Loy, Ignacio; Fernández, Vanesa; Acebes, Félix
2006-08-01
In a series of related experiments, we studied associative phenomena in snails (Helix aspersa), using the conditioning procedure of tentacle lowering. Experiments 1A and 1B demonstrated a basic conditioning effect in which the pairing of an odor (apple) as the conditioned stimulus (CS) with the opportunity to feed on carrot as the unconditioned stimulus (US) made snails exhibit increased levels of tentacle lowering in the presence of the CS. Experiments 2 and 3 showed that the magnitude of the conditioning was reduced when snails were exposed to the CS prior to the conditioning trial (a latent inhibition effect). Experiment 4 examined the effects produced by pairing a compound CS (apple-pear) with food presentations and demonstrated the existence of an overshadowing effect between the two odors. Experiment 5 revealed that pairing one CS with another previously conditioned stimulus increased tentacle lowering to the new CS (a second-order conditioning effect). Finally, Experiment 6 showed that pairing two odors prior to conditioning of one of them promoted an increase in tentacle lowering in response to the other (a sensory preconditioning effect). The results are discussed in terms of an associative analysis of conditioning and its implications for the study of cognition in invertebrates.
Second order pedagogy as an example of second order cybernetics
Directory of Open Access Journals (Sweden)
Anne B. Reinertsen
2012-07-01
Full Text Available This article is about seeing/creating/trying out an idea of pedagogy and pedagogical/ educational research in/as/with self-reflexive, circular and diffractive perspectives and about using second order cybernetics as thinking tool. It is a move away from traditional hypothesis driven activities and a move towards data driven pedagogies and research: Teachers, teacher researchers and researchers simultaneously producing and theorizing our practices and ourselves. Deleuzian becomings- eventually becomings with data - theory - theodata is pivotal. It is a move towards a Derridean bricolage. A different science of pedagogy operating as a circular science of self-reflexivity and diffraction in search of quality again and again and again: Theopractical becomings and inspiractionresearch.
Metacommunication as Second Order Communication
Directory of Open Access Journals (Sweden)
Samuel Mateus
2017-07-01
Full Text Available By giving full emphasis to the impossibility of not to communicate, the first axiom of communication stresses how communication is an event not subject to cessation. It is this never-ending characteristic that impels us to the need to ponder on metacommunication as “communication about communication”. By taking a philosophically informed and pragmatic stance, this paper deals with the concept of “metacommunication” and tries to incorporate it in the theory of communication. It posits communication is a multilevel dialectical happening in which metacommunication presents itself a kind of second order communication. The paper describes communication as an ad infinitum process in which every communication supposes always more communication. Metacommunication is the answer to the relationship level of communication and that’s why we postulate metacommunication as a re-communicating communication.
Boolean-valued second-order logic
Ikegami, D.; Väänänen, J.
2015-01-01
In so-called full second-order logic, the second-order variables range over all subsets and relations of the domain in question. In so-called Henkin second-order logic, every model is endowed with a set of subsets and relations which will serve as the range of the second-order variables. In our
Second-Order Science of Interdisciplinary Research
DEFF Research Database (Denmark)
Alrøe, Hugo Fjelsted; Noe, Egon
2014-01-01
require and challenge interdisciplinarity. Problem: The conventional methods of interdisciplinary research fall short in the case of wicked problems because they remain first-order science. Our aim is to present workable methods and research designs for doing second-order science in domains where...... there are many different scientific knowledges on any complex problem. Method: We synthesize and elaborate a framework for second-order science in interdisciplinary research based on a number of earlier publications, experiences from large interdisciplinary research projects, and a perspectivist theory...... of science. Results: The second-order polyocular framework for interdisciplinary research is characterized by five principles. Second-order science of interdisciplinary research must: 1. draw on the observations of first-order perspectives, 2. address a shared dynamical object, 3. establish a shared problem...
Second Order Ideal-Ward Continuity
Directory of Open Access Journals (Sweden)
Bipan Hazarika
2014-01-01
Full Text Available The main aim of the paper is to introduce a concept of second order ideal-ward continuity in the sense that a function f is second order ideal-ward continuous if I-limn→∞Δ2f(xn=0 whenever I-limn→∞Δ2xn=0 and a concept of second order ideal-ward compactness in the sense that a subset E of R is second order ideal-ward compact if any sequence x=(xn of points in E has a subsequence z=(zk=(xnk of the sequence x such that I-limk→∞Δ2zk=0 where Δ2zk=zk+2-2zk+1+zk. We investigate the impact of changing the definition of convergence of sequences on the structure of ideal-ward continuity in the sense of second order ideal-ward continuity and compactness of sets in the sense of second order ideal-ward compactness and prove related theorems.
Systemic Design for Second-Order Effects
Directory of Open Access Journals (Sweden)
Evan Barba
2017-04-01
Full Text Available Second-order effects refer to changes within a system that are the result of changes made somewhere else in the system (the first-order effects. Second-order effects can occur at different spatial, temporal, or organizational scales from the original interventions, and are difficult to control. Some organizational theorists suggest that careful management of feedback processes can facilitate controlled change from one organizational configuration to another. Recognizing that skill in managing feedback processes is a core competency of design suggests that design skills are potentially useful tools in achieving organizational change. This paper describes a case study in which a co-design methodology was used to control the second-order effects resulting from a classroom intervention to create organizational change. This approach is then theorized as the Instigator Systems approach.
Second Order Mode Selective Phase-Matching
DEFF Research Database (Denmark)
Lassen, Mikael Østergaard; Delaubert, Vincent; Bachor, Hans. A-
2006-01-01
We exploit second order (χ(2)) nonlinear optical phase matching for the selection of individual high order transverse modes. The ratio between the generated components can be adjusted continuously via changes in the phase-matching condition. ©2007 Optical Society of America......We exploit second order (χ(2)) nonlinear optical phase matching for the selection of individual high order transverse modes. The ratio between the generated components can be adjusted continuously via changes in the phase-matching condition. ©2007 Optical Society of America...
Scintillation camera with second order resolution
International Nuclear Information System (INIS)
Muehllehner, G.
1976-01-01
A scintillation camera for use in radioisotope imaging to determine the concentration of radionuclides in a two-dimensional area is described in which means is provided for second order positional resolution. The phototubes, which normally provide only a single order of resolution, are modified to provide second order positional resolution of radiation within an object positioned for viewing by the scintillation camera. The phototubes are modified in that multiple anodes are provided to receive signals from the photocathode in a manner such that each anode is particularly responsive to photoemissions from a limited portion of the photocathode. Resolution of radioactive events appearing as an output of this scintillation camera is thereby improved
Second-Order Conditioning in "Drosophila"
Tabone, Christopher J.; de Belle, J. Steven
2011-01-01
Associative conditioning in "Drosophila melanogaster" has been well documented for several decades. However, most studies report only simple associations of conditioned stimuli (CS, e.g., odor) with unconditioned stimuli (US, e.g., electric shock) to measure learning or establish memory. Here we describe a straightforward second-order conditioning…
Nine Practices of Second Order Schools
Brown, Bill; Tucker, Patrick; Williams, Thomas L.
2012-01-01
Many schools are in some stage of implementing differentiated instruction, with some already in what Carol Tomlinson describes in "The Differentiated School" as "second order change," where the entire school practices differentiation. In high-performing schools, differentiation has proved to be an effective instructional strategy; in classroom…
Second order evolution equations with nonlocal conditions
Directory of Open Access Journals (Sweden)
Benchohra Mouffak
2017-12-01
Full Text Available In this paper, we shall establish sufficient conditions for the existence of solutions for second order semilinear functional evolutions equation with nonlocal conditions in Fréchet spaces. Our approach is based on the concepts of Hausdorff measure, noncompactness and Tikhonoff’s fixed point theorem. We give an example for illustration.
Second-order gravitational self-force
International Nuclear Information System (INIS)
Rosenthal, Eran
2006-01-01
We derive an expression for the second-order gravitational self-force that acts on a self-gravitating compact object moving in a curved background spacetime. First we develop a new method of derivation and apply it to the derivation of the first-order gravitational self-force. Here we find that our result conforms with the previously derived expression. Next we generalize our method and derive a new expression for the second-order gravitational self-force. This study also has a practical motivation: The data analysis for the planned gravitational wave detector LISA requires construction of waveform templates for the expected gravitational waves. Calculation of the two leading orders of the gravitational self-force will enable one to construct highly accurate waveform templates, which are needed for the data analysis of gravitational waves that are emitted from extreme mass-ratio binaries
Second order Horner's syndrome in a cat.
De Risio, Luisa; Fraser McConnell, James
2009-08-01
This case report describes the clinical and magnetic resonance imaging (MRI) findings of a 3.5-year-old, male neutered, domestic shorthair cat with second order Horner's syndrome as the only clinical abnormality. The neuroanatomical pathway of the sympathetic innervation to the eye, differential diagnoses for Horner's syndrome in cats, and the interpretation of pharmacological testing are reviewed. The unusual MRI findings and the value of fat-suppressed MRI sequences are discussed.
Second Order Optimality in Markov Decision Chains
Czech Academy of Sciences Publication Activity Database
Sladký, Karel
2017-01-01
Roč. 53, č. 6 (2017), s. 1086-1099 ISSN 0023-5954 R&D Projects: GA ČR GA15-10331S Institutional support: RVO:67985556 Keywords : Markov decision chains * second order optimality * optimalilty conditions for transient, discounted and average models * policy and value iterations Subject RIV: BB - Applied Statistics, Operational Research OBOR OECD: Statistics and probability Impact factor: 0.379, year: 2016 http://library.utia.cas.cz/separaty/2017/E/sladky-0485146.pdf
Frankowska, Hélène; Hoehener, Daniel
2017-06-01
This paper is devoted to pointwise second-order necessary optimality conditions for the Mayer problem arising in optimal control theory. We first show that with every optimal trajectory it is possible to associate a solution p (ṡ) of the adjoint system (as in the Pontryagin maximum principle) and a matrix solution W (ṡ) of an adjoint matrix differential equation that satisfy a second-order transversality condition and a second-order maximality condition. These conditions seem to be a natural second-order extension of the maximum principle. We then prove a Jacobson like necessary optimality condition for general control systems and measurable optimal controls that may be only ;partially singular; and may take values on the boundary of control constraints. Finally we investigate the second-order sensitivity relations along optimal trajectories involving both p (ṡ) and W (ṡ).
Second-order impartiality and public sphere
Directory of Open Access Journals (Sweden)
Sládeček Michal
2016-01-01
Full Text Available In the first part of the text the distinction between first- and second-order impartiality, along with Brian Barry’s thorough elaboration of their characteristics and the differences between them, is examined. While the former impartiality is related to non-favoring fellow-persons in everyday occasions, the latter is manifested in the institutional structure of society and its political and public morality. In the second part of the article, the concept of public impartiality is introduced through analysis of two examples. In the first example, a Caledonian Club with its exclusive membership is considered as a form of association which is partial, but nevertheless morally acceptable. In the second example, the so-called Heinz dilemma has been reconsidered and the author points to some flaws in Barry’s interpretation, arguing that Heinz’s right of giving advantage to his wife’s life over property rights can be recognized through mitigating circum-stances, and this partiality can be appreciated in the public sphere. Thus, public impartiality imposes limits to the restrictiveness and rigidity of political impartiality implied in second-order morality. [Projekat Ministarstva nauke Republike Srbije, br. 179049
Oscillation theory for second order dynamic equations
Agarwal, Ravi P; O''Regan, Donal
2003-01-01
The qualitative theory of dynamic equations is a rapidly developing area of research. In the last 50 years, the Oscillation Theory of ordinary, functional, neutral, partial and impulsive differential equations, and their discrete versions, has inspired many scholars. Hundreds of research papers have been published in every major mathematical journal. Many books deal exclusively with the oscillation of solutions of differential equations, but most of these books appeal only to researchers who already know the subject. In an effort to bring Oscillation Theory to a new and broader audience, the authors present a compact, but thorough, understanding of Oscillation Theory for second order differential equations. They include several examples throughout the text not only to illustrate the theory, but also to provide new direction.
Nonlinear elliptic equations of the second order
Han, Qing
2016-01-01
Nonlinear elliptic differential equations are a diverse subject with important applications to the physical and social sciences and engineering. They also arise naturally in geometry. In particular, much of the progress in the area in the twentieth century was driven by geometric applications, from the Bernstein problem to the existence of Kähler-Einstein metrics. This book, designed as a textbook, provides a detailed discussion of the Dirichlet problems for quasilinear and fully nonlinear elliptic differential equations of the second order with an emphasis on mean curvature equations and on Monge-Ampère equations. It gives a user-friendly introduction to the theory of nonlinear elliptic equations with special attention given to basic results and the most important techniques. Rather than presenting the topics in their full generality, the book aims at providing self-contained, clear, and "elementary" proofs for results in important special cases. This book will serve as a valuable resource for graduate stu...
Second order logic, set theory and foundations of mathematics
Väänänen, J.A.; Dybjer, P; Lindström, S; Palmgren, E; Sundholm, G
2012-01-01
The question, whether second order logic is a better foundation for mathematics than set theory, is addressed. The main difference between second order logic and set theory is that set theory builds up a transfinite cumulative hierarchy while second order logic stays within one application of the
Second-order singular pertubative theory for gravitational lenses
Alard, C.
2018-03-01
The extension of the singular perturbative approach to the second order is presented in this paper. The general expansion to the second order is derived. The second-order expansion is considered as a small correction to the first-order expansion. Using this approach, it is demonstrated that in practice the second-order expansion is reducible to a first order expansion via a re-definition of the first-order pertubative fields. Even if in usual applications the second-order correction is small the reducibility of the second-order expansion to the first-order expansion indicates a potential degeneracy issue. In general, this degeneracy is hard to break. A useful and simple second-order approximation is the thin source approximation, which offers a direct estimation of the correction. The practical application of the corrections derived in this paper is illustrated by using an elliptical NFW lens model. The second-order pertubative expansion provides a noticeable improvement, even for the simplest case of thin source approximation. To conclude, it is clear that for accurate modelization of gravitational lenses using the perturbative method the second-order perturbative expansion should be considered. In particular, an evaluation of the degeneracy due to the second-order term should be performed, for which the thin source approximation is particularly useful.
Second-Order Learning Methods for a Multilayer Perceptron
International Nuclear Information System (INIS)
Ivanov, V.V.; Purehvdorzh, B.; Puzynin, I.V.
1994-01-01
First- and second-order learning methods for feed-forward multilayer neural networks are studied. Newton-type and quasi-Newton algorithms are considered and compared with commonly used back-propagation algorithm. It is shown that, although second-order algorithms require enhanced computer facilities, they provide better convergence and simplicity in usage. 13 refs., 2 figs., 2 tabs
Generalised Recurrent Finsler Space of Second Order II | Uppal ...
African Journals Online (AJOL)
Sinha and Singh (1971 a, b, 1973) have studied recurrent Finsler spaces of second order and discussed the properties of recurrent curvature tensor and recurrence tensor fields in them. Singh (1981) has defined generalized recurrent Finsler space of second order and denoted it by G(2-Fn). This paper defines G-2 recurrent ...
Nontrivial Periodic Solutions for Nonlinear Second-Order Difference Equations
Directory of Open Access Journals (Sweden)
Tieshan He
2011-01-01
Full Text Available This paper is concerned with the existence of nontrivial periodic solutions and positive periodic solutions to a nonlinear second-order difference equation. Under some conditions concerning the first positive eigenvalue of the linear equation corresponding to the nonlinear second-order equation, we establish the existence results by using the topological degree and fixed point index theories.
Recursive belief manipulation and second-order false-beliefs
DEFF Research Database (Denmark)
Braüner, Torben; Blackburn, Patrick Rowan; Polyanskaya, Irina
2016-01-01
The literature on first-order false-belief is extensive, but less is known about the second-order case. The ability to handle second-order false-beliefs correctly seems to mark a cognitively significant step, but what is its status? Is it an example of *complexity only* development, or does it in...
Solution of IVP of Second Order ODE with Oscillatory Solutions ...
African Journals Online (AJOL)
Solution of IVP of Second Order ODE with Oscillatory Solutions using Variational Iterative Method (VIM) ... Abstract. A Numerical method for solution of IVP of second order with oscillatory solutions using VIM is developed. The method ... Keywords: Variational Iteration Method, Lagrange multiplier, oscillatory solutions, ODE.
Directory of Open Access Journals (Sweden)
Ram Verma
2016-02-01
Full Text Available This paper deals with mainly establishing numerous sets of generalized second order paramertic sufficient optimality conditions for a semiinfinite discrete minmax fractional programming problem, while the results on semiinfinite discrete minmax fractional programming problem achieved based on some partitioning schemes under various types of generalized second order univexity assumptions.
Canonical description of a second-order achromat
International Nuclear Information System (INIS)
Kheifets, S.A.; Fieguth, T.H.; Ruth, R.D.
1988-03-01
Charged particle motion in second-order magnetic optical achromat is described using a canonical perturbation theory. Necessary and sufficient conditions for the existence of such a device are presented. Given these conditions, the second-order matrix elements at the end of the achromat are found explicity. It is shown that all geometric matrix elements are equal to zero and all chromatic matrix elements are either also equal to zero or proportional to the corresponding chromaticity. Thus all second-order matrix elements vanish simultaneously when the two chromaticities are made to be equal to zero 13 refs., 1 tab
Method to render second order beam optics programs symplectic
International Nuclear Information System (INIS)
Douglas, D.; Servranckx, R.V.
1984-10-01
We present evidence that second order matrix-based beam optics programs violate the symplectic condition. A simple method to avoid this difficulty, based on a generating function approach to evaluating transfer maps, is described. A simple example illustrating the non-symplectricity of second order matrix methods, and the effectiveness of our solution to the problem, is provided. We conclude that it is in fact possible to bring second order matrix optics methods to a canonical form. The procedure for doing so has been implemented in the program DIMAT, and could be implemented in programs such as TRANSPORT and TURTLE, making them useful in multiturn applications. 15 refs
Reflection-Symmetric Second-Order Topological Insulators and Superconductors.
Langbehn, Josias; Peng, Yang; Trifunovic, Luka; von Oppen, Felix; Brouwer, Piet W
2017-12-15
Second-order topological insulators are crystalline insulators with a gapped bulk and gapped crystalline boundaries, but with topologically protected gapless states at the intersection of two boundaries. Without further spatial symmetries, five of the ten Altland-Zirnbauer symmetry classes allow for the existence of such second-order topological insulators in two and three dimensions. We show that reflection symmetry can be employed to systematically generate examples of second-order topological insulators and superconductors, although the topologically protected states at corners (in two dimensions) or at crystal edges (in three dimensions) continue to exist if reflection symmetry is broken. A three-dimensional second-order topological insulator with broken time-reversal symmetry shows a Hall conductance quantized in units of e^{2}/h.
Second-order nonlinear optical metamaterials: ABC-type nanolaminates
International Nuclear Information System (INIS)
Alloatti, L.; Kieninger, C.; Lauermann, M.; Köhnle, K.; Froelich, A.; Wegener, M.; Frenzel, T.; Freude, W.; Leuthold, J.; Koos, C.
2015-01-01
We demonstrate a concept for second-order nonlinear metamaterials that can be obtained from non-metallic centrosymmetric constituents with inherently low optical absorption. The concept is based on iterative atomic-layer deposition of three different materials, A = Al 2 O 3 , B = TiO 2 , and C = HfO 2 . The centrosymmetry of the resulting ABC stack is broken since the ABC and the inverted CBA sequences are not equivalent—a necessary condition for non-zero second-order nonlinearity. In our experiments, we find that the bulk second-order nonlinear susceptibility depends on the density of interfaces, leading to a nonlinear susceptibility of 0.26 pm/V at a wavelength of 800 nm. ABC-type nanolaminates can be deposited on virtually any substrate and offer a promising route towards engineering of second-order optical nonlinearities at both infrared and visible wavelengths
Pyflation: Second Order Perturbations During Inflation Beyond Slow-roll
Huston, Ian
2011-03-01
Pyflation calculates cosmological perturbations during an inflationary expansion of the universe. The modules in the pyflation Python package can be used to run simulations of different scalar field models of the early universe. The main classes are contained in the cosmomodels module and include simulations of background fields and first order and second order perturbations. The sourceterm package contains modules required for the computation of the term required for the evolution of second order perturbations. Alongside the Python package, the bin directory contains Python scripts which can run first and second order simulations. A helper script called pyflation-qsubstart.py sets up a full second order run (including background, first order and source calculations) to be used on queueing system which contains the qsub executable (e.g. a Rocks cluster).
Abnormal Waves Modelled as Second-order Conditional Waves
DEFF Research Database (Denmark)
Jensen, Jørgen Juncher
2005-01-01
The paper presents results for the expected second order short-crested wave conditional of a given wave crest at a specific point in time and space. The analysis is based on the second order Sharma and Dean shallow water wave theory. Numerical results showing the importance of the spectral density......, the water depth and the directional spreading on the conditional mean wave profile are presented. Application of conditional waves to model and explain abnormal waves, e.g. the well-known New Year Wave measured at the Draupner platform January 1st 1995, is discussed. Whereas the wave profile can be modelled...... quite well by the second order conditional wave including directional spreading and finite water depth the probability to encounter such a wave is still, however, extremely rare. The use of the second order conditional wave as initial condition to a fully non-linear three-dimensional analysis...
Towards a General Methodology for Second-Order Science
Directory of Open Access Journals (Sweden)
Karl H. Müller
2014-08-01
Full Text Available In recent years a new science frontier emerged under the umbrella term of second-order science which creates new and challenging problems through a characteristic re-entry-operation like in pattern of patterns, learning of learning, cybernetics of cybernetics or logic of logic, which works with and on building blocks or elements of traditional or first-order scientific research and which, due to this re-entry configuration, becomes inherently reflexive. In this article I will pursue the ambitious goal to develop a general methodology for second-order science which is needed for second-order analyses from their initial stages up to the final steps. This general methodology will be framed as a sequence of recombination operations which become the central task for a particular step in the design of second-order investigations.
Second Order Sliding Mode Controller Design for Pneumatic Artificial Muscle
Ammar Al-Jodah; Laith Khames
2018-01-01
In this paper, first and second order sliding mode controllers are designed for a single link robotic arm actuated by two Pneumatic Artificial Muscles (PAMs). A new mathematical model for the arm has been developed based on the model of large scale pneumatic muscle actuator model. Uncertainty in parameters has been presented and tested for the two controllers. The simulation results of the second-order sliding mode controller proves to have a low tracking error and chattering effect as compar...
Second-Order Analytical Uncertainty Analysis in Life Cycle Assessment.
von Pfingsten, Sarah; Broll, David Oliver; von der Assen, Niklas; Bardow, André
2017-11-21
Life cycle assessment (LCA) results are inevitably subject to uncertainties. Since the complete elimination of uncertainties is impossible, LCA results should be complemented by an uncertainty analysis. However, the approaches currently used for uncertainty analysis have some shortcomings: statistical uncertainty analysis via Monte Carlo simulations are inherently uncertain due to their statistical nature and can become computationally inefficient for large systems; analytical approaches use a linear approximation to the uncertainty by a first-order Taylor series expansion and thus, they are only precise for small input uncertainties. In this article, we refine the analytical uncertainty analysis by a more precise, second-order Taylor series expansion. The presented approach considers uncertainties from process data, allocation, and characterization factors. We illustrate the refined approach for hydrogen production from methane-cracking. The production system contains a recycling loop leading to nonlinearities. By varying the strength of the loop, we analyze the precision of the first- and second-order analytical uncertainty approaches by comparing analytical variances to variances from statistical Monte Carlo simulations. For the case without loops, the second-order approach is practically exact. In all cases, the second-order Taylor series approach is more precise than the first-order approach, in particular for large uncertainties and for production systems with nonlinearities, for example, from loops. For analytical uncertainty analysis, we recommend using the second-order approach since it is more precise and still computationally cheap.
On holographic entanglement entropy with second order excitations
He, Song; Sun, Jia-Rui; Zhang, Hai-Qing
2018-03-01
We study the low-energy corrections to the holographic entanglement entropy (HEE) in the boundary CFT by perturbing the bulk geometry up to second order excitations. Focusing on the case that the boundary subsystem is a strip, we show that the area of the bulk minimal surface can be expanded in terms of the conserved charges, such as mass, angular momentum and electric charge of the AdS black brane. We also calculate the variation of the energy in the subsystem and verify the validity of the first law-like relation of thermodynamics at second order. Moreover, the HEE is naturally bounded at second order perturbations if the cosmic censorship conjecture for the dual black hole still holds.
Decomposition of a symmetric second-order tensor
Heras, José A.
2018-05-01
In the three-dimensional space there are different definitions for the dot and cross products of a vector with a second-order tensor. In this paper we show how these products can uniquely be defined for the case of symmetric tensors. We then decompose a symmetric second-order tensor into its ‘dot’ part, which involves the dot product, and the ‘cross’ part, which involves the cross product. For some physical applications, this decomposition can be interpreted as one in which the dot part identifies with the ‘parallel’ part of the tensor and the cross part identifies with the ‘perpendicular’ part. This decomposition of a symmetric second-order tensor may be suitable for undergraduate courses of vector calculus, mechanics and electrodynamics.
Second-Order Risk Constraints in Decision Analysis
Directory of Open Access Journals (Sweden)
Love Ekenberg
2014-01-01
Full Text Available Recently, representations and methods aimed at analysing decision problems where probabilities and values (utilities are associated with distributions over them (second-order representations have been suggested. In this paper we present an approach to how imprecise information can be modelled by means of second-order distributions and how a risk evaluation process can be elaborated by integrating procedures for numerically imprecise probabilities and utilities. We discuss some shortcomings of the use of the principle of maximising the expected utility and of utility theory in general, and offer remedies by the introduction of supplementary decision rules based on a concept of risk constraints taking advantage of second-order distributions.
An improved second-order continuum traffic model
Marques, W., Jr.; Velasco, R. M.
2010-02-01
We construct a second-order continuum traffic model by using an iterative procedure in order to derive a constitutive relation for the traffic pressure which is similar to the Navier-Stokes equation for ordinary fluids. Our second-order traffic model represents an improvement on the traffic model suggested by Kerner and Konhäuser since the iterative procedure introduces, in the constitutive relation for the traffic pressure, a density-dependent viscosity coefficient. By using a finite-difference scheme based on the Steger-Warming flux splitting, we investigate the solution of our improved second-order traffic model for specific problems like shock fronts in traffic and freeway-lane drop.
An improved second-order continuum traffic model
International Nuclear Information System (INIS)
Marques, W Jr; Velasco, R M
2010-01-01
We construct a second-order continuum traffic model by using an iterative procedure in order to derive a constitutive relation for the traffic pressure which is similar to the Navier–Stokes equation for ordinary fluids. Our second-order traffic model represents an improvement on the traffic model suggested by Kerner and Konhäuser since the iterative procedure introduces, in the constitutive relation for the traffic pressure, a density-dependent viscosity coefficient. By using a finite-difference scheme based on the Steger–Warming flux splitting, we investigate the solution of our improved second-order traffic model for specific problems like shock fronts in traffic and freeway-lane drop
Conformal conservation laws for second-order scalar fields
International Nuclear Information System (INIS)
Blakeskee, J.S.; Logan, J.D.
1976-01-01
It is considered an action integral over space-time whose Lagrangian depends upon a scalar field an upon derivatives of the field function up to second order. From invariance identities obtained by the authors in an earlier work it is shown how a new proof of Noether's theorem for this second-order problem follows in the multiple integral case. Finally, conservation laws are written down in the case that the given action integral be invariant under the fifteen-parameter special conformal group
Second order elastic metrics on the shape space of curves
DEFF Research Database (Denmark)
Bauer, Martin; Bruveris, Martins; Harms, Philipp
2015-01-01
Second order Sobolev metrics on the space of regular unparametrized planar curves have several desirable completeness properties not present in lower order metrics, but numerics are still largely missing. In this paper, we present algorithms to numerically solve the initial and boundary value...... problems for geodesics. The combination of these algorithms allows to compute Karcher means in a Riemannian gradient-based optimization scheme. Our framework has the advantage that the constants determining the weights of the zero, first, and second order terms of the metric can be chosen freely. Moreover...
More on Descriptive Complexity of Second-Order HORN Logics
Feng, Shiguang; Zhao, Xishun
2014-01-01
This paper concerns Gradel's question asked in 1992: whether all problems which are in PTIME and closed under substructures are definable in second-order HORN logic SO-HORN. We introduce revisions of SO-HORN and DATALOG by adding first-order universal quantifiers over the second-order atoms in the bodies of HORN clauses and DATALOG rules. We show that both logics are as expressive as FO(LFP), the least fixed point logic. We also prove that FO(LFP) can not define all of the problems that are i...
Second-order subsonic airfoil theory including edge effects
Van Dyke, Milton D
1956-01-01
Several recent advances in plane subsonic flow theory are combined into a unified second-order theory for airfoil sections of arbitrary shape. The solution is reached in three steps: the incompressible result is found by integration, it is converted into the corresponding subsonic compressible result by means of the second-order compressibility rule, and it is rendered uniformly valid near stagnation points by further rules. Solutions for a number of airfoils are given and are compared with the results of other theories and of experiment. A straight-forward computing scheme is outlined for calculating the surface velocities and pressures on any airfoil at any angle of attack
An integral for second-order multiple scattering perturbation theory
International Nuclear Information System (INIS)
Hoffman, G.G.
1997-01-01
This paper presents the closed form evaluation of a six-dimensional integral. The integral arises in the application to many-electron systems of a multiple scattering perturbation expansion at second order when formulated in fourier space. The resulting function can be used for the calculation of both the electron density and the effective one-electron potential in an SCF calculations. The closed form expression derived here greatly facilitates these calculations. In addition, the evaluated integral can be used for the computation of second-order corrections to the open-quotes optimized Thomas-Fermi theory.close quotes 10 refs., 2 figs
Second Order Sliding Mode Controller Design for Pneumatic Artificial Muscle
Directory of Open Access Journals (Sweden)
Ammar Al-Jodah
2018-01-01
Full Text Available In this paper, first and second order sliding mode controllers are designed for a single link robotic arm actuated by two Pneumatic Artificial Muscles (PAMs. A new mathematical model for the arm has been developed based on the model of large scale pneumatic muscle actuator model. Uncertainty in parameters has been presented and tested for the two controllers. The simulation results of the second-order sliding mode controller proves to have a low tracking error and chattering effect as compared to the first order one. The verification has been done by using MATLAB and Simulink software.
Improved system blind identification based on second-order ...
Indian Academy of Sciences (India)
An improved system blind identification method based on second-order cyclostationary statistics and the properties of group delay, has been proposed. This is achieved by applying a correction to the estimated phase (by the spectral correlation density of the system output) for the poles, in the group delay domain.
Accurate estimates of solutions of second order recursions
Mattheij, R.M.M.
1975-01-01
Two important types of two dimensional matrix-vector and second order scalar recursions are studied. Both types possess two kinds of solutions (to be called forward and backward dominant solutions). For the directions of these solutions sharp estimates are derived, from which the solutions
Second-order nonlinear optical metamaterials: ABC-type nanolaminates
Energy Technology Data Exchange (ETDEWEB)
Alloatti, L., E-mail: alloatti@mit.edu; Kieninger, C.; Lauermann, M.; Köhnle, K. [Institute of Photonics and Quantum Electronics (IPQ), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Froelich, A.; Wegener, M. [Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe (Germany); Frenzel, T. [Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Freude, W. [Institute of Photonics and Quantum Electronics (IPQ), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Institute for Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen (Germany); Leuthold, J.; Koos, C., E-mail: christian.koos@kit.edu [Institute of Photonics and Quantum Electronics (IPQ), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Institute for Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen (Germany)
2015-09-21
We demonstrate a concept for second-order nonlinear metamaterials that can be obtained from non-metallic centrosymmetric constituents with inherently low optical absorption. The concept is based on iterative atomic-layer deposition of three different materials, A = Al{sub 2}O{sub 3}, B = TiO{sub 2}, and C = HfO{sub 2}. The centrosymmetry of the resulting ABC stack is broken since the ABC and the inverted CBA sequences are not equivalent—a necessary condition for non-zero second-order nonlinearity. In our experiments, we find that the bulk second-order nonlinear susceptibility depends on the density of interfaces, leading to a nonlinear susceptibility of 0.26 pm/V at a wavelength of 800 nm. ABC-type nanolaminates can be deposited on virtually any substrate and offer a promising route towards engineering of second-order optical nonlinearities at both infrared and visible wavelengths.
Validity of second order analysis of superdense matter
International Nuclear Information System (INIS)
Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.
1975-01-01
The limitations of relativistic calculations of the properties of superdense matter obtained from strictly second order terms is discussed. Extension of the model to overcome these limitations leads to serious complications which can only be overcome by a fully self-consistent treatment. (U.S.)
Second order interference of chaotic light reflected from random medium
Zyuzin, A. Yu.
2014-01-01
We consider the reflection from a random medium of light with short coherence length. We found that the second order correlation function of light can have a peak in a direction where the reflection angle is equal to angle of incidence. This occurs when the size of the region, from which light is collected, is larger than the coherence length.
Improved family of block methods for special second order initial ...
African Journals Online (AJOL)
I.V.Ps]. ... Journal of the Nigerian Association of Mathematical Physics ... In this paper, efforts are directed towards generating a 2-block 3-point numerical method for solving the special second order initial value problems of the form Y\\" = F(X,Y) ...
Linear multistep method for solution of second order initial value ...
African Journals Online (AJOL)
Linear multistep method for solution of second order initial value problems of ordinary differential equations: a truncation error approach. M O Udo, G A Olayi, R A Ademiluyi. Abstract. No Abstract. Global Journal of Mathematical Sciences Vol. 6 (2) 2007: pp. 119-126. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL ...
Second order guiding-center Vlasov–Maxwell equations
DEFF Research Database (Denmark)
Madsen, Jens
2010-01-01
Second order gyrogauge invariant guiding-center coordinates with strong E×B-flow are derived using the Lie transformation method. The corresponding Poisson bracket structure and equations of motion are obtained. From a variational principle the explicit Vlasov–Maxwell equations are derived...
A probabilistic approach to second order variational inequalities with ...
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
. TX 78712, USA. ‡CMI, Université de Provence, 39, Rue F. J. Curie, 13 453 Marseille, France. Email: mkg@math.iisc.ernet.in; mrinal@ece.utexas.edu. MS received 5 April 2002; revised 8 May 2003. Abstract. We study a class of second order ...
PID control of second-order systems with hysteresis
Jayawardhana, Bayu; Logemann, Hartmut; Ryan, Eugene P.
2008-01-01
The efficacy of proportional, integral and derivative (PID) control for set point regulation and disturbance rejection is investigated in a context of second-order systems with hysteretic components. Two basic structures are studied: in the first, the hysteretic component resides (internally) in the
Implementing Second-Order Decision Analysis: Concepts, Algorithms, and Tool
Directory of Open Access Journals (Sweden)
Aron Larsson
2014-01-01
Full Text Available We present implemented concepts and algorithms for a simulation approach to decision evaluation with second-order belief distributions in a common framework for interval decision analysis. The rationale behind this work is that decision analysis with interval-valued probabilities and utilities may lead to overlapping expected utility intervals yielding difficulties in discriminating between alternatives. By allowing for second-order belief distributions over interval-valued utility and probability statements these difficulties may not only be remedied but will also allow for decision evaluation concepts and techniques providing additional insight into a decision problem. The approach is based upon sets of linear constraints together with generation of random probability distributions and utility values from implicitly stated uniform second-order belief distributions over the polytopes given from the constraints. The result is an interactive method for decision evaluation with second-order belief distributions, complementing earlier methods for decision evaluation with interval-valued probabilities and utilities. The method has been implemented for trial use in a user oriented decision analysis software.
Modeling Ability Differentiation in the Second-Order Factor Model
Molenaar, Dylan; Dolan, Conor V.; van der Maas, Han L. J.
2011-01-01
In this article we present factor models to test for ability differentiation. Ability differentiation predicts that the size of IQ subtest correlations decreases as a function of the general intelligence factor. In the Schmid-Leiman decomposition of the second-order factor model, we model differentiation by introducing heteroscedastic residuals,…
Equivalence problem of second order PDE for scale transformations
NODA, Takahiro
2011-01-01
The purpose of the paper is to consider an equivalence problem of second order partial differential equations for one unknown function of two independent variables under scale transformations. For this equivalence problem, explicit forms of invariant functions are given. In particular, if all of these invariant functions vanish, then PDEs are equivalent to the flat equation.
Second-Order Conditioning during a Compound Extinction Treatment
Pineno, Oskar; Zilski, Jessica M.; Schachtman, Todd R.
2007-01-01
Two conditioned taste aversion experiments with rats were conducted to establish if a target taste that had received a prior pairing with illness could be subject to second-order conditioning during extinction treatment in compound with a flavor that also received prior conditioning. In these experiments, the occurrence of second-order…
The confluent algorithm in second-order supersymmetric quantum mechanics
Salinas-Hernandez, E
2003-01-01
The confluent algorithm, a degenerate case of the second-order supersymmetric quantum mechanics, is studied. It is shown that the transformation function must asymptotically vanish to induce non-singular final potentials. The technique can be used to create a single level above the initial ground state energy. The method is applied to the free particle, one-soliton well and harmonic oscillator.
Second-Order Boundary Value Problem with Integral Boundary Conditions
Directory of Open Access Journals (Sweden)
Nieto JuanJ
2011-01-01
Full Text Available The nonlinear alternative of the Leray Schauder type and the Banach contraction principle are used to investigate the existence of solutions for second-order differential equations with integral boundary conditions. The compactness of solutions set is also investigated.
On second-order subdifferentials and their applications
Czech Academy of Sciences Publication Activity Database
Mordukhovich, B. S.; Outrata, Jiří
2001-01-01
Roč. 12, č. 1 (2001), s. 139-169 ISSN 1052-6234 Institutional research plan: AV0Z1075907 Keywords : variational analysis * Lipschitzian stability in optimization * second-order subdifferentials Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.086, year: 2001
Nonlinear second order evolution inclusions with noncoercive viscosity term
Papageorgiou, Nikolaos S.; Rădulescu, Vicenţiu D.; Repovš, Dušan D.
2018-04-01
In this paper we deal with a second order nonlinear evolution inclusion, with a nonmonotone, noncoercive viscosity term. Using a parabolic regularization (approximation) of the problem and a priori bounds that permit passing to the limit, we prove that the problem has a solution.
Infrared spectroscopy of the different types of second order structural ...
African Journals Online (AJOL)
Infrared spectroscopy of the different types of second order structural phase transitions in molecular crystals. G Djeteli, K Tepe, K Napo, R Guerin. Abstract. No Abstract. Global Journal of Pure and Applied Sciences Vol. 13 (1) 2007: pp. 119-123. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT ...
Oscillation of second order neutral dynamic equations with distributed delay
Directory of Open Access Journals (Sweden)
Qiaoshun Yang
2016-06-01
Full Text Available In this paper, we establish new oscillation criteria for second order neutral dynamic equations with distributed delay by employing the generalized Riccati transformation. The obtained theorems essentially improve the oscillation results in the literature. And two examples are provided to illustrate to the versatility of our main results.
On decreasing solutions of second order nearly linear differential equations
Czech Academy of Sciences Publication Activity Database
Řehák, Pavel
-, 21 March (2014), s. 62 ISSN 1687-2770 Institutional support: RVO:67985840 Keywords : nonlinear second order differential equation * decreasing solution * regularly varying function Subject RIV: BA - General Mathematics Impact factor: 1.014, year: 2014 http://www.boundaryvalueproblems.com/content/2014/1/62
Periodic and subharmonic solutions for second order p-Laplacian ...
Indian Academy of Sciences (India)
of periodic and subharmonic solutions to second order p-Laplacian difference equa- tions are obtained by using the critical point theory. The proof is based on the Linking theorem in combination with variational technique. Keywords. Periodic and subharmonic solutions; p-Laplacian; difference equations; discrete variational ...
Nonlinear second-order multivalued boundary value problems
Indian Academy of Sciences (India)
In this paper we study nonlinear second-order differential inclusions involving the ordinary vector -Laplacian, a multivalued maximal monotone operator and nonlinear multivalued boundary conditions. Our framework is general and unifying and incorporates gradient systems, evolutionary variational inequalities and the ...
Generalized second-order Coulomb phase shift functions
International Nuclear Information System (INIS)
Rosendorff, S.
1982-01-01
Some specific properties and the evaluation of the generalized second-order Coulomb phase shift functions (two-dimensional integrals of four spherical cylinder functions) are discussed. The dependence on the three momenta k 1 ,k-bar,k 2 , corresponding to the final, intermediate, and initial states is illustrated
Discrete second order trajectory generator with nonlinear constraints
Morselli, R.; Zanasi, R.; Stramigioli, Stefano
2005-01-01
A discrete second order trajectory generator for motion control systems is presented. The considered generator is a nonlinear system which receives as input a raw reference signal and provides as output a smooth reference signal satisfying nonlinear constraints on the output derivatives as UM-(x) ≤
Deconvolution of the thermoluminescent emission curve. Second order kinetics
International Nuclear Information System (INIS)
Moreno y M, A.; Moreno B, A.
1999-01-01
In this work it is described the Randall and Wilkins second order kinetics in Microsoft Excel language, which allows its expression as the sum of Gaussian and the correction factors corresponding. These factors are obtained of the differences between the real thermoluminescent curve and the Gaussian proposed. The results obtained justify the Gaussian expression added to the correction factor. (Author)
Existence of positive solutions for systems of second order multi ...
Indian Academy of Sciences (India)
In this paper, we establish the existence of positive solutions for systems of second order multi-point boundary value problems on time scales by applying Guo– Krasnosel'skii fixed point theorem. Author Affiliations. K R Prasad1 N Sreedhar2 M A S Srinivas3. Department of Applied Mathematics, Andhra University, ...
Second-order connected attribute filters using max-trees
Ouzounis, Georgios K.; Wilkinson, Michael H.F.; Ronse, C; Najman, L; Decenciere, E
2005-01-01
The work presented in this paper introduces a novel method for second-order connected attribute filtering using Max-Trees. The proposed scheme is generated in a recursive manner from two images, the original and a modified copy by an either extensive or an anti-extensive operator. The tree structure
Linearization of systems of four second-order ordinary differential ...
Indian Academy of Sciences (India)
In this paper we provide invariant linearizability criteria for a class of systems of four second-order ordinary differential equations in terms of a set of 30 constraint equations on the coefﬁcients of all derivative terms. The linearization criteria are derived by the analytic continuation of the geometric approach of projection of ...
Second-order phase transitions of pure substances
Schaftenaar, H.P.C.
2009-01-01
In this report we are dealing with the thermodynamic theory of second-order phase transitions or continuous transitions of unary systems. The first classification of these phase transitions is due to Ehrenfest (1933), based on chemical potentials. First-order transitions are changes in which the
Second order optical nonlinearity in silicon by symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Cazzanelli, Massimo, E-mail: massimo.cazzanelli@unitn.it [Laboratorio IdEA, Dipartimento di Fisica, Università di Trento, via Sommarive, 14 Povo (Trento) (Italy); Schilling, Joerg, E-mail: joerg.schilling@physik.uni-halle.de [Centre for Innovation Competence SiLi-nano, Martin-Luther-University Halle-Wittenberg, Karl-Freiherr-von-Fritsch Str. 3, 06120 Halle (Germany)
2016-03-15
Although silicon does not possess a dipolar bulk second order nonlinear susceptibility due to its centro-symmetric crystal structure, in recent years several attempts were undertaken to create such a property in silicon. This review presents the different sources of a second order susceptibility (χ{sup (2)}) in silicon and the connected second order nonlinear effects which were investigated up to now. After an introduction, a theoretical overview discusses the second order nonlinearity in general and distinguishes between the dipolar contribution—which is usually dominating in non-centrosymmetric structures—and the quadrupolar contribution, which even exists in centro-symmetric materials. Afterwards, the classic work on second harmonic generation from silicon surfaces in reflection measurements is reviewed. Due to the abrupt symmetry breaking at surfaces and interfaces locally a dipolar second order susceptibility appears, resulting in, e.g., second harmonic generation. Since the bulk contribution is usually small, the study of this second harmonic signal allows a sensitive observation of the surface/interface conditions. The impact of covering films, strain, electric fields, and defect states at the interfaces was already investigated in this way. With the advent of silicon photonics and the search for ever faster electrooptic modulators, the interest turned to the creation of a dipolar bulk χ{sup (2)} in silicon. These efforts have been focussing on several experiments applying an inhomogeneous strain to the silicon lattice to break its centro-symmetry. Recent results suggesting the impact of electric fields which are exerted from fixed charges in adjacent covering layers are also included. After a subsequent summary on “competing” concepts using not Si but Si-related materials, the paper will end with some final conclusions, suggesting possible future research direction in this dynamically developing field.
Hidden Second-order Stationary Spatial Point Processes
DEFF Research Database (Denmark)
Hahn, Ute; Jensen, Eva B. Vedel
2016-01-01
In the existing statistical literature, the almost default choice for inference on inhomogeneous point processes is the most well-known model class for inhomogeneous point processes: reweighted second-order stationary processes. In particular, the K-function related to this type of inhomogeneity ....... Using the new theoretical framework, we reanalyse three inhomogeneous point patterns that have earlier been analysed in the statistical literature and show that the conclusions concerning an appropriate model class must be revised for some of the point patterns.......In the existing statistical literature, the almost default choice for inference on inhomogeneous point processes is the most well-known model class for inhomogeneous point processes: reweighted second-order stationary processes. In particular, the K-function related to this type of inhomogeneity...
First- and second-order charged particle optics
Energy Technology Data Exchange (ETDEWEB)
Brown, K.L.; Servranckx, R.V.
1984-07-01
Since the invention of the alternating gradient principle there has been a rapid evolution of the mathematics and physics techniques applicable to charged particle optics. In this publication we derive a differential equation and a matrix algebra formalism valid to second-order to present the basic principles governing the design of charged particle beam transport systems. A notation first introduced by John Streib is used to convey the essential principles dictating the design of such beam transport systems. For example the momentum dispersion, the momentum resolution, and all second-order aberrations are expressed as simple integrals of the first-order trajectories (matrix elements) and of the magnetic field parameters (multipole components) characterizing the system. 16 references, 30 figures.
Modulation masking produced by second-order modulators
DEFF Research Database (Denmark)
Füllgrabe, Christian; Moore, Brian C.J.; Demany, Laurent
2005-01-01
Recent studies suggest that an auditory nonlinearity converts second-order sinusoidal amplitude modulation (SAM) (i.e., modulation of SAM depth) into a first-order SAM component, which contributes to the perception of second-order SAM. However, conversion may also occur in other ways......-carrier modulation frequency, phase relationship between the probe and masker modulator, and probe modulation depth. In experiment 1, the carrier was a 5-kHz sinusoid presented either alone or within a notched-noise masker in order to restrict off-frequency listening. In experiment 2, the carrier was a white noise....... The data obtained in both carrier conditions are consistent with the existence of a modulation distortion component. However, the phase yielding poorest detection performance varied across experimental conditions between 0° and 180°, confirming that, in addition to nonlinear mechanisms, cochlear filtering...
