WorldWideScience

Sample records for external periodic force

  1. Stability of GOY Model Under Modulation of Periodic External Force

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ying-Kui; CHEN Shi-Gang; WANG Guang-Rui

    2008-01-01

    There is a phase transition between quasi-periodic state and intermittent chaos in GOY model with a critical value δ0. When we add a modulated periodic external force to the system, the phase transition can also be found with a critical value δe. Due to coupling between the force and the intrinsic fluctuation of the velocity on shells in GOY model, the stability of the system has been changed, which results in the variation of the critical value. For proper intensity and period of the force, δe is unequal to δ0. The critical value is a nonlinear function of amplitude of the force, and the fluctuation of the velocity can resonate with the external force for certain period Te.

  2. External Periodic Force Control of a Single-Degree-of-Freedom Vibroimpact System

    Directory of Open Access Journals (Sweden)

    Jingyue Wang

    2013-01-01

    Full Text Available A single-degree-of-freedom mechanical model of vibro-impact system is established. Bifurcation and chaos in the system are revealed with the time history diagram, phase trajectory map, and Poincaré map. According to the bifurcation and chaos of the actual vibro-impact system, the paper puts forward external periodic force control strategy. The method of controlling chaos by external periodic force feedback controller is developed to guide chaotic motions towards regular motions. The stability of the control system is also analyzed especially by theory. By selecting appropriate feedback coefficients, the unstable periodic orbits of the original chaotic orbit can be stabilized to the stable periodic orbits. The effectiveness of this control method is verified by numerical simulation.

  3. Synchronization of cardiorhythm by weak external forcing

    Directory of Open Access Journals (Sweden)

    V. S. Anishchenko

    2000-01-01

    Full Text Available We study the possibility to synchronize cardiorhythm of a human by periodic and aperiodic sequences of light and sound pulses. Aperiodic forcing is defined by variation of RR intervals of another subject. Phase locking between cardiorhythm and weak external forcing is detected on finite time intervals. We observe the 1:1 synchronization for periodic forcing and n:m synchronization for aperiodic one.

  4. Effect of dust ion collision on dust ion acoustic waves in the framework of damped Zakharov-Kuznetsov equation in presence of external periodic force

    Science.gov (United States)

    Kanti Das, Tushar; Ali, Rustam; Chatterjee, Prasanta

    2017-10-01

    The dynamics of dust ion acoustic waves (DIAWs) is investigated in a magnetized dusty plasma whose constituents are cold ions, superthermal electrons, and dust particles in the framework of a damped Zakharov-Kuznetsov (dZK) equation in the presence of externally applied periodic force. The dZK equation is derived employing the standard reductive perturbation technique. The effect of dust ion collision on the quasiperiodic and chaotic motion of dust ion acoustic waves is discussed. It is observed that the collision frequency νid 0 plays the role of a switching parameter from the quasiperiodic route to chaos for the DIAWs.

  5. STUDY OF STATIC AND DYNAMIC STABILITY OF THIN-WALLED BARS EXCITED BY PERIODICAL AXIAL EXTERNAL FORCES.

    Directory of Open Access Journals (Sweden)

    Minodora Maria PASĂRE

    2010-10-01

    Full Text Available In these paper, starting from the relations for the displacements and spinning the transversal section of a bar with thin walls of sections opened expressed by the corresponding influence functions and introducing the components of the exterior forces distributed and the moments of the exterior forces distributed due to the inertia forces, the exciting axial forces together with the following effect of these and of the reaction forces of the elastic environment for leaning it may reach to the system of the equations of parametric vibrations under the form of three integral equation These equations may serve for the study of vibrations of the bars, to study the static stability and to study the dynamic stability

  6. Equatorial Rossby Solitary Wave Under the External Forcing

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Kuo; LIU Shi-Da

    2005-01-01

    A simple shallow-water model with influence of external forcing on a β-plane is applied to investigate the nonlinear equatorial Rossby waves in a shear flow. By the perturbation method, the extended variable-coefficient KdV equation under an external forcing is derived for large amplitude equatorial Rossby wave in a shear flow. And then various periodic-like structures for these equatorial Rossby waves are obtained with the help of Jacobi elliptic functions.It is shown that the external forcing plays an important role in various periodic-like structures.

  7. Internal and External Forces in Language Change.

    Science.gov (United States)

    Yang, Charles D.

    2000-01-01

    Develops a model of language change characterizing the dynamic interaction between internal universal grammar and external linguistic evidence, as mediated by language acquisition. Borrows insights from the study of biological evolution, where internal and external forces interact in similar fashion. Applies the model to explore the loss of the…

  8. Effect of various periodic forces on Duffing oscillator

    Indian Academy of Sciences (India)

    V Ravichandran; V Chinnathambi; S Rajasekar

    2006-08-01

    Bifurcations and chaos in the ubiquitous Duffing oscillator equation with different external periodic forces are studied numerically. The external periodic forces considered are sine wave, square wave, rectified sine wave, symmetric saw-tooth wave, asymmetric saw-tooth wave, rectangular wave with amplitude-dependent width and modulus of sine wave. Period doubling bifurcations, chaos, intermittency, periodic windows and reverse period doubling bifurcations are found to occur due to the applied forces. A comparative study of the effect of various forces is performed.

  9. Atlantic Meridional Overturning Circulation response to idealized external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Park, W.; Latif, M. [Leibniz-Institut fuer Meereswissenschaften an der Universitaet Kiel, Kiel (Germany)

    2012-10-15

    The response of the Atlantic Meridional Overturning Circulation (AMOC) to idealized external (solar) forcing is studied in terms of the internal (unforced) AMOC modes with the Kiel Climate Model (KCM), a coupled atmosphere-ocean-sea ice general circulation model. The statistical investigation of KCM's internal AMOC variability obtained from a multi-millennial control run yields three distinct modes: a multi-decadal mode with a period of about 60 years, a quasi-centennial mode with a period of about 100 years and a multi-centennial mode with a period of about 300-400 years. Most variance is explained by the multi-centennial mode, and the least by the quasi-centennial mode. The solar constant varies sinusoidally with two different periods (100 and 60 years) in forced runs with KCM. The AMOC response to the external forcing is rather complex and nonlinear. It involves strong changes in the frequency structure of the variability. While the control run depicts multi-timescale behavior, the AMOC variability in the experiment with 100 year forcing period is channeled into a relatively narrow band centered near the forcing period. It is the quasi-centennial AMOC mode with a period of just under 100 years which is excited, although it is heavily damped in the control run. Thus, the quasi-centennial mode retains its period which does not correspond exactly to the forcing period. Surprisingly, the quasi-centennial mode is also most strongly excited when the forcing period is set to 60 years, the period of the multi-decadal mode which is rather prominent in the control run. It is largely the spatial structure of the forcing rather than its period that determines which of the three internal AMOC modes is excited. The results suggest that we need to understand the full modal structure of the internal AMOC variability in order to understand the circulation's response to external forcing. This could be a challenge for climate models: we cannot necessarily expect that the

  10. Ratchet effect on a relativistic particle driven by external forces

    Energy Technology Data Exchange (ETDEWEB)

    Quintero, Niurka R [Departamento de Fisica Aplicada I, Escuela Universitaria Politecnica, Universidad de Sevilla, Calle Virgen de Africa 7, E-41011 Sevilla (Spain); Alvarez-Nodarse, Renato [Departamento de Analisis Matematico, Facultad de Matematicas, Universidad de Sevilla, Apdo 1160, E-41080 Sevilla (Spain); Cuesta, Jose A, E-mail: niurka@us.es, E-mail: ran@us.es, E-mail: cuesta@math.uc3m.es [Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matematicas, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911 Leganes, Madrid (Spain)

    2011-10-21

    We study the ratchet effect of a damped relativistic particle driven by both asymmetric temporal bi-harmonic and time-periodic piecewise constant forces. This system can be formally solved for any external force, providing the ratchet velocity as a nonlinear functional of the driving force. This allows us to explicitly illustrate the functional Taylor expansion formalism recently proposed for this kind of systems. The Taylor expansion reveals particularly useful to obtain the shape of the current when the force is periodic, piecewise constant. We also illustrate the somewhat counterintuitive effect that introducing damping may induce a ratchet effect. When the force is symmetric under time-reversal and the system is undamped, under symmetry principles no ratchet effect is possible. In this situation increasing damping generates a ratchet current which, upon increasing the damping coefficient eventually reaches a maximum and decreases toward zero. We argue that this effect is not specific of this example and should appear in any ratchet system with tunable damping driven by a time-reversible external force. (paper)

  11. Spatiotemporal complexity of a predator-prey system with the effect of noise and external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Rao Feng [Institute of Nonlinear Analysis, College of Mathematics and Information Science, Wenzhou University, Wenzhou 325035 (China); Wang Weiming [Institute of Nonlinear Analysis, College of Mathematics and Information Science, Wenzhou University, Wenzhou 325035 (China)], E-mail: weimingwang2003@163.com; Li Zhenqing [Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093 (China)

    2009-08-30

    In this paper, we present a spatial version of the Ivlev-type predator-prey model which contains some important factors, such as noise on predator, external periodic forcing and diffusion processes on both predator and prey. From the numerical results, we know that noise or external periodic forcing can induce instability and enhance the oscillation of the species density, and the cooperation between noise and external periodic forcing inherent to the deterministic dynamics of periodically driven models gives rise to the appearance of a rich transport phenomenology. Furthermore, we demonstrate that the spatially extended system exhibits a resonant patterns and frequency-locking phenomena. Our results show that noise and external periodic forcing play a prominent role in the predator-prey model.

  12. EXTERNAL BODY FORCE IN FINITE DIFFERENCE LATTICE BOLTZMANN METHOD

    Institute of Scientific and Technical Information of China (English)

    CHEN Sheng; LIU Zhao-hui; SHI Bao-chang; ZHENG Chu-guang

    2005-01-01

    A new finite difference lattice Boltzmann scheme is developed. Because of analyzing the influence of external body force roundly, the correct Navier-Stokes equations with the external body force are recovered, without any additional unphysical terms. And some numerical results are presented. The result which close agreement with analytical data shows the good performance of the model.

  13. Entropic stochastic resonance without external force in oscillatory confined space

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Department of Chemical Physics and Hefei National Laboratory for Physical Sciences at Microscales, iChEM, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-05-21

    We have studied the dynamics of Brownian particles in a confined geometry of dumbbell-shape with periodically oscillating walls. Entropic stochastic resonance (ESR) behavior, characterizing by a maximum value of the coherent factor Q at some optimal level of noise, is observed even without external periodic force in the horizontal direction, which is necessary for conventional ESR where the wall is static and the particle is subjected to the force. Interestingly, the ESR can be remarkably enhanced by the particle gravity G, in contrast to the conventional case. In addition, Q decreases (increases) with G in the small (large) noise limit, respectively, while it non-monotonically changes with G for moderate noise levels. We have applied an effective 1D coarsening description to illustrate such a nontrivial dependence on G, by investigating the property of the 1D effective potential of entropic nature and paying special attention to the excess part resulting from the boundary oscillation. Dependences of the ESR strength with other related parameters are also discussed.

