the free edge of the adhesive. Experimental tests carried o...

  14. Nonlinear Dynamical Behavior in Neuron Model Based on Small World Network with Attack and Repair Strategy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue; YANG Qiu-Ying; ZHENG Tai-Yu; ZHANG Ying-Yue; ZHENG Li; ZHANG Gui-Qing; CHEN Tian-Lun

    2008-01-01

    In this paper, we investigate the effect due to the change of topology structure of network on the nonlinear dynamical behavior, by virtue of the OFC neuron evolution model with attack and repair strategy based on the small world. In particular, roles of various parameters relating to the dynamical behavior are carefully studied and analyzed. In addition, the avalanche and EEG-like wave activities with attack and repair strategy are also explored in detail in this work.

  15. Nanomodeling of Nonlinear Thermoelastic Behavior of AA5454/ Silicon Nitride Nanoparticulate Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    Chennakesava R Alavala

    2016-01-01

    Full Text Available The aim of the present work was to estimate non-linear thermoelastic behavior of three-phase AA5454/silicon nitride nanoparticle metal matrix composites. The thermal loading was varied from subzero temperature to under recrystallization temperature. The RVE models were used to analyze thermo-elastic behavior. The AA5454/silicon nitride nanoparticle metal matrix composites have gained the elastic modulus below 0oC and lost at high temperatures.

  16. Complex Nonlinear Behavior in Metabolic Processes: Global Bifurcation Analysis of Escherichia coli Growth on Multiple Substrates

    Directory of Open Access Journals (Sweden)

    Hyun-Seob Song

    2013-09-01

    Full Text Available The nonlinear behavior of metabolic systems can arise from at least two different sources. One comes from the nonlinear kinetics of chemical reactions in metabolism and the other from nonlinearity associated with regulatory processes. Consequently, organisms at a constant growth rate (as experienced in a chemostat could display multiple metabolic states or display complex oscillatory behavior both with potentially serious implications to process operation. This paper explores the nonlinear behavior of a metabolic model of Escherichia coli growth on mixed substrates with sufficient detail to include regulatory features through the cybernetic postulate that metabolic regulation is the consequence of a dynamic objective function ensuring the organism’s survival. The chief source of nonlinearity arises from the optimal formulation with the metabolic state determined by a convex combination of reactions contributing to the objective function. The model for anaerobic growth of E. coli was previously examined for multiple steady states in a chemostat fed by a mixture of glucose and pyruvate substrates under very specific conditions and experimentally verified. In this article, we explore the foregoing model for nonlinear behavior over the full range of parameters, γ (the fractional concentration of glucose in the feed mixture and D (the dilution rate. The observed multiplicity is in the cybernetic variables combining elementary modes. The results show steady-state multiplicity up to seven. No Hopf bifurcation was encountered, however. Bifurcation analysis of cybernetic models is complicated by the non-differentiability of the cybernetic variables for enzyme activities. A methodology is adopted here to overcome this problem, which is applicable to more complicated metabolic networks.

  17. Asymptotic Behavior of Equilibrium Point for a Class of Nonlinear Difference Equation

    Directory of Open Access Journals (Sweden)

    Gong Fei

    2009-01-01

    Full Text Available We study the asymptotic behavior of the solutions for the following nonlinear difference equation where the initial conditions are arbitrary nonnegative real numbers, are nonnegative integers, , and are positive constants. Moreover, some numerical simulations to the equation are given to illustrate our results.

  18. Asymptotic Behavior of Global Solution for Nonlinear Generalized Euler-Possion-Darboux Equation

    Institute of Scientific and Technical Information of China (English)

    LIANGBao-song; CHENZhen

    2004-01-01

    J. L Lions and W. A. Stranss [1] have proved the existence of a global solution of the initial boundary value problem for nonlinear generalized Euler-Possion-Darboux equation. In this paper we are going to investigate the asymptotic behavior of the global solution by a difference inequality.

  19. Oscillatory and Asymptotic Behavior of Solutions for Nonlinear Impulsive Delay Differential Equations

    Institute of Scientific and Technical Information of China (English)

    Wei-hua Mao; An-hua Wan

    2006-01-01

    The oscillatory and asymptotic behavior of the solutions for third order nonlinear impulsive delay differential equations are investigated. Some novel criteria for all solutions to be oscillatory or be asymptotic are established. Three illustrative examples are proposed to demonstrate the effectiveness of the conditions.

  20. Modeling the nonlinear PMMA behavior near glass transition temperature: application to its thermoforming

    Science.gov (United States)

    Gilormini, P.; Chevalier, L.; Régnier, G.

    2011-01-01

    Using suitable constitutive equations, numerical simulation allows predicting the properties of transparencies that are thermoformed near their glass transition temperature. Such equations are presented, which describe the nonlinear viscoelastic behavior of poly(methyl methacrylate) at large deformations near glass transition. The simulation of the thermoforming of a transparency at constant and uniform temperature is performed and compared with experimental results.

  1. Effect of carbonation on the linear and nonlinear dynamic properties of cement-based materials

    Science.gov (United States)

    Eiras, Jesus N.; Kundu, Tribikram; Popovics, John S.; Monzó, José; Borrachero, María V.; Payá, Jordi

    2016-01-01

    Carbonation causes a physicochemical alteration of cement-based materials, leading to a decrease of porosity and an increase of material hardness and strength. However, carbonation will decrease the pH of the internal pore water solution, which may depassivate the internal reinforcing steel, giving rise to structural durability concerns. Therefore, the proper selection of materials informed by parameters sensitive to the carbonation process is crucial to ensure the durability of concrete structures. The authors investigate the feasibility of using linear and nonlinear dynamic vibration response data to monitor the progression of the carbonation process in cement-based materials. Mortar samples with dimensions of 40×40×160 mm were subjected to an accelerated carbonation process through a carbonation chamber with 55% relative humidity and >95% of CO2 atmosphere. The progress of carbonation in the material was monitored using data obtained with the test setup of the standard resonant frequency test (ASTM C215-14), from a pristine state until an almost fully carbonated state. Linear dynamic modulus, quality factor, and a material nonlinear response, evaluated through the upward resonant frequency shift during the signal ring-down, were investigated. The compressive strength and the depth of carbonation were also measured. Carbonation resulted in a modest increase in the dynamic modulus, but a substantive increase in the quality factor (inverse attenuation) and a decrease in the material nonlinearity parameter. The combined measurement of the vibration quality factor and nonlinear parameter shows potential as a sensitive measure of material changes brought about by carbonation.

  2. Porosity-dependent nonlinear forced vibration analysis of functionally graded piezoelectric smart material plates

    Science.gov (United States)

    Qing Wang, Yan; Zu, Jean W.

    2017-10-01

    This work investigates the porosity-dependent nonlinear forced vibrations of functionally graded piezoelectric material (FGPM) plates by using both analytical and numerical methods. The FGPM plates contain porosities owing to the technical issues during the preparation of FGPMs. Two types of porosity distribution, namely, even and uneven distribution, are considered. A modified power law model is adopted to describe the material properties of the porous FGPM plates. Using D’Alembert’s principle, the out-of-plane equation of motion is derived by taking into account the Kármán nonlinear geometrical relations. After that, the Galerkin method is used to discretize the equation of motion, resulting in a set of ordinary differential equations with respect to time. These ordinary differential equations are solved analytically by employing the harmonic balance method. The approximate analytical results are verified by using the adaptive step-size fourth-order Runge–Kutta method. By means of the perturbation technique, the stability of approximate analytical solutions is examined. An interesting nonlinear broadband vibration phenomenon is detected in the FGPM plates with porosities. Nonlinear frequency-response characteristics of the present smart structures are investigated for various system parameters including the porosity type, the porosity volume fraction, the electric potential, the external excitation, the damping and the constituent volume fraction. It is found that these parameters have significant effects on the nonlinear vibration characteristics of porous FGPM plates.

  3. Effects of graphene quantum dots on linear and nonlinear optical behavior of malignant ovarian cells

    Science.gov (United States)

    Mohajer, Salman; Ara, Mohammad Hossein Majles; Serahatjoo, Leila

    2016-07-01

    We investigate linear and nonlinear optical properties of standard human ovarian cancer cells (cell line: A2780cp) in vitro. Cells were treated by graphene quantum dots (GQDs) with two special concentrations. Nontoxicity of GQDs was examined in standard biological viability tests. Cancerous cells were fixed on a glass slide; then, interaction of light with biofilms was studied in linear and nonlinear regimes. Absorption spectra of untreated biofilms and biofilms with two different concentrations of GQDs was studied by UV-visible spectrophotometer. Optical behavior of biofilms in a linear regime of intensity (with low-intensity laser exposure) was reported using a simple optical setup. After that, we compared the attenuation of light in biofilm of cancerous cells with and without GQDs. Nonlinear behavior of these biofilms was investigated by a Z-scan setup using a continued wave He-Ne laser. Results showed that GQDs decreased the extinction coefficient and changed the sign and exact value of the nonlinear refractive index of malignant ovarian cells noticeably. The nonlinear refractive index of studied cells with no GQDs treatment was in the order of 10-8 (cm2/w) with a positive sign. This quantity changed to the same order of magnitude with a negative sign after GQDs treatment. Thus, GQDs can be used for cancer diagnosis under laser irradiation.

  4. Study of nonlinear behaviors and modal reductions for friction destabilized systems. Application to an elastic layer

    Science.gov (United States)

    Loyer, A.; Sinou, J.-J.; Chiello, O.; Lorang, X.

    2012-02-01

    As noise reduction tends to be part of environmental directives, predicting squeal noise generated by disc brakes is an important industrial issue. It involves both the transient and stationary nonlinear dynamics of self-excited systems with frictional contact. Time simulation of the phenomenon is an attractive option for reducing experiment costs. However, since such computations using full finite element models of industrial disc brake systems is time-consuming, model reduction has to be performed. In this paper, both the transient and stationary nonlinear behaviors of the friction destabilized system and the effect of dynamical reduction on the nonlinear response of a simple friction destabilized system are carried out. The first part provides a description of the general modeling retained for friction destabilized systems. Then, discretization and solving processes for the stability analysis and the temporal evolution are presented. The third part presents an analysis of a sliding elastic layer for different operating conditions, in order to better understand the nonlinear behavior of such systems. Finally, spatial model reduction is performed with different kinds of reduction bases in order to analyze the different effects of modal reductions. This clearly shows the necessity of including static modes in the reduction basis and that nonlinear interactions between unstable modes are very difficult to represent with reduced bases. Finally, the proposed model and the associated studies are intended to be the benchmark cases for future comparison.

  5. Self-consistent photonic band structure of dielectric superlattices containing nonlinear optical materials.

    Science.gov (United States)

    Lousse, V; Vigneron, J P

    2001-02-01

    The theory of photonic crystals is extended to include the optical Kerr effect taking place in weak third-order, nonlinear materials present in the unit cell. The influence on the dispersion relations of the illumination caused by a single Bloch mode transiting through the crystal structure is examined. Special attention is given to the modification of the photonic gap width and position. Assuming an instantaneous change of refractive index with illumination, the nonlinear band structure problem is solved as a sequence of ordinary, linear band structure calculations, carried out in a plane-wave field representation.

  6. Crystal growth and comparison of vibrational and thermal properties of semi-organic nonlinear optical materials

    Indian Academy of Sciences (India)

    S Gunasekaran; G Anand; R Arun Balaji; J Dhanalakshmi; S Kumaresan

    2010-10-01

    Single crystals of urea thiourea mercuric sulphate (UTHS) and urea thiourea mercuric chloride (UTHC), semi-organic nonlinear optical materials, were grown by low-temperature solution growth technique by slow evaporation method using water as the solvent. Good quality single crystals were grown within three weeks. The nonlinear nature of the crystals was confirmed by SHG test. The UV–Vis spectrum showed the transmitting ability of the crystals in the entire visible region. FTIR spectrum was recorded and vibrational assignments were made. The degree of dopant inclusion was ascertained by AAS. The TGA–DTA studies showed the thermal properties of the crystals.

  7. Multilevel adaptive solution procedure for material nonlinear problems in visual programming environment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D.; Ghanem, R. [State Univ. of New York, Buffalo, NY (United States)

    1994-12-31

    Multigrid solution technique to solve a material nonlinear problem in a visual programming environment using the finite element method is discussed. The nonlinear equation of equilibrium is linearized to incremental form using Newton-Rapson technique, then multigrid solution technique is used to solve linear equations at each Newton-Rapson step. In the process, adaptive mesh refinement, which is based on the bisection of a pair of triangles, is used to form grid hierarchy for multigrid iteration. The solution process is implemented in a visual programming environment with distributed computing capability, which enables more intuitive understanding of solution process, and more effective use of resources.

  8. Geometrically Nonlinear Static Analysis of Edge Cracked Timoshenko Beams Composed of Functionally Graded Material

    Directory of Open Access Journals (Sweden)

    Şeref Doğuşcan Akbaş

    2013-01-01

    Full Text Available Geometrically nonlinear static analysis of edge cracked cantilever Timoshenko beams composed of functionally graded material (FGM subjected to a nonfollower transversal point load at the free end of the beam is studied with large displacements and large rotations. Material properties of the beam change in the height direction according to exponential distributions. The cracked beam is modeled as an assembly of two subbeams connected through a massless elastic rotational spring. In the study, the finite element of the beam is constructed by using the total Lagrangian Timoshenko beam element approximation. The nonlinear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. The convergence study is performed for various numbers of finite elements. In the study, the effects of the location of crack, the depth of the crack, and various material distributions on the nonlinear static response of the FGM beam are investigated in detail. Also, the difference between the geometrically linear and nonlinear analysis of edge cracked FGM beam is investigated in detail.

  9. A general one-dimension nonlinear magneto-elastic coupled constitutive model for magnetostrictive materials

    Directory of Open Access Journals (Sweden)

    Da-Guang Zhang

    2015-10-01

    Full Text Available For magnetostrictive rods under combined axial pre-stress and magnetic field, a general one-dimension nonlinear magneto-elastic coupled constitutive model was built in this paper. First, the elastic Gibbs free energy was expanded into polynomial, and the relationship between stress and strain and the relationship between magnetization and magnetic field with the polynomial form were obtained with the help of thermodynamic relations. Then according to microscopic magneto-elastic coupling mechanism and some physical facts of magnetostrictive materials, a nonlinear magneto-elastic constitutive with concise form was obtained when the relations of nonlinear strain and magnetization in the polynomial constitutive were instead with transcendental functions. The comparisons between the prediction and the experimental data of different magnetostrictive materials, such as Terfenol-D, Metglas and Ni showed that the predicted magnetostrictive strain and magnetization curves were consistent with experimental results under different pre-stresses whether in the region of low and moderate field or high field. Moreover, the model can fully reflect the nonlinear magneto-mechanical coupling characteristics between magnetic, magnetostriction and elasticity, and it can effectively predict the changes of material parameters with pre-stress and bias field, which is useful in practical applications.

  10. A general one-dimension nonlinear magneto-elastic coupled constitutive model for magnetostrictive materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Da-Guang; Li, Meng-Han; Zhou, Hao-Miao, E-mail: zhouhm@cjlu.edu.cn [College of Information Engineering, China Jiliang University, 310018, Hangzhou (China)

    2015-10-15

    For magnetostrictive rods under combined axial pre-stress and magnetic field, a general one-dimension nonlinear magneto-elastic coupled constitutive model was built in this paper. First, the elastic Gibbs free energy was expanded into polynomial, and the relationship between stress and strain and the relationship between magnetization and magnetic field with the polynomial form were obtained with the help of thermodynamic relations. Then according to microscopic magneto-elastic coupling mechanism and some physical facts of magnetostrictive materials, a nonlinear magneto-elastic constitutive with concise form was obtained when the relations of nonlinear strain and magnetization in the polynomial constitutive were instead with transcendental functions. The comparisons between the prediction and the experimental data of different magnetostrictive materials, such as Terfenol-D, Metglas and Ni showed that the predicted magnetostrictive strain and magnetization curves were consistent with experimental results under different pre-stresses whether in the region of low and moderate field or high field. Moreover, the model can fully reflect the nonlinear magneto-mechanical coupling characteristics between magnetic, magnetostriction and elasticity, and it can effectively predict the changes of material parameters with pre-stress and bias field, which is useful in practical applications.

  11. Dynamical Behavior of Nonlinear Viscoelastic Timoshenko Beams with Damage on a Viscoelastic Foundation%粘弹性地基上损伤粘弹性Timoshenko梁的非线性动力学行为

    Institute of Scientific and Technical Information of China (English)

    盛冬发; 张燕; 程昌钧

    2004-01-01

    Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams with large deflections, the nonlinear equations governing dynamical behavior of Timoshenko beams with damage on viscoelastic foundation were firstly derived. By using the Galerkin method in spatial domain, the nonlinear integro-partial differential equations were transformed into a set of integro-ordinary differential equations. The numerical methods in nonlinear dynamical systems, such as the phase-trajectory diagram, Poincare section and bifurcation figure, were used to solve the simplified systems of equations. It could be seen that simplified dynamical systems possess the plenty of nonlinear dynamical properties. The influence of load and material parameters on the dynamic behavior of nonlinear system were investigated in detail.

  12. A stable numerical solution method in-plane loading of nonlinear viscoelastic laminated orthotropic materials

    Science.gov (United States)

    Gramoll, K. C.; Dillard, D. A.; Brinson, H. F.

    1989-01-01

    In response to the tremendous growth in the development of advanced materials, such as fiber-reinforced plastic (FRP) composite materials, a new numerical method is developed to analyze and predict the time-dependent properties of these materials. Basic concepts in viscoelasticity, laminated composites, and previous viscoelastic numerical methods are presented. A stable numerical method, called the nonlinear differential equation method (NDEM), is developed to calculate the in-plane stresses and strains over any time period for a general laminate constructed from nonlinear viscoelastic orthotropic plies. The method is implemented in an in-plane stress analysis computer program, called VCAP, to demonstrate its usefulness and to verify its accuracy. A number of actual experimental test results performed on Kevlar/epoxy composite laminates are compared to predictions calculated from the numerical method.

  13. Metal-organic frameworks as competitive materials for non-linear optics.

    Science.gov (United States)

    Mingabudinova, L R; Vinogradov, V V; Milichko, V A; Hey-Hawkins, E; Vinogradov, A V

    2016-09-26

    The last five years have witnessed a huge breakthrough in the creation and the study of the properties of a new class of compounds - metamaterials. The next stage of this technological revolution will be the development of active, controllable, and non-linear metamaterials, surpassing natural media as platforms for optical data processing and quantum information applications. However, scientists are constantly faced with the need to find new methods that can ensure the formation of quantum and non-linear metamaterials with higher resolution. One such method of producing metamaterials in the future, which will provide scalability and availability, is chemical synthesis. Meanwhile, the chemical synthesis of organized 3D structures with a period of a few nanometers and a size of up to a few millimeters is not an easy task and is yet to be resolved. The most promising avenue seems to be the use of highly porous structures based on metal-organic frameworks that have demonstrated their unique properties in the field of non-linear optics (NLO) over the past three years. Thus, the aim of this review is to examine current progress and the possibilities of using metal-organic frameworks in the field of non-linear optics as chemically obtained metamaterials of the future. The review begins by presenting the theoretical principles of physical phenomena represented by mathematical descriptions for clarity. Major attention is paid to the second harmonic generation (SHG) effect. In this section we compare inorganic single crystals, which are most commonly used to study the effect in question, to organic materials, which also possess the required properties. Based on these data, we present a rationale for the possibility of studying the non-linear optical properties of metal-organic structures as well as describing the use of synthetic approaches and the difficulties associated with them. The second part of the review explicitly acquaints the reader with a new class of materials

  14. Nonlinear Dynamic Behaviors of Rotated Blades with Small Breathing Cracks Based on Vibration Power Flow Analysis

    Directory of Open Access Journals (Sweden)

    Hailong Xu

    2016-01-01

    Full Text Available Rotated blades are key mechanical components in turbomachinery and high cycle fatigues often induce blade cracks. Accurate detection of small cracks in rotated blades is very significant for safety, reliability, and availability. In nature, a breathing crack model is fit for a small crack in a rotated blade rather than other models. However, traditional vibration displacements-based methods are less sensitive to nonlinear characteristics due to small breathing cracks. In order to solve this problem, vibration power flow analysis (VPFA is proposed to analyze nonlinear dynamic behaviors of rotated blades with small breathing cracks in this paper. Firstly, local flexibility due to a crack is derived and then time-varying dynamic model of the rotated blade with a small breathing crack is built. Based on it, the corresponding vibration power flow model is presented. Finally, VPFA-based numerical simulations are done to validate nonlinear behaviors of the cracked blade. The results demonstrate that nonlinear behaviors of a crack can be enhanced by power flow analysis and VPFA is more sensitive to a small breathing crack than displacements-based vibration analysis. Bifurcations will occur due to breathing cracks and subharmonic resonance factors can be defined to identify breathing cracks. Thus the proposed method can provide a promising way for detecting and predicting small breathing cracks in rotated blades.

  15. Nonlinear Dynamics Behaviors of a Rotor Roller Bearing System with Radial Clearances and Waviness Considered

    Institute of Scientific and Technical Information of China (English)

    Wang Liqin; Cui Li; Zheng Dezhi; Gu Le

    2008-01-01

    A rotor system supported by roller bearings displays very complicated nonlinear behaviors due to nonlinear Hertzian contact forces, radial clearances and bearing waviness. This paper presents nonlinear bearing forces of a roller bearing under four-dimensional loads and establishes 4-DOF dynamics equations of a rotor roller bearing system. The methods of Newmark-β and of Newton-Laphson are used to solve the nonlinear equations. The dynamics behaviors of a rigid rotor system are studied through the bifurcation, the Poincar bility caused by the quasi-periodic bifurcation, the periodic-doubling bifurcation and chaos routes as the rotational speed increases.Clearances, outer race waviness, inner race waviness, roller waviness, damping, radial forces and unbalanced forces-all these bring a significant influence to bear on the system stability. As the clearance increases, the dynamics behaviors become complicated with the number and the scale of instable regions becoming larger. The vibration frequencies induced by the roller bearing waviness and the orders of the waviness might cause severe vibrations. The system is able to eliminate non-periodic vibration by reasonable choice and optimization of the parameters.

  16. Stability of Gain Scheduling Control for Aircraft with Highly Nonlinear Behavior

    Directory of Open Access Journals (Sweden)

    Fany Mendez-Vergara

    2014-01-01

    Full Text Available The main goal of this work is to study the stability properties of an aircraft with nonlinear behavior, controlled using a gain scheduled approach. An output feedback is proposed which is able to guarantee asymptotical stability of the task-coordinates origin and safety of the operation in the entire flight envelope. The results are derived using theory of hybrid and singular perturbed systems. It is demonstrated that both body velocity and orientation asymptotic tracking can be obtained in spite of nonlinearities and uncertainty. The results are illustrated using numerical simulations in F16 jet.

  17. STABILITY AND BIFURCATION BEHAVIORS ANALYSIS IN A NONLINEAR HARMFUL ALGAL DYNAMICAL MODEL

    Institute of Scientific and Technical Information of China (English)

    WANG Hong-li; FENG Jian-feng; SHEN Fei; SUN Jing

    2005-01-01

    A food chain made up of two typical algae and a zooplankton was considered. Based on ecological eutrophication, interaction of the algal and the prey of the zooplankton, a nutrient nonlinear dynamic system was constructed. Using the methods of the modern nonlinear dynamics, the bifurcation behaviors and stability of the model equations by changing the control parameter r were discussed. The value of r for bifurcation point was calculated, and the stability of the limit cycle was also discussed. The result shows that through quasi-periodicity bifurcation the system is lost in chaos.

  18. Nonlinear response of plain concrete shear walls with elastic-damaging behavior

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, S.; Schreyer, H.L.

    1997-02-01

    This report summarizes the theoretical and computational efforts on the modeling of small scale shear walls. Small scale shear walls are used extensively in the study of shear wall behavior because the construction and testing of full size walls are rather expensive. A finite element code is developed which incorporates nonlinear constitutive relations of damage mechanics. The program is used to obtain nonlinear load-deformation curves and to address the initial loss of stiffness due to shrinkage cracking. The program can also be used to monitor the continuous degradation of the fundamental frequency due to progressive damage.

  19. A molecular mechanics approach for analyzing tensile nonlinear deformation behavior of single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Yu Wang; Daining Fang; Ai Kah Soh; Bin Liu

    2007-01-01

    In this paper, by capturing the atomic informa-tion and reflecting the behaviour governed by the nonlin-ear potential function, an analytical molecular mechanics approach is proposed. A constitutive relation for single-walled carbon nanotubes (SWCNT's) is established to describe the nonlinear stress-strain curve of SWCNT's and to predict both the elastic properties and breaking strain of SWCNT's during tensile deformation. An analysis based on the virtual internal bond (VIB) model proposed by P. Zhang et al. is also presented for comparison. The results indicate that the proposed molecular mechanics approach is indeed an acceptable analytical method for analyzing the mechanical behavior of SWCNT's.

  20. Time-Dependent Nonlinear Optical Susceptibility of an Out-of-Equilibrium Soft Material

    Science.gov (United States)

    Ghofraniha, Neda; Conti, Claudio; Ruocco, Giancarlo; Zamponi, Francesco

    2009-01-01

    We investigate the time-dependent nonlinear optical absorption of a clay dispersion (Laponite) in an organic dye (rhodamine B) water solution displaying liquid-arrested state transition. Specifically, we determine the characteristic time τD of the nonlinear susceptibility buildup due to the Soret effect. By comparing τD with the relaxation time provided by standard dynamic light scattering measurements we report on the decoupling of the two collective diffusion times at the two very different length scales during the aging of the out-of-equilibrium system. With this demonstration experiment we also show the potentiality of nonlinear optics measurements in the study of the late stage of arrest in soft materials.

  1. Nonlinear shear behavior of rock joints using a linearized implementation of the Barton–Bandis model

    Directory of Open Access Journals (Sweden)

    Simon Heru Prassetyo

    2017-08-01

    Full Text Available Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing, inducing dilation and resulting in nonlinear joint shear strength and shear stress vs. shear displacement behaviors. The Barton–Bandis (BB joint model provides the most realistic prediction for the nonlinear shear behavior of rock joints. The BB model accounts for asperity roughness and strength through the joint roughness coefficient (JRC and joint wall compressive strength (JCS parameters. Nevertheless, many computer codes for rock engineering analysis still use the constant shear strength parameters from the linear Mohr–Coulomb (M−C model, which is only appropriate for smooth and non-dilatant joints. This limitation prevents fractured rock models from capturing the nonlinearity of joint shear behavior. To bridge the BB and the M−C models, this paper aims to provide a linearized implementation of the BB model using a tangential technique to obtain the equivalent M−C parameters that can satisfy the nonlinear shear behavior of rock joints. These equivalent parameters, namely the equivalent peak cohesion, friction angle, and dilation angle, are then converted into their mobilized forms to account for the mobilization and degradation of JRC under shearing. The conversion is done by expressing JRC in the equivalent peak parameters as functions of joint shear displacement using proposed hyperbolic and logarithmic functions at the pre- and post-peak regions of shear displacement, respectively. Likewise, the pre- and post-peak joint shear stiffnesses are derived so that a complete shear stress-shear displacement relationship can be established. Verifications of the linearized implementation of the BB model show that the shear stress-shear displacement curves, the dilation behavior, and the shear strength envelopes of rock joints are consistent with available experimental and numerical results.

  2. Modeling of nonlinear optic and ESR response of CDW MX materials

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, A.; Gammel, J.T.; Bishop, A.R. [Los Alamos National Lab., NM (United States); Shuai, Z.; Bredas, J.L. [Center de Recherche en Electronique et Photonique Moleculaires, Universite de Mons-Hainaut (Belgium); Batistic, I. [Zagreb Univ. (Croatia). Dept. of Physics; Alouani, M. [Ohio State Univ., Columbus, OH (United States). Dept. of Physics

    1994-09-01

    We report results on the nonlinear optic and ESR response of the PtX MX chain materials calculated using a discrete, 3/4-filled, two-band, tight-binding Peierls-Hubbard model. We calculated electroabsorption (EA) spectra for the three PtX (X=Cl, Br, 1) charge-density-wave (CDW) materials and find good agreement with the experimental data. We also obtain EA spectra for localized defects in PtBr. In addition, the field orientation dependence of the electron spin resonance spectra associated with the spin carrying defects is calculated for PtX materials and compared with ESR data on photoinduced defects.

  3. Non-linear model of impurity diffusion in nanoporous materials upon ultrasonic treatment

    Directory of Open Access Journals (Sweden)

    R.M. Peleshchak

    2014-06-01

    Full Text Available Non-linear theory of diffusion of impurities in porous materials upon ultrasonic treatment is described. It is shown that at a defined value of deformation amplitude, an average concentration of vacancies and temperature as a result of the effect of ultrasound possibly leads to the formation of nanoclusters of vacancies and to their periodic educations in porous materials. It is shown that at a temperature smaller than some critical value, a significant growth of a diffusion coefficient is observed in porous materials.

  4. Nonlinear threshold behavior during the loss of Arctic sea ice

    CERN Document Server

    Eisenman, I; 10.1073/pnas.0806887106

    2008-01-01

    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or "tipping point") beyond which the ice-albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice-albedo feedback. Here we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that while the ice-albedo feedback promotes the existence of multiple ice cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice-covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a ...

  5. Nonlinear threshold behavior during the loss of Arctic sea ice.

    Science.gov (United States)

    Eisenman, I; Wettlaufer, J S

    2009-01-06

    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or "tipping point") beyond which the ice-albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice-albedo feedback. Here, we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that although the ice-albedo feedback promotes the existence of multiple ice-cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea-ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a critical threshold associated with the sudden loss of the remaining wintertime-only sea ice cover may be likely.

  6. Nonlinear light behaviors near phase transition in non-parity-time-symmetric complex waveguides

    CERN Document Server

    Nixon, Sean

    2016-01-01

    Many classes of non-parity-time (PT) symmetric waveguides with arbitrary gain and loss distributions still possess all-real linear spectrum or exhibit phase transition. In this article, nonlinear light behaviors in these complex waveguides are probed analytically near a phase transition. Using multi-scale perturbation methods, a nonlinear ordinary differential equation (ODE) is derived for the light's amplitude evolution. This ODE predicts that the first class of these non-PT-symmetric waveguides support continuous families of solitons and robust amplitude-oscillating solutions both above and below phase transition, in close analogy with PT-symmetric systems. For the other classes of waveguides, the light's intensity always amplifies under the effect of nonlinearity even if the waveguide is below phase transition. These analytical predictions are confirmed by direct computations of the full system.

  7. Nonlinear Optical Properties of Organic and Polymeric Thin Film Materials of Potential for Microgravity Processing Studies

    Science.gov (United States)

    Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.; Penn, Benjamin; Witherow, William K.; Bank, Curtis; Shields, Angela; Hicks, Rosline; Ashley, Paul R.

    1996-01-01

    In this paper, we will take a closer look at the state of the art of polydiacetylene, and metal-free phthalocyanine films, in view of the microgravity impact on their optical properties, their nonlinear optical properties and their potential advantages for integrated optics. These materials have many attractive features with regard to their use in integrated optical circuits and optical switching. Thin films of these materials processed in microgravity environment show enhanced optical quality and better molecular alignment than those processed in unit gravity. Our studies of these materials indicate that microgravity can play a major role in integrated optics technology. Polydiacetylene films are produced by UV irradiation of monomer solution through an optical window. This novel technique of forming polydiacetylene thin films has been modified for constructing sophisticated micro-structure integrated optical patterns using a pre-programmed UV-Laser beam. Wave guiding through these thin films by the prism coupler technique has been demonstrated. The third order nonlinear parameters of these films have been evaluated. Metal-free phthalocyanine films of good optical quality are processed in our laboratories by vapor deposition technique. Initial studies on these films indicate that they have excellent chemical, laser, and environmental stability. They have large nonlinear optical parameters and show intrinsic optical bistability. This bistability is essential for optical logic gates and optical switching applications. Waveguiding and device making investigations of these materials are underway.

  8. An experimental study on stress-strain behavior and constitutive model of hardfill material

    Science.gov (United States)

    Wu, Mengxi; Du, Bin; Yao, Yuancheng; He, Xianfeng

    2011-11-01

    Hardfill is a new type of artificially cemented material for dam construction works, with a wide application prospect. Its mechanical behavior lies between concrete and rockfill materials. A series of large-scale triaxial tests are performed on hardfill specimens at different ages, and the stress-strain behavior of hardfill is further discussed. The strength and stress-strain relationship of hardfill materials show both frictional mechanism and cohesive mechanism. An age-related constitutive model of hardfill is developed, which is a parallel model consisting of two components, rockfill component and cementation component. Moreover, a comparison is made between the simulated and the experimental results, which shows that the parallel model can reflect the mechanical characteristics of both rockfill-like nonlinearity and concrete-like age relativity. In addition, a simplified method for the determination of parameters is proposed.