Second-Order Assortative Mixing in Social Networks
DEFF Research Database (Denmark)
Zhou, Shi; Cox, Ingemar; Hansen, Lars Kai
2017-01-01
In a social network, the number of links of a node, or node degree, is often assumed as a proxy for the node’s importance or prominence within the network. It is known that social networks exhibit the (first-order) assortative mixing, i.e. if two nodes are connected, they tend to have similar node...... degrees, suggesting that people tend to mix with those of comparable prominence. In this paper, we report the second-order assortative mixing in social networks. If two nodes are connected, we measure the degree correlation between their most prominent neighbours, rather than between the two nodes...... themselves. We observe very strong second-order assortative mixing in social networks, often significantly stronger than the first-order assortative mixing. This suggests that if two people interact in a social network, then the importance of the most prominent person each knows is very likely to be the same...
Measuring of Second-order Stochastic Dominance Portfolio Efficiency
Czech Academy of Sciences Publication Activity Database
Kopa, Miloš
2010-01-01
Roč. 46, č. 3 (2010), s. 488-500 ISSN 0023-5954 R&D Projects: GA ČR GAP402/10/1610 Institutional research plan: CEZ:AV0Z10750506 Keywords : stochastic dominance * stability * SSD porfolio efficiency Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.461, year: 2010 http://library.utia.cas.cz/separaty/2010/E/kopa-measuring of second-order stochastic dominance portfolio efficiency.pdf
Measurement Error in Designed Experiments for Second Order Models
McMahan, Angela Renee
1997-01-01
Measurement error (ME) in the factor levels of designed experiments is often overlooked in the planning and analysis of experimental designs. A familiar model for this type of ME, called the Berkson error model, is discussed at length. Previous research has examined the effect of Berkson error on two-level factorial and fractional factorial designs. This dissertation extends the examination to designs for second order models. The results are used to suggest ...
Periodic and boundary value problems for second order differential ...
Indian Academy of Sciences (India)
of multiple solutions for initial and boundary value problems of the first and second order. ... value problems. The overwhelming majority of the works in this direction, assume that the vector field is continuous in all variables and they look for solutions in the space. C2ً0; bق. ..... So from Vrabie [21] (Proposition 2.2.1, p. 56), we ...
Gravitational waves from global second order phase transitions
Energy Technology Data Exchange (ETDEWEB)
Jr, John T. Giblin [Department of Physics, Kenyon College, 201 North College Rd, Gambier, OH 43022 (United States); Price, Larry R.; Siemens, Xavier; Vlcek, Brian, E-mail: giblinj@kenyon.edu, E-mail: larryp@caltech.edu, E-mail: siemens@gravity.phys.uwm.edu, E-mail: bvlcek@uwm.edu [Center for Gravitation and Cosmology, Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)
2012-11-01
Global second-order phase transitions are expected to produce scale-invariant gravitational wave spectra. In this manuscript we explore the dynamics of a symmetry-breaking phase transition using lattice simulations. We explicitly calculate the stochastic gravitational wave background produced during the transition and subsequent self-ordering phase. We comment on this signal as it compares to the scale-invariant spectrum produced during inflation.
Discrete Weighted Pseudo Asymptotic Periodicity of Second Order Difference Equations
Directory of Open Access Journals (Sweden)
Zhinan Xia
2014-01-01
Full Text Available We define the concept of discrete weighted pseudo-S-asymptotically periodic function and prove some basic results including composition theorem. We investigate the existence, and uniqueness of discrete weighted pseudo-S-asymptotically periodic solution to nonautonomous semilinear difference equations. Furthermore, an application to scalar second order difference equations is given. The working tools are based on the exponential dichotomy theory and fixed point theorem.
Second-order reconstruction of the inflationary potential
International Nuclear Information System (INIS)
Liddle, A.R.; Turner, M.S.
1994-01-01
To first order in the deviation from scale invariance the inflationary potential and its first two derivatives can be expressed in terms of the spectral indices of the scalar and tensor perturbations, n and n T , and their contributions to the variance of the quadrupole CBR temperature anisotropy, S and T. In addition, there is a ''consistency relation'' between these quantities: n T =-1/7T/S. We discuss the overall strategy of perturbative reconstruction and derive the second-order expressions for the inflationary potential and its first two derivatives and the first-order expression for its third derivative, all in terms of n, n T , S, T, and dn/d lnk. We also obtain the second-order consistency relation, n T =-1/7(T/S)[1+0.11T/S+0.15(n-1)]. As an example we consider the exponential potential, the only known case where exact analytic solutions for the perturbation spectra exist. We reconstruct the potential via Taylor expansion (with coefficients calculated at both first and second order), and introduce the Pade approximant as a greatly improved alternative
Mixed hyperbolic-second-order-parabolic formulations of general relativity
International Nuclear Information System (INIS)
Paschalidis, Vasileios
2008-01-01
Two new formulations of general relativity are introduced. The first one is a parabolization of the Arnowitt-Deser-Misner formulation and is derived by the addition of combinations of the constraints and their derivatives to the right-hand side of the Arnowitt-Deser-Misner evolution equations. The desirable property of this modification is that it turns the surface of constraints into a local attractor because the constraint propagation equations become second-order parabolic independently of the gauge conditions employed. This system may be classified as mixed hyperbolic--second-order parabolic. The second formulation is a parabolization of the Kidder-Scheel-Teukolsky formulation and is a manifestly mixed strongly hyperbolic--second-order-parabolic set of equations, bearing thus resemblance to the compressible Navier-Stokes equations. As a first test, a stability analysis of flat space is carried out and it is shown that the first modification exponentially damps and smoothes all constraint-violating modes. These systems provide a new basis for constructing schemes for long-term and stable numerical integration of the Einstein field equations.
Second order hydrodynamics for a special class of gravity duals
Springer, T.
2009-04-01
The sound mode hydrodynamic dispersion relation is computed up to order q3 for a class of gravitational duals which includes both Schwarzschild AdS and Dp-brane metrics. The implications for second order transport coefficients are examined within the context of Israel-Stewart theory. These sound mode results are compared with previously known results for the shear mode. This comparison allows one to determine the third order hydrodynamic contributions to the shear mode for the class of metrics considered here.
Finite difference schemes for second order systems describing black holes
International Nuclear Information System (INIS)
Motamed, Mohammad; Kreiss, H-O.; Babiuc, M.; Winicour, J.; Szilagyi, B.
2006-01-01
In the harmonic description of general relativity, the principal part of Einstein's equations reduces to 10 curved space wave equations for the components of the space-time metric. We present theorems regarding the stability of several evolution-boundary algorithms for such equations when treated in second order differential form. The theorems apply to a model black hole space-time consisting of a spacelike inner boundary excising the singularity, a timelike outer boundary and a horizon in between. These algorithms are implemented as stable, convergent numerical codes and their performance is compared in a 2-dimensional excision problem
Optical implementation of a second-order neural network.
Zhang, L; Robinson, M G; Johnson, K M
1991-01-01
An optical implementation of a single-layer, second-order neural network is presented. The quadratic products are obtained by passing the optical beam twice through the input ferroelectric liquid-crystal (FLC) spatial light modulator (SLM), with the interconnection weights being implemented by a further two-dimensional 128 x 128 FLC SLM. The machine successfully associates eight randomly chosen pattern-target pairs (dimensions 16 and 4, respectively) and can learn the parity association. Translation invariance is also demonstrated. Results from a computer model indicate that input SLM contrast ratios of 4:1 and electronic noise of 10% of the maximum output can be tolerated.
Periodic boundary value problems of second order random differential equations
Directory of Open Access Journals (Sweden)
Bapurao Dhage
2009-04-01
Full Text Available In this paper, an existence and the existence of extremal random solutions are proved for a periodic boundary value problem of second order ordinary random differential equations. Our investigations have been placed in the space of real-valued functions defined and continuous on closed and bounded intervals of real line together with the applications of the random version of a nonlinear alternative of Leray-Schauder type and an algebraic random fixed point theorem of Dhage. An example is also indicated for demonstrating the realizations of the abstract theory developed in this paper.
Adaptive suboptimal second-order sliding mode control for microgrids
Incremona, Gian Paolo; Cucuzzella, Michele; Ferrara, Antonella
2016-09-01
This paper deals with the design of adaptive suboptimal second-order sliding mode (ASSOSM) control laws for grid-connected microgrids. Due to the presence of the inverter, of unpredicted load changes, of switching among different renewable energy sources, and of electrical parameters variations, the microgrid model is usually affected by uncertain terms which are bounded, but with unknown upper bounds. To theoretically frame the control problem, the class of second-order systems in Brunovsky canonical form, characterised by the presence of matched uncertain terms with unknown bounds, is first considered. Four adaptive strategies are designed, analysed and compared to select the most effective ones to be applied to the microgrid case study. In the first two strategies, the control amplitude is continuously adjusted, so as to arrive at dominating the effect of the uncertainty on the controlled system. When a suitable control amplitude is attained, the origin of the state space of the auxiliary system becomes attractive. In the other two strategies, a suitable blend between two components, one mainly working during the reaching phase, the other being the predominant one in a vicinity of the sliding manifold, is generated, so as to reduce the control amplitude in steady state. The microgrid system in a grid-connected operation mode, controlled via the selected ASSOSM control strategies, exhibits appreciable stability properties, as proved theoretically and shown in simulation.
Stochastic systems with delay: Perturbation theory for second order statistics
Energy Technology Data Exchange (ETDEWEB)
Frank, T.D., E-mail: till.frank@uconn.edu
2016-03-24
Within the framework of delay Fokker–Planck equations, a perturbation theoretical method is developed to determine second-order statistical quantities such as autocorrelation functions for stochastic systems with delay. Two variants of the perturbation theoretical approach are presented. The first variant is based on a non-local Fokker–Planck operator. The second variant requires to solve a Fokker–Planck equation with source term. It is shown that the two variants yield consistent results. The perturbation theoretical approaches are applied to study negative autocorrelations that are induced by feedback delays and mediated by the strength of the fluctuating forces that act on the feedback systems. - Highlights: • A perturbation theory for stochastic delay systems is presented. • The perturbation theory yields second order statistical quantities. • The theory is developed within the framework of delay Fokker–Planck equations. • The effective Fokker–Planck operator is a non-local operator in space. • Negative autocorrelations can be induced by time-delayed feedback.
Stochastic evaluation of second-order Dyson self-energies
Willow, Soohaeng Yoo; Kim, Kwang S.; Hirata, So
2013-04-01
A stochastic method is proposed that evaluates the second-order perturbation corrections to the Dyson self-energies of a molecule (i.e., quasiparticle energies or correlated ionization potentials and electron affinities) directly and not as small differences between two large, noisy quantities. With the aid of a Laplace transform, the usual sum-of-integral expressions of the second-order self-energy in many-body Green's function theory are rewritten into a sum of just four 13-dimensional integrals, 12-dimensional parts of which are evaluated by Monte Carlo integration. Efficient importance sampling is achieved with the Metropolis algorithm and a 12-dimensional weight function that is analytically integrable, is positive everywhere, and cancels all the singularities in the integrands exactly and analytically. The quasiparticle energies of small molecules have been reproduced within a few mEh of the correct values with 108 Monte Carlo steps. Linear-to-quadratic scaling of the size dependence of computational cost is demonstrated even for these small molecules.
Projective geometry of systems of second-order differential equations
International Nuclear Information System (INIS)
Aminova, A V; Aminov, N A
2006-01-01
It is proved that every projective connection on an n-dimensional manifold M is locally defined by a system S of n-1 second-order ordinary differential equations resolved with respect to the second derivatives and with right-hand sides cubic in the first derivatives, and that every differential system S defines a projective connection on M. The notion of equivalent differential systems is introduced and necessary and sufficient conditions are found for a system S to be reducible by a change of variables to a system whose integral curves are straight lines. It is proved that the symmetry group of a differential system S is a group of projective transformations in n-dimensional space with the associated projective connection and has dimension ≤n 2 +2n. Necessary and sufficient conditions are found for a system to admit the maximal symmetry group; basis vector fields and structure equations of the maximal symmetry Lie algebra are produced. As an application a classification is given of the systems S of two second-order differential equations admitting three-dimensional soluble symmetry groups.
On the universal identity in second order hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Grozdanov, S. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom); Instituut-Lorentz for Theoretical Physics, Leiden University,Niels Bohrweg 2, Leiden 2333 CA (Netherlands); Starinets, A.O. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom)
2015-03-02
We compute the ’t Hooft coupling correction to the infinite coupling expression for the second order transport coefficient λ{sub 2} in N=4SU(N{sub c}) supersymmetric Yang-Mills theory at finite temperature in the limit of infinite N{sub c}, which originates from the R{sup 4} terms in the low energy effective action of the dual type IIB string theory. Using this result, we show that the identity involving the three second order transport coefficients, 2ητ{sub Π}−4λ{sub 1}−λ{sub 2}=0, previously shown by Haack and Yarom to hold universally in relativistic conformal field theories with string dual descriptions to leading order in supergravity approximation, holds also at next to leading order in this theory. We also compute corrections to transport coefficients in a (hypothetical) strongly interacting conformal fluid arising from the generic curvature squared terms in the corresponding dual gravity action (in particular, Gauss-Bonnet action), and show that the identity holds to linear order in the higher-derivative couplings. We discuss potential implications of these results for the near-equilibrium entropy production rate at strong coupling.
On the universal identity in second order hydrodynamics
Grozdanov, S.; Starinets, A. O.
2015-03-01
We compute the 't Hooft coupling correction to the infinite coupling expression for the second order transport coefficient λ 2 in SU( N c ) supersymmetric Yang-Mills theory at finite temperature in the limit of infinite N c , which originates from the R 4 terms in the low energy effective action of the dual type IIB string theory. Using this result, we show that the identity involving the three second order transport coefficients, 2 ητ Π - 4 λ 1 - λ 2 = 0, previously shown by Haack and Yarom to hold universally in relativistic conformal field theories with string dual descriptions to leading order in supergravity approximation, holds also at next to leading order in this theory. We also compute corrections to transport coefficients in a (hypothetical) strongly interacting conformal fluid arising from the generic curvature squared terms in the corresponding dual gravity action (in particular, Gauss-Bonnet action), and show that the identity holds to linear order in the higher-derivative couplings. We discuss potential implications of these results for the near-equilibrium entropy production rate at strong coupling.
SECOND-ORDER CYBERNETICS, SEMIOTICS AND THE ART
Directory of Open Access Journals (Sweden)
Niculae V. Mihaita
2011-04-01
Full Text Available We take into consideration the concept of second order cybernetics and Pierce‘s approach of semiotics fundamentals. I am also an observer, experimenter and mental interpreter of metasigns given to the audience by Eugene Ionesco‘s absurd theatre. The interpreting of signs meaning is determinate by the context. From Semiotics ‗point of view, the objects I‘m studying (The Love Poem Lucifer or Evening Star, the short play Foursome and the most known, The Chairs gives me a lot of information about differences or NOT between actors, positive and negative interactions and become knowledge when I see them as signs. Second order cybernetics brings to the semiotics the idea of closure of structural coupling, interpretation and language [Soren, Cybersemiotics, 2008]. Them, the objects chosen are, for EXPERIMENTER, the YOYO in figure 1, and signifies the OBJECT of recursion. Boje [Boje, David, 2005] redefines antenarrative communication more holistically as an enactive phenomenon, and makes connections between varieties of disciplines in order to find out how antenarratives help us understand communication in the world. Instead of the finite event of producing an artifact, betting is a process and an end in itself, through which the practitioners might gain self-awareness. By synthesizing enactive-thinking in virtual space and the practice of communicating we appeal for valuable insights into the creative mind, challenging scholars and practitioners alike. Drawing contributions as above ideograms are useful for practicing cyberneticians, statisticians, researchers and academics, Informational Statistics applications [Mihaita, 2010] explores the ways in which liberal arts writers seek to involve, create and engage with new and diverse audiences from beginners encountering and participating in the work unexpectedly, to professionals from other disciplines and members of particular communities. Taking into consideration the Second-order Cybernetics
"H"-shape second order NLO polymers: synthesis and characterization.
Li, Zhong'an; Hu, Pan; Yu, Gui; Zhang, Wei; Jiang, Zuoquan; Liu, Yunqi; Ye, Cheng; Qin, Jingui; Li, Zhen
2009-02-28
In this work, two "H"-shape and one "AB"-type second order nonlinear optical (NLO) polymers were prepared for the first time. The linkage positions of chromophores in the "H"-shape polymers were shoulder-to-shoulder, in which the chromophore moieties were part of the polymeric backbone. The subtle structure could be easily modified by the introduction of different isolation groups, to adjust the property of the resultant polymers. All the polymers exhibited good film-forming ability and thermal stability. The second harmonic generation (SHG) experiments demonstrated that the two "H"-shape polymers (P1 and P2) exhibited large SHG coefficients of d(33) values (up to 90 pm V(-1)), and P2 even demonstrated relatively good long-term temporal stability.
Feature Scaling via Second-Order Cone Programming
Directory of Open Access Journals (Sweden)
Zhizheng Liang
2016-01-01
Full Text Available Feature scaling has attracted considerable attention during the past several decades because of its important role in feature selection. In this paper, a novel algorithm for learning scaling factors of features is proposed. It first assigns a nonnegative scaling factor to each feature of data and then adopts a generalized performance measure to learn the optimal scaling factors. It is of interest to note that the proposed model can be transformed into a convex optimization problem: second-order cone programming (SOCP. Thus the scaling factors of features in our method are globally optimal in some sense. Several experiments on simulated data, UCI data sets, and the gene data set are conducted to demonstrate that the proposed method is more effective than previous methods.
Isochronous bifurcations in second-order delay differential equations
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Andrea Bel
2014-07-01
Full Text Available In this article we consider a special type of second-order delay differential equations. More precisely, we take an equation of a conservative mechanical system in one dimension with an added term that is a function of the difference between the value of the position at time $t$ minus the position at the delayed time $t-\\tau$. For this system, we show that, under certain conditions of non-degeneration and of convergence of the periodic solutions obtained by the Homotopy Analysis Method, bifurcation branches appearing in a neighbourhood of Hopf bifurcation due to the delay are isochronous; i.e., all the emerging cycles have the same frequency.
Second order chromaticity of the interaction regions in the collider
International Nuclear Information System (INIS)
Sen, T.; Syphers, M.J.
1993-01-01
The collider in the SSC has large second order chromaticity (ξ 2 ) with the interaction regions (IRs) contributing substantially to it. The authors calculate the general expression for ξ 2 in a storage ring and find that it is driven by the first order chromatic beta wave. Specializing to the interaction regions, they show that ξ 2 is a minimum when the phase advance (Δμ IP -IP) between adjacent interaction points is an odd multiple of π/2 and both IRs are identical. In this case the first order chromatic beta wave is confined within the IRs. Conversely, ξ 2 is large either if δμ IP -IP = (2n + 1)π/2 and the two IRs are very far from equality or if the two IRs are equal but Δμ IP -IP = nπ
Riccati-parameter solutions of nonlinear second-order ODEs
International Nuclear Information System (INIS)
Reyes, M A; Rosu, H C
2008-01-01
It has been proven by Rosu and Cornejo-Perez (Rosu and Cornejo-Perez 2005 Phys. Rev. E 71 046607, Cornejo-Perez and Rosu 2005 Prog. Theor. Phys. 114 533) that for some nonlinear second-order ODEs it is a very simple task to find one particular solution once the nonlinear equation is factorized with the use of two first-order differential operators. Here, it is shown that an interesting class of parametric solutions is easy to obtain if the proposed factorization has a particular form, which happily turns out to be the case in many problems of physical interest. The method that we exemplify with a few explicitly solved cases consists in using the general solution of the Riccati equation, which contributes with one parameter to this class of parametric solutions. For these nonlinear cases, the Riccati parameter serves as a 'growth' parameter from the trivial null solution up to the particular solution found through the factorization procedure
Understanding operational risk capital approximations: First and second orders
Directory of Open Access Journals (Sweden)
Gareth W. Peters
2013-07-01
Full Text Available We set the context for capital approximation within the framework of the Basel II / III regulatory capital accords. This is particularly topical as the Basel III accord is shortly due to take effect. In this regard, we provide a summary of the role of capital adequacy in the new accord, highlighting along the way the significant loss events that have been attributed to the Operational Risk class that was introduced in the Basel II and III accords. Then we provide a semi-tutorial discussion on the modelling aspects of capital estimation under a Loss Distributional Approach (LDA. Our emphasis is to focuss on the important loss processes with regard to those that contribute most to capital, the so called “high consequence, low frequency" loss processes. This leads us to provide a tutorial overview of heavy tailed loss process modelling in OpRisk under Basel III, with discussion on the implications of such tail assumptions for the severity model in an LDA structure. This provides practitioners with a clear understanding of the features that they may wish to consider when developing OpRisk severity models in practice. From this discussion on heavy tailed severity models, we then develop an understanding of the impact such models have on the right tail asymptotics of the compound loss process and we provide detailed presentation of what are known as first and second order tail approximations for the resulting heavy tailed loss process. From this we develop a tutorial on three key families of risk measures and their equivalent second order asymptotic approximations: Value-at-Risk (Basel III industry standard; Expected Shortfall (ES and the Spectral Risk Measure. These then form the capital approximations. We then provide a few example case studies to illustrate the accuracy of these asymptotic captial approximations, the rate of the convergence of the assymptotic result as a function of the LDA frequency and severity model parameters, the sensitivity
Second order sliding mode control for a quadrotor UAV.
Zheng, En-Hui; Xiong, Jing-Jing; Luo, Ji-Liang
2014-07-01
A method based on second order sliding mode control (2-SMC) is proposed to design controllers for a small quadrotor UAV. For the switching sliding manifold design, the selection of the coefficients of the switching sliding manifold is in general a sophisticated issue because the coefficients are nonlinear. In this work, in order to perform the position and attitude tracking control of the quadrotor perfectly, the dynamical model of the quadrotor is divided into two subsystems, i.e., a fully actuated subsystem and an underactuated subsystem. For the former, a sliding manifold is defined by combining the position and velocity tracking errors of one state variable, i.e., the sliding manifold has two coefficients. For the latter, a sliding manifold is constructed via a linear combination of position and velocity tracking errors of two state variables, i.e., the sliding manifold has four coefficients. In order to further obtain the nonlinear coefficients of the sliding manifold, Hurwitz stability analysis is used to the solving process. In addition, the flight controllers are derived by using Lyapunov theory, which guarantees that all system state trajectories reach and stay on the sliding surfaces. Extensive simulation results are given to illustrate the effectiveness of the proposed control method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
Second order gyrokinetic theory for particle-in-cell codes
Tronko, Natalia; Bottino, Alberto; Sonnendrücker, Eric
2016-08-01
The main idea of the gyrokinetic dynamical reduction consists in a systematical removal of the fast scale motion (the gyromotion) from the dynamics of the plasma, resulting in a considerable simplification and a significant gain of computational time. The gyrokinetic Maxwell-Vlasov equations are nowadays implemented in for modeling (both laboratory and astrophysical) strongly magnetized plasmas. Different versions of the reduced set of equations exist, depending on the construction of the gyrokinetic reduction procedure and the approximations performed in the derivation. The purpose of this article is to explicitly show the connection between the general second order gyrokinetic Maxwell-Vlasov system issued from the modern gyrokinetic theory and the model currently implemented in the global electromagnetic Particle-in-Cell code ORB5. Necessary information about the modern gyrokinetic formalism is given together with the consistent derivation of the gyrokinetic Maxwell-Vlasov equations from first principles. The variational formulation of the dynamics is used to obtain the corresponding energy conservation law, which in turn is used for the verification of energy conservation diagnostics currently implemented in ORB5. This work fits within the context of the code verification project VeriGyro currently run at IPP Max-Planck Institut in collaboration with others European institutions.
Modal cost analysis for linear matrix-second-order systems
Skelton, R. E.; Hughes, P. C.
1980-01-01
Reduced models and reduced controllers for systems governed by matrix-second-order differential equations are obtained by retaining those modes which make the largest contributions to quadratic control objectives. Such contributions, expressed in terms of modal data, used as mode truncation criteria, allow the statement of the specific control objectives to influence the early model reduction from very high order models which are available, for example, from finite element methods. The relative importance of damping, frequency, and eigenvector in the mode truncation decisions are made explicit for each of these control objectives: attitude control, vibration suppression and figure control. The paper also shows that using modal cost analysis (MCA) on the closed loop modes of the optimally controlled system allows the construction of reduced control policies which feedback only those closed loop modal coordinates which are most critical to the quadratic control performance criterion. In this way, the modes which should be controlled (and hence the modes which must be observable by choice of measurements), are deduced from truncations of the optimal controller.
Monadic Second Order Logic on Tree-like Structures
DEFF Research Database (Denmark)
Walukiewicz, Igor
2002-01-01
An operation M* which constructs from a given structure M a tree-like structure whose domain consists of the finite sequences of elements of M is considered. A notion of automata running on such tree-like structures is defined. It is shown that automata of this kind characterise expressive power ...... is equivalent to first-order logic extended with unary least fixpoint operator.......An operation M* which constructs from a given structure M a tree-like structure whose domain consists of the finite sequences of elements of M is considered. A notion of automata running on such tree-like structures is defined. It is shown that automata of this kind characterise expressive power...... of monadic second-order logic (MSOL) over tree-like structures. Using this characterisation it is proved that MSOL theory of a tree-like structure is effectively reducible to that of the original structure. As another application of the characterisation it is shown that MSOL on trees of arbitrary degree...
Fuzzy Random Walkers with Second Order Bounds: An Asymmetric Analysis
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Georgios Drakopoulos
2017-03-01
Full Text Available Edge-fuzzy graphs constitute an essential modeling paradigm across a broad spectrum of domains ranging from artificial intelligence to computational neuroscience and social network analysis. Under this model, fundamental graph properties such as edge length and graph diameter become stochastic and as such they are consequently expressed in probabilistic terms. Thus, algorithms for fuzzy graph analysis must rely on non-deterministic design principles. One such principle is Random Walker, which is based on a virtual entity and selects either edges or, like in this case, vertices of a fuzzy graph to visit. This allows the estimation of global graph properties through a long sequence of local decisions, making it a viable strategy candidate for graph processing software relying on native graph databases such as Neo4j. As a concrete example, Chebyshev Walktrap, a heuristic fuzzy community discovery algorithm relying on second order statistics and on the teleportation of the Random Walker, is proposed and its performance, expressed in terms of community coherence and number of vertex visits, is compared to the previously proposed algorithms of Markov Walktrap, Fuzzy Walktrap, and Fuzzy Newman–Girvan. In order to facilitate this comparison, a metric based on the asymmetric metrics of Tversky index and Kullback–Leibler divergence is used.
two-group discriminant problem
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Constantine Loucopoulos
1997-01-01
Full Text Available A mixed-integer programming model (MIP incorporating prior probabilities for the two-group discriminant problem is presented. Its classificatory performance is compared against that of Fisher's linear discrimininant function (LDF and Smith's quadradic discriminant function (QDF for simulated data from normal and nonnormal populations for different settings of the prior probabilities of group membership. The proposed model is shown to outperform both LDF and QDF for most settings of the prior probabilities when the data are generated from nonnormal populations but underperforms the parametric models for data generated from normal populations.
Roof planes detection via a second-order variational model
Benciolini, Battista; Ruggiero, Valeria; Vitti, Alfonso; Zanetti, Massimo
2018-04-01
The paper describes a unified automatic procedure for the detection of roof planes in gridded height data. The procedure exploits the Blake-Zisserman (BZ) model for segmentation in both 2D and 1D, and aims to detect, to model and to label roof planes. The BZ model relies on the minimization of a functional that depends on first- and second-order derivatives, free discontinuities and free gradient discontinuities. During the minimization, the relative strength of each competitor is controlled by a set of weight parameters. By finding the minimum of the approximated BZ functional, one obtains: (1) an approximation of the data that is smoothed solely within regions of homogeneous gradient, and (2) an explicit detection of the discontinuities and gradient discontinuities of the approximation. Firstly, input data is segmented using the 2D BZ. The maps of data and gradient discontinuities are used to isolate building candidates and planar patches (i.e. regions with homogeneous gradient) that correspond to roof planes. Connected regions that can not be considered as buildings are filtered according to both patch dimension and distribution of the directions of the normals to the boundary. The 1D BZ model is applied to the curvilinear coordinates of boundary points of building candidates in order to reduce the effect of data granularity when the normals are evaluated. In particular, corners are preserved and can be detected by means of gradient discontinuity. Lastly, a total least squares model is applied to estimate the parameters of the plane that best fits the points of each planar patch (orthogonal regression with planar model). Refinement of planar patches is performed by assigning those points that are close to the boundaries to the planar patch for which a given proximity measure assumes the smallest value. The proximity measure is defined to account for the variance of a fitting plane and a weighted distance of a point from the plane. The effectiveness of the
Directory of Open Access Journals (Sweden)
Xuewen Mu
2015-01-01
quadratic programming over second-order cones and a bounded set. At each iteration, we only need to compute the metric projection onto the second-order cones and the projection onto the bound set. The result of convergence is given. Numerical results demonstrate that our method is efficient for the convex quadratic second-order cone programming problems with bounded constraints.
Dembo, Richard; Wareham, Jennifer; Schmeidler, James; Winters, Ken C
2016-01-01
Based on problem-behavior theory (Jessor & Jessor, 1977), a second-order problem behavior model of delinquency, marijuana use, and risky sexual behavior over five waves was estimated among truant adolescents. The study also investigated the influence of the problem factor on future arrest charges and the effect of socio-demographics on problem behavior and future crime. Results confirm the existence of a second-order latent factor of problem behaviors. Problem behaviors predicted more future arrest charges. Age was related to problem behaviors and future arrest charges, and family income was related to problem behavior. Implications for future research and practice are discussed.
Ho, Charlotte Yuk-Fan; Ling, Bingo Wing-Kuen; Reiss, Joshua D.
2007-01-01
In this paper, we find that, by computing the difference between two consecutive state vectors of second-order double-loop sigma-delta modulators (SDMs) and plotting one component of the subtracted vectors against the other component, irregular chaotic patterns will become two vertical lines. By multiplying a matrix on the subtracted vectors, it can be further transformed to two fixed points. However, second-order interpolative bandpass SDMs still exhibit chaotic behaviors after applying the ...
Energy Technology Data Exchange (ETDEWEB)
Ho, Charlotte Yuk-Fan [Department of Electronic Engineering, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)]. E-mail: charlotte.ho@elec.qmul.ac.uk; Ling, Bingo Wing-Kuen [Department of Electronic Engineering, Division of Engineering, King' s College London, Strand, London WC2R 2LS (United Kingdom)]. E-mail: wing-kuen.ling@kcl.ac.uk; Reiss, Joshua D. [Department of Electronic Engineering, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)]. E-mail: josh.reiss@elec.qmul.ac.uk
2007-08-15
In this paper, we find that, by computing the difference between two consecutive state vectors of second-order double-loop sigma-delta modulators (SDMs) and plotting one component of the subtracted vectors against the other component, irregular chaotic patterns will become two vertical lines. By multiplying a matrix on the subtracted vectors, it can be further transformed to two fixed points. However, second-order interpolative bandpass SDMs still exhibit chaotic behaviors after applying the same transformations. Moreover, it is found that the Lyapunov exponent of state vectors of second-order double-loop SDMs is higher than that of second-order interpolative bandpass SDMs, whereas the Lyapunov exponent of transformed vectors becomes negative infinity for second-order double-loop SDMs and increases for second-order interpolative bandpass SDMs. Hence, by examining the occurrence of chaotic behaviors of the transformed vectors of these two SDMs, these two SDMs can be distinguished from their state vectors and their transformed vectors without solving the state equations and knowing the information of input signals.
Ho, Yuk-Fan; Ling, Wing-Kuen; Reiss, Joshua; Yu, Xinghuo
2011-01-01
It is well known that second order lowpass interpolative sigma delta modulators (SDMs) may suffer from instability and limit cycle problems when the magnitudes of the input signals are at large and at intermediate levels, respectively. In order to solve these problems, we propose to replace the second order lowpass interpolative SDMs to a specific class of second order bandpass interpolative SDMs with the natural frequencies of the loop filters very close to zero. The global stability propert...
Snodgrass, Michael; Kalaida, Natasha; Winer, E Samuel
2009-06-01
Access can either be first-order or second-order. First order access concerns whether contents achieve representation in phenomenal consciousness at all; second-order access concerns whether phenomenally conscious contents are selected for metacognitive, higher order processing by reflective consciousness. When the optional and flexible nature of second-order access is kept in mind, there remain strong reasons to believe that exclusion failure can indeed isolate phenomenally conscious stimuli that are not so accessed. Irvine's [Irvine, E. (2009). Signal detection theory, the exclusion failure paradigm and weak consciousness-Evidence for the access/phenomenal distinction? Consciousness and Cognition.] partial access argument fails because exclusion failure is indeed due to lack of second-order access, not insufficient phenomenally conscious information. Further, the enable account conforms with both qualitative differences and subjective report, and is simpler than the endow account. Finally, although first-order access may be a distinct and important process, second-order access arguably reflects the core meaning of access generally.
Ferreira-Valente, Alexandra; Costa, Patrício; Elorduy, Marta; Virumbrales, Montserrat; Costa, Manuel J; Palés, Jorge
2016-09-19
Empathy is a key aspect of the physician-patient interactions. The Jefferson Scale of Empathy (JSE) is one of the most used empathy measures of medical students. The development of cross-cultural empathy studies depends on valid and reliable translations of the JSE. This study sought to: (1) adapt and assess the psychometric properties in Spanish students of the Spanish JSE validated in Mexican students; (2) test a second order latent factor model. The Spanish JSE was adapted from the Spanish JSE-S, resulting in a final version of the measure. A non-probabilistic sample of 1104 medical students of two Spanish medical schools completed a socio-demographic and the Spanish JSE-S. Descriptive statistics, along with a confirmatory factor analysis, the average variance extracted (AVE), Cronbach's alphas and composite reliability (CR) coefficients were computed. An independent samples t-test was performed to access sex differences. The Spanish JSE-S demonstrated acceptable to good sensitivity (individual items - except for item 2 - and JSE-S total score: -2.72 factor analysis supported the three-factor solution and the second order latent factor model. The findings provide support for the sensitivity, construct validity and reliability of the adapted Spanish JSE-S with Spanish medical students. Data confirm the hypothesized second order latent factor model. This version may be useful in future research examining empathy in Spanish medical students, as well as in cross-cultural studies.
Combined First and Second Order Total Variation Inpainting using Split Bregman
Papafitsoros, Konstantinos
2013-07-12
In this article we discuss the implementation of the combined first and second order total variation inpainting that was introduced by Papafitsoros and Schdönlieb. We describe the algorithm we use (split Bregman) in detail, and we give some examples that indicate the difference between pure first and pure second order total variation inpainting.
DEFF Research Database (Denmark)
Xin, Zhen; Qin, Zian; Lu, Minghui
2016-01-01
the principle of the SOGI-QSG, based on which, an improved Second-Order SOGI-QSG (SO-SOGI-QSG) is then proposed by referring the relationship of the standard FOS and the second-order system. The proposed SO-SOGI-QSG inherits the simplicity of the SOGI-QSG, while it has much stronger attenuation ability for both...
Adaptive waveform interpretation with Gaussian filtering (AWIGF) and second order bounded mean oscillation operator Z square 2(u,t,r) are TDR analysis methods based on second order differentiation. AWIGF was originally designed for relatively long probe (greater than 150 mm) TDR waveforms, while Z s...
Effects of Second-Order Hydrodynamics on a Semisubmersible Floating Offshore Wind Turbine: Preprint
Energy Technology Data Exchange (ETDEWEB)
Bayati, I.; Jonkman, J.; Robertson, A.; Platt, A.
2014-07-01
The objective of this paper is to assess the second-order hydrodynamic effects on a semisubmersible floating offshore wind turbine. Second-order hydrodynamics induce loads and motions at the sum- and difference-frequencies of the incident waves. These effects have often been ignored in offshore wind analysis, under the assumption that they are significantly smaller than first-order effects. The sum- and difference-frequency loads can, however, excite eigenfrequencies of the system, leading to large oscillations that strain the mooring system or vibrations that cause fatigue damage to the structure. Observations of supposed second-order responses in wave-tank tests performed by the DeepCwind consortium at the MARIN offshore basin suggest that these effects might be more important than originally expected. These observations inspired interest in investigating how second-order excitation affects floating offshore wind turbines and whether second-order hydrodynamics should be included in offshore wind simulation tools like FAST in the future. In this work, the effects of second-order hydrodynamics on a floating semisubmersible offshore wind turbine are investigated. Because FAST is currently unable to account for second-order effects, a method to assess these effects was applied in which linearized properties of the floating wind system derived from FAST (including the 6x6 mass and stiffness matrices) are used by WAMIT to solve the first- and second-order hydrodynamics problems in the frequency domain. The method has been applied to the OC4-DeepCwind semisubmersible platform, supporting the NREL 5-MW baseline wind turbine. The loads and response of the system due to the second-order hydrodynamics are analysed and compared to first-order hydrodynamic loads and induced motions in the frequency domain. Further, the second-order loads and induced response data are compared to the loads and motions induced by aerodynamic loading as solved by FAST.
Second order bounce back boundary condition for the lattice Boltzmann fluid simulation
International Nuclear Information System (INIS)
Kim, In Chan
2000-01-01
A new bounce back boundary method of the second order in error is proposed for the lattice Boltzmann fluid simulation. This new method can be used for the arbitrarily irregular lattice geometry of a non-slip boundary. The traditional bounce back boundary condition for the lattice Boltzmann simulation is of the first order in error. Since the lattice Boltzmann method is the second order scheme by itself, a boundary technique of the second order has been desired to replace the first order bounce back method. This study shows that, contrary to the common belief that the bounce back boundary condition is unilaterally of the first order, the second order bounce back boundary condition can be realized. This study also shows that there exists a generalized bounce back technique that can be characterized by a single interpolation parameter. The second order bounce back method can be obtained by proper selection of this parameter in accordance with the detailed lattice geometry of the boundary. For an illustrative purpose, the transient Couette and the plane Poiseuille flows are solved by the lattice Boltzmann simulation with various boundary conditions. The results show that the generalized bounce back method yields the second order behavior in the error of the solution, provided that the interpolation parameter is properly selected. Coupled with its intuitive nature and the ease of implementation, the bounce back method can be as good as any second order boundary method
Second-order focusing parallel electron energy magnetic sector analyzer designs
International Nuclear Information System (INIS)
Khursheed, Anjam
2011-01-01
This paper presents parallel magnetic sector analyzer designs that are predicted to have second-order or better focusing properties. Simulation results indicate that by reducing the gap between excitation plates in a compact parallel energy magnetic sector box design, second-order focusing regions in the detected energy spectrum can be obtained. A method for combining a first-order focusing magnetic box sector unit with a larger magnet sector unit is also presented in which, the field strength varies relatively slowly. Simulations predict that using a combination of such magnetic sector units, focusing properties better than second order can be achieved for most of the detected energy range.
Zheng, Guo; Wang, Jue; Wang, Lin; Zhou, Muchun; Xin, Yu; Song, Minmin
2017-11-15
The general formulae for second-order moments of Schell-model beams with various correlation functions in atmospheric turbulence are derived and validated by the Bessel-Gaussian Schell-model beams and cosine-Gaussian-correlated Schell-model beams. Our finding shows that the second-order moments of partially coherent Schell-model beams are related to the second-order partial derivatives of source spectral degree of coherence at the origin. The formulae we provide are much more convenient to analyze and research propagation problems in turbulence.
Second order limit laws for occupation times of the fractional Brownian motion
Xu, Fangjun
2013-01-01
We prove second order limit laws for (additive) functionals of the $d$-dimensional fractional Brownian motion with Hurst index $H=\\frac{1}{d}$, using the method of moments, extending the Kallianpur-Robbins law.
Second-order analysis of structured inhomogeneous spatio-temporal point processes
DEFF Research Database (Denmark)
Møller, Jesper; Ghorbani, Mohammad
Statistical methodology for spatio-temporal point processes is in its infancy. We consider second-order analysis based on pair correlation functions and K-functions for first general inhomogeneous spatio-temporal point processes and second inhomogeneous spatio-temporal Cox processes. Assuming...... spatio-temporal separability of the intensity function, we clarify different meanings of second-order spatio-temporal separability. One is second-order spatio-temporal independence and relates e.g. to log-Gaussian Cox processes with an additive covariance structure of the underlying spatio......-temporal Gaussian process. Another concerns shot-noise Cox processes with a separable spatio-temporal covariance density. We propose diagnostic procedures for checking hypotheses of second-order spatio-temporal separability, which we apply on simulated and real data (the UK 2001 epidemic foot and mouth disease data)....
Aspects of second-order analysis of structured inhomogeneous spatio-temporal processes
DEFF Research Database (Denmark)
Møller, Jesper; Ghorbani, Mohammad
2012-01-01
Statistical methodology for spatio-temporal point processes is in its infancy. We consider second-order analysis based on pair correlation functions and K-functions for general inhomogeneous spatio-temporal point processes and for inhomogeneous spatio-temporal Cox processes. Assuming spatio......-temporal separability of the intensity function, we clarify different meanings of second-order spatio-temporal separability. One is second-order spatio-temporal independence and relates to log-Gaussian Cox processes with an additive covariance structure of the underlying spatio-temporal Gaussian process. Another...... concerns shot-noise Cox processes with a separable spatio-temporal covariance density. We propose diagnostic procedures for checking hypotheses of second-order spatio-temporal separability, which we apply on simulated and real data....
Existence of infinitely many periodic solutions for second-order nonautonomous Hamiltonian systems
Directory of Open Access Journals (Sweden)
Wen Guan
2015-04-01
Full Text Available By using minimax methods and critical point theory, we obtain infinitely many periodic solutions for a second-order nonautonomous Hamiltonian systems, when the gradient of potential energy does not exceed linear growth.
Comparison of Second-Order Loads on a Tension-Leg Platform for Wind Turbines: Preprint
Energy Technology Data Exchange (ETDEWEB)
Gueydon, S.; Wuillaume, P.; Jonkman, J.; Robertson, A.; Platt, A.
2015-03-01
The first objective of this work is to compare the two floating offshore wind turbine simulation packages {DIFFRAC+aNySIM} and {WAMIT+FAST}. The focus is on second-order wave loads, and so first- and second-order wave loads are applied to a structure sequentially for a detailed comparison and a more precise analysis of the effects of the second-order loads. aNySIM does not have the capability to model flexible bodies, and so the simulations performed in this tool are done assuming a rigid body. FAST also assumes that the platform is rigid, but can account for the flexibility of the tower. The second objective is to study the effects of the second-order loads on the response of a TLP floating wind turbine. The flexibility of the tower must be considered for this investigation, and therefore only FAST is used.
Antiperiodic Boundary Value Problems for Second-Order Impulsive Ordinary Differential Equations
Directory of Open Access Journals (Sweden)
2009-02-01
Full Text Available We consider a second-order ordinary differential equation with antiperiodic boundary conditions and impulses. By using Schaefer's fixed-point theorem, some existence results are obtained.
Estimates on the minimal period for periodic solutions of nonlinear second order Hamiltonian systems
International Nuclear Information System (INIS)
Yiming Long.
1994-11-01
In this paper, we prove a sharper estimate on the minimal period for periodic solutions of autonomous second order Hamiltonian systems under precisely Rabinowitz' superquadratic condition. (author). 20 refs, 1 fig
Loads on a 3D body due to second order waves and a current
DEFF Research Database (Denmark)
Skourup, Jesper; Cheung, K. F.; Bingham, Harry B.
2000-01-01
Non-linear loads on a fixed body due to waves and a current are investigated. Potential theory is used to describe the flow, and a three-dimensional (3D) boundary element method (BEM), combined with a time-stepping procedure, is used to solve the problem. The exact free-surface boundary conditions...... are expanded about the still-water level by Taylor series so that the solution is evaluated on a time-invariant geometry. A formulation correct to second order in the wave steepness and to first order in the current speed is used. Numerical results are obtained for the first-order and the second......-order oscillatory forces and for the second-order mean force on a fixed vertical circular cylinder in waves and a current. The second-order oscillatory forces on the body in waves and current are new results, while the remaining force components are verified by comparison with established numerical and analytical...
Concordance measures and second order stochastic dominance-portfolio efficiency analysis
Czech Academy of Sciences Publication Activity Database
Kopa, Miloš; Tichý, T.
2012-01-01
Roč. 15, č. 4 (2012), s. 110-120 ISSN 1212-3609 R&D Projects: GA ČR(CZ) GBP402/12/G097 Institutional support: RVO:67985556 Keywords : dependency * concordance * portfolio selection * second order stochastic dominance Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.633, year: 2012 http://library.utia.cas.cz/separaty/2013/E/kopa-concordance measures and second order stochastic dominance- portfolio efficiency analysis.pdf
Esposito, Elena
2012-01-01
2010 - 2011 The aim of this research is the construction and the analysis of new families of numerical methods for the integration of special second order Ordinary Differential Equations (ODEs). The modeling of continuous time dynamical systems using second order ODEs is widely used in many elds of applications, as celestial mechanics, seismology, molecular dynamics, or in the semidiscretisation of partial differential equations (which leads to high dimensional systems and ...
Chadha, Alka; Bora, Swaroop Nandan
2017-11-01
This paper studies the existence, uniqueness, and exponential stability in mean square for the mild solution of neutral second order stochastic partial differential equations with infinite delay and Poisson jumps. By utilizing the Banach fixed point theorem, first the existence and uniqueness of the mild solution of neutral second order stochastic differential equations is established. Then, the mean square exponential stability for the mild solution of the stochastic system with Poisson jumps is obtained with the help of an established integral inequality.
First order and second order fermi acceleration of energetic charged particles by shock waves
International Nuclear Information System (INIS)
Webb, G.M.
1983-01-01
Steady state solutions of the cosmic ray transport equation describing first order Fermi acceleration of energetic charged particles at a plane shock (without losses) and second order Fermi acceleration in the downstream region of the shock are derived. The solutions for the isotropic part of the phase space distribution function are expressible as eigenfunction expansions, being superpositions of series of power law momentum spectra, with the power law indices being the roots of an eigenvalue equation. The above exact analytic solutions are for the case where the spatial diffusion coefficient kappa is independent of momentum. The solutions in general depend on the shock compression ratio, the modulation parameters V 1 L/kappa 1 , V 2 L/kappa 2 (V is the plasma velocity, kappa is the energetic particle diffusion coefficient, and L a characteristic length over which second order Fermi acceleration is effective) in the upstream and downstream regions of the shock, respectively, and also on a further dimensionless parameter, zeta, characterizing second order Fermi acceleration. In the limit as zeta→0 (no second order Fermi acceleration) the power law momentum spectrum characteristic of first order Fermi acceleration (depending only on the shock compression ratio) obtained previously is recovered. Perturbation solutions for the case where second order Fermi effects are small, and for realistic diffusion coefficients (kappainfinityp/sup a/, a>0, p = particle momentum), applicable at high momenta, are also obtained
Low Dimensional Vessiot-Guldberg-Lie Algebras of Second-Order Ordinary Differential Equations
Directory of Open Access Journals (Sweden)
Rutwig Campoamor-Stursberg
2016-03-01
Full Text Available A direct approach to non-linear second-order ordinary differential equations admitting a superposition principle is developed by means of Vessiot-Guldberg-Lie algebras of a dimension not exceeding three. This procedure allows us to describe generic types of second-order ordinary differential equations subjected to some constraints and admitting a given Lie algebra as Vessiot-Guldberg-Lie algebra. In particular, well-known types, such as the Milne-Pinney or Kummer-Schwarz equations, are recovered as special cases of this classification. The analogous problem for systems of second-order differential equations in the real plane is considered for a special case that enlarges the generalized Ermakov systems.