  14. Response of Brownian Fluctuations to External Forces

    Science.gov (United States)

    Laub, Jeffrey William

    Millikan's law of particle fall is an empirical result which shows the dependence of particle fall rate in a gas on particle radius and host gas density. The size of submicron particles in gases has long been determined by Millikan's law. The dominant factor is Stokes' law with a correction added to account for the physics of slip. However, it was recently shown by Kim and Fedele that Brownian fluctuations affect the fall rate while showing no anomalies in the density dependence of the rms displacement. The effect was an enhancement of the fall rate of small particles as the density of the host gas is increased. This enhancement showed a size dependence in the form of a smooth transition from the one of decreasing fall rate with increasing density for large particles (~0.4 μm radius) to another of increasing fall rate with increasing gas density for small particles ( ~0.15mum radius). The magnitude of the anomaly is determined by how the rms Brownian velocity compares with its fall rate. In an effort to understand the effect of Brownian fluctuations coupling with gravity, a new experiment has been carried out where an AC field was applied to force particles to fluctuate more in the vertical direction on one hand and where a constant DC field was applied to change the effective force of gravity on the other. These fields were applied to a charged oil drop in the 0.2 to 0.3 μm radius range falling in a nitrogen environment. Displacements over a 4 second time interval were repeatedly measured in both the vertical and horizontal directions. The original experimental apparatus was used with some modifications. The modifications included computer automation of particle control and data taking to allow for longer use of the same particle, up to 120 hours, and to facilitate application of the additional fields. The objective was to make large particles appear to be smaller via forced oscillations and make them fall faster or slower via the DC bias to effect the change in

  15. EEO External Relevant Labor Force Analysis

    Science.gov (United States)

    1980-09-01

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  16. Decadal period external magnetic field variations determined via eigenanalysis

    DEFF Research Database (Denmark)

    Shore, R. M.; Whaler, K. A.; Macmillan, S.

    2016-01-01

    We perform a reanalysis of hourly mean magnetic data from ground-based observatories spanning 1997-2009 inclusive, in order to isolate (after removal of core and crustal field estimates) the spatiotemporal morphology of the external fields important to mantle induction, on (long) periods of months......-the form of the decomposition is controlled by the data. We apply a spherical harmonic analysis to the EOF outputs in a joint inversion for internal and external coefficients. The results justify our assumption that the EOF procedure responds primarily to the long-period external inducing field...... contributions. Though we cannot determine uniquely the contributory source regions of these inducing fields, we find that they have distinct temporal characteristics which enable some inference of sources. An identified annual-period pattern appears to stem from a north-south seasonal motion of the background...

  17. Impacts of external forcing on the 20th century global warming

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The impacts of external forcing, including natural and anthropogenic, on the 20th century global warming were assessed with the use of the Grid Atmospheric Model of IAP/LASG Version 1.1.0, following the standard coordinated experiment design of the Climate Variability and Predictability (CLIVAR) International Climate of the Twentieth Century Project (C20C), Phase II. The results indicate that external forcing plays an important role in the evolution of the land surface air temperature on interannual, decadal, and interdecadal time scales, and contributes greatly to the global warming in the following two periods: the early twentieth century between the 1910s and the 1940s and the late twentieth century after the 1970s. External forcing also has strong impact on the regional temperature change during the two warming periods except for parts of the Eurasia and the North America continents. In the cooling period, however, the impact of internal variability is dominant.

  18. Periodic Orbit Theory for Rydberg Atoms in External Fields

    Science.gov (United States)

    Dando, P. A.; Monteiro, T. S.; Owen, S. M.

    1998-03-01

    Although hydrogen in external fields is a paradigm for the application of periodic orbits and the Gutzwiller trace formula to a real system, the trace formula has never been applied successfully to other Rydberg atoms. We show that spectral fluctuations of general Rydberg atoms are given with remarkable precision by the addition of diffractive terms. Previously unknown features in atomic spectra are exposed: there are new modulations that are neither periodic orbits nor combinations of periodic orbits; ``core shadowing'' generally decreases primitive periodic orbit amplitudes but can also lead to increases.

  19. Periodic Orbit Theory for Rydberg Atoms in External Fields

    CERN Document Server

    Dando, P A; Owen, S M

    1998-01-01

    Although hydrogen in external fields is a paradigm for the application of periodic orbits and the Gutzwiller trace formula to a real system, the trace formula has never been applied successfully to other Rydberg atoms. We show that spectral fluctuations of general Rydberg atoms are given with remarkable precision by the addition of diffractive terms. Previously unknown features in atomic spectra are exposed: there are new modulations that are neither periodic orbits nor combinations of periodic orbits; `core-shadowing' generally decreases primitive periodic orbit amplitudes but can also lead to increases.

  20. Periodicity in bimodal atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Chia-Yun; Santos, Sergio, E-mail: santos-en@yahoo.com; Chiesa, Matteo [Laboratory for Energy and NanoScience (LENS), Institute Center for Future Energy (iFES), Masdar Institute of Science and Technology, Abu Dhabi (United Arab Emirates); Barcons, Victor [Departament de Disseny i Programació de Sistemes Electrònics, UPC - Universitat Politècnica de Catalunya, Av. Bases, 61, 08242 Manresa (Barcelona) (Spain)

    2015-07-28

    Periodicity is fundamental for quantification and the application of conservation principles of many important systems. Here, we discuss periodicity in the context of bimodal atomic force microscopy (AFM). The relationship between the excited frequencies is shown to affect and control both experimental observables and the main expressions quantified via these observables, i.e., virial and energy transfer expressions, which form the basis of the bimodal AFM theory. The presence of a fundamental frequency further simplifies the theory and leads to close form solutions. Predictions are verified via numerical integration of the equation of motion and experimentally on a mica surface.

  1. Manipulating single enzymes by an external harmonic force

    DEFF Research Database (Denmark)

    Lomholt, Michael A; Urbakh, Michael; Metzler, Ralf

    2007-01-01

    We study a Michaelis-Menten reaction for a single two-state enzyme molecule, whose transition rates between the two conformations are modulated by an harmonically oscillating external force. In particular, we obtain a range of optimal driving frequencies for changing the conformation of the enzyme...

  2. External Force Estimation for Teleoperation Based on Proprioceptive Sensors

    Directory of Open Access Journals (Sweden)

    Enrique del Sol

    2014-03-01

    Full Text Available This paper establishes an approach to external force estimation for telerobotic control in radioactive environments by the use of an identified manipulator model and pressure sensors, without employing a force/torque sensor. The advantages of - and need for - force feedback have been well-established in the field of telerobotics, where electrical and back-drivable manipulators have traditionally been used. This research proposes a methodology employing hydraulic robots for telerobotics tasks based on a model identification scheme. Comparative results of a force sensor and the proposed approach using a hydraulic telemanipulator are presented under different conditions. This approach not only presents a cost effective solution but also a methodology for force estimation in radioactive environments, where the dose rates limit the use of electronic devices such as sensing equipment.

  3. Power, muscular work, and external forces in cycling.

    Science.gov (United States)

    de Groot, G; Welbergen, E; Clijsen, L; Clarijs, J; Cabri, J; Antonis, J

    1994-01-01

    Cycling performance is affected by the interaction of a number of variables, including environment, mechanical, and human factors. Engineers have focused on the development of more efficient bicycles. Kinesiologists have examined cycling performance from a human perspective. This paper summarizes only certain aspects of human ergonomics of cycling, especially those which are important for the recent current research in our departments. Power is a key to performance of physical work. During locomotion an imaginary flow of energy takes place from the metabolism to the environment, with some efficiency. The 'useful' mechanical muscle power output might be used to perform movements and to do work against the environment. The external power is defined as the sum of joint powers, each calculated as the product of the joint (net) moment and angular velocity. This definition of external power is closely related to the mean external power as applied to exercise physiology: the sum of joint powers reflects all mechanical power which in principle can be used to fulfil a certain task. In this paper, the flow of energy for cycling is traced quantitatively as far as possible. Studies on the total lower limb can give insight into the contribution of individual muscles to external power. The muscle velocity (positive or negative) is obtained from the positions and orientations of body segments and a bar linkage model of the lower limb. The muscle activity can be measured by electromyography. In this way, positive and negative work regions in individual muscles are identified. Synergy between active agonistic/antagonistic muscle groups occurs in order to deliver external power. Maximum power is influenced by body position, geometry of the bicycle and pedalling rate. This has to be interpreted in terms of the length-tension and force-velocity-power relationships of the involved muscles. Flat road and uphill cycling at different saddle-tube angles is simulated on an ergometer. The

  4. Manipulating single enzymes by an external harmonic force

    DEFF Research Database (Denmark)

    Lomholt, Michael A; Urbakh, Michael; Metzler, Ralf

    2007-01-01

    We study a Michaelis-Menten reaction for a single two-state enzyme molecule, whose transition rates between the two conformations are modulated by an harmonically oscillating external force. In particular, we obtain a range of optimal driving frequencies for changing the conformation of the enzyme......, thereby controlling the enzymatic activity (i.e., product formation). This analysis demonstrates that it is, in principle, possible to obtain information about particular rates within the kinetic scheme....

  5. Responses of a Noisy Excitable System to External Signals with Different Periods

    Institute of Scientific and Technical Information of China (English)

    JIA Xun; ZHOU Lu-Qun; OUYANG Qi

    2004-01-01

    @@ The behaviour of an excitable system under Gaussian white noise and external periodic forcing is systematically studied. In a large range of noise intensity, the n:1 phase locking patterns are obtained for certain ranges of the input periods, where n input periods give one spike. In the phase locking regimes, the system presents low noise-to-signal ratios and shows better regularities. Out of the regimes the system behavesless regularly and the relations between the noise-to-signal ratio and the noise intensity exhibit typical stochastic resonance phenomena.At a higher noise level, the system shows the characteristic behaviour of the noise.

  6. Pattern transformations in periodic cellular solids under external stimuli

    Science.gov (United States)

    Zhang, K.; Zhao, X. W.; Duan, H. L.; Karihaloo, B. L.; Wang, J.

    2011-04-01

    The structural patterns of periodic cellular materials play an important role in their properties. Here, we investigate how these patterns transform dramatically under external stimuli in simple periodic cellular structures that include a nanotube bundle and a millimeter-size plastic straw bundle. Under gradual hydrostatic straining up to 20%, the cross-section of the single walled carbon nanotube bundle undergoes several pattern transformations, while an amazing new hexagram pattern is triggered from the circular shape when the strain of 20% is applied suddenly in one step. Similar to the nanotube bundle, the circular plastic straw bundle is transformed into a hexagonal pattern on heating by conduction through a baseplate but into a hexagram pattern when heated by convection. Besides the well-known elastic buckling, we find other mechanisms of pattern transformation at different scales; these include the minimization of the surface energy at the macroscale or of the van der Waals energy at the nanoscale and the competition between the elastic energy of deformation and either the surface energy at the macroscale or the van der Waals energy at the nanoscale. The studies of the pattern transformations of periodic porous materials offer new insights into the fabrication of novel materials and devices with tailored properties.

  7. Numerical studies of a plasma diode with external forcing

    Science.gov (United States)

    Rekaa, V. L.; Pécseli, H. L.; Trulsen, J. K.