  9. Nonlinear elastic behavior of rocks revealed by dynamic acousto-elastic testing

    Science.gov (United States)

    Shokouhi, Parisa; Riviere, Jacques; Guyer, Robert; Johnson, Paul

    2017-04-01

    Nonlinear elastic behavior of rocks is studied at the laboratory scale with the goal of illuminating observations at the Earth scale, for instance during strong ground motion and earthquake slip processes. A technique called Dynamic Acousto-Elastic Testing (DAET) is used to extract the nonlinear elastic response of disparate rocks (sandstone, granite and soapstone). DAET is the dynamic analogous to standard (quasi-static) acousto-elastic testing. It consists in measuring speed of sound with high-frequency low amplitude pulses (MHz range) across the sample while it is dynamically loaded with a low frequency, large amplitude resonance (kHz range). This particular configuration provides the instantaneous elastic response over a full dynamic cycle and reveals unprecedented details: instantaneous softening, tension/compression asymmetry as well as hysteretic behaviors. The strain-induced modulation of ultrasonic pulse velocities ('fast dynamics') is analyzed to extract nonlinearity parameters. A projection method is used to extract the harmonic content and a careful comparison of the fast dynamics response is made. In order to characterize the rate of elastic recovery ('slow dynamics'), we continue to monitor the ultrasonic wave velocity for about 30 minutes after the low-frequency resonance is turned off. In addition, the frequency, pressure and humidity dependences of the nonlinear parameters are reported for a subset of samples. We find that the nonlinear components can be clustered into two categories, which suggests that two main mechanisms are at play. The first one, related to the second harmonic, is likely related to the opening/closing of microstructural features such as cracks and grain/grain contacts. In contrast, the second mechanism is related to all other nonlinear parameters (transient softening, hysteresis area and higher order harmonics) and may arise from shearing mechanisms at grain interfaces.

  10. Modeling Granular Materials as Compressible Non-Linear Fluids: Heat Transfer Boundary Value Problems

    Energy Technology Data Exchange (ETDEWEB)

    Massoudi, M.C.; Tran, P.X.

    2006-01-01

    We discuss three boundary value problems in the flow and heat transfer analysis in flowing granular materials: (i) the flow down an inclined plane with radiation effects at the free surface; (ii) the natural convection flow between two heated vertical walls; (iii) the shearing motion between two horizontal flat plates with heat conduction. It is assumed that the material behaves like a continuum, similar to a compressible nonlinear fluid where the effects of density gradients are incorporated in the stress tensor. For a fully developed flow the equations are simplified to a system of three nonlinear ordinary differential equations. The equations are made dimensionless and a parametric study is performed where the effects of various dimensionless numbers representing the effects of heat conduction, viscous dissipation, radiation, and so forth are presented.

  11. The effect of large deformation and material nonlinearity on gel indentation

    Institute of Scientific and Technical Information of China (English)

    Zheng Duan; Yonghao An; Jiaping Zhang; Hanqing Jiang

    2012-01-01

    A gel,an aggregate of polymers with solvents,has dual attributes of solid and liquid as solvent migrates in and out of the polymer network.Indentation has recently been used to characterize the mechanical properties of gels.This paper evaluates the effects of large deformation and material nonlinearity on gel indentation through theoretical modeling and finite element analysis.It is found that large deformation significantly affects the interpretation of the experimental observations and the classical relation between indentation force and depth has limitations for large deformation.The material nonlinearity does not play a very important role on indentation experiment so that the poroelasticity is a good approximation.Based on these observations,this paper proposes an alternative approach to measure the mechanical properties of gels,namely,uniaxial compression experiment.

  12. (3+1)-dimensional nonlinear propagation equation for ultrashort pulsed beam in left-handed material

    Institute of Scientific and Technical Information of China (English)

    Hu Yong-Hua; Fu Xi-Quan; Wen Shuang-Chun; Su Wen-Hua; Fan Dian-Yuan

    2006-01-01

    In this paper a comprehensive framework for treating the nonlinear propagation of ultrashort pulse in metamaterial with dispersive dielectric susceptibility and magnetic permeability is presented. Under the slowly-evolving-wave approximation, a generalized (3+1)-dimensional wave equation first order in the propagation coordinate and suitable for both right-handed material (RHM) and left-handed material (LHM) is derived. By the commonly used Drude dispersive model for LHM, a (3+1)-dimensional nonlinear Schr(o)dinger equation describing ultrashort pulsed beam propagation in LHM is obtained, and its difference from that for conventional RHM is discussed. Particularly, the self-steeping effect of ultrashort pulse is found to be anomalous in LHM.

  13. Beyond the perturbative description of the nonlinear optical response of low-index materials.

    Science.gov (United States)

    Reshef, Orad; Giese, Enno; Zahirul Alam, M; De Leon, Israel; Upham, Jeremy; Boyd, Robert W

    2017-08-15

    We show that standard approximations in nonlinear optics are violated for situations involving a small value of the linear refractive index. Consequently, the conventional equation for the intensity-dependent refractive index, n(I)=n0+n2I, becomes inapplicable in epsilon-near-zero and low-index media, even in the presence of only third-order effects. For the particular case of indium tin oxide, we find that the χ((3)), χ((5)), and χ((7)) contributions to refraction eclipse the linear term; thus, the nonlinear response can no longer be interpreted as a perturbation in these materials. Although the response is non-perturbative, we find no evidence that the power series expansion of the material polarization diverges.

  14. Third-order nonlinear optical materials: practical issues and theoretical challenges.

    Science.gov (United States)

    Samoć, Marek

    2011-09-01

    The renewed interest in all-optical switching has led to more detailed experimental investigations of nonlinear optical properties of materials within wide wavelength ranges. The objectives of these studies are discussed here in the context of the availability of suitable computational data that might be compared with the results of the experimental research. It is concluded that the currently available data are insufficient and should be augmented to provide better guidance for experimental work.

  15. Understanding of Materials State and its Degradation using Non-Linear Ultrasound (NLU) Approaches

    Science.gov (United States)

    2011-07-01

    at Ultrasonic Frequencies, Journal of Applied Physics 105, 043520, Hikata A., Chick B. B., and Elbaum C., (1965) Dislocation Contribution to the...Second Harmonic Generation of ultrasonic waves, Journal of Applied Physics Vol. 36 Number1 Hikata A. and Elbaum C., (1966) Generation of...Material Damage in a Nickel-base Superalloy using Nonlinear Rayleigh Surface Waves, Journal of Applied Physics 99, 124913 Hurley D. C., Balzar D

  16. Implementation of tristate logic based all optical flip-flop with nonlinear material

    Institute of Scientific and Technical Information of China (English)

    Partha Ghosh; Sourangshu Mukhopadhyay

    2005-01-01

    @@ The advantages of multivalued logic in optical parallel computation need no introduction. There are lots of proposals, already reported, where tristate, quarternary state logic operations can be performed with optics. Here we report a new approach to implement tristate logic based all optical flip-flop using optical nonlinear material. The concept and the principle of operation of this type of flip-flop are different from that of the conventional binary one.

  17. Modeling and characterization of long term material behavior in polymer composites with woven fiber architecture

    Science.gov (United States)

    Gupta, Vikas

    The purpose of this research is to develop an analytical tool which, when coupled with accelerated material characterization, is capable of predicting long-term durability of polymers and their composites. Conducting creep test on each composite laminate with different fibers, fiber volume fractions, and weave architectures is impractical. Moreover, in case of thin laminates, accurately characterizing the out-of-plane matrix dominated viscoelastic response is not easily achievable. Therefore, the primary objective of this paper is to present a multi-scale modeling methodology to simulate the long-term interlaminar properties in polymer matrix woven composites and then predict the critical regions where failure is most likely to occur. A micromechanics approach towards modeling the out-of-plane viscoelastic behavior of a five-harness satin woven-fiber cross-ply composite laminate is presented, taking into consideration the weave architecture and time-dependent effects. Short-term creep tests were performed on neat resin at different test temperatures and stress levels to characterize physical aging of the resin matrix. In addition, creep and recovery experiments were conducted on un-aged resin specimens in order to characterize the pronounced stress-dependent nonlinear viscoelastic response of the PR500 resin. Two-dimensional micromechanics analysis was carried out using a test-bed finite element code, NOVA-3D, including interactions between non-linear material constitutive behavior, geometric nonlinearity, aging and environmental effects.

  18. A contribution to the development of wide band-gap nonlinear optical laser materials

    Science.gov (United States)

    Stone-Sundberg, Jennifer Leigh

    The primary focus of this work is on examining structure-property relationships of interest for high-power nonlinear optical and laser crystals. An intuitive and simply illustrated method for assessing the nonlinear optical potential of structurally characterized noncentrosymmetric materials is introduced. This method is applied to materials including common quartz and tourmaline and then extended to synthetic materials including borates, silicates, aluminates, and phosphates. Particularly, the contributions of symmetric tetrahedral and triangular anionic groups are inspected. It is shown that both types of groups significantly contribute to the optical frequency converting abilities of noncentrosymmetric crystals. In this study, several known materials are included as well as several new materials. The roles of the orientation, composition, and packing density of these anionic groups are also discussed. The structures and optical properties of the known materials BPO 4, NaAlO2, LaCa4O(BO3)3, and tourmaline; the new compounds La0.8Y0.2Sc3 (BO3)4 and Ba2B10O 17; and the laser host Sr3Y0.75Yb0.25(BO 3)3 are described.

  19. Homogenization of the transport behavior of nonlinearly adsorbing pollutants in physically and chemically heterogeneous aquifers

    Science.gov (United States)

    Attinger, Sabine; Dimitrova, Jiva; Kinzelbach, Wolfgang

    2009-05-01

    This paper addresses the question of how spatial variability in the hydraulic and chemical properties of groundwater systems affects the transport and sorption behavior of pollutants at the field scale. In this paper, we limit our investigations on pollutants that adsorb according to an equilibrium controlled nonlinear Freundlich sorption isotherm. The new contribution of this paper is take into account not only spatially variable Freundlich distribution coefficients KS but spatially variable Freundlich nonlinearity parameters p as well. Using a homogenization theory approach, we shortly review the impact of spatially variable hydraulic properties on the transport and extend the theory to spatially variable chemical properties. We show that spatially variable Freundlich exponents cause a very different field scale transport and sorption behavior than spatial variations in the distribution coefficients only since in the first case field scale Freundlich parameters and field scale dispersion coefficients become concentration dependent. In particular, field scale retardation is much larger than small-scale retardation.

  20. Cooperative enhancement of the nonlinear optical response in conjugated energetic materials: A TD-DFT study.

    Science.gov (United States)

    Sifain, Andrew E; Tadesse, Loza F; Bjorgaard, Josiah A; Chavez, David E; Prezhdo, Oleg V; Scharff, R Jason; Tretiak, Sergei

    2017-03-21

    Conjugated energetic molecules (CEMs) are a class of explosives with high nitrogen content that posses both enhanced safety and energetic performance properties and are ideal for direct optical initiation. As isolated molecules, they absorb within the range of conventional lasers. Crystalline CEMs are used in practice, however, and their properties can differ due to intermolecular interaction. Herein, time-dependent density functional theory was used to investigate one-photon absorption (OPA) and two-photon absorption (TPA) of monomers and dimers obtained from experimentally determined crystal structures of CEMs. OPA scales linearly with the number of chromophore units, while TPA scales nonlinearly, where a more than 3-fold enhancement in peak intensity, per chromophore unit, is calculated. Cooperative enhancement depends on electronic delocalization spanning both chromophore units. An increase in sensitivity to nonlinear laser initiation makes these materials suitable for practical use. This is the first study predicting a cooperative enhancement of the nonlinear optical response in energetic materials composed of relatively small molecules. The proposed model quantum chemistry is validated by comparison to crystal structure geometries and the optical absorption of these materials dissolved in solution.

  1. Metal-nanocluster composites made by ion implantation: A novel third-order nonlinear material

    Energy Technology Data Exchange (ETDEWEB)

    Haglund, R.F. Jr.; Yang, L.; Magruder, R.H. III; Becker, K.; Wittig, J.E. [Vanderbilt Univ., Nashville, TN (United States); White, C.W.; Zhur, R.A. [Oak Ridge National Lab., TN (United States); Yang, L.; Dorsinville, R.; Alfano, R.R. [City Univ. of New York, NY (United States)

    1993-03-01

    We describe our recent studies of metal-insulator nanocluster composites made by ion implantation in such substrates as glass and sapphire. The metal clusters have diameters ranging from 3 to 30 nm. The composites exhibit an electronic nonlinear optical response which is fast on the picosecond time scale. In addition to possibilities for technological application, these materials also offer a way of studying unusual properties of composite materials, such as the quantum confinement of conduction-band electrons and the transverse relaxation time T{sub 2} as a function of cluster size.

  2. Metal-nanocluster composites made by ion implantation: A novel third-order nonlinear material

    Energy Technology Data Exchange (ETDEWEB)

    Haglund, R.F. Jr.; Yang, L.; Magruder, R.H. III; Becker, K.; Wittig, J.E. (Vanderbilt Univ., Nashville, TN (United States)); White, C.W.; Zhur, R.A. (Oak Ridge National Lab., TN (United States)); Yang, L.; Dorsinville, R.; Alfano, R.R. (City Univ. of New York, NY (United States))

    1993-03-01

    We describe our recent studies of metal-insulator nanocluster composites made by ion implantation in such substrates as glass and sapphire. The metal clusters have diameters ranging from 3 to 30 nm. The composites exhibit an electronic nonlinear optical response which is fast on the picosecond time scale. In addition to possibilities for technological application, these materials also offer a way of studying unusual properties of composite materials, such as the quantum confinement of conduction-band electrons and the transverse relaxation time T[sub 2] as a function of cluster size.

  3. Nonminimum Phase Behavior of Laser Material Processing

    NARCIS (Netherlands)

    Römer, G.R.B.E.; Weerkamp, N.P.; Meijer, J.; Postma, S.

    2001-01-01

    Optical sensors are increasingly applied in laser material processing to monitor and control the lasermaterial interaction zone. Dynamic models, relating the sensor signals (e.g. as temperature or molten area) to the process inputs (e.g. laser power or beam velocity), provide the basis for the desig

  4. Micromechanical Behavior of Frictional Geologic Materials

    Science.gov (United States)

    1988-11-01

    ranging from a suspension of particles to multicontacted particles forming a material with continuous force-deformation characteristics, i.e., a...Vol. 14, No. 4, pp. 25-38 (1974). 15. Biarez, J., "Contribution a l’Etude des Proprietes Mecaniques des Sols et des Materiaux Pulverulents," These de

  5. Emerging Low-Dimensional Materials for Nonlinear Optics and Ultrafast Photonics.

    Science.gov (United States)

    Liu, Xiaofeng; Guo, Qiangbing; Qiu, Jianrong

    2017-02-22

    Low-dimensional (LD) materials demonstrate intriguing optical properties, which lead to applications in diverse fields, such as photonics, biomedicine and energy. Due to modulation of electronic structure by the reduced structural dimensionality, LD versions of metal, semiconductor and topological insulators (TIs) at the same time bear distinct nonlinear optical (NLO) properties as compared with their bulk counterparts. Their interaction with short pulse laser excitation exhibits a strong nonlinear character manifested by NLO absorption, giving rise to optical limiting or saturated absorption associated with excited state absorption and Pauli blocking in different materials. In particular, the saturable absorption of these emerging LD materials including two-dimensional semiconductors as well as colloidal TI nanoparticles has recently been utilized for Q-switching and mode-locking ultra-short pulse generation across the visible, near infrared and middle infrared wavelength regions. Beside the large operation bandwidth, these ultrafast photonics applications are especially benefit from the high recovery rate as well as the facile processibility of these LD materials. The prominent NLO response of these LD materials have also provided new avenues for the development of novel NLO and photonics devices for all-optical control as well as optical circuits beyond ultrafast lasers.

  6. Application of constitutive model considering nonlinear unloading behavior for Gen.3 AHSS

    Science.gov (United States)

    Sun, Li; Wagoner, R. H.

    2013-05-01

    Nonlinear unloading behavior has been reported as an important factor for accurate springback prediction. In this study, a newly proposed special component of strain: "Quasi-Plastic-Elastic" ("QPE") strain was utilized to study the springback behavior of Advanced High Strength Steels (AHSS). Several types of steels, including IF steel, DP780, TRIP780, DP980, TWIP980 and QP980 were considered in this research. The results showed that all the tested steels have following behavior: 1) QPE strain is recoverable, like elastic deformation. 2) It dissipates work, like plastic deformation. A 3-D constitutive model considering QPE behavior was implemented in Abaqus/Standard with shell element and applied to draw-bend springback test for Gen. 3 AHSS, QP980. Predictions for springback using the QPE model were more accurate compared with standard elastic-plastic models.

  7. Metal-organic frameworks for electronics: emerging second order nonlinear optical and dielectric materials.

    Science.gov (United States)

    Mendiratta, Shruti; Lee, Cheng-Hua; Usman, Muhammad; Lu, Kuang-Lieh

    2015-10-01

    Metal-organic frameworks (MOFs) have been intensively studied over the past decade because they represent a new category of hybrid inorganic-organic materials with extensive surface areas, ultrahigh porosity, along with the extraordinary tailorability of structure, shape and dimensions. In this highlight, we summarize the current state of MOF research and report on structure-property relationships for nonlinear optical (NLO) and dielectric applications. We focus on the design principles and structural elements needed to develop potential NLO and low dielectric (low-κ) MOFs with an emphasis on enhancing material performance. In addition, we highlight experimental evidence for the design of devices for low-dielectric applications. These results motivate us to develop better low-dielectric and NLO materials and to perform in-depth studies related to deposition techniques, patterning and the mechanical performance of these materials in the future.

  8. Dynamic High-Pressure Behavior of Hierarchical Heterogeneous Geological Materials

    Science.gov (United States)

    2016-04-01

    pressure -density Hugoniot plots for simulations using the ‘mix 5’ option, as will be presented later. The volume weighted option for mixed cells (refered...AFRL-AFOSR-VA-TR-2016-0150 Dynamic High- Pressure Behavior of Geological Materials Naresh Thadhani GEORGIA TECH RESEARCH CORPORATION Final Report 04...31-12-2015 4.  TITLE AND SUBTITLE Dynamic High- Pressure Behavior of Hierarchical Heterogeneous Geological Materials 5a.  CONTRACT NUMBER 5b.  GRANT

  9. Growth and characterization of dexterous nonlinear optical material: Dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol (DMAPNP)

    Science.gov (United States)

    Saravanan, M.

    2016-08-01

    The crystals (dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol [DMAPNP] suitable for NLO applications were grown by the slow cooling method. The solubility and metastable zone width measurement of DMAPNP specimen was studied. The material crystallizes in the orthorhombic crystal system with noncentrosymmetric space group of P212121. The ocular precision in the intact visible region was found to be good for non-linear optical claim. Quality of the grown crystal is ascertained by the HRXRD and etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of DMAPNP sample at different temperatures was investigated to determine the hardness stability of the grown specimen. The piezoelectric temperament and the relative Second Harmonic Generation (for diverse particle sizes) of the material were also studied. The third order nonlinear optical properties of DMAPNP crystals were premeditated by Z-scan method. Birefringence and optical homogeneity of the crystal were evaluated using modified channel spectrum method. The half wave voltage of the grown crystal deliberate from the elector optic experimentation. Photoconductivity measurement specified consummate of inducing dipoles owing to brawny incident radiation and also disclose the nonlinear activities of the grown specimen.

  10. Second harmonic generation of near millimeter wave radiation by nonlinear bulk material

    Science.gov (United States)

    Ahn, B. H.

    1980-06-01

    Bulk crystals have been used frequently to obtain second harmonic generation (SHG) and third harmonic generation (THG) of radiation from the fundamental input frequency, particularly in the optical region. For example ammonium dihydrogen phosphate, potassium dihydrogen phosphate, semiconductor materials, and ferroelectric materials were used for the SHG of input laser beams. SHG and THG have also been realized in the microwave region. Boyd, et. al., reported on the nonlinear coefficients and other important parameters at 55 GHz. Later, Boyd and Pollack published a comprehensive paper on the nonlinear coefficients of LiTaO3 and LiNbO3 in the microwave region. DiDomenico, Jrl, et. al., obtained a 9 GHz TH output with an efficiency of 8.5% from a 2200 watt 3 GHz source by use of a 73% BaTiO3 - 27% SrTiO3 ceramic in a coaxial cavity configuration. Impetus for bulk harmonic generation in the microwave region was given by the discovery that some ferroelectric crystals have very large nonlinear coefficients, large enough to compensate for the lower frequencies of the microwave region in comparison to those of the optical region.

  11. Sex Role Socialization Via Teachers' Behavior and Sexually Stereotyped Materials.

    Science.gov (United States)

    Snodgrass, Sara E.; And Others

    Research has shown that children's differentiation of gender-appropriate behavior is not directly affected by their teacher's gender. However, the teacher's behavior in relation to the material being taught may convey the sex-appropriateness or -inappropriateness to the child. To examine the effects of student gender and sexual stereotype of the…

  12. Fair Verbal Behavior: A Protocol Materials Unit for Teachers.

    Science.gov (United States)

    Mullis, Ina V. S.

    This protocol materials unit, based on the interaction component of instruction, is designed to help prospective teachers better understand verbal behaviors as related to fair (positive feedback) and unfair (negative feedback) responses. Fair verbal behavior is defined as following a standard of equal treatment toward all students and as free from…

  13. A computer program for predicting nonlinear uniaxial material responses using viscoplastic models

    Science.gov (United States)

    Chang, T. Y.; Thompson, R. L.

    1984-01-01

    A computer program was developed for predicting nonlinear uniaxial material responses using viscoplastic constitutive models. Four specific models, i.e., those due to Miller, Walker, Krieg-Swearengen-Rhode, and Robinson, are included. Any other unified model is easily implemented into the program in the form of subroutines. Analysis features include stress-strain cycling, creep response, stress relaxation, thermomechanical fatigue loop, or any combination of these responses. An outline is given on the theoretical background of uniaxial constitutive models, analysis procedure, and numerical integration methods for solving the nonlinear constitutive equations. In addition, a discussion on the computer program implementation is also given. Finally, seven numerical examples are included to demonstrate the versatility of the computer program developed.

  14. Three-dimensional Material and Geometrical Nonlinear Analysis of Adhesively Bonded Single Lap Joint

    Directory of Open Access Journals (Sweden)

    S. Narasimhan

    2003-04-01

    Full Text Available The paper presents 3-D viscoplastic analysis of adhesively bonded single lap joint considering material and geometric nonlinearity. Total Lagrangian formulation is used to develop a 3-D finite element for geometric nonlinear analysis. The overall geometry of the single lap joint, the loading, and the boundary conditions has been considered, both according to the ASTM testing standards and from those adopted in earlier investigations. The constitutive relations for the adhesive are developed using a pressure-dependant (modified von Mises yield function and Ramberg-Osgood idealisation for the experimental stress-strain curve. The adherends and adhesive layers are both modelled using 20-noded solid elements. However, observations have been made, in particular, on peel and shear stresses in the adhesive layer, which provide useful insight into the 3-D nature of the problem.

  15. A nonlinear manifold-based reduced order model for multiscale analysis of heterogeneous hyperelastic materials

    Science.gov (United States)

    Bhattacharjee, Satyaki; Matouš, Karel

    2016-05-01

    A new manifold-based reduced order model for nonlinear problems in multiscale modeling of heterogeneous hyperelastic materials is presented. The model relies on a global geometric framework for nonlinear dimensionality reduction (Isomap), and the macroscopic loading parameters are linked to the reduced space using a Neural Network. The proposed model provides both homogenization and localization of the multiscale solution in the context of computational homogenization. To construct the manifold, we perform a number of large three-dimensional simulations of a statistically representative unit cell using a parallel finite strain finite element solver. The manifold-based reduced order model is verified using common principles from the machine-learning community. Both homogenization and localization of the multiscale solution are demonstrated on a large three-dimensional example and the local microscopic fields as well as the homogenized macroscopic potential are obtained with acceptable engineering accuracy.

  16. Nonlinear constitutive law for ferroelectric/ ferroelastic material and its finite element realization

    Institute of Scientific and Technical Information of China (English)

    LI YaoChen

    2007-01-01

    The hysteresis phenomena of ferroelectric/ferroelastic material in polarization procedure are investigated.Some assumptions are presented based on the published experimental data.The electrical yielding criterion,mechanical yielding criterion and isotropic hardening model are established.The flow theory in incremental forms in polarization procedure is presented.The nonlinear constitutive law for electrical-mechanical coupling is proposed phenomenologically.Finally,the nonlinear constitutive law expressed in a form of matrices and vectors,which is immediately associated with finite element analysis,is formulated.In the example problem of a rectangular specimen subjected to a uniaxial electric field,the procedure from virgin state to fully polarized state is simulated.Afterward,a uniaxial compressive loading is applied to depolarizing the specimen.Results are in agreement with the experimental data.

  17. Nonlinear constitutive law for ferroelectric/ferroelastic material and its finite element realization

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The hysteresis phenomena of ferroelectric/ferroelastic material in polarization procedure are investigated. Some assumptions are presented based on the published experimental data. The electrical yielding criterion, mechanical yielding criterion and isotropic hardening model are established. The flow theory in incremental forms in polarization procedure is presented. The nonlinear constitutive law for electrical-mechanical coupling is proposed phenomenologically. Finally, the nonlinear constitutive law expressed in a form of matrices and vectors, which is immediately associated with finite element analysis, is formulated. In the example problem of a rectangular specimen subjected to a uniaxial electric field, the procedure from virgin state to fully polarized state is simulated. Afterward, a uniaxial compressive loading is applied to depolarizing the specimen. Results are in agreement with the experimental data.

  18. Ultrafast Z-scan measurements of nonlinear optical constants of window materials at 772, 1030, and 1550 nm.

    Science.gov (United States)

    Flom, Steven R; Beadie, Guy; Bayya, Shyam S; Shaw, Brandon; Auxier, Jason M

    2015-11-01

    Femtosecond Z-scan measurements have been performed on six window materials at 772, 1030, and 1550 nm. Measurements of the nonlinear refractive index are presented for reference materials, fused silica and BK7 and four near-infrared window materials, multispectral ZnS (CLEARTRAN), aluminum oxynitride (AlON), spinel (MgAl2O4) ceramic, and barium gallogermanate (BGG) glass.

  19. GEOMETRIC AND MATERIAL NONLINEAR ANALYSIS OF REINFORCED CONCRETE SLABS AT FIRE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Ayad A. Abdul -Razzak

    2013-05-01

    Full Text Available In the present study a nonlinear finite element analysis is presented  to predict the fire resistance of reinforced concrete slabs at fire environment. An eight node layered degenerated shell element utilizing Mindlin/Reissner thick plate theory is employed. The proposed model considered cracking, crushing and yielding of concrete and steel at elevated temperatures. The layered approach is used to represent the steel reinforcement and discretize the concrete slab through the thickness. The reinforcement steel is represented as a smeared layer of equivalent thickness with uniaxial strength and rigidity properties.Geometric nonlinear analysis may play an important role in the behavior of reinforced concrete slabs at high temperature. Geometrical nonlinearity in the layered approach is considered in the mathematical model, which is based on the total Lagrangian approach taking into account Von Karman assumptions.Finally two examples for which experimental results are available are analyzed, using the proposed model .The comparison showed good agreement with experimental results. 

  20. A novel class of nonlinear optical materials based on host-guest composites: zeolites as inorganic crystalline hosts.

    Science.gov (United States)

    Kim, Hyun Sung; Pham, Tung Cao Thanh; Yoon, Kyung Byung

    2012-05-16

    The demand for nonlinear optical (NLO) materials with exceptional NLO properties is very large, and hence the search for such materials should be continued not only to enhance their functions in current applications but also to help expedite the materialization of photonics in which photons instead of electrons are used for signal processing, transmission, and storage. This article summarizes the preparation, characteristics, and the future perspectives of novel second order nonlinear optical (2NLO) materials prepared by orientation-controlled incorporation of 2NLO molecules into zeolite channels and third order nonlinear optical (3NLO) materials prepared by compartmentalization of very small (<1.3 nm) PbS QDs within zeolite nanopores under different environments, and the novel chemistry newly unveiled during the preparation of novel zeolite based NLO materials. This journal is © The Royal Society of Chemistry 2012

  1. Nonlinear analysis of pile load-settlement behavior in layered soil

    Institute of Scientific and Technical Information of China (English)

    吕述晖; 王奎华; 张鹏; C. J. LEO3

    2015-01-01

    A simplified approach is presented to analyze the single pile settlement in multilayered soil. First, a fictitious soil−pile model is employed to consider the effect of layered soil beneath pile toe on pile settlement behavior. Two approximation methods are proposed to simplify the nonlinear load transfer function and simulate the nonlinear compression of fictitious soil−pile, respectively. On this basis, an efficient program is developed. The procedures for determining the main parameters of mathematical model are discussed. Comparisons with two well-documented field experimental pile loading tests are conducted to verify the rationality of the present method. Further studies are also made to evaluate the practicability of the proposed approach when a soft substratum exists, and the results suggest that the proposed method can provide a constructive means for assessing the settlement of a single pile for use in engineering design.

  2. Measurement of nonlinear optical refraction of composite material based on sapphire with silver by Kerr-lens autocorrelation method.

    Science.gov (United States)

    Yu, Xiang-xiang; Wang, Yu-hua

    2014-01-13

    Silver nanoparticles synthesized in a synthetic sapphire matrix were fabricated by ion implantation using the metal vapor vacuum arc ion source. The optical absorption spectrum of the Ag: Al2O3 composite material has been measured. The analysis of the supercontinuum spectrum displayed the nonlinear refractive property of this kind of sample. Nonlinear optical refraction index was identified at 800 nm excitation using the Kerr-lens autocorrelation (KLAC) technique. The spectrum showed that the material possessed self-defocusing property (n(2) = -1.1 × 10(-15) cm(2)W). The mechanism of nonlinear refraction has been discussed.

  3. Nonlinear dynamics of structures

    CERN Document Server

    Oller, Sergio

    2014-01-01

    This book lays the foundation of knowledge that will allow a better understanding of nonlinear phenomena that occur in structural dynamics.   This work is intended for graduate engineering students who want to expand their knowledge on the dynamic behavior of structures, specifically in the nonlinear field, by presenting the basis of dynamic balance in non‐linear behavior structures due to the material and kinematics mechanical effects.   Particularly, this publication shows the solution of the equation of dynamic equilibrium for structure with nonlinear time‐independent materials (plasticity, damage and frequencies evolution), as well as those time dependent non‐linear behavior materials (viscoelasticity and viscoplasticity). The convergence conditions for the non‐linear dynamic structure solution  are studied, and the theoretical concepts and its programming algorithms are presented.  

  4. Nonlinear behavior of ionically and covalently cross-linked alginate hydrogels

    Science.gov (United States)

    Hashemnejad, Seyedmeysam; Zabet, Mahla; Kundu, Santanu

    2015-03-01

    Gels deform differently under applied load and the deformation behavior is related to their network structures and environmental conditions, specifically, strength and density of crosslinking, polymer concentration, applied load, and temperature. Here, we investigate the mechanical behavior of both ionically and covalent cross-linked alginate hydrogel using large amplitude oscillatory shear (LAOS) and cavitation experiments. Ionically-bonded alginate gels were obtained by using divalent calcium. Alginate volume fraction and alginate to calcium ratio were varied to obtain gels with different mechanical properties. Chemical gels were synthesized using adipic acid dihdrazide (AAD) as a cross-linker. The non-linear rheological parameters are estimated from the stress responses to elucidate the strain softening behavior of these gels. Fracture initiation and propagation mechanism during shear rheology and cavitation experiments will be presented. Our results provide a better understanding on the deformation mechanism of alginate gel under large-deformation.

  5. Structure dynamics with regard to non-linear support behavior; Dynamische Strukturberechnung unter Beruecksichtigung nichtlinearen Lagerverhaltens

    Energy Technology Data Exchange (ETDEWEB)

    Driessen, W. [Technischer Ueberwachungs-Verein Nord e.V., Hamburg (Germany)

    2000-07-01

    Because of modifications to a feed-water line of a power plant structural calculations of the pipework were performed. As a result of a linear (modal) analysis very high restraint forces on the supports were calculated. In order to reduce conservatisms in the calculation the model was optimized with regard to the support stiffnesses and nonlinear behavior of slide bearings, guides and shock absorbers were taken into account. The main result of the non-linear analysis, which was performed by methods of direct-integration, was that nonlinearity yields evident differences in structural frequencies and in energy dissipation (damping) in comparison to the linear analysis. The high restraint forces on the supports became smaller for most of the supports but at some points the forces of the non-linear analysis were even higher. So the conservatism of the linear analysis is not fully valid for the whole structure. The relevance of the non-linear effects in dynamic piping calculations is shown by comparing the calculation result with measurements which were performed on structures in the plant. (orig.) [German] Im Rahmen der Aenderung der Speisewasserleitung einer Kraftwerksanlage wurde die Struktur neu berechnet. Die Analysen mit einem linearen Modell (modal), das ueblicherweise verwendet wird, ergaben hohe Lasten an Halterungen. Zum Abbau von Konservativitaeten wurde eine realistischere Modellierung durch die Beruecksichtigung des nichtlinearen Verhaltens der in der Anlage befindlichen Gleitlager, Fuehrungen und Stossbremsen in der Berechnung vorgenommen. Die Untersuchungen haben ergeben, dass durch die Nichtlinearitaet das Frequenzverhalten der Struktur und die Dissipation von Energie durch Reibvorgaenge wesentlich beeinflusst werden. Des Weiteren ist festzustellen, dass aus linearen Analysen nicht uneingeschraenkt konservative Ergebnisse gewonnen werden. Die Relevanz der Beruecksichtigung des nichtlinearen Lagerverhaltens bei einer dynamischen Strukturberechnung wird

  6. A review of predictive nonlinear theories for multiscale modeling of heterogeneous materials

    Science.gov (United States)

    Matouš, Karel; Geers, Marc G. D.; Kouznetsova, Varvara G.; Gillman, Andrew

    2017-02-01

    Since the beginning of the industrial age, material performance and design have been in the midst of innovation of many disruptive technologies. Today's electronics, space, medical, transportation, and other industries are enriched by development, design and deployment of composite, heterogeneous and multifunctional materials. As a result, materials innovation is now considerably outpaced by other aspects from component design to product cycle. In this article, we review predictive nonlinear theories for multiscale modeling of heterogeneous materials. Deeper attention is given to multiscale modeling in space and to computational homogenization in addressing challenging materials science questions. Moreover, we discuss a state-of-the-art platform in predictive image-based, multiscale modeling with co-designed simulations and experiments that executes on the world's largest supercomputers. Such a modeling framework consists of experimental tools, computational methods, and digital data strategies. Once fully completed, this collaborative and interdisciplinary framework can be the basis of Virtual Materials Testing standards and aids in the development of new material formulations. Moreover, it will decrease the time to market of innovative products.