Constructing set-valued fundamental diagrams from jamiton solutions in second order traffic models
Seibold, Benjamin
2013-09-01
Fundamental diagrams of vehicular traiic ow are generally multivalued in the congested ow regime. We show that such set-valued fundamental diagrams can be constructed systematically from simple second order macroscopic traiic models, such as the classical Payne-Whitham model or the inhomogeneous Aw-Rascle-Zhang model. These second order models possess nonlinear traveling wave solutions, called jamitons, and the multi-valued parts in the fundamental diagram correspond precisely to jamiton-dominated solutions. This study shows that transitions from function-valued to set-valued parts in a fundamental diagram arise naturally in well-known second order models. As a particular consequence, these models intrinsically reproduce traiic phases. © American Institute of Mathematical Sciences.
ADPCM Using a Second-order Switched Predictor and Adaptive Quantizer
Directory of Open Access Journals (Sweden)
DESPOTOVIC, V.
2011-08-01
Full Text Available Adaptive differential pulse code modulation (ADPCM with forward gain-adaptive quantizer and second-order switched predictor based on correlation is presented in this article. Predictor consists of a bank of predetermined predictors for each block of speech samples, avoiding the need to solve, or quantize predictor coefficients during the coding process. The adaptation consists of switching to one of this predictors based on the values of the first and second order correlation coefficients. The theoretical model is generalization of the DPCM with the first order switched predictor for an arbitrary prediction order. Experimental results for ADPCM with the second-order four/eight state switched prediction based on correlation are provided.
Second-order all-fiber comb filter based on polarization-diversity loop configuration.
Lee, Yong Wook; Kim, Hyun-Tak; Lee, Yong Wan
2008-03-17
By concatenating three birefringence loops in series, a second-order all-fiber comb filter based on a polarization-diversity loop configuration is newly proposed. The proposed filter consists of one polarization beam splitter, polarization-maintaining fibers, and two halfwave plates. The effect of a second-order structure of polarization-maintaining fiber loops on a bandwidth of the filter passband was theoretically analyzed and experimentally demonstrated. Transmission output of the second-order filter (flat-top and narrow-band transmission spectra) could be obtained by adjusting two half-wave plates. 1 and 3 dB bandwidths of the proposed filter in flat-top and narrow-band operations were greater by approximately 102.9 and 44.3 % and smaller by approximately 47.9 and 47.1 % than those of a conventional Sagnac birefringence filter, respectively.
Time-dependent Second Order Scattering Theory for Weather Radar with a Finite Beam Width
Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood; Ito, Shigeo; Oguchi, Tomohiro
2006-01-01
Multiple scattering effects from spherical water particles of uniform diameter are studied for a W-band pulsed radar. The Gaussian transverse beam-profile and the rectangular pulse-duration are used for calculation. An second-order analytical solution is derived for a single layer structure, based on a time-dependent radiative transfer theory as described in the authors' companion paper. When the range resolution is fixed, increase in footprint radius leads to increase in the second order reflectivity that is defined as the ratio of the second order return to the first order one. This feature becomes more serious as the range increases. Since the spaceborne millimeter-wavelength radar has a large footprint radius that is competitive to the mean free path, the multiple scattering effect must be taken into account for analysis.
Stabilization and PID tuning algorithms for second-order unstable processes with time-delays.
Seer, Qiu Han; Nandong, Jobrun
2017-03-01
Open-loop unstable systems with time-delays are often encountered in process industry, which are often more difficult to control than stable processes. In this paper, the stabilization by PID controller of second-order unstable processes, which can be represented as second-order deadtime with an unstable pole (SODUP) and second-order deadtime with two unstable poles (SODTUP), is performed via the necessary and sufficient criteria of Routh-Hurwitz stability analysis. The stability analysis provides improved understanding on the existence of a stabilizing range of each PID parameter. Three simple PID tuning algorithms are proposed to provide desired closed-loop performance-robustness within the stable regions of controller parameters obtained via the stability analysis. The proposed PID controllers show improved performance over those derived via some existing methods. Copyright © 2017. Published by Elsevier Ltd.
First- and Second-Order Methodological Developments from the Coleman Report
Directory of Open Access Journals (Sweden)
Samuel R. Lucas
2016-09-01
Full Text Available Equality of Educational Opportunity was a watershed for sociological engagement with public policy, yet the questions the project addressed drew attention to several challenging methodological issues. Statistical advances, such as the multilevel model, were important first-order developments from the Coleman Report. Second-order developments, however, may be far less visible but perhaps even more important. Second-order developments of the Coleman Report stem from two sources: (1 social scientists’ reactions to proposed resolutions of the statistical challenges that the report navigated, and (2 Coleman’s own (perhaps implicit theoretical response to criticisms of such works as Equality of Educational Opportunity. Heightened interest in the challenge of identification serves as an example of the former type of second-order effect, whereas “Coleman’s boat” (Coleman 1990—and the social analytics that adopt, among other approaches, simulation strategies of inquiry consistent with Coleman’s typology of causal pathways—serves as an example of the latter. First-order developments take the questions as given and see the challenge as a practical, technical issue; second-order developments explicitly or implicitly reassess the question, treating the challenge as epistemological or social-theoretic. Second-order developments therefore may change the game, upsetting or rejecting routine practice at a fundamental level. I contend that as knowledge of second-order developments and their means of practical implementation in analyses diffuses among social analysts, they will prove of far more value than first-order developments to social understanding, sociology, and social policy.
Dynamical Consensus Algorithm for Second-Order Multi-Agent Systems Subjected to Communication Delay
International Nuclear Information System (INIS)
Liu Chenglin; Liu Fei
2013-01-01
To solve the dynamical consensus problem of second-order multi-agent systems with communication delay, delay-dependent compensations are added into the normal asynchronously-coupled consensus algorithm so as to make the agents achieve a dynamical consensus. Based on frequency-domain analysis, sufficient conditions are gained for second-order multi-agent systems with communication delay under leaderless and leader-following consensus algorithms respectively. Simulation illustrates the correctness of the results. (interdisciplinary physics and related areas of science and technology)
Pap-smear Classification Using Efficient Second Order Neural Network Training Algorithms
DEFF Research Database (Denmark)
Ampazis, Nikolaos; Dounias, George; Jantzen, Jan
2004-01-01
In this paper we make use of two highly efficient second order neural network training algorithms, namely the LMAM (Levenberg-Marquardt with Adaptive Momentum) and OLMAM (Optimized Levenberg-Marquardt with Adaptive Momentum), for the construction of an efficient pap-smear test classifier. The alg......In this paper we make use of two highly efficient second order neural network training algorithms, namely the LMAM (Levenberg-Marquardt with Adaptive Momentum) and OLMAM (Optimized Levenberg-Marquardt with Adaptive Momentum), for the construction of an efficient pap-smear test classifier...
Hybrid approximations via second order combined dynamic derivatives on time scales
Directory of Open Access Journals (Sweden)
Qin Sheng
2007-09-01
Full Text Available This article focuses on the approximation of conventional second order derivative via the combined (diamond-$\\alpha$ dynamic derivative on time scales with necessary smoothness conditions embedded. We will show the constraints under which the second order dynamic derivative provides a consistent approximation to the conventional second derivative; the cases where the dynamic derivative approximates the derivative only via a proper modification of the existing formula; and the situations in which the dynamic derivative can never approximate consistently even with the help of available structure correction methods. Constructive error analysis will be given via asymptotic expansions for practical hybrid modeling and computational applications.
Guermond, Jean-Luc
2014-01-01
© 2014 Society for Industrial and Applied Mathematics. This paper proposes an explicit, (at least) second-order, maximum principle satisfying, Lagrange finite element method for solving nonlinear scalar conservation equations. The technique is based on a new viscous bilinear form introduced in Guermond and Nazarov [Comput. Methods Appl. Mech. Engrg., 272 (2014), pp. 198-213], a high-order entropy viscosity method, and the Boris-Book-Zalesak flux correction technique. The algorithm works for arbitrary meshes in any space dimension and for all Lipschitz fluxes. The formal second-order accuracy of the method and its convergence properties are tested on a series of linear and nonlinear benchmark problems.
Separation and extension of cover inequalities for second-order conic knapsack constraints with GUBs
DEFF Research Database (Denmark)
Atamtürk, Alper; Muller, Laurent Flindt; Pisinger, David
We consider the second-order conic equivalent of the classic knapsack polytope where the variables are subject to generalized upper bound constraints. We describe and compare a number of separation and extension algorithms which make use of the extra structure implied by the generalized upper bound...... constraints in order to strengthen the second-order conic equivalent of the classic cover cuts. We show that determining whether a cover can be extended with a variable is NP-hard. Computational experiments are performed comparing the proposed separation and extension algorithms. These experiments show...
Energy Technology Data Exchange (ETDEWEB)
Mancas, Stefan C. [Department of Mathematics, Embry–Riddle Aeronautical University, Daytona Beach, FL 32114-3900 (United States); Rosu, Haret C., E-mail: hcr@ipicyt.edu.mx [IPICYT, Instituto Potosino de Investigacion Cientifica y Tecnologica, Apdo Postal 3-74 Tangamanga, 78231 San Luis Potosí, SLP (Mexico)
2013-09-02
We emphasize two connections, one well known and another less known, between the dissipative nonlinear second order differential equations and the Abel equations which in their first-kind form have only cubic and quadratic terms. Then, employing an old integrability criterion due to Chiellini, we introduce the corresponding integrable dissipative equations. For illustration, we present the cases of some integrable dissipative Fisher, nonlinear pendulum, and Burgers–Huxley type equations which are obtained in this way and can be of interest in applications. We also show how to obtain Abel solutions directly from the factorization of second order nonlinear equations.
A global numerical solution of the radial Schroedinger equation by second-order perturbation theory
International Nuclear Information System (INIS)
Adam, G.
1979-01-01
A global numerical method, which uses second-order perturbation theory, is described for the solution of the radial Schroedinger equation. The perturbative numerical (PN) solution is derived in two stages: first, the original potential is approximated by a piecewise continuous parabolic function, and second, the resulting Schroedinger equation is solved on each integration step by second-order perturbation theory, starting with a step function reference approximation for the parabolic potential. We get a manageable PN algorithm, which shows an order of accuracy equal to six in the solution of the original Schroedinger equation, and is very stable against round off errors. (author)
Second-order infinitesimal bendings of surfaces of revolution with flattening at the poles
International Nuclear Information System (INIS)
Sabitov, I Kh
2014-01-01
We study infinitesimal bendings of surfaces of revolution with flattening at the poles. We begin by considering the minimal possible smoothness class C 1 both for surfaces and for deformation fields. Conditions are formulated for a given harmonic of a first-order infinitesimal bending to be extendable into a second order infinitesimal bending. We finish by stating a criterion for nonrigidity of second order for closed surfaces of revolution in the analytic class. We also give the first concrete example of such a nonrigid surface. Bibliography: 15 entries
How to Convexify the Intersection of a Second Order Cone and a Nonconvex Quadratic
Burer, Sam; Kilinc-Karzan, Fatma
2014-01-01
A recent series of papers has examined the extension of disjunctive-programming techniques to mixed-integer second-order-cone programming. For example, it has been shown---by several authors using different techniques---that the convex hull of the intersection of an ellipsoid, $E$, and a split disjunction, $(l - x_j)(x_j - u) \\le 0$ with $l < u$, equals the intersection of $E$ with an additional second-order-cone representable (SOCr) set. In this paper, we study more general intersections of ...
DEFF Research Database (Denmark)
Tahavori, Maryamsadat; Shaker, Hamid Reza
gramians within the time interval to build the appropriate Petrov-Galerkin projection for dynamical systems within the time interval of interest. The bound on approximation error is also derived. The numerical results are compared with the counterparts from other techniques. The results confirm......A method for model reduction of dynamical systems with the second order structure is proposed in this paper. The proposed technique preserves the second order structure of the system, and also preserves the stability of the original systems. The method uses the controllability and observability...
A New Grünwald-Letnikov Derivative Derived from a Second-Order Scheme
Directory of Open Access Journals (Sweden)
B. A. Jacobs
2015-01-01
Full Text Available A novel derivation of a second-order accurate Grünwald-Letnikov-type approximation to the fractional derivative of a function is presented. This scheme is shown to be second-order accurate under certain modifications to account for poor accuracy in approximating the asymptotic behavior near the lower limit of differentiation. Some example functions are chosen and numerical results are presented to illustrate the efficacy of this new method over some other popular choices for discretizing fractional derivatives.
A Novel Second-Order All-Pass Filter Using Square-Root Domain Blocks
Surav Yilmaz, S.; Tola, A. T.; Arslanalp, R.
2013-01-01
In this study, a new second order all-pass filter is synthesized in the square-root domain by using the state-space method. The proposed second order all-pass filter is constituted by current mirrors, current sources, current-mode square-root circuits and capacitors. The pole frequency of the filter can be tuned electronically by varying the values of the current sources of this circuit. The filter is simulated in PSpice using 0.35um CMOS technology parameters. Quality factor of the circuit i...
Spectrum of Discrete Second-Order Difference Operator with Sign-Changing Weight and Its Applications
Directory of Open Access Journals (Sweden)
Ruyun Ma
2014-01-01
Full Text Available Let T>1 be an integer, and let=1,2,…,T. We discuss the spectrum of discrete linear second-order eigenvalue problems Δ2ut-1+λmtut=0, t∈, u0=uT+1=0, where λ≠0 is a parameter, m:→ℝ changes sign and mt≠0 on . At last, as an application of this spectrum result, we show the existence of sign-changing solutions of discrete nonlinear second-order problems by using bifurcate technique.
Anisotropy-induced transformation of a phase transition from first to second order
Energy Technology Data Exchange (ETDEWEB)
Nicolaides, Demetris [Natural Sciences and Mathematics, Bloomfield College, 467 Franklin Street, Bloomfield, NJ 07003 (United States)]. E-mail: demetris_nicolaides@bloomfield.edu
2005-09-19
Fluctuation-induced first order phase transitions are known to exist in rotation-invariant systems with coupled order parameters. Using exact calculations, it is shown that when a uniform uniaxial anisotropy is added, critical behavior corresponding to second order transitions is restored.
Euler-Lagrange hyperbolic systems of the second order and relativistic strings
International Nuclear Information System (INIS)
Ruggeri, T.
1978-01-01
It is proved that the only Lorentz covariant Lagrangian density for a general second order quasi-linear hyperbolic system in diagonal form is a stringlike one, which includes the Heisenberg-Euler scalar field Lagrangian. Complete exceptionality is also proved
Oscillation theory for a pair of second order dynamic equations with a singular interface
Directory of Open Access Journals (Sweden)
Pallav Kumar Baruah
2008-03-01
Full Text Available In this paper we consider a pair of second order dynamic equations defined on the time scale $I = [a,c]cup [sigma(c,b]$. We impose matching interface conditions at the singular interface $c$. We prove a theorem regarding the relationship between the number of eigenvalues and zeros of the corresponding eigenfunctions.
Representation of women in second-order elections: the Czech Republic and Slovakia compared
Czech Academy of Sciences Publication Activity Database
Kovář, J.; Kovář, Kamil
2014-01-01
Roč. 15, č. 1 (2014), s. 1-18 ISSN 1570-5854 R&D Projects: GA MŠk(CZ) SVV260126 Institutional support: PRVOUK-P23 Keywords : European Parliament * second-order elections * political parties * women's representation Subject RIV: AH - Economics
Independence of First- and Second-Order Memories in Newborn Rabbits
Coureaud, Gerard; Languille, Solene; Joly, Virginie; Schaal, Benoist; Hars, Bernard
2011-01-01
The mammary pheromone promotes the acquisition of novel odorants (CS1) in newborn rabbits. Here, experiments pinpoint that CS1 becomes able to support neonatal learning of other odorants (CS2). We therefore evaluated whether these first- and second-order memories remained dependent after reactivation. Amnesia induced after CS2 recall selectively…
A second-order autocorrelator for single-shot measurement of ...
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
background intensity contrast ratio of 25 ps laser pulses from an active-passive mode-locked. Nd:YLF laser carried out in this mode are also presented. 2. Principle. The second order autocorrelation technique basically involves splitting a laser beam into two beams of equal intensity and overlapping them in a nonlinear ...
Semantic Characterisations of Second-Order Computability over the Real Numbers
DEFF Research Database (Denmark)
Korovina, Margarita V.; Kudinov, Oleg V.
2001-01-01
We propose semantic characterisations of second-order computability over the reals based on σ-definability theory. Notions of computability for operators and real-valued functionals defined on the class of continuous functions are introduced via domain theory. We consider the reals with and without...
Second-Order Scaling in the Two-Flavor QCD Chiral Transition
Berera, Arjun
1994-01-01
Scaling behavior is analyzed for the two-flavor QCD lattice gauge theory chiral transition. Leading scaling behavior and correction to leading scaling from lattice spacing effects are examined for the quark condensate. Scaling predictions under the assumption of quark mass dominance are tested for the longitudinal correlation length. Second order scaling behavior is consistent with present data.
Second-order wave kinematics conditional on a given wave crest
DEFF Research Database (Denmark)
Jensen, Jørgen Juncher
1996-01-01
-Gaussian contributions. As an application, the mean wave elevation and the associated wave kinematics are determined for a Stokes second-order wave theory. The results are compared to the linear (Gaussian) predictions and the effect of the non-linearities is quantified both for the wave profile and the horizontal wave...
Second Order Washout filter based Power Sharing Strategy for Uninterruptible Power Supply
DEFF Research Database (Denmark)
Lu, Jinghang; Savaghebi, Mehdi; Guerrero, Josep M.
2017-01-01
In this paper, first, the existing frequency and voltage amplitude restoration control strategies are reviewed. Moreover, the proposed second order washout filter control strategy is proposed to enhance the dynamic response under load disturbance. The physical parameter of the proposed method is ...
Algebraic properties of first integrals for systems of second-order ...
African Journals Online (AJOL)
Symmetries of the rst integrals for scalar linear or linearizable second- order ordinary differential equations (ODEs) have already been derived and shown to exhibit interesting properties. One of these is that the symmetry algebra sl(3; R ) is generated by the three triplets of symmetries of the functionally independent first ...
Energy Technology Data Exchange (ETDEWEB)
Deleuze, M.S.; Pickup, B.T.; Wilton, D.J.
2000-04-05
The authors present the theory of the electron propagator perturbed by an external electric field and show how it can be used to calculate a variety of one-electron linear response properties that are accurate through second order in electron correlation. Some illustrative calculations are discussed.
An Improved Second-Order Generalized Integrator Based Quadrature Signal Generator
DEFF Research Database (Denmark)
Xin, Zhen; Wang, Xiongfei; Qin, Zian
2016-01-01
The second-order generalized integrator based quadrature signal generator (SOGI-QSG) is able to produce in-quadrature signals for many applications, such as frequency estimation, grid synchronization, and harmonic extraction. However, the SOGI-QSG is sensitive to input dc and harmonic components...
Periodic solutions of singular second order differential equations : upper and lower functions
Czech Academy of Sciences Publication Activity Database
Hakl, Robert; Torres, P.J.; Zamora, M.
2011-01-01
Roč. 74, č. 18 (2011), s. 7078-7093 ISSN 0362-546X Institutional research plan: CEZ:AV0Z10190503 Keywords : second-order differential equation * singularity at the phase variable * Rayleigh-Plesset equation Subject RIV: BA - General Mathematics Impact factor: 1.536, year: 2011 http://www.sciencedirect.com/science/article/pii/S0362546X11005049
Asymptotic behavior and stability of second order neutral delay differential equations
Chen, G.L.; van Gaans, O.W.; Verduyn Lunel, Sjoerd
2014-01-01
We study the asymptotic behavior of a class of second order neutral delay differential equations by both a spectral projection method and an ordinary differential equation method approach. We discuss the relation of these two methods and illustrate some features using examples. Furthermore, a fixed
Multiple positive solutions for second order impulsive boundary value problems in Banach spaces
Directory of Open Access Journals (Sweden)
Zhi-Wei Lv
2010-06-01
Full Text Available By means of the fixed point index theory of strict set contraction operators, we establish new existence theorems on multiple positive solutions to a boundary value problem for second-order impulsive integro-differential equations with integral boundary conditions in a Banach space. Moreover, an application is given to illustrate the main result.
One-electron second-order optical activity of a helix
Maki, Jeffery J.; Persoons, André
1996-06-01
The second-order nonlinear-optical response of a chiral molecule is calculated. We model the optical response classically using a single electron bound to a helical path. The helical motion of the electron causes optical activity in the second-order response. The hyperpolarizability tensor of a single helix and the susceptibility tensor for a thin film of helices are given. We examine the process of second-harmonic generation from a chiral surface using the calculated susceptibility tensor. The efficiency of the harmonic generation is different for left- and right-hand circularly polarized fundamental light, which is ascribed to be a form of nonlinear optical activity. The roles of pitch and radius of the helix are readily seen in the microscopic and macroscopic second-order optical responses and in the surface second-harmonic generation, which may provide some insight for synthesizing new chiral compounds. Our results also allow us to draw conclusions about the relative strength and importance to second-order optical activity of electric- and magnetic-dipole transitions. For instance, we confirm that optical activity can occur in surface second-harmonic generation from electric-only response, but we find that magnetic response can make a similar contribution and thus should not be ignored.
Remark on periodic boundary-value problem for second-order linear ordinary differential equations
Czech Academy of Sciences Publication Activity Database
Dosoudilová, M.; Lomtatidze, Alexander
2018-01-01
Roč. 2018, č. 13 (2018), s. 1-7 ISSN 1072-6691 Institutional support: RVO:67985840 Keywords : second-order linear equation * periodic boundary value problem * unique solvability Subject RIV: BA - General Math ematics OBOR OECD: Applied math ematics Impact factor: 0.954, year: 2016 https://ejde. math .txstate.edu/Volumes/2018/13/abstr.html
On conjugacy of second-order half-linear differential equations on the real axis
Czech Academy of Sciences Publication Activity Database
Šremr, Jiří
2016-01-01
Roč. 2016, Č. 57 (2016), s. 1-28 ISSN 1417-3875 Institutional support: RVO:67985840 Keywords : second-order half-linear equation * conjugacy * oscillation Subject RIV: BA - General Math ematics Impact factor: 0.926, year: 2016 http://www. math .u-szeged.hu/ejqtde/periodica.html?periodica=1¶mtipus_ertek=publication¶m_ertek=4894
Existence of solutions for nonlinear mixed type integrodifferential equation of second order
Directory of Open Access Journals (Sweden)
Haribhau Laxman Tidke
2010-04-01
Full Text Available In this paper, we investigate the existence of solutions for nonlinear mixed Volterra-Fredholm integrodifferential equation of second order with nonlocal conditions in Banach spaces. Our analysis is based on Leray-Schauder alternative, rely on a priori bounds of solutions and the inequality established by B. G. Pachpatte.
Loads on a 3D body due to second order waves and a current
DEFF Research Database (Denmark)
Skourup, Jesper; Cheung, K. F.; Bingham, Harry B.
2000-01-01
are expanded about the still-water level by Taylor series so that the solution is evaluated on a time-invariant geometry. A formulation correct to second order in the wave steepness and to first order in the current speed is used. Numerical results are obtained for the first-order and the second...
Matheson, H E; Bilsbury, T G; McMullen, P A
2012-03-01
A large body of research suggests that faces are processed by a specialized mechanism within the human visual system. This specialized mechanism is made up of subprocesses (Maurer, LeGrand, & Mondloch, 2002). One subprocess, called second- order relational processing, analyzes the metric distances between face parts. Importantly, it is well established that other-race faces and contrast-reversed faces are associated with impaired performance on numerous face processing tasks. Here, we investigated the specificity of second-order relational processing by testing how this process is applied to faces of different race and photographic contrast. Participants completed a feature displacement discrimination task, directly measuring the sensitivity to second-order relations between face parts. Across three experiments we show that, despite absolute differences in sensitivity in some conditions, inversion impaired performance in all conditions. The presence of robust inversion effects for all faces suggests that second-order relational processing can be applied to faces of different race and photographic contrast.
Facao, M.; Lopes, A.; Silva, A. L.; Silva, P.
2011-01-01
We propose an undergraduate numerical project for simulating the results of the second-order correlation function as obtained by an intensity interference experiment for two kinds of light, namely bunched light with Gaussian or Lorentzian power density spectrum and antibunched light obtained from single-photon sources. While the algorithm for…
Boundary-value problems for first and second order functional differential inclusions
Directory of Open Access Journals (Sweden)
Shihuang Hong
2003-03-01
Full Text Available This paper presents sufficient conditions for the existence of solutions to boundary-value problems of first and second order multi-valued differential equations in Banach spaces. Our results obtained using fixed point theorems, and lead to new existence principles.
Non-linear second-order periodic systems with non-smooth potential
Indian Academy of Sciences (India)
In this paper we study second order non-linear periodic systems driven by the ordinary vector -Laplacian with a non-smooth, locally Lipschitz potential function. Our approach is variational and it is based on the non-smooth critical point theory. We prove existence and multiplicity results under general growth conditions on ...
Non-linear second-order periodic systems with non-smooth potential
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
Abstract. In this paper we study second order non-linear periodic systems driven by the ordinary vector p-Laplacian with a non-smooth, locally Lipschitz potential function. Our approach is variational and it is based on the non-smooth critical point theory. We prove existence and multiplicity results under general growth ...
On the Robustness of Hysteretic Second-Order Systems with PID : iISS approach
Ouyang, Ruiyue; Jayawardhana, Bayu; Andrieu, Vincent
2012-01-01
In this paper, we study the robustness property of a second-order linear plant controlled by a proportional, integral and derivative (PID) controller with a hysteretic actuator. The hysteretic actuator is modeled by a Duhem model that exhibits clockwise (CW) input-output (I/O) dynamics (such as the
Time-integration methods for finite element discretisations of the second-order Maxwell equation
Sarmany, D.; Bochev, Mikhail A.; van der Vegt, Jacobus J.W.
This article deals with time integration for the second-order Maxwell equations with possibly non-zero conductivity in the context of the discontinuous Galerkin finite element method (DG-FEM) and the H(curl)-conforming FEM. For the spatial discretisation, hierarchic H(curl)-conforming basis
Time-integration methods for finite element discretisations of the second-order Maxwell equation
Sarmany, D.; Bochev, Mikhail A.; van der Vegt, Jacobus J.W.
This article deals with time integration for the second-order Maxwell equations with possibly non-zero conductivity in the context of the discontinuous Galerkin finite element method DG-FEM) and the $H(\\mathrm{curl})$-conforming FEM. For the spatial discretisation, hierarchic
Solving Second-Order Ordinary Differential Equations without Using Complex Numbers
Kougias, Ioannis E.
2009-01-01
Ordinary differential equations (ODEs) is a subject with a wide range of applications and the need of introducing it to students often arises in the last year of high school, as well as in the early stages of tertiary education. The usual methods of solving second-order ODEs with constant coefficients, among others, rely upon the use of complex…
International Nuclear Information System (INIS)
Ivanyukovich, V.A.; Karas', V.I.; Lomako, V.M.
1989-01-01
A new radiation defect with a bistable configuration was discovered in gallium arsenide. It differed from similar known defects by an inversion of states caused by variation of temperature. It is shown that configuration-bistable modifications of the structure can be regarded as second-order phase transitions
Robust pole placement for second-order systems: an LMI approach
Czech Academy of Sciences Publication Activity Database
Henrion, D.; Šebek, Michael; Kučera, Vladimír
2005-01-01
Roč. 41, č. 1 (2005), s. 1-14 ISSN 0023-5954 R&D Projects: GA ČR GA102/02/0709 Institutional research plan: CEZ:AV0Z10750506 Keywords : polynomial matrix * second-order linear systems * LMI * pole placement * robust control Subject RIV: BC - Control Systems Theory Impact factor: 0.343, year: 2005
Directory of Open Access Journals (Sweden)
Tengfei Shen
2015-12-01
Full Text Available This paper deals with the multiplicity of solutions for Dirichlet boundary conditions of second-order quasilinear equations with impulsive effects. By using critical point theory, a new result is obtained. An example is given to illustrate the main result.
Remark on periodic boundary-value problem for second-order linear ordinary differential equations
Czech Academy of Sciences Publication Activity Database
Dosoudilová, M.; Lomtatidze, Alexander
2018-01-01
Roč. 2018, č. 13 (2018), s. 1-7 ISSN 1072-6691 Institutional support: RVO:67985840 Keywords : second-order linear equation * periodic boundary value problem * unique solvability Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 0.954, year: 2016 https://ejde.math.txstate.edu/Volumes/2018/13/abstr.html
Myshkis type oscillation criteria for second-order linear delay differential equations
Czech Academy of Sciences Publication Activity Database
Opluštil, Z.; Šremr, Jiří
2015-01-01
Roč. 178, č. 1 (2015), s. 143-161 ISSN 0026-9255 Institutional support: RVO:67985840 Keywords : linear second-order delay differential equation * oscillation criteria Subject RIV: BA - General Mathematics Impact factor: 0.664, year: 2015 http://link.springer.com/article/10.1007%2Fs00605-014-0719-y
Modeling of second order space charge driven coherent sum and difference instabilities
Directory of Open Access Journals (Sweden)
Yao-Shuo Yuan
2017-10-01
Full Text Available Second order coherent oscillation modes in intense particle beams play an important role for beam stability in linear or circular accelerators. In addition to the well-known second order even envelope modes and their instability, coupled even envelope modes and odd (skew modes have recently been shown in [Phys. Plasmas 23, 090705 (2016PHPAEN1070-664X10.1063/1.4963851] to lead to parametric instabilities in periodic focusing lattices with sufficiently different tunes. While this work was partly using the usual envelope equations, partly also particle-in-cell (PIC simulation, we revisit these modes here and show that the complete set of second order even and odd mode phenomena can be obtained in a unifying approach by using a single set of linearized rms moment equations based on “Chernin’s equations.” This has the advantage that accurate information on growth rates can be obtained and gathered in a “tune diagram.” In periodic focusing we retrieve the parametric sum instabilities of coupled even and of odd modes. The stop bands obtained from these equations are compared with results from PIC simulations for waterbag beams and found to show very good agreement. The “tilting instability” obtained in constant focusing confirms the equivalence of this method with the linearized Vlasov-Poisson system evaluated in second order.
Four New Applications of Second-Order Generalized Integrator Quadrature Signal Generator
DEFF Research Database (Denmark)
Xin, Zhen; Zhao, Rende; Wang, Xiongfei
2016-01-01
The Second-Order Generalized Integrator (SOGI) was used as a building block for the SOGI-Quadrature-Signal Generator (SOGI-QSG) which has been widely used for grid synchronization, frequency estimation, and harmonic extraction over the past decade. This paper further investigates its integration ...
On optimality of a second order rotatable design in three demensions
African Journals Online (AJOL)
In this paper, we use the existing second order rotatable design to for a basis for selecting optimum design based on the known classical optimality criteria. We estimate the particular values of the moments used for the existing design and determine the information matrix. The exact values of the particular cases in the family ...
Conformal symmetry and non-relativistic second-order fluid dynamics
International Nuclear Information System (INIS)
Chao Jingyi; Schäfer, Thomas
2012-01-01
We study the constraints imposed by conformal symmetry on the equations of fluid dynamics at second order in the gradients of the hydrodynamic variables. At zeroth order, conformal symmetry implies a constraint on the equation of state, E 0 =2/3 P, where E 0 is the energy density and P is the pressure. At first order, conformal symmetry implies that the bulk viscosity must vanish. We show that at second order, conformal invariance requires that two-derivative terms in the stress tensor must be traceless, and that it determines the relaxation of dissipative stresses to the Navier–Stokes form. We verify these results by solving the Boltzmann equation at second order in the gradient expansion. We find that only a subset of the terms allowed by conformal symmetry appear. - Highlights: ► We derive conformal constraints for the stress tensor of a scale invariant fluid. ► We determine the relaxation time in kinetic theory. ► We compute the rate of entropy production in second-order fluid dynamics.
Relative boundedness and compactness theory for second-order differential operators
Directory of Open Access Journals (Sweden)
Don B. Hinton
1997-01-01
Full Text Available The problem considered is to give necessary and sufficient conditions for perturbations of a second-order ordinary differential operator to be either relatively bounded or relatively compact. Such conditions are found for three classes of operators. The conditions are expressed in terms of integral averages of the coefficients of the perturbing operator.
Conservation of Autonomy: Toward a Second-Order Perspective on Psychosomatic Symptoms.
Fourie, David P.
1993-01-01
Considers families of people suffering from psychosomatic disorders from perspective of second-order cybernetics in which emphasis is on autonomy of various levels of system. Describes psychosomatic symptoms and illustrates symptoms as expression of ideas aimed at conservation of autonomy, both at individual and family level. Highlights…
DEFF Research Database (Denmark)
Chen, X.; Cui, W.; Jensen, Jørgen Juncher
2003-01-01
The theory and typical numerical results of a second order nonlinear hydroelastic analysis of floating bodies are presented in a series of papers in which only nonlinearity in fluids is considered. Under the assumption of linear fluid, the hydroelastic analysis methods of nonlinear structure are ...
Some oscillation criteria for the second-order linear delay differential equation
Czech Academy of Sciences Publication Activity Database
Opluštil, Z.; Šremr, Jiří
2011-01-01
Roč. 136, č. 2 (2011), s. 195-204 ISSN 0862-7959 Institutional research plan: CEZ:AV0Z10190503 Keywords : second-order linear differential equation with a delay * oscillatory solution Subject RIV: BA - General Mathematics http://www.dml.cz/handle/10338.dmlcz/141582
Ćaǧatay Uçgun, Filiz; Esen, Oǧul; Gümral, Hasan
2018-01-01
We present Skinner-Rusk and Hamiltonian formalisms of second order degenerate Clément and Sarıoğlu-Tekin Lagrangians. The Dirac-Bergmann constraint algorithm is employed to obtain Hamiltonian realizations of Lagrangian theories. The Gotay-Nester-Hinds algorithm is used to investigate Skinner-Rusk formalisms of these systems.
Super Twisting Second Order Sliding Mode Control for Position Tracking Control of Hydraulic Drives
DEFF Research Database (Denmark)
Schmidt, Lasse; Andersen, Torben Ole; Pedersen, Henrik C.
2013-01-01
In this paper a control strategy based on second order sliding modes, generally applicable for position tracking control of electro-hydraulic valve-cylinder drives (VCD), is proposed. The main target is to overcome problems with linear controllers deteriorating performance due to the strong...
International Nuclear Information System (INIS)
Hwang, Jai-chan; Noh, Hyerim
2007-01-01
We present general relativistic correction terms appearing in Newton's gravity to the second-order perturbations of cosmological fluids. In our previous work we have shown that to the second-order perturbations, the density and velocity perturbation equations of general relativistic zero-pressure, irrotational, single-component fluid in a spatially flat background coincide exactly with the ones known in Newton's theory without using the gravitational potential. We also have shown the effect of gravitational waves to the second order, and pure general relativistic correction terms appearing in the third-order perturbations. Here, we present results of second-order perturbations relaxing all the assumptions made in our previous works. We derive the general relativistic correction terms arising due to (i) pressure, (ii) multicomponent, (iii) background spatial curvature, and (iv) rotation. In the case of multicomponent zero-pressure, irrotational fluids under the flat background, we effectively do not have relativistic correction terms, thus the relativistic equations expressed in terms of density and velocity perturbations again coincide with the Newtonian ones. In the other three cases we generally have pure general relativistic correction terms. In the case of pressure, the relativistic corrections appear even in the level of background and linear perturbation equations. In the presence of background spatial curvature, or rotation, pure relativistic correction terms directly appear in the Newtonian equations of motion of density and velocity perturbations to the second order; to the linear order, without using the gravitational potential (or metric perturbations), we have relativistic/Newtonian correspondences for density and velocity perturbations of a single-component fluid including the rotation even in the presence of background spatial curvature. In the small-scale limit (far inside the horizon), to the second-order, relativistic equations of density and
Directly Solving Special Second Order Delay Differential Equations Using Runge-Kutta-Nyström Method
Directory of Open Access Journals (Sweden)
M. Mechee
2013-01-01
Full Text Available Runge-Kutta-Nyström (RKN method is adapted for solving the special second order delay differential equations (DDEs. The stability polynomial is obtained when this method is used for solving linear second order delay differential equation. A standard set of test problems is solved using the method together with a cubic interpolation for evaluating the delay terms. The same set of problems is reduced to a system of first order delay differential equations and then solved using the existing Runge-Kutta (RK method. Numerical results show that the RKN method is more efficient in terms of accuracy and computational time when compared to RK method. The methods are applied to a well-known problem involving delay differential equations, that is, the Mathieu problem. The numerical comparison shows that both methods are in a good agreement.
Emergence of Lévy Walks from Second-Order Stochastic Optimization
Kuśmierz, Łukasz; Toyoizumi, Taro
2017-12-01
In natural foraging, many organisms seem to perform two different types of motile search: directed search (taxis) and random search. The former is observed when the environment provides cues to guide motion towards a target. The latter involves no apparent memory or information processing and can be mathematically modeled by random walks. We show that both types of search can be generated by a common mechanism in which Lévy flights or Lévy walks emerge from a second-order gradient-based search with noisy observations. No explicit switching mechanism is required—instead, continuous transitions between the directed and random motions emerge depending on the Hessian matrix of the cost function. For a wide range of scenarios, the Lévy tail index is α =1 , consistent with previous observations in foraging organisms. These results suggest that adopting a second-order optimization method can be a useful strategy to combine efficient features of directed and random search.
Stability Analysis of a Class of Second Order Sliding Mode Control Including Delay in Input
Directory of Open Access Journals (Sweden)
Pedro R. Acosta
2013-01-01
Full Text Available This paper deals with a class of second order sliding mode systems. Based on the derivative of the sliding surface, sufficient conditions are given for stability. However, the discontinuous control signal depend neither on the derivative of sliding surface nor on its estimate. Time delay in control input is also an important issue in sliding mode control for engineering applications. Therefore, also sufficient conditions are given for the time delay size on the discontinuous input signal, so that this class of second order sliding mode systems might have amplitude bounded oscillations. Moreover, amplitude of such oscillations may be estimated. Some numerical examples are given to validate the results. At the end, some conclusions are given on the possibilities of the results as well as their limitations.
Second-order equation of motion for electromagnetic radiation back-reaction
Matolcsi, T.; Fülöp, T.; Weiner, M.
2017-09-01
We take the viewpoint that the physically acceptable solutions of the Lorentz-Dirac equation for radiation back-reaction are actually determined by a second-order equation of motion, the self-force being given as a function of spacetime location and velocity. We propose three different methods to obtain this self-force function. For two example systems, we determine the second-order equation of motion exactly in the non-relativistic regime via each of these three methods, leading to the same result. We reveal that, for both systems considered, back-reaction induces a damping proportional to velocity and, in addition, it decreases the effect of the external force.
A second-order approximation of particle motion in the fringing field of a dipole magnet
International Nuclear Information System (INIS)
Tarantin, N.I.
1980-01-01
The radial and axial motion of charged particles in the fringing field of an arbitrary dipole magnet has been considered with accuracy to the second-order of small quantities. The dipole magnet has an inhomogeneous field and oblique entrance and exit boundaries in the form of second-order curves. The region of the fringing field has a variable extension. A new definition of the effective boundary of the real fringing field has a variable extension. A new definition of the effective boundary of the real fringing field of the dipole magnet is used. A better understanding of the influence of the fringing magnetic field on the motion of charged particles in the pole gap of the dipole magnet has been obtained. In particular, it is shown that it is important to take into account, in the second approximation, some terms related formally to the next approximations. The results are presented in a form convenient for practical calculations. (orig.)
Full Stability of Locally Optimal Solutions in Second-Order Cone Programs
Czech Academy of Sciences Publication Activity Database
Mordukhovich, B. S.; Outrata, Jiří; Sarabi, E.
2014-01-01
Roč. 24, č. 4 (2014), s. 1581-1613 ISSN 1052-6234 R&D Projects: GA ČR GAP402/12/1309 Grant - others:Australian Research Council(AU) DP-12092508; Australian Research Council(AU) DP-110102011; Portuguese Foundation of Science and Technologies(PT) MAT/11109; USA National Science Foundation(US) DMS -1007132 Institutional support: RVO:67985556 Keywords : variational analysis * second-order cone programming * full stability of local minimizers * nondegeneracy * strong regularity * quadratic growth * second-order subdifferentials * coderivatives Subject RIV: BA - General Mathematics Impact factor: 1.829, year: 2014 http://library.utia.cas.cz/separaty/2014/MTR/outrata-0434303.pdf
Program Verification with Monadic Second-Order Logic & Languages for Web Service Development
DEFF Research Database (Denmark)
Møller, Anders
and verification techniques. This dissertation describes two projects, each exploring one particular instance of such languages: monadic second-order logic and its application to program verification, and programming languages for construction of interactive Web services. Both program verification and Web service...... applications, this implementation forms the basis of a verification technique for imperative programs that perform data-type operations using pointers. To achieve this, the basic logic is extended with layers of language abstractions. Also, a language for expressing data structures and operations along...... development are areas of programming language research that have received increased attention during the last years. We first show how the logic Weak monadic Second-order Logic on Strings and Trees can be implemented efficiently despite an intractable theoretical worst-case complexity. Among several other...
Beyond the G W approximation: A second-order screened exchange correction
Ren, Xinguo; Marom, Noa; Caruso, Fabio; Scheffler, Matthias; Rinke, Patrick
2015-08-01
Motivated by the recently developed renormalized second-order perturbation theory for ground-state energy calculations, we propose a second-order screened exchange correction (SOSEX) to the G W self-energy. This correction follows the spirit of the SOSEX correction to the random-phase approximation for the electron correlation energy and can be clearly represented in terms of Feynman diagrams. We benchmark the performance of the perturbative G0W0 +SOSEX scheme for a set of molecular systems, including the G2 test set from quantum chemistry as well as benzene and tetracyanoethylene. We find that G0W0 +SOSEX improves over G0W0 for the energy levels of the highest occupied and lowest unoccupied molecular orbitals. In addition, it can resolve some of the difficulties encountered by the G W method for relative energy positions as exemplified by benzene where the energy spacing between certain valence orbitals is severely underestimated.
Effect of second-order coupling on optical bistability in a hybrid optomechanical system
Asghari Nejad, Ali; Baghshahi, Hamid R.; Askari, Hassan R.
2017-11-01
We theoretically investigate an optomechanical system consisting of two coupled cavities, a bare optomechanical cavity and a traditional one. An optical parametric amplifier (OPA) is placed inside the traditional cavity. Optomechanical cavity has an oscillating mirror and a fixed one. In addition to the first order coupling between mechanical resonator of the system and the radiation pressure of optomechanical cavity, we consider a second order interaction between them. The evaluation of the system's behavior shows bistability in the mean photon number of optomechanical cavity. Our results show that, the second order coupling leads to degenerate solutions for the equation of mean photon number of optomechanical cavity. We see that the strength of SOC can change the domain of bistability region of optomechanical cavity. Also, properties of the field driving OPA have remarkable effects on the stability of optomechanical cavity. Moreover, we show that the domain of bistability region can be modified by changing of optical properties of the system.
Second-order two-scale method for bending behaviors of composite plate with periodic configuration
International Nuclear Information System (INIS)
Zhu Guoqing; Cui Junzhi
2010-01-01
In this paper, the second-order two-scale analysis method for bending behaviors of the plate made from composites with 3-D periodic configuration is presented by means of construction way. It can capture the microscopic 3-D mechanics behaviors caused from 3-D micro-structures. First, directly starting from the 3-D elastic plate model of composite materials with 3-D periodic configuration, three cell models are defined, and correspondingly the three classes of cell functions only defined on 3 normalized cells are constructed. And then, the effective homogenization parameters of composites are calculated from those local functions, it leads to a 2-D homogenized laminar plate problem. Next, to solve it the homogenization solution is obtained. Finally, the second-order two-scale solution is constructed from the micro-cell functions and the homogenization solution.
Tripartite entanglement from the cavity with second-order harmonic generation
Zhai, Shuqin; Yang, Rongguo; Fan, Daihe; Guo, Juan; Liu, Kui; Zhang, Junxiang; Gao, Jiangrui
2008-07-01
In this paper, tripartite entanglement among the two pump fields and the second-order harmonic field is established in the process of type-II second-order harmonic generation (SHG) with a triply resonant optical cavity below threshold. A sufficient inseparability criterion for continuous-variable tripartite entanglement proposed by van Loock and Furusawa is used to evaluate the degree of the quadrature-phase-amplitude correlations between the three modes. The dependence of the entanglement on the pump parameter and analysis frequency is also discussed. It is shown that the best entanglement appears at the appropriate pump power and analysis frequency. These three entangled states with different frequencies generated directly from a simple SHG process make the scheme useful for the application in quantum communication and network.
Directory of Open Access Journals (Sweden)
Chelladurai CALLINS CHRISTIYANA
2013-12-01
Full Text Available This work proposes a new method called Center Symmetric Local Binary Pattern Grey Level Co-occurrence Matrix (CSLBPGLCM for the purpose of extracting second order statistical texture features in ultrasound kidney images. These features are then feed into ultrasound kidney images retrieval system for the point of medical applications. This new GLCM matrix combines the benefit of CSLBP and conventional GLCM. The main intention of this CSLBPGLCM is to reduce the number of grey levels in an image by not simply accumulating the grey levels but incorporating another statistical texture feature in it. The proposed approach is cautiously evaluated in ultrasound kidney images retrieval system and has been compared with conventional GLCM. It is experimentally proved that the proposed method increases the retrieval efficiency, accuracy and reduces the time complexity of ultrasound kidney images retrieval system by means of second order statistical texture features.
Effect of pressure on the second-order Raman scattering intensities of zincblende semiconductors
Energy Technology Data Exchange (ETDEWEB)
Trallero-Giner, C.; Syassen, K. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)
2010-01-15
A microscopic description of the two-phonon scattering intensities in direct-gap zincblende-type semiconductors as a function of hydrostatic pressure and for non-resonant excitation is presented. The calculations were performed according to the electron-two-phonon deformation potential interaction for the {gamma}{sub 1} and {gamma}{sub 15} components of the Raman tensor. It is shown that the effect of pressure on the Raman scattering cross-section exhibits a complex behavior according to the contribution of the acoustical or optical phonons to the overtones and combinations. Second-order scattering intensities via acoustical modes could decrease or increase with increasing hydrostatic pressure, while for combinations or overtones of optical phonons a decreasing intensity is obtained. Calculations of the effect of pressure on second-order Raman intensities are compared to experimental results for ZnTe. (Abstract Copyright [2010], Wiley Periodicals, Inc.)
A Novel Second-Order All-Pass Filter Using Square-Root Domain Blocks
Directory of Open Access Journals (Sweden)
S. Surav Yilmaz
2013-04-01
Full Text Available In this study, a new second order all-pass filter is synthesized in the square-root domain by using the state-space method. The proposed second order all-pass filter is constituted by current mirrors, current sources, current-mode square-root circuits and capacitors. The pole frequency of the filter can be tuned electronically by varying the values of the current sources of this circuit. The filter is simulated in PSpice using 0.35um CMOS technology parameters. Quality factor of the circuit is selected as 5 and supply voltage is set to 2.7V. The simulation results show that the proposed circuit has the merits of electronic tunability. We also performed noise, THD and Monte-Carlo analyses. Various simulation results are presented to show the effectiveness of the proposed circuit.