    2012-08-01

    With reference to laboratory Q-machine studies we analyze the dynamics of a plasma diode under external forcing. Assuming a strong axial magnetic field, the problem is analyzed in one spatial dimension by a particle-in-cell code. The cathode is assumed to be operated in electron rich conditions, supplying an abundance of electrons. We compare different forcing schemes with the results obtained by solving the van der Pol equation. In one method of forcing we apply an oscillation in addition to the DC end plate bias and consider both amplitude and frequency variations. An alternative method of perturbation consists of modelling an absorbing grid at some internal position. Also in this case we can have a constant frequency with varying amplitude or alternatively an oscillation with chirped frequency but constant amplitude. We find that the overall features of the forced van der Pol equation are recovered, but the details in the plasma response need more attention to the harmonic responses, requiring extensions of the model equation. The analysis is extended by introducing collisional effects, where we emphasize charge exchange collisions of ions, since these processes usually have the largest cross sections and give significant modifications of the diode performance. In particular we find a reduction in oscillator frequency, although a linear scaling of the oscillation time with the system length remains also in this case.

  8. Phase separation in fluids exposed to spatially periodic external fields.

    Science.gov (United States)

    Vink, R L C; Archer, A J

    2012-03-01

    When a fluid is confined within a spatially periodic external field, the liquid-vapor transition is replaced by a different transition called laser-induced condensation (LIC) [Götze et al., Mol. Phys. 101, 1651 (2003)]. In d=3 dimensions, the periodic field induces an additional phase, characterized by large density modulations along the field direction. At the triple point, all three phases (modulated, vapor, and liquid) coexist. At temperatures slightly above the triple point and for low (high) values of the chemical potential, two-phase coexistence between the modulated phase and the vapor (liquid) is observed; by increasing the temperature further, both coexistence regions terminate in critical points. In this paper, we reconsider LIC using the Ising model to resolve a number of open issues. To be specific, we (1) determine the universality class of the LIC critical points and elucidate the nature of the correlations along the field direction, (2) present a mean-field analysis to show how the LIC phase diagram changes as a function of the field wavelength and amplitude, (3) develop a simulation method by which the extremely low tension of the interface between modulated and vapor or liquid phase can be measured, (4) present a finite-size scaling analysis to accurately extract the LIC triple point from finite-size simulation data, and (5) consider the fate of LIC in d=2 dimensions.

  9. Enhanced Diffusion of Molecular Motors in the Presence of Adenosine Triphosphate and External Force

    Science.gov (United States)

    Shinagawa, Ryota; Sasaki, Kazuo

    2016-06-01

    The diffusion of a molecular motor in the presence of a constant external force is considered on the basis of a simple theoretical model. The motor is represented by a Brownian particle moving in a series of parabolic potentials placed periodically on a line, and the potential is switched stochastically from one parabola to another by a chemical reaction, which corresponds to the hydrolysis or synthesis of adenosine triphosphate (ATP) in motor proteins. It is found that the diffusion coefficient as a function of the force exhibits peaks. The mechanism of this diffusion enhancement and the possibility of observing it in F1-ATPase, a biological rotary motor, are discussed.

  10. Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models

    Science.gov (United States)

    Alvarez-Nodarse, R.; Quintero, N. R.; Mertens, F. G.

    2014-10-01

    A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.

  11. Kink topology control by high-frequency external forces in nonlinear Klein-Gordon models.

    Science.gov (United States)

    Alvarez-Nodarse, R; Quintero, N R; Mertens, F G

    2014-10-01

    A method of averaging is applied to study the dynamics of a kink in the damped double sine-Gordon equation driven by both external (nonparametric) and parametric periodic forces at high frequencies. This theoretical approach leads to the study of a double sine-Gordon equation with an effective potential and an effective additive force. Direct numerical simulations show how the appearance of two connected π kinks and of an individual π kink can be controlled via the frequency. An anomalous negative mobility phenomenon is also predicted by theory and confirmed by simulations of the original equation.

  12. Macroscopic entrainment of periodically forced oscillatory ensembles.

    Science.gov (United States)

    Popovych, Oleksandr V; Tass, Peter A

    2011-03-01

    Large-amplitude oscillations of macroscopic neuronal signals, such as local field potentials and electroencephalography or magnetoencephalography signals, are commonly considered as being generated by a population of mutually synchronized neurons. In a computational study in generic networks of phase oscillators and bursting neurons, however, we show that this common belief may be wrong if the neuronal population receives an external rhythmic input. The latter may stem from another neuronal population or an external, e.g., sensory or electrical, source. In that case the population field potential may be entrained by the rhythmic input, whereas the individual neurons are phase desynchronized both mutually and with their field potential. Intriguingly, the corresponding large-amplitude oscillations of the population mean field are generated by pairwise desynchronized neurons oscillating at frequencies shifted far away from the frequency of the macroscopic field potential.

  13. H Infinity Control of Magnetic Bearings to Ensure Both System and External Periodic Disturbance Robustness

    Science.gov (United States)

    Jiang, Yuhong; Zmood, R. B.

    1996-01-01

    Both self-excited and forced disturbances often lead to severe rotor vibrations in a magnetic bearing systems with long slender shafts. This problem has been studied using the H-infinity method, and stability with good robustness can be achieved for the linearized model of a magnetic bearing when small transient disturbances are applied. In this paper, the H-infinity control method for self-excited and forced disturbances is first reviewed. It is then applied to the control of a magnetic bearing rotor system. In modelling the system, the shaft is first discretized into 18 finite elements and then three levels of condensation are applied. This leads to a system with three masses and three compliant elements which can be described by six state variable coordinates. Simulation of the resultant system design has been performed at speeds up to 10,000 rpm. Disturbances in terms of different initial displacements, initial impulses, and external periodic inputs have been imposed. The simulation results show that good stability can be achieved under these different transient disturbances using the proposed controller while at the same time reducing the sensitivity to external periodic disturbances.

  14. Effects of Periodic Forcing Amplitude on the Spiral Wave Resonance Drift

    Institute of Scientific and Technical Information of China (English)

    WU Ning-Jie; LI Bing-Wei; YING He-Ping

    2006-01-01

    @@ We study dynamics of spiral waves under a uniform periodic temporal forcing in an excitable medium. With a specific combination of frequency and amplitude of the external periodic forcing, a resonance drift of a spiral wave occurs along a straight line, and it is accompanied by a complicated ‘flower-like’ motion on each side of this bifurcate boundary line. It is confirmed that the straight-line drift frequency of spiral waves is not locked to the nature rotation frequency as the forcing amplitude expends the range of the spiral wave frequency. These results are further verified numerically for a simplified kinematical model.

  15. Dissipative Quasigeostrophic Motion under Temporally Almost Periodic Forcing

    CERN Document Server

    Duan, J; Duan, Jinqiao; Kloeden, Peter E.

    1999-01-01

    The full nonlinear dissipative quasigeostrophic model is shown to have a unique temporally almost periodic solution when the wind forcing is temporally almost periodic under suitable constraints on the spatial square-integral of the wind forcing and the $\\beta$ parameter, Ekman number, viscosity and the domain size. The proof involves the pullback attractor for the associated nonautonomous dynamical system.

  16. Quantifying internally generated and externally forced climate signals at regional scales in CMIP5 models

    Science.gov (United States)

    Lyu, Kewei; Zhang, Xuebin; Church, John A.; Hu, Jianyu

    2015-11-01

    The Earth's climate evolves because of both internal variability and external forcings. Using Coupled Model Intercomparison Project Phase 5 (CMIP5) models, here we quantify the ratio of externally forced variance to total variance on interannual and longer time scales for regional surface air temperature (SAT) and sea level, which depends on the relative strength of externally forced signal compared to internal variability. The highest ratios are found in tropical areas for SAT but at high latitudes for sea level over the historical period when ocean dynamics and global mean thermosteric contributions are considered. Averaged globally, the ratios over a fixed time interval (e.g., 30 years) are projected to increase during the 21st century under the business-as-usual scenario (RCP8.5). In contrast, under two mitigation scenarios (RCP2.6 and RCP4.5), the ratio declines sharply by the end of the 21st century for SAT, but only declines slightly or stabilizes for sea level, indicating a slower response of sea level to climate mitigation.

  17. Rich dynamics in a predator–prey model with both noise and periodic force

    NARCIS (Netherlands)

    Sun, G.Q.; Jin, Z.; Liu, Q.X.; Li, B.L.

    2010-01-01

    A spatial version of the predator–prey model with Holling III functional response, which includes some important factors such as external periodic forces, noise, and diffusion processes is investigated. For the model only with diffusion, it exhibits spiral waves in the two-dimensional space. However

  18. Monsoonal Responses to External Forcings over the Past Millennium: A Model Study (Invited)

    Science.gov (United States)

    Liu, J.; Wang, B.

    2009-12-01

    The climate variations related to Global Monsoon (GM) and East Asian summer monsoon (EASM) rainfall over the past 1000 years were investigated by analysis of a pair of millennium simulations with the coupled climate model named ECHO-G. The free run was generated using fixed external (annual cycle) forcing, while the forced run was obtained using time-varying solar irradiance variability, greenhouse gases (CO2 and CH4) concentration and estimated radiative effect of volcanic aerosols. The model results indicate that the centennial-millennial variation of the GM and EASM is essentially a forced response to the external radiative forcings (insolation, volcanic aerosols, and greenhouse gases). The GM strength responds more directly to the effective solar forcing (insolation plus radiative effect of the volcanoes) when compared to responses of the global mean surface temperature on centennial timescale. The simulated GM precipitation in the forced run exhibits a significant quasi-bi-centennial oscillation. Weak GM precipitation was simulated during the Little Ice Age (1450-1850) with three weakest periods concurring with the Spörer, Maunder, and Dalton Minimum of solar activity. Conversely, strong GM was simulated during the model Medieval Warm Period (ca. 1030-1240). Before the industrial period, the natural variation in effective solar forcing reinforces the thermal contrasts both between the ocean and continent and between the northern and southern hemispheres, resulting in millennium-scale variation and the quasi-bi-centennial oscillation of the GM. The prominent upward trend in the GM precipitation occurring in the last century and the remarkably strengthening of the global monsoon in the period of 1961-1990 appear unprecedented and owed possibly in part to the increase of atmospheric carbon dioxide concentration. The EASM has the largest meridional extent (5oN-55oN) among all the regional monsoons on globe. Thus, the EASM provides an unique opportunity for

  19. Novel bursting patterns in a Van der pol-Duffing oscillator with slow varying external force

    Science.gov (United States)

    Yu, Yue; Zhao, Min; Zhang, Zhengdi

    2017-09-01

    In this paper, we investigate the emergence of bursting dynamics with complex waveforms and their relation to periodic behavior in typical Van der pol-Duffing equation with fifth order polynomial stiffness nonlinearity, when the external force changes slowly with the variation of time. We exploit bifurcation characteristics of the fast subsystem using the slowly changing periodic excitation as a bifurcation parameter to show how the bursting oscillations are created in this model. We also identify that some regimes of bursting patterns are related to codimension two bifurcation type over a wide range of parameters. A subsequent two-parameter continuation reveals a transition in the bursting behavior from fold/fold hysteresis cycle to sup-Hopf/sup-Hopf or limit point cycle/sub-Hopf bursting type. Furthermore, the effects of external forcing item on bursting oscillations are investigated. For instance, the time interval between two adjacent spikes of bursting oscillations is dependent on the forcing frequency. Some numerical simulations are included to illustrate the validity of our study.