  7. A review of predictive nonlinear theories for multiscale modeling of heterogeneous materials

    Energy Technology Data Exchange (ETDEWEB)

    Matouš, Karel, E-mail: kmatous@nd.edu [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States); Geers, Marc G.D.; Kouznetsova, Varvara G. [Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven (Netherlands); Gillman, Andrew [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2017-02-01

    Since the beginning of the industrial age, material performance and design have been in the midst of innovation of many disruptive technologies. Today's electronics, space, medical, transportation, and other industries are enriched by development, design and deployment of composite, heterogeneous and multifunctional materials. As a result, materials innovation is now considerably outpaced by other aspects from component design to product cycle. In this article, we review predictive nonlinear theories for multiscale modeling of heterogeneous materials. Deeper attention is given to multiscale modeling in space and to computational homogenization in addressing challenging materials science questions. Moreover, we discuss a state-of-the-art platform in predictive image-based, multiscale modeling with co-designed simulations and experiments that executes on the world's largest supercomputers. Such a modeling framework consists of experimental tools, computational methods, and digital data strategies. Once fully completed, this collaborative and interdisciplinary framework can be the basis of Virtual Materials Testing standards and aids in the development of new material formulations. Moreover, it will decrease the time to market of innovative products.

  8. Nonlinear Peltier effect in semiconductors

    Science.gov (United States)

    Zebarjadi, Mona; Esfarjani, Keivan; Shakouri, Ali

    2007-09-01

    Nonlinear Peltier coefficient of a doped InGaAs semiconductor is calculated numerically using the Monte Carlo technique. The Peltier coefficient is also obtained analytically for single parabolic band semiconductors assuming a shifted Fermi-Dirac electronic distribution under an applied bias. Analytical results are in agreement with numerical simulations. Key material parameters affecting the nonlinear behavior are doping concentration, effective mass, and electron-phonon coupling. Current density thresholds at which nonlinear behavior is observable are extracted from numerical data. It is shown that the nonlinear Peltier effect can be used to enhance cooling of thin film microrefrigerator devices especially at low temperatures.

  9. Flexural fatigue life prediction of closed hat-section using materially nonlinear axial fatigue characteristics

    Science.gov (United States)

    Razzaq, Zia

    1989-01-01

    Straight or curved hat-section members are often used as structural stiffeners in aircraft. For instance, they are employed as stiffeners for the dorsal skin as well as in the aerial refueling adjacent area structure in F-106 aircraft. The flanges of the hat-section are connected to the aircraft skin. Thus, the portion of the skin closing the hat-section interacts with the section itself when resisting the stresses due to service loads. The flexural fatigue life of such a closed section is estimated using materially nonlinear axial fatigue characteristics. It should be recognized that when a structural shape is subjected to bending, the fatigue life at the neutral axis is infinity since the normal stresses are zero at that location. Conversely, the fatigue life at the extreme fibers where the normal bending stresses are maximum can be expected to be finite. Thus, different fatigue life estimates can be visualized at various distances from the neural axis. The problem becomes compounded further when significant portions away from the neutral axis are stressed into plastic range. A theoretical analysis of the closed hat-section subjected to flexural cyclic loading is first conducted. The axial fatigue characteristics together with the related axial fatigue life formula and its inverted form given by Manson and Muralidharan are adopted for an aluminum alloy used in aircraft construction. A closed-form expression for predicting the flexural fatigue life is then derived for the closed hat-section including materially nonlinear action. A computer program is written to conduct a study of the variables such as the thicknesses of the hat-section and the skin, and the type of alloy used. The study has provided a fundamental understanding of the flexural fatigue life characteristics of a practical structural component used in aircraft when materially nonlinear action is present.

  10. Prediction of nonlinear optical properties of organic materials. General theoretical considerations

    Science.gov (United States)

    Cardelino, B.; Moore, C.; Zutaut, S.

    1993-01-01

    The prediction of nonlinear optical properties of organic materials is geared to assist materials scientists in the selection of good candidate molecules. A brief summary of the quantum mechanical methods used for estimating hyperpolarizabilities will be presented. The advantages and limitations of each technique will be discussed. Particular attention will be given to the finite-field method for calculating first and second order hyperpolarizabilities, since this method is better suited for large molecules. Corrections for dynamic fields and bulk effects will be discussed in detail, focusing on solvent effects, conformational isomerization, core effects, dispersion, and hydrogen bonding. Several results will be compared with data obtained from third-harmonic-generation (THG) and dc-induced second harmonic generation (EFISH) measurements. These comparisons will demonstrate the qualitative ability of the method to predict the relative strengths of hyperpolarizabilities of a class of compounds. The future application of molecular mechanics, as well as other techniques, in the study of bulk properties and solid state defects will be addressed. The relationship between large values for nonlinear optical properties and large conjugation lengths is well known, and is particularly important for third-order processes. For this reason, the materials with the largest observed nonresonant third-order properties are conjugated polymers. An example of this type of polymer is polydiacetylene. One of the problems in dealing with polydiacetylene is that substituents which may enhance its nonlinear properties may ultimately prevent it from polymerizing. A model which attempts to predict the likelihood of solid-state polymerization is considered, along with the implications of the assumptions that are used. Calculations of the third-order optical properties and their relationship to first-order properties and energy gaps will be discussed. The relationship between monomeric and

  11. First principles crystal engineering of nonlinear optical materials. I. Prototypical case of urea

    Science.gov (United States)

    Masunov, Artëm E.; Tannu, Arman; Dyakov, Alexander A.; Matveeva, Anastasia D.; Freidzon, Alexandra Ya.; Odinokov, Alexey V.; Bagaturyants, Alexander A.

    2017-06-01

    The crystalline materials with nonlinear optical (NLO) properties are critically important for several technological applications, including nanophotonic and second harmonic generation devices. Urea is often considered to be a standard NLO material, due to the combination of non-centrosymmetric crystal packing and capacity for intramolecular charge transfer. Various approaches to crystal engineering of non-centrosymmetric molecular materials were reported in the literature. Here we propose using global lattice energy minimization to predict the crystal packing from the first principles. We developed a methodology that includes the following: (1) parameter derivation for polarizable force field AMOEBA; (2) local minimizations of crystal structures with these parameters, combined with the evolutionary algorithm for a global minimum search, implemented in program USPEX; (3) filtering out duplicate polymorphs produced; (4) reoptimization and final ranking based on density functional theory (DFT) with many-body dispersion (MBD) correction; and (5) prediction of the second-order susceptibility tensor by finite field approach. This methodology was applied to predict virtual urea polymorphs. After filtering based on packing similarity, only two distinct packing modes were predicted: one experimental and one hypothetical. DFT + MBD ranking established non-centrosymmetric crystal packing as the global minimum, in agreement with the experiment. Finite field approach was used to predict nonlinear susceptibility, and H-bonding was found to account for a 2.5-fold increase in molecular hyperpolarizability to the bulk value.

  12. Analysis of contributions of nonlinear material constants to temperature-induced velocity shifts of quartz surface acoustic wave resonators.

    Science.gov (United States)

    Zhang, Haifeng; Kosinski, John A; Zuo, Lei

    2016-09-01

    In this paper, we examine the significance of the various higher-order effects regarding calculating temperature behavior from a set of material constants and their temperature coefficients. Temperature-induced velocity shifts have been calculated for quartz surface acoustic wave (SAW) resonators and the contributions of different groups of nonlinear material constants (third-order elastic constants (TOE), third-order piezoelectric constants (TOP), third-order dielectric constants (TOD) and electrostrictive constants (EL)) to the temperature-induced velocity shifts have been analyzed. The analytical methodology has been verified through the comparison of experimental and analytical results for quartz resonators. In general, the third-order elastic constants were found to contribute most significantly to the temperature-induced shifts in the SAW velocity. The contributions from the third-order dielectric constants and electrostrictive constants were found to be negligible. For some specific cases, the third-order piezoelectric constants were found to make a significant contribution to the temperature-induced shifts. The significance of each third-order elastic constant as a contributor to the temperature-velocity effect was analyzed by applying a 10% variation to each of the third-order elastic constants separately. Additionally, we have considered the issues arising from the commonly used thermoelastic expansions that provide a good but not exact description of the temperature effects on frequency in piezoelectric resonators as these commonly used expansions do not include the effects of higher-order material constants.

  13. Effects of transverse profile of pump field on second harmonic generation in periodic nonlinear materials

    Institute of Scientific and Technical Information of China (English)

    GaoJin-Yue; ZhangHan-Zhuang; YangJian-Bing

    2003-01-01

    We report on a theoreticalanalysis of the effects of a converging pump field of Gaussian transverse profile on second harmonic generation in a periodic nonlinear material with quasi-phase-matching. The outputs of the centre intensity and the intensity flux for second harmonic generation are derived by simulation, based on the parameters of quasi-phase-mismatch, the waist and focus positions of the input pump beam. The results show that when the transverse profile of the pump field is taken into account, the quasi-phase-match value and focus position of input beam for maximal second harmonic generation flollow new criteria.

  14. Effects of transverse profile of pump field on second harmonic generation in periodic nonlinear materials

    Institute of Scientific and Technical Information of China (English)

    张汉壮; 杨建冰; 高锦岳

    2003-01-01

    We report on a theoretical analysis of the effects of a converging pump field of Gaussian transverse profile on second harmonic generation in a periodic nonlinear material with quasi-phase-matching. The outputs of the centre intensity and the intensity flux for second harmonic generation are derived by simulation, based on the parameters of quasi-phase-mismatch, the waist and focus positions of the input pump beam. The results show that when the transverse profile of the pump field is taken into account, the quasi-phase-match value and focus position of input beam for maximal second harmonic generation follow new criteria.

  15. Experimental parameter estimation method for nonlinear viscoelastic composite material models: an application on arterial tissue.

    Science.gov (United States)

    Sunbuloglu, Emin; Bozdag, Ergun; Toprak, Tuncer; Islak, Civan

    2013-01-01

    This study is aimed at setting a method of experimental parameter estimation for large-deforming nonlinear viscoelastic continuous fibre-reinforced composite material model. Specifically, arterial tissue was investigated during experimental research and parameter estimation studies, due to medical, scientific and socio-economic importance of soft tissue research. Using analytical formulations for specimens under combined inflation/extension/torsion on thick-walled cylindrical tubes, in vitro experiments were carried out with fresh sheep arterial segments, and parameter estimation procedures were carried out on experimental data. Model restrictions were pointed out using outcomes from parameter estimation. Needs for further studies that can be developed are discussed.

  16. An all-optical matrix multiplication scheme with non-linear material based switching system

    Institute of Scientific and Technical Information of China (English)

    Archan Kumar Das; Sourangshu Mukhopadhyay

    2005-01-01

    Optics is a potential candidate in information, data, and image processing. In all-optical data and information processing, optics has been used as information carrying signal because of its inherent advantages of parallelism. Several optical methods are proposed in support of the above processing. In many algebraic,arithmetic, and image processing schemes fundamental logic and memory operations are conducted exploring all-optical devices. In this communication we report an all-optical matrix multiplication operation with non-linear material based switching circuit.

  17. Strength of anisotropy in a granular material: Linear versus nonlinear contact model.

    Science.gov (United States)

    La Ragione, Luigi; Gammariello, Marica; Recchia, Giuseppina

    2016-12-01

    In this paper, we deal with anisotropy in an idealized granular material made of a collection of frictional, elastic, contacting particles. We present a theoretical analysis for an aggregate of particles isotropically compressed and then sheared, in which two possible contacts laws between particles are considered: a linear contact law, where the contact stiffness is constant; and a nonlinear contact law, where the contact stiffness depends on the overlapping between particles. In the former case the anisotropy observed in the aggregate is associated with particle arrangement. In fact, although the aggregate is initially characterized by an isotropic network of contacts, during the loading, an anisotropic texture develops, which is measured by a fabric tensor. With a nonlinear contact law it is possible to develop anisotropy because contacting stiffnesses are different, depending on the orientation of the contact vectors with respect to the axis of the applied deformation. We find that before the peak load is reached, an aggregate made of particles with a linear contact law develops a much smaller anisotropy compared with that of an aggregate with a nonlinear law.

  18. Strength of anisotropy in a granular material: Linear versus nonlinear contact model

    Science.gov (United States)

    La Ragione, Luigi; Gammariello, Marica; Recchia, Giuseppina

    2016-12-01

    In this paper, we deal with anisotropy in an idealized granular material made of a collection of frictional, elastic, contacting particles. We present a theoretical analysis for an aggregate of particles isotropically compressed and then sheared, in which two possible contacts laws between particles are considered: a linear contact law, where the contact stiffness is constant; and a nonlinear contact law, where the contact stiffness depends on the overlapping between particles. In the former case the anisotropy observed in the aggregate is associated with particle arrangement. In fact, although the aggregate is initially characterized by an isotropic network of contacts, during the loading, an anisotropic texture develops, which is measured by a fabric tensor. With a nonlinear contact law it is possible to develop anisotropy because contacting stiffnesses are different, depending on the orientation of the contact vectors with respect to the axis of the applied deformation. We find that before the peak load is reached, an aggregate made of particles with a linear contact law develops a much smaller anisotropy compared with that of an aggregate with a nonlinear law.

  19. Nonlinear waves in lattice materials: Adaptively augmented directivity and functionality enhancement by modal mixing

    Science.gov (United States)

    Ganesh, R.; Gonella, S.

    2017-02-01

    The motive of this work is to understand the complex spatial characteristics of finite-amplitude elastic wave propagation in periodic structures and leverage the unique opportunities offered by nonlinearity to activate complementary functionalities and design adaptive spatial wave manipulators. The underlying assumption is that the magnitude of wave propagation is small with respect to the length scale of the structure under consideration, albeit large enough to elicit the effects of finite deformation. We demonstrate that the interplay of dispersion, nonlinearity and modal complexity involved in the generation and propagation of higher harmonics gives rise to secondary wave packets that feature multiple characteristics, one of which conforms to the dispersion relation of the corresponding linear structure. This provides an opportunity to engineer desired wave characteristics through a geometric and topological design of the unit cell, and results in the ability to activate complementary functionalities, typical of high frequency regimes, while operating at low frequencies of excitation - an effect seldom observed in linear periodic structures. The ability to design adaptive switches is demonstrated here using lattice configurations whose response is characterized by geometric and/or material nonlinearities.

  20. Evaluating Emotional and Biological Sensitivity to Maternal Behavior Among Self-Injuring and Depressed Adolescent Girls Using Nonlinear Dynamics

    DEFF Research Database (Denmark)

    Crowe, Sheila E; Butner, Jonathan E.; Wiltshire, Travis

    2017-01-01

    High sensitivity and reactivity to behaviors of family members characterize several forms of psychopathology, including self-inflicted injury (SII). We examined mother-daughter behavioral and psychophysiological reactivity during a conflict discussion using nonlinear dynamics to assess asymmetrical...... would not evoke mothers’ behavioral or physiological reactivity, and (c) control teens and mothers would be less reactive, with no dynamic associations in either direction. Convergent cross-mapping with dewdrop regression, which identifies directional associations, indicated that mothers’ behaviors...

  1. A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage

    Science.gov (United States)

    Yang, Z.; Chen, H.; Yu, T.; Li, B.

    2016-08-01

    The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software tema Motion is used to track the spot which marked the cage surface. Finally, by developing the matlab program, a Lissajous' figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage.

  2. A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage.

    Science.gov (United States)

    Yang, Z; Chen, H; Yu, T; Li, B

    2016-08-01

    The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software tema Motion is used to track the spot which marked the cage surface. Finally, by developing the matlab program, a Lissajous' figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage.

  3. Tribological Behavior of Journal Bearing Material under Different Lubricants

    Directory of Open Access Journals (Sweden)

    S. Baskar

    2014-06-01

    Full Text Available The friction and wear behavior of journal bearing material has been investigated using pin on disc wear tester with three different lubricating oils i.e. synthetic lubricating oil (SAE20W40, chemically modified rapeseed oil (CMRO, chemically modified rapeseed oil with Nano CuO. Wear tests were carried out at maximum load of 200 N and sliding speeds of 2 – 10 m/s. The results showed that the friction and wear behavior of the journal bearing material have changed according to the sliding conditions and lubricating oils. The journal bearing material has a lower friction coefficient for CMRO with Nano CuO than other two oils. Higher wear of journal bearing material was observed in SAE 20W40 and CMRO. Worn surfaces of the journal bearing material with three lubricating oils were examined using scanning electron microscope (SEM and wear mechanisms were discussed.

  4. A new model for analyzing nonlinear torsion behavior of concrete filled steel tube columns with rectangular section

    Science.gov (United States)

    Wang, Yuhang; Nie, Jianguo; Fan, Jiansheng

    2016-06-01

    An experimental study on concrete filled steel tube columns with rectangular section subjected to compressionflexure-torsion combined action has been carried out. The failure modes and load-deformation hysteretic relations were obtained. Based on the principles of classical material mechanics, the relations between the torsion curvature of the section and the shear strain of the fiber on the section were established. Then the strain distribution on the rectangular section of concrete filled steel tube columns subjected to torsion was analyzed. The three-dimensional refined finite element model was also built, in order to make the precision verification. The matrix forms of the relation between the torsion curvature of the section and the shear strain of the fiber on the section were derived, and introduced into the fiber beam model considering nonlinear torsion effect on the section. The comparison between test results and calculation results showed that the fiber beam model considering nonlinear torsion effect had high modeling efficiency and solution precision for predicting the torsion behavior of concrete filled steel tube columns with rectangular sections, and was suitable for analyzing the dynamic response of various structures subjected to the combined cyclic load caused by the earthquake load.

  5. Fluorooxoborates: Beryllium-Free Deep-Ultraviolet Nonlinear Optical Materials without Layered Growth.

    Science.gov (United States)

    Zhang, Bingbing; Shi, Guoqiang; Yang, Zhihua; Zhang, Fangfang; Pan, Shilie

    2017-03-27

    Deep-ultraviolet nonlinear optical (DUV NLO) crystals are the key materials to extend the output range of solid-state lasers to below 200 nm. The only practical material KBe2 BO3 F2 suffers high toxicity through beryllium and strong layered growth. Herein, we propose a beryllium-free material design and synthesis strategy for DUV NLO materials. Introducing the (BO3 F)(4-) , (BO2 F2 )(3-) , and (BOF3 )(2-) groups in borates could break through the fixed 3D B-O network that would produce a larger birefringence without layering and simultaneously keep a short cutoff edge down to DUV. The theoretical and experimental studies on a series of fluorooxoborates confirm this strategy. Li2 B6 O9 F2 is identified as a DUV NLO material with a large second harmonic generation efficiency (0.9×KDP) and a large predicted birefringence (0.07) without layering. This study provides a feasible way to break down the DUV wall for NLO materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Structural, optical, thermal and mechanical characterization of an organic nonlinear optical material: 4-methyl-3-nitrobenzoic acid single crystal

    Science.gov (United States)

    Bharathi, M. Divya; Ahila, G.; Mohana, J.; Chakkaravarthi, G.; Anbalagan, G.

    2016-11-01

    Organic single crystals of 4-methyl-3-nitrobenzoic acid (4M3N) have been grown by slow evaporation solution growth technique at room temperature. The single crystal X-ray diffraction study reveals that 4M3N crystallizes in monoclinic system with space group P21/n. The crystalline perfection of the crystal was analyzed by high resolution X-ray diffraction (HRXRD) measurements. The functional groups present in 4M3N have been identified from FT-IR and FT-Raman spectra. The lower cut-off wavelength of 4M3N is found to be 404 nm and the optical band gap is calculated as 2.91 eV. The refractive index shows normal behavior with wavelength. The physio chemical changes, decomposition and stability of the 4M3N compound were established by TG-DTA studies. Vickers microhardness measurement concludes that 4M3N belongs to soft material (n=2.5) category. The LDT value is found to be higher than that of KDP and some of the important organic NLO materials. The third order nonlinear refractive index and nonlinear absorption coefficient of the 4M3N have been measured by Z-scan studies. The imaginary and real parts of the third-order susceptibility values were determined as Im χ3=9.129×10-11 esu and Re χ3=1.4034×10-9 esu respectively. The dislocation density was calculated to be 3.0448×106 cm-2 which indicates the quality of the crystal.

  7. A continuous nonlinear model approach to study the behavior of large signal DC to DC converters

    Science.gov (United States)

    Guinjoan, Francisco

    The study of signal switching DC-DC converters behavior is addressed. Given the fact that the linear methods cannot be used in this case, a nonlinear model was developed. The power stage nonlinear continuous model, which can be applied in both conduction modes (continuous and discontinuous), is obtained from the partition of the characteristic state vector variables in two subsets. This method is applied to the elementary switching cells (buck, boost, and buck-boost) and Cuk converter. It is oriented to the fast numerical simulation by means of general purpose simulation programs. Different results from numerical simulations, confirming the accuracy of the method used, either in an open loop or in a closed loop, are obtained, provided the validity of its domain is respected. The nonlinear model linearization made it possible to obtain equivalent transmittances for the DC-DC converters. Its application to a boost converter operating in the discontinuous condition mode at variable frequency rate enables the comparison of the obtained results with other existing methods and equivalence between the two of them to be easily established. The revision of the initial hypothesis leads to the establishment of a small signal model valid in the high frequency domain and to the results obtained being derived in a more systematic way. A model for switching DC-DC converters is given. Its validity is established, whatever its order and conduction modes, either in an open loop or a closed loop.

  8. Time-Dependent Behavior of Diabase and a Nonlinear Creep Model

    Science.gov (United States)

    Yang, Wendong; Zhang, Qiangyong; Li, Shucai; Wang, Shugang

    2014-07-01

    Triaxial creep tests were performed on diabase specimens from the dam foundation of the Dagangshan hydropower station, and the typical characteristics of creep curves were analyzed. Based on the test results under different stress levels, a new nonlinear visco-elasto-plastic creep model with creep threshold and long-term strength was proposed by connecting an instantaneous elastic Hooke body, a visco-elasto-plastic Schiffman body, and a nonlinear visco-plastic body in series mode. By introducing the nonlinear visco-plastic component, this creep model can describe the typical creep behavior, which includes the primary creep stage, the secondary creep stage, and the tertiary creep stage. Three-dimensional creep equations under constant stress conditions were deduced. The yield approach index (YAI) was used as the criterion for the piecewise creep function to resolve the difficulty in determining the creep threshold value and the long-term strength. The expression of the visco-plastic component was derived in detail and the three-dimensional central difference form was given. An example was used to verify the credibility of the model. The creep parameters were identified, and the calculated curves were in good agreement with the experimental curves, indicating that the model is capable of replicating the physical processes.

  9. DNA-based polymers as chiral templates for second-order nonlinear optical materials.

    Science.gov (United States)

    Wanapun, Duangporn; Hall, Victoria J; Begue, Nathan J; Grote, James G; Simpson, Garth J

    2009-10-19

    The unique symmetry properties of chiral systems allow the emergence of coherent second harmonic generation in polymeric materials lacking polar order. Deoxyribonucleic acid (DNA) treated with the surfactant cetyltrimethylammonium (CTMA) was drop-cast to spontaneously form films that are active for coherent second harmonic generation (SHG). SHG images acquired as a function of incident and exigent polarization are in good agreement with theoretical predictions assuming nonpolar D(infinity) symmetry for the double-stranded DNA chains. Doping the DNA films with crystal violet substantially increases the efficiency of SHG, but does not significantly alter the polarization-dependence, suggesting that the SHG generated upon doping arises from the same chiral-specific origin, presumably templated by the DNA. These results raise the possibility of new design strategies for organic nonlinear optical materials based on soft chiral polymers that do not require polar order.

  10. Non-linear, visual-rich supplemental material designed for an introductory course in veterinary anesthesia.

    Science.gov (United States)

    Dyson, Doris H

    2003-01-01

    A possible reason for superficial learning in an introductory anesthesia course was considered to be a lack of visual reinforcement at the time of examination preparation. Students had limited access to live animal laboratories and clinical cases during the course, reducing their ability to depend on experiential learning. In an attempt to improve student learning, simple presentation software was used to develop a supplemental CD. The design involved multiple PowerPoint presentations that incorporated text, pictures, videos, and self-assessments. Non-linear exploration of the topics covered was made possible by extensive use of hyperlinks within and between presentations, moving the student to definitions, background material, videos, advanced details, and previously covered information. Comments received from students on a prototype were positive overall, and improvements were made related to their feedback. Other supplemental materials and lecture presentations can easily incorporate the techniques described here.

  11. Performance analysis of flow lines with non-linear flow of material

    CERN Document Server

    Helber, Stefan

    1999-01-01

    Flow line design is one of the major tasks in production management. The decision to install a set of machines and buffers is often highly irreversible. It determines both cost and revenue to a large extent. In order to assess the economic impact of any possible flow line design, production rates and inventory levels have to be estimated. These performance measures depend on the allocation of buffers whenever the flow of material is occasionally disrupted, for example due to machine failures or quality problems. The book describes analytical methods that can be used to evaluate flow lines much faster than with simulation techniques. Based on these fast analytical techniques, it is possible to determine a flow line design that maximizes the net present value of the flow line investment. The flow of material through the line may be non-linear, for example due to assembly operations or quality inspections.

  12. Solution Growth of a Novel Nonlinear Optical Material: L-Histidine Tetrafluoroborate

    Science.gov (United States)

    Aggarwal, M. D.; Choi, J.; Wang, W. S.; Bhat, K.; Lal, R. B.; Shields, Angela D.; Penn, Benjamin G.; Frazier, Donald O.

    1998-01-01

    Single crystals of L-Histidine tetrafluoroborate (L-HFB), a semiorganic nonlinear optical (NLO) material have been successfully grown by the temperature lowering and evaporation methods in our laboratory. Solubility curves of L-HFB have been determined in different solvents, such as water, ethanol and acetone. The solubility of L-HFB is very low in acetone, and ethanol, therefore, it is not feasible to grow L-HFB single crystals using these solvents. Good quality single crystals of a novel nonlinear optical material L-HFB have been grown from aqueous solution. Effects of seed orientation on morphologies of L-HFB crystals were studied. The advantages and disadvantage of both the evaporation and the temperature lowering techniques are compared. The single crystals in size 20 x 20 x 10 cubic mm were grown with deionized water as solvent in two weeks with an approximate growth rate of 1.4mm/day. The transmission range for these crystals has been found to be from 250 nm to 1500 nm.

  13. A nonlinear dynamical system approach for the yielding behaviour of a viscoplastic material.

    Science.gov (United States)

    Burghelea, Teodor; Moyers-Gonzalez, Miguel; Sainudiin, Raazesh

    2017-02-15

    A nonlinear dynamical system model that approximates a microscopic Gibbs field model for the yielding of a viscoplastic material subjected to varying external stresses recently reported in R. Sainudiin, M. Moyers-Gonzalez and T. Burghelea, Soft Matter, 2015, 11(27), 5531-5545 is presented. The predictions of the model are in fair agreement with microscopic simulations and are in very good agreement with the micro-structural semi-empirical model reported in A. M. V. Putz and T. I. Burghelea, Rheol. Acta, 2009, 48, 673-689. With only two internal parameters, the nonlinear dynamical system model captures several key features of the solid-fluid transition observed in experiments: the effect of the interactions between microscopic constituents on the yield point, the abruptness of solid-fluid transition and the emergence of a hysteresis of the micro-structural states upon increasing/decreasing external forces. The scaling behaviour of the magnitude of the hysteresis with the degree of the steadiness of the flow is consistent with previous experimental observations. Finally, the practical usefulness of the approach is demonstrated by fitting a rheological data set measured with an elasto-viscoplastic material.

  14. Simulations of heart valves by thin shells with non-linear material properties

    Science.gov (United States)

    Borazjani, Iman; Asgharzadeh, Hafez; Hedayat, Mohammadali

    2016-11-01

    The primary function of a heart valve is to allow blood to flow in only one direction through the heart. Triangular thin-shell finite element formulation is implemented, which considers only translational degrees of freedom, in three-dimensional domain to simulate heart valves undergoing large deformations. The formulation is based on the nonlinear Kirchhoff thin-shell theory. The developed method is intensively validated against numerical and analytical benchmarks. This method is added to previously developed membrane method to obtain more realistic results since ignoring bending forces can results in unrealistic wrinkling of heart valves. A nonlinear Fung-type constitutive relation, based on experimentally measured biaxial loading tests, is used to model the material properties for response of the in-plane motion in heart valves. Furthermore, the experimentally measured liner constitutive relation is used to model the material properties to capture the flexural motion of heart valves. The Fluid structure interaction solver adopts a strongly coupled partitioned approach that is stabilized with under-relaxation and the Aitken acceleration technique. This work was supported by American Heart Association (AHA) Grant 13SDG17220022 and the Center of Computational Research (CCR) of University at Buffalo.

  15. A Distortion-Modified Free Volume Theory for Nonlinear Viscoelastic Behavior

    Science.gov (United States)

    Popelar, C. F.; Liechti, K. M.

    2003-06-01

    Many polymeric materials, including structural adhesives, exhibit anonlinear viscoelastic response. The nonlinear theory of Knauss and Emri(Polym. Engrg. Sci. 27, 1987, 87 100) is based on the Doolittle conceptthat the ‘free volume’ controls the mobility of polymer molecules and,thus, the inherent time scale of the material. It then follows thatfactors such as temperature and moisture, which change the free volume,will influence the time scale. Furthermore, stress-induced dilatationwill also affect the free volume and, hence, the time scale. However,during this investigation, dilatational effects alone were found to beinsufficient for describing the response of near pure shear tests of abisphenol A epoxy with amido amine hardener. Thus, the free volumeapproach presented here has been modified to include distortionaleffects in the inherent time scale of the material. The same was foundto be true for a urethane adhesive.

  16. Study on the nonlinear electromagnetic acoustic resonancee method for th evaluation of hidden damage in a metallic material

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seung Hyun; Park, Choon Su; Seo, Dae Cheol [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Cho, Seung Wan [Dept. of Mechanical Engineering, Sunngkyunkwan University, Suwon (Korea, Republic of); Jhang, Kyung Young [Dept. of Mechanical Engineering, Hanyang University, Seoul (Korea, Republic of)

    2014-08-15

    Recently, much attention has been paid to nonlinear ultrasonic technology as a potential tool to assess hidden damages that cannot be detected by conventional ultrasonic testing. One nonlinear ultrasonic technique is measurement of the resonance frequency shift, which is based on the hysteresis of the material elasticity. Sophisticated measurement of resonance frequency is required, because the change in resonance frequency is usually quite small. In this investigation, the nonlinear electromagnetic acoustic resonance (NEMAR) method was employed. The NEMAR method uses noncontact electromagnetic acoustic transducers (EMATs) in order to minimize the effect of the transducer on the frequency response of the object. Aluminum plate specimens that underwent three point bending fatigue were tested witha shear wave EMAT. The hysteretic nonlinear parameter α, a key indicator of damage, was calculated from the resonance frequency shift at several levels of input voltage. The hysteretic nonlinear parameter of a damaged sample was compared to that of an intact one, showing a difference in the values.

  17. Modeling high temperature materials behavior for structural analysis

    CERN Document Server

    Naumenko, Konstantin

    2016-01-01

    This monograph presents approaches to characterize inelastic behavior of materials and structures at high temperature. Starting from experimental observations, it discusses basic features of inelastic phenomena including creep, plasticity, relaxation, low cycle and thermal fatigue. The authors formulate constitutive equations to describe the inelastic response for the given states of stress and microstructure. They introduce evolution equations to capture hardening, recovery, softening, ageing and damage processes. Principles of continuum mechanics and thermodynamics are presented to provide a framework for the modeling materials behavior with the aim of structural analysis of high-temperature engineering components.

  18. Tribological Behavior of Journal Bearing Material under Different Lubricants

    OpenAIRE

    2014-01-01

    The friction and wear behavior of journal bearing material has been investigated using pin on disc wear tester with three different lubricating oils i.e. synthetic lubricating oil (SAE20W40), chemically modified rapeseed oil (CMRO), chemically modified rapeseed oil with Nano CuO. Wear tests were carried out at maximum load of 200 N and sliding speeds of 2 – 10 m/s. The results showed that the friction and wear behavior of the journal bearing material have changed according to the sliding cond...

  19. Nonlinear Socio-Ecological Dynamics and First Principles ofCollective Choice Behavior of ``Homo Socialis"

    Science.gov (United States)

    Sonis, M.