Periodic Solution of Second-Order Hamiltonian Systems with a Change Sign Potential on Time Scales
Directory of Open Access Journals (Sweden)
You-Hui Su
2009-01-01
Full Text Available This paper is concerned with the second-order Hamiltonian system on time scales 𝕋 of the form uΔΔ(ρ(t+μb(t|u(t|μ−2u(t+∇¯H(t,u(t=0, Δ-a.e. t∈[0,T]𝕋 , u(0−u(T=uΔ(ρ(0−uΔ(ρ(T=0, where 0,T∈𝕋. By using the minimax methods in critical theory, an existence theorem of periodic solution for the above system is established. As an application, an example is given to illustrate the result. This is probably the first time the existence of periodic solutions for second-order Hamiltonian system on time scales has been studied by critical theory.
Method of construction of the Riemann function for a second-order hyperbolic equation
Aksenov, A. V.
2017-12-01
A linear hyperbolic equation of the second order in two independent variables is considered. The Riemann function of the adjoint equation is shown to be invariant with respect to the fundamental solutions transformation group. Symmetries and symmetries of fundamental solutions of the Euler-Poisson-Darboux equation are found. The Riemann function is constructed with the aid of fundamental solutions symmetries. Examples of the application of the algorithm for constructing Riemann function are given.
Dynamics of second order in time evolution equations with state-dependent delay
Czech Academy of Sciences Publication Activity Database
Chueshov, I.; Rezunenko, Oleksandr
123-124, č. 1 (2015), s. 126-149 ISSN 0362-546X R&D Projects: GA ČR GAP103/12/2431 Institutional support: RVO:67985556 Keywords : Second order evolution equations * State dependent delay * Nonlinear plate * Finite-dimensional attractor Subject RIV: BD - Theory of Information Impact factor: 1.125, year: 2015 http://library.utia.cas.cz/separaty/2015/AS/rezunenko-0444708.pdf
Solvability of second-order boundary-value problems at resonance involving integral conditions
Directory of Open Access Journals (Sweden)
Yujun Cui
2012-03-01
Full Text Available This article concerns the second-order differential equation with integral boundary conditions $$displaylines{ x''(t=f(t,x(t,x'(t,quad tin (0,1,cr x(0=int_0^1x(sdalpha(s,quad x(1=int_0^1x(sdeta(s. }$$ Under the resonance conditions, we construct a projector and then applying coincidence degree theory to establish the existence of solutions.
On the Aubin Property of Critical Points to Perturbed Second-Order Cone Programs
Czech Academy of Sciences Publication Activity Database
Outrata, Jiří; Ramírez, H. C.
2011-01-01
Roč. 21, č. 3 (2011), s. 798-823 ISSN 1052-6234 R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506 Keywords : second-order cone programming * strong regularity * Aubin property Subject RIV: BA - General Mathematics Impact factor: 1.629, year: 2011 http://library.utia.cas.cz/separaty/2011/MTR/outrata-0364167.pdf
On oscillations of solutions to second-order linear delay differential equations
Czech Academy of Sciences Publication Activity Database
Opluštil, Z.; Šremr, Jiří
2013-01-01
Roč. 20, č. 1 (2013), s. 65-94 ISSN 1072-947X Institutional support: RVO:67985840 Keywords : linear second-order delay differential equation * oscillatory solution Subject RIV: BA - General Mathematics Impact factor: 0.340, year: 2013 http://www.degruyter.com/view/j/gmj.2013.20.issue-1/gmj-2013-0001/gmj-2013-0001. xml ?format=INT
Remark on zeros of solutions of second-order linear ordinary differential equations
Czech Academy of Sciences Publication Activity Database
Dosoudilová, M.; Lomtatidze, Alexander
2016-01-01
Roč. 23, č. 4 (2016), s. 571-577 ISSN 1072-947X Institutional support: RVO:67985840 Keywords : second-order linear equation * zeros of solutions * periodic boundary value problem Subject RIV: BA - General Mathematics Impact factor: 0.290, year: 2016 https://www.degruyter.com/view/j/gmj.2016.23.issue-4/gmj-2016-0052/gmj-2016-0052. xml
Chen, Zhangxin; Ewing, Richard E.
1996-01-01
Multigrid algorithms for nonconforming and mixed finite element methods for second order elliptic problems on triangular and rectangular finite elements are considered. The construction of several coarse-to-fine intergrid transfer operators for nonconforming multigrid algorithms is discussed. The equivalence between the nonconforming and mixed finite element methods with and without projection of the coefficient of the differential problems into finite element spaces is described.
A Novel Control Approach Based on Second Order Sliding Modes & Its Application to Hydraulic Drives
DEFF Research Database (Denmark)
Schmidt, Lasse; Andersen, Torben Ole; Pedersen, Henrik C.
2013-01-01
accuracy to be reached. In this paper a novel control approach based on second order sliding modes utilizing the idea of the power rate reaching law is introduced. Dependent on parameters the proposed controller may preserve the main features of sliding controls, while at the same time avoiding control...... chattering. Simulation studies confirm the announced properties when applied to a hydraulic drive model subjected to strong variations in supply pressure and friction....
Giuseppe De Nadai; Paolo Pianca
2007-01-01
In this note using the rules of stochastic dominance of the second order and the recent cumulative prospect theory for classified, according to their performance, a set of common funds. The criteria used are closely linked to the preferences of decision maker and refer to either hypothesis of aversion and of seeking to risk both hypothesis on the sign of derived second of the function which characterizes the losses and gains.
The Discursive Dimension of Second-order Elections: The Case of Czech Regional Elections 2012
Czech Academy of Sciences Publication Activity Database
Vašát, Petr; Čermák, Daniel
2016-01-01
Roč. 16, č. 2 (2016), s. 121-153 ISSN 1582-456X R&D Projects: GA ČR GAP404/12/0714 Institutional support: RVO:68378025 Keywords : second-order elections theory * discursive dimension of SOE * regional elections Subject RIV: AO - Sociology, Demography Impact factor: 0.458, year: 2016 http://www.sar.org.ro/polsci/?p=1248
Monotone methods for solving a boundary value problem of second order discrete system
Directory of Open Access Journals (Sweden)
Wang Yuan-Ming
1999-01-01
Full Text Available A new concept of a pair of upper and lower solutions is introduced for a boundary value problem of second order discrete system. A comparison result is given. An existence theorem for a solution is established in terms of upper and lower solutions. A monotone iterative scheme is proposed, and the monotone convergence rate of the iteration is compared and analyzed. The numerical results are given.
Learning to fear a second-order stimulus following vicarious learning
Reynolds, G; Field, AP; Askew, C
2015-01-01
Vicarious fear learning refers to the acquisition of fear via observation of the fearful responses of others. The present study aims to extend current knowledge by exploring whether second-order vicarious fear learning can be demonstrated in children. That is, whether vicariously learnt fear responses for one stimulus can be elicited in a second stimulus associated with that initial stimulus. Results demonstrated that children’s (5–11 years) fear responses for marsupials and caterpillars incr...
ERRATUM: ON THE AUBIN PROPERTY OF CRITICAL POINTS TO PERTURBED SECOND-ORDER CONE PROGRAMS
Czech Academy of Sciences Publication Activity Database
Opazo, F.; Outrata, Jiří; Ramírez, H. C.
2017-01-01
Roč. 27, č. 3 (2017), s. 2143-2151 ISSN 1052-6234 R&D Projects: GA ČR GA15-00735S Institutional support: RVO:67985556 Keywords : second-order cone programming * Aubin property * nondegeneracy Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 1.968, year: 2016 http://library.utia.cas.cz/separaty/2017/MTR/outrata-0481868.pdf
Directory of Open Access Journals (Sweden)
Siniša Miličić
2013-01-01
Full Text Available We study the oscillation of all solutions of a general class of forced second-order differential equations, where their second derivative is not necessarily a continuous function and the coefficients of the main equation may be discontinuous. Our main results are not included in the previously published known oscillation criteria of interval type. Many examples and consequences are presented illustrating the main results.
Directory of Open Access Journals (Sweden)
Bapurao C. Dhage
2015-01-01
Full Text Available In this article we prove the existence and approximations of solutions of periodic boundary-value problems of second-order ordinary nonlinear hybrid differential equations. We rely our results on Dhage iteration principle or method embodied in a recent hybrid fixed point theorem of Dhage (2014 in partially ordered normed linear spaces. Our resutls are proved under weaker continuity and Lipschitz conditions. An example illustrates the theory developed in this article.
International Nuclear Information System (INIS)
Karimov, Ruslan Kh; Kozhevnikova, Larisa M
2010-01-01
The first mixed problem with homogeneous Dirichlet boundary condition and initial function with compact support is considered for quasilinear second order parabolic equations in a cylindrical domain D=(0,∞)xΩ. Upper bounds are obtained, which give the rate of decay of the solutions as t→∞ as a function of the geometry of the unbounded domain Ω subset of R n , n≥2. Bibliography: 18 titles.
Class of unconditionally stable second-order implicit schemes for hyperbolic and parabolic equations
International Nuclear Information System (INIS)
Lui, H.C.
The linearized Burgers equation is considered as a model u/sub t/ tau/sub x/ = bu/sub xx/, where the subscripts t and x denote the derivatives of the function u with respect to time t and space x; a and b are constants (b greater than or equal to 0). Numerical schemes for solving the equation are described that are second-order accurate, unconditionally stable, and dissipative of higher order. (U.S.)
On oscillations of solutions to second-order linear delay differential equations
Czech Academy of Sciences Publication Activity Database
Opluštil, Z.; Šremr, Jiří
2013-01-01
Roč. 20, č. 1 (2013), s. 65-94 ISSN 1072-947X Institutional support: RVO:67985840 Keywords : linear second-order delay differential equation * oscillatory solution Subject RIV: BA - General Mathematics Impact factor: 0.340, year: 2013 http://www.degruyter.com/view/j/gmj.2013.20.issue-1/gmj-2013-0001/gmj-2013-0001.xml?format=INT
Thandapani, Ethiraju; Kannan, Manju; Pinelas, Sandra
2016-01-01
In this paper, we present some sufficient conditions for the oscillation of all solutions of a second order forced impulsive delay differential equation with damping term. Three factors-impulse, delay and damping that affect the interval qualitative properties of solutions of equations are taken into account together. The results obtained in this paper extend and generalize some of the the known results for forced impulsive differential equations. An example is provided to illustrate the main result.
The solutions of second-order linear differential systems with constant delays
Diblík, Josef; Svoboda, Zdeněk
2017-07-01
The representations of solutions to initial problems for non-homogenous n-dimensional second-order differential equations with delays x″(t )-2 A x'(t -τ )+(A2+B2)x (t -2 τ )=f (t ) by means of special matrix delayed functions are derived. Square matrices A and B are commuting and τ > 0. Derived representations use what is called a delayed exponential of a matrix and results generalize some of known results previously derived for homogenous systems.
Second-order Born approximation for the ionization of molecules by electron and positron impact
Energy Technology Data Exchange (ETDEWEB)
Dal Cappello, C. [Universite Paul Verlaine-Metz, Laboratoire de Physique Moleculaire et des Collisions, Institut Jean Barriol (FR2843), 1 Boulevard Arago, F-57078 Metz Cedex 3 (France); Rezkallah, Z.; Houamer, S. [Laboratoire de Physique Quantique et Systemes Dynamiques, Departement de Physique, Faculte des Sciences Universite Ferhat Abbas, Setif 19000 (Algeria); Charpentier, I. [Universite Paul Verlaine-Metz, Laboratoire de Physique et Mecanique des Materiaux UMR 7554, Ile du Saulcy, F-57045 Metz Cedex 1 (France); Hervieux, P. A. [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 Rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Ruiz-Lopez, M. F. [Nancy-University, Equipe de Chimie et Biochimie Theoriques, UMR CNRS-UHP 7565, BP 239, F-54506 Vandoeuvre-les-Nancy (France); Dey, R. [Max-Planck Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Roy, A. C. [School of Mathematical Sciences, Ramakrishna Mission Vivekananda University, Belur Math 711202, West Bengal (India)
2011-09-15
Second-order Born approximation is applied to study the ionization of molecules. The initial and final states are described by single-center wave functions. For the initial state a Gaussian wave function is used while for the ejected electron it is a distorted wave. Results of the present model are compared with recent (e,2e) experiments on the water molecule. Preliminary results are also presented for the ionization of the thymine molecule by electrons and positrons.
Discrete Ordinates Approximations to the First- and Second-Order Radiation Transport Equations
Fan, W C; Powell, J L
2002-01-01
The conventional discrete ordinates approximation to the Boltzmann transport equation can be described in a matrix form. Specifically, the within-group scattering integral can be represented by three components: a moment-to-discrete matrix, a scattering cross-section matrix and a discrete-to-moment matrix. Using and extending these entities, we derive and summarize the matrix representations of the second-order transport equations.
Error analysis of Newmark's method for the second order equation with inhomogeneous term
International Nuclear Information System (INIS)
Chiba, F.; Kako, T.
2000-01-01
For the second order time evolution equation with a general dissipation term, we introduce a recurrence relation of Newmark's method. Deriving an energy inequality from this relation, we consider the stability and the convergence criteria of Newmark's method. We treat a dissipation term under the assumption that the coefficient-damping matrix is constant in time and non-negative. We can relax however the assumptions for the dissipation and the rigidity matrices to be arbitrary symmetric matrices. (author)
Second Order Sliding Mode Control with Prescribed Convergence Law for Electro-Hydraulic Drives
DEFF Research Database (Denmark)
Schmidt, Lasse; Andersen, Torben Ole; Pedersen, Henrik C.
2013-01-01
This paper discusses the application of second order sliding modes for position tracking control of electro-hydraulic valve-cylinder drives (VCD’s). The target is to introduce increased tracking- and transient performance compared to conventional linear approaches, without extending the number...... of tuning parameters. The proposed controller utilizes basic component knowledge commonly available from data sheets, as well as pressure-, valve position-, piston position- and velocity measurements. Results demonstrate improved position tracking- and transient performance, compared to a linear control...
Maximum principles for boundary-degenerate second-order linear elliptic differential operators
Feehan, Paul M. N.
2012-01-01
We prove weak and strong maximum principles, including a Hopf lemma, for smooth subsolutions to equations defined by linear, second-order, partial differential operators whose principal symbols vanish along a portion of the domain boundary. The boundary regularity property of the smooth subsolutions along this boundary vanishing locus ensures that these maximum principles hold irrespective of the sign of the Fichera function. Boundary conditions need only be prescribed on the complement in th...
A novel nonlinear adaptive filter using a pipelined second-order Volterra recurrent neural network.
Zhao, Haiquan; Zhang, Jiashu
2009-12-01
To enhance the performance and overcome the heavy computational complexity of recurrent neural networks (RNN), a novel nonlinear adaptive filter based on a pipelined second-order Volterra recurrent neural network (PSOVRNN) is proposed in this paper. A modified real-time recurrent learning (RTRL) algorithm of the proposed filter is derived in much more detail. The PSOVRNN comprises of a number of simple small-scale second-order Volterra recurrent neural network (SOVRNN) modules. In contrast to the standard RNN, these modules of a PSOVRNN can be performed simultaneously in a pipelined parallelism fashion, which can lead to a significant improvement in its total computational efficiency. Moreover, since each module of the PSOVRNN is a SOVRNN in which nonlinearity is introduced by the recursive second-order Volterra (RSOV) expansion, its performance can be further improved. Computer simulations have demonstrated that the PSOVRNN performs better than the pipelined recurrent neural network (PRNN) and RNN for nonlinear colored signals prediction and nonlinear channel equalization. However, the superiority of the PSOVRNN over the PRNN is at the cost of increasing computational complexity due to the introduced nonlinear expansion of each module.
First and second order approximate reliability analysis methods using evidence theory
International Nuclear Information System (INIS)
Zhang, Z.; Jiang, C.; Wang, G.G.; Han, X.
2015-01-01
The first order approximate reliability method (FARM) and second order approximate reliability method (SARM) are formulated based on evidence theory in this paper. The proposed methods can significantly improve the computational efficiency for evidence-theory-based reliability analysis, while generally provide sufficient precision. First, the most probable focal element (MPFE), an important concept as the most probable point (MPP) in probability-theory-based reliability analysis, is searched using a uniformity approach. Subsequently, FARM approximates the limit-state function around the MPFE using the linear Taylor series, while SARM approximates it using the quadratic Taylor series. With the first and second order approximations, the reliability interval composed of the belief measure and the plausibility measure is efficiently obtained for FARM and SARM, respectively. Two simple problems with explicit expressions and one engineering application of vehicle frontal impact are presented to demonstrate the effectiveness of the proposed methods. - Highlights: • The first order approximate reliability method using evidence theory is proposed. • The second order approximate reliability method using evidence theory is proposed. • The proposed methods can significantly improve the computational efficiency. • The proposed methods can provide sufficient accuracy for general engineering problems
Effect of Second-Order Hydrodynamics on Floating Offshore Wind Turbines: Preprint
Energy Technology Data Exchange (ETDEWEB)
Roald, L.; Jonkman, J.; Robertson, A,; Chokani, N.
2013-07-01
Offshore winds are generally stronger and more consistent than winds on land, making the offshore environment attractive for wind energy development. A large part of the offshore wind resource is however located in deep water, where floating turbines are the only economical way of harvesting the energy. The design of offshore floating wind turbines relies on the use of modeling tools that can simulate the entire coupled system behavior. At present, most of these tools include only first-order hydrodynamic theory. However, observations of supposed second-order hydrodynamic responses in wave-tank tests performed by the DeepCwind consortium suggest that second-order effects might be critical. In this paper, the methodology used by the oil and gas industry has been modified to apply to the analysis of floating wind turbines, and is used to assess the effect of second-order hydrodynamics on floating offshore wind turbines. The method relies on combined use of the frequency-domain tool WAMIT and the time-domain tool FAST. The proposed assessment method has been applied to two different floating wind concepts, a spar and a tension-leg-platform (TLP), both supporting the NREL 5-MW baseline wind turbine. Results showing the hydrodynamic forces and motion response for these systems are presented and analysed, and compared to aerodynamic effects.
Formation tracking control for time-delayed multi-agent systems with second-order dynamics
Directory of Open Access Journals (Sweden)
Liang Han
2017-02-01
Full Text Available In this paper, formation tracking control problems for second-order multi-agent systems (MASs with time-varying delays are studied, specifically those where the position and velocity of followers are designed to form a time-varying formation while tracking those of the leader. A neighboring relative state information based formation tracking protocol with an unknown gain matrix and time-varying delays is presented. The formation tracking problems are then transformed into asymptotically stable problems. Based on the Lyapunov-Krasovskii functional approach, conditions sufficient for second-order MASs with time-varying delays to realize formation tracking are examined. An approach to obtain the unknown gain matrix is given and, since neighboring relative velocity information is difficult to measure in practical applications, a formation tracking protocol with time-varying delays using only neighboring relative position information is introduced. The proposed results can be used on target enclosing problems for MASs with second-order dynamics and time-varying delays. An application for target enclosing by multiple unmanned aerial vehicles (UAVs is given to demonstrate the feasibility of theoretical results.
Charge and finite size corrections for virtual photon spectra in second order Born approximation
International Nuclear Information System (INIS)
Durgapal, P.
1982-01-01
The purpose of this work is to investigate the effects of finite nuclear size and charge on the spectrum of virtual photons emitted when a relativistic electron is scattered in the field of an atomic nucleus. The method consisted in expanding the scattering cross section in terms of integrals over the nuclear inelastic form factor with a kernel which was evaluated in second order Born approximation and was derived from the elastic-electron scattering form factor. The kernel could be evaluated analytically provided the elastic form factor contained only poles. For this reason the author used a Yukawa form factor. Before calculating the second order term the author studied the first order term containing finite size effects in the inelastic form factor. The author observed that the virtual photon spectrum is insensitive to the details of the inelastic distribution over a large range of energies and depends only on the transition radius. This gave the author the freedom of choosing an inelastic distribution for which the form factor has only poles and the author chose a modified form of the exponential distribution, which enabled the author to evaluate the matrix element analytically. The remaining integral over the physical momentum transfer was performed numerically. The author evaluated the virtual photon spectra for E1 and M1 transitions for a variety of electron energies using several nuclei and compared the results with the distorted wave calculations. Except for low energy and high Z, the second order results compared well with the distorted wave calculations
Directory of Open Access Journals (Sweden)
Hui Chen
2014-01-01
Full Text Available Due to the variety of second-order data being generated by modern instruments and various mathematical algorithms being available for analysis purposes, second-order calibration is gaining widespread acceptance by analytical community. It has the so-called second-order advantage; that is, it enables concentration and spectral profiles of sample components to be extracted even in the presence of unexpected interferences. A comprehensive performance comparison of alternating trilinear decomposition (ATLD and its two variants, that is, alternating penalty trilinear decomposition (APTLD and self-weighted trilinear decomposition (SWATLD, was presented in this paper. The experiment was based on the simultaneous determination of three dihydroxybenzenes, that is, catechol, hydroquinone, and resorcinol, by excitation-emission matrix fluorescence (EEMF spectroscopy. Two special measures, that is, the consistency (COS between the resolved and actual profiles and the mean of recovery, were used for evaluation. The optimal result was obtained by the APTLD model with five components. No perceptible difference on the speed of convergence was found. It indicates that EEMF linked with the APTLD algorithm can serve as a potential tool of quantifying dihydroxybenzenes simultaneously in environmental samples.
CMB in the river frame and gauge invariance at second order
Roldan, Omar
2018-03-01
Gauge invariance: the Sachs-Wolfe formula describing the Cosmic Microwave Background (CMB) temperature anisotropies is one of the most important relations in cosmology. Despite its importance, the gauge invariance of this formula has only been discussed at first order. Here we discuss the subtle issue of second-order gauge transformations on the CMB. By introducing two rules (needed to handle the subtle issues), we prove the gauge invariance of the second-order Sachs-Wolfe formula and provide several compact expressions which can be useful for the study of gauge transformations on cosmology. Our results go beyond a simple technicality: we discuss from a physical point of view several aspects that improve our understanding of the CMB. We also elucidate how crucial it is to understand gauge transformations on the CMB in order to avoid errors and/or misconceptions as occurred in the past. The river frame: we introduce a cosmological frame which we call the river frame. In this frame, photons and any object can be thought as fishes swimming in the river and relations are easily expressed in either the metric or the covariant formalism then ensuring a transparent geometric meaning. Finally, our results show that the river frame is useful to make perturbative and non-perturbative analysis. In particular, it was already used to obtain the fully nonlinear generalization of the Sachs-Wolfe formula and is used here to describe second-order perturbations.
Zaunders, John; Jing, Junmei; Leipold, Michael; Maecker, Holden; Kelleher, Anthony D; Koch, Inge
2016-01-01
Many methods have been described for automated clustering analysis of complex flow cytometry data, but so far the goal to efficiently estimate multivariate densities and their modes for a moderate number of dimensions and potentially millions of data points has not been attained. We have devised a novel approach to describing modes using second order polynomial histogram estimators (SOPHE). The method divides the data into multivariate bins and determines the shape of the data in each bin based on second order polynomials, which is an efficient computation. These calculations yield local maxima and allow joining of adjacent bins to identify clusters. The use of second order polynomials also optimally uses wide bins, such that in most cases each parameter (dimension) need only be divided into 4-8 bins, again reducing computational load. We have validated this method using defined mixtures of up to 17 fluorescent beads in 16 dimensions, correctly identifying all populations in data files of 100,000 beads in analysis, and up to 65 subpopulations of PBMC in 33-dimensional CyTOF data, showing its usefulness in discovery research. SOPHE has the potential to greatly increase efficiency of analysing complex mixtures of cells in higher dimensions. © 2015 International Society for Advancement of Cytometry.
Second-order coding rates for pure-loss bosonic channels
Wilde, Mark M.; Renes, Joseph M.; Guha, Saikat
2016-03-01
A pure-loss bosonic channel is a simple model for communication over free-space or fiber-optic links. More generally, phase-insensitive bosonic channels model other kinds of noise, such as thermalizing or amplifying processes. Recent work has established the classical capacity of all of these channels, and furthermore, it is now known that a strong converse theorem holds for the classical capacity of these channels under a particular photon-number constraint. The goal of the present paper is to initiate the study of second-order coding rates for these channels, by beginning with the simplest one, the pure-loss bosonic channel. In a second-order analysis of communication, one fixes the tolerable error probability and seeks to understand the back-off from capacity for a sufficiently large yet finite number of channel uses. We find a lower bound on the maximum achievable code size for the pure-loss bosonic channel, in terms of the known expression for its capacity and a quantity called channel dispersion. We accomplish this by proving a general "one-shot" coding theorem for channels with classical inputs and pure-state quantum outputs which reside in a separable Hilbert space. The theorem leads to an optimal second-order characterization when the channel output is finite-dimensional, and it remains an open question to determine whether the characterization is optimal for the pure-loss bosonic channel.
Second-order optimality conditions for problems with C1 data
Ginchev, Ivan; Ivanov, Vsevolod I.
2008-04-01
In this paper we obtain second-order optimality conditions of Karush-Kuhn-Tucker type and Fritz John one for a problem with inequality constraints and a set constraint in nonsmooth settings using second-order directional derivatives. In the necessary conditions we suppose that the objective function and the active constraints are continuously differentiable, but their gradients are not necessarily locally Lipschitz. In the sufficient conditions for a global minimum we assume that the objective function is differentiable at and second-order pseudoconvex at , a notion introduced by the authors [I. Ginchev, V.I. Ivanov, Higher-order pseudoconvex functions, in: I.V. Konnov, D.T. Luc, A.M. Rubinov (Eds.), Generalized Convexity and Related Topics, in: Lecture Notes in Econom. and Math. Systems, vol. 583, Springer, 2007, pp. 247-264], the constraints are both differentiable and quasiconvex at . In the sufficient conditions for an isolated local minimum of order two we suppose that the problem belongs to the class C1,1. We show that they do not hold for C1 problems, which are not C1,1 ones. At last a new notion parabolic local minimum is defined and it is applied to extend the sufficient conditions for an isolated local minimum from problems with C1,1 data to problems with C1 one.
CMB anisotropies at second order III: bispectrum from products of the first-order perturbations
Nitta, Daisuke; Bartolo, Nicola; Matarrese, Sabino; Riotto, Antonio
2009-01-01
We calculate the bispectrum of the Cosmic Microwave Background (CMB) temperature anisotropies induced by the second-order fluctuations in the Boltzmann equation. In this paper, which is one of a series of papers on the numerical calculation of the bispectrum from the second-order fluctuations, we consider the terms that are products of the first-order perturbations, and leave intrinsically second-order terms and perturbations in the recombination history to the subsequent papers. We show that the bispectrum has the maximum signal in the squeezed triangles, similar to the local-type primordial bispectrum, as both types generate non-linearities via products of the first-order terms in position space. However, detailed calculations show that their shapes are sufficiently different: the cross-correlation coefficient reaches 0.5 at the maximum multipole of l_{max}~ 200, and then weakens to 0.3 at l_{max}~ 2000. The differences in shape arise from (i) the way the acoustic oscillations affect the bispectrum, and (ii...
Meng, Shukai; Mo, Yu L.
2001-09-01
Image segmentation is one of the most important operations in many image analysis problems, which is the process that subdivides an image into its constituents and extracts those parts of interest. In this paper, we present a new second order difference gray-scale image segmentation algorithm based on cellular neural networks. A 3x3 CNN cloning template is applied, which can make smooth processing and has a good ability to deal with the conflict between the capability of noise resistance and the edge detection of complex shapes. We use second order difference operator to calculate the coefficients of the control template, which are not constant but rather depend on the input gray-scale values. It is similar to Contour Extraction CNN in construction, but there are some different in algorithm. The result of experiment shows that the second order difference CNN has a good capability in edge detection. It is better than Contour Extraction CNN in detail detection and more effective than the Laplacian of Gauss (LOG) algorithm.
Second-order accurate kinetic schemes for the ultra-relativistic Euler equations
International Nuclear Information System (INIS)
Kunik, Matthias; Qamar, Shamsul; Warnecke, Gerald
2003-01-01
A second-order accurate kinetic scheme for the numerical solution of the relativistic Euler equations is presented. These equations describe the flow of a perfect fluid in terms of the particle density n, the spatial part of the four-velocity u and the pressure p. The kinetic scheme, is based on the well-known fact that the relativistic Euler equations are the moments of the relativistic Boltzmann equation of the kinetic theory of gases when the distribution function is a relativistic Maxwellian. The kinetic scheme consists of two phases, the convection phase (free-flight) and collision phase. The velocity distribution function at the end of the free-flight is the solution of the collisionless transport equation. The collision phase instantaneously relaxes the distribution to the local Maxwellian distribution. The fluid dynamic variables of density, velocity, and internal energy are obtained as moments of the velocity distribution function at the end of the free-flight phase. The scheme presented here is an explicit method and unconditionally stable. The conservation laws of mass, momentum and energy as well as the entropy inequality are everywhere exactly satisfied by the solution of the kinetic scheme. The scheme also satisfies positivity and L 1 -stability. The scheme can be easily made into a total variation diminishing method for the distribution function through a suitable choice of the interpolation strategy. In the numerical case studies the results obtained from the first- and second-order kinetic schemes are compared with the first- and second-order upwind and central schemes. We also calculate the experimental order of convergence and numerical L 1 -stability of the scheme for smooth initial data
Second-Order Free-Riding on Antisocial Punishment Restores the Effectiveness of Prosocial Punishment
Directory of Open Access Journals (Sweden)
Attila Szolnoki
2017-10-01
Full Text Available Economic experiments have shown that punishment can increase public goods game contributions over time. However, the effectiveness of punishment is challenged by second-order free-riding and antisocial punishment. The latter implies that noncooperators punish cooperators, while the former implies unwillingness to shoulder the cost of punishment. Here, we extend the theory of cooperation in the spatial public goods game by considering four competing strategies, which are traditional cooperators and defectors, as well as cooperators who punish defectors and defectors who punish cooperators. We show that if the synergistic effects are high enough to sustain cooperation based on network reciprocity alone, antisocial punishment does not deter public cooperation. Conversely, if synergistic effects are low and punishment is actively needed to sustain cooperation, antisocial punishment does is viable, but only if the cost-to-fine ratio is low. If the costs are relatively high, cooperation again dominates as a result of spatial pattern formation. Counterintuitively, defectors who do not punish cooperators, and are thus effectively second-order free-riding on antisocial punishment, form an active layer around punishing cooperators, which protects them against defectors that punish cooperators. A stable three-strategy phase that is sustained by the spontaneous emergence of cyclic dominance is also possible via the same route. The microscopic mechanism behind the reported evolutionary outcomes can be explained by the comparison of invasion rates that determine the stability of subsystem solutions. Our results reveal an unlikely evolutionary escape from adverse effects of antisocial punishment, and they provide a rationale for why second-order free-riding is not always an impediment to the evolutionary stability of punishment.
A second-order unconstrained optimization method for canonical-ensemble density-functional methods
Nygaard, Cecilie R.; Olsen, Jeppe
2013-03-01
A second order converging method of ensemble optimization (SOEO) in the framework of Kohn-Sham Density-Functional Theory is presented, where the energy is minimized with respect to an ensemble density matrix. It is general in the sense that the number of fractionally occupied orbitals is not predefined, but rather it is optimized by the algorithm. SOEO is a second order Newton-Raphson method of optimization, where both the form of the orbitals and the occupation numbers are optimized simultaneously. To keep the occupation numbers between zero and two, a set of occupation angles is defined, from which the occupation numbers are expressed as trigonometric functions. The total number of electrons is controlled by a built-in second order restriction of the Newton-Raphson equations, which can be deactivated in the case of a grand-canonical ensemble (where the total number of electrons is allowed to change). To test the optimization method, dissociation curves for diatomic carbon are produced using different functionals for the exchange-correlation energy. These curves show that SOEO favors symmetry broken pure-state solutions when using functionals with exact exchange such as Hartree-Fock and Becke three-parameter Lee-Yang-Parr. This is explained by an unphysical contribution to the exact exchange energy from interactions between fractional occupations. For functionals without exact exchange, such as local density approximation or Becke Lee-Yang-Parr, ensemble solutions are favored at interatomic distances larger than the equilibrium distance. Calculations on the chromium dimer are also discussed. They show that SOEO is able to converge to ensemble solutions for systems that are more complicated than diatomic carbon.
Second-Order Free-Riding on Antisocial Punishment Restores the Effectiveness of Prosocial Punishment
Szolnoki, Attila; Perc, Matjaž
2017-10-01
Economic experiments have shown that punishment can increase public goods game contributions over time. However, the effectiveness of punishment is challenged by second-order free-riding and antisocial punishment. The latter implies that noncooperators punish cooperators, while the former implies unwillingness to shoulder the cost of punishment. Here, we extend the theory of cooperation in the spatial public goods game by considering four competing strategies, which are traditional cooperators and defectors, as well as cooperators who punish defectors and defectors who punish cooperators. We show that if the synergistic effects are high enough to sustain cooperation based on network reciprocity alone, antisocial punishment does not deter public cooperation. Conversely, if synergistic effects are low and punishment is actively needed to sustain cooperation, antisocial punishment does is viable, but only if the cost-to-fine ratio is low. If the costs are relatively high, cooperation again dominates as a result of spatial pattern formation. Counterintuitively, defectors who do not punish cooperators, and are thus effectively second-order free-riding on antisocial punishment, form an active layer around punishing cooperators, which protects them against defectors that punish cooperators. A stable three-strategy phase that is sustained by the spontaneous emergence of cyclic dominance is also possible via the same route. The microscopic mechanism behind the reported evolutionary outcomes can be explained by the comparison of invasion rates that determine the stability of subsystem solutions. Our results reveal an unlikely evolutionary escape from adverse effects of antisocial punishment, and they provide a rationale for why second-order free-riding is not always an impediment to the evolutionary stability of punishment.
Di G. Sigalotti, L.; Klapp, J.
1997-03-01
A new second-order Eulerian code is compared with a version of the TREESPH code formulated by Hernquist & Katz (1989ApJS...70..419H) for the standard isothermal collapse test. The results indicate that both codes produce a very similar evolution ending with the formation of a protostellar binary system. Contrary to previous first-order calculations, the binary forms by direct fragmentation, i.e., without the occurrence of an intermediate bar configuration. A similar trend was also found in recent second-order Eulerian calculations (Myhill & Boss 1993ApJS...89..345M), suggesting that it is a result of the decreased numerical diffusion associated with the new second-order schemes. The results have also implications on the differences between the finite difference methods and the particle method SPH, raised by Monaghan & Lattanzio (1986A&A...158..207M) for this problem. In particular, the Eulerian calculation does not result in a run-away collapse of the fragments, and as found in the TREESPH evolution, they also show a clear tendency to get closer together. In agreement with previous SPH calculations (Monaghan & Lattanzio 1986A&A...158..207M), the results of the long term evolution with code TREESPH show that the gravitational interaction between the two fragments may become important, and eventually induce the binary to coalesce. However, most recent SPH calculations (Bate, Bonnell & Price 1995MNRAS.277..362B ) indicate that the two fragments, after having reached a minimum separation distance, do not merge but continue to orbit each other.
Directory of Open Access Journals (Sweden)
Jessica C Lee
Full Text Available In human causal learning, excitatory and inhibitory learning effects can sometimes be found in the same paradigm by altering the learning conditions. This study aims to explore whether learning in the feature negative paradigm can be dissociated by emphasising speed over accuracy. In two causal learning experiments, participants were given a feature negative discrimination in which the outcome caused by one cue was prevented by the addition of another. Participants completed training trials either in a self-paced fashion with instructions emphasising accuracy, or under strict time constraints with instructions emphasising speed. Using summation tests in which the preventative cue was paired with another causal cue, participants in the accuracy groups correctly rated the preventative cue as if it reduced the probability of the outcome. However, participants in the speed groups rated the preventative cue as if it increased the probability of the outcome. In Experiment 1, both speed and accuracy groups later judged the same cue to be preventative in a reasoned inference task. Experiment 2 failed to find evidence of similar dissociations in retrospective revaluation (release from overshadowing vs. mediated extinction or learning about a redundant cue (blocking vs. augmentation. However in the same experiment, the tendency for the accuracy group to show conditioned inhibition and the speed group to show second-order conditioning was consistent even across sub-sets of the speed and accuracy groups with equivalent accuracy in training, suggesting that second-order conditioning is not merely a consequence of poorer acquisition. This dissociation mirrors the trade-off between second-order conditioning and conditioned inhibition observed in animal conditioning when training is extended.
Second-order sign-preserving conservative interpolation (remapping) on general grids
Margolin, L G
2003-01-01
An accurate conservative interpolation (remapping) algorithm is an essential component of most arbitrary Lagrangian-Eulerian (ALE) methods. In this paper we describe a local remapping algorithm for a positive scalar function. This algorithm is second-order accurate, conservative, and sign preserving. The algorithm is based on estimating the mass exchanged between cells at their common interface, and so is equally applicable to structured and unstructured grids. We construct the algorithm in a series of steps, clearly delineating the assumptions and errors made at each step. We validate our theory with a suite of numerical examples, analyzing the results from the viewpoint of accuracy and order of convergence.
Normal-mode-based analysis of electron plasma waves with second-order Hermitian formalism
Ramos, J. J.; White, R. L.
2018-03-01
The classic problem of the dynamic evolution and Landau damping of linear Langmuir electron waves in a collisionless plasma with Maxwellian background is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-invariant solution for any initial-value problem. Examples are given for specific initial conditions that illustrate different behaviors of the Landau-damped macroscopic moments of the perturbations.
International Nuclear Information System (INIS)
Brandt, H.E.
1983-01-01
A new exact symmetry is proved for the complete second-order nonlinear conductivity tensor of an unmagnetized relativistic turbulent plasma. The symmetry is not limited to principal parts. If Cerenkov resonance is ignored, the new symmetry reduces to the well-known symmetry related to the Manley--Rowe relations, crossing symmetry, and nondissipation of the principal part of the nonlinear current. Also, a new utilitarian representation for the complete tensor is obtained in which all derivatives are removed and the pole structure is clearly exhibited
Iterative oscillation results for second-order differential equations with advanced argument
Directory of Open Access Journals (Sweden)
Irena Jadlovska
2017-07-01
Full Text Available This article concerns the oscillation of solutions to a linear second-order differential equation with advanced argument. Sufficient oscillation conditions involving limit inferior are given which essentially improve known results. We base our technique on the iterative construction of solution estimates and some of the recent ideas developed for first-order advanced differential equations. We demonstrate the advantage of our results on Euler-type advanced equation. Using MATLAB software, a comparison of the effectiveness of newly obtained criteria as well as the necessary iteration length in particular cases are discussed.
On an inequality of Kolmogorov type for a second-order difference expression
Directory of Open Access Journals (Sweden)
Evans WD
1999-01-01
Full Text Available In this paper we discuss an inequality of Kolmogorov type for the square of a second-order formally symmetric difference expression in the limit point case. A connection between the existence of the inequality and the Hellinger–Nevanlinna function associated with the difference expression is established and it is shown that the best constant in the inequality is determined by the behaviour of the -function. Analytical and computational results are obtained for specific classes of problems. Also necessary and sufficient conditions for the powers of the difference expression to be partially separated are given.
Convergence Results on a Second-Order Rational Difference Equation with Quadratic Terms
Directory of Open Access Journals (Sweden)
Chan DM
2009-01-01
Full Text Available We investigate the global behavior of the second-order difference equation , where initial conditions and all coefficients are positive. We find conditions on under which the even and odd subsequences of a positive solution converge, one to zero and the other to a nonnegative number; as well as conditions where one of the subsequences diverges to infinity and the other either converges to a positive number or diverges to infinity. We also find initial conditions where the solution monotonically converges to zero and where it diverges to infinity.
Effect of Second-Order Hydrodynamics on a Floating Offshore Wind Turbine
Energy Technology Data Exchange (ETDEWEB)
Roald, L.; Jonkman, J.; Robertson, A.
2014-05-01
The design of offshore floating wind turbines uses design codes that can simulate the entire coupled system behavior. At the present, most codes include only first-order hydrodynamics, which induce forces and motions varying with the same frequency as the incident waves. Effects due to second- and higher-order hydrodynamics are often ignored in the offshore industry, because the forces induced typically are smaller than the first-order forces. In this report, first- and second-order hydrodynamic analysis used in the offshore oil and gas industry is applied to two different wind turbine concepts--a spar and a tension leg platform.
Kepner, Gordon R
2010-04-13
The numerous natural phenomena that exhibit saturation behavior, e.g., ligand binding and enzyme kinetics, have been approached, to date, via empirical and particular analyses. This paper presents a mechanism-free, and assumption-free, second-order differential equation, designed only to describe a typical relationship between the variables governing these phenomena. It develops a mathematical model for this relation, based solely on the analysis of the typical experimental data plot and its saturation characteristics. Its utility complements the traditional empirical approaches. For the general saturation curve, described in terms of its independent (x) and dependent (y) variables, a second-order differential equation is obtained that applies to any saturation phenomena. It shows that the driving factor for the basic saturation behavior is the probability of the interactive site being free, which is described quantitatively. Solving the equation relates the variables in terms of the two empirical constants common to all these phenomena, the initial slope of the data plot and the limiting value at saturation. A first-order differential equation for the slope emerged that led to the concept of the effective binding rate at the active site and its dependence on the calculable probability the interactive site is free. These results are illustrated using specific cases, including ligand binding and enzyme kinetics. This leads to a revised understanding of how to interpret the empirical constants, in terms of the variables pertinent to the phenomenon under study. The second-order differential equation revealed the basic underlying relations that describe these saturation phenomena, and the basic mathematical properties of the standard experimental data plot. It was shown how to integrate this differential equation, and define the common basic properties of these phenomena. The results regarding the importance of the slope and the new perspectives on the empirical
Team Resilience as a Second-Order Emergent State: A Theoretical Model and Research Directions
Directory of Open Access Journals (Sweden)
Clint Bowers
2017-08-01
Full Text Available Resilience has been recognized as an important phenomenon for understanding how individuals overcome difficult situations. However, it is not only individuals who face difficulties; it is not uncommon for teams to experience adversity. When they do, they must be able to overcome these challenges without performance decrements.This manuscript represents a theoretical model that might be helpful in conceptualizing this important construct. Specifically, it describes team resilience as a second-order emergent state. We also include research propositions that follow from the model.
Adaptive Second-Order Total Variation: An Approach Aware of Slope Discontinuities
Lenzen, Frank
2013-01-01
Total variation (TV) regularization, originally introduced by Rudin, Osher and Fatemi in the context of image denoising, has become widely used in the field of inverse problems. Two major directions of modifications of the original approach were proposed later on. The first concerns adaptive variants of TV regularization, the second focuses on higher-order TV models. In the present paper, we combine the ideas of both directions by proposing adaptive second-order TV models, including one anisotropic model. Experiments demonstrate that introducing adaptivity results in an improvement of the reconstruction error. © 2013 Springer-Verlag.
Weak Second Order Explicit Stabilized Methods for Stiff Stochastic Differential Equations
Abdulle, Assyr
2013-01-01
We introduce a new family of explicit integrators for stiff Itô stochastic differential equations (SDEs) of weak order two. These numerical methods belong to the class of one-step stabilized methods with extended stability domains and do not suffer from the step size reduction faced by standard explicit methods. The family is based on the standard second order orthogonal Runge-Kutta-Chebyshev (ROCK2) methods for deterministic problems. The convergence, meansquare, and asymptotic stability properties of the methods are analyzed. Numerical experiments, including applications to nonlinear SDEs and parabolic stochastic partial differential equations are presented and confirm the theoretical results. © 2013 Society for Industrial and Applied Mathematics.
Instrumentation amplifier implements second-order active low-pass filter with high gain factor
International Nuclear Information System (INIS)
Blomqvist, Kim H; Eskelinen, Pekka; Sepponen, Raimo E
2011-01-01
A single-ended second-order active low-pass filter can simultaneously provide high gain factor and dc voltage subtraction. This makes it possible to reduce the number of components and signal processing stages needed in an application where small voltage changes are measured on the top of large dc voltage masked by a large amplitude oscillating carrier. The filter described in this paper is constructed from a conventional 3-op-amp instrumentation amplifier and five passive circuit elements. (technical design note)
Second-Order Moller-Plesset Perturbation Theory for Molecular Dirac-Hartree-Fock Wave Functions
Dyall, Kenneth G.; Arnold, James O. (Technical Monitor)
1994-01-01
Moller-Plesset perturbation theory is developed to second order for a selection of Kramers restricted Dirac-Hartree-Fock closed and open-shell reference wave functions. The open-shell wave functions considered are limited to those with no more than two electrons in open shells, but include the case of a two-configuration SCF reference. Denominator shifts are included in the style of Davidson's OPT2 method. An implementation which uses unordered integrals with labels is presented, and results are given for a few test cases.
International Nuclear Information System (INIS)
Rutkis, M; Jurgis, A; Kampars, V; Vembris, A; Tokmakovs, A; Kokars, V
2007-01-01
Maximal achieved second order non linear optical (NLO) efficiency of the PMMA based host - guest systems containing eight dimethylaminobenzylidene -1, 3 - indandione (DMABI) related chromophores have been analysed. Two contradicting sets of NLO chromophore figure of merit (FOM) equations were tested. One of them predicts that NLO efficiency of the poled polymer host -guest film is proportional to ground state dipole d 33 ∼ 1/μ g , another to d 33 ∼ 1/μ g . The best correlations for the maximal achieved nonlinearity were obtained with second set of FOM, especially if high ground state dipole (μ g > 7D) chromofores are included in analysis
Directory of Open Access Journals (Sweden)
Fairouz Zouyed
2015-01-01
Full Text Available This paper discusses the inverse problem of determining an unknown source in a second order differential equation from measured final data. This problem is ill-posed; that is, the solution (if it exists does not depend continuously on the data. In order to solve the considered problem, an iterative method is proposed. Using this method a regularized solution is constructed and an a priori error estimate between the exact solution and its regularized approximation is obtained. Moreover, numerical results are presented to illustrate the accuracy and efficiency of this method.
An efficient second-order SQP method for structural topology optimization
DEFF Research Database (Denmark)
Rojas Labanda, Susana; Stolpe, Mathias
2016-01-01
This article presents a Sequential Quadratic Programming (SQP) solver for structural topology optimization problems named TopSQP. The implementation is based on the general SQP method proposed in Morales et al. J Numer Anal 32(2):553–579 (2010) called SQP+. The topology optimization problem...... nonlinear solvers IPOPT and SNOPT. Numerical experiments on a large set of benchmark problems show good performance of TopSQP in terms of number of function evaluations. In addition, the use of second-order information helps to decrease the objective function value....
Stochastic bounded consensus of second-order multi-agent systems in noisy environment
International Nuclear Information System (INIS)
Ren Hong-Wei; Deng Fei-Qi
2017-01-01
This paper investigates the stochastic bounded consensus of leader-following second-order multi-agent systems in a noisy environment. It is assumed that each agent received the information of its neighbors corrupted by noises and time delays. Based on the graph theory, stochastic tools, and the Lyapunov function method, we derive the sufficient conditions under which the systems would reach stochastic bounded consensus in mean square with the protocol we designed. Finally, a numerical simulation is illustrated to check the effectiveness of the proposed algorithms. (paper)
Exceptional points near first- and second-order quantum phase transitions.