  20. Influence of external forcings on abrupt millennial-scale climate changes: a statistical modelling study

    Science.gov (United States)

    Mitsui, Takahito; Crucifix, Michel

    2016-07-01

    The last glacial period was punctuated by a series of abrupt climate shifts, the so-called Dansgaard-Oeschger (DO) events. The frequency of DO events varied in time, supposedly because of changes in background climate conditions. Here, the influence of external forcings on DO events is investigated with statistical modelling. We assume two types of simple stochastic dynamical systems models (double-well potential-type and oscillator-type), forced by the northern hemisphere summer insolation change and/or the global ice volume change. The model parameters are estimated by using the maximum likelihood method with the NGRIP Ca^{2+} record. The stochastic oscillator model with at least the ice volume forcing reproduces well the sample autocorrelation function of the record and the frequency changes of warming transitions in the last glacial period across MISs 2, 3, and 4. The model performance is improved with the additional insolation forcing. The BIC scores also suggest that the ice volume forcing is relatively more important than the insolation forcing, though the strength of evidence depends on the model assumption. Finally, we simulate the average number of warming transitions in the past four glacial periods, assuming the model can be extended beyond the last glacial, and compare the result with an Iberian margin sea-surface temperature (SST) record (Martrat et al. in Science 317(5837): 502-507, 2007). The simulation result supports the previous observation that abrupt millennial-scale climate changes in the penultimate glacial (MIS 6) are less frequent than in the last glacial (MISs 2-4). On the other hand, it suggests that the number of abrupt millennial-scale climate changes in older glacial periods (MISs 6, 8, and 10) might be larger than inferred from the SST record.

  1. Imprint of external climate forcing on coastal upwelling in past and future climate

    Directory of Open Access Journals (Sweden)

    N. Tim

    2015-11-01

    Full Text Available The Eastern Boundary Upwelling Systems are the major coastal upwelling regions. The trade winds are driving these upwelling regimes located in the subtropics at the eastern boundary of the Atlantic and Pacific Ocean. Here we analyse the impact of the external climate forcing, e.g. the greenhouse gas concentration, solar activity and volcano eruptions, on these upwelling systems in simulations of ensembles of two Earth System Models. The ensembles contain three simulations for each time period which cover the past millennium (900–1850, the 20th century (1850–2005 and the near future (2006–2100. Using a set of simulations, differing only in their initial conditions, enables us to detect whether the variability is driven internally or externally. Our analysis shows that the variability of the simulated upwelling is to the most driven internally and that there are no significant trends except for the scenario with the most dramatic increase of greenhouse gas concentrations.

  2. External force estimation and implementation in robotically assisted minimally invasive surgery.

    Science.gov (United States)

    Sang, Hongqiang; Yun, Jintian; Monfaredi, Reza; Wilson, Emmanuel; Fooladi, Hadi; Cleary, Kevin

    2017-06-01

    Robotically assisted minimally invasive surgery can offer many benefits over open surgery and laparoscopic minimally invasive surgery. However, currently, there is no force sensing and force feedback. This research was implemented using the da Vinci research kit. An external force estimation and implementation method was proposed based on dynamics and motor currents. The dynamics of the Patient Side Manipulator was modeled. The dynamic model was linearly parameterized. The estimation principle of external force was derived. The dynamic parameters were experimentally identified using a least squares method. Several experiments including dynamic parameter identification, joint torque estimation, and external force estimation were performed. The results showed that the proposed method could implement force estimation without using a force sensor. The force estimation method was proposed and implemented and experimental results showed the method worked and was feasible. This method could be used for force sensing in minimally invasive surgical robotics in the future. Copyright © 2017 John Wiley & Sons, Ltd.

  3. Experiments on bifurcation of periodic states into tori for a periodically forced chemical oscillator

    Science.gov (United States)

    Vance, William; Ross, John

    1988-05-01

    We study experimentally continuous transitions from quasiperiodic to periodic states for a time-periodically forced chemical oscillator. The chemical reaction is the hydration of 2,3-epoxy-1-propanol, and is carried out in a continuous stirred tank reactor (CSTR). Periodic oscillatory states are observed to arise in the autonomous system through supercritical Hopf bifurcations as either the total flow rate or the cooling coil temperature is changed. Under conditions of oscillation for the autonomous system, small-amplitude periodic variation of the total flow rate generates an attracting two-torus from the stable limit cycle. From the experiments we determine the structure of the toroidal flow, stroboscopic phase portraits, and circle maps as a function of the forcing amplitude and period. A continuous transition from the quasiperiodic to a periodic state, in which the two-torus contracts to a closed curve (Neimark-Sacker torus bifurcation), is observed as the forcing amplitude is increased at a constant forcing period, or as the forcing period is changed at a constant moderate forcing amplitude. Qualitative theoretical predictions compare well with the experimental observations. This paper presents the first experimental observation of a Neimark-Sacker torus bifurcation in a forced chemical oscillator system, and relates the bifurcation diagram of the unforced system to that of the forced system.

  4. Investigation of Multiscale Non-equilibrium Flow Dynamics Under External Force Field

    CERN Document Server

    Xiao, Tianbai

    2016-01-01

    The multiple scale non-equilibrium gaseous flow behavior under external force field is investigated. Both theoretical analysis based on the kinetic model equation and numerical study are presented to demonstrate the dynamic effect of external force on the flow evolution, especially on the non-equilibrium heat flux. The current numerical experiment is based on the well-balanced unified gas-kinetic scheme (UGKS), which presents accurate solutions in the whole flow regime from the continuum Navier-Stokes solution to the transition and free molecular ones. The heat conduction in the non-equilibrium regime due to the external forcing term is quantitatively investigated. In the lid-driven cavity flow study, due to the external force field the density distribution inside cavity gets stratified and a multiscale non-equilibrium flow transport appears in a single gas dynamic system. With the increment of external forcing term, the flow topological structure changes dramatically, and the temperature gradient, shearing s...

  5. External forcing as a source for the observed multi-decadal relation between AMV and the Indian summer monsoon

    Science.gov (United States)

    Svendsen, Lea; Luo, Feifei; Sankar, Syam; Gao, Yongqi; Keenlyside, Noel; Vareed Joseph, Porathur; Johannessen, Ola

    2016-04-01

    The instrumental records show a significant positive correlation between the Atlantic multi-decadal variability (AMV) and the Indian summer monsoon (ISM) rainfall, where a positive (negative) AMV is associated with more (less) ISM rainfall. We have used both proxy reconstruction and twelve models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to investigate if the observed AMV-ISM relation is a persistent internal climate signal or externally forced. A comparison of several annual resolution proxy records both from the Atlantic and for the ISM show that the multi-decadal variability in both indices is persistent, but the link between them is not. The correlation between the two regions is weak, and even negative in some periods, before the instrumental time period. The analysis of CMIP5 simualtions is consistent with these results. While none of the CMIP5 models investigated simulate the significant AMV-ISM connection in the pre-industrial control simulations with fixed external forcing, three of the models reproduce the relation in the 20th century historical simulations with transient forcing. In these models external forcing is linked to the mid-to-upper tropospheric temperature pattern with a strengthened land-ocean contrast over South Asia, consistent with an enhanced ISM, as well as the evolution of AMV. We conclude that the significant AMV-ISM relation found in the observations after the industrial revolution may be associated with external forcing, rather than being internal climate variability.

  6. Vortical flows in strongly coupled Yukawa liquids under external forcing - A molecular dynamics approach

    Science.gov (United States)

    Ganesh, Rajaraman; Charan, Harish

    2016-07-01

    Understanding vortical flows under external forcing in two dimensional (2D) fluids is a fundamental paradigm for structure formation in driven, dissipative systems. Considering Yukawa liquid as a prototype for strongly correlated or strongly coupled plasmas characterized by coupling strength (Γ, the ratio of average potential to kinetic energy per particle) and screening parameter (κ, ratio of mean inter-particle distance to shielding length), we address two important problems: 1. Onset of Rayleigh Benard convection cell (RBCC) in 2D Yukawa liquids subject to gravity and external temperature gradient 2. Onset of von Karman vortices in 2D Yukawa liquid under external pressure head, using large scale, first principles molecular dynamics simulations. For typical values of (Γ,κ), existence of a critical external temperature difference is demonstrated, beyond which RBCC are seen to set in. Beyond this critical external temperature difference, the strength of the maximum convective flow velocity is shown to exhibit a new, hitherto unsuspected linear relationship with external temperature difference and with a slope independent of (Γ,κ). The time taken for the transients to settle down to a steady state RBCC τ_s, is found to be maximum close to the above said critical external temperature difference and is seen to reduce with increasing external temperature difference. For the range of values of (Γ, κ) considered here, τ_s ≃ 10 000-20 000;ω^{-1}_{pd}, where ω_{pd} is dust plasma frequency. As Γ is increased to very high values, due to strong coupling effects, RBC cells are seen to be in a transient state without attaining a steady state for as long as 100 000;ω^{-1}_{pd}, even for a very high external temperature difference. In the second part, we address the existence of universal relation between Strouhal (St) and Rayleigh (Ry) numbers for Yukawa liquid using first principles based classical molecular dynamics. The flow past an obstacle is seen to indeed

  7. Evidence for external forcing temporal clustering of great earthquakes

    Science.gov (United States)

    Khachikyan, Galina; Zhumabayev, Beibit; Toyshiev, Nursultan; Kairatkyzy, Dina; Kaldybayev, Azamat; Nurakynov, Serik

    2016-04-01

    It is shown by Bufe and Perkins [2005, BSSA, doi:10.1785/0120040110] and Shearera and Stark [2012, PNAS, doi: 10.1073/pnas.1118525109] that clustering of great earthquakes in 1950-1965 and 2004-2011 years is highly significant, with a 0.5% probability of random occurrence. Lutikov and Rogozhin [2014, Physics of the Solid Earth] reported on a similar clustering in the end of 19th - beginning of 20ty centuries as well, when strongest earthquakes occurred in Tien Shan (1889, M=8.3; and 1911, M=8.2); Alaska (1899, M=8.0); Kashgaria (1902, M=8.2); Mongolia (1905, M=8.2); San Francisco (1906, M=8.3), China(1906, M=8.3); Columbia (1906, M=8.6). Shearera and Stark [2012] have found that clustering of great earthquakes is analogous to seismic swarms that occur for a limited time. Simultaneously, they mentioned that at present no physical mechanism has been proposed to explain possible global seismicity swarms. Our results suggest that a mechanism responsible for temporal clustering of great earthquakes could be an external one related to the processes in the whole solar system including the Sun. We pay attention that the three marked periods of great earthquake clustering are related closely to the extreme phases of the recent Solar Centennial Gleissberg Cycle, which minimums occurred around of 1913 and 2008 years, and maximum - around of 1960 year. In particular, the great earthquake clustering in 1950-1965 coincides closely with the extremely high 19th eleven year solar cycle lasting from February 1954 to October 1964, while a great earthquake clustering after 2004 year coincides closely with the recent prolonged solar minimum developing after 2000 year. Also, we demonstrate that depending on the structure and composition of the lithosphere, strongest earthquakes may prefer to occur either in high or low solar activity. In particular, data analysis for 32 strongest (M=>7.0) earthquakes occurred in 1973-2014 years in the orogeny region of Eurasia, restricted by coordinates

  8. Experiments of periodic forcing of Saffman-Taylor fingers

    Science.gov (United States)

    Torralba, M.; Ortín, J.; Hernández-Machado, A.; Poiré, E. Corvera

    2008-03-01

    We report on an experimental study of long normal Saffman-Taylor fingers subject to periodic forcing. The sides of the finger develop a low amplitude, long wavelength instability. We discuss the finger response in stationary and nonstationary situations, as well as the dynamics towards the stationary states. The response frequency of the instability increases with forcing frequency at low forcing frequencies, while, remarkably, it becomes independent of forcing frequency at large forcing frequencies. This implies a process of wavelength selection. These observations are in good agreement with previous numerical results reported in [Ledesma-Aguilar , Phys. Rev. E 71, 016312 (2005)]. We also study the average value of the finger width, and its fluctuations, as a function of forcing frequency. The average finger width is always smaller than the width of the steady-state finger. Fluctuations have a nonmonotonic behavior with a maximum at a particular frequency.