    Socio-ecological dynamics emerged from the field of Mathematical SocialSciences and opened up avenues for re-examination of classical problems of collective behavior in Social and Spatial sciences. The ``engine" of this collective behavior is the subjective mental evaluation of level of utilities in the future, presenting sets of composite socio-economic-temporal-locational advantages. These dynamics present new laws of collective multi-population behavior which are the meso-level counterparts of the utility optimization individual behavior. The central core of the socio-ecological choice dynamics includes the following first principle of the collective choice behavior of ``Homo Socialis" based on the existence of ``collective consciousness": the choice behavior of ``Homo Socialis" is a collective meso-level choice behavior such that the relative changes in choice frequencies depend on the distribution of innovation alternatives between adopters of innovations. The mathematical basis of the Socio-Ecological Dynamics includes two complementary analytical approaches both based on the use of computer modeling as a theoretical and simulation tool. First approach is the ``continuous approach" --- the systems of ordinary and partial differential equations reflecting the continuous time Volterra ecological formalism in a form of antagonistic and/or cooperative collective hyper-games between different sub-sets of choice alternatives. Second approach is the ``discrete approach" --- systems of difference equations presenting a new branch of the non-linear discrete dynamics --- the Discrete Relative m-population/n-innovations Socio-Spatial Dynamics (Dendrinos and Sonis, 1990). The generalization of the Volterra formalism leads further to the meso-level variational principle of collective choice behavior determining the balance between the resulting cumulative social spatio-temporal interactions among the population of adopters susceptible to the choice alternatives and the

  20. Synthesis, structure, linear and third-order nonlinear optical behavior of N-(3-hydroxybenzalidene)4-bromoaniline

    Science.gov (United States)

    Karakaş, Aslı; Ünver, Hüseyin; Elmali, Ayhan

    2008-04-01

    N-(3-Hydroxybenzalidene)4-bromoaniline has been synthesized. Its crystal structure has been determined by X-ray diffraction analysis. To investigate microscopic third-order nonlinear optical (NLO) behavior of the title compound, we have computed both dispersion-free (static) and also frequency-dependent (dynamic) linear polarizabilities ( α) and second hyperpolarizabilities ( γ) at λ = 825-1125 nm and 1050-1600 nm wavelength areas using time-dependent Hartree-Fock (TDHF) method. The one-photon absorption (OPA) characterization has been theoretically obtained by means of configuration interaction (CI) method. The maximum OPA wavelengths are estimated in the UV region to be shorter than 450 nm, showing good optical transparency to the visible light. According to ab-initio calculation results on (hyper)polarizabilities, the synthesized molecule exhibits second hyperpolarizabilities with non-zero values, and it might have microscopic third-order NLO behavior.

  1. Energy Impacts of Nonlinear Behavior of PCM When Applied into Building Envelope: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tabares-Velasco, P. C.

    2012-08-01

    Previous research on phase change materials (PCM) for building applications has been done for several decades resulting in plenty of literature on PCM properties, temperature, and peak reduction potential. Thus, PCMs are a potential technology to reduce peak loads and HVAC energy consumption in buildings. There are few building energy simulation programs that have PCM modeling features, and even fewer have been validated. Additionally, there is no previous research that indicates the level of accuracy when simulating PCM from a building energy simulation perspective. This study analyzes the effects a nonlinear enthalpy profile has on thermal performance and expected energy benefits for PCM-enhanced insulation.

  2. Nonlinear Behavior of Single Piles in Jacket Type Offshore Platforms Using Incremental Dynamic Analysis

    Directory of Open Access Journals (Sweden)

    Mohammad A. Assareh

    2008-01-01

    Full Text Available The operation for offshore oil has become an important issue in the recent years. Offshore platforms are some of those structures which are built to withstand environmental and accidental loads during oil exploitation operation. One of the most usual types of these platforms is the Jacket Type Offshore Platform (JTOP which can be divided into three important parts, which are Deck, Jacket and piles. In order to increase the safety, particular attention should be paid to earthquake excitations which are directly applied to the piles of these structures. Nonlinearity in piles and buckling of the struts are important issues which have to be considered by the designers of offshore platforms. The case of nonlinearity in piles and failure capture in these members has not effectively been covered by researchers. Incremental Dynamic Analysis (IDA is a powerful tool to assess the capacity of a structure upon seismic loads. In this paper incremental dynamic analysis has been implemented on single piles considering soil-pile interactions and free field site response. The use of nonlinear materials and lateral load resisting elements in the incremental dynamic analysis done in this paper has made it possible to get promising insights for incorporation of appropriate limit states and applications of performance based engineering. Special Engineering Demand Parameters (EDP and Intensity Measures (IM have been introduced for the single pile dynamic analysis in jacket type offshore platforms.

  3. Third-Order Nonlinear Optical Behavior of Novel Polythiophene Derivatives Functionalized with Disperse Red 19 Chromophore

    Directory of Open Access Journals (Sweden)

    Marilú Chávez-Castillo

    2015-01-01

    Full Text Available Two copolymers of 3-alkylthiophene (alkyl = hexyl, octyl and a thiophene functionalized with disperse red 19 (TDR19 as chromophore side chain were synthesized by oxidative polymerization. The synthetic procedure was easy to perform, cost-effective, and highly versatile. The molecular structure, molecular weight distribution, film morphology, and optical and thermal properties of these polythiophene derivatives were determined by NMR, FT-IR, UV-Vis GPC, DSC-TGA, and AFM. The third-order nonlinear optical response of these materials was performed with nanosecond and femtosecond laser pulses by using the third-harmonic generation (THG and Z-scan techniques at infrared wavelengths of 1300 and 800 nm, respectively. From these experiments it was observed that although the TRD19 incorporation into the side chain of the copolymers was lower than 5%, it was sufficient to increase their nonlinear response in solid state. For instance, the third-order nonlinear electric susceptibility (χ3 of solid thin films made of these copolymers exhibited an increment of nearly 60% when TDR19 incorporation increased from 3% to 5%. In solution, the copolymers exhibited similar two-photon absorption cross sections σ2PA with a maximum value of 8545 GM and 233 GM (1 GM = 10−50 cm4 s per repeated monomeric unit.

  4. Analysis of the Nonlinear Static and Dynamic Behavior of Offshore Structures

    KAUST Repository

    Alfosail, Feras

    2015-07-01

    Understanding static and dynamic nonlinear behavior of pipes and risers is crucial for the design aspects in offshore engineering fields. In this work, we examine two nonlinear problems in offshore engineering field: vortex Induced vibration of straight horizontal pipes, and boundary layer static solution of inclined risers. In the first study, we analyze the effect of the internal velocity of straight horizontal pipe and obtain the vortex induced vibration forces via coupling the pipe equation of motion with the recently modified Van Der Pol oscillator governing the lift coefficient. Our numerical results are obtained for two different pipe configurations: hinged-hinged, and clamped- clamped. The results show that the internal velocity reduces the vibration and the oscillation amplitudes. Also, it is shown that the clamped-clamped pipe configuration offers a wider range of internal velocities before buckling instability occurs. The results also demonstrate the effect of the end condition on the amplitudes of vibration. In the second study, we develop a boundary layer perturbation static solution to govern and simulate the static behavior of inclined risers. In the boundary layer analysis, we take in consideration the effects of the axial stretch, applied tension, and internal velocity. Our numerical simulation results show good agreement with the exact solutions for special cases. In addition, our developed method overcomes the mathematical and numerical limitations of the previous methods used before.

  5. Nonlinear magnetic resonance behavior and reversible adsorbed gas effects from trace ferromagnestism in Y-zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Iton, L.E.

    1977-01-01

    Unusual spin resonance observations made on a sample of rare earth ion-exchanged Y-zeolite have been attributed to the presence of a ferromagnetic impurity, and are qualitatively explained in terms of existing theories on nonlinear behavior in ferromagnetic resonance at high power. The effects included foldover and bistable response below 136 K, due to classical, anisotropy-based nonlinearity; above 136 K, apparent subsidiary absorption--the Suhl instability driven by coupling of low-frequency spin wave modes to the main resonance--predominated. Modification of the surface anisotropy is suggested to account for the complete suppression of the low-temperature effects when the zeolity sample was cooled in air, the high-temperature effects persisting after this cooling but with a loss of orientational anisotropy. Brief room temperature evacuation of the sample was sufficient to regenerate the original effects. Some details of the resonance behavior are very similar to recently published observations from magnetite impurities; those were there attributed to field-induced transitions. The limitations under which a field-dependent Verwey transition could be used to rationalize such observations have been schematically expounded, and the importance of the microwave field again appears to be the dominating factor.

  6. Nonlinear dynamic behaviors of permanent magnet synchronous motors in electric vehicles caused by unbalanced magnetic pull

    Science.gov (United States)

    Xiang, Changle; Liu, Feng; Liu, Hui; Han, Lijin; Zhang, Xun

    2016-06-01

    Unbalanced magnetic pull (UMP) plays a key role in nonlinear dynamic behaviors of permanent magnet synchronous motors (PMSM) in electric vehicles. Based on Jeffcott rotor model, the stiffness characteristics of the rotor system of the PMSM are analyzed and the nonlinear dynamic behaviors influenced by UMP are investigated. In free vibration study, eigenvalue-based stability analysis for multiple equilibrium points is performed which offers an insight in system stiffness. Amplitude modulation effects are discovered of which the mechanism is explained and the period of modulating signal is carried out by phase analysis and averaging method. The analysis indicates that the effects are caused by the interaction of the initial phases of forward and backward whirling motions. In forced vibration study, considering dynamic eccentricity, frequency characteristics revealing softening type are obtained by harmonic balance method, and the stability of periodic solution is investigated by Routh-Hurwitz criterion. The frequency characteristics analysis indicates that the response amplitude is limited in the range between the amplitudes of the two kinds of equilibrium points. In the vicinity of the continuum of equilibrium points, the system hardly provides resistance to bending, and hence external disturbances easily cause loss of stability. It is useful for the design of the PMSM with high stability and low vibration and acoustic noise.

  7. A study on nonlinear behavior of reactor containment structures during ultimate accident condition(I)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Hoon; Kim, Young Jin; Park, Joo Yeon [Youngdong Univ., Yeongdong (Korea, Republic of)] (and others)

    2003-03-15

    In this study, the following scope and contents are established for first year's study of determining ultimate pressure capacity of CANDU-type reactor containment. State-of-arts on the prediction of the ultimate pressure capacity of prestressed concrete reactor containment. Comparative study on structural characteristics and analysis model of CANDU-type reactor containment. State-of-arts on evaluation method of the ultimate pressure capacity of prestressed concrete reactor containment. Enhancement of evaluation method of the ultimate pressure capacity for PWR containment structure. In order to determine a realistic lower bound of a typical reactor containment structural capacity for internal pressure, modelling techniques and analytical investigation to predict its non-linear behavior up to ultimate capacity are required. Especially, the in-depth evaluation of modeling technique and analysis procedure for determining ultimate pressure capacity of CANDU-type reactor containment is required. Therefore, modelling techniques and analytical investigation to predict its non-linear behavior up to ultimate pressure capacity of CANDU-type reactor containment for internal pressure will be suggested in this study.

  8. Non-linear states of a positive or negative refraction index material in a cavity with feedback

    Science.gov (United States)

    Mártin, D. A.; Hoyuelos, M.

    2010-06-01

    We study a system composed by a cavity with plane mirrors containing a positive or negative refraction index material with third order effective electric and magnetic non-linearities. The aim of the work is to present a general picture of possible non-linear states in terms of the relevant parameters of the system. The parameters are the ones that appear in a reduced description that has the form of the Lugiato-Lefever equation. This equation is obtained from two coupled non-linear Schrödinger equations for the electric and magnetic field amplitudes.

  9. Surveying FIFA Instructors' Behavioral Intention toward the Multimedia Teaching Materials

    Science.gov (United States)

    Armenteros, M.; Liaw, Shu-Sheng; Fernandez, M.; Diaz, R. Flores; Sanchez, R. Arteaga

    2013-01-01

    Instruction delivered via multimedia applications is changing the way elite football refereeing instructors teach the Laws of the Game. Although e-learning applications are popular, there is minimal research on instructors' attitudes toward these teaching materials. The purpose of this research is to explore instructors' behavioral intentions…

  10. Surveying FIFA Instructors' Behavioral Intention toward the Multimedia Teaching Materials

    Science.gov (United States)

    Armenteros, M.; Liaw, Shu-Sheng; Fernandez, M.; Diaz, R. Flores; Sanchez, R. Arteaga

    2013-01-01

    Instruction delivered via multimedia applications is changing the way elite football refereeing instructors teach the Laws of the Game. Although e-learning applications are popular, there is minimal research on instructors' attitudes toward these teaching materials. The purpose of this research is to explore instructors' behavioral intentions…

  11. Polarimetric scattering behavior of materials at terahertz frequencies

    Science.gov (United States)

    DiGiovanni, David Anthony

    Terahertz spectroscopic techniques have long been used to characterize the electromagnetic behavior of materials for use in radar, astronomy, and remote sensing applications. Spectroscopic information is valuable, but additional information about materials is present in the polarization of the scattered radiation. This thesis has investigated the polarimetric scattering behavior of various rough dielectric and metallic materials from 100 GHz to 1.55 THz. Common building materials and terrain, such as sand, gravel, soil, concrete, and roofing shingles, were studied. In order to obtain a better understanding of basic rough surface scattering phenomenology in this region of the spectrum, roughened metal and plastic samples were studied as well. The scattering behavior of these materials was studied as a function of incident angle, roughness, frequency, and polarization. Theoretical scattering models were used to compare measured results to theoretical predictions. Good agreement was observed between scattering measurements and theoretical predictions based on the small perturbation theory for the roughened metal surfaces. However, a substantial disagreement was observed for the rough dielectric surfaces and is discussed.

  12. Dependence of triboelectric charging behavior on material microstructure

    Science.gov (United States)

    Wang, Andrew E.; Gil, Phwey S.; Holonga, Moses; Yavuz, Zelal; Baytekin, H. Tarik; Sankaran, R. Mohan; Lacks, Daniel J.

    2017-08-01

    We demonstrate that differences in the microstructure of chemically identical materials can lead to distinct triboelectric charging behavior. Contact charging experiments are carried out between strained and unstrained polytetrafluoroethylene samples. Whereas charge transfer is random between samples of identical strain, when one of the samples is strained, systematic charge transfer occurs. No significant changes in the molecular-level structure of the polymer are observed by XRD and micro-Raman spectroscopy after deformation. However, the strained surfaces are found to exhibit void and craze formation spanning the nano- to micrometer length scales by molecular dynamics simulations, SEM, UV-vis spectroscopy, and naked-eye observations. This suggests that material microstructure (voids and crazes) can govern the triboelectric charging behavior of materials.

  13. Perturbations of flows of incompressible nonlinearly viscous and viscoplastic fluids caused by variations in material functions

    Science.gov (United States)

    Georgievskii, D. V.

    2007-06-01

    Material functions are necessary element of the constitutive relations determining any model of continuum. These functions can be defined as a collection of objects from which the operator of constitutive relations can be reconstructed completely. The material functions are found in test experiments and show the differences between a given medium and other media in the framework of the same model [1]. The "test experiment theory" is an important part of modern experimental mechanics. Just as in any experiment, from determining the viscosity coefficient by using the rotational viscosimeters to constructing the yield surface by using machines combined loading, the material functions are determined with an unavoidable error. For example, experimenters know that, in experiments with arbitrary accuracy, the moduli of elasticity can only be measured with an unimprovable tolerance of about 7%. Starting already from [2], the investigators' attention has been repeatedly drawn to the fact that it is necessary to take into account this tolerance in determining the material constants, functions, and functionals in problems of mechanics and especially in analyzing the stability of deformation processes. Mathematically, this means that problems of stability under perturbations of the initial data, external constantly acting forces, domain boundaries, etc. should be supplemented with the assumption that the material functions have unknown perturbations of a certain class [3]. The variations of material functions in the framework of the linearized stability theory were considered in [2, 4, 5]. In what follows, we study isotropic tensor functions in the most general case of scalar and tensor nonlinearity. These functions are assigned the meaning of constitutive relations between the stress and strain rate tensors in continuum. These constitutive relations contain scalar material functions of invariants on which, as follows from the above, some variations proportional to a small

  14. Efficient split field FDTD analysis of third-order nonlinear materials in two-dimensionally periodic media

    Science.gov (United States)

    Francés, Jorge; Bleda, Sergio; Bej, Subhajit; Tervo, Jani; Navarro-Fuster, Víctor; Fenoll, Sandra; Martínez-Gaurdiola, Francisco J.; Neipp, Cristian

    2016-04-01

    In this work the split-field finite-difference time-domain method (SF-FDTD) has been extended for the analysis of two-dimensionally periodic structures with third-order nonlinear media. The accuracy of the method is verified by comparisons with the nonlinear Fourier Modal Method (FMM). Once the formalism has been validated, examples of one- and two-dimensional nonlinear gratings are analysed. Regarding the 2D case, the shifting in resonant waveguides is corroborated. Here, not only the scalar Kerr effect is considered, the tensorial nature of the third-order nonlinear susceptibility is also included. The consideration of nonlinear materials in this kind of devices permits to design tunable devices such as variable band filters. However, the third-order nonlinear susceptibility is usually small and high intensities are needed in order to trigger the nonlinear effect. Here, a one-dimensional CBG is analysed in both linear and nonlinear regime and the shifting of the resonance peaks in both TE and TM are achieved numerically. The application of a numerical method based on the finite- difference time-domain method permits to analyse this issue from the time domain, thus bistability curves are also computed by means of the numerical method. These curves show how the nonlinear effect modifies the properties of the structure as a function of variable input pump field. When taking the nonlinear behaviour into account, the estimation of the electric field components becomes more challenging. In this paper, we present a set of acceleration strategies based on parallel software and hardware solutions.

  15. Assessment of Effects of a Delay Block and a Nonlinear Block in Systems with Chaotic Behavior Using Lyapunov Exponents

    Directory of Open Access Journals (Sweden)

    Pablo César Rodríguez Gómez

    2017-05-01

    Full Text Available Context: Because feedback systems are very common and widely used, studies of the structural characteristics under which chaotic behavior is generated have been developed. These can be separated into a nonlinear system and a linear system at least of the third order. Methods such as the descriptive function have been used for analysis. Method: A feedback system is proposed comprising a linear system, a nonlinear system and a delay block, in order to assess his behavior using Lyapunov exponents. It is evaluated with three different linear systems, different delay values and different values for parameters of nonlinear characteristic, aiming to reach chaotic behavior. Results: One hundred experiments were carried out for each of the three linear systems, by changing the value of some parameters, assessing their influence on the dynamics of the system. Contour plots that relate these parameters to the Largest Lyapunov exponent were obtained and analyzed. Conclusions: In spite non-linearity is a condition for the existence of chaos, this does not imply that any nonlinear characteristic generates a chaotic system, it is reflected by the contour plots showing the transitions between chaotic and no chaotic behavior of the feedback system. Language: English

  16. Numerical estimation of 3D mechanical forces exerted by cells on non-linear materials.

    Science.gov (United States)

    Palacio, J; Jorge-Peñas, A; Muñoz-Barrutia, A; Ortiz-de-Solorzano, C; de Juan-Pardo, E; García-Aznar, J M

    2013-01-04

    The exchange of physical forces in both cell-cell and cell-matrix interactions play a significant role in a variety of physiological and pathological processes, such as cell migration, cancer metastasis, inflammation and wound healing. Therefore, great interest exists in accurately quantifying the forces that cells exert on their substrate during migration. Traction Force Microscopy (TFM) is the most widely used method for measuring cell traction forces. Several mathematical techniques have been developed to estimate forces from TFM experiments. However, certain simplifications are commonly assumed, such as linear elasticity of the materials and/or free geometries, which in some cases may lead to inaccurate results. Here, cellular forces are numerically estimated by solving a minimization problem that combines multiple non-linear FEM solutions. Our simulations, free from constraints on the geometrical and the mechanical conditions, show that forces are predicted with higher accuracy than when using the standard approaches.

  17. New approaches for the fabrication of photonic structures of nonlinear optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Carvajal, J.J., E-mail: joanjosep.carvajal@urv.ca [Fisica i Cristal lografia de Materials i Nanomaterials (FiCMA-FiCNA), Univ. Rovira i Virgili (URV), Campus Sescelades, Marcel li Domingo, s/n, E-43007 Tarragona (Spain); Pena, A.; Kumar, R.; Pujol, M.C.; Mateos, X.; Aguilo, M. [Fisica i Cristal lografia de Materials i Nanomaterials (FiCMA-FiCNA), Univ. Rovira i Virgili (URV), Campus Sescelades, Marcel li Domingo, s/n, E-43007 Tarragona (Spain); Diaz, F., E-mail: f.diaz@urv.ca [Fisica i Cristal lografia de Materials i Nanomaterials (FiCMA-FiCNA), Univ. Rovira i Virgili (URV), Campus Sescelades, Marcel li Domingo, s/n, E-43007 Tarragona (Spain); Vazquez de Aldana, J.R.; Mendez, C.; Moreno, P.; Roso, L. [Servicio Laser, Univ. Salamanca, E-37008 Salamanca (Spain); Trifonov, T.; Rodriguez, A.; Alcubilla, R. [Dept. Enginyeria Electronica, Univ. Politecnica de Catalunya, E-08034 Barcelona (Spain); Kral, Z.; Ferre-Borrull, J.; Pallares, J.; Marsal, L.F. [Dept. d' Enginyeria Electronica, Univ. Rovira i Virgili (URV), E-43007 Tarragona (Spain); Di Finizio, S.; Macovez, R. [ICFO-Institut de Ciencies Fotoniques, E-08860 Castelldefels (Spain)

    2009-12-15

    We revisited two different strategies to fabricate 1D photonic crystals of nonlinear optical dielectric materials based on ultrafast laser ablation of the surface of an RbTiOPO{sub 4} crystal, and selective etching of ferroelectric domains of the surface of a periodically poled LiNbO{sub 4} crystal. We evaluated their behaviour as Bragg diffraction gratings. We also presented the recent advances we developed in a new procedure of fabrication of 2D and 3D photonic crystals of KTiOPO{sub 4} (KTP) grown on the surface of a KTP substrate by liquid phase epitaxial means within the pores of a silicon macroporous template. Optical, structural, morphological, and compositional characterization for the photonic crystals produced through this technique are presented.

  18. Growth and characterization of proficient second order nonlinear optical material: L-asparaginium picrate (LASP)

    Science.gov (United States)

    Saravanan, M.; Senthil, A.; Rajasekar, S. Abraham

    2016-09-01

    Good optical quality, potential second order nonlinear optical crystal L-asparaginium picrate (LASP) was grown by the slow cooling method. The solubility and metastable zone width of LASP specimen was studied. The LASP crystal belongs to monoclinic crystal system with noncentrosymmetric space group P21. UV-Visible-NIR transmittance spectrum determines the optical band gap of LASP. Excellence of the grown crystal is ascertained by the etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of LASP sample was investigated at different temperatures. The piezoelectric nature, Photoconductive nature and the relative Second Harmonic Generation (for various particle sizes) of the material were also studied. Birefringence and ocular (optical) homogeneity of the crystal were assessed using modified channel spectrum method.

  19. First Example of Nonlinear Optical Materials Based on Nanoconjugates of Sandwich Phthalocyanines with Quantum Dots.

    Science.gov (United States)

    Oluwole, David O; Yagodin, Alexey V; Mkhize, Nhlakanipho C; Sekhosana, Kutloano E; Martynov, Alexander G; Gorbunova, Yulia G; Tsivadze, Aslan Yu; Nyokong, Tebello

    2017-02-24

    We report original, selective, and efficient approaches to novel nonlinear optical (NLO) materials, namely homoleptic double- and triple-decker europium(III) complexes 2 and 3 with the A3 B-type phthalocyanine ligand (2,3-bis[2'-(2''-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-n-butoxyphthalocyanine 1) bearing two anchoring diethyleneglycol chains terminated with OH groups. Their covalently linked nanoconjugates with mercaptosuccinic acid-capped ternary CdSeTe/CdTeS/ZnSeS quantum dots are prepared in the presence of an ethyl(dimethylaminopropyl)carbodiimide activating agent. Optical limiting (OL) properties of the obtained low-symmetry complexes and their conjugates with quantum dots (QDs) are measured for the first time by the open-aperture Z-scan technique (532 nm laser and pulse rate of 10 ns). For comparison, symmetrical double- and triple-decker Eu(III) octa-n-butoxyphthalocyaninates 5 and 6 and their mixtures with trioctylphosphine oxide-capped QDs are also synthesized and studied. It is revealed that both lowering of molecular symmetry and expansion of the π-electron system upon moving from double- to triple-decker complexes significantly improves the OL characteristics, making the low-symmetry triple-decker complex 3 the most efficient optical limiter in the studied family of sandwich complexes, affording 50 % lowering of light transmittance below 0.5 J cm(-2) input fluence. Conjugation (both covalent and noncovalent) with QDs affords further enhancement of the OL properties of both double- and triple-decker complexes. Altogether, the obtained results contribute to the development of novel nonlinear optical materials for future nanoelectronic and optical device applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Nonlinear Dynamic Behavior of a Flexible Structure to Combined External Acoustic and Parametric Excitation

    Directory of Open Access Journals (Sweden)

    Paulo S. Varoto

    2006-01-01

    Full Text Available Flexible structures are frequently subjected to multiple inputs when in the field environment. The accurate determination of the system dynamic response to multiple inputs depends on how much information is available from the excitation sources that act on the system under study. Detailed information include, but are not restricted to appropriate characterization of the excitation sources in terms of their variation in time and in space for the case of distributed loads. Another important aspect related to the excitation sources is how inputs of different nature contribute to the measured dynamic response. A particular and important driving mechanism that can occur in practical situations is the parametric resonance. Another important input that occurs frequently in practice is related to acoustic pressure distributions that is a distributed type of loading. In this paper, detailed theoretical and experimental investigations on the dynamic response of a flexible cantilever beam carrying a tip mass to simultaneously applied external acoustic and parametric excitation signals have been performed. A mathematical model for transverse nonlinear vibration is obtained by employing Lagrange’s equations where important nonlinear effects such as the beam’s curvature and quadratic viscous damping are accounted for in the equation of motion. The beam is driven by two excitation sources, a sinusoidal motion applied to the beam’s fixed end and parallel to its longitudinal axis and a distributed sinusoidal acoustic load applied orthogonally to the beam’s longitudinal axis. The major goal here is to investigate theoretically as well as experimentally the dynamic behavior of the beam-lumped mass system under the action of these two excitation sources. Results from an extensive experimental work show how these two excitation sources interacts for various testing conditions. These experimental results are validated through numerically simulated results

  1. Organized chromophoric assemblies for nonlinear optical materials: towards (sub)wavelength scale architectures.

    Science.gov (United States)

    Xu, Jialiang; Semin, Sergey; Rasing, Theo; Rowan, Alan E

    2015-03-01

    Photonic circuits are expected to greatly contribute to the next generation of integrated chips, as electronic integrated circuits become confronted with bottlenecks such as heat generation and bandwidth limitations. One of the main challenges for the state-of-the-art photonic circuits lies in the development of optical materials with high nonlinear optical (NLO) susceptibilities, in particular in the wavelength and subwavelength dimensions which are compatible with on-chip technologies. In this review, the varied approaches to micro-/nanosized NLO materials based on building blocks of bio- and biomimetic molecules, as well as synthetic D-π-A chromophores, have been categorized as supramolecular self-assemblies, molecular scaffolds, and external force directed assemblies. Such molecular and supramolecular NLO materials have intrinsic advantages, such as structural diversities, high NLO susceptibilities, and clear structure-property relationships. These "bottom-up" fabrication approaches are proposed to be combined with the "top-down" techniques such as lithography, etc., to generate multifunctionality by coupling light and matter on the (sub)wavelength scale. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Crystal growth of an organic non-linear optical material from the vapour phase

    CERN Document Server

    Hou, W

    1999-01-01

    Due to the potential applications of organic non-linear optical materials in the areas of optical processing and communication, the investigation of the crystal growth of new organic NLO materials has been an active field for the last 20 years. For such uses it is necessary to produce single crystals of high quality and perfection, free of strain and defects. When crystals are grown from the solution and the melt, solvent and the decomposition component in the melt can introduce impurities and imperfection to the as-grown crystals. For crystals grown from vapour phase, in the absence of the solvent, this cannot occur and the method promises to yield single crystals of higher quality. Despite this attraction, little attention has been paid to the vapour phase growth of organic NLO crystals. It was with this in mind that the following investigation was carried out. Using Methyl p-hydroxybenzoate (p-MHB), a potential organic NLO material, a comparison investigation was made of its crystal growth from both the va...

  3. Study of novel nonlinear optical material based on Poly(aryl ether ketone) and its application in SHG imaging

    Science.gov (United States)

    Liu, Yi; Liu, Hui; Qin, Guangjiong; Gui, Zhiguo; Yang, Zhimao; Liu, Jialei

    2017-10-01

    Novel nonlinear optical polymer based on poly(aryl ether ketone) was designed and prepared. Such kind of materials showed excellent water solubility and thermal properties, its onset decomposition temperature can reach 314 °C; glass transition temperature can reach 170 °C. Though the nonlinear optical coefficients (d33) is not very large at 1310 nm, just about 13.9 pm/V; such kind of materials show us a low absorption spectral window at red and infrared light area (wavelength longer than 650 nm). Under the laser of 1310 nm, the morphology of the poled films can be detected by second harmonic generation (SHG) scanning microscopy.

  4. The diffusivity-mobility ratio in heavily doped nonlinear optical, optoelectronic and related materials

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, S. [Nano Scale Device Research Laboratory, Centre for Electronics Design and Technology, Indian Institute of Science, Bangalore 560 012 (India); Pahari, S. [Administrative Department, Jadavpur University, Kolkata 700 032 (India); Sarkar, R. [Department of Computer Science and Engineering, West Bengal University of Technology, BF-142, Salt Lake City, Sector-1, Kolkata 700064 (India); Ghosh, S. [Department of Electronics and Telecommunication Engineering, Bengal Engineering and Science University, Howrah 711 103 (India); Ghatak, K.P. [Department of Electronic Science, University of Calcutta, 92, Achryya Prafulla Chandra Road, Kolkata 700 009 (India)], E-mail: kamakhyaghatak@yahoo.co.in

    2008-10-01

    We study the diffusivity-mobility ratio (DMR) in heavily doped nonlinear compounds forming band tails on the basis of a newly formulated electron dispersion law and III-V, ternary and quaternary materials form a special case of our generalized analysis. The complex nature of the energy spectrum and creation of a new forbidden zone is the consequence of anisotropic energy band constants and the interaction of the impurity atoms in the tails with spin-orbit splitting of valence bands for the other compounds. Analytically, the presence of non-removable poles in the dispersion relation of the undoped material creates the complex energy spectrum for the corresponding heavily doped sample. The DMR for the heavily doped II-VI, IV-VI and stressed materials has been studied. It has been found taking n-type CdGeAs{sub 2,}, Cd{sub 3}As{sub 2}, InAs, InSb, Hg{sub 1-x}Cd{sub x}Te, In{sub 1-x}Ga{sub x}As{sub y}P{sub 1-y} lattice matched to InP, CdS, PbTe, PbSnTe, Pb{sub 1-x}Sn{sub x}Se and stressed InSb as examples that the DMR increases with the increasing electron concentration with different numerical values and the nature of variations are totally band structure dependent. An experimental method of determining the DMR in heavily doped materials for arbitrary dispersion relations together with three applications in the area of material science in general has been suggested.

  5. Corrosion and mechanical behavior of materials for coal gasification applications

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1980-05-01

    A state-of-the-art review is presented on the corrosion and mechanical behavior of materials at elevated temperatures in coal-gasification environments. The gas atmosphere in coal-conversion processes are, in general, complex mixtures which contain sulfur-bearing components (H/sub 2/S, SO/sub 2/, and COS) as well as oxidants (CO/sub 2//CO and H/sub 2/O/H/sub 2/). The information developed over the last five years clearly shows sulfidation to be the major mode of material degradation in these environments. The corrosion behavior of structural materials in complex gas environments is examined to evaluate the interrelationships between gas chemistry, alloy chemistry, temperature, and pressure. Thermodynamic aspects of high-temperature corrosion processes that pertain to coal conversion are discussed, and kinetic data are used to compare the behavior of different commercial materials of interest. The influence of complex gas environments on the mechanical properties such as tensile, stress-rupture, and impact on selected alloys is presented. The data have been analyzed, wherever possible, to examine the role of environment on the property variation. The results from ongoing programs on char effects on corrosion and on alloy protection via coatings, cladding, and weld overlay are presented. Areas of additional research with particular emphasis on the development of a better understanding of corrosion processes in complex environments and on alloy design for improved corrosion resistance are discussed. 54 references, 65 figures, 24 tables.

  6. Nonlinear dynamic behavior of rubbing rotor under interaction between bending and torsional vibrations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The nonlinear dynamic behavior of a rubbing rotor system was studied with a mathematical model established with the eccentricity and interaction between bending and torsional vibrations taken into consideration.The nonlinear vibrational response of a rubbing rotor was analyzed using numerical integral,spectroscopic analysis and Poince mapping method,which made it possible to have better understanding of the vibrational characteristics of partial rubbing and complete circular rubbing rotors.The numerical results reveal the response of torsional vibration mainly takes a form of suporchronous motion,and its frequency decreases as the rotational speed increases when partial rubbing occurs,and the response of torsional vibration is synchronous when complete circular rubbing occurs.The comparison of the dynamics of rubbing rotors with and without the interaction between bending and torsional vibrations shows the interaction between bending and torsional vibrations advances the rotational speed,at which the response of bending vibration changes from a synchronous motion into a quasi-periodic motion,and the interaction between bending and torsional vibrations reduces stability of the rubbing rotor.