Stránský, Pavel; Dvořák, Martin; Cejnar, Pavel
2018-01-01
We study the impact of quantum phase transitions (QPTs) on the distribution of exceptional points (EPs) of the Hamiltonian in the complex-extended parameter domain. Analyzing first- and second-order QPTs in the Lipkin-Meshkov-Glick model we find an exponentially and polynomially close approach of EPs to the respective critical point with increasing size of the system. If the critical Hamiltonian is subject to random perturbations of various kinds, the averaged distribution of EPs close to the critical point still carries decisive information on the QPT type. We therefore claim that properties of the EP distribution represent a parametrization-independent signature of criticality in quantum systems.
Internal crisis in a second-order non-linear non-autonomous electronic oscillator
International Nuclear Information System (INIS)
Stavrinides, S.G.; Deliolanis, N.C.; Miliou, A.N.; Laopoulos, Th.; Anagnostopoulos, A.N.
2008-01-01
The internal crisis of a second-order non-linear non-autonomous chaotic electronic circuit is studied. The phase portraits consist of two interacting sub-attractors, a chaotic and a periodic one. Maximal Lyapunov exponents were calculated, for both the periodic and the chaotic waveforms, in order to confirm their nature. Transitions between the chaotic and the periodic sub-attractors become more frequent by increasing the circuit driving frequency. The frequency distribution of the corresponding laminar lengths and their average values indicate that an internal crisis takes place in this circuit, manifested in the intermittent behaviour of the corresponding orbits
Umezawa, Hirohito; Jackson, Matthew; Lebel, Olivier; Nunzi, Jean-Michel; Sabat, Ribal Georges
2016-10-01
The second-order nonlinear optical coefficients of thin films of mexylaminotriazine-functionalized azobenzene molecular glass derivatives were measured using second harmonic generation. The thin films were poled using a custom corona poling set-up and the second harmonic light from a pulsed 1064-nm laser was detected. Four out of the six tested compounds showed optical nonlinearity and a maximum coefficient of 75 pm/V was obtained. The time dependence of the nonlinear coefficients was studied under ambient light and under dark; the second harmonic generation intensity stayed constant for thiazole-containing derivatives while a significant decay was measured for the other compounds.
The Dhage Iteration Principle for Coupled PBVPs of Nonlinear Second Order Differential Equations
Directory of Open Access Journals (Sweden)
Bapurao C. Dhage
2015-05-01
Full Text Available The present paper proposes a new monotone iteration principle for the existence as well as approximations of the coupled solutions for a coupled periodic boundary value problem of second order ordinary nonlinear differential equations. An algorithm for the coupled solutions is developed and it is shown that the sequences of successive approximations defined in a certain way converge monotonically to the coupled solutions of the related differential equations under some suitable hybrid conditions. A numerical example is also indicated to illustrate the abstract theory developed in the paper. We claim that the method as well as the results of this paper are new to literature on nonlinear analysis and applications.
A new simple model for composite fading channels: Second order statistics and channel capacity
Yilmaz, Ferkan
2010-09-01
In this paper, we introduce the most general composite fading distribution to model the envelope and the power of the received signal in such fading channels as millimeter wave (60 GHz or above) fading channels and free-space optical channels, which we term extended generalized-K (EGK) composite fading distribution. We obtain the second-order statistics of the received signal envelope characterized by the EGK composite fading distribution. Expressions for probability density function, cumulative distribution function, level crossing rate and average fade duration, moments, amount of fading and average capacity are derived. Numerical and computer simulation examples validate the accuracy of the presented mathematical analysis. © 2010 IEEE.
Energy Technology Data Exchange (ETDEWEB)
Ravikumar, C. [Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram-695 015, Kerala (India); Hubert Joe, I., E-mail: hubertjoe@gmail.com [Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram-695 015, Kerala (India); Sajan, D. [Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram-695 015, Kerala (India)
2010-03-24
FT-Raman and IR spectra of the nonlinear optic (NLO) crystal, acetoacetanilide have been recorded and analyzed. The detailed interpretation of the vibrational spectra has been carried out with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The various intramolecular interactions that is responsible for the stabilization of the molecule was revealed by natural bond orbital analysis. The Kurtz and Perry powder reflection technique appeared to be very effective in studies of second-order nonlinear optical properties of the molecule.
Semantic Characterisations of Second-Order Computability over the Real Numbers
DEFF Research Database (Denmark)
Korovina, Margarita V.; Kudinov, Oleg V.
2001-01-01
equality and prove theorems which connect computable operators and real-valued functionals with validity of finite σ-formulas. This research was supported in part by the RFBR (grants N 99-01-00485, N 00-01-00810) and by the Siberian Division of RAS (a grant for young researchers, 2000)......We propose semantic characterisations of second-order computability over the reals based on σ-definability theory. Notions of computability for operators and real-valued functionals defined on the class of continuous functions are introduced via domain theory. We consider the reals with and without...
Second order sliding power control for a variable speed-constant frequency energy conversion system
International Nuclear Information System (INIS)
Valenciaga, Fernando
2010-01-01
This paper presents a decoupled active and reactive power control for a variable speed-constant frequency generation system based on a brushless doubly fed reluctance machine. The control design is approached using multi-input second order sliding techniques which are specially appropriate to deal with nonlinear system models in presence of external disturbances and model inaccuracies. The controller synthesized through this theoretical framework presents very good robustness features, a finite reaching time and a chattering-free behavior. The performance of the closed loop system is assessed through representative computer simulations.
Second order sliding power control for a variable speed-constant frequency energy conversion system
Energy Technology Data Exchange (ETDEWEB)
Valenciaga, Fernando, E-mail: fval@ing.unlp.edu.a [CONICET, Laboratorio de Electronica Industrial Control e Instrumentacion (LEICI), Facultad de Ingenieria, Universidad Nacional de La Plata, CC.91, C.P. 1900 La Plata (Argentina)
2010-12-15
This paper presents a decoupled active and reactive power control for a variable speed-constant frequency generation system based on a brushless doubly fed reluctance machine. The control design is approached using multi-input second order sliding techniques which are specially appropriate to deal with nonlinear system models in presence of external disturbances and model inaccuracies. The controller synthesized through this theoretical framework presents very good robustness features, a finite reaching time and a chattering-free behavior. The performance of the closed loop system is assessed through representative computer simulations.
Bond index: relation to second-order density matrix and charge fluctuations
International Nuclear Information System (INIS)
Giambiagi, M.S. de; Giambiagi, M.; Jorge, F.E.
1985-01-01
It is shown that, in the same way as the atomic charge is an invariant built from the first-order density matrix, the closed-shell generalized bond index is an invariant associated with the second-order reduced density matrix. The active charge of an atom (sum of bond indices) is shown to be the sum of all density correlation functions between it and the other atoms in the molecule; similarly, the self-charge is the fluctuation of its total charge. (Author) [pt
On Passband and Stopband CIC Improvements Using a Second Order IIR Filter
Gordana Jovanovic Dolecek; Alfonso Fernandez-Vazquez
2012-01-01
This paper proposes an efficient second order IIR filter which considerably improves the passband as well as the stopband of the Cascaded-Integrator-Comb (CIC) filter. Using the polyphase decomposition of the proposed filte, all filtering can be moved to a lower rate, which is D times less than the high input rate, where D is the decimation factor. The overall phase response of the compensated CIC is approximately linear in the passband. The design parameters are the number of cascaded CIC fi...
Second-order shaped pulsed for solid-state quantum computation
Energy Technology Data Exchange (ETDEWEB)
Sengupta, Pinaki [Los Alamos National Laboratory
2008-01-01
We present the construction and detailed analysis of highly optimized self-refocusing pulse shapes for several rotation angles. We characterize the constructed pulses by the coefficients appearing in the Magnus expansion up to second order. This allows a semianalytical analysis of the performance of the constructed shapes in sequences and composite pulses by computing the corresponding leading-order error operators. Higher orders can be analyzed with the numerical technique suggested by us previously. We illustrate the technique by analyzing several composite pulses designed to protect against pulse amplitude errors, and on decoupling sequences for potentially long chains of qubits with on-site and nearest-neighbor couplings.
Second-order differential-delay equation to describe a hybrid bistable device
Vallee, R.; Dubois, P.; Cote, M.; Delisle, C.
1987-08-01
The problem of a dynamical system with delayed feedback, a hybrid bistable device, characterized by n response times and described by an nth-order differential-delay equation (DDE) is discussed. Starting from a linear-stability analysis of the DDE, the effects of the second-order differential terms on the position of the first bifurcation and on the frequency of the resulting self-oscillation are shown. The effects of the third-order differential terms on the first bifurcation are also considered. Experimental results are shown to support the linear analysis.
A new implementation of the second-order polarization propagator approximation (SOPPA)
DEFF Research Database (Denmark)
Packer, Martin J.; Dalskov, Erik K.; Enevoldsen, Thomas
1996-01-01
We present a new implementation of the second-order polarization propagator approximation (SOPPA) using a direct linear transformation approach, in which the SOPPA equations are solved iteratively. This approach has two important advantages over its predecessors. First, the direct linear...... and triplet transitions for benzene and naphthalene. The results compare well with experiment and CASPT2 values, calculated with identical basis sets and molecular geometries. This indicates that SOPPA can provide reliable values for excitation energies and response properties for relatively large molecular...
On Passband and Stopband CIC Improvements Using a Second Order IIR Filter
Directory of Open Access Journals (Sweden)
Gordana Jovanovic Dolecek
2012-03-01
Full Text Available This paper proposes an efficient second order IIR filter which considerably improves the passband as well as the stopband of the Cascaded-Integrator-Comb (CIC filter. Using the polyphase decomposition of the proposed filte, all filtering can be moved to a lower rate, which is D times less than the high input rate, where D is the decimation factor. The overall phase response of the compensated CIC is approximately linear in the passband. The design parameters are the number of cascaded CIC filter N, the decimator factor D, the passband frequency wp, and a weighted parameter a.
The effects of brief-stimulus presentations in fixed-ratio second-order schedules
Cohen, Steven L.; Calisto, George
1981-01-01
Pigeons' responses were reinforced according to a three-component multiple schedule. In Component 1, key pecks produced food according to a fixed-ratio second-order schedule with fixed-ratio units. Here, a fixed number of fixed-ratio units produced food, and the brief stimulus terminating each unit also accompanied food. Responses in Component 2 produced food on an identical schedule except that the brief stimulus was not paired with food. Component 3 contained a simple fixed-ratio schedule w...
DEFF Research Database (Denmark)
Chen, X.; Cui, W.; Jensen, Jørgen Juncher
2003-01-01
The theory and typical numerical results of a second order nonlinear hydroelastic analysis of floating bodies are presented in a series of papers in which only nonlinearity in fluids is considered. Under the assumption of linear fluid, the hydroelastic analysis methods of nonlinear structure...... are introduced in this paper. With the examples of the motion and displacement reponses of a floating plate undergoing large vertical deflections in multidirectional waves, the analysis method of the couple action between the vertical deflections in multidirectional waves, the analysis method of the couple...
Non-commutative gauge gravity: second-order correction and scalar particle creation
Energy Technology Data Exchange (ETDEWEB)
Zaim, Slimane [Departement de Physique, Faculte des Sciences, Universite de Batna (Algeria); Khodja, Lamine, E-mail: zaimslimane@yahoo.f [Departement de Physique, Faculte des Sciences Exactes, Universite Mentouri, Constantine (Algeria)
2010-05-01
We construct a non-commutative gauge theory for a charged scalar field and verify its invariance under local Poincare and general coordinate transformations. We derive a general Klein-Gordon equation up to the second order of the non-commutativity parameter using the general modified field equation. As an application, we choose the Bianchi I universe and use the Seiberg-Witten maps to obtain the deformed non-commutative metric and study a particle production process. We show that non-commutativity plays the same role as an electric field, gravity and chemical potential.
Mixed FEM for Second Order Elliptic Problems on Polygonal Meshes with BEM-Based Spaces
Efendiev, Yalchin
2014-01-01
We present a Boundary Element Method (BEM)-based FEM for mixed formulations of second order elliptic problems in two dimensions. The challenge, we would like to address, is a proper construction of H(div)-conforming vector valued trial functions on arbitrary polygonal partitions of the domain. The proposed construction generates trial functions on polygonal elements which inherit some of the properties of the unknown solution. In the numerical realization, the relevant local problems are treated by means of boundary integral formulations. We test the accuracy of the method on two model problems. © 2014 Springer-Verlag.
Second-order domain derivative of normal-dependent boundary integrals
Balzer, Jonathan
2010-03-17
Numerous reconstruction tasks in (optical) surface metrology allow for a variational formulation. The occurring boundary integrals may be interpreted as shape functions. The paper is concerned with the second-order analysis of such functions. Shape Hessians of boundary integrals are considered difficult to find analytically because they correspond to third-order derivatives of an, in a sense equivalent, domain integral. We complement previous results by considering cost functions depending explicitly on the surface normal. The correctness and practicability of our calculations are verified in the context of a Newton-type shape reconstruction method. © 2010 Birkhäuser / Springer Basel AG.
A Stable Clock Error Model Using Coupled First and Second Order Gauss-Markov Processes
Carpenter, Russell; Lee, Taesul
2008-01-01
Long data outages may occur in applications of global navigation satellite system technology to orbit determination for missions that spend significant fractions of their orbits above the navigation satellite constellation(s). Current clock error models based on the random walk idealization may not be suitable in these circumstances, since the covariance of the clock errors may become large enough to overflow flight computer arithmetic. A model that is stable, but which approximates the existing models over short time horizons is desirable. A coupled first- and second-order Gauss-Markov process is such a model.
Boeije, M. F. J.; Maschek, M.; Miao, X. F.; Thang, N. V.; van Dijk, N. H.; Brück, E.
2017-05-01
Temperature dependent high-resolution x-ray diffraction measurements were used to characterize the magneto-elastic ferromagnetic transition of (Fe,Mn)2(P,Si,B) compounds. Across the transition, apart from a change in lattice parameters across the transition, the internal coordinates of Mn and Fe also change. This intrinsic degree of freedom allows Fe in the tetrahedral coordination to decrease the two interatomic distances with the 2c position and increase the two distances with the two 1b position, while the Fe-Mn distance remains constant. For Mn in the square based pyramidal coordination, all interatomic distances effectively remain constant. Electron density plots show that for second-order transitions, the observed changes are smaller and continuously extending over a wide temperature range in the ferromagnetic and paramagnetic states, due to short-range order. This study shows that the mechanism behind the phase transition in Fe2P-based materials is an isostructural transition that is equal for both first- and second-order transitions.
Second-order hydrodynamics and universality in non-conformal holographic fluids
Energy Technology Data Exchange (ETDEWEB)
Kleinert, Philipp; Probst, Jonas [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)
2016-12-19
We study second-order hydrodynamic transport in strongly coupled non-conformal field theories with holographic gravity duals in asymptotically anti-de Sitter space. We first derive new Kubo formulae for five second-order transport coefficients in non-conformal fluids in (3+1) dimensions. We then apply them to holographic RG flows induced by scalar operators of dimension Δ=3. For general background solutions of the dual bulk geometry, we find explicit expressions for the five transport coefficients at infinite coupling and show that a specific combination, H̃=2ητ{sub π}−2(κ−κ{sup ∗})−λ{sub 2}, always vanishes. We prove analytically that the Haack-Yarom identity H=2ητ{sub π}−4λ{sub 1}−λ{sub 2}=0, which is known to be true for conformal holographic fluids at infinite coupling, also holds when taking into account leading non-conformal corrections. The numerical results we obtain for two specific families of RG flows suggest that H vanishes regardless of conformal symmetry. Our work provides further evidence that the Haack-Yarom identity H=0 may be universally satisfied by strongly coupled fluids.
Second order formalism for spin (1/2) fermions and Compton scattering
International Nuclear Information System (INIS)
Delgado-Acosta, E. G.; Napsuciale, Mauro; Rodriguez, Simon
2011-01-01
We develop a second order formalism for massive spin 1/2 fermions based on the projection over Poincare invariant subspaces in the ((1/2),0)+(0,(1/2)) representation of the homogeneous Lorentz group. Using the U(1) em gauge principle we obtain a second order description for the electromagnetic interactions of a spin 1/2 fermion with two free parameters, the gyromagnetic factor g and a parameter ξ related to odd-parity Lorentz structures. We calculate Compton scattering in this formalism. In the particular case g=2, ξ=0, and for states with well-defined parity, we recover Dirac results. In general, we find the correct classical limit and a finite value r c 2 for the forward differential cross section, independent of the photon energy and of the value of the parameters g and ξ. The differential cross section vanishes at high energies for all g, ξ except in the forward direction. The total cross section at high energies vanishes only for g=2, ξ=0. We argue that this formalism is more convenient than Dirac theory in the description of low energy electromagnetic properties of baryons and illustrate the point with the proton case.
Second-Order Nonlinear Analysis of Steel Tapered Beams Subjected to Span Loading
Directory of Open Access Journals (Sweden)
Ali Hadidi
2014-03-01
Full Text Available A second-order elastic analysis of tapered steel members with I-shaped sections subjected to span distributed and concentrated loadings is developed. Fixed end forces and moments as well as exact stiffness matrix of tapered Timoshenko-Euler beam are obtained with exact geometrical properties of sections. The simultaneous action of bending moment, shear, and axial force including P−δ effects is also considered in the analysis. A computer code has been developed in MATLAB software using a power series method to solve governing second-order differential equation of equilibrium with variable coefficients for beams with distributed span loading. A generalized matrix condensation technique is then utilized for analysis of beams with concentrated span loadings. The accuracy and efficiency of the results of the proposed method are verified through comparing them to those obtained from other approaches such as finite element methods, which indicates the robustness and time saving of this method even for large scale frames with tapered members.
Second-Order Controllability of Multi-Agent Systems with Multiple Leaders
Liu, Bo; Shi, Yun-Tao; Su, Hou-Sheng; Han, Xiao
2016-05-01
This paper proposes a new second-order continuous-time multi-agent model and analyzes the controllability of second-order multi-agent system with multiple leaders based on the asymmetric topology. This paper considers the more general case: velocity coupling topology is different from location coupling topology. Some sufficient and necessary conditions are presented for the controllability of the system with multiple leaders. In addition, the paper studies the controllability of the system with velocity damping gain. Simulation results are given to illustrate the correctness of theoretical results. Supported by the National Natural Science Foundation of China under Grant Nos. 61473129, 61304049, 61104140, 61473002, the Beijing Natural Science Foundation Program under Grant No. 4132021, the Program for New Century Excellent Talents in University from Chinese Ministry of Education under Grant NCET-12-0215, “The-Great-Wall-Scholar” Candidate Training-Plan of North China University of Technology (NX130), and the Plan Training Project of Excellent Young Teacher of North China University of Technology (NX132), the Fundamental Research Funds for the Central Universities, (HUST: Grant No. 2015TS025), the Fundamental Research Funds for the Central Universities (WUT: Grant No. 2015VI015)
Learning to fear a second-order stimulus following vicarious learning.
Reynolds, Gemma; Field, Andy P; Askew, Chris
2017-04-01
Vicarious fear learning refers to the acquisition of fear via observation of the fearful responses of others. The present study aims to extend current knowledge by exploring whether second-order vicarious fear learning can be demonstrated in children. That is, whether vicariously learnt fear responses for one stimulus can be elicited in a second stimulus associated with that initial stimulus. Results demonstrated that children's (5-11 years) fear responses for marsupials and caterpillars increased when they were seen with fearful faces compared to no faces. Additionally, the results indicated a second-order effect in which fear-related learning occurred for other animals seen together with the fear-paired animal, even though the animals were never observed with fearful faces themselves. Overall, the findings indicate that for children in this age group vicariously learnt fear-related responses for one stimulus can subsequently be observed for a second stimulus without it being experienced in a fear-related vicarious learning event. These findings may help to explain why some individuals do not recall involvement of a traumatic learning episode in the development of their fear of a specific stimulus.
A generalized LSTM-like training algorithm for second-order recurrent neural networks.
Monner, Derek; Reggia, James A
2012-01-01
The long short term memory (LSTM) is a second-order recurrent neural network architecture that excels at storing sequential short-term memories and retrieving them many time-steps later. LSTM's original training algorithm provides the important properties of spatial and temporal locality, which are missing from other training approaches, at the cost of limiting its applicability to a small set of network architectures. Here we introduce the generalized long short-term memory(LSTM-g) training algorithm, which provides LSTM-like locality while being applicable without modification to a much wider range of second-order network architectures. With LSTM-g, all units have an identical set of operating instructions for both activation and learning, subject only to the configuration of their local environment in the network; this is in contrast to the original LSTM training algorithm, where each type of unit has its own activation and training instructions. When applied to LSTM architectures with peephole connections, LSTM-g takes advantage of an additional source of back-propagated error which can enable better performance than the original algorithm. Enabled by the broad architectural applicability of LSTM-g, we demonstrate that training recurrent networks engineered for specific tasks can produce better results than single-layer networks. We conclude that LSTM-g has the potential to both improve the performance and broaden the applicability of spatially and temporally local gradient-based training algorithms for recurrent neural networks. Copyright © 2011 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Kalpeshkumar Rohitbhai Patil
2016-10-01
Full Text Available Proper synchronization of Distributed Generator with grid and its performance in grid-connected mode relies on fast and precise estimation of phase and amplitude of the fundamental component of grid voltage. However, the accuracy with which the frequency is estimated is dependent on the type of grid voltage abnormalities and structure of the phase-locked loop or frequency locked loop control schemes. Among various control schemes, second-order generalized integrator based frequency- locked loop (SOGI-FLL is reported to have the most promising performance. It tracks the frequency of grid voltage accurately even when grid voltage is characterized by sag, swell, harmonics, imbalance, frequency variations etc. However, estimated frequency contains low frequency oscillations in case when sensed grid-voltage has a dc offset. This paper presents a modified dual second-order generalized integrator frequency-locked loop (MDSOGI-FLL for three-phase systems to cope with the non-ideal three-phase grid voltages having all type of abnormalities including the dc offset. The complexity in control scheme is almost the same as the standard dual SOGI-FLL, but the performance is enhanced. Simulation results show that the proposed MDSOGI-FLL is effective under all abnormal grid voltage conditions. The results are validated experimentally to justify the superior performance of MDSOGI-FLL under adverse conditions.
The second-order description of rotational non-equilibrium effects in polyatomic gases
Myong, Rho Shin
2017-11-01
The conventional description of gases is based on the physical laws of conservation (mass, momentum, and energy) in conjunction with the first-order constitutive laws, the two-century old so-called Navier-Stokes-Fourier (NSF) equation based on a critical assumption made by Stokes in 1845 that the bulk viscosity vanishes. While the Stokes' assumption is certainly legitimate in the case of dilute monatomic gases, ever increasing evidences, however, now indicate that such is not the case, in particular, in the case of polyatomic gases-like nitrogen and carbon dioxide-far-from local thermal equilibrium. It should be noted that, from room temperature acoustic attenuation data, the bulk viscosity for carbon dioxide is three orders of magnitude larger than its shear viscosity. In this study, this fundamental issue in compressible gas dynamics is revisited and the second-order constitutive laws are derived by starting from the Boltzmann-Curtiss kinetic equation. Then the topology of the second-order nonlinear coupled constitutive relations in phase space is investigated. Finally, the shock-vortex interaction problem where the strong interaction of two important thermal (translational and rotational) non-equilibrium phenomena occurs is considered in order to highlight the rotational non-equilibrium effects in polyatomic gases. This work was supported by the National Research Foundation of South Korea (NRF 2017-R1A2B2-007634).
Assessment of Patellar Tendon Reflex Responses Using Second-Order System Characteristics
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Brett D. Steineman
2016-01-01
Full Text Available Deep tendon reflex tests, such as the patellar tendon reflex (PTR, are widely accepted as simple examinations for detecting neurological disorders. Despite common acceptance, the grading scales remain subjective, creating an opportunity for quantitative measures to improve the reliability and efficacy of these tests. Previous studies have demonstrated the usefulness of quantified measurement variables; however, little work has been done to correlate experimental data with theoretical models using entire PTR responses. In the present study, it is hypothesized that PTR responses may be described by the exponential decay rate and damped natural frequency of a theoretical second-order system. Kinematic data was recorded from both knees of 45 subjects using a motion capture system and correlation analysis found that the mean R2 value was 0.99. Exponential decay rate and damped natural frequency ranges determined from the sample population were −5.61 to −1.42 and 11.73 rad/s to 14.96 rad/s, respectively. This study confirmed that PTR responses strongly correlate to a second-order system and that exponential decay rate and undamped natural frequency are novel measurement variables to accurately measure PTR responses. Therefore, further investigation of these measurement variables and their usefulness in grading PTR responses is warranted.
Analysis of heart rate variability signal in meditation using second-order difference plot
Goswami, Damodar Prasad; Tibarewala, Dewaki Nandan; Bhattacharya, Dilip Kumar
2011-06-01
In this article, the heart rate variability signal taken from subjects practising different types of meditations have been investigated to find the underlying similarity among them and how they differ from the non-meditative condition. Four different groups of subjects having different meditation techniques are involved. The data have been obtained from the Physionet and also collected with our own ECG machine. For data analysis, the second order difference plot is applied. Each of the plots obtained from the second order differences form a single cluster which is nearly elliptical in shape except for some outliers. In meditation, the axis of the elliptical cluster rotates anticlockwise from the cluster formed from the premeditation data, although the amount of rotation is not of the same extent in every case. This form study reveals definite and specific changes in the heart rate variability of the subjects during meditation. All the four groups of subjects followed different procedures but surprisingly the resulting physiological effect is the same to some extent. It indicates that there is some commonness among all the meditative techniques in spite of their apparent dissimilarity and it may be hoped that each of them leads to the same result as preached by the masters of meditation. The study shows that meditative state has a completely different physiology and that it can be achieved by any meditation technique we have observed. Possible use of this tool in clinical setting such as in stress management and in the treatment of hypertension is also mentioned.
Conditional budgets of second-order statistics in nonpremixed and premixed turbulent combustion
Macart, Jonathan F.; Grenga, Temistocle; Mueller, Michael E.
2016-11-01
Combustion heat release modifies or introduces a number of new terms to the balance equations for second-order turbulence statistics (turbulent kinetic energy, scalar variance, etc.) compared to incompressible flow. A major modification is a significant increase in viscosity and dissipation in the high-temperature combustion products, but new terms also appear due to density variation and gas expansion (dilatation). Previous scaling analyses have hypothesized that dilatation effects are important in turbulent premixed combustion but are unimportant in turbulent nonpremixed combustion. To explore this hypothesis, a series of DNS calculations have been performed in the low Mach number limit for spatially evolving turbulent planar jet flames of hydrogen and air in both premixed and nonpremixed configurations. Unlike other studies exploring the effects of heat release on turbulence, the turbulence is not forced, and detailed chemical kinetics are used to describe hydrogen-air combustion. Budgets for second-order statistics are computed conditioned on progress variable in the premixed flame and on mixture fraction in the nonpremixed flame in order to locate regions with respect to the flame structure where dilatation effects are strongest.
Adaptive Equalizer Based on Second-Order Cone Programming in Underwater Acoustic Communication
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Yang CHEN
2014-01-01
Full Text Available An improved adaptive equalizer based on the principle of minimum mean square error (MMSE is proposed. This optimization problem which is shown to be convex, is transformed to second-order cone (SOC and solved using the interior point method instead of conventional iterative methods such as least mean squares (LMS or recursive least squares (RLS. To validate its performance a single-carrier system for underwater acoustic communication with digital phase-locked loop and the adaptive fractional spaced equalizers was designed and a lake trial was carried out. According to the results, comparing with traditional equalizers based on LMS and RLS algorithms, the equalizer proposed needs no iterative process and gets rid of the contradiction between convergent rate and precision. Therefore it overcomes the difficulty of parameters setting. Furthermore, the algorithm needs much less training codes to achieve the same equalization performance and improves the communication efficiency.
Sliding Mode Based Self-Tuning PID Controller for Second Order Systems
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Alper BAYRAK
2017-11-01
Full Text Available In this paper, a sliding mode based self-tuning PID controller is proposed for uncertain second order systems. While developing the controller, it is assumed that the system model has a part which contains nonlinear terms similar to PID structure which is a new approach in the literature. The controller and update rules for controller parameters are obtained from Lyapunov stability analysis. The proposed controller with update rule is experienced on an experimental 2-DOF helicopter which is also known as Twin-Rotor Multi-Input Multi-Output System (TRMS. From experiments, it was seen that the PID parameter update rules run satisfactorily and, in parallel with this, the controller achieved the control objective by providing the system track the desired trajectory.
Homotopy Algorithm for Optimal Control Problems with a Second-order State Constraint
International Nuclear Information System (INIS)
Hermant, Audrey
2010-01-01
This paper deals with optimal control problems with a regular second-order state constraint and a scalar control, satisfying the strengthened Legendre-Clebsch condition. We study the stability of structure of stationary points. It is shown that under a uniform strict complementarity assumption, boundary arcs are stable under sufficiently smooth perturbations of the data. On the contrary, nonreducible touch points are not stable under perturbations. We show that under some reasonable conditions, either a boundary arc or a second touch point may appear. Those results allow us to design an homotopy algorithm which automatically detects the structure of the trajectory and initializes the shooting parameters associated with boundary arcs and touch points.
Dynamics of second order rational difference equations with open problems and conjectures
Kulenovic, Mustafa RS
2001-01-01
This self-contained monograph provides systematic, instructive analysis of second-order rational difference equations. After classifying the various types of these equations and introducing some preliminary results, the authors systematically investigate each equation for semicycles, invariant intervals, boundedness, periodicity, and global stability. Of paramount importance in their own right, the results presented also offer prototypes towards the development of the basic theory of the global behavior of solutions of nonlinear difference equations of order greater than one. The techniques and results in this monograph are also extremely useful in analyzing the equations in the mathematical models of various biological systems and other applications. Each chapter contains a section of open problems and conjectures that will stimulate further research interest in working towards a complete understanding of the dynamics of the equation and its functional generalizations-many of them ideal for research project...
Burattini, E; Gambicorti, L; Malvezzi, F; Marcelli, A; Monti, F; Pace, E
2005-01-01
This development is the latest result of the cooperation between the National Laboratories of Frascati and the Department of Astronomy and Space Science of the University of Florence to improve the capabilities of the existing DXR-2 beam line at the DAΦNE-LIGHT laboratories. This collaboration has assessed a new facility in order to characterize optics and sensors in a wide spectral range (ranging from VUV to IR). Previous measurements [1] have highlighted some limitations in the present setup, as higher signal levels due to the diffracted radiation of the grating in the second order have to be removed to allow an accurate detection. In this work a glass filter is used to remove such spurious signal present in the spectral region with λ > 360 nm. The characteristics of the filter and its application to the optical system used to measure the sensitivity of a diamond-based photoconductor have been discussed.
Ramses-GPU: Second order MUSCL-Handcock finite volume fluid solver
Kestener, Pierre
2017-10-01
RamsesGPU is a reimplementation of RAMSES (ascl:1011.007) which drops the adaptive mesh refinement (AMR) features to optimize 3D uniform grid algorithms for modern graphics processor units (GPU) to provide an efficient software package for astrophysics applications that do not need AMR features but do require a very large number of integration time steps. RamsesGPU provides an very efficient C++/CUDA/MPI software implementation of a second order MUSCL-Handcock finite volume fluid solver for compressible hydrodynamics as a magnetohydrodynamics solver based on the constraint transport technique. Other useful modules includes static gravity, dissipative terms (viscosity, resistivity), and forcing source term for turbulence studies, and special care was taken to enhance parallel input/output performance by using state-of-the-art libraries such as HDF5 and parallel-netcdf.
Linear reversible second-order cellular automata and their first-order matrix equivalents
Macfarlane, A. J.
2004-11-01
Linear or one-dimensional reversible second-order cellular automata, exemplified by three cases named as RCA1-3, are introduced. Displays of their evolution in discrete time steps, &{\\in}Z_2;) as for RCA1-3. MCA1-3 are tractable because it has been possible to generalize to them the heavy duty methods already well-developed for ordinary first-order cellular automata like those of Wolfram's Rules 90 and 150. While the automata MCA1-3 are thought to be of genuine interest in their own right, with untapped further mathematical potential, their treatment has been applied here to expediting derivation of a large body of general and explicit results for N(t) for RCA1-3. Amongst explicit results obtained are formulas also for each of RCA1-3 for the total weight of the configurations of the first &2^M; times, M =0, 1, 2,\\ldots.
Biondi, Filippo; Ciotti, Piero; Pierdicca, Nazzareno
2013-10-01
In Multi-Baseline SAR tomography it is necessary to process the acquired data by advanced signal processing techniques in order to adequately compensate the bad consequences of an under-sampled configuration. These techniques have to properly work on an environment characterized to have point targets, distributed targets and both of theme. This paper considers the Convex Optimization (CVX) tomographic solution in order to process multi-baseline data-sets collected in a Fourier under-sampled configuration in the above mentioned environment. The CVX and the Second Order Cone Programming Solution (SOCPs) have been tested by a generic log-barrier algorithm, through a successfully computational bottleneck Newton calculation. These techniques are validated on point targets, distributed targets and realistic forested environments.
Taheri, Mehdi; Sheikholeslam, Farid; Najafi, Majddedin; Zekri, Maryam
2017-07-01
In this paper, consensus problem is considered for second order multi-agent systems with unknown nonlinear dynamics under undirected graphs. A novel distributed control strategy is suggested for leaderless systems based on adaptive fuzzy wavelet networks. Adaptive fuzzy wavelet networks are employed to compensate for the effect of unknown nonlinear dynamics. Moreover, the proposed method is developed for leader following systems and leader following systems with state time delays. Lyapunov functions are applied to prove uniformly ultimately bounded stability of closed loop systems and to obtain adaptive laws. Three simulation examples are presented to illustrate the effectiveness of the proposed control algorithms. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Nonsingular Terminal Sliding Mode Control of Uncertain Second-Order Nonlinear Systems
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Minh-Duc Tran
2015-01-01
Full Text Available This paper presents a high-performance nonsingular terminal sliding mode control method for uncertain second-order nonlinear systems. First, a nonsingular terminal sliding mode surface is introduced to eliminate the singularity problem that exists in conventional terminal sliding mode control. By using this method, the system not only can guarantee that the tracking errors reach the reference value in a finite time with high-precision tracking performance but also can overcome the complex-value and the restrictions of the exponent (the exponent should be fractional number with an odd numerator and an odd denominator in traditional terminal sliding mode. Then, in order to eliminate the chattering phenomenon, a super-twisting higher-order nonsingular terminal sliding mode control method is proposed. The stability of the closed-loop system is established using the Lyapunov theory. Finally, simulation results are presented to illustrate the effectiveness of the proposed method.
Second-Order Polynomial Equation-Based Block Adjustment for Orthorectification of DISP Imagery
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Guoqing Zhou
2016-08-01
Full Text Available Due to the lack of ground control points (GCPs and parameters of satellite orbits, as well as the interior and exterior orientation parameters of cameras in historical declassified intelligence satellite photography (DISP imagery, a second order polynomial equation-based block adjustment model is proposed for orthorectification of DISP imagery. With the proposed model, 355 DISP images from four missions and five orbits are orthorectified, with an approximate accuracy of 2.0–3.0 m. The 355 orthorectified images are assembled into a seamless, full-coverage mosaic image map of the karst area of Guangxi, China. The accuracy of the mosaicked image map is within 2.0–4.0 m when compared to 78 checkpoints measured by Real–Time Kinematic (RTK GPS surveys. The assembled image map will be delivered to the Guangxi Geological Library and released to the public domain and the research community.
Sound dispersion in a spin-1 Ising system near the second-order phase transition point
International Nuclear Information System (INIS)
Erdem, Ryza; Keskin, Mustafa
2003-01-01
Sound dispersion relation is derived for a spin-1 Ising system and its behaviour near the second-order phase transition point or the critical point is analyzed. The method used is a combination of molecular field approximation and Onsager theory of irreversible thermodynamics. If we assume a linear coupling of sound wave with the order parameter fluctuations in the system, we find that the dispersion which is the relative sound velocity change with frequency behaves as ω 0 ε 0 , where ω is the sound frequency and ε the temperature distance from the critical point. In the ordered region, one also observes a frequency-dependent velocity or dispersion minimum which is shifted from the corresponding attenuation maxima. These phenomena are in good agreement with the calculations of sound velocity in other magnetic systems such as magnetic metals, magnetic insulators, and magnetic semiconductors
Second-order QCD effects in Higgs boson production through vector boson fusion arXiv
Cruz-Martinez, J.; Glover, E.W.N.; Huss, A.
We compute the factorising second-order QCD corrections to the electroweak production of a Higgs boson through vector boson fusion. Our calculation is fully differential in the kinematics of the Higgs boson and of the final state jets, and uses the antenna subtraction method to handle infrared singular configurations in the different parton-level contributions. Our results allow us to reassess the impact of the next-to-leading order (NLO) QCD corrections to electroweak Higgs-plus-three-jet production and of the next-to-next-to-leading order (NNLO) QCD corrections to electroweak Higgs-plus-two-jet production. The NNLO corrections are found to be limited in magnitude to around $\\pm 5\\%$ and are uniform in several of the kinematical variables, displaying a kinematical dependence only in the transverse momenta and rapidity separation of the two tagging jets.
Presolving and regularization in mixed-integer second-order cone optimization
DEFF Research Database (Denmark)
Friberg, Henrik Alsing
Mixed-integer second-order cone optimization is a powerful mathematical framework capable of representing both logical conditions and nonlinear relationships in mathematical models of industrial optimization problems. What is more, solution methods are already part of many major commercial solvers...... both continuous and mixed-integer conic optimization in general, is discovered and treated. This part of the thesis continues the studies of facial reduction preceding the work of Borwein and Wolkowicz [17] in 1981, when the first algorithmic cure for these kinds of reliability issues were formulated....... An important distinction to make between continuous and mixed-integer optimization, however, is that the reliability issues occurring in mixed-integer optimization cannot be blamed on the practitioner’s formulation of the problem. Specifically, as shown, the causes for these issues may well lie within...
SECOND-ORDER VARIATIONAL ANALYSIS IN CONIC PROGRAMMING WITH APPLICATIONS TO OPTIMALITY AND STABILITY
Czech Academy of Sciences Publication Activity Database
Mordukhovich, B. S.; Outrata, Jiří; Ramírez, H. C.
2015-01-01
Roč. 25, č. 1 (2015), s. 76-101 ISSN 1052-6234 R&D Projects: GA ČR(CZ) GAP201/12/0671 Grant - others:Australian Research Council(AU) DP-110102011; USA National Science Foundation(US) DMS-1007132; Australian Reseach Council(AU) DP-12092508; Portuguese Foundation of Science and Technologies(PT) MAT/11109; FONDECYT Project(CL) 1110888; Universidad de Chile (CL) BASAL Project Centro de Modelamiento Matematico Institutional support: RVO:67985556 Keywords : variational analysis * second-order theory * conic programming * generalized differentiation * optimality conditions * isolated calmness * tilt stability Subject RIV: BA - General Mathematics Impact factor: 2.659, year: 2015 http://library.utia.cas.cz/separaty/2015/MTR/outrata-0439413.pdf
Relaxation approximations to second-order traffic flow models by high-resolution schemes
International Nuclear Information System (INIS)
Nikolos, I.K.; Delis, A.I.; Papageorgiou, M.
2015-01-01
A relaxation-type approximation of second-order non-equilibrium traffic models, written in conservation or balance law form, is considered. Using the relaxation approximation, the nonlinear equations are transformed to a semi-linear diagonilizable problem with linear characteristic variables and stiff source terms with the attractive feature that neither Riemann solvers nor characteristic decompositions are in need. In particular, it is only necessary to provide the flux and source term functions and an estimate of the characteristic speeds. To discretize the resulting relaxation system, high-resolution reconstructions in space are considered. Emphasis is given on a fifth-order WENO scheme and its performance. The computations reported demonstrate the simplicity and versatility of relaxation schemes as numerical solvers
Second-Order Geometric Sliding Mode Attitude Observer with Application to Quadrotor on a Test Bench
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Honglei An
2013-01-01
Full Text Available A sliding mode observer design framework is proposed based on the Lie group method of numerical integration on manifolds, and a Second-Order Geometric Sliding Mode Attitude Observer (SOGSMAO is designed for angular velocity estimation of quadrotor attitude. The algorithm constructs feedback in the angular velocity space and the space of equivalent Lie algebra of unit quaternion space, respectively. It avoids not only the complexity of constructing feedback in unit quaternion space but also the process of mandatory rescaling which is seen to deteriorate the accuracy of the angular velocity estimates during sliding. The performance of SOGSMAO is compared with traditional quaternion based sliding mode observer in which multiplicative quaternion correction is used and the results show that SOGSMAO gains better tracking performance. Then SOGSMAO is realized on a test bed and the effectiveness of the observer algorithm is verified by experimental studies.
Zhu, Yongning; Wang, Yuting; Hellrung, Jeffrey; Cantarero, Alejandro; Sifakis, Eftychios; Teran, Joseph M.
2012-08-01
We present a cut cell method in R2 for enforcing Dirichlet and Neumann boundary conditions with nearly incompressible linear elastic materials in irregular domains. Virtual nodes on cut uniform grid cells are used to provide geometric flexibility in the domain boundary shape without sacrificing accuracy. We use a mixed formulation utilizing a MAC-type staggered grid with piecewise bilinear displacements centered at cell faces and piecewise constant pressures at cell centers. These discretization choices provide the necessary stability in the incompressible limit and the necessary accuracy in cut cells. Numerical experiments suggest second order accuracy in L∞. We target high-resolution problems and present a class of geometric multigrid methods for solving the discrete equations for displacements and pressures that achieves nearly optimal convergence rates independent of grid resolution.
Invariants of a family of scalar second-order ordinary differential equations
International Nuclear Information System (INIS)
Bagderina, Yulia Yu
2013-01-01
The family of second-order equations with cubic nonlinearity in the first-order derivative is closed with respect to an arbitrary point change of variables. Algebraic and differential invariants for these equations which depend on the first-order derivatives are considered. We solve completely the equivalence problem for this family of equations in the generic case and also for degenerate types of these equations. Fifty equations having the Painlevé property, which have been classified by Painlevé and Gambier, belong to this remarkable family. Algebraic invariants of all these equations are calculated and constant invariants are listed in the paper. Invariant characterization of the fourth Painlevé equation is given. (paper)
Growth and Zeros of Meromorphic Solutions to Second-Order Linear Differential Equations
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Maamar Andasmas
2016-04-01
Full Text Available The main purpose of this article is to investigate the growth of meromorphic solutions to homogeneous and non-homogeneous second order linear differential equations f00+Af0+Bf = F, where A(z, B (z and F (z are meromorphic functions with finite order having only finitely many poles. We show that, if there exist a positive constants σ > 0, α > 0 such that |A(z| ≥ eα|z|σ as |z| → +∞, z ∈ H, where dens{|z| : z ∈ H} > 0 and ρ = max{ρ(B, ρ(F} < σ, then every transcendental meromorphic solution f has an infinite order. Further, we give some estimates of their hyper-order, exponent and hyper-exponent of convergence of distinct zeros.
An optimal PID controller via LQR for standard second order plus time delay systems.
Srivastava, Saurabh; Misra, Anuraag; Thakur, S K; Pandit, V S
2016-01-01
An improved tuning methodology of PID controller for standard second order plus time delay systems (SOPTD) is developed using the approach of Linear Quadratic Regulator (LQR) and pole placement technique to obtain the desired performance measures. The pole placement method together with LQR is ingeniously used for SOPTD systems where the time delay part is handled in the controller output equation instead of characteristic equation. The effectiveness of the proposed methodology has been demonstrated via simulation of stable open loop oscillatory, over damped, critical damped and unstable open loop systems. Results show improved closed loop time response over the existing LQR based PI/PID tuning methods with less control effort. The effect of non-dominant pole on the stability and robustness of the controller has also been discussed. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Daqing Jiang
1998-01-01
Full Text Available We use a fixed point index theorem in cones to study the existence of positive solutions for boundary value problems of second-order functional differential equations of the form $$\\left\\{ \\begin{array}{ll} y''(x+r(xf(y(w(x=0,&0
The Interaction Between Control Rods as Estimated by Second-Order One-Group Perturbation Theory
Energy Technology Data Exchange (ETDEWEB)
Persson, Rolf
1966-10-15
The interaction effect between control rods is an important problem for the reactivity control of a reactor. The approach of second order one-group perturbation theory is shown to be attractive due to its simplicity. Formulas are derived for the fully inserted control rods in a bare reactor. For a single rod we introduce a correction parameter b, which with good approximation is proportional to the strength of the absorber. For two and more rods we introduce an interaction function g(r{sub ij}), which is assumed to depend only on the distance r{sub ij} between the rods. The theoretical expressions are correlated with the results of several experiments in R0, ZEBRA and the Aagesta reactor, as well as with more sophisticated calculations. The approximate formulas are found to give quite good agreement with exact values, but in the case of about 8 or more rods higher-order effects are likely to be important.
First integrals, integrating factors and λ-symmetries of second-order differential equations
International Nuclear Information System (INIS)
Muriel, C; Romero, J L
2009-01-01
For a given second-order ordinary differential equation (ODE), several relationships among first integrals, integrating factors and λ-symmetries are studied. The knowledge of a λ-symmetry of the equation permits the determination of an integrating factor or a first integral by means of coupled first-order linear systems of partial differential equations. If two nonequivalent λ-symmetries of the equation are known, then an algorithm to find two functionally independent first integrals is provided. These methods include and complete other methods to find integrating factors or first integrals that are based on variational derivatives or in the Prelle-Singer method. These results are applied to several ODEs that appear in the study of relevant equations of mathematical physics.
Second-order optical effects in several pyrazolo-quinoline derivatives
Energy Technology Data Exchange (ETDEWEB)
Makowska-Janusik, M. [Solid State Department, Institute of Physics, WSP Czestochowa, Al. Armii Krajowej 13/15, Czestochowa PL42201 (Poland); Gondek, E. [Institute of Physics, Cracow University of Technology, ul. Podchorazych 1, 30-084 (Poland); Kityk, I.V. [Department of Biology and Biophysics, Technical University of Czestochowa, Al. Armii Krajowej 36, Czestochowa PL-42210 (Poland)]. E-mail: i.kityk@wsp.czest.pl; WisIa, J. [Departament of Chemistry, Hugon Kollataj Agricultural University, Al. Mickiewicza 24/28, 30-059 Cracow (Poland); Sanetra, J. [Institute of Physics, Cracow University of Technology, ul. Podchorazych 1, 30-084 (Poland); Danel, A. [Department of Chemistry, Hugon Kollataj Agricultural University, Al. Mickiewicza 24/28, 30-059 Cracow (Poland)
2004-11-15
Using optical poling of several pyazolo-quinoline (PAQ) derivatives we have found an existence of sufficiently high second order optical susceptibility at wavelength 1.76 {mu}m varying in the range 0.9-2.8 pm/V. The performed quantum chemical simulations of the UV-absorption for isolated, solvated and incorporated into the polymethacrylate (PMMA) polymer films have shown that the PM3 method is the best among the semi-empirical ones to simulate the optical properties. The calculations of the hyperpolarizabilites have shown a good correlation with experimentally measured susceptibilities obtained from the optical poling. We have found that experimental susceptibility depends on linear molecular polarizability and photoinducing changes of the molecular dipole moment. It is clearly seen for the PAQ4-PAQ6 molecules possessing halogen atoms with relatively large polarizabilities.