  9. Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

    Directory of Open Access Journals (Sweden)

    Luning Shi

    2014-01-01

    Full Text Available A prestress force identification method for externally prestressed concrete uniform beam based on the frequency equation and the measured frequencies is developed. For the purpose of the prestress force identification accuracy, we first look for the appropriate method to solve the free vibration equation of externally prestressed concrete beam and then combine the measured frequencies with frequency equation to identify the prestress force. To obtain the exact solution of the free vibration equation of multispan externally prestressed concrete beam, an analytical model of externally prestressed concrete beam is set up based on the Bernoulli-Euler beam theory and the function relation between prestress variation and vibration displacement is built. The multispan externally prestressed concrete beam is taken as the multiple single-span beams which must meet the bending moment and rotation angle boundary conditions, the free vibration equation is solved using sublevel simultaneous method and the semi-analytical solution of the free vibration equation which considered the influence of prestress on section rigidity and beam length is obtained. Taking simply supported concrete beam and two-span concrete beam with external tendons as examples, frequency function curves are obtained with the measured frequencies into it and the prestress force can be identified using the abscissa of the crosspoint of frequency functions. Identification value of the prestress force is in good agreement with the test results. The method can accurately identify prestress force of externally prestressed concrete beam and trace the trend of effective prestress force.

  10. Musculoskeletal modelling of muscle activation and applied external forces for the correction of scoliosis.

    Science.gov (United States)

    Curtin, Maurice; Lowery, Madeleine M

    2014-04-07

    This study uses biomechanical modelling and computational optimization to investigate muscle activation in combination with applied external forces as a treatment for scoliosis. Bracing, which incorporates applied external forces, is the most popular non surgical treatment for scoliosis. Non surgical treatments which make use of muscle activation include electrical stimulation, postural control, and therapeutic exercises. Electrical stimulation has been largely dismissed as a viable treatment for scoliosis, although previous studies have suggested that it can potentially deliver similarly effective corrective forces to the spine as bracing. The potential of muscle activation for scoliosis correction was investigated over different curvatures both with and without the addition of externally applied forces. The five King's classifications of scoliosis were investigated over a range of Cobb angles. A biomechanical model of the spine was used to represent various scoliotic curvatures. Optimization was applied to the model to reduce the curves using combinations of both deep and superficial muscle activation and applied external forces. Simulating applied external forces in combination with muscle activation at low Cobb angles (forces were applied in combination, lower levels of muscle activation or less external force was required to reduce the curvature of the spine, when compared with either muscle activation or external force applied in isolation. The results of this study suggest that activation of superficial and deep muscles may be effective in reducing spinal curvature at low Cobb angles when muscle groups are selected for activation based on the curve type. The findings further suggest the potential for a hybrid treatment involving combined muscle activation and applied external forces at larger Cobb angles.

  11. Chaos suppression and desynchronization phenomena in periodically coupled pendula subjected to localized heterogeneous forces

    Energy Technology Data Exchange (ETDEWEB)

    Chacon, R. [Departamento de Fisica Aplicada, Escuela de Ingenierias Industriales, Universidad de Extremadura, Apartado Postal 382, E-06071 Badajoz (Spain)], E-mail: rchacon@unex.es; Martinez, P.J. [Departamento de Fisica Aplicada, E.U.I.T.I., Universidad de Zaragoza, Spain and Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Martinez, J.A. [Departamento de Ingenieria Electrica, Electronica y Automatica, E.P.S., Universidad de Castilla-La Mancha, E-02071 Albacete (Spain); Lenci, S. [Dipartimento di Architettura, Costruzioni e Strutture, Universita Politecnica delle Marche, via Brecce Bianche, 60131 Ancona (Italy)

    2009-11-30

    The suppressory effects of localized heterogeneous periodic pulses on the chaotic behaviour of sinusoidally coupled nonlinear pendula are studied. We assume that when the pendula are driven synchronously, i.e., all driving pulses have the same waveform, the chains display chaotic dynamics. It is shown that decreasing the impulse transmitted by the pulses of a minimal number of pendula results in regularization with the whole array exhibiting frequency synchronization over a wide range of coupling periods. These findings demonstrate that decreasing the impulse transmitted by localized external forces can tame chaos and lead to frequency-locked states in networks of periodically coupled dissipative systems.

  12. [Development of external medicine and dermatology of TCM in the Republican period].

    Science.gov (United States)

    He, Zhongjun; Wang, Li

    2015-05-01

    The inheritance of the theory in external medicine in the Republican period was mainly derived from Wai ke zheng zong (Orthodox Manual of External Medicine) and Yi zong jin jian (Golden Mirror of Medicine) and the sorting out of medical plasters, pills, and powders from Wai ke shi san fang (Thirteen Recipes of External Medicine). Zhang Shanlei's Yang ke gang yao (Guidelines for Ulcerations), based on the five-year experience of Zhu's family, offers new experience and ideas for syndrome differentiation; Ding Ganren's diagnosis for external medicine is exquisite with many well known formulae prescribed by himself; Monographs on leprosy and syphilis were published by famous physicians. Departments of external medicine and anal diseases, and classes on external medicine and dermatology and venereal diseases were set up in TCM schools in Guangdong and Zhejiang provinces with teaching materials compiled. All these mark the development of external medicine in modern age.

  13. UNIFORM ATTRACTOR FOR NONAUTONOMOUS INCOMPRESSIBLE NON-NEWTONIAN FLUID WITH A NEW CLASS OF EXTERNAL FORCES

    Institute of Scientific and Technical Information of China (English)

    Zhao Caidi; Jia Xiaolin; Yang Xinbo

    2011-01-01

    This paper is joint with [27].The authors prove in this article the existence and reveal its structure of uniform attractor for a two-dimensional nonautonomous incompressible non-Newtonian fluid with a new class of external forces.

  14. Free and Forced Vibrations of Periodic Multispan Beams

    OpenAIRE

    Liping Zhu; Isaac Elishakoff; Lin, Y.K.

    1994-01-01

    In this study, the following two topics are considered for uniform multispan beams of both finite and infinite lengths with rigid transversal and elastic rotational constraints at each support: (a) free vibration and the associated frequencies and mode shapes; (b) forced vibration under a convected harmonic loading. The concept of wave propagation in periodic structures of Brillouin is utilized to investigate the wave motion at periodic supports of a multispan beam. A dispersion equation and ...

  15. EXISTENCE OF INFINITE ENERGY SOLUTION TO THE INELASTIC BOLTZMANN EQUATION WITH EXTERNAL FORCE

    Institute of Scientific and Technical Information of China (English)

    Wei Jinbo; Zhang Xianwen

    2012-01-01

    In this paper,the Cauchy problem for the inelastic Boltzmann equation with external force is considered in the case of initial data with infinite energy.More precisely,under the assumptions on the bicharacteristic generated by external force,we prove the global existence of solution for small initial data compared to the local Maxwellian exp{-p|x-v|2},which has infinite mass and energy.

  16. Formation of Periodic Vortex Streets Driven by the Lorents Force

    OpenAIRE

    池端, 義人; 本地, 弘之; 杉原, 裕司

    1996-01-01

    Quasi-2D periodic vortex streets, driven by the Lorentz force due to the interaction of a localized magnetic field with an electrolytic current, have been investigated experimentally using a shallow water tank with a movable bottom floor. The vortex street formation has also been investigated numerically and some simulated flow patterns are presented.

  17. Recognition of resonance type in periodically forced oscillators

    NARCIS (Netherlands)

    Broer, H.W.; Holtman, S.J.; Vegter, G.

    2010-01-01

    This paper deals with families of periodically forced oscillators undergoing a Hopf-Neimarck-Sacker bifurcation. The interest is in the corresponding resonance sets, regions in parameter space for which subharmonics occur. It is a classical result that the local geometry of these sets in the non-deg

  18. Entropic transport without external force in confined channel with oscillatory boundary

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Department of Chemical Physics & Hefei National Laboratory for Physical Sciences at Microscales, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-12-28

    The dynamics of point-like Brownian particles in a periodic confined channel with oscillating boundaries has been studied. Directional transport (DT) behavior, characterized by net displacement along the horizontal direction, is observed even without external force which is necessary for the conventional DT where the boundaries are static. For typical parameter values, the average velocity V{sub t} of DT reaches a maximum with the variation of the noise intensity D, being alike to the phenomenon of stochastic resonance. Interestingly, we find that V{sub t} shows nontrivial dependences on the particle gravity G depending on the noise level. When the noise is large, V{sub t} increases monotonically with G indicating that heavier particle moves faster, while for small noise, V{sub t} shows a bell-shape dependence on G, suggesting that a particle with an intermediate weight may move the fastest. Such results were not observed for DT in a channel with static boundaries. To understand these findings, we have adopted an effective one-dimensional coarsening description, which facilitates us to introduce an effective entropic force along the horizontal direction. The average force is apparently nonzero due to the oscillatory boundary, hence leading to the net transport, and it shows similar dependences as V{sub t} on the noise intensity D and particle gravity G. The dependences of the DT behavior on other parameters describing the oscillatory channel have also been investigated, showing that DT is more pronounced for larger oscillation amplitude and frequency, and asymmetric geometry within a channel period and phase difference between neighboring periods are both necessary for the occurrence of DT.

  19. Forcing relation of non-Birkhoff periodic points in forced pendulum

    Science.gov (United States)

    Yamaguchi, Yoshihiro; Tanikawa, Kiyotaka

    Forced pendulums induce reversible non-montone twist mappings. Non-Birkhoff periodic orbits (NBO) are found in these mappings, hence in the pendulums. The existence of an NBO is equivalent with the non-integrability of the system. Two types of the forcing relation for NBOs are obtained.