  7. Thermofluid Behavior of Nonlinear Thermocapillary Solutions in Flow Boiling through Mini⁄Micro Channels

    Science.gov (United States)

    Ono, Naoki; Yoshida, Takahiro; Kaneko, Takahiro; Nishiguchi, Shotaro; Shoji, Masahiro

    The temperature dependency of surface tension of aqueous solutions of some alcohol such as butanol behaves in a nonlinear manner. Namely, the value of surface tension tends to increase, when the solution is heated beyond a temperature. This type of solution is named “nonlinear thermocapillary solution” here. The direction of thermocapillary force in liquid film of the solution on a heated surface acts in the same direction to that of the solutocapillary force. This characteristic will be more marked in small scale systems such as mini⁄micro channels. In this study the liquid behavior of the solution in flow boiling experiments with mini⁄micro tubes was investigated. Butanol aqueous solutions were adopted as test fluids. Pure water and ethanol aqueous solution were also used for comparison. The aim of the study is to observe the liquid motion and to investigate temperature fluctuation in mini⁄micro channels with inner diameter of 1 mm and 0.42 mm. The surface temperature of the tube was measured by using fine K-type thermocouples at the surface of the tubes and the liquid motion was observed by CCD camera system.

  8. Production behavior of irradiation defects in solid breeder materials

    Energy Technology Data Exchange (ETDEWEB)

    Moriyama, Hirotake; Moritani, Kimikazu [Kyoto Univ. (Japan)

    1998-03-01

    The irradiation effects in solid breeder materials are important for the performance assessment of fusion reactor blanket systems. For a clearer understanding of such effects, we have studied the production behavior of irradiation defects in some lithium ceramics by an in-situ luminescence measurement technique under ion beam irradiation. The luminescence spectra were measured at different temperatures, and the temperature-transient behaviors of luminescence intensity were also measured. The production mechanisms of irradiation defects were discussed on the basis of the observations. (author)

  9. Nonlinear Behaviors of Tail Dependence and Cross-Correlation of Financial Time Series Model

    Directory of Open Access Journals (Sweden)

    Wei Deng

    2014-01-01

    Full Text Available Nonlinear behaviors of tail dependence and cross-correlation of financial time series are reproduced and investigated by stochastic voter dynamic system. The voter process is a continuous-time Markov process and is one of the interacting dynamic systems. The tail dependence of return time series for pairs of Chinese stock markets and the proposed financial models is studied by copula analysis, in an attempt to detect and illustrate the existence of relevant correlation relationships. Further, the multifractality of cross-correlations for return series is studied by multifractal detrended cross-correlation analysis, which indicates the analogous cross-correlations and some fractal characters for both actual data and simulative data and provides an intuitive evidence for market inefficiency.

  10. Large time behavior for solutions of nonlinear parabolic problems with sign-changing measure data

    Directory of Open Access Journals (Sweden)

    Francesco Petitta

    2008-09-01

    Full Text Available Let $Omegasubseteq mathbb{R}^N$ a bounded open set, $Ngeq 2$, and let $p>1$; in this paper we study the asymptotic behavior with respect to the time variable $t$ of the entropy solution of nonlinear parabolic problems whose model is $$displaylines{ u_{t}(x,t-Delta_{p} u(x,t=mu quad hbox{in } Omegaimes(0,infty,cr u(x,0=u_{0}(x quad hbox{in } Omega, }$$ where $u_0 in L^{1}(Omega$, and $muin mathcal{M}_{0}(Q$ is a measure with bounded variation over $Q=Omegaimes(0,infty$ which does not charge the sets of zero $p$-capacity; moreover we consider $mu$ that does not depend on time. In particular, we prove that solutions of such problems converge to stationary solutions.

  11. THE NONLINEAR BEHAVIOR OF INTERFACE BETWEEN TWO-PHASE SHEAR FLOW WITH LARGE DENSITY RATIOS

    Institute of Scientific and Technical Information of China (English)

    DONG Yu-hong

    2006-01-01

    The Navier-Stokes equations for the two-dimensional incompressible flow are used to investigate the effects of the Reynolds number and the Weber number on the behavior of interface between liquid-gas shear flow.In the present study, the density ratios are fixed at approximately 100-103.The interface between the two phases is resolved using the level-set approach.The Reynolds number and the Weber number, based on the gas, are selected as 400-10000 and 40-5000, respectively.In the past, simulations reappeared the amplitude of interface growth predicted by viscous Orr-Sommerfeld linear theory, verifying the applicability and accuracy of the numerical method over a wide range of density and viscosity ratios; now, the simulations show that the nonlinear development of ligament elongated structures and resulted in the subsequent breakup of the heavier fluid into drops.

  12. Nonlinear behavior of saturated porous crust under the influence of internal fluid source

    Science.gov (United States)

    Suetnova, Elena; Cherniavski, Vladimir

    2010-05-01

    We consider the effective stress evolution inside high porosity fault zone as a result of local dehydration due to heating. The rock is assumed to be a two-velocity medium; it consists of a deformable porous matrix (with Maxwell's rheology) and a Newtonian liquid that saturates this matrix. Nonlinear behavior of liquid saturated porous media in gravity filed under the influence of internal fluid source is modeled. The elaborated non-isothermal mathematical model is a thermodynamically consistent and closed model. The original scheme was used for computer simulation; the method implies numerical simulation for effective stress, deformation and flux time- space evolution. Deformation spreading through the saturated porous matrix occurs with pressure distortions. Calculations show that the peculiarity of effective stress evolution is dependent not only upon the volume of supplementary fluids, but upon the viscosity and elastic modules of matrix.

  13. Dynamic behavior of particulate/porous energetic materials

    Science.gov (United States)

    Nesterenko, Vitali F.; Chiu, Po-Hsun; Braithwaite, C. H.; Collins, Adam; Williamson, David Martin; Olney, Karl L.; Benson, David; McKenzie, Francesca

    2012-03-01

    Dynamic behavior of particulate/porous energetic materials in a broad range of dynamic conditions (low velocity impact and explosively driven expansion of rings) is discussed. Samples of these materials were fabricated using Cold Isostatic Pressing and Hot Isostatic Pressing with and without vacuum encapsulation. The current interest in these materials is due to the combination of their high strength and output of energy under critical conditions of mechanical deformation. They may exhibit high compressive and tensile strength with the ability to undergo bulk distributed fracture resulting in small size reactive fragments. The mechanical properties of these materials and the fragment sizes produced by fracturing are highly sensitive to mesostructure. For example, the dynamic strength of Al-W composites with fine W particles is significantly larger than the strength of composites with coarse W particles at the same porosity. The morphology of W inclusions had a strong effect on the dynamic strength and fracture pattern. Experimental results are compared with numerical data.

  14. Continuum mechanical and computational aspects of material behavior

    Energy Technology Data Exchange (ETDEWEB)

    Fried, Eliot; Gurtin, Morton E.

    2000-02-10

    The focus of the work is the application of continuum mechanics to materials science, specifically to the macroscopic characterization of material behavior at small length scales. The long-term goals are a continuum-mechanical framework for the study of materials that provides a basis for general theories and leads to boundary-value problems of physical relevance, and computational methods appropriate to these problems supplemented by physically meaningful regularizations to aid in their solution. Specific studies include the following: the development of a theory of polycrystalline plasticity that incorporates free energy associated with lattice mismatch between grains; the development of a theory of geometrically necessary dislocations within the context of finite-strain plasticity; the development of a gradient theory for single-crystal plasticity with geometrically necessary dislocations; simulations of dynamical fracture using a theory that allows for the kinking and branching of cracks; computation of segregation and compaction in flowing granular materials.

  15. Numerical insight into the seismic behavior of eight masonry towers in Northern Italy: FE pushover vs non-linear dynamic analyses

    Energy Technology Data Exchange (ETDEWEB)

    Milani, Gabriele, E-mail: milani@stru.polimi.it, E-mail: gabriele.milani@polimi.it; Valente, Marco [Department of Architecture, Built Environment and Construction Engineering (ABC), Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)

    2015-12-31

    This study presents some FE results regarding the behavior under horizontal loads of eight existing masonry towers located in the North-East of Italy. The towers, albeit unique for geometric and architectural features, show some affinities which justify a comparative analysis, as for instance the location and the similar masonry material. Their structural behavior under horizontal loads is therefore influenced by geometrical issues, such as slenderness, walls thickness, perforations, irregularities, presence of internal vaults, etc., all features which may be responsible for a peculiar output. The geometry of the towers is deduced from both existing available documentation and in-situ surveys. On the basis of such geometrical data, a detailed 3D realistic mesh is conceived, with a point by point characterization of each single geometric element. The FE models are analysed under seismic loads acting along geometric axes of the plan section, both under non-linear static (pushover) and non-linear dynamic excitation assumptions. A damage-plasticity material model exhibiting softening in both tension and compression, already available in the commercial code Abaqus, is used for masonry. Pushover analyses are performed with both G1 and G2 horizontal loads distribution, according to Italian code requirements, along X+/− and Y+/− directions. Non-linear dynamic analyses are performed along both X and Y directions with a real accelerogram scaled to different peak ground accelerations. Some few results are presented in this paper. It is found that the results obtained with pushover analyses reasonably well fit expensive non-linear dynamic simulations, with a slightly less conservative trend.

  16. Critical behavior of nanoemitter radiation in a percolation material

    Energy Technology Data Exchange (ETDEWEB)

    Burlak, G. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas (Mexico)], E-mail: gburlak@uaem.mx; Diaz-de-Anda, A. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas (Mexico); Karlovich, Yu. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Cuernavaca, Mor. Mexico (Mexico); Klimov, A.B. [Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, Guadalajara, Jalisco 44420 (Mexico)

    2009-04-06

    We studied the field radiation of disordered optical nanoemitters incorporated into three-dimensional (3D) spanning cluster in a percolation material. In supercritical state, the field intensity is large enough to produce a dynamic high-density coherent field. The resulting state becomes different for lossless and lossy mediums. For material with small losses the long-term coherence arises in the supercritical area close to the percolation threshold. As a result, the dynamic non-monotonic behavior of the field order parameter raises that allows to reach the optimal field intensity. This effect can allow optimization of the disordered optical nanostructures with incorporated radiating nanoemitters in various applications of information technology.

  17. Theoretical and Experimental Investigation of the Nonlinear Behavior of an Electrostatically Actuated In-Plane MEMS Arch

    KAUST Repository

    Ramini, Abdallah

    2016-05-02

    We present theoretical and experimental investigation of the nonlinear behavior of a clamped-clamped in-plane MEMS arch when excited by a DC electrostatic load superimposed to an AC harmonic load. Experimentally, a case study of in-plane silicon micromachined arch is examined and its mechanical behavior is measured using optical techniques. An algorithm is developed to extract the various parameters, such as the induced axial force and the initial rise, needed to model the behavior of the arch. A softening spring behavior is observed when the excitation is close to the first resonance frequency due to the quadratic nonlinearity coming from the arch geometry and the electrostatic force. Also, a hardening spring behavior is observed when the excitation is close to the third (second symmetric) resonance frequency due to the cubic nonlinearity coming from mid-plane stretching. Dynamic snap-through behavior is also reported for larger range of electric loads. Theoretically, a multi-mode Galerkin reduced order model is utilized to simulate the arch behavior. General agreement is reported among the theoretical and experimental data.

  18. Mechanical behavior of plastic materials for automobile cockpit module

    Science.gov (United States)

    Woo, Changsu.; Park, Hyunsung.; Jo, Jinho.

    2013-12-01

    Engineering plastics are used in instrument panels, interior trims, and other vehicle applications, and the thermo-mechanical behaviors of plastic materials are strongly influenced by many environmental factors such as temperature, sunlight, and rain. As the material properties change, the mechanical parts create unexpected noise. In this study, the dynamic mechanical property changes of plastics used in automobiles are measured to investigate the effect of temperature. Visco-elastic properties such as the glass transition temperature and storage modulus and loss factors under temperature and frequency sweeps were measured. The data results were compared with the original ones before aging to analyze the behavioral changes. It was found that as the temperature increased, the storage modulus decreased and the loss factor increased slightly.

  19. Mixed-Metal Carbonate Fluorides as Deep-Ultraviolet Nonlinear Optical Materials.

    Science.gov (United States)

    Tran, T Thao; Young, Joshua; Rondinelli, James M; Halasyamani, P Shiv

    2017-01-25

    Noncentrosymmetric mixed-metal carbonate fluorides are promising materials for deep-ultraviolet (DUV) nonlinear optical (NLO) applications. We report on the synthesis, characterization, structure-property relationships, and electronic structure calculations on two new DUV NLO materials: KMgCO3F and Cs9Mg6(CO3)8F5. Both materials are noncentrosymmetric (NCS). KMgCO3F crystallizes in the achiral and nonpolar NCS space group P6̅2m, whereas Cs9Mg6(CO3)8F5 is found in the polar space group Pmn21. The compounds have three-dimensional structures built up from corner-shared magnesium oxyfluoride and magnesium oxide octahedra. KMgCO3F (Cs9Mg6(CO3)8F5) exhibits second-order harmonic generation (SHG) at both 1064 and 532 nm incident radiation with efficiencies of 120 (20) × α-SiO2 and 0.33 (0.10) × β-BaB2O4, respectively. In addition, short absorption edges of <200 and 208 nm for KMgCO3F and Cs9Mg6(CO3)8F5, respectively, are observed. We compute the electron localization function and density of states of these two compounds using first-principles density functional theory, and show that the different NLO responses arise from differences in the denticity and alignment of the anionic carbonate units. Finally, an examination of the known SHG active AMCO3F (A = alkali metal, M = alkaline earth metal, Zn, Cd, or Pb) materials indicates that, on average, smaller A cations and larger M cations result in increased SHG efficiencies.

  20. Semi-Analytical Solution for Stresses and Displacements in a Tunnel Excavated in Transversely Isotropic Formation with Non-Linear Behavior

    Science.gov (United States)

    Vu, The Manh; Sulem, Jean; Subrin, Didier; Monin, Nathalie

    2013-03-01

    A semi-analytical solution based on the transfer matrix technique is proposed to analyze the stresses and displacements in a two-dimensional circular opening excavated in transversely isotropic formation with non-linear behavior. A non-isotropic far field can be accounted for and the process of excavation is simulated by progressive reduction of the internal radial stress. A hyperbolic stress-strain law is proposed to take into account the non-linear behavior of the rock. The model contains seven independent parameters corresponding to the five elastic constants of an elastic material with transverse isotropy and to the friction coefficient and cohesion along the parallel joints (weakness planes). This approach is based on the discretization of the space into concentric rings. It requires the establishment of elementary solutions corresponding to the stress and displacement fields inside each ring for given conditions at its boundaries. These solutions, based on complex variable theory, are obtained in the form of infinite series. The appropriate number of terms to be kept for acceptable approximation is discussed. This non-linear model is applied to back analyze the convergence measurements of Saint-Martin-la-Porte access gallery. Short-term and long-term ground parameters are evaluated.

  1. Evaluation of frost damage in cement-based materials by a nonlinear elastic wave technique

    Science.gov (United States)

    Eiras, J. N.; Kundu, T.; Popovics, J. S.; Monzó, J.; Soriano, L.; Payá, J.

    2014-03-01

    Frost resistance of concrete is a major concern in cold regions. RILEM (International union of laboratories and experts in construction materials, systems and structures) recommendations provide two alternatives for evaluating frost damage by nondestructive evaluation methods for concrete like materials. The first method is based on the ultrasonic pulse velocity measurement, while the second alternative technique is based on the resonant vibration test. In this study, we monitor the frost damage in Portland cement mortar samples with water to cement ratio of 0.5 and aggregate to cement ratio of 3. The samples are completely saturated by water and are frozen for 24 hours at -25°C. The frost damage is monitored after 0, 5, 10, 15 and 20 freezing-thawing cycles by nonlinear impact resonance acoustic spectroscopy (NIRAS). The results obtained are compared with those obtained by resonant vibration tests, the second alternative technique recommended by RILEM. The obtained results show that NIRAS is more sensitive to early stages of damage than the standard resonant vibration tests.

  2. Mixed and Penalty Finite Element Models for the Nonlinear Behavior of Biphasic Soft Tissues in Finite Deformation: Part II - Nonlinear Examples.

    Science.gov (United States)

    Almeida, EDGARD S.; Spilker, ROBERT L.

    1998-01-01

    This two-part paper addresses finite element-based computational models for the three-dimensional (3-D) nonlinear analysis of soft hydrated tissues, such as articular cartilage in diarthrodial joints, under physiologically relevant loading conditions. A biphasic continuum description is used to represent the soft tissue as a two-phase mixture of incompressible inviscid fluid and a hyperelastic, transversely isotropic solid. Alternate mixed-penalty and velocity-pressure finite element formulations are used to solve the nonlinear biphasic governing equations, including the effects of strain-dependent permeability and a hyperelastic solid phase under finite deformation. The resulting first-order, nonlinear system of equations is discretized in time using an implicit finite difference scheme, and solved using the Newton-Raphson method. Details of the formulations were presented in Part I [1]. In Part II, the two formulations are used to develop two-dimensional (2-D) quadrilateral and triangular elements and three-dimensional (3-D) hexahedral and tetrahedral elements. Numerical examples, including those representative of soft tissue material testing and simple human joints, are used to validate the formulations and to illustrate their applications. A focus of this work is the comparison of the alternate formulations for nonlinear problems. While it is demonstrated that both formulations produce a range of converging elements, the velocity-pressure formulation is found to be more efficient computationally.

  3. The behavior of steady quasisolitons near the limit cases of third-order nonlinear Schrödinger equation

    DEFF Research Database (Denmark)

    Karpman, V.I.; Shagalov, A.G.; Juul Rasmussen, J.

    2002-01-01

    The behavior of steady quasisoliton solutions to the extended third-order nonlinear Schrodinger (NLS) equation is studied in two cases: (i) when the coefficients in the equation approach the Hirota conditions, and (ii) near the limit of the regular NLS equation. (C) 2002 Published by Elsevier...

  4. RHEOLOGICAL BEHAVIOR OF WOOD AND WOOD BASED MATERIALS

    Directory of Open Access Journals (Sweden)

    Rafael Rodolfo de Melo

    2010-05-01

    Full Text Available The wood, as well as other construction materials, presents changes in this stiffness and strength when submitted to a long time loading. This phenomenon is important in the analyses resistance capacity of structural materials. Mechanically, the wood behaves as aviscous-elastic solid. However, over time, the structural elements submitted to permanent or cyclic loading presents some deformation, which denotes a viscous-elastic behavior. This characteristic is influenced mainly on the intensity and duration of loading. In this study a review of rheological phenomenon is presented, showing up the causes and effects for a better understanding, which is essential for the appropriate and efficient use of the wood and wood composites as structural materials.

  5. Investigation of the nonlinear seismic behavior of knee braced frames using the incremental dynamic analysis method

    Science.gov (United States)

    Sheidaii, Mohammad Reza; TahamouliRoudsari, Mehrzad; Gordini, Mehrdad

    2016-06-01

    In knee braced frames, the braces are attached to the knee element rather than the intersection of beams and columns. This bracing system is widely used and preferred over the other commonly used systems for reasons such as having lateral stiffness while having adequate ductility, damage concentration on the second degree convenience of repairing and replacing of these elements after Earthquake. The lateral stiffness of this system is supplied by the bracing member and the ductility of the frame attached to the knee length is supplied through the bending or shear yield of the knee member. In this paper, the nonlinear seismic behavior of knee braced frame systems has been investigated using incremental dynamic analysis (IDA) and the effects of the number of stories in a building, length and the moment of inertia of the knee member on the seismic behavior, elastic stiffness, ductility and the probability of failure of these systems has been determined. In the incremental dynamic analysis, after plotting the IDA diagrams of the accelerograms, the collapse diagrams in the limit states are determined. These diagrams yield that for a constant knee length with reduced moment of inertia, the probability of collapse in limit states heightens and also for a constant knee moment of inertia with increasing length, the probability of collapse in limit states increases.

  6. Modelling nonlinear behavior of labor force participation rate by STAR: An application for Turkey

    Directory of Open Access Journals (Sweden)

    Sibel Cengiz

    2014-04-01

    Full Text Available The aim of this paper is to contribute to the understanding of the behavior of participation rates in terms of gender differences. We employed smooth autoregressive transition models for the quarterly Turkish labor force participation rates (LFPR data between 2000: Q1 - 2011: Q4 to present an asymmetric participation behavior. The smoothness parameter indicates a gradual transition from low to high regimes. It is higher for female workers compared to the male workers. Participation rates diminish during a recession but they increase smoothly during the periods of expansion. The estimation results of Enders et al. (1998 also verified the asymmetry and nonlinearity in participation rates. During periods of economic expansion, they are higher than the threshold but the low regime indicator function takes the value zero. The results of the paper have economic implications for policy makers. Due to the discouraged worker and added worker effects, LFPR should be observed with the unemployment rates while evaluating the tightness of the labor market.

  7. Analysis and classification of collective behavior using generative modeling and nonlinear manifold learning.

    Science.gov (United States)

    Butail, Sachit; Bollt, Erik M; Porfiri, Maurizio

    2013-11-07

    In this paper, we build a framework for the analysis and classification of collective behavior using methods from generative modeling and nonlinear manifold learning. We represent an animal group with a set of finite-sized particles and vary known features of the group structure and motion via a class of generative models to position each particle on a two-dimensional plane. Particle positions are then mapped onto training images that are processed to emphasize the features of interest and match attainable far-field videos of real animal groups. The training images serve as templates of recognizable patterns of collective behavior and are compactly represented in a low-dimensional space called embedding manifold. Two mappings from the manifold are derived: the manifold-to-image mapping serves to reconstruct new and unseen images of the group and the manifold-to-feature mapping allows frame-by-frame classification of raw video. We validate the combined framework on datasets of growing level of complexity. Specifically, we classify artificial images from the generative model, interacting self-propelled particle model, and raw overhead videos of schooling fish obtained from the literature. © 2013 Elsevier Ltd. All rights reserved.

  8. Mathematical model predicts the elastic behavior of composite materials

    Directory of Open Access Journals (Sweden)

    Zoroastro de Miranda Boari

    2005-03-01

    Full Text Available Several studies have found that the non-uniform distribution of reinforcing elements in a composite material can markedly influence its characteristics of elastic and plastic deformation and that a composite's overall response is influenced by the physical and geometrical properties of its reinforcing phases. The finite element method, Eshelby's method and dislocation mechanisms are usually employed in formulating a composite's constitutive response. This paper discusses a composite material containing SiC particles in an aluminum matrix. The purpose of this study was to find the correlation between a composite material's particle distribution and its resistance, and to come up with a mathematical model to predict the material's elastic behavior. The proposed formulation was applied to establish the thermal stress field in the aluminum-SiC composite resulting from its fabrication process, whereby the mixture is prepared at 600 °C and the composite material is used at room temperature. The analytical results, which are presented as stress probabilities, were obtained from the mathematical model proposed herein. These results were compared with the numerical ones obtained by the FEM method. A comparison of the results of the two methods, analytical and numerical, reveals very similar average thermal stress values. It is also shown that Maxwell-Boltzmann's distribution law can be applied to identify the correlation between the material's particle distribution and its resistance, using Eshelby's thermal stresses.

  9. Discrete Element study of granular material - Bumpy wall interface behavior

    Science.gov (United States)

    El Cheikh, Khadija; Rémond, Sébastien; Pizette, Patrick; Vanhove, Yannick; Djelal, Chafika

    2016-09-01

    This paper presents a DEM study of a confined granular material sheared between two parallel bumpy walls. The granular material consists of packed dry spherical particles. The bumpiness is modeled by spheres of a given diameter glued on horizontal planes. Different bumpy surfaces are modeled by varying diameter or concentration of glued spheres. The material is sheared by moving the two bumpy walls at fixed velocity. During shear, the confining pressure applied on each bumpy wall is controlled. The effect of wall bumpiness on the effective friction coefficient and on the granular material behavior at the bumpy walls is reported for various shearing conditions. For given bumpiness and confining pressure that we have studied, it is found that the shear velocity does not affect the shear stress. However, the effective friction coefficient and the behavior of the granular material depend on the bumpiness. When the diameter of the glued spheres is larger than about the average grains diameter of the medium, the latter is uniformly sheared and the effective friction coefficient remains constant. For smaller diameters of the glued spheres, the effective friction coefficient increases with the diameter of glued spheres. The influence of glued spheres concentration is significant only for small glued spheres diameters, typically half of average particle diameter of the granular material. In this case, increasing the concentration of glued spheres leads to a decrease in effective friction coefficient and to shear localization at the interface. For different diameters and concentrations of glued spheres, we show that the effect of bumpiness on the effective friction coefficient can be characterized by the depth of interlocking.

  10. Solution behaviors in coupled Schrödinger equations with full-modulated nonlinearities

    Science.gov (United States)

    Pınar, Zehra; Deliktaş, Ekin

    2017-02-01

    The nonlinear partial differential equations have an important role in real life problems. To obtain the exact solutions of the nonlinear partial differential equations, a number of approximate methods are known in the literature. In this work, a time- space modulated nonlinearities of coupled Schrödinger equations are considered. We provide a large class of Jacobi-elliptic solutions via the auxiliary equation method with sixth order nonlinearity and the Chebyshev approximation.

  11. The Approximate Analysis of Nonlinear Behavior of Structure under Harmonic Loading

    DEFF Research Database (Denmark)

    Bayat, M.; Shahidi, M.; Barari, Amin;

    2010-01-01

    to the scientists in the field. Studying on nonlinear dynamics highlights the fact that essentially all dynamic systems encountered in the real world are nonlinear, meaning that their description as differential equations contains nonlinear terms. Such nonlinearities appear in different ways, such as through...... analytically. In the end, the obtained results are compared with numerical ones and shown in graphs and in tables; analytical solutions are in good agreement with those of the numerical method....

  12. Extreme Spectroscopy: In situ nuclear materials behavior from optical data

    Energy Technology Data Exchange (ETDEWEB)

    Guimbretiere, G.; Canizares, A.; Raimboux, N.; Omnee, R.; Duval, F.; Ammar, M.R.; Simon, P. [CNRS - UPR3079 CEMHTI, Universite d' Orleans, 45071Orleans cedex 2 (France); Desgranges, L.; Mohun, R. [CEA, DEN, DEC, F-13108 Saint-Paul-Lez-Durance (France); Jegou, C.; Magnin, M. [CEA/DTCD/SECM/LMPA, Marcoule 30207 Bagnols Sur Ceze (France); Clavier, N.; Dacheux, N. [ICSM-UMR5257 CEA/CNRS/UM2/ENSCM, Marcoule, BP17171, 30207 Bagnols sur Ceze (France)

    2015-07-01

    In the nuclear industry, materials are regularly exposed to high temperature or/and irradiation and a better knowledge and understanding of their behavior under such extreme conditions is a key-point for improvements and further developments. Nowadays, Raman spectroscopy begins to be well known as a promising technique in the post mortem and remote characterization of nuclear materials exposed to extreme conditions. On this topic, at ANIMMA 2013 conference, we have presented some results about its implementation in the study of model or real nuclear fuel. However, the strength of Raman spectroscopy as in situ characterization tool is mainly its ability to be implemented remotely through optical fibers. Aware of this, implementation of other optical techniques can be considered in order to gain information not only on the structural dynamics of materials but also on the electronic charge carrier populations. In this paper, we propose to present our last advances in Raman characterization of nuclear materials and enlarge to the in situ use of complementary optical spectroscopies. Emphasis will be made on the information that can be gained to the behavior of the model fuel depleted UO{sub 2} under extreme conditions of high temperature and ionic irradiation: - In Situ Raman identification of the radiolysis alteration products of UO{sub 2} in contact with water under ionic irradiation. - In Situ Raman recording of the damaged dynamic of UO{sub 2} under inert atmosphere. - In Situ Raman and photo-luminescence study of virgin and damaged UO2 at high temperature. - In Situ study of electronic charge carriers' behavior in U{sub x}Th{sub 1-x}O{sub 2} solid solutions by mean of Iono- and Thermo- luminescence under and post- ionic irradiation. (authors)

  13. MODELING OF NONLINEAR CYCLIC LOAD BEHAVIOR OF I-SHAPED COMPOSITE STEEL-CONCRETE SHEAR WALLS OF NUCLEAR POWER PLANTS

    Directory of Open Access Journals (Sweden)

    AHMER ALI

    2013-02-01

    Full Text Available In recent years steel-concrete composite shear walls have been widely used in enormous high-rise buildings. Due to high strength and ductility, enhanced stiffness, stable cycle characteristics and large energy absorption, such walls can be adopted in the auxiliary building; surrounding the reactor containment structure of nuclear power plants to resist lateral forces induced by heavy winds and severe earthquakes. This paper demonstrates a set of nonlinear numerical studies on I-shaped composite steel-concrete shear walls of the nuclear power plants subjected to reverse cyclic loading. A three-dimensional finite element model is developed using ABAQUS by emphasizing on constitutive material modeling and element type to represent the real physical behavior of complex shear wall structures. The analysis escalates with parametric variation in steel thickness sandwiching the stipulated amount of concrete panels. Modeling details of structural components, contact conditions between steel and concrete, associated boundary conditions and constitutive relationships for the cyclic loading are explained. Later, the load versus displacement curves, peak load and ultimate strength values, hysteretic characteristics and deflection profiles are verified with experimental data. The convergence of the numerical outcomes has been discussed to conclude the remarks.

  14. Hydrophilic behavior of graphene and graphene-based materials.

    Science.gov (United States)

    Accordino, Sebastián R; Montes de Oca, Joan Manuel; Rodriguez Fris, J Ariel; Appignanesi, Gustavo A

    2015-10-21

    Graphene and the graphene-based materials like graphite, carbon nanotubes, and fullerenes are not only usually regarded as hydrophobic but also have been widely employed as paradigms for the investigation of the behavior of water under nonpolar confinement, a question of major concern for fields ranging from biology to materials design. However, some experimental and theoretical insights seem to contradict, at least partially, such a picture. In this work, we will provide firm evidence for a neat hydrophilic nature of graphene surfaces. Our molecular dynamics studies will demonstrate that parallel graphene sheets present a strong tendency to remain fully hydrated for moderately long times (even when the equilibrium state is indeed the collapse of the plates), and thus, they are less prone to self-assembly than model hydrophobic surfaces we shall employ as control which readily undergo a hydrophobic collapse. Potential of mean force calculations will indeed make evident that the solvent exerts a repulsive contribution on the self-assembly of graphene surfaces. Moreover, we shall also quantify graphene hydrophilicity by means of the calculation of water density at two pressures and water density fluctuations. This latter study has never been performed on graphene and represents a means both to confirm and to quantify its neat hydrophilic behavior. We shall also make evident the relevance of the mildly attractive water-carbon interactions, since their artificial weakening will be shown to revert from typically hydrophilic to typically hydrophobic behavior.

  15. Identification of Nonlinear Dynamic Behavior and Failure for Riveted Joint Assemblies

    Directory of Open Access Journals (Sweden)

    B. Langrand

    2000-01-01

    Full Text Available Many different types of rivets need to be modeled to analyze the crashworthiness of aircraft structures. A numerical procedure based on FE modeling and characterization of material failure constitutive models is proposed herein with the aim of limiting the costs of experimental procedures otherwise necessary to obtain these data. Quasi-static and dynamic experiments were carried out on elementary tension (punched and shear (riveted specimens. No strain rate sensitivity was detected in the failure behavior of the riveted joint assemblies. Experimental data were used to identify the Gurson damage parameters of each material (2024-T351 and 7050 aluminum alloys for the sheet metal plate and the rivet respectively by an inverse method. Characterization gave rise to satisfactory correlation between FE models and experiments. Optimized parameters were validated for each material by means of a uniaxial tension test for the sheet metal plate and an ARCAN type specimen in pure tension for the rivet.

  16. Pyrene-Based Small Molecular Nonlinear Optical Materials Modified by ``Click-Reaction''

    Science.gov (United States)

    Liang, Pengxia; Li, Zhengqiang; Mi, Yongsheng; Yang, Zhou; Wang, Dong; Cao, Hui; He, Wanli; Yang, Huai

    2015-08-01

    Two pyrene derivatives were successfully synthesized via an efficient copper(I)-catalyzed azide alkyne 1,3-dipolar cycloaddition. The photophysical and electrochemical properties were characterized using ultraviolet-visible absorption spectra, fluorescence spectra, cyclic voltammograms and density functional theory modulations. These results showed that the symmetry structure of these derivatives formed an electron-delocalized organic system, which have larger effects in achieving a third-order nonlinear optical (NLO) response. The third-order nonlinear properties including the nonlinear absorption and the nonlinear susceptibilities investigated by Z-scan technique indicate that the title compounds can serve as a promising candidate for third-order NLO applications.