Second-order optical effects in several pyrazolo-quinoline derivatives
International Nuclear Information System (INIS)
Makowska-Janusik, M.; Gondek, E.; Kityk, I.V.; WisIa, J.; Sanetra, J.; Danel, A.
2004-01-01
Using optical poling of several pyazolo-quinoline (PAQ) derivatives we have found an existence of sufficiently high second order optical susceptibility at wavelength 1.76 μm varying in the range 0.9-2.8 pm/V. The performed quantum chemical simulations of the UV-absorption for isolated, solvated and incorporated into the polymethacrylate (PMMA) polymer films have shown that the PM3 method is the best among the semi-empirical ones to simulate the optical properties. The calculations of the hyperpolarizabilites have shown a good correlation with experimentally measured susceptibilities obtained from the optical poling. We have found that experimental susceptibility depends on linear molecular polarizability and photoinducing changes of the molecular dipole moment. It is clearly seen for the PAQ4-PAQ6 molecules possessing halogen atoms with relatively large polarizabilities
Second-order optical effects in several pyrazolo-quinoline derivatives
Makowska-Janusik, M.; Gondek, E.; Kityk, I. V.; Wisła, J.; Sanetra, J.; Danel, A.
2004-11-01
Using optical poling of several pyazolo-quinoline (PAQ) derivatives we have found an existence of sufficiently high second order optical susceptibility at wavelength 1.76 μm varying in the range 0.9-2.8 pm/V. The performed quantum chemical simulations of the UV-absorption for isolated, solvated and incorporated into the polymethacrylate (PMMA) polymer films have shown that the PM3 method is the best among the semi-empirical ones to simulate the optical properties. The calculations of the hyperpolarizabilites have shown a good correlation with experimentally measured susceptibilities obtained from the optical poling. We have found that experimental susceptibility depends on linear molecular polarizability and photoinducing changes of the molecular dipole moment. It is clearly seen for the PAQ4-PAQ6 molecules possessing halogen atoms with relatively large polarizabilities.
The structure of the second-order non-Born-Oppenheimer density matriz D2:
Ludena, Eduardo; Iza, Peter; Aray, Yosslen; Cornejo, Mauricio; Zambrano, Dik
Properties of the non-Born-Oppenheimer 2-matrix are examined. Using a coordinate system formed by internal translationally invariant plus the total center-of-mass coordinates it is shown that regardless of the point of reference selected, the operator for the reduced second order density matrix, 2-RDM, solely depends upon the translationally invariant internal coordinates. We apply this result to examine the nature of the 2-RDM extracted from the exact analytical solutions for model non-Born-Oppenheimer four-particle systems of the Coulomb-Hooke and Moshinsky types. We obtain for both these models explicit closed-form analytic expressions for the electron and nuclear 2-RDM. An explicit expression is also obtained for the electron-nuclear 2-RDM in the Moshinsky case, which shows coupling between the electron and nuclear coordinates. EVL and YA acknowledge support of SENESCYT's Prometheus Program.
Relaxation approximations to second-order traffic flow models by high-resolution schemes
Energy Technology Data Exchange (ETDEWEB)
Nikolos, I.K.; Delis, A.I.; Papageorgiou, M. [School of Production Engineering and Management, Technical University of Crete, University Campus, Chania 73100, Crete (Greece)
2015-03-10
A relaxation-type approximation of second-order non-equilibrium traffic models, written in conservation or balance law form, is considered. Using the relaxation approximation, the nonlinear equations are transformed to a semi-linear diagonilizable problem with linear characteristic variables and stiff source terms with the attractive feature that neither Riemann solvers nor characteristic decompositions are in need. In particular, it is only necessary to provide the flux and source term functions and an estimate of the characteristic speeds. To discretize the resulting relaxation system, high-resolution reconstructions in space are considered. Emphasis is given on a fifth-order WENO scheme and its performance. The computations reported demonstrate the simplicity and versatility of relaxation schemes as numerical solvers.
The Interaction Between Control Rods as Estimated by Second-Order One-Group Perturbation Theory
International Nuclear Information System (INIS)
Persson, Rolf
1966-10-01
The interaction effect between control rods is an important problem for the reactivity control of a reactor. The approach of second order one-group perturbation theory is shown to be attractive due to its simplicity. Formulas are derived for the fully inserted control rods in a bare reactor. For a single rod we introduce a correction parameter b, which with good approximation is proportional to the strength of the absorber. For two and more rods we introduce an interaction function g(r ij ), which is assumed to depend only on the distance r ij between the rods. The theoretical expressions are correlated with the results of several experiments in R0, ZEBRA and the Aagesta reactor, as well as with more sophisticated calculations. The approximate formulas are found to give quite good agreement with exact values, but in the case of about 8 or more rods higher-order effects are likely to be important
Dynamics of Equilibrium Points in a Uniformly Rotating Second-Order and Degree Gravitational Field
Feng, Jinglang; Hou, Xiyun
2017-07-01
Using tools such as periodic orbits and invariant manifolds, the global dynamics around equilibrium points (EPs) in a rotating second-order and degree gravitational field are studied. For EPs on the long axis, planar and vertical periodic families are computed, and their stability properties are investigated. Invariant manifolds are also computed, and their relation to the first-order resonances is briefly discussed. For EPs on the short axis, planar and vertical periodic families are studied, with special emphasis on the genealogy of the planar periodic families. Our studies show that the global dynamics around EPs are highly similar to those around libration points in the circular restricted three-body problem, such as spatial halo orbits, invariant manifolds, and the genealogy of planar periodic families.
Directory of Open Access Journals (Sweden)
Zhonghai Guo
2012-01-01
Full Text Available We study the following second order mixed nonlinear impulsive differential equations with delay (r(tΦα(x′(t′+p0(tΦα(x(t+∑i=1npi(tΦβi(x(t-σ=e(t, t≥t0, t≠τk,x(τk+=akx(τk, x'(τk+=bkx'(τk, k=1,2,…, where Φ*(u=|u|*-1u, σ is a nonnegative constant, {τk} denotes the impulsive moments sequence, and τk+1-τk>σ. Some sufficient conditions for the interval oscillation criteria of the equations are obtained. The results obtained generalize and improve earlier ones. Two examples are considered to illustrate the main results.
Extended observer based on adaptive second order sliding mode control for a fixed wing UAV.
Castañeda, Herman; Salas-Peña, Oscar S; León-Morales, Jesús de
2017-01-01
This paper addresses the design of attitude and airspeed controllers for a fixed wing unmanned aerial vehicle. An adaptive second order sliding mode control is proposed for improving performance under different operating conditions and is robust in presence of external disturbances. Moreover, this control does not require the knowledge of disturbance bounds and avoids overestimation of the control gains. Furthermore, in order to implement this controller, an extended observer is designed to estimate unmeasurable states as well as external disturbances. Additionally, sufficient conditions are given to guarantee the closed-loop stability of the observer based control. Finally, using a full 6 degree of freedom model, simulation results are obtained where the performance of the proposed method is compared against active disturbance rejection based on sliding mode control. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
Optimal tracking and second order sliding power control of the DFIG wind turbine
Abdeddaim, S.; Betka, A.; Charrouf, O.
2017-02-01
In the present paper, an optimal operation of a grid-connected variable speed wind turbine equipped with a Doubly Fed Induction Generator (DFIG) is presented. The proposed cascaded nonlinear controller is designed to perform two main objectives. In the outer loop, a maximum power point tracking (MPPT) algorithm based on fuzzy logic theory is designed to permanently extract the optimal aerodynamic energy, whereas in the inner loop, a second order sliding mode control (2-SM) is applied to achieve smooth regulation of both stator active and reactive powers quantities. The obtained simulation results show a permanent track of the MPP point regardless of the turbine power-speed slope moreover the proposed sliding mode control strategy presents attractive features such as chattering-free, compared to the conventional first order sliding technique (1-SM).
A Separation Algorithm for Sources with Temporal Structure Only Using Second-order Statistics
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J.G. Wang
2013-09-01
Full Text Available Unlike conventional blind source separation (BSS deals with independent identically distributed (i.i.d. sources, this paper addresses the separation from mixtures of sources with temporal structure, such as linear autocorrelations. Many sequential extraction algorithms have been reported, resulting in inevitable cumulated errors introduced by the deflation scheme. We propose a robust separation algorithm to recover original sources simultaneously, through a joint diagonalizer of several average delayed covariance matrices at positions of the optimal time delay and its integers. The proposed algorithm is computationally simple and efficient, since it is based on the second-order statistics only. Extensive simulation results confirm the validity and high performance of the algorithm. Compared with related extraction algorithms, its separation signal-to-noise rate for a desired source can reach 20dB higher, and it seems rather insensitive to the estimation error of the time delay.
Oscillation criteria for second order Emden-Fowler functional differential equations of neutral type
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Yingzhu Wu
2016-12-01
Full Text Available Abstract In this article, some new oscillation criterion for the second order Emden-Fowler functional differential equation of neutral type ( r ( t | z ′ ( t | α − 1 z ′ ( t ′ + q ( t | x ( σ ( t | β − 1 x ( σ ( t = 0 , $$\\bigl(r(t\\bigl\\vert z^{\\prime}(t\\bigr\\vert ^{\\alpha-1}z^{\\prime}(t \\bigr^{\\prime}+q(t\\bigl\\vert x\\bigl(\\sigma(t\\bigr\\bigr\\vert ^{\\beta-1}x \\bigl(\\sigma(t \\bigr=0, $$ where z ( t = x ( t + p ( t x ( τ ( t $z(t=x(t+p(tx(\\tau(t$ , α > 0 $\\alpha>0$ and β > 0 $\\beta>0$ are established. Our results improve some well-known results which were published recently in the literature. Some illustrating examples are also provided to show the importance of our results.
International Nuclear Information System (INIS)
Valone, S.M.; Truhlar, D.G.; Thirumialai, D.
1982-01-01
A local approximation to the second-order optical potential for elastic scattering of low-energy electrons from ground-state atoms is expressed in terms of the imaginary-frequency susceptibilities of the atom due to a point charge and to modified perturbing potentials. This provides a basis for the physically appealing concept of regarding the perturbation due to the projectile as having a position-dependent effective frequency associated with it. The result is extended to higher energies with the use of the concept of a local kinetic energy. With a semiclassical approximation the result reduces to a simple general form that should be useful for model potential studies of electron-atom and electron-molecule scattering. Alternatively, variational functionals for the susceptibilities can be used to calculate the approximate optical potential most rigorously without making effective-frequency, average-kinetic-energy, or semiclassical approximations. Intermediate levels of rigor are also possible
Gravitational effective action at second order in curvature and gravitational waves.
Calmet, Xavier; Capozziello, Salvatore; Pryer, Daniel
2017-01-01
We consider the full effective theory for quantum gravity at second order in curvature including non-local terms. We show that the theory contains two new degrees of freedom beyond the massless graviton: namely a massive spin-2 ghost and a massive scalar field. Furthermore, we show that it is impossible to fine-tune the parameters of the effective action to eliminate completely the classical spin-2 ghost because of the non-local terms in the effective action. Being a classical field, it is not clear anyway that this ghost is problematic. It simply implies a repulsive contribution to Newton's potential. We then consider how to extract the parameters of the effective action and show that it is possible to measure, at least in principle, the parameters of the local terms independently of each other using a combination of observations of gravitational waves and measurements performed by pendulum type experiments searching for deviations of Newton's potential.
Zhou, Yun; Pollak, Eli; Miret-Artés, Salvador
2014-01-14
A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to "soft" corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.
An approach for second order control with finite time convergence for electro-hydraulic drives
DEFF Research Database (Denmark)
Schmidt, Lasse; Andersen, Torben Ole; Pedersen, Henrik C.
2013-01-01
algorithm parameters. However a discontinuous term internally in the control structure may excite pressures of transmission lines in hydraulic drives as the control structure strives to maintain the control error and its derivative equal to zero. In this paper a modified version of a controller based......Being a second order sliding algorithm, the super twisting algorithm is highly attractive for application in control of hydraulic drives and mechanical systems in general, as it utilizes only the control error while driving the control error as well as its derivative to zero for properly chosen...... on the super twisting algorithm is proposed, with the focus of eliminating the discontinuous term in order to achieve a more smooth control operation. The convergence properties of the proposed controller are analyzed via a conservative phase plane analysis. Furthermore, homogeneity considerations imply finite...
Second-Order Chaos Indicators MEGNO2 and OMEGNO2: Theory
Shefer, V. A.
2018-02-01
Modifications of the Mean Exponential Growth factor of Nearby Orbits (MEGNO) linear variational method called MEGNO2 and OMEGNO2 indicators are introduced. The modifications are based on taking into account not only the linear, but also the nonlinear part of the increment of the phase flow in the divergence among nearby trajectories according to the second-order formulas. The new indicators allow one to determine more quickly the nature of the orbits under study in dynamical systems with zero or small Lyapunov exponents in comparison with the first-order variational indicators. They improve the analysis of regular regions and, in particular, periodic orbits as well as prevent the appearance of spurious structures in the resulting mappings.
Dynamics of Equilibrium Points in a Uniformly Rotating Second-Order and Degree Gravitational Field
Energy Technology Data Exchange (ETDEWEB)
Feng, Jinglang; Hou, Xiyun, E-mail: jinglang@nju.edu.cn, E-mail: silence@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, 210093 (China)
2017-07-01
Using tools such as periodic orbits and invariant manifolds, the global dynamics around equilibrium points (EPs) in a rotating second-order and degree gravitational field are studied. For EPs on the long axis, planar and vertical periodic families are computed, and their stability properties are investigated. Invariant manifolds are also computed, and their relation to the first-order resonances is briefly discussed. For EPs on the short axis, planar and vertical periodic families are studied, with special emphasis on the genealogy of the planar periodic families. Our studies show that the global dynamics around EPs are highly similar to those around libration points in the circular restricted three-body problem, such as spatial halo orbits, invariant manifolds, and the genealogy of planar periodic families.
Stochastic evaluation of second-order many-body perturbation energies
Willow, Soohaeng Yoo; Kim, Kwang S.; Hirata, So
2012-11-01
With the aid of the Laplace transform, the canonical expression of the second-order many-body perturbation correction to an electronic energy is converted into the sum of two 13-dimensional integrals, the 12-dimensional parts of which are evaluated by Monte Carlo integration. Weight functions are identified that are analytically normalizable, are finite and non-negative everywhere, and share the same singularities as the integrands. They thus generate appropriate distributions of four-electron walkers via the Metropolis algorithm, yielding correlation energies of small molecules within a few mEh of the correct values after 108 Monte Carlo steps. This algorithm does away with the integral transformation as the hotspot of the usual algorithms, has a far superior size dependence of cost, does not suffer from the sign problem of some quantum Monte Carlo methods, and potentially easily parallelizable and extensible to other more complex electron-correlation theories.
Fang, Hao; Wei, Yue; Chen, Jie; Xin, Bin
2017-04-01
The problem of flocking of second-order multiagent systems with connectivity preservation is investigated in this paper. First, for estimating the algebraic connectivity as well as the corresponding eigenvector, a new decentralized inverse power iteration scheme is formulated. Then, based on the estimation of the algebraic connectivity, a set of distributed gradient-based flocking control protocols is built with a new class of generalized hybrid potential fields which could guarantee collision avoidance, desired distance stabilization, and the connectivity of the underlying communication network simultaneously. What is important is that the proposed control scheme allows the existing edges to be broken without violation of connectivity constraints, and thus yields more flexibility of motions and reduces the communication cost for the multiagent system. In the end, nontrivial comparative simulations and experimental results are performed to demonstrate the effectiveness of the theoretical results and highlight the advantages of the proposed estimation scheme and control algorithm.
Quantized flocking control for second-order multiple agents with obstacle avoidance
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Chunguang Li
2016-01-01
Full Text Available A quantized flocking control for a group of second-order multiple agents with obstacle avoidance is proposed to address the problem of the exchange of information needed for quantification. With a reasonable assumption, a logarithmic or uniform quantizer is used for the exchange of relative position and velocity information between adjacent agents and the virtual leader, moving at a steady speed along a straight line, and a distributed flocking algorithm with obstacle avoidance capability is designed based on the quantitative information. The Lyapunov stability criterion of nonsmooth systems and the invariance principle are used to prove the stability of these systems. The simulations and experiments are presented to demonstrate the feasibility and effectiveness of the proposed approach.
Jain, Anoop; Ghose, Debasish
2018-01-01
This paper considers collective circular motion of multi-agent systems in which all the agents are required to traverse different circles or a common circle at a prescribed angular velocity. It is required to achieve these collective motions with the heading angles of the agents synchronized or balanced. In synchronization, the agents and their centroid have a common velocity direction, while in balancing, the movement of agents causes the location of the centroid to become stationary. The agents are initially considered to move at unit speed around individual circles at different angular velocities. It is assumed that the agents are subjected to limited communication constraints, and exchange relative information according to a time-invariant undirected graph. We present suitable feedback control laws for each of these motion coordination tasks by considering a second-order rotational dynamics of the agent. Simulations are given to illustrate the theoretical findings.
Second-Order Statistics for Wave Propagation through Complex Optical Systems
DEFF Research Database (Denmark)
Yura, H.T.; Hanson, Steen Grüner
1989-01-01
Closed-form expressions are derived for various statistical functions that arise in optical propagation through arbitrary optical systems that can be characterized by a complex ABCD matrix in the presence of distributed random inhomogeneities along the optical path. Specifically, within the second......-order Rytov approximation, explicit general expressions are presented for the mutual coherence function, the log-amplitude and phase correlation functions, and the mean-square irradiance that are obtained in propagation through an arbitrary paraxial ABCD optical system containing Gaussian-shaped limiting...... apertures. Additionally, we consider the performance of adaptive-optics systems through arbitrary real paraxial ABCD optical systems and derive an expression for the mean irradiance of an adaptive-optics laser transmitter through such systems. © 1989 Optical Society of America...
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Dimal A. Shah
2017-02-01
Full Text Available A simple and accurate method for the analysis of ibuprofen (IBU and famotidine (FAM in their combined dosage form was developed using second order derivative spectrophotometery. IBU and FAM were quantified using second derivative responses at 272.8 nm and 290 nm in the spectra of their solutions in methanol. The calibration curves were linear in the concentration range of 100–600 μg/mL for IBU and 5–25 μg/mL for FAM. The method was validated and found to be accurate and precise. Developed method was successfully applied for the estimation of IBU and FAM in their combined dosage form.
Arslan, Burcu; Hohenberger, Annette; Verbrugge, Rineke
2012-01-01
In this study, the development of second-order social cognition and its possible relationship with language and memory were investigated. For this reason two second-order false belief tasks (FBT_2), a short term memory task (WST), a complex working memory task (LST), a linguistic perspective-taking
Borghesani, P.; Pennacchi, P.; Ricci, R.; Chatterton, S.
2013-10-01
Cyclostationary models for the diagnostic signals measured on faulty rotating machineries have proved to be successful in many laboratory tests and industrial applications. The squared envelope spectrum has been pointed out as the most efficient indicator for the assessment of second order cyclostationary symptoms of damages, which are typical, for instance, of rolling element bearing faults. In an attempt to foster the spread of rotating machinery diagnostics, the current trend in the field is to reach higher levels of automation of the condition monitoring systems. For this purpose, statistical tests for the presence of cyclostationarity have been proposed during the last years. The statistical thresholds proposed in the past for the identification of cyclostationary components have been obtained under the hypothesis of having a white noise signal when the component is healthy. This need, coupled with the non-white nature of the real signals implies the necessity of pre-whitening or filtering the signal in optimal narrow-bands, increasing the complexity of the algorithm and the risk of losing diagnostic information or introducing biases on the result. In this paper, the authors introduce an original analytical derivation of the statistical tests for cyclostationarity in the squared envelope spectrum, dropping the hypothesis of white noise from the beginning. The effect of first order and second order cyclostationary components on the distribution of the squared envelope spectrum will be quantified and the effectiveness of the newly proposed threshold verified, providing a sound theoretical basis and a practical starting point for efficient automated diagnostics of machine components such as rolling element bearings. The analytical results will be verified by means of numerical simulations and by using experimental vibration data of rolling element bearings.
Pfanzelt, Sandra; Rössert, Christian; Rohregger, Martin; Glasauer, Stefan; Moore, Lee E; Straka, Hans
2008-10-08
The sensory-motor transformation of the large dynamic spectrum of head-motion-related signals occurs in separate vestibulo-ocular pathways. Synaptic responses of tonic and phasic second-order vestibular neurons were recorded in isolated frog brains after stimulation of individual labyrinthine nerve branches with trains of single electrical pulses. The timing of the single pulses was adapted from spike discharge patterns of frog semicircular canal nerve afferents during sinusoidal head rotation. Because each electrical pulse evoked a single spike in afferent fibers, the resulting sequences with sinusoidally modulated intervals and peak frequencies up to 100 Hz allowed studying the processing of presynaptic afferent inputs with in vivo characteristics in second-order vestibular neurons recorded in vitro in an isolated whole brain. Variation of pulse-train parameters showed that the postsynaptic compound response dynamics differ in the two types of frog vestibular neurons. In tonic neurons, subthreshold compound responses and evoked discharge patterns exhibited relatively linear dynamics and were generally aligned with pulse frequency modulation. In contrast, compound responses of phasic neurons were asymmetric with large leads of subthreshold response peaks and evoked spike discharge relative to stimulus waveform. These nonlinearities were caused by the particular intrinsic properties of phasic vestibular neurons and were facilitated by GABAergic and glycinergic inhibitory inputs from tonic type vestibular interneurons and by cerebellar circuits. Coadapted intrinsic filter and emerging network properties thus form dynamically different neuronal elements that provide the appropriate cellular basis for a parallel processing of linear, tonic, and nonlinear phasic vestibulo-ocular response components in central vestibular neurons.
Consistent second-order boundary implementations for convection-diffusion lattice Boltzmann method
Zhang, Liangqi; Yang, Shiliang; Zeng, Zhong; Chew, Jia Wei
2018-02-01
In this study, an alternative second-order boundary scheme is proposed under the framework of the convection-diffusion lattice Boltzmann (LB) method for both straight and curved geometries. With the proposed scheme, boundary implementations are developed for the Dirichlet, Neumann and linear Robin conditions in a consistent way. The Chapman-Enskog analysis and the Hermite polynomial expansion technique are first applied to derive the explicit expression for the general distribution function with second-order accuracy. Then, the macroscopic variables involved in the expression for the distribution function is determined by the prescribed macroscopic constraints and the known distribution functions after streaming [see the paragraph after Eq. (29) for the discussions of the "streaming step" in LB method]. After that, the unknown distribution functions are obtained from the derived macroscopic information at the boundary nodes. For straight boundaries, boundary nodes are directly placed at the physical boundary surface, and the present scheme is applied directly. When extending the present scheme to curved geometries, a local curvilinear coordinate system and first-order Taylor expansion are introduced to relate the macroscopic variables at the boundary nodes to the physical constraints at the curved boundary surface. In essence, the unknown distribution functions at the boundary node are derived from the known distribution functions at the same node in accordance with the macroscopic boundary conditions at the surface. Therefore, the advantages of the present boundary implementations are (i) the locality, i.e., no information from neighboring fluid nodes is required; (ii) the consistency, i.e., the physical boundary constraints are directly applied when determining the macroscopic variables at the boundary nodes, thus the three kinds of conditions are realized in a consistent way. It should be noted that the present focus is on two-dimensional cases, and theoretical
A second-order accurate immersed boundary-lattice Boltzmann method for particle-laden flows
Energy Technology Data Exchange (ETDEWEB)
Zhou, Qiang; Fan, Liang-Shih, E-mail: fan.1@osu.edu
2014-07-01
A new immersed boundary-lattice Boltzmann method (IB-LBM) is presented for fully resolved simulations of incompressible viscous flows laden with rigid particles. The immersed boundary method (IBM) recently developed by Breugem (2012) [19] is adopted in the present method, development including the retraction technique, the multi-direct forcing method and the direct account of the inertia of the fluid contained within the particles. The present IB-LBM is, however, formulated with further improvement with the implementation of the high-order Runge–Kutta schemes in the coupled fluid–particle interaction. The major challenge to implement high-order Runge–Kutta schemes in the LBM is that the flow information such as density and velocity cannot be directly obtained at a fractional time step from the LBM since the LBM only provides the flow information at an integer time step. This challenge can be, however, overcome as given in the present IB-LBM by extrapolating the flow field around particles from the known flow field at the previous integer time step. The newly calculated fluid–particle interactions from the previous fractional time steps of the current integer time step are also accounted for in the extrapolation. The IB-LBM with high-order Runge–Kutta schemes developed in this study is validated by several benchmark applications. It is demonstrated, for the first time, that the IB-LBM has the capacity to resolve the translational and rotational motion of particles with the second-order accuracy. The optimal retraction distances for spheres and tubes that help the method achieve the second-order accuracy are found to be around 0.30 and −0.47 times of the lattice spacing, respectively. Simulations of the Stokes flow through a simple cubic lattice of rotational spheres indicate that the lift force produced by the Magnus effect can be very significant in view of the magnitude of the drag force when the practical rotating speed of the spheres is encountered
A second-order accurate immersed boundary-lattice Boltzmann method for particle-laden flows
Zhou, Qiang; Fan, Liang-Shih
2014-07-01
A new immersed boundary-lattice Boltzmann method (IB-LBM) is presented for fully resolved simulations of incompressible viscous flows laden with rigid particles. The immersed boundary method (IBM) recently developed by Breugem (2012) [19] is adopted in the present method, development including the retraction technique, the multi-direct forcing method and the direct account of the inertia of the fluid contained within the particles. The present IB-LBM is, however, formulated with further improvement with the implementation of the high-order Runge-Kutta schemes in the coupled fluid-particle interaction. The major challenge to implement high-order Runge-Kutta schemes in the LBM is that the flow information such as density and velocity cannot be directly obtained at a fractional time step from the LBM since the LBM only provides the flow information at an integer time step. This challenge can be, however, overcome as given in the present IB-LBM by extrapolating the flow field around particles from the known flow field at the previous integer time step. The newly calculated fluid-particle interactions from the previous fractional time steps of the current integer time step are also accounted for in the extrapolation. The IB-LBM with high-order Runge-Kutta schemes developed in this study is validated by several benchmark applications. It is demonstrated, for the first time, that the IB-LBM has the capacity to resolve the translational and rotational motion of particles with the second-order accuracy. The optimal retraction distances for spheres and tubes that help the method achieve the second-order accuracy are found to be around 0.30 and -0.47 times of the lattice spacing, respectively. Simulations of the Stokes flow through a simple cubic lattice of rotational spheres indicate that the lift force produced by the Magnus effect can be very significant in view of the magnitude of the drag force when the practical rotating speed of the spheres is encountered. This finding
Apparao, Siddangouda; Biradar, Trimbak Vaijanath; Naduvinamani, Neminath Bhujappa
2014-01-01
Theoretical study of non-Newtonian effects of second-order fluids on the performance characteristics of inclined slider bearings is presented. An approximate method is used for the solution of the highly nonlinear momentum equations for the second-order fluids. The closed form expressions for the fluid film pressure, load carrying capacity, frictional force, coefficient of friction, and centre of pressure are obtained. The non-Newtonian second order fluid model increases the film pressure, load carrying capacity, and frictional force whereas the center of pressure slightly shifts towards exit region. Further, the frictional coefficient decreases with an increase in the bearing velocity as expected for an ideal fluid.
A survey on orthogonal matrix polynomials satisfying second order differential equations
Duran, Antonio J.; Grunbaum, F. Alberto
2005-06-01
The subject of orthogonal polynomials cuts across a large piece of mathematics and its applications. Two notable examples are mathematical physics in the 19th and 20th centuries, as well as the theory of spherical functions for symmetric spaces. It is also clear that many areas of mathematics grew out of the consideration of problems like the moment problem that are intimately associated to the study of (scalar valued) orthogonal polynomials.Matrix orthogonality on the real line has been sporadically studied during the last half century since Krein devoted some papers to the subject in 1949, see (AMS Translations, Series 2, vol. 97, Providence, Rhode Island, 1971, pp. 75-143, Dokl. Akad. Nauk SSSR 69(2) (1949) 125). In the last decade this study has been made more systematic with the consequence that many basic results of scalar orthogonality have been extended to the matrix case. The most recent of these results is the discovery of important examples of orthogonal matrix polynomials: many families of orthogonal matrix polynomials have been found that (as the classical families of Hermite, Laguerre and Jacobi in the scalar case) satisfy second order differential equations with coefficients independent of n. The aim of this paper is to give an overview of the techniques that have led to these examples, a small sample of the examples themselves and a small step in the challenging direction of finding applications of these new examples.
Directory of Open Access Journals (Sweden)
Jaroslav Jaroš
2015-01-01
Full Text Available We consider \\(n\\-dimensional cyclic systems of second order differential equations \\[(p_i(t|x_{i}'|^{\\alpha_i -1}x_{i}'' = q_{i}(t|x_{i+1}|^{\\beta_i-1}x_{i+1},\\] \\[\\quad i = 1,\\ldots,n, \\quad (x_{n+1} = x_1 \\tag{\\(\\ast\\}\\] under the assumption that the positive constants \\(\\alpha_i\\ and \\(\\beta_i\\ satisfy \\(\\alpha_1{\\ldots}\\alpha_n \\gt \\beta_1{\\ldots}\\beta_n\\ and \\(p_i(t\\ and \\(q_i(t\\ are regularly varying functions, and analyze positive strongly increasing solutions of system (\\(\\ast\\ in the framework of regular variation. We show that the situation for the existence of regularly varying solutions of positive indices for (\\(\\ast\\ can be characterized completely, and moreover that the asymptotic behavior of such solutions is governed by the unique formula describing their order of growth precisely. We give examples demonstrating that the main results for (\\(\\ast\\ can be applied to some classes of partial differential equations with radial symmetry to acquire accurate information about the existence and the asymptotic behavior of their radial positive strongly increasing solutions.
Gravitational effective action at second order in curvature and gravitational waves
Energy Technology Data Exchange (ETDEWEB)
Calmet, Xavier; Pryer, Daniel [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom); Capozziello, Salvatore [Universita di Napoli ' ' Federico II' ' , Dipartimento di Fisica ' ' E. Pancini' ' , Naples (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Naples (Italy); Gran Sasso Science Institute, L' Aquila (Italy)
2017-09-15
We consider the full effective theory for quantum gravity at second order in curvature including non-local terms. We show that the theory contains two new degrees of freedom beyond the massless graviton: namely a massive spin-2 ghost and a massive scalar field. Furthermore, we show that it is impossible to fine-tune the parameters of the effective action to eliminate completely the classical spin-2 ghost because of the non-local terms in the effective action. Being a classical field, it is not clear anyway that this ghost is problematic. It simply implies a repulsive contribution to Newton's potential. We then consider how to extract the parameters of the effective action and show that it is possible to measure, at least in principle, the parameters of the local terms independently of each other using a combination of observations of gravitational waves and measurements performed by pendulum type experiments searching for deviations of Newton's potential. (orig.)
Fit of second order thermoluminescence glow peaks using the logistic distribution function
International Nuclear Information System (INIS)
Pagonis, V.; Kitis, G.
2001-01-01
A new thermoluminescence glow curve deconvolution (GCD) function is introduced which accurately describes second order thermoluminescence (TL) curves. The logistic asymmetric (LA) statistical probability function is used with the function variables being the maximum peak intensity (I m ), the temperature of the maximum peak intensity (T m ) and the LA width parameter a 2 . An analytical expression is derived from which the activation energy E can be calculated as a function of T m and the LA width parameter a 2 with an accuracy of 2% or better. The accuracy of the fit was tested for E values ranging from 0.7 to 2.5 eV, for s values between 10 5 and 10 25 s -1 , and for trap occupation number n 0 /N between 1 and 10 -6 . The goodness of fit of the logistic asymmetric function is described by the Figure of Merit (FOM) which is found to be of the order of 10 -2 . Preliminary results show that the GCD described here can easily be extended to the description of general order TL glow curves by varying the asymmetry parameter of the logistic asymmetric function. It is concluded that the TL kinetic analysis of first, second and general order TL glow curves can be performed with high accuracy and speed by using commercially available statistical packages that incorporate the Weibull and logistic asymmetric functions. (author)
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Anna Pascoletti
2010-12-01
Full Text Available We present some recent results on the existence of periodic solutions and chaotic like dynamics for second order scalar nonlinear ODEs. The equations under consideration belong to a simple class of perturbed planar Hamiltonian systems with slowly varying periodic coefficients, a typical example being given by the pendulum equation with moving support. Although there is already a broad literature on this subject, our approach, based on the concept of stretching along the paths, appears new in this context. In particular, our method is global in nature and stable with respect to small perturbations of the coefficients. Thus it applies even when some small friction terms are inserted into the equations. The main tool on which all our results are based is a topological lemma (that we call path crossing lemma which was already implicitly used by Poincaré (1883-1884 [51], as well as by Butler (1976 [8] and Conley (1975 [12] and subsequently “rediscovered” and applied in many different contexts. For this reason, the first part of this paper is devoted to a detailed exposition of the Crossing Lemma and its connections with other topological results.
A Truly Second-Order and Unconditionally Stable Thermal Lattice Boltzmann Method
Directory of Open Access Journals (Sweden)
Zhen Chen
2017-03-01
Full Text Available An unconditionally stable thermal lattice Boltzmann method (USTLBM is proposed in this paper for simulating incompressible thermal flows. In USTLBM, solutions to the macroscopic governing equations that are recovered from lattice Boltzmann equation (LBE through Chapman–Enskog (C-E expansion analysis are resolved in a predictor–corrector scheme and reconstructed within lattice Boltzmann framework. The development of USTLBM is inspired by the recently proposed simplified thermal lattice Boltzmann method (STLBM. Comparing with STLBM which can only achieve the first-order of accuracy in time, the present USTLBM ensures the second-order of accuracy both in space and in time. Meanwhile, all merits of STLBM are maintained by USTLBM. Specifically, USTLBM directly updates macroscopic variables rather than distribution functions, which greatly saves virtual memories and facilitates implementation of physical boundary conditions. Through von Neumann stability analysis, it can be theoretically proven that USTLBM is unconditionally stable. It is also shown in numerical tests that, comparing to STLBM, lower numerical error can be expected in USTLBM at the same mesh resolution. Four typical numerical examples are presented to demonstrate the robustness of USTLBM and its flexibility on non-uniform and body-fitted meshes.
McNeish, Daniel; Dumas, Denis
2017-01-01
Recent methodological work has highlighted the promise of nonlinear growth models for addressing substantive questions in the behavioral sciences. In this article, we outline a second-order nonlinear growth model in order to measure a critical notion in development and education: potential. Here, potential is conceptualized as having three components-ability, capacity, and availability-where ability is the amount of skill a student is estimated to have at a given timepoint, capacity is the maximum amount of ability a student is predicted to be able to develop asymptotically, and availability is the difference between capacity and ability at any particular timepoint. We argue that single timepoint measures are typically insufficient for discerning information about potential, and we therefore describe a general framework that incorporates a growth model into the measurement model to capture these three components. Then, we provide an illustrative example using the public-use Early Childhood Longitudinal Study-Kindergarten data set using a Michaelis-Menten growth function (reparameterized from its common application in biochemistry) to demonstrate our proposed model as applied to measuring potential within an educational context. The advantage of this approach compared to currently utilized methods is discussed as are future directions and limitations.
First- and second-order Raman scattering from MoTe2 single crystal
Caramazza, Simone; Collina, Arianna; Stellino, Elena; Ripanti, Francesca; Dore, Paolo; Postorino, Paolo
2018-02-01
We report on Raman experiments performed on a MoTe2 single crystal. The system belongs to the wide family of transition metal dichalcogenides which includes several of the most interesting two-dimensional materials for both basic and applied physics. Measurements were performed in the standard basal plane configuration, by placing the ab plane of the crystal perpendicular to the wave vector k i of the incident beam to explore the in-plane vibrational modes, and in the edge plane configuration with k i perpendicular to the crystal c axis, thus mainly exciting out-of-plane modes. For both configurations we performed a polarization-dependent study of the first-order Raman components and detailed computation of the corresponding selection rules. We were thus able to provide a complete assignment of the observed first-order Raman peaks, in agreement with previous literature results. A thorough analysis of the second-order Raman bands, as observed in both basal and edge plane configurations, provides new information and allows a precise assignment of these spectral structures. In particular, we have observed and assigned Raman active modes of the M point of the Brillouin zone previously predicted by ab initio calculations but never previously measured.
A stochastic collocation method for the second order wave equation with a discontinuous random speed
Motamed, Mohammad
2012-08-31
In this paper we propose and analyze a stochastic collocation method for solving the second order wave equation with a random wave speed and subjected to deterministic boundary and initial conditions. The speed is piecewise smooth in the physical space and depends on a finite number of random variables. The numerical scheme consists of a finite difference or finite element method in the physical space and a collocation in the zeros of suitable tensor product orthogonal polynomials (Gauss points) in the probability space. This approach leads to the solution of uncoupled deterministic problems as in the Monte Carlo method. We consider both full and sparse tensor product spaces of orthogonal polynomials. We provide a rigorous convergence analysis and demonstrate different types of convergence of the probability error with respect to the number of collocation points for full and sparse tensor product spaces and under some regularity assumptions on the data. In particular, we show that, unlike in elliptic and parabolic problems, the solution to hyperbolic problems is not in general analytic with respect to the random variables. Therefore, the rate of convergence may only be algebraic. An exponential/fast rate of convergence is still possible for some quantities of interest and for the wave solution with particular types of data. We present numerical examples, which confirm the analysis and show that the collocation method is a valid alternative to the more traditional Monte Carlo method for this class of problems. © 2012 Springer-Verlag.
Directory of Open Access Journals (Sweden)
Zool H. Ismail
2015-01-01
Full Text Available The main goal in developing closed loop control system for an Autonomous Underwater Vehicle (AUV is to make a robust vehicle from natural and exogenous perturbations such as wind, wave, and ocean currents. However a well-known robust control, for instance, Sliding Mode Controller (SMC, gives a chattering effect and it influences the stability of an AUV. Furthermore, some researchers combined other controls to get better result but it tends to present long computational time and causes large energy consumption. Thus, this paper proposed a Super Twisting Sliding Mode Controller (STSMC with dynamic region concept for an AUV. STSMC or a second order SMC is adopted as a robust controller which is free from chattering effect. Meanwhile, the implementation of dynamic region is useful to reduce the energy usage. As a result, the proposed controller obtains global asymptotic stability which is validated by using Lyapunov-like function. Moreover, some simulations present the efficiency of proposed controller. In conclusion, STSMC with region based control is effective to be applied for the robust tracking of an AUV. It contributes to give a fast response when handling the perturbations, short computational time, and low energy demand.
Second-order small-disturbance solutions for hypersonic flow over power-law bodies
Townsend, J. C.
1975-01-01
Similarity solutions were found which give the adiabatic flow of an ideal gas about two-dimensional and axisymmetric power-law bodies at infinite Mach number to second order in the body slenderness parameter. The flow variables were expressed as a sum of zero-order and perturbation similarity functions for which the axial variations in the flow equations separated out. The resulting similarity equations were integrated numerically. The solutions, which are universal functions, are presented in graphic and tabular form. To avoid a singularity in the calculations, the results are limited to body power-law exponents greater than about 0.85 for the two-dimensional case and 0.75 for the axisymmetric case. Because of the entropy layer induced by the nose bluntness (for power-law bodies other than cones and wedges), only the pressure function is valid at the body surface. The similarity results give excellent agreement with the exact solutions for inviscid flow over wedges and cones having half-angles up to about 20 deg. They give good agreement with experimental shock-wave shapes and surface-pressure distributions for 3/4-power axisymmetric bodies, considering that Mach number and boundary-layer displacement effects are not included in the theory.
Optimal design of PID controller for second order plus time delay systems
International Nuclear Information System (INIS)
Srivastava, S.; Misra, A.; Kumar, Y.; Thakur, S.K.
2015-01-01
It is well known that the effect of time delay in the forward path of control loop deteriorates the system performance and at the same time makes it difficult to compute the optimum PID controller parameters of the feedback control systems. PI/PID controller is most popular and used more than 80% in industries as well as in accelerators lab due to its simple structure and appropriate robustness. At VECC we have planned to use a PID controller for the speed control of DC motor which will be used to adjust the solenoid coil position of the 2.45 GHz microwave ion source for optimum performance during the online operation. In this paper we present a comparison of the two methods which have been used to design the optimum PID controller parameters: one by optimizing different time domain performance indices such as lAE, ITSE etc. and other using analytical formulation based on Linear Quadratic Regulator (LQR). We have performed numerical simulations using MATLAB and compare the closed loop time response performance measures using the PID parameters obtained from above mentioned two methods on a second order transfer function of a DC motor with time delay. (author)
Homoclinic Solutions for a Class of Second Order Nonautonomous Singular Hamiltonian Systems
Directory of Open Access Journals (Sweden)
Ziheng Zhang
2014-01-01
Full Text Available We are concerned with the existence of homoclinic solutions for the following second order nonautonomous singular Hamiltonian systems u¨+atWuu=0, (HS where -∞
Park, Hyunjin; Yang, Jin-ju; Seo, Jongbum; Choi, Yu-yong; Lee, Kun-ho; Lee, Jong-min
2014-04-01
Cortical features derived from magnetic resonance imaging (MRI) provide important information to account for human intelligence. Cortical thickness, surface area, sulcal depth, and mean curvature were considered to explain human intelligence. One region of interest (ROI) of a cortical structure consisting of thousands of vertices contained thousands of measurements, and typically, one mean value (first order moment), was used to represent a chosen ROI, which led to a potentially significant loss of information. We proposed a technological improvement to account for human intelligence in which a second moment (variance) in addition to the mean value was adopted to represent a chosen ROI, so that the loss of information would be less severe. Two computed moments for the chosen ROIs were analyzed with partial least squares regression (PLSR). Cortical features for 78 adults were measured and analyzed in conjunction with the full-scale intelligence quotient (FSIQ). Our results showed that 45% of the variance of the FSIQ could be explained using the combination of four cortical features using two moments per chosen ROI. Our results showed improvement over using a mean value for each ROI, which explained 37% of the variance of FSIQ using the same set of cortical measurements. Our results suggest that using additional second order moments is potentially better than using mean values of chosen ROIs for regression analysis to account for human intelligence. Copyright © 2014 Elsevier Ltd. All rights reserved.
A canonical averaging in the second-order quantized Hamilton dynamics
International Nuclear Information System (INIS)
Heatwole, Eric; Prezhdo, Oleg V.
2004-01-01
Quantized Hamilton dynamics (QHD) is a simple and elegant extension of classical Hamilton dynamics that accurately includes zero-point energy, tunneling, dephasing, and other quantum effects. Formulated as a hierarchy of approximations to exact quantum dynamics in the Heisenberg formulation, QHD has been used to study evolution of observables subject to a single initial condition. In present, we develop a practical solution for generating canonical ensembles in the second-order QHD for position and momentum operators, which can be mapped onto classical phase space in doubled dimensionality and which in certain limits is equivalent to thawed Gaussian. We define a thermal distribution in the space of the QHD-2 variables and show that the standard β=1/kT relationship becomes β ' =2/kT in the high temperature limit due to an overcounting of states in the extended phase space, and a more complicated function at low temperatures. The QHD thermal distribution is used to compute total energy, kinetic energy, heat capacity, and other canonical averages for a series of quartic potentials, showing good agreement with the quantum results
First and second order quantum phase transitions in multi-band superconductors
Energy Technology Data Exchange (ETDEWEB)
Padilha, Igor T., E-mail: igorfis@if.uff.b [Instituto de Fisica, Universidade Federal Fluminense, Campus da Praia Vermelha, Niteroi, RJ 24.210-340 (Brazil); Continentino, M.A. [Instituto de Fisica, Universidade Federal Fluminense, Campus da Praia Vermelha, Niteroi, RJ 24.210-340 (Brazil)
2009-10-15
In multi-band and inter-metallic materials superconductivity can be destroyed by applying external pressure in these systems. In many cases the critical temperature is driven continuously to zero, the superconducting to normal transition being associated with a superconducting quantum critical point (SQCP). In this paper we propose a model for this type of SQCP based on the increase of hybridization as pressure is applied in the material. We study a two-band superconductor with hybridization V between these bands. We use a BCS approximation and include both inter- and intra-band attractive interactions. We show that for negligible inter-band interactions, as hybridization increases there is a second order phase transition from a superconductor to a normal state at zero temperature at a critical value of the hybridization V{sub c}. This SQCP can be reached by pressure, since this external parameter controls hybridization in the system. We also find discontinuous transitions at zero temperature and the appearance of a gapless superconducting (GS) phase in a certain range of hybridization in the case of inter-band interactions being dominant.
Digital Inequality and Second-Order Disasters: Social Media in the Typhoon Haiyan Recovery
Directory of Open Access Journals (Sweden)
Mirca Madianou
2015-09-01
Full Text Available This article investigates the intersection of digital and social inequality in the context of disaster recovery. In doing so, the article responds to the optimism present in recent claims about “humanitarian technology” which refers to the empowering uses and applications of interactive technologies by disaster-affected people. Drawing on a long-term ethnography with affected communities recovering from Typhoon Haiyan that hit the Philippines in 2013 triggering a massive humanitarian response, the article offers a grounded assessment of the role of social media in disaster recovery. In particular, the article focuses on whether any positive consequences associated with digital media use are equally spread among better off and socially marginalized participants. The analysis reveals sharp digital inequalities which map onto existing social inequalities. While some of our already better-off participants have access to a rich media landscape which they are able to navigate often reaping significant benefits, low-income participants are trapped in a delayed recovery with diminished social media opportunities. The fact that some participants are using social media to recover at a rapid pace while others are languishing behind represents a deepening of social inequalities. In this sense, digital inequality can amplify social inequalities leading to a potential “second-order disaster.” This refers to humanly perpetuated disasters that can even surpass the effects of the natural disaster.
Directory of Open Access Journals (Sweden)
Guoguang Wen
2014-01-01
Full Text Available This paper mainly addresses the distributed consensus tracking problem for second-order nonlinear multiagent systems with a specified reference trajectory. The dynamics of each follower consists of two terms: nonlinear inherent dynamics and a simple communication protocol relying only on the position and velocity information of its neighbors. The consensus reference is taken as a virtual leader, whose output is only its position and velocity information that is available to only a subset of a group of followers. To achieve consensus tracking, a class of nonsmooth control protocols is proposed which reply on the relative information among the neighboring agents. Then some corresponding sufficient conditions are derived. It is shown that if the communication graph associated with the virtual leader and followers is connected at each time instant, the consensus can be achieved at least globally exponentially with the proposed protocol. Rigorous proofs are given by using graph theory, matrix theory, and Lyapunov theory. Finally, numerical examples are presented to illustrate the theoretical analysis.
Transsynaptic Mapping of Second-Order Taste Neurons in Flies by trans-Tango.