  20. Recent drying of the Fertile Crescent: natural or externally forced?

    Science.gov (United States)

    Kelley, Colin

    2014-05-01

    There has been a reduction in observed precipitation over the greater Mediterranean region since the middle of the 20th Century. Recent studies suggest that while anthropogenic forcing has already begun to assert itself in recent decades, the preponderance of the winter drying trend is attributable to the large natural multidecadal variability of the North Atlantic Oscillation (NAO), while over the eastern Mediterranean, the anthropogenic, or forced drying signal is more clearly evident. This forced drying is projected to increase during the 21st Century according to the newest global climate models and this aridification would present significant challenges for a region that is already water-stressed. Although the Fertile Crescent is historically known for its agricultural prosperity, the severity and persistence of the recent multiyear drought in Syria, directly prior to the 2011 uprising there, leads us to ask whether this is evidence of emerging global warming influence. This drought exacerbated existing water insecurity, resulting in an agricultural collapse and a mass migration of rural drought refugees to the urban areas in Syria's west. This migration followed the previous influx of Iragi refugees and combined with strong natural population growth to place a severe strain on resources. Here we examine observations of precipitation and temperature, both gridded and stations, along with simulations and projections from the newest global climate models, to estimate the forced contribution to the recent Syrian drought, and assess the uncertainty in future drying according to the models. We find that this region has experienced a long-term downward trend in precipitation, and a concomitant increase in temperature, serving to further dry the soil, and in surface pressure. We find that the shift in the distributions of three-year running means of surface pressure and precipitation due to the forcing make severe events such as the recent Syrian drought several

  1. Transient Dynamics of Elastic Hele-Shaw Cell Due to External Forces with Application to Impulse Mitigation

    CERN Document Server

    Tulchinsky, Arie

    2015-01-01

    We study the transient dynamics of a viscous liquid contained in a narrow gap between a rigid surface and a parallel elastic plate. The elastic plate is deformed due to an externally applied time-varying pressure-field. We model the flow-field via the lubrication approximation, and the plate deformation by the Kirchhoff-Love plate theory. We obtain a self-similarity solution for the case of an external point force acting on the elastic plate. The pressure and deformation field during and after the application of the external force are derived and presented by closed form expressions. We examine a uniform external pressure acting on the elastic plate over a finite region and during a finite time period, similar to the viscous-elastic interaction time-scale. The interaction between elasticity and viscosity is shown to reduce by order of magnitude the pressure within the Hele-Shaw cell compared with the externally applied pressure, thus suggesting such configurations may be used for impact mitigation.

  2. Transverse forces on vortices in superfluids in a periodic potential

    Science.gov (United States)

    Sonin, E. B.

    2016-08-01

    The paper analyzes the transverse forces (the Magnus and the Lorentz forces) on vortices in superfluids put into periodic potentials at T =0 . The case of weak potential and the tight-binding limit described by the Bose-Hubbard model were addressed. The analysis was based on the balance of true momentum and quasimomentum. A special attention was paid to the superfluid close to the superfluid-insulator transition. In this area of the phase diagram the theory predicts the particle-hole symmetry line where the Magnus force changes sign with respect to that expected from the sign of velocity circulation. Our analysis has shown that the magnitude of the Magnus force is a continuous function at crossing the particle-hole symmetry line. This challenges the theory connecting the magnitude of the Magnus force with topological Chern numbers and predicting a jump at crossing this line. Disagreement is explained by the role of intrinsic pinning and guided vortex motion ignored in the topological approach. It is one more evidence that in general topological arguments are not sufficient for derivation of equations of vortex motion.

  3. The roles of external forcing and natural variability in global warming hiatuses

    Science.gov (United States)

    Zhang, Lei

    2016-11-01

    Global mean surface temperature (GMST) rising has slowed down since late 1990s, which is referred to as the global warming hiatus. There was another global warming hiatus event during 1940s-1960s. The roles of the external forcing and the natural variability in both global warming hiatuses are explored, using EOF analysis. The first two leading EOF modes of the 5-year running mean global sea surface temperature (SST) reflect the global warming scenario (EOF1) and the interdecadal Pacific oscillation (IPO)-like natural variability (EOF2), respectively. In observation, PC2 was in its positive phase (eastern Pacific cooling) during 1940s-1960s, which contributed to the previous warming hiatus. In addition, GMST trends are found to be negative during late 1950s and 1960s in most of the CMIP5 historical runs, which implies that the external forcing also contributed to the pause in the GMST rising. It is further demonstrated that it is the natural radiative forcing (volcanic forcing) that caused the drop-down of GMST in 1960s. The current global warming hiatus has been attributed to the eastern Pacific cooling/enhanced Pacific trade winds. It is shown that the PC2 switched to its positive phase in late 1990s, and hence the IPO-like natural variability made a contribution to the slowdown of GMST rising in the past decade. It is also found that the EOF1 mode (global warming mode) of the observed SST features a smaller warming in tropical Pacific compared to the Indian Ocean and the tropical Atlantic. Such inter-basin warming contrast, which is attributed to the "ocean thermostat" mechanism, has been suggested to contribute to the intensification of Pacific trade winds since late 1990s as well. Global warming hiatuses are also found in the future projections from CMIP5 models, and the spatial pattern of the SST trends during the warming-hiatus periods exhibits an IPO-like pattern, which resembles the observed SST trends since late 1990s.

  4. Trends and projections of Southern Hemisphere baroclinicity: the role of external forcing and impact on Australian rainfall

    Science.gov (United States)

    Frederiksen, Carsten S.; Frederiksen, Jorgen S.; Sisson, Janice M.; Osbrough, Stacey L.

    2016-07-01

    Changes in the characteristics of Southern Hemisphere (SH) storms, in all seasons, during the second half of the twentieth century, have been related to changes in the annual cycle of SH baroclinic instability. In particular, significant negative trends in baroclinic instability, as measured by the Phillips Criterion, have been found in the region of the climatological storm tracks; a zonal band of significant positive trends occur further poleward. Corresponding to this decrease/increase in baroclinic instability there is a decrease/increase in the growth rate of storm formation at these latitudes over this period, and in some cases a preference for storm formation further poleward than normal. Based on model output from a multi-model ensemble (MME) of coupled atmosphere-ocean general circulation models, it is shown that these trends are the result of external radiative forcing, including anthropogenic greenhouse gases, ozone, aerosols and land-use change. The MME is used in an analysis of variance method to separate the internal (natural) variability in the Phillips Criterion from influences associated with anomalous external radiative forcing. In all seasons, the leading externally forced mode has a significant trend and a loading pattern highly correlated with the pattern of trends in the Phillips Criterion. The covariance between the externally forced component of SH rainfall and the leading external mode strongly resembles the MME pattern of SH rainfall trends. A comparison between similar analyses of MME simulations using the second half of the twenty-first century of the Representative Concentration Pathways (RCP) RCP8.5 and RCP4.5 scenarios show that trends in the Phillips Criterion and rainfall are projected to continue and intensify under increasing anthropogenic greenhouse gas concentrations.

  5. Trends and projections of Southern Hemisphere baroclinicity: the role of external forcing and impact on Australian rainfall

    Science.gov (United States)

    Frederiksen, Carsten S.; Frederiksen, Jorgen S.; Sisson, Janice M.; Osbrough, Stacey L.

    2017-05-01

    Changes in the characteristics of Southern Hemisphere (SH) storms, in all seasons, during the second half of the twentieth century, have been related to changes in the annual cycle of SH baroclinic instability. In particular, significant negative trends in baroclinic instability, as measured by the Phillips Criterion, have been found in the region of the climatological storm tracks; a zonal band of significant positive trends occur further poleward. Corresponding to this decrease/increase in baroclinic instability there is a decrease/increase in the growth rate of storm formation at these latitudes over this period, and in some cases a preference for storm formation further poleward than normal. Based on model output from a multi-model ensemble (MME) of coupled atmosphere-ocean general circulation models, it is shown that these trends are the result of external radiative forcing, including anthropogenic greenhouse gases, ozone, aerosols and land-use change. The MME is used in an analysis of variance method to separate the internal (natural) variability in the Phillips Criterion from influences associated with anomalous external radiative forcing. In all seasons, the leading externally forced mode has a significant trend and a loading pattern highly correlated with the pattern of trends in the Phillips Criterion. The covariance between the externally forced component of SH rainfall and the leading external mode strongly resembles the MME pattern of SH rainfall trends. A comparison between similar analyses of MME simulations using the second half of the twenty-first century of the Representative Concentration Pathways (RCP) RCP8.5 and RCP4.5 scenarios show that trends in the Phillips Criterion and rainfall are projected to continue and intensify under increasing anthropogenic greenhouse gas concentrations.

  6. Malaria Vaccine Development and How External Forces Shape It: An Overview

    OpenAIRE

    Veronique Lorenz; Gabriele Karanis; Panagiotis Karanis

    2014-01-01

    The aim of this paper is to analyse the current status and scientific value of malaria vaccine approaches and to provide a realistic prognosis for future developments. We systematically review previous approaches to malaria vaccination, address how vaccine efforts have developed, how this issue may be fixed, and how external forces shape vaccine development. Our analysis provides significant information on the various aspects and on the external factors that shape malaria vaccine development...

  7. An active optimal control strategy of rotor vibrations using external forces

    Science.gov (United States)

    Zhu, W.; Castelazo, I.; Nelson, H. D.

    1989-01-01

    An active control strategy for lateral rotor vibrations using external forces is proposed. An extended state observer is used to reconstruct the full states and the unbalance distribution. An optimal controller which accommodates persistent unbalance excitation is derived with feedback of estimated states and unbalances. Numerical simulations were conducted for two separate four degree of freedom rotor systems. These simulations indicated that the proposed strategy can achieve almost complete vibration cancellation. This was shown to be true even when the number of external control forces was less than the system order so long as coordinate coupling was present. Both steady state and transient response at a constant speed are presented.

  8. Pull-in control due to Casimir forces using external magnetic fields

    CERN Document Server

    Esquivel-Sirvent, R; Cocoletzi, G H

    2009-01-01

    We present a theoretical calculation of the pull-in control in capacitive micro switches actuated by Casimir forces, using external magnetic fields. The external magnetic fields induces an optical anisotropy due to the excitation of magneto plasmons, that reduces the Casimir force. The calculations are performed in the Voigt configuration, and the results show that as the magnetic field increases the system becomes more stable. The detachment length for a cantilever is also calculated for a cantilever, showing that it increases with increasing magnetic field. At the pull-in separation, the stiffness of the system decreases with increasing magnetic field.

  9. Self-assembly of colloidal bands driven by a periodic external field

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, André S.; Araújo, Nuno A. M., E-mail: nmaraujo@fc.ul.pt; Telo da Gama, Margarida M. [Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, P-1749-016 Lisboa, Portugal and Centro de Física Teórica e Computacional, Universidade de Lisboa, P-1749-016 Lisboa (Portugal)

    2016-01-21

    We study the formation of bands of colloidal particles driven by periodic external fields. Using Brownian dynamics, we determine the dependence of the band width on the strength of the particle interactions and on the intensity and periodicity of the field. We also investigate the switching (field-on) dynamics and the relaxation times as a function of the system parameters. The observed scaling relations were analyzed using a simple dynamic density-functional theory of fluids.

  10. Self-assembly of colloidal bands driven by a periodic external field

    Science.gov (United States)

    Nunes, André S.; Araújo, Nuno A. M.; Telo da Gama, Margarida M.

    2016-01-01

    We study the formation of bands of colloidal particles driven by periodic external fields. Using Brownian dynamics, we determine the dependence of the band width on the strength of the particle interactions and on the intensity and periodicity of the field. We also investigate the switching (field-on) dynamics and the relaxation times as a function of the system parameters. The observed scaling relations were analyzed using a simple dynamic density-functional theory of fluids.