  17. γ-ray shielding behaviors of some nuclear engineering materials

    Energy Technology Data Exchange (ETDEWEB)

    Mann, Kulwinder Singh [Dept. of Physics, D.A.V. College, Punjab (India)

    2017-06-15

    The essential requirement of a material to be used for engineering purposes at nuclear establishments is its ability to attenuate the most penetrating ionizing radiations, gamma (γ)-rays. Mostly, high-Z materials such as heavy concrete, lead, mercury, and their mixtures or alloys have been used in the construction of nuclear establishments and thus termed as nuclear engineering materials (NEM). The NEM are classified into two categories, namely opaque and transparent, depending on their behavior towards the visible spectrum of EM waves. The majority of NEM are opaque. By contrast, various types of glass, which are transparent to visible light, are necessary at certain places in the nuclear establishments. In the present study, γ-ray shielding behaviors (GSB) of six glass samples (transparent NEM) were evaluated and compared with some opaque NEM in a wide range of energy (15 keV–15 MeV) and optical thickness (OT). The study was performed by computing various γ-ray shielding parameters (GSP) such as the mass attenuation coefficient, equivalent atomic number, and buildup factor. A self-designed and validated computer-program, the buildup factor-tool, was used for various computations. It has been established that some glass samples show good GSB, thus can safely be used in the construction of nuclear establishments in conjunction with the opaque NEM as well.

  18. On the Mechanical Behavior of Advanced Composite Material Structures

    Science.gov (United States)

    Vinson, Jack

    During the period between 1993 and 2004, the author, as well as some colleagues and graduate students, had the honor to be supported by the Office of Naval Research to conduct research in several aspects of the behavior of structures composed of composite materials. The topics involved in this research program were numerous, but all contributed to increasing the understanding of how various structures that are useful for marine applications behaved. More specifically, the research topics focused on the reaction of structures that were made of fiber reinforced polymer matrix composites when subjected to various loads and environmental conditions. This included the behavior of beam, plate/panel and shell structures. It involved studies that are applicable to fiberglass, graphite/carbon and Kevlar fibers imbedded in epoxy, polyester and other polymeric matrices. Unidirectional, cross-ply, angle ply, and woven composites were involved, both in laminated, monocoque as well as in sandwich constructions. Mid-plane symmetric as well as asymmetric laminates were studied, the latter involving bending-stretching coupling and other couplings that only can be achieved with advanced composite materials. The composite structures studied involved static loads, dynamic loading, shock loading as well as thermal and hygrothermal environments. One major consideration was determining the mechanical properties of composite materials subjected to high strain rates because the mechanical properties vary so significantly as the strain rate increases. A considerable number of references are cited for further reading and study for those interested.

  19. γ-Ray Shielding Behaviors of Some Nuclear Engineering Materials

    Directory of Open Access Journals (Sweden)

    Kulwinder Singh Mann

    2017-06-01

    Full Text Available The essential requirement of a material to be used for engineering purposes at nuclear establishments is its ability to attenuate the most penetrating ionizing radiations, gamma (γ-rays. Mostly, high-Z materials such as heavy concrete, lead, mercury, and their mixtures or alloys have been used in the construction of nuclear establishments and thus termed as nuclear engineering materials (NEM. The NEM are classified into two categories, namely opaque and transparent, depending on their behavior towards the visible spectrum of EM waves. The majority of NEM are opaque. By contrast, various types of glass, which are transparent to visible light, are necessary at certain places in the nuclear establishments. In the present study, γ-ray shielding behaviors (GSB of six glass samples (transparent NEM were evaluated and compared with some opaque NEM in a wide range of energy (15 keV–15 MeV and optical thickness (OT. The study was performed by computing various γ-ray shielding parameters (GSP such as the mass attenuation coefficient, equivalent atomic number, and buildup factor. A self-designed and validated computer-program, the buildup factor-tool, was used for various computations. It has been established that some glass samples show good GSB, thus can safely be used in the construction of nuclear establishments in conjunction with the opaque NEM as well.

  20. Nonlinear optics in germanium mid-infrared fiber material: Detuning oscillations in femtosecond mid-infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    M. Ordu

    2017-09-01

    Full Text Available Germanium optical fibers hold great promise in extending semiconductor photonics into the fundamentally important mid-infrared region of the electromagnetic spectrum. The demonstration of nonlinear response in fabricated Ge fiber samples is a key step in the development of mid-infrared fiber materials. Here we report the observation of detuning oscillations in a germanium fiber in the mid-infrared region using femtosecond dispersed pump-probe spectroscopy. Detuning oscillations are observed in the frequency-resolved response when mid-infrared pump and probe pulses are overlapped in a fiber segment. The oscillations arise from the nonlinear frequency resolved nonlinear (χ(3 response in the germanium semiconductor. Our work represents the first observation of coherent oscillations in the emerging field of germanium mid-infrared fiber optics.

  1. Growth of thin films of organic nonlinear optical materials by vapor growth processes - An overview and examination of shortfalls

    Science.gov (United States)

    Frazier, D. O.; Penn, B. G.; Witherow, W. K.; Paley, M. S.

    1991-01-01

    Research on the growth of second- and third-order nonlinear optical (NLO) organic thin film by vapor deposition is reviewed. Particular attention is given to the experimental methods for growing thin films of p-chlorophenylurea, diacetylenes, and phthalocyanines; characteristics of the resulting films; and approaches for advancing thin film technology. It is concluded that the growth of NLO thin films by vapor processes is a promising method for the fabrication of planar waveguides for nonlinear optical devices. Two innovative approaches are proposed including a method of controlling the input beam frequency to maximize nonlinear effects in thin films and single crystals, and the alternate approach to the molecular design of organic NLO materials by increasing the transition dipole moment between ground and excited states of the molecule.

  2. On the response of nonlinear viscoelastic materials in creep and stress relaxation experiments in the lubricated squeeze flow setting

    Science.gov (United States)

    Řehoř, Martin; Pr&oring; ša, Vít; T&oring; ma, Karel

    2016-10-01

    Rigorous analysis of the response of nonlinear materials to step inputs requires one to simultaneously handle the discontinuity, differentiation, and nonlinearity. This task is however beyond the reach of the standard theories such as the classical theory of distributions and presents a considerable mathematical difficulty. New advanced mathematical tools are necessary to handle the challenge. An elegant and relatively easy-to-use framework capable of accomplishing the task is provided by the Colombeau algebra, which is a generalisation of the classical theory of distributions to the nonlinear setting. We use the Colombeau algebra formalism and derive explicit formulae describing the response of incompressible Maxwell viscoelastic fluid subject to step load/deformation in the lubricated squeeze flow setting.

  3. Deformation and fatigue behavior of SSME turbopump blade materials

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1987-01-01

    Directionally solidified and single crystal superalloys which are intended for use as turbopump blade materials are anisotropic both elastically and plastically. Therefore, isotropic constitutive models must be modified. Several models which are now being developed are based on metallurgical theories of deformation in these types of alloys. However, these theories have not been fully justified, and the temperature and strain regimes over which they may be valid are poorly defined. The objective of this work is to study the deformation behavior of the alloys, in order to determine the validity of these models and to thereby support the ongoing research efforts in solid mechanics.

  4. Characteristics of tritium release behavior from solid breeder materials

    Energy Technology Data Exchange (ETDEWEB)

    Kinjyo, T.; Nishikawa, M.; Yamashita, N.; Koyama, T.; Suematsu, K.; Fukada, S. [Graduate School of Engineering Science, Kyushu Univ., Fukuoka 812-8581 (Japan); Enoeda, M. [Naka Establishment, Japan Atomic Energy Agency, Ibaraki 319-1195 (Japan)

    2008-07-15

    A tritium release model has been developed by the present authors. The tritium release curves estimated by this tritium model give good agreement with experimental curves for Li {sub 4}SiO{sub 4}, Li{sub 2}TiO{sub 3}, Li{sub 2}ZrO{sub 3} or LiAlO{sub 2} under various purge gas conditions in our out-of-pile bred tritium release. The characteristics of tritium release behavior from various solid breeder materials carried out by us and in EXOTIC experiments at Petten are discussed in this study. (authors)

  5. Energy based model for temperature dependent behavior of ferromagnetic materials

    Science.gov (United States)

    Sah, Sanjay; Atulasimha, Jayasimha

    2017-03-01

    An energy based model for temperature dependent anhysteretic magnetization curves of ferromagnetic materials is proposed and benchmarked against experimental data. This is based on the calculation of macroscopic magnetic properties by performing an energy weighted average over all possible orientations of the magnetization vector. Most prior approaches that employ this method are unable to independently account for the effect of both inhomogeneity and temperature in performing the averaging necessary to model experimental data. Here we propose a way to account for both effects simultaneously and benchmark the model against experimental data from 5 K to 300 K for two different materials in both annealed (fewer inhomogeneities) and deformed (more inhomogeneities) samples. This demonstrates that this framework is well suited to simulate temperature dependent experimental magnetic behavior.

  6. High-order nonlinear optical processes in ablated carbon-containing materials: Recent approaches in development of the nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range

    Science.gov (United States)

    Ganeev, R. A.

    2017-08-01

    The nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range became a versatile tool for the analysis of the optical, structural and morphological properties of matter. The carbon-contained materials have shown the advanced properties among other studied species, which allowed both the definition of the role of structural properties on the nonlinear optical response and the analysis of the fundamental features of carbon as the attractive material for generation of coherent short-wavelength radiation. We review the studies of the high-order harmonic generation by focusing ultrashort pulses into the plasmas produced during laser ablation of various organic compounds. We discuss the role of ionic transitions of ablated carbon-containing molecules on the harmonic yield. We also show the similarities and distinctions of the harmonic and plasma spectra of organic compounds and graphite. We discuss the studies of the generation of harmonics up to the 27th order (λ = 29.9 nm) of 806 nm radiation in the boron carbide plasma and analyze the advantages and disadvantages of this target compared with the ingredients comprising B4C (solid boron and graphite) by comparing plasma emission and harmonic spectra from three species. We also show that the coincidence of harmonic and plasma emission wavelengths in most cases does not cause the enhancement or decrease of the conversion efficiency of this harmonic.

  7. Uncertainty of the Numerical Solution of a Nonlinear System's Long-term Behavior and Global Convergence of the Numerical Pattern

    Institute of Scientific and Technical Information of China (English)

    胡淑娟; 丑纪范

    2004-01-01

    The computational uncertainty principle in nonlinear ordinary differential equations makes the numerical solution of the long-term behavior of nonlinear atmospheric equations have no meaning. The main reason is that, in the error analysis theory of present-day computational mathematics, the non-linear process between truncation error and rounding erroris treated as a linear operation. In this paper, based on the operator equations of large-scale atmospheric movement, the above limitation is overcome by using the notion of cell mapping. Through studying the global asymptotic characteristics of the numerical pattern of the large-scale atmospheric equations, the definitions of the global convergence and an appropriate discrete algorithm of the numerical pattern are put forward. Three determinant theorems about the global convergence of the numerical pattern are presented, which provide the theoretical basis for constructing the globally convergent numerical pattern. Further, it is pointed out that only a globally convergent numerical pattern can improve the veracity of climatic prediction.

  8. Synthesis, characterization and femtosecond nonlinear saturable absorption behavior of copper phthalocyanine nanocrystals doped-PMMA polymer thin films

    Science.gov (United States)

    Zongo, S.; Dhlamini, M. S.; Neethling, P. H.; Yao, A.; Maaza, M.; Sahraoui, B.

    2015-12-01

    In this work, we report the femtosecond nonlinear saturable absorption response of synthesized copper phthalocyanine nanocrystals (CPc-NCs)-doped PMMA polymer thin films. The samples were initially characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV-Vis and scanning electron microscopy (SEM) techniques. The crystalline phase and morphological analysis revealed nanocrystals of monoclinic structure with an average crystallite size between 31.38 nm and 42.5 nm. The femtosecond Z-scan study at 800 nm central wavelength indicated a saturable absorption behavior of which the mechanism is closely related to the surface plasmon resonance (SPR) of the particles. This nonlinear effect could potentially make the CPc-NCs useful in nonlinear optical devices.

  9. The Nonlinear Behavior of Vibrational Conveyers with Single-Mass Crank-and-Rod Exciters

    Directory of Open Access Journals (Sweden)

    G. Füsun Alışverişçi

    2012-01-01

    Full Text Available The single-mass, crank-and-rod exciters vibrational conveyers have a trough supported on elastic stands which are rigidly fastened to the trough and a supporting frame. The trough is oscillated by a common crank drive. This vibration causes the load to move forward and upward. The moving loads jump periodically and move forward with relatively small vibration. The movement is strictly related to vibrational parameters. This is applicable in laboratory conditions in the industry which accommodate a few grams of loads, up to those that accommodate tons of loading capacity. In this study I explore the transitional behavior across resonance, during the starting of a single degree of freedom vibratory system excited by crank-and-rod. A loaded vibratory conveyor is more safe to start than an empty one. Vibrational conveyers with cubic nonlinear spring and ideal vibration exciter have been analyzed analytically for primary and secondary resonance by the Method of Multiple Scales, and numerically. The approximate analytical results obtained in this study have been compared with the numerical results and have been found to be well matched.

  10. Nonlinear seismic behavior of a CANDU containment building subjected to near-field ground motions

    Energy Technology Data Exchange (ETDEWEB)

    Choi, In Kil; Ahn, Seong Moon; Choun, Young Sun; Seo, Jeong Moon [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2004-07-01

    The standard response spectrum proposed by US NRC has been used as a design earthquake for the design of Korean nuclear power plant structures. A survey on some of the Quaternary fault segments near Korean nuclear power plants is ongoing. It is likely that these faults will be identified as active ones. If the faults are confirmed as active ones, it will be necessary to reevaluate the seismic safety of the nuclear power plants located near the fault. Near-fault ground motions are the ground motions that occur near an earthquake fault. In general, the near-fault ground motion records exhibit a distinctive long period pulse like time history with very high peak velocities. These features are induced by the slip of the earthquake fault. Near-fault ground motions, which have caused much of the damage in recent major earthquakes, can be characterized by a pulse-like motion that exposes the structure to a high input energy at the beginning of the motion. In this study, nonlinear dynamic time-history analyses were performed to investigate the seismic behavior of a CANDU containment structure subjected to various earthquake ground motions including the near-field ground motions.

  11. Controlling the dynamical behavior of nonlinear fiber ring resonators with balanced loss and gain

    CERN Document Server

    Deka, Jyoti P; Sarma, Amarendra K

    2015-01-01

    We show the possibility of controlling the dynamical behavior of a single fiber ring (SFR) resonator system with the fiber being an amplified (gain) channel and the ring being attenuated (loss) nonlinear dielectric medium. The system considered here is a simple alteration in the basic building block of the parity time (PT) symmetric synthetic coupler structures reported in A. Regensburger et al., Nature 488, 167 (2012). We find that this result in a dynamically controllable algorithm for the chaotic dynamics inherent in the system. We have also shown the dependence of the period doubling point upon the input amplitude, emphasizing on the dynamical aspects of our system. Moreover, the fact that the resonator essentially plays the role of a damped harmonic oscillator has been elucidated with the non-zero intensity inside the resonator due to constant influx of input light. This study may be a step forward to further investigations in regard to the inter-connectivity between the PT symmetry and chaos along with ...

  12. Influence of surface roughness on nonlinear flow behaviors in 3D self-affine rough fractures: Lattice Boltzmann simulations

    Science.gov (United States)

    Wang, Min; Chen, Yi-Feng; Ma, Guo-Wei; Zhou, Jia-Qing; Zhou, Chuang-Bing

    2016-10-01

    This study investigates the impacts of surface roughness on the nonlinear fluid flow through three-dimensional (3D) self-affine rock fractures, whose original surface roughness is decomposed into primary roughness (i.e. the large-scale waviness of the fracture morphology) and secondary roughness (i.e. the small-scale unevenness) with a wavelet analysis technique. A 3D Lattice Boltzmann method (LBM) is adopted to predict the flow physics in rock fractures numerically created with and without consideration of the secondary roughness, respectively. The simulation results show that the primary roughness mostly controls the pressure distribution and fracture flow paths at a large scale, whereas the secondary roughness determines the nonlinear properties of the fluid flow at a local scale. As the pressure gradient increases, the secondary roughness enhances the local complexity of velocity distribution by generating and expanding the eddy flow and back flow regions in the vicinity of asperities. It was found that the Forchheimer's law characterizes well the nonlinear flow behavior in fractures of varying roughness. The inertial effects induced by the primary roughness differ only marginally in fractures with the roughness exponent varying from 0.5 to 0.8, and it is the secondary roughness that significantly enhances the nonlinear flow and leads to earlier onset of nonlinearity. Further examined were the effects of surface roughness on the transmissivity, hydraulic aperture and the tortuosity of flow paths, demonstrating again the dominant role of the secondary roughness, especially for the apparent transmissivity and the equivalent hydraulic aperture at high pressure gradient or high Reynolds number. The results may enhance our understanding of the role of surface roughness in the nonlinear flow behaviors in natural rock fractures.

  13. Adsorption of albumin on prosthetic materials: implication for tribological behavior.

    Science.gov (United States)

    Serro, A P; Gispert, M P; Martins, M C L; Brogueira, P; Colaço, R; Saramago, B

    2006-09-01

    The orthopedic prosthesis used to substitute damaged natural joints are lubricated by a pseudosynovial fluid that contains biological macromolecules with potential boundary lubrication properties. Proteins are some of those macromolecules whose role in the lubrication process is not yet completely understood. In a previous work, we investigated the influence of the presence of albumin, the major synovial protein, upon the tribological behavior of three of the most used pairs of artificial joint materials: ultra high molecular weight polyethylene (UHMWPE) against counterfaces of alumina, CoCrMo alloy, and 316L stainless steel. Albumin was found to cause a significant decrease in the friction coefficient when the counterfaces were metallic because transfer of UHMWPE was avoided, but this effect was much weaker in the case of alumina. The objective of the present work was to look for an explanation for these differences in tribological behavior in terms of albumin adsorption. With this goal, studies on adsorption of bovine serum albumin (BSA) on the counterface materials, from a biological model fluid (Hanks' balanced salt solution), were carried out using radiolabeled albumin ((125)I-BSA), X-ray photoelectron spectroscopy, and atomic force microscopy. The conclusion from all techniques is that the driving force for albumin adsorption is higher on the metals than on alumina. These results confirm that the greater the amount of protein adsorbed on the counterface, the more efficient is the protection against the transfer of polymeric film to the counterface.

  14. Long Time Behavior for a System of Differential Equations with Non-Lipschitzian Nonlinearities

    Directory of Open Access Journals (Sweden)

    Nasser-Eddine Tatar

    2014-01-01

    Full Text Available We consider a general system of nonlinear ordinary differential equations of first order. The nonlinearities involve distributed delays in addition to the states. In turn, the distributed delays involve nonlinear functions of the different variables and states. An explicit bound for solutions is obtained under some rather reasonable conditions. Several special cases of this system may be found in neural network theory. As a direct application of our result it is shown how to obtain global existence and, more importantly, convergence to zero at an exponential rate in a certain norm. All these nonlinearities (including the activation functions may be non-Lipschitz and unbounded.

  15. Modulation of nonlinear resistive switching behavior of a TaOx-based resistive device through interface engineering

    Science.gov (United States)

    Wang, Zongwei; Kang, Jian; Yu, Zhizhen; Fang, Yichen; Ling, Yaotian; Cai, Yimao; Huang, Ru; Wang, Yangyuan

    2017-02-01

    A resistive switching device with inherent nonlinear characteristics through a delicately engineered interfacial layer is an ideal component to be integrated into passive crossbar arrays for the suppression of sneaking current, especially in ultra-dense 3D integration. In this paper, we demonstrated a TaOx-based bipolar resistive switching device with a nearly symmetrical bi-directional nonlinear feature through interface engineering. This was accomplished by introducing an ultra-thin interfacial layer (SiO2-x) with unique features, including a large band gap and a certain level of negative heat of oxide formation between the top electrode (TiN) and resistive layer (TaOx). The devices exhibit excellent nonlinear property under both positive and negative bias. Modulation of the inherent nonlinearity as well as the resistive switching mechanism are comprehensively studied by scrutinizing the results of the experimental control groups and the extensive characterizations including detailed compositional analysis, which suggests that the underlying mechanism of the nonlinear behavior is associatively governed by the serially connected metallic conductive filament and Flower-Nordheim tunneling barrier formed by the SiO2-x interface layer. The proposed device in this work has great potential to be implemented in future massive storage memory applications of high-density selector-free crossbar structure.

  16. Mechanical behavior of materials engineering methods for deformation, fracture, and fatigue

    CERN Document Server

    Dowling, Norman E

    2012-01-01

    For upper-level undergraduate engineering courses in Mechanical Behavior of Materials. Mechanical Behavior of Materials, 4/e introduces the spectrum of mechanical behavior of materials, emphasizing practical engineering methods for testing structural materials to obtain their properties, and predicting their strength and life when used for machines, vehicles, and structures. With its logical treatment and ready-to-use format, it is ideal for upper-level undergraduate students who have completed elementary mechanics of materials courses.

  17. Model of anisotropic nonlinearity in self-defocusing photorefractive media.

    Science.gov (United States)

    Barsi, C; Fleischer, J W

    2015-09-21

    We develop a phenomenological model of anisotropy in self-defocusing photorefractive crystals. In addition to an independent term due to nonlinear susceptibility, we introduce a nonlinear, non-separable correction to the spectral diffraction operator. The model successfully describes the crossover between photovoltaic and photorefractive responses and the spatially dispersive shock wave behavior of a nonlinearly spreading Gaussian input beam. It should prove useful for characterizing internal charge dynamics in complex materials and for accurate image reconstruction through nonlinear media.

  18. Nonlinear and nonequilibrium dynamics in geomaterials.

    Science.gov (United States)

    TenCate, James A; Pasqualini, Donatella; Habib, Salman; Heitmann, Katrin; Higdon, David; Johnson, Paul A

    2004-08-01

    The transition from linear to nonlinear dynamical elasticity in rocks is of considerable interest in seismic wave propagation as well as in understanding the basic dynamical processes in consolidated granular materials. We have carried out a careful experimental investigation of this transition for Berea and Fontainebleau sandstones. Below a well-characterized strain, the materials behave linearly, transitioning beyond that point to a nonlinear behavior which can be accurately captured by a simple macroscopic dynamical model. At even higher strains, effects due to a driven nonequilibrium state, and relaxation from it, complicate the characterization of the nonlinear behavior.

  19. A new method of binary addition scheme with massive use of non-linear material based system

    Institute of Scientific and Technical Information of China (English)

    Kuladeep Roy Chowdhury; Sourangshu Mukhopadhyay

    2003-01-01

    The limitations in electronics in arithmetic, algebraic & logic processing are well known. Very high speedperformance (above GHz) are not expected at all in conventional electronic mechanism. To achieve highspeed performance we may think on the introduction of optics instead of electronics for information pro-cessing and computing. Non-linear optical material is a successful candidate in this regard to play a majorrole in the optically controlled switching systems and therefore in all-optical parallel computation thesematerials can show a very good potential aspect. In this paper, we have proposed a new method of anoptical half adder as well as full adder circuit for binary addition using non-linear and linear optical ma-terials.

  20. Crystal structure, optical and thermal studies of a new organic nonlinear optical material: L-Histidinium maleate 1.5-hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Gonsago, C. Alosious [Department of Physics, A. J. College of Engineering, Chennai 603103 (India); Albert, Helen Merina [Department of Physics, Sathyabama University, Chennai 600119 (India); Karthikeyan, J. [Department of Chemistry, Sathyabama University, Chennai 600119 (India); Sagayaraj, P. [Department of Physics, Loyola College, Chennai 600034 (India); Pragasam, A. Joseph Arul, E-mail: drjosephsu@gmail.com [Department of Physics, Sathyabama University, Chennai 600119 (India)

    2012-07-15

    Highlights: ► L-Histidinium maleate 1.5-hydrate, a new organic crystal has been grown for the first time. ► The crystal structure is reported for the first time (CCDC 845975). ► The crystal belongs to monoclinic system with space group P2{sub 1}, Z = 4, a = 11.4656(7) Å, b = 8.0530(5) Å, c = 14.9705(9) Å and β = 101.657(2)°. ► The optical absorption study substantiates the complete transparency of the crystal. ► Kurtz powder SHG test confirms the nonlinear property of the crystal. -- Abstract: A new organic nonlinear optical material L-histidinium maleate 1.5-hydrate (LHM) with the molecular formula C{sub 10}H{sub 16}N{sub 3}O{sub 7.5} has been successfully synthesized from aqueous solution by slow solvent evaporation method. The structural characterization of the grown crystal was carried out by single crystal X-ray diffraction at 293(2) K. In the crystal, molecules are linked through inter and intramolecular N-H⋯O and O-H⋯O hydrogen bonds, generate edge fused ring motif. The hydrogen bonded motifs are linked to each other to form a three dimensional network. The FT-IR spectroscopy was used to identify the functional groups of the synthesized compound. The optical behavior of the grown crystal was examined by UV–visible spectral analysis, which shows that the optical absorption is almost negligible in the wavelength range 280–1300 nm. The nonlinear optical property was confirmed by the powder technique of Kurtz and Perry. The thermal behavior of the grown crystal was analyzed by thermogravimetric analysis.

  1. Modeling the Mechanical Behavior of Ceramic Matrix Composite Materials

    Science.gov (United States)

    Jordan, William

    1998-01-01

    Ceramic matrix composites are ceramic materials, such as SiC, that have been reinforced by high strength fibers, such as carbon. Designers are interested in using ceramic matrix composites because they have the capability of withstanding significant loads while at relatively high temperatures (in excess of 1,000 C). Ceramic matrix composites retain the ceramic materials ability to withstand high temperatures, but also possess a much greater ductility and toughness. Their high strength and medium toughness is what makes them of so much interest to the aerospace community. This work concentrated on two different tasks. The first task was to do an extensive literature search into the mechanical behavior of ceramic matrix composite materials. This report contains the results of this task. The second task was to use this understanding to help interpret the ceramic matrix composite mechanical test results that had already been obtained by NASA. Since the specific details of these test results are subject to the International Traffic in Arms Regulations (ITAR), they are reported in a separate document (Jordan, 1997).

  2. Behavior of radioactive materials and safety stock of contaminated sludge.

    Science.gov (United States)

    Tsushima, Ikuo

    2017-01-28

    The radioactive fallout from the Fukushima Dai-ichi nuclear power plant disaster in 2011 has flowed into and accumulated in many wastewater treatment plants (WWTPs) via sewer systems; this has had a negative impact on WWTPs in eastern Japan. The behavior of radioactive materials was analyzed at four WWTPs in the Tohoku and Kanto regions to elucidate the mechanism by which radioactive materials are concentrated during the sludge treatment process from July 2011 to March 2013. Furthermore, numerical simulations were conducted to study the safe handling of contaminated sewage sludge stocked temporally in WWTPs. Finally, a dissolution test was conducted by using contaminated incinerated ash and melted slag derived from sewage sludge to better understand the disposal of contaminated sewage sludge in landfills. Measurements indicate that a large amount of radioactive material accumulates in aeration tanks and is becoming trapped in the concentrated sludge during the sludge condensation process. The numerical simulation indicates that a worker's exposure around contaminated sludge is less than 1 µSv/h when maintaining an isolation distance of more than 10 m, or when shielding with more than 20-cm-thick concrete. The radioactivity level of the eluate was undetectable in 9 out of 12 samples; in the remaining three samples, the dissolution rates were 0.5-2.7%.

  3. MATHEMATICAL MODELING OF MUTUALLY BENEFICIAL RELATIONS BEETWEEN RAW MATERIAL PRODUCERS AND PROCESSORS BASED ON NONLINEAR DEMAND FUNCTION

    Directory of Open Access Journals (Sweden)

    Loyko V. I.

    2015-06-01

    Full Text Available Agricultural producers interested in marketing of raw materials, whereas processing companies are interested in the establishment of raw material zones, providing capacity utilization; therefore, the establishment of sustainable linkages between producers and processors of raw materials is an objective necessity. In the article, with the help of mathematical methods we examine the conditions of mutually beneficial economic relations between agricultural producers and processing enterprises. Mathematical model for estimating the profits of the company is built of the following conditions: producers sell processing plants raw materials, determined by the coefficient of the interest in the partnership at an agreed purchase price, and the remaining raw materials are processed, so they can sell their products independently. Profit of the processing plant is determined by the mathematical model. To describe the nonlinear market-based sales of goods from its retail price we used a hyperbolic demand function

  4. On Asymptotic Behavior and Blow-Up of Solutions for a Nonlinear Viscoelastic Petrovsky Equation with Positive Initial Energy

    Directory of Open Access Journals (Sweden)

    Gang Li

    2013-01-01

    Full Text Available This paper deals with the initial boundary value problem for the nonlinear viscoelastic Petrovsky equation utt+Δ2u−∫0tgt−τΔ2ux,τdτ−Δut−Δutt+utm−1ut=up−1u. Under certain conditions on g and the assumption that mbehavior and blow-up results for solutions with positive initial energy.

  5. Localized Effects in the Nonlinear Behavior of Sandwich Panels with a Transversely Flexible Core

    DEFF Research Database (Denmark)

    Frostig, Y.; Thomsen, Ole Thybo

    2005-01-01

    nonlinear analysis approach incorporates the effects of the vertical flexibility of the core, and it is based on the approach of the High-order Sandwich Panel Theory (HSAPT). The results demonstrate that the effects of localized loads, when taken into the geometrically nonlinear domain, change the response...

  6. Growth and characterization of benzaldehyde 4-nitro phenyl hydrazone (BPH) single crystal: A proficient second order nonlinear optical material

    Science.gov (United States)

    Saravanan, M.; Abraham Rajasekar, S.

    2016-04-01

    The crystals (benzaldehyde 4-nitro phenyl hydrazone (BPH)) appropriate for NLO appliance were grown by the slow cooling method. The solubility and metastable zone width measurement of BPH specimen was studied. The material crystallizes in the monoclinic crystal system with noncentrosymmetric space group of Cc. The optical precision in the whole visible region was found to be excellent for non-linear optical claim. Excellence of the grown crystal is ascertained by the HRXRD and etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of BPH sample at different temperatures was investigated to determine the hardness stability of the grown specimen. The piezoelectric temperament and the relative Second Harmonic Generation (for diverse particle sizes) of the material were also studied. The dielectric studies were executed at varied temperatures and frequencies to investigate the electrical properties. Photoconductivity measurement enumerates consummate of inducing dipoles due to strong incident radiation and also divulge the nonlinear behaviour of the material. The third order nonlinear optical properties of BPH crystals were deliberate by Z-scan method.

  7. Corrosion behavior of construction materials for ionic liquid hydrogen compressor

    DEFF Research Database (Denmark)

    Arjomand Kermani, Nasrin; Petrushina, Irina; Nikiforov, Aleksey Valerievich

    2016-01-01

    The corrosion behavior of various commercially available stainless steels and nickel-based alloys as possible construction materials for components which are in direct contact with one of five different ionic liquids was evaluated. The ionic liquids, namely: 1-ethyl-3-methylimidazolium triflate, 1...... liquid hydrogen compressor. An electrochemical cell was specially designed, and steady-state cyclic voltammetry was used to measure the corrosion resistance of the alloys in the ionic liquids at 23 °C, under atmospheric pressure. The results showed a very high corrosion resistance and high stability...... for all the alloys tested. The two stainless steels, AISI 316L and AISI 347 showed higher corrosion resistance compared to AISI 321 in all the ionic liquids tested. It was observed that small addition of molybdenum, tantalum, and niobium to the alloys increased the corrosion stability in the ionic liquids...

  8. Simulation of nonlinear benchmarks and sheet metal forming processes using linear and quadratic solid–shell elements combined with advanced anisotropic behavior models

    Directory of Open Access Journals (Sweden)

    WangPeng

    2016-01-01

    Full Text Available A family of prismatic and hexahedral solid‒shell (SHB elements with their linear and quadratic versions is presented in this paper to model thin 3D structures. Based on reduced integration and special treatments to eliminate locking effects and to control spurious zero-energy modes, the SHB solid‒shell elements are capable of modeling most thin 3D structural problems with only a single element layer, while describing accurately the various through-thickness phenomena. In this paper, the SHB elements are combined with fully 3D behavior models, including orthotropic elastic behavior for composite materials and anisotropic plastic behavior for metallic materials, which allows describing the strain/stress state in the thickness direction, in contrast to traditional shell elements. All SHB elements are implemented into ABAQUS using both standard/quasi-static and explicit/dynamic solvers. Several benchmark tests have been conducted, in order to first assess the performance of the SHB elements in quasi-static and dynamic analyses. Then, deep drawing of a hemispherical cup is performed to demonstrate the capabilities of the SHB elements in handling various types of nonlinearities (large displacements and rotations, anisotropic plasticity, and contact. Compared to classical ABAQUS solid and shell elements, the results given by the SHB elements show good agreement with the reference solutions.

  9. Viscoelasticity behavior for finite deformations, using a consistent hypoelastic model based on Rivlin materials

    Science.gov (United States)

    Altmeyer, Guillaume; Panicaud, Benoit; Rouhaud, Emmanuelle; Wang, Mingchuan; Roos, Arjen; Kerner, Richard

    2016-11-01

    When constructing viscoelastic models, rate-form relations appear naturally to relate strain and stress tensors. One has to ensure that these tensors and their rates are indifferent with respect to the change of observers and to the superposition with rigid body motions. Objective transports are commonly accepted to ensure this invariance. However, the large number of transport operators developed makes the choice often difficult for the user and may lead to physically inconsistent formulation of hypoelasticity. In this paper, a methodology based on the use of the Lie derivative is proposed to model consistent hypoelasticity as an equivalent incremental formulation of hyperelasticity. Both models are shown to be reversible and completely equivalent. Extension to viscoelasticity is then proposed from this consistent model by associating consistent hypoelastic models with viscous behavior. As an illustration, Mooney-Rivlin nonlinear elasticity is coupled with Newton viscosity and a Maxwell-like material is investigated. Numerical solutions are then presented to illustrate a viscoelastic material subjected to finite deformations for a large range of strain rates.