Talay, Mustafa; Richman, Ethan B; Snell, Nathaniel J; Hartmann, Griffin G; Fisher, John D; Sorkaç, Altar; Santoyo, Juan F; Chou-Freed, Cambria; Nair, Nived; Johnson, Mark; Szymanski, John R; Barnea, Gilad
2017-11-15
Mapping neural circuits across defined synapses is essential for understanding brain function. Here we describe trans-Tango, a technique for anterograde transsynaptic circuit tracing and manipulation. At the core of trans-Tango is a synthetic signaling pathway that is introduced into all neurons in the animal. This pathway converts receptor activation at the cell surface into reporter expression through site-specific proteolysis. Specific labeling is achieved by presenting a tethered ligand at the synapses of genetically defined neurons, thereby activating the pathway in their postsynaptic partners and providing genetic access to these neurons. We first validated trans-Tango in the Drosophila olfactory system and then implemented it in the gustatory system, where projections beyond the first-order receptor neurons are not fully characterized. We identified putative second-order neurons within the sweet circuit that include projection neurons targeting known neuromodulation centers in the brain. These experiments establish trans-Tango as a flexible platform for transsynaptic circuit analysis. Copyright © 2017 Elsevier Inc. All rights reserved.
A Global Strategy for Human Development: An Example of Second Order Science
Directory of Open Access Journals (Sweden)
Stuart A. Umpleby
2016-10-01
Full Text Available In the 1960s the Institute of Cultural Affairs, based in Chicago, Illinois, started working with poor communities, helping people work together to achieve positive change. They developed some very useful methods for facilitating group conversations. They then used these methods in poor communities around the world. They returned each summer to Chicago to discuss what worked and what did not. They would modify their methods, plan the next year's activities, implement the activities, then come together the following summer to discuss successes and learnings. Academics do something similar with annual conferences, but they focus on publishing academic articles rather than on improving the lives of real people in real communities. Part of the motivation for defining and creating second order science is to increase attention to innovative, problem-solving social actions, often conducted by Non-Governmental Organizations. Currently universities have large numbers of students and faculty members seeking to advance knowledge in the social sciences, using a conception of science taken from the physical sciences. But social systems are composed of thinking participants, not inanimate objects. In addition to searching for reliable cause and effect relationships, part of social science research could be devoted to developing conversational methods that aid joint action toward shared goals. If this goal were accepted within the social sciences in universities, there would be a large increase in the number of people working to improve social systems and developing more effective conversational methods.
Temporal mode selectivity by frequency conversion in second-order nonlinear optical waveguides
DEFF Research Database (Denmark)
Reddy, D. V.; Raymer, M. G.; McKinstrie, C. J.
2013-01-01
We explore theoretically the feasibility of using frequency conversion by sum- or difference-frequency generation, enabled by three-wave-mixing, for selectively multiplexing orthogonal input waveforms that overlap in time and frequency. Such a process would enable a drop device for use in a trans......We explore theoretically the feasibility of using frequency conversion by sum- or difference-frequency generation, enabled by three-wave-mixing, for selectively multiplexing orthogonal input waveforms that overlap in time and frequency. Such a process would enable a drop device for use...... in a transparent optical network using temporally orthogonal waveforms to encode different channels. We model the process using coupled-mode equations appropriate for wave mixing in a uniform second-order nonlinear optical medium pumped by a strong laser pulse. We find Green functions describing the process......, and employ Schmidt (singular-value) decompositions thereof to quantify its viability in functioning as a coherent waveform discriminator. We define a selectivity figure of merit in terms of the Schmidt coefficients, and use it to compare and contrast various parameter regimes via extensive numerical...
First and second order semi-Markov chains for wind speed modeling
Prattico, F.; Petroni, F.; D'Amico, G.
2012-04-01
The increasing interest in renewable energy leads scientific research to find a better way to recover most of the available energy. Particularly, the maximum energy recoverable from wind is equal to 59.3% of that available (Betz law) at a specific pitch angle and when the ratio between the wind speed in output and in input is equal to 1/3. The pitch angle is the angle formed between the airfoil of the blade of the wind turbine and the wind direction. Old turbine and a lot of that actually marketed, in fact, have always the same invariant geometry of the airfoil. This causes that wind turbines will work with an efficiency that is lower than 59.3%. New generation wind turbines, instead, have a system to variate the pitch angle by rotating the blades. This system able the wind turbines to recover, at different wind speed, always the maximum energy, working in Betz limit at different speed ratios. A powerful system control of the pitch angle allows the wind turbine to recover better the energy in transient regime. A good stochastic model for wind speed is then needed to help both the optimization of turbine design and to assist the system control to predict the value of the wind speed to positioning the blades quickly and correctly. The possibility to have synthetic data of wind speed is a powerful instrument to assist designer to verify the structures of the wind turbines or to estimate the energy recoverable from a specific site. To generate synthetic data, Markov chains of first or higher order are often used [1,2,3]. In particular in [3] is presented a comparison between a first-order Markov chain and a second-order Markov chain. A similar work, but only for the first-order Markov chain, is conduced by [2], presenting the probability transition matrix and comparing the energy spectral density and autocorrelation of real and synthetic wind speed data. A tentative to modeling and to join speed and direction of wind is presented in [1], by using two models, first
About sign-constancy of Green's functions for impulsive second order delay equations
Directory of Open Access Journals (Sweden)
Alexander Domoshnitsky
2014-01-01
Full Text Available We consider the following second order differential equation with delay \\[\\begin{cases} (Lx(t\\equiv{x''(t+\\sum_{j=1}^p {b_{j}(tx(t-\\theta_{j}(t}}=f(t, \\quad t\\in[0,\\omega],\\\\ x(t_j=\\gamma_{j}x(t_j-0, x'(t_j=\\delta_{j}x'(t_j-0, \\quad j=1,2,\\ldots,r. \\end{cases}\\] In this paper we find necessary and sufficient conditions of positivity of Green's functions for this impulsive equation coupled with one or two-point boundary conditions in the form of theorems about differential inequalities. By choosing the test function in these theorems, we obtain simple sufficient conditions. For example, the inequality \\(\\sum_{i=1}^p{b_i(t\\left(\\frac{1}{4}+r\\right}\\lt \\frac{2}{\\omega^2}\\ is a basic one, implying negativity of Green's function of two-point problem for this impulsive equation in the case \\(0\\lt \\gamma_i\\leq{1}\\, \\(0\\lt \\delta_i\\leq{1}\\ for \\(i=1,\\ldots ,p\\.
Electro-osmosis of nematic liquid crystals under weak anchoring and second-order surface effects
Poddar, Antarip; Dhar, Jayabrata; Chakraborty, Suman
2017-07-01
Advent of nematic liquid crystal flows has attracted renewed attention in view of microfluidic transport phenomena. Among various transport processes, electro-osmosis stands as one of the efficient flow actuation mechanisms through narrow confinements. In the present study, we explore the electrically actuated flow of an ordered nematic fluid with ionic inclusions, taking into account the influences from surface-induced elasticity and electrical double layer (EDL) phenomena. Toward this, we devise the coupled flow governing equations from fundamental free-energy analysis, considering the contributions from first- and second-order elastic, dielectric, flexoelectric, charged surface polarization, ionic and entropic energies. The present study focuses on the influence of surface charge and elasticity effects in the resulting linear electro-osmosis through a slit-type microchannel whose surfaces are chemically treated to display a homeotropic-type weak anchoring state. An optical periodic stripe configuration of the nematic director has been observed, especially for higher electric fields, wherein the Ericksen number for the dynamic study is restricted to the order of unity. Contrary to the isotropic electrolytes, the EDL potential in this case was found to be dependent on the external field strength. Through a systematic investigation, we brought out the fact that the wavelength of the oscillating patterns is dictated mainly by the external field, while the amplitude depends on most of the physical variables ranging from the anchoring strength and the flexoelectric coefficients to the surface charge density and electrical double layer thickness.
Short-range second order screened exchange correction to RPA correlation energies
Beuerle, Matthias; Ochsenfeld, Christian
2017-11-01
Direct random phase approximation (RPA) correlation energies have become increasingly popular as a post-Kohn-Sham correction, due to significant improvements over DFT calculations for properties such as long-range dispersion effects, which are problematic in conventional density functional theory. On the other hand, RPA still has various weaknesses, such as unsatisfactory results for non-isogyric processes. This can in parts be attributed to the self-correlation present in RPA correlation energies, leading to significant self-interaction errors. Therefore a variety of schemes have been devised to include exchange in the calculation of RPA correlation energies in order to correct this shortcoming. One of the most popular RPA plus exchange schemes is the second order screened exchange (SOSEX) correction. RPA + SOSEX delivers more accurate absolute correlation energies and also improves upon RPA for non-isogyric processes. On the other hand, RPA + SOSEX barrier heights are worse than those obtained from plain RPA calculations. To combine the benefits of RPA correlation energies and the SOSEX correction, we introduce a short-range RPA + SOSEX correction. Proof of concept calculations and benchmarks showing the advantages of our method are presented.
Nonself-Adjoint Second-Order Difference Operators in Limit-Circle Cases
Directory of Open Access Journals (Sweden)
Bilender P. Allahverdiev
2012-01-01
Full Text Available We consider the maximal dissipative second-order difference (or discrete Sturm-Liouville operators acting in the Hilbert space ℓ2(ℤ (ℤ:={0,±1,±2,…}, that is, the extensions of a minimal symmetric operator with defect index (2,2 (in the Weyl-Hamburger limit-circle cases at ±∞. We investigate two classes of maximal dissipative operators with separated boundary conditions, called “dissipative at −∞” and “dissipative at ∞.” In each case, we construct a self-adjoint dilation of the maximal dissipative operator and its incoming and outgoing spectral representations, which make it possible to determine the scattering matrix of the dilation. We also establish a functional model of the maximal dissipative operator and determine its characteristic function through the Titchmarsh-Weyl function of the self-adjoint operator. We prove the completeness of the system of eigenvectors and associated vectors of the maximal dissipative operators.
Short-range second order screened exchange correction to RPA correlation energies.
Beuerle, Matthias; Ochsenfeld, Christian
2017-11-28
Direct random phase approximation (RPA) correlation energies have become increasingly popular as a post-Kohn-Sham correction, due to significant improvements over DFT calculations for properties such as long-range dispersion effects, which are problematic in conventional density functional theory. On the other hand, RPA still has various weaknesses, such as unsatisfactory results for non-isogyric processes. This can in parts be attributed to the self-correlation present in RPA correlation energies, leading to significant self-interaction errors. Therefore a variety of schemes have been devised to include exchange in the calculation of RPA correlation energies in order to correct this shortcoming. One of the most popular RPA plus exchange schemes is the second order screened exchange (SOSEX) correction. RPA + SOSEX delivers more accurate absolute correlation energies and also improves upon RPA for non-isogyric processes. On the other hand, RPA + SOSEX barrier heights are worse than those obtained from plain RPA calculations. To combine the benefits of RPA correlation energies and the SOSEX correction, we introduce a short-range RPA + SOSEX correction. Proof of concept calculations and benchmarks showing the advantages of our method are presented.
A Combined First and Second Order Variational Approach for Image Reconstruction
Papafitsoros, K.
2013-05-10
In this paper we study a variational problem in the space of functions of bounded Hessian. Our model constitutes a straightforward higher-order extension of the well known ROF functional (total variation minimisation) to which we add a non-smooth second order regulariser. It combines convex functions of the total variation and the total variation of the first derivatives. In what follows, we prove existence and uniqueness of minimisers of the combined model and present the numerical solution of the corresponding discretised problem by employing the split Bregman method. The paper is furnished with applications of our model to image denoising, deblurring as well as image inpainting. The obtained numerical results are compared with results obtained from total generalised variation (TGV), infimal convolution and Euler\\'s elastica, three other state of the art higher-order models. The numerical discussion confirms that the proposed higher-order model competes with models of its kind in avoiding the creation of undesirable artifacts and blocky-like structures in the reconstructed images-a known disadvantage of the ROF model-while being simple and efficiently numerically solvable. ©Springer Science+Business Media New York 2013.
On the origin of the second-order nonlinearity in strained Si-SiN structures
Khurgin, J. B.; Stievater, T. H.; Pruessner, M. W.; Rabinovich, W. S.
2015-12-01
The development of efficient low-loss electro-optic and nonlinear components based on silicon or its related compounds, such as nitrides and oxides, is expected to dramatically enhance silicon photonics by eliminating the need for non-CMOS-compatible materials. While bulk Si is centrosymmetric and thus displays no second-order (\\c{hi}(2)) effects, a body of experimental evidence accumulated in the last decade demonstrates that when a strain gradient is present, a significant \\c{hi}(2) and Pockels coefficient can be observed. In this work we connect a strain-gradient-induced \\c{hi}(2) with another strain-gradient-induced phenomenon, the flexoelectric effect. We show that even in the presence of an extremely strong strain gradient, the degree by which a nonpolar material like Si can be altered cannot possibly explain the order of magnitude of observed chi^(2) phenomena. At the same time, in a polar material like SiN, each bond has a large nonlinear polarizability, so when the inversion symmetry is broken by a strain gradient, a small (few degrees) re-orientation of bonds can engender chi^(2) of the magnitude observed experimentally. It is our view therefore that the origin of the nonlinear and electro-optic effects in strained Si structures lies in not in the Si itself, but in the material providing the strain: the silicon nitride cladding.
Britzger, Michael; Wimmer, Maximilian H; Khalaidovski, Alexander; Friedrich, Daniel; Kroker, Stefanie; Brückner, Frank; Kley, Ernst-Bernhard; Tünnermann, Andreas; Danzmann, Karsten; Schnabel, Roman
2012-11-05
Michelson-type laser-interferometric gravitational-wave (GW) observatories employ very high light powers as well as transmissively-coupled Fabry-Perot arm resonators in order to realize high measurement sensitivities. Due to the absorption in the transmissive optics, high powers lead to thermal lensing and hence to thermal distortions of the laser beam profile, which sets a limit on the maximal light power employable in GW observatories. Here, we propose and realize a Michelson-type laser interferometer with arm resonators whose coupling components are all-reflective second-order Littrow gratings. In principle such gratings allow high finesse values of the resonators but avoid bulk transmission of the laser light and thus the corresponding thermal beam distortion. The gratings used have three diffraction orders, which leads to the creation of a second signal port. We theoretically analyze the signal response of the proposed topology and show that it is equivalent to a conventional Michelson-type interferometer. In our proof-of-principle experiment we generated phase-modulation signals inside the arm resonators and detected them simultaneously at the two signal ports. The sum signal was shown to be equivalent to a single-output-port Michelson interferometer with transmissively-coupled arm cavities, taking into account optical loss. The proposed and demonstrated topology is a possible approach for future all-reflective GW observatory designs.
Heterogeneous traffic flow modelling using second-order macroscopic continuum model
Mohan, Ranju; Ramadurai, Gitakrishnan
2017-01-01
Modelling heterogeneous traffic flow lacking in lane discipline is one of the emerging research areas in the past few years. The two main challenges in modelling are: capturing the effect of varying size of vehicles, and the lack in lane discipline, both of which together lead to the 'gap filling' behaviour of vehicles. The same section length of the road can be occupied by different types of vehicles at the same time, and the conventional measure of traffic concentration, density (vehicles per lane per unit length), is not a good measure for heterogeneous traffic modelling. First aim of this paper is to have a parsimonious model of heterogeneous traffic that can capture the unique phenomena of gap filling. Second aim is to emphasize the suitability of higher-order models for modelling heterogeneous traffic. Third, the paper aims to suggest area occupancy as concentration measure of heterogeneous traffic lacking in lane discipline. The above mentioned two main challenges of heterogeneous traffic flow are addressed by extending an existing second-order continuum model of traffic flow, using area occupancy for traffic concentration instead of density. The extended model is calibrated and validated with field data from an arterial road in Chennai city, and the results are compared with those from few existing generalized multi-class models.
National Research Council Canada - National Science Library
Sweetman, Bert
1999-01-01
WAVEMAKER is a FORTRAN program used to simulate random nonGaussian ocean wave histories, to identify the underlying first- and second- order components of user specified waves, or to predict wave time...
Run-up on a structure due to second-order waves and current in a numerical wave tank
DEFF Research Database (Denmark)
Buchmann, Bjarne; Skourup, Jesper; Cheung, Kwok Fai
1998-01-01
A numerical wave tank is considered in which the interaction between waves, current and a structure is simulated by a 3D boundary element model in the time domain. Through a Taylor series expansion and a perturbation procedure the model is formulated to second order in wave steepness and to first....... For the simulations a bottom mounted vertical circular cylinder is chosen. The numerical results show good agreement with previous analytical and numerical solutions for second-order wave diffraction without a current and first-order wave diffraction with a collinear current. The inclusion of a current...... in the calculation of second-order wave run-up is new and the validity of the results is demonstrated by a parametric study. It is shown that both the current and the second-order wave components are of significant importance in calculating magnitude and location of the maximum run-up on a structure. (C) 1998...
Czech Academy of Sciences Publication Activity Database
Somer, L.; Křížek, Michal
2017-01-01
Roč. 55, č. 3 (2017), s. 209-228 ISSN 0015-0517 Institutional support: RVO:67985840 Keywords : Lucas sequence * second-order * Fibonacci sequence Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics
Ha Minh, H.; Viegas, J. R.; Rubesin, M. W.; Spalart, P.; Vandromme, D. D.
1989-01-01
The turbulent boundary layer under a freestream whose velocity varies sinusoidally in time around a zero mean is computed using two second order turbulence closure models. The time or phase dependent behavior of the Reynolds stresses are analyzed and results are compared to those of a previous SPALART-BALDWIN direct simulation. Comparisons show that the second order modeling is quite satisfactory for almost all phase angles, except in the relaminarization period where the computations lead to a relatively high wall shear stress.
A semi-implicit, second-order-accurate numerical model for multiphase underexpanded volcanic jets
Directory of Open Access Journals (Sweden)
S. Carcano
2013-11-01
Full Text Available An improved version of the PDAC (Pyroclastic Dispersal Analysis Code, Esposti Ongaro et al., 2007 numerical model for the simulation of multiphase volcanic flows is presented and validated for the simulation of multiphase volcanic jets in supersonic regimes. The present version of PDAC includes second-order time- and space discretizations and fully multidimensional advection discretizations in order to reduce numerical diffusion and enhance the accuracy of the original model. The model is tested on the problem of jet decompression in both two and three dimensions. For homogeneous jets, numerical results are consistent with experimental results at the laboratory scale (Lewis and Carlson, 1964. For nonequilibrium gas–particle jets, we consider monodisperse and bidisperse mixtures, and we quantify nonequilibrium effects in terms of the ratio between the particle relaxation time and a characteristic jet timescale. For coarse particles and low particle load, numerical simulations well reproduce laboratory experiments and numerical simulations carried out with an Eulerian–Lagrangian model (Sommerfeld, 1993. At the volcanic scale, we consider steady-state conditions associated with the development of Vulcanian and sub-Plinian eruptions. For the finest particles produced in these regimes, we demonstrate that the solid phase is in mechanical and thermal equilibrium with the gas phase and that the jet decompression structure is well described by a pseudogas model (Ogden et al., 2008. Coarse particles, on the other hand, display significant nonequilibrium effects, which associated with their larger relaxation time. Deviations from the equilibrium regime, with maximum velocity and temperature differences on the order of 150 m s−1 and 80 K across shock waves, occur especially during the rapid acceleration phases, and are able to modify substantially the jet dynamics with respect to the homogeneous case.
Second order method for solving 3D elasticity equations with complex interfaces
Wang, Bao; Xia, Kelin; Wei, Guo-Wei
2015-08-01
Elastic materials are ubiquitous in nature and indispensable components in man-made devices and equipments. When a device or equipment involves composite or multiple elastic materials, elasticity interface problems come into play. The solution of three-dimensional (3D) elasticity interface problems is significantly more difficult than that of elliptic counterparts due to the coupled vector components and cross derivatives in the governing elasticity equations. This work introduces the matched interface and boundary (MIB) method for solving 3D elasticity interface problems. The proposed MIB elasticity interface scheme utilizes fictitious values on irregular grid points near the material interface to replace function values in the discretization so that the elasticity equation can be discretized using the standard finite difference schemes as if there were no material interface. The interface jump conditions are rigorously enforced on the intersecting points between the interface and the mesh lines. Such an enforcement determines the fictitious values. A number of new techniques have been developed to construct efficient MIB elasticity interface schemes for dealing with cross derivative in coupled governing equations. The proposed method is extensively validated over both weak and strong discontinuities of the solution, both piecewise constant and position-dependent material parameters, both smooth and nonsmooth interface geometries, and both small and large contrasts in the Poisson's ratio and shear modulus across the interface. Numerical experiments indicate that the present MIB method is of second order convergence in both L∞ and L2 error norms for handling arbitrarily complex interfaces, including biomolecular surfaces. To our best knowledge, this is the first elasticity interface method that is able to deliver the second convergence for the molecular surfaces of proteins.
Robust second-order scheme for multi-phase flow computations
Shahbazi, Khosro
2017-06-01
A robust high-order scheme for the multi-phase flow computations featuring jumps and discontinuities due to shock waves and phase interfaces is presented. The scheme is based on high-order weighted-essentially non-oscillatory (WENO) finite volume schemes and high-order limiters to ensure the maximum principle or positivity of the various field variables including the density, pressure, and order parameters identifying each phase. The two-phase flow model considered besides the Euler equations of gas dynamics consists of advection of two parameters of the stiffened-gas equation of states, characterizing each phase. The design of the high-order limiter is guided by the findings of Zhang and Shu (2011) [36], and is based on limiting the quadrature values of the density, pressure and order parameters reconstructed using a high-order WENO scheme. The proof of positivity-preserving and accuracy is given, and the convergence and the robustness of the scheme are illustrated using the smooth isentropic vortex problem with very small density and pressure. The effectiveness and robustness of the scheme in computing the challenging problem of shock wave interaction with a cluster of tightly packed air or helium bubbles placed in a body of liquid water is also demonstrated. The superior performance of the high-order schemes over the first-order Lax-Friedrichs scheme for computations of shock-bubble interaction is also shown. The scheme is implemented in two-dimensional space on parallel computers using message passing interface (MPI). The proposed scheme with limiter features approximately 50% higher number of inter-processor message communications compared to the corresponding scheme without limiter, but with only 10% higher total CPU time. The scheme is provably second-order accurate in regions requiring positivity enforcement and higher order in the rest of domain.
International Nuclear Information System (INIS)
Gougam, L.A.; Taibi, H.; Chikhi, A.; Mekideche-Chafa, F.
2009-01-01
The problem of determining the analytical description for a set of data arises in numerous sciences and applications and can be referred to as data modeling or system identification. Neural networks are a convenient means of representation because they are known to be universal approximates that can learn data. The desired task is usually obtained by a learning procedure which consists in adjusting the s ynaptic weights . For this purpose, many learning algorithms have been proposed to update these weights. The convergence for these learning algorithms is a crucial criterion for neural networks to be useful in different applications. The aim of the present contribution is to use a training algorithm for feed forward wavelet networks used for function approximation. The training is based on the minimization of the least-square cost function. The minimization is performed by iterative second order gradient-based methods. We make use of the Levenberg-Marquardt algorithm to train the architecture of the chosen network and, then, the training procedure starts with a simple gradient method which is followed by a BFGS (Broyden, Fletcher, Glodfarb et Shanno) algorithm. The performances of the two algorithms are then compared. Our method is then applied to determine the energy of the ground state associated to a sextic potential. In fact, the Schrodinger equation does not always admit an exact solution and one has, generally, to solve it numerically. To this end, the sextic potential is, firstly, approximated with the above outlined wavelet network and, secondly, implemented into a numerical scheme. Our results are in good agreement with the ones found in the literature.
Blind ICA detection based on second-order cone programming for MC-CDMA systems
Jen, Chih-Wei; Jou, Shyh-Jye
2014-12-01
The multicarrier code division multiple access (MC-CDMA) technique has received considerable interest for its potential application to future wireless communication systems due to its high data rate. A common problem regarding the blind multiuser detectors used in MC-CDMA systems is that they are extremely sensitive to the complex channel environment. Besides, the perturbation of colored noise may negatively affect the performance of the system. In this paper, a new coherent detection method will be proposed, which utilizes the modified fast independent component analysis (FastICA) algorithm, based on approximate negentropy maximization that is subject to the second-order cone programming (SOCP) constraint. The aim of the proposed coherent detection is to provide robustness against small-to-medium channel estimation mismatch (CEM) that may arise from channel frequency response estimation error in the MC-CDMA system, which is modulated by downlink binary phase-shift keying (BPSK) under colored noise. Noncoherent demodulation schemes are preferable to coherent demodulation schemes, as the latter are difficult to implement over time-varying fading channels. Differential phase-shift keying (DPSK) is therefore the natural choice for an alternative modulation scheme. Furthermore, the new blind differential SOCP-based ICA (SOCP-ICA) detection without channel estimation and compensation will be proposed to combat Doppler spread caused by time-varying fading channels in the DPSK-modulated MC-CDMA system under colored noise. In this paper, numerical simulations are used to illustrate the robustness of the proposed blind coherent SOCP-ICA detector against small-to-medium CEM and to emphasize the advantage of the blind differential SOCP-ICA detector in overcoming Doppler spread.
Garcia-Fernandez, M.; Desai, S. D.; Butala, M. D.; Komjathy, A.
2013-12-01
This work evaluates various approaches to compute the second order ionospheric correction (SOIC) to Global Positioning System (GPS) measurements. When estimating the reference frame using GPS, applying this correction is known to primarily affect the realization of the origin of the Earth's reference frame along the spin axis (Z coordinate). Therefore, the Z translation relative to the International Terrestrial Reference Frame 2008 is used as the metric to evaluate various published approaches to determining the slant total electron content (TEC) for the SOIC: getting the slant TEC from GPS measurements, and using the vertical total electron content (TEC) given by a Global Ionospheric Model (GIM) to transform it to slant TEC via a mapping function. All of these approaches agree to 1 mm if the ionospheric shell height needed in GIM-based approaches is set to 600 km. The commonly used shell height of 450 km introduces an offset of 1 to 2 mm. When the SOIC is not applied, the Z axis translation can be reasonably modeled with a ratio of +0.23 mm/TEC units of the daily median GIM vertical TEC. Also, precise point positioning (PPP) solutions (positions and clocks) determined with and without SOIC differ by less than 1 mm only if they are based upon GPS orbit and clock solutions that have consistently applied or not applied the correction, respectively. Otherwise, deviations of few millimeters in the north component of the PPP solutions can arise due to inconsistencies with the satellite orbit and clock products, and those deviations exhibit a dependency on solar cycle conditions.
Mattonen, Sarah A.; Palma, David A.; Haasbeek, Cornelis J. A.; Senan, Suresh; Ward, Aaron D.
2014-03-01
Benign radiation-induced lung injury is a common finding following stereotactic ablative radiotherapy (SABR) for lung cancer, and is often difficult to differentiate from a recurring tumour due to the ablative doses and highly conformal treatment with SABR. Current approaches to treatment response assessment have shown limited ability to predict recurrence within 6 months of treatment. The purpose of our study was to evaluate the accuracy of second order texture statistics for prediction of eventual recurrence based on computed tomography (CT) images acquired within 6 months of treatment, and compare with the performance of first order appearance and lesion size measures. Consolidative and ground-glass opacity (GGO) regions were manually delineated on post-SABR CT images. Automatic consolidation expansion was also investigated to act as a surrogate for GGO position. The top features for prediction of recurrence were all texture features within the GGO and included energy, entropy, correlation, inertia, and first order texture (standard deviation of density). These predicted recurrence with 2-fold cross validation (CV) accuracies of 70-77% at 2- 5 months post-SABR, with energy, entropy, and first order texture having leave-one-out CV accuracies greater than 80%. Our results also suggest that automatic expansion of the consolidation region could eliminate the need for manual delineation, and produced reproducible results when compared to manually delineated GGO. If validated on a larger data set, this could lead to a clinically useful computer-aided diagnosis system for prediction of recurrence within 6 months of SABR and allow for early salvage therapy for patients with recurrence.
Linear reversible second-order cellular automata and their first-order matrix equivalents
International Nuclear Information System (INIS)
Macfarlane, A J
2004-01-01
Linear or one-dimensional reversible second-order cellular automata, exemplified by three cases named as RCA1-3, are introduced. Displays of their evolution in discrete time steps, t=0, 1, 2, ..., from their simplest initial states and on the basis of updating rules in modulo 2 arithmetic, are presented. In these, shaded and unshaded squares denote cells whose cell variables are equal to one and zero respectively. This paper is devoted to finding general formulas for, and explicit numerical evaluations of, the weights N(t) of the states or configurations of RCA1-3, i.e. the total number of shaded cells in tth line of their displays. This is achieved by means of the replacement of RCA1-3 by the equivalent linear first-order matrix automata MCA1-3, for which the cell variables are 2x2 matrices, instead of just numbers (element of Z 2 ) as for RCA1-3. MCA1-3 are tractable because it has been possible to generalize to them the heavy duty methods already well-developed for ordinary first-order cellular automata like those of Wolfram's Rules 90 and 150. While the automata MCA1-3 are thought to be of genuine interest in their own right, with untapped further mathematical potential, their treatment has been applied here to expediting derivation of a large body of general and explicit results for N(t) for RCA1-3. Amongst explicit results obtained are formulas also for each of RCA1-3 for the total weight of the configurations of the first 2 M times, M=0, 1, 2, ..
Light-induced second-order nonlinear optical properties of molecular materials
International Nuclear Information System (INIS)
Fiorini, Celine
1995-01-01
We present a theoretical and experimental study of all-optical orientation. The work focusses more particularly on the realization of poled polymers for quadratic nonlinear optics. It is shown that the coherent superposition of two beams at fundamental and second harmonic frequencies results in the breaking of the former centro-symmetry of the material. The source is a Neodymium-YAG laser delivering 25 ps pulses at 1064 nm. The incident second-harmonic beam is obtained by frequency doubling in a KDP crystal. Using a phase conjugation configuration based on six-wave mixing interactions, we have Investigated in detail the mechanism of photo-induced second-harmonic generation in initially centrosymmetric materials. It is shown that the light-induced non-centro-symmetry is due to an orientational hole burning of the molecules. The process involves interference effects between one and two photon absorptions. Experiments are performed in various solutions of an azo-dye molecule (Disperse Red One). The possibility of inducing quasi-permanent second-order susceptibility in a PMMA polymer matrix doped with the azo-dye molecule of Disperse Red One is also demonstrated. The method of all-optical poling consists in a seeding type process with alternate writing and probing phases. Permanent orientation of the molecules can be described in terms of photo-isomerization processes. It leads to a poling of the molecules with a spatial modulation which is phase-matched for frequency doubling. Relevant parameters leading to an efficient polarisation of the sample are identified. A theoretical modelling of the different phenomena observed is proposed. Last part of the study is devoted to an enlarged study of the potentialities offered by this dual-frequency holography technique: orientation of octupolar molecules, polarisation of highly transparent materials. We also show that the new techniques developed during this work can also reveal to be complementary methods for nonlinear
Yu, Jun; Hao, Du; Li, Decai
2018-01-01
The phenomenon whereby an object whose density is greater than magnetic fluid can be suspended stably in magnetic fluid under the magnetic field is one of the peculiar properties of magnetic fluids. Examples of applications based on the peculiar properties of magnetic fluid are sensors and actuators, dampers, positioning systems and so on. Therefore, the calculation and measurement of magnetic levitation force of magnetic fluid is of vital importance. This paper concerns the peculiar second-order buoyancy experienced by a magnet immersed in magnetic fluid. The expression for calculating the second-order buoyancy was derived, and a novel method for calculating and measuring the second-order buoyancy was proposed based on the expression. The second-order buoyancy was calculated by ANSYS and measured experimentally using the novel method. To verify the novel method, the second-order buoyancy was measured experimentally with a nonmagnetic rod stuck on the top surface of the magnet. The results of calculations and experiments show that the novel method for calculating the second-order buoyancy is correct with high accuracy. In addition, the main causes of error were studied in this paper, including magnetic shielding of magnetic fluid and the movement of magnetic fluid in a nonuniform magnetic field.
Second-order many-body perturbation study of solid hydrogen fluoride under pressure.
Sode, Olaseni; Hirata, So
2012-06-07
A linear-scaling, embedded-fragment, second-order many-body perturbation (MP2) method with basis sets up to aug-cc-pVTZ is applied to the antiparallel structure of solid hydrogen fluoride and deuterium fluoride under 0-20 GPa of ambient pressure. The optimized structures, including the lattice parameters and molar volume, and phonon dispersion as well as phonon density of states (DOS), are determined as a function of pressure. The basis-set superposition errors are removed by the counterpoise correction. The structural parameters at 0 GPa calculated by MP2 agree accurately with the observed, making the predicted values at higher pressures a useful pilot for future experiments. The corresponding values obtained by the Hartree-Fock method have large, systematic errors. The MP2/aug-cc-pVDZ frequencies of the infrared- and Raman-active vibrations of the three-dimensional solids are in good agreement with the observed and also justify previous vibrational analyses based on one-dimensional chain models; the non-coincidence of the infrared and Raman mode pairs can be explained as factor-group (Davydov) splitting. The exceptions are one pair of modes in the librational region, for which band assignments based on a one-dimensional chain model need to be revised, as well as the five pseudo-translational modes that exist only in a three-dimensional treatment. The observed pressure dependence of Raman bands in the stretching region, which red-shift with pressure, is accounted for by theory only qualitatively, while that in the pseudo-translational region is reproduced with quantitative accuracy. The present calculation proves to be limited in explaining the complex pressure dependence of the librational modes. The hydrogen-amplitude-weighted phonon DOS at 0 GPa is much less structured than the DOS obtained from one-dimensional models and may be more realistic in view of the also broad, structureless observed inelastic neutron scattering spectra. All major observed peaks can be
Second-order closure PBL model with new third-order moments: Comparison with LES data
Canuto, V. M.; Minotti, F.; Ronchi, C.; Ypma, R. M.; Zeman, O.
1994-01-01
This paper contains two parts. In the first part, a new set of diagnostic equations is derived for the third-order moments for a buoyancy-driven flow, by exact inversion of the prognostic equations for the third-order moment equations in the stationary case. The third-order moments exhibit a universal structure: they all are a linear combination of the derivatives of all the second-order moments, bar-w(exp 2), bar-w theta, bar-theta(exp 2), and bar-q(exp 2). Each term of the sum contains a turbulent diffusivity D(sub t), which also exhibits a universal structure of the form D(sub t) = a nu(sub t) + b bar-w theta. Since the sign of the convective flux changes depending on stable or unstable stratification, D(sub t) varies according to the type of stratification. Here nu(sub t) approximately equal to wl (l is a mixing length and w is an rms velocity) represents the 'mechanical' part, while the 'buoyancy' part is represented by the convective flux bar-w theta. The quantities a and b are functions of the variable N(sub tau)(exp 2), where N(exp 2) = g alpha derivative of Theta with respect to z and tau is the turbulence time scale. The new expressions for the third-order moments generalize those of Zeman and Lumley, which were subsequently adopted by Sun and Ogura, Chen and Cotton, and Finger and Schmidt in their treatments of the convective boundary layer. In the second part, the new expressions for the third-order moments are used to solve the ensemble average equations describing a purely convective boundary laye r heated from below at a constant rate. The computed second- and third-order moments are then compared with the corresponding Large Eddy Simulation (LES) results, most of which are obtained by running a new LES code, and part of which are taken from published results. The ensemble average results compare favorably with the LES data.
Second-order Born effects in the coplanar to perpendicular plane single ionization of Xe (5p)
International Nuclear Information System (INIS)
Singh, Prithvi; Purohit, G; Patidar, Vinod
2013-01-01
Differential cross section results for the coplanar to perpendicular plane ionization of xenon atoms at incident electron energies of 40 and 20 eV above ionization potential are reported. The cross sections have been calculated in the modified distorted wave Born approximation (DWBA) formalism including the second-order Born amplitude. Our present attempt verifies the role of second-order processes in the ionization of xenon atoms at low and intermediate energy ranges. We compare the (e, 2e) triple differential cross section results of our calculation with the very recent measurements of Nixon and Murray (2012 Phys. Rev. A 85 022716) and relativistic DWBA-G results of Illarionov and Stauffer (2012 J. Phys. B: At. Mol. Opt. Phys. 45 225202). Overall agreement with measurements has been improved by inclusion of a second-order term in the description of the collision process. (paper)
Directory of Open Access Journals (Sweden)
M. T. Abuelma'atti
2011-06-01
Full Text Available In this paper, the design of a universal second-order filter using configurable analog blocks (CABs for field programmable analog arrays is presented. The configurable blocks are capable of performing integration, differentiation, amplification, log, anti-log, add and negate functions. To maintain high frequency operation, the programmability and configurability of the blocks are achieved by digitally modifying the block's biasing conditions. Using at most four CABs, this article shows that it is possible to design a versatile second-order filter realizing all the standard five filter functions; lowpass, highpass, bandpass, notch and allpass. SPICE simulation results using practical bipolar junction transistor (BJT parameters confirm the feasibility of using the CABs in designing second-order filters.
Directory of Open Access Journals (Sweden)
Miao Yu
2017-01-01
Full Text Available This paper is devoted to the study of exponential synchronization problem for second-order nodes in dynamical network with time-varying communication delays and switching communication topologies. Firstly, a decomposition approach is employed to incorporate the nodes’ inertial effects into the distributed control design. Secondly, the sufficient conditions are provided to guarantee the exponential synchronization of second-order nodes in the case that the information transmission is delayed and the communication topology is balanced and arbitrarily switched. Finally, to demonstrate the effectiveness of the proposed theoretical results, it is applied to the typical second-order nodes in dynamical network, as a case study. Simulation results indicate that the proposed method has a high performance in synchronization of such network.
Boscheri, Walter; Dumbser, Michael; Loubère, Raphaël; Maire, Pierre-Henri
2018-04-01
In this paper we develop a conservative cell-centered Lagrangian finite volume scheme for the solution of the hydrodynamics equations on unstructured multidimensional grids. The method is derived from the Eucclhyd scheme discussed in [47,43,45]. It is second-order accurate in space and is combined with the a posteriori Multidimensional Optimal Order Detection (MOOD) limiting strategy to ensure robustness and stability at shock waves. Second-order of accuracy in time is achieved via the ADER (Arbitrary high order schemes using DERivatives) approach. A large set of numerical test cases is proposed to assess the ability of the method to achieve effective second order of accuracy on smooth flows, maintaining an essentially non-oscillatory behavior on discontinuous profiles, general robustness ensuring physical admissibility of the numerical solution, and precision where appropriate.
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Hae-Gwang Jeong
2013-01-01
Full Text Available This paper proposes a second-order harmonic reduction technique using a proportional-resonant (PR controller for a photovoltaic (PV power conditioning system (PCS. In a grid-connected single-phase system, inverters create a second-order harmonic at twice the fundamental frequency. A ripple component unsettles the operating points of the PV array and deteriorates the operation of the maximum power point tracking (MPPT technique. The second-order harmonic component in PV PCS is analyzed using an equivalent circuit of the DC/DC converter and the DC/AC inverter. A new feed-forward compensation technique using a PR controller for ripple reduction is proposed. The proposed algorithm is advantageous in that additional devices are not required and complex calculations are unnecessary. Therefore, this method is cost-effective and simple to implement. The proposed feed-forward compensation technique is verified by simulation and experimental results.
International Nuclear Information System (INIS)
Cao Jie; Wu Zhi-Hai; Peng Li
2016-01-01
This paper investigates the consensus tracking problems of second-order multi-agent systems with a virtual leader via event-triggered control. A novel distributed event-triggered transmission scheme is proposed, which is intermittently examined at constant sampling instants. Only partial neighbor information and local measurements are required for event detection. Then the corresponding event-triggered consensus tracking protocol is presented to guarantee second-order multi-agent systems to achieve consensus tracking. Numerical simulations are given to illustrate the effectiveness of the proposed strategy. (paper)
Directory of Open Access Journals (Sweden)
Diem Dang Huan
2015-12-01
Full Text Available The current paper is concerned with the controllability of nonlocal second-order impulsive neutral stochastic functional integro-differential equations with infinite delay and Poisson jumps in Hilbert spaces. Using the theory of a strongly continuous cosine family of bounded linear operators, stochastic analysis theory and with the help of the Banach fixed point theorem, we derive a new set of sufficient conditions for the controllability of nonlocal second-order impulsive neutral stochastic functional integro-differential equations with infinite delay and Poisson jumps. Finally, an application to the stochastic nonlinear wave equation with infinite delay and Poisson jumps is given.
Second-order interference in collisions of 4-MeV/u F9+ ions with H2
Misra, Deepankar; Kelkar, Aditya H.; Chatterjee, Shyamal; Tribedi, Lokesh C.
2009-12-01
Frequency doubling in interference oscillations in fast-ion-induced electron emission spectrum from H2 is investigated. Experimentally observed oscillatory structure is well explained by a model calculation based on the rescattering of emitted electron from the second H center. The second-order contribution is found to be as large as 10%. The doubling of oscillation frequency is found out to be independent of angle of observation. Derived analytical expression for the double differential cross section ratio including the first- and second-order interference terms, fits the observed oscillatory structure quite well. The present analysis is in broad agreement with the earlier observations by Stolterfoht
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Fuyong Wang
2017-01-01
Full Text Available This paper considers the containment control problem of second-order multiagent systems in the presence of time-varying delays and uncertainties with dynamically switching communication topologies. Moreover, the control algorithm is proposed for containment control, and the stability of the proposed containment control algorithm is studied with the aid of Lyapunov-Krasovskii function when the communication topology is jointly connected. Some sufficient conditions in terms of linear matrix inequalities (LMIs are provided for second-order containment control with multiple stationary leaders. Finally, simulations are given to verify the effectiveness of the obtained theoretical results.
Update on the Comparison of Second-Order Loads on a Tension Leg Platform for Wind Turbines: Preprint
Energy Technology Data Exchange (ETDEWEB)
Gueydon, Sebastien; Jonkman, Jason
2016-08-01
In comparison to other kinds of floaters (like a spar or a semisubmersible), the tension leg platform has several notable advantages: its vertical motions are negligible, its weight is lighter, and its mooring system's footprint is smaller. Although a tension leg platform has a negligible response to first-order vertical wave loads, the second-order wave loads need to be addressed. This paper follows up on a verification study of second-order wave loads on a tension leg platform for wind turbines done by the Maritime Research Institute of The Netherlands and National Renewable Energy Laboratory and it brings some corrections to its conclusions.
DEFF Research Database (Denmark)
Zhou, Bo; Ai, Xiaomeng; Fang, Jiakun
2017-01-01
(MISOCP) for the hybrid AC-DC power systems is proposed. The second order cone (SOC) relaxation is adopted to transform the AC and DC power flow constraints to MISOCP. Several IEEE test systems are used to validate the proposed MISCOP formulation of the optimal power flow (OPF) and unit commitment (UC......With the rapid development and deployment of voltage source converter (VSC) based HVDC, the traditional power system is evolving to the hybrid AC-DC grid. New optimization methods are urgently needed for these hybrid AC-DC power systems. In this paper, mixed-integer second order cone programming......) in the hybrid AC-DC power systems....
Blasche, P. R.
1980-01-01
Specific configurations of first and second order all digital phase locked loops are analyzed for both ideal and additive white gaussian noise inputs. In addition, a design for a hardware digital phase locked loop capable of either first or second order operation is presented along with appropriate experimental data obtained from testing of the hardware loop. All parameters chosen for the analysis and the design of the digital phase locked loop are consistent with an application to an Omega navigation receiver although neither the analysis nor the design are limited to this application.
Second-order optical nonlinearities in dilute melt proton exchange waveguides in z-cut LiNbO3
DEFF Research Database (Denmark)
Veng, Torben Erik; Skettrup, Torben; Pedersen, Kjeld
1996-01-01
Planar optical waveguides with different refractive indices are made in z-cut LiNbO3 with a dilute proton exchange method using a system of glycerol containing KHSO4 and lithium benzoate. The optical second-order susceptibilities of these waveguides are measured by detecting the 266 nm reflected...... second-harmonic signal generated by a 532 nm beam directed onto the waveguide surface. It is found for this kind of waveguides that in the waveguide region all the second-order susceptibilities take values of at least 90% of the original LiNbO; values for refractive index changes less than similar to 0...
Improving Measurement Precision of Hierarchical Latent Traits Using Adaptive Testing
Wang, Chun
2014-01-01
Many latent traits in social sciences display a hierarchical structure, such as intelligence, cognitive ability, or personality. Usually a second-order factor is linearly related to a group of first-order factors (also called domain abilities in cognitive ability measures), and the first-order factors directly govern the actual item responses.…
DEFF Research Database (Denmark)
Karlstrom, O.; Emary, C.; Zedler, P.
2013-01-01
We investigate the second-order von Neumann approach from a diagrammatic point of view and demonstrate its equivalence with the resonant tunneling approximation. The investigation of higher order diagrams shows that the method correctly reproduces the equation of motion for the single...
Kester, Kevin; Cremin, Hilary
2017-01-01
Peace and conflict studies (PACS) education has grown significantly in the last 30 years, mainly in Higher Education. This article critically analyzes the ways in which this field might be subject to poststructural critique, and posits Bourdieusian second-order reflexivity as a means of responding to these critiques. We propose here that…
Buratti, Sandra; Allwood, Carl Martin; Kleitman, Sabina
2013-01-01
In learning contexts, people need to make realistic confidence judgments about their memory performance. The present study investigated whether second-order judgments of first-order confidence judgments could help people improve their confidence judgments of semantic memory information. Furthermore, we assessed whether different personality and…
Xu, Lihua; Wubbena, Zane; Stewart, Trae
2016-01-01
Purpose: The purpose of this paper is to investigate the factor structure and the measurement invariance of the Multifactor Leadership Questionnaire (MLQ) across gender of K-12 school principals (n=6,317) in the USA. Design/methodology/approach: Nine first-order factor models and four second-order factor models were tested using confirmatory…
Schoondorp, Monique Annette
1992-01-01
This thesis describes the structure and second order nonlinear optical behaviour of several Langmuir-Blodgett films. Langmuir-Blodgett (LB) films are ultra thin films produced by the Langmuir-Blodgett technique, named after their inventors (Irving Langmuir and Katharina Blodgett).
Andrews, Benjamin James
2011-01-01
The equity properties can be used to assess the quality of an equating. The degree to which expected scores conditional on ability are similar between test forms is referred to as first-order equity. Second-order equity is the degree to which conditional standard errors of measurement are similar between test forms after equating. The purpose of…
DEFF Research Database (Denmark)
Abildskov, Jens; Constantinou, Leonidas; Gani, Rafiqul
1996-01-01
do not provide all the important molecular structural information. Therefore, addition of second-order terms, which provide the needed extra molecular structural information, is proposed. The scope of the new approach is demonstrated through the well-known UNIFAC model in terms of improved...
Directory of Open Access Journals (Sweden)
Xiao-Hua Zhang
2012-08-01
Full Text Available The effectiveness of traditional Chinese medicine (TCM against various diseases urges more low cost, speed and sensitive analytical methods for investigating the phamacology of TCM and providing a theoretical basis for clinical use. The potential of second-order calibration method was validated for the quantification of two effective ingredients of Schisandra chinensis in human plasma using spectrofluorimetry. The results obtained in the present study demonstrate the advantages of this strategy for multi-target determination in complex matrices. Although the spectra of the analytes are similar and a large number of interferences also exist, second-order calibration method could predict the accurate concentrations together with reasonable resolution of spectral profiles for analytes of interest owing to its âsecond-order advantageâ. Moreover, the method presented in this work allows one to simply experimental procedure as well as reduces the use of harmful chemical solvents. Keywords: Traditional Chinese medicine, Second-order calibration, Schizandrol A, Schizandrin B, Self-weighted alternating normalized residue fitting (SWANRF algorithm, Alternating normalization-weighted error (ANWE algorithm.