  11. External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction.

    Science.gov (United States)

    Yang, Jian; Cong, Weijian; Chen, Yang; Fan, Jingfan; Liu, Yue; Wang, Yongtian

    2014-02-21

    The clinical value of the 3D reconstruction of a coronary artery is important for the diagnosis and intervention of cardiovascular diseases. This work proposes a method based on a deformable model for reconstructing coronary arteries from two monoplane angiographic images acquired from different angles. First, an external force back-projective composition model is developed to determine the external force, for which the force distributions in different views are back-projected to the 3D space and composited in the same coordinate system based on the perspective projection principle of x-ray imaging. The elasticity and bending forces are composited as an internal force to maintain the smoothness of the deformable curve. Second, the deformable curve evolves rapidly toward the true vascular centerlines in 3D space and angiographic images under the combination of internal and external forces. Third, densely matched correspondence among vessel centerlines is constructed using a curve alignment method. The bundle adjustment method is then utilized for the global optimization of the projection parameters and the 3D structures. The proposed method is validated on phantom data and routine angiographic images with consideration for space and re-projection image errors. Experimental results demonstrate the effectiveness and robustness of the proposed method for the reconstruction of coronary arteries from two monoplane angiographic images. The proposed method can achieve a mean space error of 0.564 mm and a mean re-projection error of 0.349 mm.

  12. Signal Processing in Periodically Forced Gradient Frequency Neural Networks.

    Science.gov (United States)

    Kim, Ji Chul; Large, Edward W

    2015-01-01

    Oscillatory instability at the Hopf bifurcation is a dynamical phenomenon that has been suggested to characterize active non-linear processes observed in the auditory system. Networks of oscillators poised near Hopf bifurcation points and tuned to tonotopically distributed frequencies have been used as models of auditory processing at various levels, but systematic investigation of the dynamical properties of such oscillatory networks is still lacking. Here we provide a dynamical systems analysis of a canonical model for gradient frequency neural networks driven by a periodic signal. We use linear stability analysis to identify various driven behaviors of canonical oscillators for all possible ranges of model and forcing parameters. The analysis shows that canonical oscillators exhibit qualitatively different sets of driven states and transitions for different regimes of model parameters. We classify the parameter regimes into four main categories based on their distinct signal processing capabilities. This analysis will lead to deeper understanding of the diverse behaviors of neural systems under periodic forcing and can inform the design of oscillatory network models of auditory signal processing.

  13. Symmetries, conservation laws, and time reversibility for Hamiltonian systems with external forces

    NARCIS (Netherlands)

    Schaft, A.J. van der

    1983-01-01

    A system theoretic framework is given for the description of Hamiltonian systems with external forces and partial observations of the state. It is shown how symmetries and conservation laws can be defined within this framework. A generalization of Noether's theorem is obtained. Finally a precise def

  14. Real-Time Control of Humanoid Robots Considering External Forces on Upper Part of the Body

    Science.gov (United States)

    Inomata, Kentaro; Shigemori, Yo; Uchimura, Yutaka

    Recently, the demand for the practical use of service robots has risen significantly because of acceleration of demographic aging, and a humanoid robot is one of the promising form factors of service robots. When a humanoid robot is used by a human in a real environment, the robot needs to be designed by taking into account the various external forces that act on the robot. Thus far, most of the walking humanoid robots have been mainly controlled by the conventional ZMP method to maintain a stable walking posture. However, the conventional ZMP method can not be used to handle the various external forces that act on the upper part of the humanoid robot body. To overcome these problems, in this paper, we propose a novel control method, which we called 3DZMP and pZMP, for a humanoid robot to react to the external force on the upper part of the body. The 3DZMP is defined as the point in three-dimensional space at which the moment about all axes is zero. 3DZMP can prevent the rotation of a humanoid robot. The pZMP is defined as the point corresponding to the orthographic projection of the 3DZMP on a plane. pZMP is used to evaluate the stability of 3DZMP. We implemented the proposed method on a prototype robot and verified that the robot gained the capability to react to external forces that could not be handled by the conventional ZMP method.

  15. A piecewise-integration method for simulating the influence of external forcing on climate

    Institute of Scientific and Technical Information of China (English)

    Zhifu Zhang; Chongjian Qiu; Chenghai Wang

    2008-01-01

    Climate drift occurs in most general circulation models (GCMs) as a result of incomplete physical and numerical representation of the complex climate system,which may cause large uncertainty in sensitivity experiments evaluating climate response to changes in external forcing.To solve this problem,we propose a piecewise-integration method to reduce the systematic error in climate sensitivity studies.The observations are firstly assimilated into a numerical model by using the dynamic relaxation technique to relax to the current state of atmosphere,and then the assimilated fields are continuously used to reinitialize the simulation to reduce the error of climate simulation.When the numerical model is integrated with changed external forcing,the results can be split into two parts,background and perturbation fields,and the background is the state before the external forcing is changed.The piecewise-integration method is used to continuously reinitialize the model with the assimilated field,instead of the background.Therefore,the simulation error of the model with the external forcing can be reduced.In this way,the accuracy of climate sensitivity experiments is greatly improved.Tests with a simple low-order spectral model show that this approach can significantly reduce the uncertainty of climate sensitivity experiments.

  16. Materials Bound by Non-Chemical Forces: External Fields and the Quantum Vacuum

    CERN Document Server

    Swain, John; Srivastava, Yogendra

    2014-01-01

    We discuss materials which owe their stability to external fields. These include: 1) external electric or magnetic fields, and 2) quantum vacuum fluctuations in these fields induced by suitable boundary conditions (the Casimir effect). Instances of the first case include the floating water bridge and ferrofluids in magnetic fields. An example of the second case is taken from biology where the Casimir effect provides an explanation of the formation of stacked aggregations or "rouleaux" by negatively charged red blood cells. We show how the interplay between electrical and Casimir forces can be used to drive self-assembly of nano-structured materials, and could be generalized both as a probe of Casimir forces and as a means of manufacturing nanoscale structures. Interestingly, all the cases discussed involve the generation of the somewhat exotic negative pressures. We note that very little is known about the phase diagrams of most materials in the presence of external fields other than those represented by the ...

  17. Phase Synchronization as a Mechanism of Controlling Spatiotemporal Chaos via External Periodic Signal

    Institute of Scientific and Technical Information of China (English)

    SANG Hai-Bo; HE Kai-Fen

    2004-01-01

    @@ We find that phase synchronization (PS) is a mechanism in which the spatiotemporal chaos (STC) can be suppressed to a spatially regular (SR) state by applying an external periodic signal in a one-dimensional driven drift-wave system. In the driving wave coordinate, the nonlinear system can be transformed to a set of coupled oscillators moving in a periodic potential. In this multi-dimensional system, the internal modes are slaved one by one through PS by the control signal. Two types of responses of the internal modes to the external periodic signal are observed. For some modes, the stabilization is through frequency-locking; while for the other modes,a special kind of PS without frequency-locking, namely multi-looping PS, is developed.

  18. A computational vector-map model of neonate saccades: modulating the externality effect through refraction periods.

    Science.gov (United States)

    Jansen, Peter A; Fiacconi, Chris M; Gibson, Laura C

    2010-11-23

    The present study develops an explicit and predictive computational model of neonate saccades based on the interaction of several simple mechanisms, including the tendency to fixate towards areas of high contrast, and the decay and recovery of a world-centered contrast representation simulating a low-level inhibition of return mechanism. Emergent properties similar to early visual behaviors develop, including the externality effect (or tendency to focus on external then internal features). The age-associated progression of this effect is modulated by the decay period of the model's contrast representation, where the high-level behavior of either scanning broadly or locally is modulated by a single decay parameter.

  19. Fingerprints in the clouds: identifying expected cloud responses to external forcing

    Science.gov (United States)

    Marvel, K.; Zelinka, M. D.

    2013-12-01

    Changes in cloud properties in response to external forcing affect the radiation budget of the Earth, which in turn affects the equilibrium climate response. Reconciling modeled and observed cloud trends is therefore crucial in understanding climate sensitivity and the response to anthropogenic increases in greenhouse gas concentrations. While cloud responses differ greatly across models, errors in the locations of large-scale features can obscure even those physical processes that are robust across multiple models. We propose a method to track changes in cloud height, amount, and vertical profile across multiple models, and show that certain characteristics of the response are present in most models. This allows us to calculate a multidimensional fingerprint representing the characteristic cloud response to external forcing. We show how this fingerprint changes when various relevant forcing terms are included or excluded, and differentiate between models with high and low climate sensitivities. This represents an important first step toward detection and attribution of cloud trends.

  20. External forces influence the elastic coupling effects during cargo transport by molecular motors.

    Science.gov (United States)

    Berger, Florian; Keller, Corina; Klumpp, Stefan; Lipowsky, Reinhard

    2015-02-01

    Cellular transport is achieved by the cooperative action of molecular motors which are elastically linked to a common cargo. When the motors pull on the cargo at the same time, they experience fluctuating elastic strain forces induced by the stepping of the other motors. These elastic coupling forces can influence the motors' stepping and unbinding behavior and thereby the ability to transport cargos. Based on a generic single motor description, we introduce a framework that explains the response of two identical molecular motors to a constant external force. In particular, we relate the single motor parameters, the coupling strength and the external load force to the dynamics of the motor pair. We derive four distinct transport regimes and determine how the crossover lines between the regimes depend on the load force. Our description of the overall cargo dynamics takes into account relaxational displacements of the cargo caused by the unbinding of one motor. For large forces and weak elastic coupling these back-shifts dominate the displacements. To develop an intuitive understanding about motor cooperativity during cargo transport, we introduce a time scale for load sharing. This time scale allows us to predict how the regulation of single motor parameters influences the cooperativity. As an example, we show that up-regulating the single motor processivity enhances load sharing of the motor pair.

  1. Extracavity and external cavity second-harmonic generation in a periodically poled silica fibre

    Science.gov (United States)

    Dontsova, E. I.; Kablukov, S. I.; Lobach, I. A.; Dostovalov, A. V.; Babin, S. A.; Gladyshev, A. V.; Dianov, E. M.; Corbary, C.; Ibsen, M.; Kazansky, P. G.

    2016-11-01

    We have studied second-harmonic generation (SHG) of a cw single-frequency ytterbium-doped fibre laser, using a periodically poled silica fibre as a nonlinear medium for frequency conversion. All-fibre external cavity SHG has been investigated for the first time. A twofold increase in second-harmonic power in a fibre ring cavity has been demonstrated and possibilities of further optimising the fibre scheme have been analysed.

  2. Active contour external force using vector field convolution for image segmentation.

    Science.gov (United States)

    Li, Bing; Acton, Scott T

    2007-08-01

    Snakes, or active contours, have been widely used in image processing applications. Typical roadblocks to consistent performance include limited capture range, noise sensitivity, and poor convergence to concavities. This paper proposes a new external force for active contours, called vector field convolution (VFC), to address these problems. VFC is calculated by convolving the edge map generated from the image with the user-defined vector field kernel. We propose two structures for the magnitude function of the vector field kernel, and we provide an analytical method to estimate the parameter of the magnitude function. Mixed VFC is introduced to alleviate the possible leakage problem caused by choosing inappropriate parameters. We also demonstrate that the standard external force and the gradient vector flow (GVF) external force are special cases of VFC in certain scenarios. Examples and comparisons with GVF are presented in this paper to show the advantages of this innovation, including superior noise robustness, reduced computational cost, and the flexibility of tailoring the force field.