  10. Effects of natural enrichment materials on stress, memory and exploratory behavior in mice.

    Science.gov (United States)

    Acklin, Casey J; Gault, Ruth A

    2015-07-01

    Environmental enrichment is an essential component of laboratory animal housing that allows animals to engage in natural behaviors in an otherwise artificial setting. Previous research by the authors suggested that, compared with synthetic enrichment materials, natural materials were associated with lower stress levels in mice. Here, the authors compare the effects of different enrichment materials on stress, memory and exploratory behavior in Swiss Webster mice. Mice that were provided with natural enrichment materials had lower stress levels, better memory and greater exploratory behavior than did mice provided with synthetic enrichment materials or with no enrichment materials. These findings suggest that provision of natural enrichment materials can improve well-being of laboratory mice.

  11. Synthesis, crystal structure, growth, optical and third order nonlinear optical studies of 8HQ2C5N single crystal - An efficient third-order nonlinear optical material

    Energy Technology Data Exchange (ETDEWEB)

    Divya Bharathi, M.; Ahila, G.; Mohana, J. [Department of Physics, Presidency College, Chennai 600005 (India); Chakkaravarthi, G. [Department of Physics, CPCL Polytechnic College, Chennai 600068 (India); Anbalagan, G., E-mail: anbu24663@yahoo.co.in [Department of Nuclear Physics, University of Madras, Chennai 600025 (India)

    2017-05-01

    A neoteric organic third order nonlinear optical material 8-hydroxyquinolinium 2-chloro-5-nitrobenzoate dihydrate (8HQ2C5N) was grown by slow cooling technique using ethanol: water (1:1) mixed solvent. The calculated low value of average etch pit solidity (4.12 × 10{sup 3} cm{sup −2}) indicated that the title crystal contain less defects. From the single crystal X-ray diffraction data, it was endowed that 8HQ2C5N crystal belongs to the monoclinic system with centrosymmetric space group P2{sub 1}/c and the cell parameters values, a = 9.6546 (4) Ǻ, b = 7.1637(3) Ǻ, c = 24.3606 (12) Ǻ, α = γ = 90°, β = 92.458(2)° and volume = 1683.29(13) Ǻ{sup 3}. The FT-IR and FT-Raman spectrum were used to affirm the functional group of the title compound. The chemical structure of 8HQ2C5N was scrutinized by {sup 13}C and {sup 1}H NMR spectral analysis and thermal stability through the differential scanning calorimetry study. Using optical studies the lower cut-off wavelength and optical band gap of 8HQ2C5N were found to be 364 nm and 3.17 eV respectively. Using the single oscillator model suggested by Wemple – Didomenico, the oscillator energy (E{sub o}), the dispersion energy (E{sub d}) and static dielectric constant (ε{sub o}) were estimated. The third-order susceptibility were determined as Im χ{sup (3)} = 2.51 × 10{sup −5} esu and Re χ{sup (3)} = 4.46 × 10{sup −7} esu. The theoretical third-order nonlinear optical susceptibility χ{sup (3)} was calculated and the results were compared with experimental value. Photoluminescence spectrum of 8HQ2C5N crystal showed the yellow emission. The crystal had the single shot laser damage threshold of 5.562 GW/cm{sup 2}. Microhardness measurement showed that 8HQ2C5N belongs to a soft material category. - Highlights: • A new organic single crystals were grown and the crystal structure was reported. • Crystal possess, good transmittance, thermal and mechanical stability. • Single shot LDT value is found to be

  12. Numerical scheme for non-linear model of supercritical fluid extraction from polydisperse ground plant material: single transport system

    Science.gov (United States)

    Salamatin, A.

    2016-11-01

    Numerical algorithm is developed for modelling non-linear mass transfer process in supercritical fluid extraction (SFE). The ground raw material is considered as polydisperse, characterized by discrete number of effective particle fractions. Two continuous interacting counterparts separated by permeable membrane are distinguished in plant material build-up. The apoplast plays role of transport channels during extraction, and symplast contains extractable oil. The complete SFE model is non-linear as a result of non-linearity of oil dissolution kinetics. The computational scheme is based on the finite-volume approximation method and Thomas elimination procedure. The resulting system of algebraic equations is solved iteratively. Special attention is paid to polydisperse substrates, when particle scale characteristics of all fractions interact with each other through pore phase concentration on the vessel scale. Stability of the developed algorithm is demonstrated in numerical tests. Special iterative procedure guarantees a monotonic decrease of oil content in individual particles of substrate. It is also shown that in the limit of the so-called shrinking core approach the number of mesh nodes on a particle scale should be increased.

  13. Comparison of Two Xenograft Materials Used in Sinus Lift Procedures: Material Characterization and In Vivo Behavior

    Directory of Open Access Journals (Sweden)

    María Piedad Ramírez Fernández

    2017-06-01

    Full Text Available Detailed information about graft material characteristic is crucial to evaluate their clinical outcomes. The present study evaluates the physico-chemical characteristics of two xenografts manufactured on an industrial scale deproteinized at different temperatures (non-sintered and sintered in accordance with a protocol previously used in sinus lift procedures. It compares how the physico-chemical properties influence the material’s performance in vivo by a histomorphometric study in retrieved bone biopsies following maxillary sinus augmentation in 10 clinical cases. An X-ray diffraction analysis revealed the typical structure of hydroxyapatite (HA for both materials. Both xenografts were porous and exhibited intraparticle pores. Strong differences were observed in terms of porosity, crystallinity, and calcium/phosphate. Histomorphometric measurements on the bone biopsies showed statistically significant differences. The physic-chemical assessment of both xenografts, made in accordance with the protocol developed on an industrial scale, confirmed that these products present excellent biocompatibilitity, with similar characteristics to natural bone. The sintered HA xenografts exhibited greater osteoconductivity, but were not completely resorbable (30.80 ± 0.88% residual material. The non-sintered HA xenografts induced about 25.92 ± 1.61% of new bone and a high level of degradation after six months of implantation. Differences in the physico-chemical characteristics found between the two HA xenografts determined a different behavior for this material.

  14. Evidence for bifurcation and universal chaotic behavior in nonlinear semiconducting devices

    Energy Technology Data Exchange (ETDEWEB)

    Testa, J.; Perez, J.; Jeffries, C.

    1982-01-01

    Bifurcations, chaos, and extensive periodic windows in the chaotic regime are observed for a driven LRC circuit, the capacitive element being a nonlinear varactor diode. Measurements include power spectral analysis; real time amplitude data; phase portraits; and a bifurcation diagram, obtained by sampling methods. The effects of added external noise are studied. These data yield experimental determinations of several of the universal numbers predicted to characterize nonlinear systems having this route to chaos.

  15. Global Behavior Of Finite Energy Solutions To The $d$-Dimensional Focusing Nonlinear Schr\\"odinger Equation

    CERN Document Server

    Guevara, Cristi

    2012-01-01

    We study the global behavior of finite energy solutions to the $d$-dimensional focusing nonlinear Schr\\"odinger equation (NLS), $i \\partial_t u+\\Delta u+ |u|^{p-1}u=0, $ with initial data $u_0\\in H^1,\\; x \\in R^n$. The nonlinearity power $p$ and the dimension $d$ are such that the scaling index $s=\\frac{d}2-\\frac2{p-1}$ is between 0 and 1, thus, the NLS is mass-supercritical $(s>0)$ and energy-subcritical $(s1,$ then the solution exhibits a blowup behavior, that is, either a finite time blowup occurs, or there is a divergence of $H^1$ norm in infinite time. This work generalizes the results for the 3d cubic NLS obtained in a series of papers by Holmer-Roudenko and Duyckaerts-Holmer-Roudenko with the key ingredients, the concentration compactness and localized variance, developed in the context of the energy-critical NLS and Nonlinear Wave equations by Kenig and Merle.

  16. Investigation of hyperelastic models for nonlinear elastic behavior of demineralized and deproteinized bovine cortical femur bone.

    Science.gov (United States)

    Hosseinzadeh, M; Ghoreishi, M; Narooei, K

    2016-06-01

    In this study, the hyperelastic models of demineralized and deproteinized bovine cortical femur bone were investigated and appropriate models were developed. Using uniaxial compression test data, the strain energy versus stretch was calculated and the appropriate hyperelastic strain energy functions were fitted on data in order to calculate the material parameters. To obtain the mechanical behavior in other loading conditions, the hyperelastic strain energy equations were investigated for pure shear and equi-biaxial tension loadings. The results showed the Mooney-Rivlin and Ogden models cannot predict the mechanical response of demineralized and deproteinized bovine cortical femur bone accurately, while the general exponential-exponential and general exponential-power law models have a good agreement with the experimental results. To investigate the sensitivity of the hyperelastic models, a variation of 10% in material parameters was performed and the results indicated an acceptable stability for the general exponential-exponential and general exponential-power law models. Finally, the uniaxial tension and compression of cortical femur bone were studied using the finite element method in VUMAT user subroutine of ABAQUS software and the computed stress-stretch curves were shown a good agreement with the experimental data.

  17. Chiral pyrrolo[1,2-a]quinolines as second-order nonlinear optical materials

    NARCIS (Netherlands)

    Kelderman, E.; Kelderman, E.; Verboom, Willem; Engbersen, Johannes F.J.; Harkema, Sybolt; Heesink, G.J.T.; Heesink, G.J.T.; Lehmusvaara, E.; van Hulst, N.F.; Reinhoudt, David; Derhaeg, L.; Persoons, A.

    1992-01-01

    The synthesis and nonlinear optical properties of a series of chiral pyrrolo[1,2-a]quinolines la-e is presented. The microscopic hyperpolarizabilities (beta(z)) were determined by EFISH measurements and the macroscopic susceptibilities (X2) were estimated by the Kurtz powder test. A small fixed

  18. Simple setup for rapid testing of third-order nonlinear optical materials.

    Science.gov (United States)

    Horan, P; Blau, W; Byrne, H; Berglund, P

    1990-01-01

    A relatively inexpensive and versatile degenerate four-wave mixing setup is described utilizing a nitrogen laser pumped dye laser. Samples can be screened rapidly, which is demonstrated with the example of a semiconductor doped glass having a nonlinear susceptibility x((3)) ~ 10(-11)-10(-10) esu.

  19. Expanded porphyrins as third order non-linear optical materials: Some structure-function correlations

    Indian Academy of Sciences (India)

    Sabapathi Gokulnath; Tavarekere K Chandrashekar

    2008-01-01

    In this paper, the non-linear optical properties of representative core-modified expanded porphyrins have been investigated with an emphasis on the structure-property relationship between the aromaticity and conformational behaviour. It has been shown that the measured two-photon absorption cross section (2) values depend on the structure of macrocycle, its aromaticity and the number of -electrons in conjugation.

  20. Nonlinear dynamic analysis and state space representation of a manipulator under viscoelastic material conditions

    Directory of Open Access Journals (Sweden)

    Esfandiar, H.

    2013-05-01

    Full Text Available In this paper, based on the VoigtKelvin constitutive model, nonlinear dynamic modelling and state space representation of a viscoelastic beam acting as a flexible robotic manipulator is investigated. Complete nonlinear dynamic modelling of a viscoelastic beam without premature linearisation of dynamic equations is developed. The adopted method is capable of reproducing nonlinear dynamic effects, such as beam stiffening due to centrifugal and Coriolis forces induced by rotation of the joints. Structural damping effects on the models dynamic behaviour are also shown. A reliable model for a viscoelastic beam is subsequently presented. The governing equations of motion are derived using Hamiltons principle, and using the finite difference method, nonlinear partial differential equations are reduced to ordinary differential equations. For the purpose of flexible manipulator control, the standard form of state space equations for the viscoelastic link and the actuator is obtained. Simulation results indicate substantial improvements in dynamic behaviour, and a parameter sensitivity study is carried out to investigate the effect of structural damping on the vibration amplitude.

  1. Asymmetric induced cubic nonlinearities in homogeneous and quasi-phase-matched quadratic materials: signature and importance

    DEFF Research Database (Denmark)

    Bang, Ole; Corney, Joel Frederick

    2001-01-01

    In continuous-wave operation asymmetric induced nonlinearities induce an intensity-dependent phase mismatch that implies a nonzero so-called separatrix intensity, the crossing of which changes the one-period phase shift of the fundamental by Pi , with obvious use in switching applications.We deri...

  2. Nonlinear oscillations

    CERN Document Server

    Nayfeh, Ali Hasan

    1995-01-01

    Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim

  3. Global existence, asymptotic behavior and blowup of solutions for a class of nonlinear wave equations with dissipative term

    Science.gov (United States)

    Zhijian, Yang

    The paper studies the global existence, asymptotic behavior and blowup of solutions to the initial boundary value problem for a class of nonlinear wave equations with dissipative term. It proves that under rather mild conditions on nonlinear terms and initial data the above-mentioned problem admits a global weak solution and the solution decays exponentially to zero as t→+∞, respectively, in the states of large initial data and small initial energy. In particular, in the case of space dimension N=1, the weak solution is regularized to be a unique generalized solution. And if the conditions guaranteeing the global existence of weak solutions are not valid, then under the opposite conditions, the solutions of above-mentioned problem blow up in finite time. And an example is given.

  4. NON-LINEAR DYNAMIC BEHAVIOR OF THERMOELASTIC CIRCULAR PLATE WITH VARYING THICKNESS SUBJECTED TO NON- CONSERVATIVE LOADING

    Institute of Scientific and Technical Information of China (English)

    WANG Zhongmin; GAO Jingbo; LI Huixia; LIU Hongzhao

    2008-01-01

    The non-linear dynamic behaviors of thermoelastic circular plate with varying thickness subjected to radially uniformly distributed follower forces are considered. Two coupled non-linear differential equations of motion for this problem are derived in terms of the transverse deflection and radial displacement component of the mid-plane of the plate. Using the Kantorovich averaging method, the differential equation of mode shape of the plate is derived, and the eigenvalue problem is solved by using shooting method. The eigencurves for frequencies and critical loads of the circular plate with unmovable simply supported edge and clamped edge are obtained. The effects of the variation of thickness and temperature on the frequencies and critical loads of the thermoelastic circular plate subjected to radially uniformly distributed follower forces are then discussed.

  5. NONLINEAR BUCKLING BEHAVIOR OF DAMAGED COMPOSITE SANDWICH PLATES CONSIDERING THE EFFECT OF TEMPERATURE-DEPENDENT THERMAL AND MECHANICAL PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    Bai Ruixiang; Chen Haoran

    2001-01-01

    On the basis of the first-order shear deformation plate theory and the zig-zag deformation assumption, an incremental finite element formulation for nonlinear buckling analysis of the composite sandwich plate is deduced and the temperature-dependent thermal and mechanical properties of composite is considered. A finite element method for thermal or thermo-mechanical coupling nonlinear buckling analysis of the composite sandwich plate with an interfacial crack damage between face and core is also developed. Numerical results and discussions concerning some typical examples show that the effects of the variation of the thermal and mechanical properties with temperature, extermal compressive loading, size of the damage zone and piy angle of the faces on the thermal buckling behavior are significant.

  6. Updated Lagrangian finite element formulations of various biological soft tissue non-linear material models: a comprehensive procedure and review.

    Science.gov (United States)

    Townsend, Molly T; Sarigul-Klijn, Nesrin

    2016-01-01

    Simplified material models are commonly used in computational simulation of biological soft tissue as an approximation of the complicated material response and to minimize computational resources. However, the simulation of complex loadings, such as long-duration tissue swelling, necessitates complex models that are not easy to formulate. This paper strives to offer the updated Lagrangian formulation comprehensive procedure of various non-linear material models for the application of finite element analysis of biological soft tissues including a definition of the Cauchy stress and the spatial tangential stiffness. The relationships between water content, osmotic pressure, ionic concentration and the pore pressure stress of the tissue are discussed with the merits of these models and their applications.

  7. Failure and Ejection Behavior of Concrete Materials under Internal Blast

    Directory of Open Access Journals (Sweden)

    Haifu Wang

    2016-01-01

    Full Text Available In order to investigate the failure and ejection behavior of concrete materials under internal blast, the default Riedel-Hiermaier-Thoma (RHT concrete model in AUTODYN and a meshfree processor called SPH are employed in this numerical simulation. It is shown that the failure mechanisms are significantly different in these damaged zones. Crushed zone is caused by shear failure while fractured zone is induced by tensile failure, and spalled zone is formed by a combination of shear and tensile failure. In addition, the ejection velocity distribution of the fragmented concrete mass on free surface is examined. The results indicate that the ejection velocity declines monotonously with the increase of the distance to symmetry axis of computational model. On the wall of the prefabricated borehole, two types of fragmented concrete mass are analyzed, and bottom initiation is recommended to eject the fragmented concrete mass effectively. Moreover, an algorithm of average ejection speed is developed to effectively estimate the drill capacity of high velocity, energetic (HE projectiles. At last, the validity of numerical simulation is verified by physical experiments.

  8. An analytical and explicit multi-field coupled nonlinear constitutive model for Terfenol-D giant magnetostrictive material

    Science.gov (United States)

    Zhou, Hao-Miao; Li, Meng-Han; Li, Xiao-Hong; Zhang, Da-Guang

    2016-08-01

    For a giant magnetostrictive rod under the action of multiple physical loads, such as an external magnetic field, temperature and axial pre-stress, this paper proposes a general one-dimensional nonlinear magneto-thermo-mechanical coupled constitutive model. This model is based on the Taylor expansion of the elastic Gibbs free energy of giant magnetostrictive material and thermodynamic relations from the perspective of macro continuum mechanics. Predictions made using this model are in good agreement with experimental data for magnetization and the magnetostrictive strain curve under the collective effect of pre-stress and temperature. Additionally, the model overcomes the drawback of the existing magneto-thermo-mechanical constitutive model that cannot accurately predict the magnetization and magnetostrictive strain curve for different temperatures and pre-stresses. Furthermore, the constitutive model does not contain an implicit function and is compact, and can thus be applied in both situations of tensile and compressive stress and to both positive and negative magnetostrictive materials, and it is thus appropriate for engineering applications. Comprehensive analysis shows that the model fully describes the nonlinear coupling properties of a magnetic field, magnetostrictive strain and elasticity of a magnetostrictive material subjected to stress, a magnetic field and heat.

  9. Correlation Between Domain Behavior and Magnetic Properties of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Leib, Jeffrey Scott [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    Correlation between length scales in the field of magnetism has long been a topic of intensive study. The long-term desire is simple: to determine one theory that completely describes the magnetic behavior of matter from an individual atomic particle all the way up to large masses of material. One key piece to this puzzle is connecting the behavior of a material's domains on the nanometer scale with the magnetic properties of an entire large sample or device on the centimeter scale. In the first case study involving the FeSiAl thin films, contrast and spacing of domain patterns are clearly related to microstructure and stress. Case study 2 most clearly demonstrates localized, incoherent domain wall motion switching with field applied along an easy axis for a square hysteresis loop. In case study 3, axis-specific images of the complex Gd-Si-Ge material clearly show the influence of uniaxial anisotropy. Case study 4, the only study with the sole intent of creating domain structures for imaging, also demonstrated in fairly simple terms the effects of increasing stress on domain patterns. In case study 5, it was proven that the width of magnetoresistance loops could be quantitatively predicted using only MFM. When all of the case studies are considered together, a dominating factor seems to be that of anisotropy, both magneticrostaylline and stress induced. Any quantitative bulk measurements heavily reliant on K coefficients, such as the saturation fields for the FeSiAl films, Hc in cases 1, 3, and 5, and the uniaxial character of the Gd5(Si2Ge2), transferred to and from the domain scale quite well. In-situ measurements of domain rotation and switching, could also be strongly correlated with bulk magnetic properties, including coercivity, Ms, and hysteresis loop shape. In most cases, the qualitative nature of the domain structures, when properly considered, matched quite well to what might have been expected

  10. Correlation Between Domain Behavior and Magnetic Properties of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Scott Leib

    2003-05-31

    Correlation between length scales in the field of magnetism has long been a topic of intensive study. The long-term desire is simple: to determine one theory that completely describes the magnetic behavior of matter from an individual atomic particle all the way up to large masses of material. One key piece to this puzzle is connecting the behavior of a material's domains on the nanometer scale with the magnetic properties of an entire large sample or device on the centimeter scale. In the first case study involving the FeSiAl thin films, contrast and spacing of domain patterns are clearly related to microstructure and stress. Case study 2 most clearly demonstrates localized, incoherent domain wall motion switching with field applied along an easy axis for a square hysteresis loop. In case study 3, axis-specific images of the complex Gd-Si-Ge material clearly show the influence of uniaxial anisotropy. Case study 4, the only study with the sole intent of creating domain structures for imaging, also demonstrated in fairly simple terms the effects of increasing stress on domain patterns. In case study 5, it was proven that the width of magnetoresistance loops could be quantitatively predicted using only MFM. When all of the case studies are considered together, a dominating factor seems to be that of anisotropy, both magneticrostaylline and stress induced. Any quantitative bulk measurements heavily reliant on K coefficients, such as the saturation fields for the FeSiAl films, H{sub c} in cases 1, 3, and 5, and the uniaxial character of the Gd{sub 5}(Si{sub 2}Ge{sub 2}), transferred to and from the domain scale quite well. In-situ measurements of domain rotation and switching, could also be strongly correlated with bulk magnetic properties, including coercivity, M{sub s}, and hysteresis loop shape. In most cases, the qualitative nature of the domain structures, when properly considered, matched quite well to what might have been expected from theory and

  11. Measurement of Temperature Change in Nonlinear Optical Materials by Using the Z-Scan Technique

    Institute of Scientific and Technical Information of China (English)

    DONG Shu-Guang; YANG Jun-Yi; SHUI Min; YI Chuan-Xiang; LI Zhong-Guo; SONG Ying-Lin

    2011-01-01

    @@ Spatial and temporal changes of temperature in a novel polymer are investigated by using the Z-scan technique under ns laser pulse excitation.According to the open aperture Z-scan experimental results, the nonlinear absorption coefficient of the polymer is determined.By solving the diffusion equation of heat conduction induced by optical absorption, the spatial and temporal changes in temperature are obtained.This change in temperature drives the photo-acoustic and electromagnetic wave propagating in the polymer and induces the change in refractive index, which serves as a negative lens, and the closed aperture Z-scan shows a peak and valley profile.Based on the numerical calculation, we achieve a good fit to the closed-aperture Z-scan curve with an optimized nonlinear refractive index.This consistency attests the existence of temperature change in the solution, and the Z-scan technique is suitable to investigate this change in temperature.

  12. Laminate Analyses, Micromechanical Creep Response, and Fatigue Behavior of Polymer Matrix Composite Materials.

    Science.gov (United States)

    1982-12-01

    FATIGUE BEHAVIOR of POLYMER MATRIX COMPOSITE MATERIALS , 4 " .’* .. . . ". ... .. ... . . ~December 1982 41 .. FINAL REPORT .Army Research Office I I...DEPARTMENT REPORT UWME-DR-201-108-1 LAMINATE ANALYSES, MICROMECHANICAL CREEP RESPONSE, AND FATIGUE BEHAVIOR OF POLYMER MATRIX COMPOSITE MATERIALS...Behavior of Polymer Matrix Composite 16 Sept. 1979 - 30 Nov. 1982 Materials 6 PERFORMING ORG. REPORT NUMBER UWME-DR-201-108-1 7. AUTHOR(.) S. CONTRACT

  13. Backward phase-matching for nonlinear optical generation in negative-index materials

    Science.gov (United States)

    Lan, Shoufeng; Kang, Lei; Schoen, David T.; Rodrigues, Sean P.; Cui, Yonghao; Brongersma, Mark L.; Cai, Wenshan

    2015-08-01

    Metamaterials have enabled the realization of unconventional electromagnetic properties not found in nature, which provokes us to rethink the established rules of optics in both the linear and nonlinear regimes. One of the most intriguing phenomena in nonlinear metamaterials is `backward phase-matching', which describes counter-propagating fundamental and harmonic waves in a negative-index medium. Predicted nearly a decade ago, this process is still awaiting a definitive experimental confirmation at optical frequencies. Here, we report optical measurements showing backward phase-matching by exploiting two distinct modes in a nonlinear plasmonic waveguide, where the real parts of the mode refractive indices are 3.4 and -3.4 for the fundamental and the harmonic waves respectively. The observed peak conversion efficiency at the excitation wavelength of ~780 nm indicates the fulfilment of the phase-matching condition of k2ω = 2kω and n2ω = -nω, where the coherent harmonic wave emerges along a direction opposite to that of the incoming fundamental light.

  14. Family material hardship and chinese adolescents' problem behaviors: a moderated mediation analysis

    National Research Council Canada - National Science Library

    Sun, Wenqiang; Li, Dongping; Zhang, Wei; Bao, Zhenzhou; Wang, Yanhui

    2015-01-01

    ...; we used the family stress model framework to investigate parental depression and negative parenting as potential mediators of the relation between family material hardship and adolescents' problem behaviors...

  15. Dynamic Critical Behavior of Multi-Grid Monte Carlo for Two-Dimensional Nonlinear $\\sigma$-Models

    OpenAIRE

    Mana, Gustavo; Mendes, Tereza; Pelissetto, Andrea; Sokal, Alan D.

    1995-01-01

    We introduce a new and very convenient approach to multi-grid Monte Carlo (MGMC) algorithms for general nonlinear $\\sigma$-models: it is based on embedding an $XY$ model into the given $\\sigma$-model, and then updating the induced $XY$ model using a standard $XY$-model MGMC code. We study the dynamic critical behavior of this algorithm for the two-dimensional $O(N)$ $\\sigma$-models with $N = 3,4,8$ and for the $SU(3)$ principal chiral model. We find that the dynamic critical exponent $z$ vari...

  16. Probabilistic Multi-Factor Interaction Model for Complex Material Behavior

    Science.gov (United States)

    Abumeri, Galib H.; Chamis, Christos C.

    2010-01-01

    Complex material behavior is represented by a single equation of product form to account for interaction among the various factors. The factors are selected by the physics of the problem and the environment that the model is to represent. For example, different factors will be required for each to represent temperature, moisture, erosion, corrosion, etc. It is important that the equation represent the physics of the behavior in its entirety accurately. The Multi-Factor Interaction Model (MFIM) is used to evaluate the divot weight (foam weight ejected) from the external launch tanks. The multi-factor has sufficient degrees of freedom to evaluate a large number of factors that may contribute to the divot ejection. It also accommodates all interactions by its product form. Each factor has an exponent that satisfies only two points - the initial and final points. The exponent describes a monotonic path from the initial condition to the final. The exponent values are selected so that the described path makes sense in the absence of experimental data. In the present investigation, the data used were obtained by testing simulated specimens in launching conditions. Results show that the MFIM is an effective method of describing the divot weight ejected under the conditions investigated. The problem lies in how to represent the divot weight with a single equation. A unique solution to this problem is a multi-factor equation of product form. Each factor is of the following form (1 xi/xf)ei, where xi is the initial value, usually at ambient conditions, xf the final value, and ei the exponent that makes the curve represented unimodal that meets the initial and final values. The exponents are either evaluated by test data or by technical judgment. A minor disadvantage may be the selection of exponents in the absence of any empirical data. This form has been used successfully in describing the foam ejected in simulated space environmental conditions. Seven factors were required

  17. Energy Impacts of Nonlinear Behavior of PCM When Applied into Building Envelope

    Energy Technology Data Exchange (ETDEWEB)

    Tabares-Velasco, P. C. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2012-08-01

    Presented at the ASME 2012 6th International Conference on Energy Sustainability & 10th Fuel Cell Science, Engineering and Technology Conference on July 23-26, 2012, this study analyzes the effects a nonlinear enthalpy profile has on thermal performance and expected energy benefits for PCM-enhanced insulation.

  18. Effects on the Floor Response Spectra by the Nonlinear Behavior of a Seismic Base Isolation System

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyungkui; Kim, Jung Han; Choi, Inkil [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    An evaluation of safety being carried out for various risk factors of prevents for nuclear power plant accident. In general, an evaluation of the structural integrity was performed about seismic risk. In recent years, an assessment of integrity of internal equipment being carried out for earthquake loads owing to the possibility of severe accidents caused by the destruction of internal equipment or a blackout. Floor response spectra of the structure should be sought for evaluating of the integrity of internal equipment. The floor response spectra depends on the characteristics of seismic base isolation system such as the natural frequency, damping ratio, and height of the floor of the structure. An evaluation of the structural integrity using the equivalent stiffness of the seismic base isolation system was satisfactory. In this study, the effect of the non-linearity of isolated system in the floor response spectrum of the structure is analyzed. In this study, the floor response spectrum of the seismic base isolation system by the non-linear effect of the rubber isolator was analyzed. As a result, the influence of the non-linear isolated system was increased in hi-frequency domain. In addition, each floor exhibited a more different of responses compared with the equivalent linear model of the isolated structure. The non-linearity of the isolation system of the structure was considered, because of a more reliable assessment of integrity of equipment at each floor of seismic base the isolation system.

  19. On the asymptotic behavior of solutions of certain third-order nonlinear differential equations

    Directory of Open Access Journals (Sweden)

    Cemil Tunç

    2005-01-01

    Full Text Available We establish sufficient conditions under which all solutions of the third-order nonlinear differential equation x ⃛+ψ(x,x˙,x¨x¨+f(x,x˙=p(t,x,x˙,x¨ are bounded and converge to zero as t→∞.

  20. Emergency control of unstable behavior of nonlinear systems induced by fault

    Directory of Open Access Journals (Sweden)

    Mark A. Pinsky

    1998-01-01

    -functions significantly simplifying analysis and control of fault phenomena. The design of an mergency controller is based on the technique for computing fault-induced jumps of the system states, which is described in the paper. An emergency controller instantaneously returning states of a sample nonlinear system to its stability basin is designed.

  1. Social Contagion, Adolescent Sexual Behavior, and Pregnancy: A Nonlinear Dynamic EMOSA Model.

    Science.gov (United States)

    Rodgers, Joseph Lee; Rowe, David C.; Buster, Maury

    1998-01-01

    Expands an existing nonlinear dynamic epidemic model of onset of social activities (EMOSA), motivated by social contagion theory, to quantify the likelihood of pregnancy for adolescent girls of different sexuality statuses. Compares five sexuality/pregnancy models to explain variance in national prevalence curves. Finds that adolescent girls have…

  2. Understanding bulk behavior of particulate materials from particle scale simulations

    Science.gov (United States)

    Deng, Xiaoliang

    Particulate materials play an increasingly significant role in various industries, such as pharmaceutical manufacturing, food, mining, and civil engineering. The objective of this research is to better understand bulk behaviors of particulate materials from particle scale simulations. Packing properties of assembly of particles are investigated first, focusing on the effects of particle size, surface energy, and aspect ratio on the coordination number, porosity, and packing structures. The simulation results show that particle sizes, surface energy, and aspect ratio all influence the porosity of packing to various degrees. The heterogeneous force networks within particle assembly under external compressive loading are investigated as well. The results show that coarse-coarse contacts dominate the strong network and coarse-fine contacts dominate the total network. Next, DEM models are developed to simulate the particle dynamics inside a conical screen mill (comil) and magnetically assisted impaction mixer (MAIM), both are important particle processing devices. For comil, the mean residence time (MRT), spatial distribution of particles, along with the collision dynamics between particles as well as particle and vessel geometries are examined as a function of the various operating parameters such as impeller speed, screen hole size, open area, and feed rate. The simulation results can help better understand dry coating experimental results using comil. For MAIM system, the magnetic force is incorporated into the contact model, allowing to describe the interactions between magnets. The simulation results reveal the connections between homogeneity of mixture and particle scale variables such as size of magnets and surface energy of non-magnets. In particular, at the fixed mass ratio of magnets to non-magnets and surface energy the smaller magnets lead to better homogeneity of mixing, which is in good agreement with previously published experimental results. Last but not

  3. Effects of bituminous layer as backfill material on mechanical behavior in tunnel model

    OpenAIRE

    Moriyoshi, Akihiro; Takano, Shin-ei; Urata, Hiroyuki; Suzuki, Tetsuya; Yoshida, Takaki

    2001-01-01

    This paper describes the effects of bituminous material as a backfill material on mechanical behavior in model tunnel in laboratory. It is known that load spreading and relaxation of bituminous material are good properties. Then if we use bituminous material as a backfill material of tunnel, the tunnel will have waterproof, good load spreading property. We used new bituminous material (Aquaphalt) which can solidify in water. We conducted relaxation test in tension for new bituminous mat...

  4. On the Anionic Group Approximation to the Borate Nonlinear Optical Materials

    Directory of Open Access Journals (Sweden)

    Rukang Li

    2017-02-01

    Full Text Available In this mini-review type of article, a brief summary of the anionic group approximation as it relates to the borate nonlinear optical (NLO crystals, an idea firstly proposed by Professor Chen, is presented.The basic idea, calculation method, tabulated coefficients of various common borate, as well as nitrate or carbonate groups, in their ideal geometries will be presented. New practices reveal that those parameters can still give very accurate predicted NLO coefficients for recently found NLO crystals without any adjustment of parameters.