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Lv Xuezhe
2010-01-01
Full Text Available Abstract The existence and uniqueness of positive solution is obtained for the singular second-order -point boundary value problem for , , , where , , are constants, and can have singularities for and/or and for . The main tool is the perturbation technique and Schauder fixed point theorem.
Schoondorp, Monique Annette
1992-01-01
This thesis describes the structure and second order nonlinear optical behaviour of several Langmuir-Blodgett films. Langmuir-Blodgett (LB) films are ultra thin films produced by the Langmuir-Blodgett technique, named after their inventors (Irving Langmuir and Katharina Blodgett).
Directory of Open Access Journals (Sweden)
S. Marshal Anthoni
2004-01-01
Full Text Available We study the existence of mild solutions of the nonlinear second-order neutral functional differential and integrodifferential inclusions with nonlocal conditions in Banach spaces. The results are obtained by using the theory of strongly continuous cosine families of bounded linear operators and a fixed point theorem for condensing maps due to Martelli.
DEFF Research Database (Denmark)
Öhman, Filip; Mørk, Jesper; Tromborg, Bjarne
2007-01-01
We have developed a second-order small-signal model for describing the nonlinear redistribution of noise in a saturated semiconductor optical amplifier. In this paper, the details of the model are presented. A numerical example is used to compare the model to statistical simulations. We show that...
Directory of Open Access Journals (Sweden)
Wang Li
2008-01-01
Full Text Available We investigate the existence of almost-periodic weak solutions of second-order neutral delay-differential equations with piecewise constant argument of the form , where denotes the greatest integer function, is a real nonzero constant, and is almost periodic.
DEFF Research Database (Denmark)
Zhou, Bo; Ai, Xiaomeng; Fang, Jiakun
2017-01-01
With the rapid development and deployment of voltage source converter (VSC) based HVDC, the traditional power system is evolving to the hybrid AC-DC grid. New optimization methods are urgently needed for these hybrid AC-DC power systems. In this paper, mixed-integer second order cone programming ...
Directory of Open Access Journals (Sweden)
Daxiong Piao
2014-08-01
Full Text Available In this paper, using the Fourier series expansion and fixed point methods, we investigate the existence and uniqueness of Besicovitch almost periodic solutions for a class of second order differential equations involving reflection of the argument. Lipschitz nonlinear case is considered.
Directory of Open Access Journals (Sweden)
Wen-Zhen Gong
2012-01-01
Full Text Available By using minimax methods in critical point theory, a new existence theorem of infinitely many periodic solutions is obtained for a class of second-order p-Laplacian systems with impulsive effects. Our result generalizes many known works in the literature.
Angel, Jordan B.; Banks, Jeffrey W.; Henshaw, William D.
2018-01-01
High-order accurate upwind approximations for the wave equation in second-order form on overlapping grids are developed. Although upwind schemes are well established for first-order hyperbolic systems, it was only recently shown by Banks and Henshaw [1] how upwinding could be incorporated into the second-order form of the wave equation. This new upwind approach is extended here to solve the time-domain Maxwell's equations in second-order form; schemes of arbitrary order of accuracy are formulated for general curvilinear grids. Taylor time-stepping is used to develop single-step space-time schemes, and the upwind dissipation is incorporated by embedding the exact solution of a local Riemann problem into the discretization. Second-order and fourth-order accurate schemes are implemented for problems in two and three space dimensions, and overlapping grids are used to treat complex geometry and problems with multiple materials. Stability analysis of the upwind-scheme on overlapping grids is performed using normal mode theory. The stability analysis and computations confirm that the upwind scheme remains stable on overlapping grids, including the difficult case of thin boundary grids when the traditional non-dissipative scheme becomes unstable. The accuracy properties of the scheme are carefully evaluated on a series of classical scattering problems for both perfect conductors and dielectric materials in two and three space dimensions. The upwind scheme is shown to be robust and provide high-order accuracy.
Energy Technology Data Exchange (ETDEWEB)
Moreno y M, A. [Departamento de Apoyo en Ciencias Aplicadas, Benemerita Universidad Autonoma de Puebla, Sur 104 Col. Centro, 72000 Puebla (Mexico); Moreno B, A. [Facultad de Quimica, Ciudad Universitaria, UNAM, 04510 Mexico D.F. (Mexico)
1999-07-01
In this work it is described the Randall and Wilkins second order kinetics in Microsoft Excel language, which allows its expression as the sum of Gaussian and the correction factors corresponding. These factors are obtained of the differences between the real thermoluminescent curve and the Gaussian proposed. The results obtained justify the Gaussian expression added to the correction factor. (Author)
Alessandri, Guido; Perinelli, Enrico; De Longis, Evelina; Theodorou, Annalisa
2018-01-01
In recent years, research in organizational psychology has witnessed a shift in attention from a mostly variable-focused approach, to a mostly person-focused approach. Indeed, it has been widely recognized that the study of worker's heterogeneity is a meaningful and necessary task of researchers dealing with human behavior in organizational contexts. As a consequence, there has been growing interest in the application of statistical analyses able to uncover latent sub-groups of workers. The present contribution was conceived as a tutorial for the application of one of these statistical analyses, namely second-order growth mixture modeling, and to illustrate its inner links with concepts from non-linear dynamic models. Throughout the paper, we provided (a) a discussion on the relationships between growth mixture modeling and the cusp catastrophe model; (b) Mplus syntaxes and output excerpts of a longitudinal analysis conducted on job performance (N = 420 employees rated once a year for four consecutive years); (c) an overview of two important topics regarding the correct implementation of growth mixture modeling (i.e., optimal number of classes and local maxima).
DEFF Research Database (Denmark)
Ernstsen, Verner Brandbyge; Lefebvre, Alice; Kroon, Aart
2013-01-01
A detailed digital elevation model (DEM) of an intertidal sand flat in the Knudedyb tidal inlet in the Danish Wadden Sea, derived from high-resolution Light Detection And Ranging (LiDAR) data, reveals a large elongated bedform field with complex bedform morphologies and drainage channel networks....... This indicates distinct second-order sand transport pathways oblique to the main tidal transport pathways. A conceptual model for the development of the bedforms and channels is presented, which comprises hypotheses of the hydrodynamic forcing of the different second-order sand transport pathways. During flood...... tide, sand is transported along ESE-oriented pathways across the intertidal flat towards the inner tidal basin. During the late stages of ebb tide, sand is transported in drainage channels (WSWoriented) from the intertidal flat towards the inlet channel. During storm events with winds from SW, wave...
International Nuclear Information System (INIS)
Liang Xiaorui; Zhang Yong; Liang Chenghong; Li Yin; Zhao Bo
2011-01-01
The objective of this investigation was to design a series of coumarin with various substituents which show high nonlinear optical activity. The full geometry optimisations of designed coumarin systems were performed using Density Functional Theory (DFT) method at B3LYP/6-31G level of theory. The calculations of the static second-order NLO polarizabilities (β) of these systems were performed at the same level of theory. Combined with time-dependent density-functional theory (TD-DFT), the molecular electric spectrum was calculated. The results indicate that this series of coumarin have high β values. And series A have better planarity, longer conjugated bridge and larger β tot value than series B. The energy transition of frontier molecular orbitals is the key factor to the second-order NLO response. (authors)
International Nuclear Information System (INIS)
Supriyono; Miyoshi, T.
1997-01-01
NECD Method and runge-Kutta method for large system of second order ordinary differential equations in comparing algorithm. The paper introduce a extrapolation method used for solving the large system of second order ordinary differential equation. We call this method the modified extrapolated central difference (MECD) method. for the accuracy and efficiency MECD method. we compare the method with 4-th order runge-Kutta method. The comparison results show that, this method has almost the same accuracy as the 4-th order runge-Kutta method, but the computation time is about half of runge-Kutta. The MECD was declare by the author and Tetsuhiko Miyoshi of the Dept. Applied Science Yamaguchi University Japan
Second-order small disturbance theory for hypersonic flow over power-law bodies. Ph.D. Thesis
Townsend, J. C.
1974-01-01
A mathematical method for determining the flow field about power-law bodies in hypersonic flow conditions is developed. The second-order solutions, which reflect the effects of the second-order terms in the equations, are obtained by applying the method of small perturbations in terms of body slenderness parameter to the zeroth-order solutions. The method is applied by writing each flow variable as the sum of a zeroth-order and a perturbation function, each multiplied by the axial variable raised to a power. The similarity solutions are developed for infinite Mach number. All results obtained are for no flow through the body surface (as a boundary condition), but the derivation indicates that small amounts of blowing or suction through the wall can be accommodated.
An, Hong-Lin; Arriola, Alexander; Gross, Simon; Fuerbach, Alexander; Withford, Michael J.; Fleming, Simon
2014-01-01
The thermal poling technique was applied to optical waveguides embedded in a commercial boro-aluminosilicate glass, resulting in high levels of induced second-order optical nonlinearity. The waveguides were fabricated using the femtosecond laser direct-write technique, and thermally poled samples were characterized with second harmonic optical microscopy to reveal the distribution profile of the induced nonlinearity. It was found that, in contrast to fused silica, the presence of waveguides in boro-aluminosilicate glass led to an enhancement of the creation of the second-order nonlinearity, which is larger in the laser written waveguiding regions when compared to the un-modified substrate. The magnitude of the nonlinear coefficient d33 achieved in the core of the laser-written waveguides, up to 0.2 pm/V, was comparable to that in thermally poled fused silica, enabling the realization of compact integrated electro-optic devices in boro-aluminosilicate glasses.
A New Fast Nonsingular Terminal Sliding Mode Control for a Class of Second-Order Uncertain Systems
Directory of Open Access Journals (Sweden)
Linjie Xin
2016-01-01
Full Text Available This paper considers the robust and adaptive nonsingular terminal sliding mode (NTSM control for a class of second-order uncertain systems. First, a new fast NTSM was proposed which had global fast convergence rate in the sliding phase. Then, a new form of robust NTSM controller was designed to handle a wider class of second-order uncertain systems. Moreover, an exponential-decline switching gain was introduced for chattering suppression. After that, a double sliding surfaces control scheme was constructed to combine the NTSM control with the adaptive technique. The benefit is that a strict demonstration can be given for the stagnation problem in the stability analysis of NTSM. Finally, a case study for tracking control of a variable-length pendulum was performed to verify the proposed controllers.
Katona, Thomas R; Isikbay, Serkis C; Chen, Jie
2014-03-01
To measure the effects of first- and second-order gable bends on the forces and moments produced by a commercially available closing T-loop archwire. A dentoform-simulated space closure case was mounted on an orthodontic force tester. Sixteen gable bend combinations were placed in the archwires, which were then activated using standard clinical procedures. At each activation, the three force components and three moment components on the maxillary left lateral incisor and canine were simultaneously measured. The first- and second-order gable bends showed low load coupling effects when used independently, but the load systems became unpredictable when bends were combined. Gable bends affect the magnitudes and directions of the forces and moments that are applied to teeth. The resulting moment to force ratios are sensitive to the bends. Gable bends alter the orthodontic load systems; however, the three-dimensional interactions produce complex and unpredictable tradeoffs.
Energy Technology Data Exchange (ETDEWEB)
Bodrog, Zoltan; Aradi, Balint [Bremen Center for Computational Materials Science, University of Bremen (Germany)
2012-02-15
Improving the precision of self-consistent-charges density-functional tight-binding method (SCC-DFTB) without losing its computational efficiency is primarily thought and hoped to be possible, if possible at all, by moving beyond its current two-centre-approximative tight-binding structure and the second-order nature of SCC. In this paper, however, we point out that there may still be possibilities of making it more precise without such an extension. Two improvements within the very second-order SCC are proposed here. First, inclusion of a multipole expansion of interacting atomic charge fluctuations, and second, a semi-empirical refinement of their interaction potential profiles and their self-interaction energies. Besides showing in detail what is to be improved with respect to the current SCC-DFTB realizations, we fully derive the respective new formulas ready to implement. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
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Hongchang Sun
2018-01-01
Full Text Available This paper proposes an adaptive gain second-order sliding mode control strategy to track optimal electromagnetic torque and regulate reactive power of doubly fed wind turbine system. Firstly, wind turbine aerodynamic characteristics and doubly fed induction generator (DFIG modeling are presented. Then, electromagnetic torque error and reactive power error are chosen as sliding variables, and fixed gain super-twisting sliding mode control scheme is designed. Considering that uncertainty upper bound is unknown and is hard to be estimated in actual doubly fed wind turbine system, a gain scheduled law is proposed to compel control parameters variation according to uncertainty upper bound real-time. Adaptive gain second-order sliding mode rotor voltage control method is constructed in detail and finite time stability of doubly fed wind turbine control system is strictly proved. The superiority and robustness of the proposed control scheme are finally evaluated on a 1.5 MW DFIG wind turbine system.
Nakagawa, Ryo; Kyoya, Haruki; Shimizu, Hiroshi; Kihara, Takashi; Hashimoto, Ken-ya
2015-07-01
In this study, we examine the generation mechanisms of the second-order nonlinear signals in surface acoustic wave resonators/duplexers fabricated on a 42°YX-LiTaO3 substrate. It is shown that the crystal asymmetry of the substrate can generate the second-order nonlinear signals. The following two mechanisms mainly contribute to their generation: (a) self-mixing of the electrostatic field and (b) mixing of the electrostatic field with the strain field associated with laterally propagating modes. Both of them occur at the gaps between the electrode tip and the dummy electrode. In addition, an interdigital transducer design that cancels this asymmetry is proposed. The design is applied to a one-port resonator and a duplexer, and the effectiveness of this technique is demonstrated.
Energy Technology Data Exchange (ETDEWEB)
Polo L, M. A.; Espinosa P, G. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)], e-mail: gepe@xanum.uam.mx
2009-10-15
In this work is presented the deduction and solution of punctual equation of neutronic kinetics of second order, which is obtained applying the fundamental principles of nuclear reactor physics. The work hypothesis consisted on considering that the temporary dependence of current vector is not worthless in the constitutive law for the approach of neutronic processes with the diffusion equation. As results of work eight roots of analytical solution of punctual equation of neutronic kinetics of second order are obtained for case of six groups of slowed neutrons, a root more respect the classic pattern of punctual equation of neutronic kinetics. This theory can be used when appear highly heterogeneous configurations in the nuclear reactor. (Author)
Energy Technology Data Exchange (ETDEWEB)
Lin Liu (Pro-Reitoria de Pesquisa, Univ. Estadual de Campinas, SP (Brazil) Lab. Nacional de Luz Sincrotron-LNLS, Campinas, SP (Brazil)); Concalves da Silva, C.E.T. (Inst. de Fisica Gleb Wataghin, Univ. Estadual de Campinas, SP (Brazil) Lab. Nacional de Luz Sincrotron-LNLS, Campinas, SP (Brazil))
1993-05-15
We analyze the second order single particle longitudinal dynamics in a quasi-isochronous storage ring. We expand the momentum compaction factor to include the effects of second order terms taking sextupoles into account and of transverse betatron oscillations. The introduction of nonlinearities due to higher order terms results in a second stability region for longitudinal phase oscillations, in addition to the well known linear stable operation point. The conditions for this new solution to fall within the energy acceptance of the storage ring are presented. Inclusion of transverse motion coupling may lead to either a reduction or an enhancement of the stable longitudinal phase-space regions. The analysis is applied to the LNLS 1.15 GeV UVX electron storage ring, indicating that it should be possible to operate this ring in a quasi-isochronous mode. (orig.).
Boltz, F. W.
1984-01-01
An algorithm is presented for efficient p-iterative solution of the Lambert/Gauss orbit-determination problem using second-order Newton iteration. The algorithm is based on a universal transformation of Kepler's time-of-flight equation and approximate inverse solutions of this equation for short-way and long-way flight paths. The approximate solutions provide both good starting values for iteration and simplified computation of the second-order term in the iteration formula. Numerical results are presented which indicate that in many cases of practical significance (except those having collinear position vectors) the algorithm produces at least eight significant digits of accuracy with just two or three steps of iteration.
DUCASSE , Eric; YAACOUBI , Slah
2010-01-01
International audience; A tensor Hankel transform'' (THT) is defined for vector fields, such as displacement, and second-order tensor fields, such as stress or strain. The THT establishes a bijection between the real space and the wave-vector domain, and, remarkably, cannot be reduced to a scalar transform applied separately to each component. One of the advantages of this approach is that some standard elasticity problems can be concisely rewritten by applying this tensor integral transform ...
Dynamical Study of a Second Order DPCM Transmission System Modeled by a Piece-Wise Linear Function
Taralova, Ina; Fournier-Prunaret, D.
2009-01-01
17 pages; International audience; This paper analyses the behaviour of a second order DPCM (Differential Pulse Code Modulation) transmission system when the nonlinear characteristic of the quantizer is taken into consideration. In this way, qualitatively new properties of the DPCM system have been unravelled, which cannot be observed and explained if the nonlinearity of the quantizer is neglected. For the purposes of this study, a piece-wise linear nondifferentiable quantizer characteristic i...
Ngwane, F. F.; Jator, S. N.
2017-01-01
In this paper, we present a block hybrid trigonometrically fitted Runge-Kutta-Nyström method (BHTRKNM), whose coefficients are functions of the frequency and the step-size for directly solving general second-order initial value problems (IVPs), including Hamiltonian systems such as the energy conserving equations and systems arising from the semidiscretization of partial differential equations (PDEs). Four discrete hybrid formulas used to formulate the BHTRKNM are provided by a continuous one...
Directory of Open Access Journals (Sweden)
You Zheng
2015-01-01
Full Text Available An adaptive second-order sliding mode controller is proposed for a class of nonlinear systems with unknown input. The proposed controller continuously drives the sliding variable and its time derivative to zero in the presence of disturbances with unknown boundaries. A Lyapunov approach is used to show finite time stability for the system in the presence of a class of uncertainty. An illustrative simulation example is presented to demonstrate the performance and robustness of the proposed controller.
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Zhang Peiguo
2011-01-01
Full Text Available Abstract By obtaining intervals of the parameter λ, this article investigates the existence of a positive solution for a class of nonlinear boundary value problems of second-order differential equations with integral boundary conditions in abstract spaces. The arguments are based upon a specially constructed cone and the fixed point theory in cone for a strict set contraction operator. MSC: 34B15; 34B16.
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Joao Fialho
2017-02-01
Full Text Available This paper is concerned with the existence of bounded or unbounded solutions to regular and singular second order boundary value problem on the half-line with functional boundary conditions. These functional boundary conditions generalize the usual boundary assumptions and may be applied to a broad number of cases, such as, nonlocal, integro-differential, with delays, with maximum or minimum arguments... The arguments are based on the Schauder fixed point theorem and lower and upper solutions method.
Selvamony, Subash Chandra Bose
2013-01-01
This literature compares the performance of second order competitive consecutive reaction in Fed-Batch Reactor with that in continuous Plug Flow Reactor. In a kinetic sense, this simulation study aims to develop a case for continuous Plug Flow Reactor in pharmaceutical, fine chemical, and related other chemical industries. MATLAB is used to find solutions for the differential equations. The simulation results show that, for certain cases of nonelementary scenario, product selectivity is highe...
Burtyka, Filipp
2018-01-01
The paper considers algorithms for finding diagonalizable and non-diagonalizable roots (so called solvents) of monic arbitrary unilateral second-order matrix polynomial over prime finite field. These algorithms are based on polynomial matrices (lambda-matrices). This is an extension of existing general methods for computing solvents of matrix polynomials over field of complex numbers. We analyze how techniques for complex numbers can be adapted for finite field and estimate asymptotic complexity of the obtained algorithms.
International Nuclear Information System (INIS)
Culzoni, Maria J.; Goicoechea, Hector C.; Ibanez, Gabriela A.; Lozano, Valeria A.; Marsili, Nilda R.; Olivieri, Alejandro C.; Pagani, Ariana P.
2008-01-01
Multivariate curve resolution coupled to alternating least-squares (MCR-ALS) has been employed to model kinetic-spectroscopic second-order data, with focus on the achievement of the important second-order advantage, under conditions of extreme spectral overlapping among sample components. A series of simulated examples shows that MCR-ALS can conveniently handle the studied analytical problem unlike other second-order multivariate calibration algorithms, provided matrix augmentation is implemented in the spectral mode instead of in the usual kinetic mode. The approach has also been applied to three experimental examples, which involve the determination of: (1) the antiparkinsonian carbidopa (analyte) in the presence of levodopa as a potential interferent, both reacting with cerium (IV) to produce the fluorescent species cerium (III) with different kinetics; (2) Fe(II) (analyte) in the presence of the interferent Zn(II), both catalyzing the oxidation of methyl orange with potassium bromate; and (3) tartrazine (analyte) in the presence of the interferent brilliant blue, both oxidized with potassium bromate, with the interferent leading to a product with an absorption spectrum very similar to tartrazine. The results indicate good analytical performance towards the analytes, despite the intense spectral overlapping and the presence of unexpected constituents in the test samples
Directory of Open Access Journals (Sweden)
Ismail Shahin
2010-01-01
Full Text Available Speaker identification performance is almost perfect in neutral talking environments. However, the performance is deteriorated significantly in shouted talking environments. This work is devoted to proposing, implementing, and evaluating new models called Second-Order Circular Suprasegmental Hidden Markov Models (CSPHMM2s to alleviate the deteriorated performance in the shouted talking environments. These proposed models possess the characteristics of both Circular Suprasegmental Hidden Markov Models (CSPHMMs and Second-Order Suprasegmental Hidden Markov Models (SPHMM2s. The results of this work show that CSPHMM2s outperform each of First-Order Left-to-Right Suprasegmental Hidden Markov Models (LTRSPHMM1s, Second-Order Left-to-Right Suprasegmental Hidden Markov Models (LTRSPHMM2s, and First-Order Circular Suprasegmental Hidden Markov Models (CSPHMM1s in the shouted talking environments. In such talking environments and using our collected speech database, average speaker identification performance based on LTRSPHMM1s, LTRSPHMM2s, CSPHMM1s, and CSPHMM2s is 74.6%, 78.4%, 78.7%, and 83.4%, respectively. Speaker identification performance obtained based on CSPHMM2s is close to that obtained based on subjective assessment by human listeners.
Sousa, Carmen; Domingo, Alex; de Graaf, Coen
2017-11-16
The second-order spin-orbit coupling is evaluated in two transition-metal complexes to establish the effect on the deactivation mechanism of the excited low-spin state in systems that undergo spin transitions under the influence of light. We compare the standard perturbational approach to calculate the second-order interaction with a variational strategy based on the effective Hamiltonian theory and show that the former one can only be applied in some special cases and even then gives results that largely overestimate the interaction. The combined effect of geometry distortions and second-order spin-orbit coupling leads to sizeable interactions for states that are nearly uncoupled in the symmetric (average) structure of the complex. This opens the possibility of a direct deactivation from the singlet and triplet states of the metal-to-ligand charge-transfer manifold to the final high-spin state as suggested from the interpretation of experimental data but so far not supported by theoretical descriptions of the light-induced spin crossover. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Pál eVakli
2014-06-01
Full Text Available The spatial distances among the features of a face are commonly referred to as second-order relations, and the coding of these properties is often regarded as a cornerstone in face recognition. Previous studies have provided mixed results regarding whether the N170, a face-sensitive component of the event-related potential, is sensitive to second-order relations. Here we investigated this issue in a gender discrimination paradigm following long-term (5 seconds adaptation to normal or vertically stretched male and female faces, considering that the latter manipulation substantially alters the position of the inner facial features. Gender-ambiguous faces were more likely judged to be female following adaptation to a male face and vice versa. This aftereffect was smaller but statistically significant after being adapted to vertically stretched when compared to unstretched adapters. Event-related potential recordings revealed that adaptation effects measured on the amplitude of the N170 show strong modulations by the second-order relations of the adapter: reduced N170 amplitude was observed, however, this reduction was smaller in magnitude after being adapted to stretched when compared to unstretched faces. These findings suggest early face-processing, as reflected in the N170 component, proceeds by extracting the spatial relations of inner facial features.
Energy Technology Data Exchange (ETDEWEB)
Grozdanov, Sašo [Instituut-Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, Leiden 2333 CA (Netherlands); Starinets, Andrei O. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)
2017-03-30
Gauss-Bonnet holographic fluid is a useful theoretical laboratory to study the effects of curvature-squared terms in the dual gravity action on transport coefficients, quasinormal spectra and the analytic structure of thermal correlators at strong coupling. To understand the behavior and possible pathologies of the Gauss-Bonnet fluid in 3+1 dimensions, we compute (analytically and non-perturbatively in the Gauss-Bonnet coupling) its second-order transport coefficients, the retarded two- and three-point correlation functions of the energy-momentum tensor in the hydrodynamic regime as well as the relevant quasinormal spectrum. The Haack-Yarom universal relation among the second-order transport coefficients is violated at second order in the Gauss-Bonnet coupling. In the zero-viscosity limit, the holographic fluid still produces entropy, while the momentum diffusion and the sound attenuation are suppressed at all orders in the hydrodynamic expansion. By adding higher-derivative electromagnetic field terms to the action, we also compute corrections to charge diffusion and identify the non-perturbative parameter regime in which the charge diffusion constant vanishes.
Tsang, Leung; Chan, Chi Hou; Kong, Jin AU; Joseph, James
1992-01-01
Complete polarimetric signatures of a canopy of dielectric cylinders overlying a homogeneous half space are studied with the first and second order solutions of the vector radiative transfer theory. The vector radiative transfer equations contain a general nondiagonal extinction matrix and a phase matrix. The energy conservation issue is addressed by calculating the elements of the extinction matrix and the elements of the phase matrix in a manner that is consistent with energy conservation. Two methods are used. In the first method, the surface fields and the internal fields of the dielectric cylinder are calculated by using the fields of an infinite cylinder. The phase matrix is calculated and the extinction matrix is calculated by summing the absorption and scattering to ensure energy conservation. In the second method, the method of moments is used to calculate the elements of the extinction and phase matrices. The Mueller matrix based on the first order and second order multiple scattering solutions of the vector radiative transfer equation are calculated. Results from the two methods are compared. The vector radiative transfer equations, combined with the solution based on method of moments, obey both energy conservation and reciprocity. The polarimetric signatures, copolarized and depolarized return, degree of polarization, and phase differences are studied as a function of the orientation, sizes, and dielectric properties of the cylinders. It is shown that second order scattering is generally important for vegetation canopy at C band and can be important at L band for some cases.
Energy Technology Data Exchange (ETDEWEB)
Culzoni, Maria J. [Laboratorio de Desarrollo Analitico y Quimiometria (LADAQ), Catedra de Quimica Analitica I, Facultad de Bioquimica y Ciencias Biologicas, Universidad Nacional del Litoral, Ciudad Universitaria, Santa Fe S3000ZAA (Argentina); Goicoechea, Hector C. [Laboratorio de Desarrollo Analitico y Quimiometria (LADAQ), Catedra de Quimica Analitica I, Facultad de Bioquimica y Ciencias Biologicas, Universidad Nacional del Litoral, Ciudad Universitaria, Santa Fe S3000ZAA (Argentina)], E-mail: hgoico@fbcb.unl.edu.ar; Ibanez, Gabriela A.; Lozano, Valeria A. [Departamento de Quimica Analitica, Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario and Instituto de Quimica Rosario (IQUIR-CONICET), Suipacha 531, Rosario S2002LRK (Argentina); Marsili, Nilda R. [Laboratorio de Desarrollo Analitico y Quimiometria (LADAQ), Catedra de Quimica Analitica I, Facultad de Bioquimica y Ciencias Biologicas, Universidad Nacional del Litoral, Ciudad Universitaria, Santa Fe S3000ZAA (Argentina); Olivieri, Alejandro C. [Departamento de Quimica Analitica, Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario and Instituto de Quimica Rosario (IQUIR-CONICET), Suipacha 531, Rosario S2002LRK (Argentina)], E-mail: aolivier@fbioyf.unr.edu.ar; Pagani, Ariana P. [Departamento de Quimica Analitica, Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario and Instituto de Quimica Rosario (IQUIR-CONICET), Suipacha 531, Rosario S2002LRK (Argentina)
2008-04-28
Multivariate curve resolution coupled to alternating least-squares (MCR-ALS) has been employed to model kinetic-spectroscopic second-order data, with focus on the achievement of the important second-order advantage, under conditions of extreme spectral overlapping among sample components. A series of simulated examples shows that MCR-ALS can conveniently handle the studied analytical problem unlike other second-order multivariate calibration algorithms, provided matrix augmentation is implemented in the spectral mode instead of in the usual kinetic mode. The approach has also been applied to three experimental examples, which involve the determination of: (1) the antiparkinsonian carbidopa (analyte) in the presence of levodopa as a potential interferent, both reacting with cerium (IV) to produce the fluorescent species cerium (III) with different kinetics; (2) Fe(II) (analyte) in the presence of the interferent Zn(II), both catalyzing the oxidation of methyl orange with potassium bromate; and (3) tartrazine (analyte) in the presence of the interferent brilliant blue, both oxidized with potassium bromate, with the interferent leading to a product with an absorption spectrum very similar to tartrazine. The results indicate good analytical performance towards the analytes, despite the intense spectral overlapping and the presence of unexpected constituents in the test samples.
On the second-order homogenization of wave motion in periodic media and the sound of a chessboard
Wautier, Antoine; Guzina, Bojan B.
2015-05-01
The goal of this study is to better understand the mathematical structure and ramifications of the second-order homogenization of low-frequency wave motion in periodic solids. To this end, multiple-scales asymptotic approach is applied to the scalar wave equation (describing anti-plane shear motion) in one and two spatial dimensions. In contrast to previous studies where the second-order homogenization has lead to the introduction of a single fourth-order derivative in the governing equation, present investigation demonstrates that such (asymptotic) approach results in a family of field equations uniting spatial, temporal, and mixed fourth-order derivatives - that jointly control incipient wave dispersion. Given the consequent freedom in selecting the affiliated lengthscale parameters, the notion of an optimal asymptotic model is next considered in a one-dimensional setting via its ability to capture the salient features of wave propagation within the first Brillouin zone, including the onset and magnitude of the phononic band gap. In the context of two-dimensional wave propagation, on the other hand, the asymptotic analysis is first established in a general setting, exposing the constant shear modulus as sufficient condition under which the second-order approximation of a bi-periodic elastic solid is both isotropic and limited to even-order derivatives. On adopting a chessboard-like periodic structure (with contrasts in both modulus and mass density) as a testbed for in-depth analytical treatment, it is next shown that the second-order approximation of germane wave motion is governed by a family fourth-order differential equations that: (i) entail exclusively even-order derivatives and homogenization coefficients that depend explicitly on the contrast in mass density; (ii) describe anisotropic wave dispersion characterized by the "sin4 θ +cos4 θ" term, and (iii) include the asymptotic model for a square lattice of circular inclusions as degenerate case. For
DEFF Research Database (Denmark)
Ulbæk, Ib
En tekstlingvistisk grundantagelse om tekster er, at de hænger sammen. De er kohærente. Nogle tekster er mere kohærente end andre, det er velkendt. Men internt i teksterne er der også grader af kohærens: nogle dele af teksten hænger bedre sam-men end andre. Dele af teksterne er inkohærente - uden...
DEFF Research Database (Denmark)
Ulbæk, Ib
2016-01-01
Begrebet kohærens er et stumpt instrument, når det kommer til beskrivelse og analyse af tekster. I traditionen fra Beugrande og Dressler (1981) betyder det vagt, at teksten er en helhed, hænger sammen. Van Dijk og Kintsch (1983) analyserede sammenhæng som referentiel identitet, en analyse som sen...
Stoeck, Christian T; von Deuster, Constantin; Fleischmann, Thea; Lipiski, Miriam; Cesarovic, Nikola; Kozerke, Sebastian
2018-04-01
To directly compare in vivo versus postmortem second-order motion-compensated spin-echo diffusion tensor imaging of the porcine heart. Second-order motion-compensated spin-echo cardiac diffusion tensor imaging was performed during systolic contraction in vivo and repeated upon cardiac arrest by bariumchloride without repositioning of the study animal or replaning of imaging slices. In vivo and postmortem reproducibility was assessed by repeat measurements. Comparison of helix, transverse, and sheet (E2A) angulation as well as mean diffusivity and fractional anisotropy was performed. Intraclass correlation coefficients for repeated measurements (postmortem/in vivo) were 0.95/0.96 for helix, 0.70/0.66 for transverse, and 0.79/0.72 for E2A angulation; 0.83/0.72 for mean diffusivity; and 0.78/0.76 for fractional anisotropy. The corresponding 95% levels of agreement across the left ventricle were: helix 14 to 18°/12 to 15°, transverse 9 to 10°/10 to 11°, E2A 15 to 20°/16 to 18°. The 95% levels of agreement across the left ventricle for the comparison of postmortem versus in vivo were 20 to 22° for helix, 13 to 19° for transverse, and 24 to 31° for E2A angulation. Parameters derived from in vivo second-order motion-compensated spin-echo diffusion tensor imaging agreed well with postmortem imaging, indicating sufficient suppression of motion-induced signal distortions of in vivo cardiac diffusion tensor imaging. Magn Reson Med 79:2265-2276, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
Energy Technology Data Exchange (ETDEWEB)
Favorite, Jeffrey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-11-30
The Second-Level Adjoint Sensitivity System (2nd-LASS) that yields the second-order sensitivities of a response of uncollided particles with respect to isotope densities, cross sections, and source emission rates is derived in Refs. 1 and 2. In Ref. 2, we solved problems for the uncollided leakage from a homogeneous sphere and a multiregion cylinder using the PARTISN multigroup discrete-ordinates code. In this memo, we derive solutions of the 2nd-LASS for the particular case when the response is a flux or partial current density computed at a single point on the boundary, and the inner products are computed using ray-tracing. Both the PARTISN approach and the ray-tracing approach are implemented in a computer code, SENSPG. The next section of this report presents the equations of the 1st- and 2nd-LASS for uncollided particles and the first- and second-order sensitivities that use the solutions of the 1st- and 2nd-LASS. Section III presents solutions of the 1st- and 2nd-LASS equations for the case of ray-tracing from a detector point. Section IV presents specific solutions of the 2nd-LASS and derives the ray-trace form of the inner products needed for second-order sensitivities. Numerical results for the total leakage from a homogeneous sphere are presented in Sec. V and for the leakage from one side of a two-region slab in Sec. VI. Section VII is a summary and conclusions.
International Nuclear Information System (INIS)
Elbakry, M.Y.; El-Helly, M.; Elbakry, M.Y.
2010-01-01
Neural networks are widely for solving many scientific linear and non-linear problems. In this work ,we used the artificial neural network (ANN) to simulate and predict the torque and force acting on the outer stationary sphere due to steady state motion of the second order fluid between two eccentric spheres by a rotating inner sphere with an angular velocity Ω. the (ANN) model has been trained based on the experimental data to produce the torque and force at different eccentricities. The experimental and trained torque and force are compared. The designed ANN shows a good match to the experimental data.
International Nuclear Information System (INIS)
Metawei, Z.
2000-01-01
We present the first and second - order corrections to the eikonal phase shifts for the interactions of two deformed nuclei. The elastic scattering differential cross-section has been calculated for both the interactions of I2 C- 12 C system (at energies 1016, 1449 and 2400 MeV) and 16 O- 12 C system (at energy 1503 MeV). The calculated results corrections seems to improve the agreement with the experimental data.The deflection function, the S-matrix,the near-side and the far-side decompositions of the scattering amplitude has been calculated using the same corrections
Tang, Chen; Han, Lin; Ren, Hongwei; Zhou, Dongjian; Chang, Yiming; Wang, Xiaohang; Cui, Xiaolong
2008-10-01
We derive the second-order oriented partial-differential equations (PDEs) for denoising in electronic-speckle-pattern interferometry fringe patterns from two points of view. The first is based on variational methods, and the second is based on controlling diffusion direction. Our oriented PDE models make the diffusion along only the fringe orientation. The main advantage of our filtering method, based on oriented PDE models, is that it is very easy to implement compared with the published filtering methods along the fringe orientation. We demonstrate the performance of our oriented PDE models via application to two computer-simulated and experimentally obtained speckle fringes and compare with related PDE models.
Sbierski, Björn; Karrasch, Christoph
2017-12-01
We devise a functional renormalization group treatment for a chain of interacting spinless fermions which is correct up to second order in interaction strength. We treat both inhomogeneous systems in real space as well as the translationally invariant case in a k -space formalism. The strengths and shortcomings of the different schemes as well as technical details of their implementation are discussed. We use the method to study two proof-of-principle problems in the realm of Luttinger liquid physics, namely, reflection at interfaces and power laws in the occupation number as a function of crystal momentum.
Growth and PhysioChemical Properties of Second-Order Nonlinear Optical L-Threonine Single Crystals
Directory of Open Access Journals (Sweden)
G. Ramesh Kumar
2009-01-01
Full Text Available The present aim of the paper is to grow and to study the various properties of L-threonine amino acid single crystal in various aspects. Crystal growth of L-threonine single crystals has been carried out with the help of crystallization kinetics. pH and deuteration effects on the properties of the grown crystals have been studied and the results presented in a lucid manner. The various second-order NLO parameters were evaluated using anharmonic oscillator model. Particle and ion irradiation effects on structural, optical, and surface properties of the crystals have also been studied in detail.
Fonda, Alessandro
2016-01-01
This book provides an up-to-date description of the methods needed to face the existence of solutions to some nonlinear boundary value problems. All important and interesting aspects of the theory of periodic solutions of ordinary differential equations related to the physical and mathematical question of resonance are treated. The author has chosen as a model example the periodic problem for a second order scalar differential equation. In a paedagogical style the author takes the reader step by step from the basics to the most advanced existence results in the field.
Directory of Open Access Journals (Sweden)
Chuanyi Zhang
2008-06-01
Full Text Available We investigate the existence of almost-periodic weak solutions of second-order neutral delay-differential equations with piecewise constant argument of the form (x(t+x(tÃ¢ÂˆÂ’1Ã¢Â€Â²Ã¢Â€Â²=qx(2[(t+1/2]+f(t, where [Ã¢Â‹Â…] denotes the greatest integer function, q is a real nonzero constant, and f(t is almost periodic.
International Nuclear Information System (INIS)
Ding Xiaohua; Su Huan; Liu Mingzhu
2008-01-01
The paper analyzes a discrete second-order, nonlinear delay differential equation with negative feedback. The characteristic equation of linear stability is solved, as a function of two parameters describing the strength of the feedback and the damping in the autonomous system. The existence of local Hopf bifurcations is investigated, and the direction and stability of periodic solutions bifurcating from the Hopf bifurcation of the discrete model are determined by the Hopf bifurcation theory of discrete system. Finally, some numerical simulations are performed to illustrate the analytical results found
Directory of Open Access Journals (Sweden)
Mervan Pašić
2014-01-01
Full Text Available We study oscillatory behaviour of a large class of second-order functional differential equations with three freedom real nonnegative parameters. According to a new oscillation criterion, we show that if at least one of these three parameters is large enough, then the main equation must be oscillatory. As an application, we study a class of Duffing type quasilinear equations with nonlinear time delayed feedback and their oscillations excited by the control gain parameter or amplitude of forcing term. Finally, some open questions and comments are given for the purpose of further study on this topic.
DEFF Research Database (Denmark)
Ding, Tao; Li, Cheng; Yang, Yongheng
2017-01-01
The detailed topology of renewable resource bases may have the impact on the optimal power flow of the VSC-HVDC transmission network. To address this issue, this paper develops an optimal power flow with the hybrid VSC-HVDC transmission and active distribution networks to optimally schedule...... the generation output and voltage regulation of both networks, which leads to a non-convex programming model. Furthermore, the non-convex power flow equations are based on the Second Order Cone Programming (SOCP) relaxation approach. Thus, the proposed model can be relaxed to a SOCP that can be tractably solved...
Directory of Open Access Journals (Sweden)
Yasushi Narushima
2013-01-01
Full Text Available We deal with complementarity problems over second-order cones. The complementarity problem is an important class of problems in the real world and involves many optimization problems. The complementarity problem can be reformulated as a nonsmooth system of equations. Based on the smoothed Fischer-Burmeister function, we construct a smoothing Newton method for solving such a nonsmooth system. The proposed method controls a smoothing parameter appropriately. We show the global and quadratic convergence of the method. Finally, some numerical results are given.
Kashchenko, Sergey A.
2016-12-01
The dynamics of second-order equations with nonlinear delayed feedback and a large coefficient of a delayed equation is investigated using asymptotic methods. Based on special methods of quasi-normal forms, a new construction is elaborated for obtaining the main terms of asymptotic expansions of asymptotic residual solutions. It is shown that the dynamical properties of the above equations are determined mostly by the behavior of the solutions of some special families of parabolic boundary value problems. A comparative analysis of the dynamics of equations with the delayed feedback of three types is carried out.
International Nuclear Information System (INIS)
Paranin, V D; Karpeev, S V; Khonina, S N; Tukmakov, K N
2016-01-01
Transformation of zero-order Bessel beams into a second-order vortex beam in the process of propagation in a c-cut of lithium niobate LiNbO 3 crystal has been investigated experimentally. The possibility of controlling beam transformation by means of changing the curve radius of the illuminating beam is shown. The possibility of Bessel beam transforming by compact devices on the basis of thin c-cuts of uniaxial crystals with a diffraction mask formed on their surface is proved. (paper)
Directory of Open Access Journals (Sweden)
Vujaković Jelena
2016-01-01
Full Text Available The study of complex differential equations in recent years has opened up some of questions concerning the determination of the frequency of zero solutions, the distribution of zero, oscillation of the solution, asymptotic behavior, rank growth and so on. Besides, this is solved by only some classes of differential equations. In this paper, our aim was to determine the number of zeros and their arrangement in the first quadrant, for the complex canonical differential equation of the second order. The accuracy of our results, we illustrate with two examples.
International Nuclear Information System (INIS)
Karlström, O; Pedersen, J N; Bergenfeldt, C; Samuelsson, P; Wacker, A; Emary, C; Zedler, P; Brandes, T
2013-01-01
We investigate the second-order von Neumann approach from a diagrammatic point of view and demonstrate its equivalence with the resonant tunneling approximation. The investigation of higher order diagrams shows that the method correctly reproduces the equation of motion for the single-particle reduced density matrix of an arbitrary non-interacting many-body system. This explains why the method reproduces the current exactly for such systems. We go on to show, however, that diagrams not included in the method are needed to calculate exactly higher cumulants of the charge transport. This thorough comparison sheds light on the validity of all these self-consistent second-order approaches. We analyze the discrepancy between the noise calculated by our method and the exact Levitov formula for a simple non-interacting quantum dot model. Furthermore, we study the noise of the canyon of current suppression in a two-level dot, a phenomenon that requires the inclusion of electron–electron interaction as well as higher order tunneling processes. (paper)
Evidence for a second-order phase transition around 350 K in Ce3Rh4Sn13
Kuo, C. N.; Chen, W. T.; Tseng, C. W.; Hsu, C. J.; Huang, R. Y.; Chou, F. C.; Kuo, Y. K.; Lue, C. S.
2018-03-01
We report an observation of a phase transition in Ce3Rh4Sn13 with the transition temperature T*≃350 K by means of synchrotron x-ray powder diffraction, specific heat, electrical resistivity, Seebeck coefficient, thermal conductivity, as well as 119Sn nuclear magnetic resonance (NMR) measurements. The phase transition has been characterized by marked features near T* in all measured physical quantities. The lack of thermal hysteresis in the specific heat indicates a second-order phase transition in nature. From the NMR analysis, the change in the transferred hyperfine coupling constant for two tin sites has been resolved. The obtained result has been associated with the reduction in the averaged interatomic distance between Ce and Sn atoms, particularly for the Sn2 atoms. It indicates that the movement of the Sn2 atoms, which deforms the high-temperature structure, shortens the Ce-Sn2 bond length at low temperatures. We therefore provide a concise picture that the observed second-order phase transition at T* of Ce3Rh4Sn13 should be characterized by a structural modulation essentially due to lattice distortions arising from phonon instability.
International Nuclear Information System (INIS)
Keskin, Mustafa; Canko, Osman
2005-01-01
The relaxation behavior of the spin-3/2 Ising model Hamiltonian with bilinear and biquadratic interactions near the second-order phase transition temperature or critical temperature is studied by means of the Onsager's theory of irreversible thermodynamics or the Onsager reciprocity theorem (ORT). First, we give the equilibrium case briefly within the molecular-field approximation in order to study the relaxation behavior by using the ORT. Then, the ORT is applied to the model and the kinetic equations are obtained. By solving these equations, three relaxation times are calculated and examined for temperatures near the second-order phase transition temperature. It is found that one of the relaxation times goes to infinity near the critical temperature on either side, the second relaxation time makes a cusp at the critical temperature and third one behaves very differently in which it terminates at the critical temperature while approaching it, then showing a 'flatness' property and then decreases. We also study the influences of the Onsager rate coefficients on the relaxation times. The behavior of these relaxation times is discussed and compared with the spin-1/2 and spin-1 Ising systems
Mei, Jie; Ren, Wei; Li, Bing; Ma, Guangfu
2015-09-01
In this paper, we consider the distributed containment control problem for multiagent systems with unknown nonlinear dynamics. More specifically, we focus on multiple second-order nonlinear systems and networked Lagrangian systems. We first study the distributed containment control problem for multiple second-order nonlinear systems with multiple dynamic leaders in the presence of unknown nonlinearities and external disturbances under a general directed graph that characterizes the interaction among the leaders and the followers. A distributed adaptive control algorithm with an adaptive gain design based on the approximation capability of neural networks is proposed. We present a necessary and sufficient condition on the directed graph such that the containment error can be reduced as small as desired. As a byproduct, the leaderless consensus problem is solved with asymptotical convergence. Because relative velocity measurements between neighbors are generally more difficult to obtain than relative position measurements, we then propose a distributed containment control algorithm without using neighbors' velocity information. A two-step Lyapunov-based method is used to study the convergence of the closed-loop system. Next, we apply the ideas to deal with the containment control problem for networked unknown Lagrangian systems under a general directed graph. All the proposed algorithms are distributed and can be implemented using only local measurements in the absence of communication. Finally, simulation examples are provided to show the effectiveness of the proposed control algorithms.
P1-17: Pseudo-Haptics Using Motion-in-Depth Stimulus and Second-Order Motion Stimulus
Directory of Open Access Journals (Sweden)
Shuichi Sato
2012-10-01
Full Text Available Modification of motion of the computer cursor during the manipulation by the observer evokes illusory haptic sensation (Lecuyer et al., 2004 ACM SIGCHI '04 239–246. This study investigates the pseudo-haptics using motion-in-depth and second-order motion. A stereoscopic display and a PHANTOM were used in the first experiment. A subject was asked to move a visual target at a constant speed in horizontal, vertical, or front-back direction. During the manipulation, the speed was reduced to 50% for 500 msec. The haptic sensation was measured using the magnitude estimation method. The result indicates that perceived haptic sensation from motion-in-depth was about 30% of that from horizontal or vertical motion. A 2D display and the PHANTOM were used in the second experiment. The motion cue was second order—in each frame, dots in a square patch reverses in contrast (i.e., all black dots become white and all white dots become black. The patch was moved in a horizontal direction. The result indicates that perceived haptic sensation from second-order motion was about 90% of that from first-order motion.