  5. Thermal and Transmission Properties of UV Nonlinear Optical Material-- ZnCd(SCN)4 Crystal

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Zinc cadmium thiocyanate(ZCTC), ZnCd(SCN)4, has been discovered as a UV second-order nonlinear optical coordination crystal. Its thermal and transmission properties are reported. The thermal decomposition is characterized by using the X-ray powder diffraction (XRPD) and infrared (IR) spectroscopy at room temperature. The absorptions of intrinsic ions and ZCTC in a solution state are discussed as well as transmission properties of the ZCTC crystal. An effective method of reducing the surface reflection loss of ZCTC crystal is introduced.

  6. An Approximate Method for Analysis of Solitary Waves in Nonlinear Elastic Materials

    Science.gov (United States)

    Rushchitsky, J. J.; Yurchuk, V. N.

    2016-05-01

    Two types of solitary elastic waves are considered: a longitudinal plane displacement wave (longitudinal displacements along the abscissa axis of a Cartesian coordinate system) and a radial cylindrical displacement wave (displacements in the radial direction of a cylindrical coordinate system). The basic innovation is the use of nonlinear wave equations similar in form to describe these waves and the use of the same approximate method to analyze these equations. The distortion of the wave profile described by Whittaker (plane wave) or Macdonald (cylindrical wave) functions is described theoretically

  7. Photochemical stability of nonlinear optical chromophores in polymeric and crystalline materials.

    Science.gov (United States)

    Rezzonico, Daniele; Kwon, Seong-Ji; Figi, Harry; Kwon, O-Pil; Jazbinsek, Mojca; Günter, Peter

    2008-03-28

    We compare the photochemical stability of the nonlinear optical chromophore configurationally locked polyene 2-{3-[2-(4-dimethylaminophenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene} malononitrile (DAT2) embedded in a polymeric matrix and in a single-crystalline configuration. The results show that, under resonant light excitations, the polymeric compound degrades through an indirect process, while the DAT2 crystal follows a slow direct process. We show that chromophores in a crystalline environment exhibit three orders of magnitude better photostability as compared to guest-host polymer composites.

  8. L-Histidinium thiocyanurate: Experimental and theoretical studies of a new nonlinear optical material

    Science.gov (United States)

    Pereira Gonçalves, Mauro A.; Silva, Pedro S. Pereira; Silva, Manuela Ramos; Paixão, José A.

    2017-02-01

    A new organic compound, L-histidinium thiocyanurate thiocyanuric acid dihydrate, has been synthesized and characterized by single crystal X-ray diffraction, infrared spectroscopy and nonlinear optical measurements. The efficiency of the second-harmonic generation was evaluated with the Kurtz and Perry powder method at a fundamental wavelength of 1064 nm. By using the experimental structure, the molecular first hyperpolarizability tensor was determined with Hartree-Fock and density functional theory methods. The second-order susceptibility tensor of the crystal was evaluated using the oriented gas model with the Lorenz-Lorentz and the Wortmann-Bishop local-field corrections.

  9. Non-Linear Optical Phenomena in Detecting Materials as a Possibility for Fast Timing in Detectors of Ionizing Radiation

    CERN Document Server

    Korjik, M. V.; Buganov, O.; Fedorov, A. A.; Emelianchik, I.; Griesmayer, E.; Mechinsky, V.; Nargelas, S.; Sidletskiy, O.; Tamulaitis, G.; Tikhomirov, S. N.; Vaitkevicius, A.

    2016-01-01

    The time resolution of the detectors currently in use is limited by 50-70 ps due to the spontaneous processes involved in the development of the response signal, which forms after the relaxation of carriers generated during the interaction. In this study, we investigate the feasibility of exploiting sub-picosecond phenomena occurring after the interaction of scintillator material with ionizing radiation by probing the material with ultra-short laser pulses. One of the phenomena is the elastic polarization due to the local lattice distortion caused by the displacement of electrons and holes generated by ionization. The key feature of the elastic polarization is its short response time, which makes it prospective for using as an optically detectable time mark. The nonlinear optical absorption of femtosecond light pulses of appropriate wavelength is demonstrated to be a prospective tool to form the mark. This study was aimed at searching for inorganic crystalline media combining scintillation properties and non-...

  10. Tightness and Material Aspects of Bolted Flange Connections With Gaskets of Nonlinear Properties Exposed to Variable Loads

    Directory of Open Access Journals (Sweden)

    Walczak R.

    2016-09-01

    Full Text Available The paper presents the problems regarding bolted flange connections with gaskets used in chemical, petrochemical and energy industry. The aim of the research is to present state of knowledge regarding pipelines and apparatus in industrial installations and rules and regulations regarding flange connections tightness. Additionally a calculation example regarding flange connection according to ASME VIII DIV 1 requirement and then detailed Finite Element Analysis presented; impact of nonlinear material properties (gasket loading unloading curves on the connection tightness for complex loading programme is shown. It is finally concluded that in addition to usual design calculations more precise calculation is needed to fully verify behaviour of sealed connection at complex extreme variable loadings. Material aspect is very important at designing, testing, service and maintenance; taking it into consideration may avoid many problems related to safe exploitation.

  11. Nonlinear Dynamics and Bifurcation Behavior of a 2-DOF Spring Resonator with End Stopper for Energy Harvesting

    Directory of Open Access Journals (Sweden)

    El Aroudi A.

    2014-01-01

    Full Text Available In this paper, the model of a two-degree-of-freedom (2-DOF spring resonator with end stopper for an energy harvesting application is presented. Then we characterize its nonlinear dynamical behavior by numerical simulations when some suitable parameters are varied. The system is formed by two resonators subject to external vibrational excitation and with an end stopper. We present the continuous time dynamical model of the system in the form of a switched fourth order differential equation. Harmonic vibrations are considered as the main ambient energy source for the system and its frequency response representing the RMS value of the displacement is first computed. The dynamical behavior is unveiled by computing state-space trajectories, timedomain series and FFT spectra and frequency response as the excitation amplitude is varied.

  12. Issues associated with the use of Yoshida nonlinear isotropic/kinematic hardening material model in Advanced High Strength Steels

    Science.gov (United States)

    Shi, Ming F.; Zhang, Li; Zhu, Xinhai

    2016-08-01

    The Yoshida nonlinear isotropic/kinematic hardening material model is often selected in forming simulations where an accurate springback prediction is required. Many successful application cases in the industrial scale automotive components using advanced high strength steels (AHSS) have been reported to give better springback predictions. Several issues have been raised recently in the use of the model for higher strength AHSS including the use of two C vs. one C material parameters in the Armstrong and Frederick model (AF model), the original Yoshida model vs. Original Yoshida model with modified hardening law, and constant Young's Modulus vs. decayed Young's Modulus as a function of plastic strain. In this paper, an industrial scale automotive component using 980 MPa strength materials is selected to study the effect of two C and one C material parameters in the AF model on both forming and springback prediction using the Yoshida model with and without the modified hardening law. The effect of decayed Young's Modulus on the springback prediction for AHSS is also evaluated. In addition, the limitations of the material parameters determined from tension and compression tests without multiple cycle tests are also discussed for components undergoing several bending and unbending deformations.

  13. Etching, micro hardness and laser damage threshold studies of a nonlinear optical material L-valine

    Science.gov (United States)

    Anbuchezhiyan, M.; Ponnusamy, S.; Muthamizhchelvan, C.; Kanakam, C. C.; Singh, S. P.; Pal, P. K.; Datta, P. K.

    2012-04-01

    A nonlinear optical crystal of L-valine was grown from an aqueous solution containing a small amount of phosphoric acid by the slow evaporation method. The grown crystal was characterized by a single crystal X-ray diffraction to determine the unit cell parameters. The powder X-ray diffraction analysis also confirmed the lattice parameters to be a = 9.6687(7) Å, b = 5.2709(4) Å, c = 12.0371(10) Å and β = 90.805(4)°. The results of the Inductively Coupled Plasma Optical Emission Spectrometry (ICPOES) indicate the presence of a small amount of phosphorus in the grown crystal. The Vickers micro hardness test was performed to study the mechanical strength of the crystals. Chemical etching studies were carried out to analyze the dislocation structure. The laser damaged threshold of the grown crystal was measured to be 11.11 GW/cm2 for 10 ns pulse at 1064 nm, which is higher than that of the standard nonlinear optical crystals like KDP. Second harmonic generation of the grown crystals was also 1.44 times that of KDP.

  14. Modeling the Non-Linear Behavior of Library Cells for an Accurate Static Noise Analysis

    CERN Document Server

    Forzan, Cristiano

    2011-01-01

    In signal integrity analysis, the joint effect of propagated noise through library cells, and of the noise injected on a quiet net by neighboring switching nets through coupling capacitances, must be considered in order to accurately estimate the overall noise impact on design functionality and performances. In this work the impact of the cell non-linearity on the noise glitch waveform is analyzed in detail, and a new macromodel that allows to accurately and efficiently modeling the non-linear effects of the victim driver in noise analysis is presented. Experimental results demonstrate the effectiveness of our method, and confirm that existing noise analysis approaches based on linear superposition of the propagated and crosstalk-injected noise can be highly inaccurate, thus impairing the sign-off functional verification phase.

  15. Solitonic and chaotic behaviors for the nonlinear dust-acoustic waves in a magnetized dusty plasma

    Science.gov (United States)

    Zhen, Hui-Ling; Tian, Bo; Xie, Xi-Yang; Wu, Xiao-Yu; Wen, Xiao-Yong

    2016-05-01

    A model for the nonlinear dust-ion-acoustic waves in a two-ion-temperature, magnetized dusty plasma is studied in this paper. Via the symbolic computation, one-, two- and N-soliton solutions are obtained. It is found that when √{μeμi }parallel during the propagation on the x - y, x - t, and y - t planes, where x, y, and z are the scaled spacial coordinates, and t is the retarded time. Upon the introduction of the driving force Γ(t ) , both the developed and weak chaotic motions as well as the effect of Γ(t ) are explored. Via the phase projections and power spectra, we find the difference between the two chaotic motions roots in the relative magnitude of nonlinearity and external force. Increasing the frequency of the external force or the strength of the damped term can weaken the chaotic motions of such a forced model.

  16. The effect of process delay on dynamical behaviors in a self-feedback nonlinear oscillator

    Science.gov (United States)

    Yao, Chenggui; Ma, Jun; Li, Chuan; He, Zhiwei

    2016-10-01

    The delayed feedback loops play a crucial role in the stability of dynamical systems. The effect of process delay in feedback is studied numerically and theoretically in the delayed feedback nonlinear systems including the neural model, periodic system and chaotic oscillator. The process delay is of key importance in determining the evolution of systems, and the rich dynamical phenomena are observed. By introducing a process delay, we find that it can induce bursting electric activities in the neural model. We demonstrate that this novel regime of amplitude death also exists in the parameter space of feedback strength and process delay for the periodic system and chaotic oscillator. Our results extend the effect of process delay in the paper of Zou et al.(2013) where the process delay can eliminate the amplitude death of the coupled nonlinear systems.

  17. Nonlinear dynamic behaviors of clamped laminated shallow shells with one-to-one internal resonance

    Science.gov (United States)

    Abe, Akira; Kobayashi, Yukinori; Yamada, Gen

    2007-07-01

    This paper investigates one-to-one internal resonance of laminated shallow shells with rigidly clamped edges. It is assumed that the natural frequencies ω2 and ω3 of two asymmetric (second and third) vibration modes have the relationship ω2≈ ω3. The displacements are expressed by using eigenvectors for linear vibration modes calculated by the Ritz method. Applying Galerkin's procedure to the equation of motion, nonlinear differential equations are derived. By considering the first vibration mode in addition to the two asymmetric vibration modes, quadratic nonlinear terms expressing the interaction between the asymmetric and the first modes appear in the differential equations. Shooting method is used to obtain the steady-state response when the driving frequency Ω is near ω2. The dynamic characteristics of the shells with the internal resonance are discussed.

  18. Long-time behavior of a class of thermoelastic plates with nonlinear strain

    Science.gov (United States)

    Fatori, L. H.; Jorge Silva, M. A.; Ma, T. F.; Yang, Zhijian

    2015-11-01

    In recent years a class of vibrating plates with nonlinear strain of p-Laplacian type was studied by several authors. The present paper contains a first thermoelastic model of that class of problems including both Fourier and non-Fourier heat laws. Our main result establishes the existence of global and exponential attractors for the strongly damped problem through a stabilizability inequality. In addition, for the weakly damped problem, we establish the exponential stability of its Galerkin semiflows.

  19. LARGE TIME BEHAVIOR OF SOLUTIONS TO NONLINEAR VISCOELASTIC MODEL WITH FADING MEMORY

    Institute of Scientific and Technical Information of China (English)

    Yanni Zeng

    2012-01-01

    We study the Cauchy problem of a one-dimensional nonlinear viscoelastic model with fading memory. By introducing appropriate new variables we convert the integro-partial differential equations into a hyperbolic system of balance laws.When it is a perturbation of a constant state,the solution is shown time asymptotically approaching to predetermined diffusion waves.Pointwise estimates on the convergence details are obtained.

  20. Linear and Nonlinear Behavior Analysis of a Flexible Shaft Supported By Hydrostatic Squeeze Film Dampers

    Directory of Open Access Journals (Sweden)

    A. Bouzidane

    2014-01-01

    Full Text Available Linear and non linear models of a hydrostatic squeeze film damper are presented and numerically simulated by a step by step method on a modal basis, in order to study the non-linear dynamic behaviour of a flexible shaft. The Reynolds equation is solved at each step in order to evaluate the film forces. The equations of motion are then integrated by using the Newmark method with a variable step in order to obtain speeds and the position for the next step. The non-linear hydrostatic forces are determined by the application of the boundary conditions, and the integration of the pressure field is determined by resolution of Reynolds equation, by applying the central finite difference method. The aim of this research is to study the effect of pressure ratio, viscosity, and rotational speeds on the vibratory responses and the transmitted bearing forces. The results are discussed, analysed and compared to a linear approach which is restricted to only small vibrations around the equilibrium position. The results show good agreements between linear and non-linear methods when the unbalance force is small, and then the linear model may be used for small vibrations in order to reduce compilation time during the iterative process.

  1. Nonlinear flexural waves and chaos behavior in finite-deflection Timoshenko beam

    Institute of Scientific and Technical Information of China (English)

    Shan-yuan ZHANG; Zhi-fang LIU

    2010-01-01

    Based on the Timoshenko beam theory,the finite-deflection and the axial inertia are taken into account,and the nonlinear partial differential equations for flexural waves in a beam are derived. Using the traveling wave method and integration skills,the nonlinear partial differential equations can be converted into an ordinary differential equation. The qualitative analysis indicates that the corresponding dynamic system has a heteroclinic orbit under a certain condition. An exact periodic solution of the nonlinear wave equation is obtained using the Jacobi elliptic function expansion. When the modulus of the Jacobi elliptic function tends to one in the degenerate case,a shock wave solution is given. The small perturbations are further introduced,arising from the damping and the external load to an original Hamilton system,and the threshold condition of the existence of the transverse heteroclinic point is obtained using Melnikov's method. It is shown that the perturbed system has a chaotic property under the Smale horseshoe transform.

  2. Research on strip hysteretic behavior and mill vertical vibration system nonlinear dynamics

    Science.gov (United States)

    Fan, Xiaobin; Zang, Yong; Jin, Ke

    2016-10-01

    Rolling mill vibration is a technical problem in the iron and steel industry for many years and has serious impact and harm on production. There were serious vibrations in the middle mills when rolling thin container strip for the compact strip production (CSP) strip hot rolling process. This paper studied the hysteretic characteristic of rolled strip and established the vertical vibration system single-degree-of-freedom dynamics model of the F3 mill rollers. The influence of parameters on the system characteristics was studied, such as the linear damping coefficient, linear stiffness coefficient, nonlinear displacement coefficient, nonlinear velocity coefficient and exciting force, and then, the vibration source and vibration-restraining measure were studied from the roll gap. The results show that with increasing linear stiffness, damping and hysteresis coefficient, it can reduce the possibility of chaotic system; the linear stiffness coefficient had the greatest influence, and hysteresis damping coefficient had minimal influence on chaotic threshold. In order to reduce rolling mill vibration amplitude, we should reduce the external excitation force firstly, and in order to improve the dynamic performance of the system, we should control the speed of nonlinear coefficient values. The contrast experiments were carried out at the production scene finally.

  3. Adsorption Behavior of Potassium Ion on Planting Materials

    Institute of Scientific and Technical Information of China (English)

    PAUNPASSANAN,Dechprasitthichoke; SUNANTA,Wangkarn; SAKDIPHON,Thiansem; PONLAYUTH,Sooksamiti; ORN-ANONG,Arquero

    2007-01-01

    Characterization of planting materials used as adsorbent has been studied in order to compare potassium ion adsorption on two types of planting materials, which are a fired planting material (FPM) made from a mixture of 4 kinds of wastes (bottom ash, flue gas desulfurization (FGD) gypsum, paddy soil and sawdust) formed and fired at 850 ℃ and the commercial planting material called "hydroball" (HDB) bought from Jatujak market, Bangkok. The physical characteristics of both types of planting materials indicate that the FPM has a larger specific surface area than the HDB. The factors affecting potassium adsorption on both the planting materials such as an equilibration time and some solid/solution ratios were investigated. The suitable equilibration time for the adsorption to reach an equilibrium on the FPM and HDB is one and two hours, respectively. The highest amounts of potassium ion adhavior on both the planting materials tends to correspond with the Freundlich isotherm.

  4. Nonlinear I-V characteristics of nanoparticle compacts and nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Herth, Simone [Rensselaer Polytechnic Institute, Troy, NY (United States); Bielefeld University, Bielefeld (Germany); Wang, Xiaoping; Hugener, Teresa; Schadler, Linda; Siegel, Richard [Rensselaer Polytechnic Institute, Troy, NY (United States); Hillborg, Henrik; Auletta, Tommaso [ABB AB, Corporate Research, Schweden (Sweden)

    2007-07-01

    Materials with nonlinear I-V characteristics are commonly used as field grading materials. In many cases, the non-linearity is achieved through the addition of equiaxed fillers to a polymer matrix. These composite field grading materials are optimized in terms of nonlinearity, conductivity, and breakdown strength. One limitation in designing new field grading materials is a robust understanding of the relationship between powder morphology, composition and electrical characteristics of the powder, as well as a robust understanding of the relationship between powder conductivity and non-linearity and composite non-linearity. In this work, treatment of ZnO powder with a SnF{sub 2} solution resulted in a powder that yielded highly non-linear behavior. The highest non-linearity was achieved for powders with at least two different phases and a rough surface, as indicated by transmission electron micrographs. In contrast, the non-linearity of the nanocomposite conductivity is mainly determined by the conductivity of the nanofiller. The electrical behavior of the non-linear powder can be understood by a polarization of the nanoparticles at the interfaces, whereas the nonlinearity of the nanocomposites can be explained by a tunnelling mechanism between two particles.

  5. Reformulation of Nonlinear Anisotropic Crystal Elastoplasticity for Impact Physics

    Science.gov (United States)

    2015-03-01

    JD. Modeling nonlinear electromechanical behavior of shocked silicon carbide. Journal of Applied Physics . 2010;107:013520. 30. Clayton JD. A... Physics by JD Clayton Approved for public release; distribution unlimited. NOTICES Disclaimers...of Nonlinear Anisotropic Crystal Elastoplasticity for Impact Physics by JD Clayton Weapons and Materials Research Directorate, ARL

  6. BaGa2MQ6 (M = Si, Ge; Q = S, Se): a new series of promising IR nonlinear optical materials.

    Science.gov (United States)

    Yin, Wenlong; Feng, Kai; He, Ran; Mei, Dajiang; Lin, Zheshuai; Yao, Jiyong; Wu, Yicheng

    2012-05-14

    The four compounds BaGa(2)MQ(6) (M = Si, Ge; Q = S, Se) have been identified as a new series of IR nonlinear optical (NLO) materials and are promising for practical applications. They are isostructural and crystallize in the noncentrosymmetric polar space group R3 of the trigonal system. Their three-dimensional framework is composed of corner-sharing (Ga/M)Q(4) (M = Si, Ge; Q = S, Se) tetrahedra with Ba(2+) cations in the cavities. The polar alignment of one (Ga/M)-Q2 bond for each (Ga/M)Q(4) tetrahedra along the c direction is conducive to generating a large NLO response, which was confirmed by powder second-harmonic generation (SHG) using a 2090 nm laser as fundamental wavelength. The SHG signal intensities of the two sulfides were close to that of AgGaS(2) and those for the two selenides were similar as that of AgGaSe(2). The large band gaps of 3.75(2) eV, 3.23(2) eV, 2.88(2) eV, and 2.22 (2) eV for BaGa(2)SiS(6), BaGa(2)GeS(6), BaGa(2)SiSe(6), and BaGa(2)GeSe(6), respectively, will be very helpful to increase the laser damage threshold. Moreover, all the four BaGa(2)MQ(6) (M = Si, Ge; Q = S, Se) compounds exhibit congruent-melting behavior, which indicates that bulk crystals needed for practical applications can be obtained by the Bridgman-Stockbarger method. The calculated birefringence indicates that these materials may be phase-matchable in the IR region and the calculated SHG coefficients agree with the experimental observations. According to our preliminary study, the BaGa(2)MQ(6) compounds represent a new series of promising IR nonlinear optical (NLO) materials which do not belong to the traditional chalcopyrite-type materials such as AgGaQ2 (Q = S, Se) and ZnGeP(2).

  7. Nonlinear optics

    CERN Document Server

    Boyd, Robert W

    2013-01-01

    Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q

  8. Exciton Dynamics and Many Body Interactions in Layered Semiconducting Materials Revealed with Non-linear Coherent Spectroscopy

    Science.gov (United States)

    Dey, Prasenjit

    understanding the basic unexplored science as well as creating technological developments. The dephasing dynamics in semiconductors typically occur in the picosecond to femtosecond timescale, thus the use of ultrafast laser spectroscopy is a potential route to probe such excitonic responses. The focus of this dissertation is two-fold: firstly, to develop the necessary instrumentation to accurately probe the aforementioned parameters and secondly, to explore the quantum dynamics and the underlying many-body interactions in different layered semiconducting materials. A custom-built multidimensional optical non-linear spectrometer was developed in order to perform two-dimensional spectroscopic (2DFT) measurements. The advantages of this technique are multifaceted compared to regular one-dimensional and non-linear incoherent techniques. 2DFT technique is based on an enhanced version of Four wave mixing experiments. This powerful tool is capable of identifying the resonant coupling, probing the coherent pathways, unambiguously extracting the homogeneous linewidth in the presence of inhomogeneity and decomposing a complex spectra into real and imaginary parts. It is not possible to uncover such crucial features by employing one dimensional non-linear technique. Monolayers as well as bulk TMDs and group III-VI bulk layered materials are explored in this dissertation. The exciton quantum dynamics is explored with three pulse four-wave mixing whereas the phase sensitive measurements are obtained by employing two-dimensional Fourier transform spectroscopy. Temperature and excitation density dependent 2DFT experiments unfold the information associated with the many-body interactions in the layered semiconducting samples.

  9. Modeling and characterization of the elastic behavior of interfaces in nanostructured materials: From an atomistic description to a continuum approach

    Science.gov (United States)

    Dingreville, Remi

    the effects of surface free energy on the effective modulus of nano-particles, nano-wires and nano-films as well as nanostructured crystalline materials and propose a general framework valid for any shape of nanostructural elements/nano-inclusions (integral forms) that characterizes the size-dependency of the elastic properties. This approach bridges the gap between discrete systems (atomic level interactions) and continuum mechanics. Finally this continuum outline is used to understand the effects of surfaces on the overall behavior of nano-size structural elements (particles, films, fibers, etc.) and nanostructured materials. More specifically we will discuss the impact of surface relaxation, surface elasticity and non-linearity of the underlying bulk on the properties nanostructured materials. In terms of engineering applications, this approach proves to be a useful tool for multi-scale modeling of heterogeneous materials with nanometer scale microstructures and provides insights on surface properties for several material systems; these will be very useful in many fields including surface science, tribology, fracture mechanics, adhesion science and engineering, and more. It will accelerate the insertion of nano-size structural elements, nano-composite and nanocrystalline materials into engineering applications.

  10. Model for nonlinear behavior in the self-amplified spontaneous-emission free-electron laser

    Science.gov (United States)

    Krinsky, S.

    2004-06-01

    We introduce a simplified model for the saturation of a self-amplified spontaneous-emission free-electron laser. Within this model, we determine the effect of nonlinearity upon the statistical properties of the output radiation. Comparing our results with the computer simulations of Saldin, Schneidmiller, and Yurkov [The Physics of Free Electron Lasers (Springer-Verlag, Berlin, 2000)], we find that the model provides a good description of the average intensity, field correlation function, and coherence time, but underestimates the intensity fluctuation. Asymmetric spectral broadening phenomena are not included in the model.

  11. Nonlinear Constitutive Equation for Green Sand Considering the Tri-axial Compression Behavior

    Institute of Scientific and Technical Information of China (English)

    曾攀; 孔劲

    2004-01-01

    The compression characteristics of green sand were investigated experimentally, including the squeezing and yielding during deformation. An expression was developed for the transient compression modulus of sand during compression. Based on the hypothesis put forward of the compression state, the differential equation for the nonlinear constitutive equation was deduced by introducing a move-yield potential function. The state constitutive equation under the tri-axial experiment is further studied according to the sand attributes, considering the differential form of Hooke's law and the Mohr-Coulomb condition. The related experiment data are applied to verify the proposed constitutive model of sand.

  12. On tail behavior of nonlinear autoregressive functional conditional heteroscedastic model with heavy-tailed innovations

    Institute of Scientific and Technical Information of China (English)

    PAN; Jiazhu; WU; Guangxu

    2005-01-01

    We study the tail probability of the stationary distribution of nonparametric nonlinear autoregressive functional conditional heteroscedastic (NARFCH) model with heavytailed innovations. Our result shows that the tail of the stationary marginal distribution of an NARFCH series is heavily dependent on its conditional variance. When the innovations are heavy-tailed, the tail of the stationary marginal distribution of the series will become heavier or thinner than that of its innovations. We give some specific formulas to show how the increment or decrement of tail heaviness depends on the assumption on the conditional variance function. Some examples are given.

  13. Nonlinear oscillations of laminated plates using an accurate four-node rectangular shear flexible material finite element

    Indian Academy of Sciences (India)

    Gajbir Singh; G Venkateswara Rao

    2000-08-01

    The objective of the present paper is to investigate the large amplitude vibratory behaviour of unsymmetrically laminated plates. For this purpose, an efficient and accurate four-node shear flexible rectangular material finite element(MFE) with six degrees offreedom per node (three displacements $(u;v;w)$ along the $x, y$ and axes, two rotations ($\\theta_x$ and $\\theta_y$) about and axes and twist $(\\theta_{xy})$) is developed. The element assumes bi-cubic polynomial distribution with sixteen generalized undetermined coefficients for the transverse displacement. The fields for section rotations $\\theta_x$ and $\\theta_y$, and in-plane displacements and are derived using moment-shear equilibrium and in-plane equilibrium equations of composite strips along the - and -axes. The displacement field so derived not only depends on the element coordinates but is a function of extensional, bending-extensional coupling, bending and transverse shear stiffness as well. The element stiffness and mass matrices are computed numerically by employing 3 × 3 Gauss-Legendre product rules. The element is found to be free of shear locking and does not exhibit any spurious modes. In orderto compute the nonlinearfrequencies, linear mode shape corresponding to the fundamental frequency is assumed as the spatial distribution and nonlinear finite element equations are reduced to a single nonlinear second-order differential equation. This equation is solved by employing the direct numerical integration method. A series of numerical examples are solved to demonstrate the efficacy of the proposed element.

  14. Fundamental-Solution-Based Hybrid Element Model for Nonlinear Heat Conduction Problems with Temperature-Dependent Material Properties

    Directory of Open Access Journals (Sweden)

    Hui Wang

    2013-01-01

    Full Text Available The boundary-type hybrid finite element formulation coupling the Kirchhoff transformation is proposed for the two-dimensional nonlinear heat conduction problems in solids with or without circular holes, and the thermal conductivity of material is assumed to be in terms of temperature change. The Kirchhoff transformation is firstly used to convert the nonlinear partial differential governing equation into a linear one by introducing the Kirchhoff variable, and then the new linear system is solved by the present hybrid finite element model, in which the proper fundamental solutions associated with some field points are used to approximate the element interior fields and the conventional shape functions are employed to approximate the element frame fields. The weak integral functional is developed to link these two fields and establish the stiffness equation with sparse and symmetric coefficient matrix. Finally, the algorithm is verified on several examples involving various expressions of thermal conductivity and existence of circular hole, and numerical results show good accuracy and stability.

  15. Viscoelastic materials with anisotropic rigid particles: stress-deformation behavior

    NARCIS (Netherlands)

    Sagis, L.M.C.; Linden, van der E.

    2001-01-01

    In this paper we have derived constitutive equations for the stress tensor of a viscoelastic material with anisotropic rigid particles. We have assumed that the material has fading memory. The expressions are valid for slow and small deformations from equilibrium, and for systems that are nearly

  16. Nonlinear electrostatic drift Kelvin-Helmholtz instability

    Science.gov (United States)

    Sharma, Avadhesh C.; Srivastava, Krishna M.

    1993-01-01

    Nonlinear analysis of electrostatic drift Kelvin-Helmholtz instability is performed. It is shown that the analysis leads to the propagation of the weakly nonlinear dispersive waves, and the nonlinear behavior is governed by the nonlinear Burger's equation.

  17. A natural neighbour method based on Fraeijs de Veubeke variational principle for materially non-linear problems

    Institute of Scientific and Technical Information of China (English)

    Xiang Li; Serge Cescotto; Barbara Rossi

    2009-01-01

    The natural neighbour method can be considered as one of many variants of the meshless methods. In the present paper, a new approach based on the Fraeijs de Veubeke (FdV) functional, which is initially developed for linear elasticity, is extended to the case of geometrically linear but materially non-linear solids. The new approach provides an original treatment to two classical problems: the numerical evaluation of the integrals over the domain A and the enforcement of boundary conditions of the type ui = uion Su. In the absence of body forces (Fi = 0), it will be shown that the calculation of integrals of the type fA .dA can be avoided and that boundary conditions of the type ui = ui on Su can be imposed in the average sense in general and exactly if ui is linear between two contour nodes, which is obviously the case for ui = 0.

  18. Springback Analysis in Sheet Metal Forming of Non-linear Work-Hardening material Under Pure Bending

    Science.gov (United States)

    Lal, Radha Krishna; Dwivedi, Jai Prakash; Bhagat, Manish Kumar; Singh, Virendra Pratap

    2016-09-01

    This paper deals with the springback analysis in sheet metal forming for non-linear work-hardening material under pure bending. Using the deformation theory of plasticity, formulation of the problem and spring back ratio is derived using Ramberg-Osgood stress strain relationship with Tresca and Von-Mises yielding criteria. The results have been representing the effect of different value of Y/E or σo/E ratio, different values of strain hardening index (n), Poisson's ratio (ν) and thickness on springback ratio (R0/Rf). The main aim of this paper is to study the effects of the thickness, Y/E ratio, n and Poisson's ratio in spring back ratio.

  19. Monitoring and analysis of nonlinear dynamic damage of transport roadway supported by composite hard rock materials in Linglong Gold Mine

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The study concentrates mainly on the development of failure process in composite rock mass. By use of acoustic emission(AE), convergence inspection, pressure monitoring, level measurement techniques and the modem signal analysis technology, as wellas scan electron microscopy (SEM) experiment, various aspects of nonlinear dynamic damage of composite rock mass surroundingthe transport roadway in Linglong gold mine are discussed. According to the monitoring results, the stability of the rock mass can besynthetically evaluated, and the intrinsic relation between the damage and the characteristic parameters of acoustic emission can bedetermined. The location of the damage of rock mass can also be detected based on the acoustic emission couple monitoring signals.Finally, the key factors which influence the stability of the transport roadway supported by composite hard rock materials are foundout.

  20. Synthesis of Novel Arylazothiazolyl-thiophene Dyes for Solar Cell and Nonlinear Optical Materials.

    Science.gov (United States)

    Khalifa, Mohamed E; Al-Amoudi, Muhammed S; Gobouri, Adil A; Merazga, Amar; Fadda, Ahmed A

    2016-01-01

    Synthesis and investigation of new donor-acceptor conjugated N-(5-arylazothiazol-2-yl)-2-aminothiophene derivatives with the aim to elucidate the contribution of their interaction with solvent molecules upon intramolecular charge transfer for their potential solar cells application. The UV-visible and emission spectra measurements indicated that the properties of the synthesized dyes had a significant effect on the visible absorption and emission maxima. The effect of the donor and acceptor groups were studied for the nonlinearity based on their HOMO-LUMO band gap energy. The dye-sensitized solar cells (DSSCs) were assembled by using the newly synthesized aryl thiazolyl-thiophene dyes as sensitizers. The promising results of J(SC) (2.46 × 10(-2) and 4.07 × 10(-2) mA/cm(2)), the V(OC) (0.429 V and 0.426 V) and the FF (0.66 %) values obtained comparing with other organic and natural sensitizer were due to the better interaction between the carboxyl and carbonyl groups of aryl azo molecule attached to the thiazolyl nucleus and the surface of TiO(2) porous film.