  3. Free and Forced Vibrations of Periodic Multispan Beams

    Directory of Open Access Journals (Sweden)

    Liping Zhu

    1994-01-01

    Full Text Available In this study, the following two topics are considered for uniform multispan beams of both finite and infinite lengths with rigid transversal and elastic rotational constraints at each support: (a free vibration and the associated frequencies and mode shapes; (b forced vibration under a convected harmonic loading. The concept of wave propagation in periodic structures of Brillouin is utilized to investigate the wave motion at periodic supports of a multispan beam. A dispersion equation and its asymptotic form is obtained to determine the natural frequencies. For the special case of zero rotational spring stiffness, an explicit asymptotic expression for the natural frequency is also given. New expressions for the mode shapes are obtained in the complex form for multispan beams of both finite and infinite lengths. The orthogonality conditions of the mode shapes for two cases are formulated. The exact responses of both finite and infinite span beams under a convected harmonic loading are obtained. Thus, the position and the value of each peak in the harmonic response function can be determined precisely, as well as the occurrence of the so-called coincidence phenomenon, when the response is greatly enhanced.

  4. Force assessment in periodic paralysis after electrical muscle stimulation.

    Science.gov (United States)

    Day, John W; Sakamoto, Carl; Parry, Gareth J; Lehmann-Horn, Frank; Iaizzo, Paul A

    2002-03-01

    To obtain an objective measure of muscle force in periodic paralysis, we studied ankle dorsiflexion torque during induced paralytic attacks in hyperkalemic and hypokalemic patients. SUBJECTS, PATIENTS, AND METHODS: Dorsiflexor torque after peroneal nerve stimulation was recorded during provocative tests on 5 patients with hypokalemic or hyperkalemic disorders and on 2 control subjects (1995-2001). Manual strength assessment was simultaneously performed in a blinded fashion. Standardized provocation procedures were used. The loss of torque in hyperkalemic patients roughly paralleled the loss of clinically detectable strength, whereas in the hypokalemic patients, pronounced torque loss occurred well before observed clinical effects. No dramatic changes occurred in the control subjects. Torque amplitude decreased more than 70% in all patients during the provocation tests; such decreases were associated with alterations induced in serum potassium concentrations. Stimulated torque measurement offers several advantages in characterizing muscle dysfunction in periodic paralysis: (1) it is independent of patient effort; (2) it can show a definitely abnormal response early during provocative maneuvers; and (3) characteristics of muscle contraction can be measured that are unobservable during voluntary contraction. Stimulated torque measurements can characterize phenotypic muscle function in neuromuscular diseases.

  5. Long-period astronomical forcing of mammal turnover.

    Science.gov (United States)

    van Dam, Jan A; Abdul Aziz, Hayfaa; Alvarez Sierra, M Angeles; Hilgen, Frederik J; van den Hoek Ostende, Lars W; Lourens, Lucas J; Mein, Pierre; van der Meulen, Albert J; Pelaez-Campomanes, Pablo

    2006-10-12

    Mammals are among the fastest-radiating groups, being characterized by a mean species lifespan of the order of 2.5 million years (Myr). The basis for this characteristic timescale of origination, extinction and turnover is not well understood. Various studies have invoked climate change to explain mammalian species turnover, but other studies have either challenged or only partly confirmed the climate-turnover hypothesis. Here we use an exceptionally long (24.5-2.5 Myr ago), dense, and well-dated terrestrial record of rodent lineages from central Spain, and show the existence of turnover cycles with periods of 2.4-2.5 and 1.0 Myr. We link these cycles to low-frequency modulations of Milankovitch oscillations, and show that pulses of turnover occur at minima of the 2.37-Myr eccentricity cycle and nodes of the 1.2-Myr obliquity cycle. Because obliquity nodes and eccentricity minima are associated with ice sheet expansion and cooling and affect regional precipitation, we infer that long-period astronomical climate forcing is a major determinant of species turnover in small mammals and probably other groups as well.

  6. Controlled structuring of binary hard-disk mixtures via a periodic, external potential.

    Science.gov (United States)

    Franzrahe, K; Nielaba, P

    2009-05-01

    Ordering phenomena on surfaces or in monolayers can be successfully studied by model systems as binary hard-disk mixtures, the influence of a substrate being modeled by an external potential. For the field-free case the thermodynamic stability of space-filling lattice structures for binary hard-disk mixtures is studied by Monte Carlo computer simulations. As these structures prove to be thermodynamically stable only in high pressure environments, the phase behavior of an equimolar binary mixture with a diameter ratio of sigma_{B}/sigma_{A}=0.414 exposed to an external, one-dimensional, periodic potential is analyzed in detail. The underlying ordering mechanisms and the resulting order differ considerably, depending on which components of the mixture interact with the external potential. The simulations show that slight deviations in the concentration of large particles x_{A} or the diameter ratio sigma_{B}/sigma_{A} have no impact on the occurrence of the various field-induced phenomena as long as the mixture stays in the relevant regime of the packing fraction eta . Furthermore the importance of the commensurability of the external potential to the S1(AB) square lattice for the occurrence of the induced ordering is discussed.

  7. Propagation of the state change induced by external forces in local interactions

    Science.gov (United States)

    Lu, Jianjun; Tokinaga, Shozo

    2016-10-01

    This paper analyses the propagation of the state changes of agents that are induced by external forces applied to a plane. In addition, we propose two models for the behavior of the agents placed on a lattice plane, both of which are affected by local interactions. We first assume that agents are allowed to move to another site to maximise their satisfaction. Second, we utilise a model in which the agents choose activities on each site. The results show that the migration (activity) patterns of agents in both models achieve stability without any external forces. However, when we apply an impulsive external force to the state of the agents, we then observe the propagation of the changes in the agents' states. Using simulation studies, we show the conditions for the propagation of the state changes of the agents. We also show the propagation of the state changes of the agents allocated in scale-free networks and discuss the estimation of the agents' decisions in real state changes. Finally, we discuss the estimation of the agents' decisions in real state temporal changes using economic and social data from Japan and the United States.

  8. Hydrodynamic Forces on Macromolecules Protruding from Lipid Bilayers Due to External Liquid Flows.

    Science.gov (United States)

    Jönsson, Peter; Jönsson, Bengt

    2015-11-24

    It has previously been observed that an externally applied hydrodynamic shear flow above a fluid lipid bilayer can change the local concentration of macromolecules that are associated with the lipid bilayer. The external liquid flow results in a hydrodynamic force on molecules protruding from the lipid bilayer, causing them to move in the direction of the flow. However, there has been no quantitative study about the magnitude of these forces. We here use finite element simulations to investigate how the magnitude of the external hydrodynamic forces varies with the size and shape of the studied macromolecule. The simulations show that the hydrodynamic force is proportional to the effective hydrodynamic area of the studied molecule, Ahydro, multiplied by the mean hydrodynamic shear stress acting on the membrane surface, σhydro. The parameter Ahydro depends on the size and shape of the studied macromolecule above the lipid bilayer and scales with the cross-sectional area of the molecule. We also investigate how hydrodynamic shielding from other surrounding macromolecules decreases Ahydro when the surface coverage of the shielding macromolecules increases. Experiments where the protein streptavidin is anchored to a supported lipid bilayer on the floor of a microfluidic channel were finally performed at three different surface concentrations, Φ = 1%, 6%, and 10%, where the protein is being moved relative to the lipid bilayer by a liquid flow through the channel. From photobleaching measurements of fluorescently labeled streptavidin we found the experimental drift data to be within good accuracy of the simulated results, less than 12% difference, indicating the validity of the results obtained from the simulations. In addition to giving a deeper insight into how a liquid flow can affect membrane-associated molecules in a lipid bilayer, we also see an interesting potential of using hydrodynamic flow experiments together with the obtained results to study the size and

  9. Temperature response to external forcing in simulations and reconstructions of the last millennium

    Directory of Open Access Journals (Sweden)

    L. Fernández-Donado

    2012-08-01

    Full Text Available The understanding of natural climate variability and its driving factors is crucial to assess future climate change. Therefore, comparing proxy-based climate reconstructions with forcing factors as well as comparing these with paleoclimate model simulations is key to gain insights into the relative roles of internal versus forced variability. A review of the state of modeling of the last millennium climate previous to the CMIP5-PMIP3 coordinated effort is presented and compared to the available temperature reconstructions. Simulations and reconstructions broadly agree on reproducing the major temperature changes and suggest an overall linear response to external forcing on multidecadal or longer timescales. Internal variability is found to have an important influence at hemispheric and global scales. The spatial distribution of simulated temperature changes during the transition of the Medieval Climate Anomaly to the Little Ice Age disagrees with that found in the reconstructions, thus advocating for internal variability as a possible major player in shaping temperature changes through the millennium.

    A paleo transient climate response (PTCR is defined to provide a quantitative framework for analysing the consistency between simulated and reconstructed climate. Beyond an overall agreement between simulated and reconstructed PTCR ranges, this analysis is able to single out specific discrepancies between some reconstructions and the ensemble of simulations. The disagreement is found in the cases where the reconstructions show reduced covariability with external forcings or when they present high rates of temperature change.

  10. Random walk with nonuniform angular distribution biased by an external periodic pulse

    Science.gov (United States)

    Acharyya, Aranyak

    2016-11-01

    We studied the motion of a random walker in two dimensions with nonuniform angular distribution biased by an external periodic pulse. Here, we analytically calculated the mean square displacement (end-to-end distance of a walk after n time steps), without bias and with bias. We determined the average x-component of the final displacement of the walker. Interestingly, we noted that for a particular periodicity of the bias, this average x-component of the final displacement becomes approximately zero. The average y-component of the final displacement is found to be zero for any perodicity of the bias, and its reason can be attributed to the nature of the probability density function of the angle (subtended by the displacement vector with the x-axis). These analytical results are also supported by computer simulations. The present study may be thought of as a model for arresting the bacterial motion (along a preferred direction) by an external periodic bias. This article will be useful for undergraduate students of physics, statistics and biology as an example of an interdisciplinary approach to understand a way to control bacterial motion.

  11. Determination of External Forces in Alpine Skiing Using a Differential Global Navigation Satellite System

    Directory of Open Access Journals (Sweden)

    Erich Müller

    2013-08-01

    Full Text Available In alpine ski racing the relationships between skier kinetics and kinematics and their effect on performance and injury-related aspects are not well understood. There is currently no validated system to determine all external forces simultaneously acting on skiers, particularly under race conditions and throughout entire races. To address the problem, this study proposes and assesses a method for determining skier kinetics with a single lightweight differential global navigation satellite system (dGNSS. The dGNSS kinetic method was compared to a reference system for six skiers and two turns each. The pattern differences obtained between the measurement systems (offset ± SD were −26 ± 152 N for the ground reaction force, 1 ± 96 N for ski friction and −6 ± 6 N for the air drag force. The differences between turn means were small. The error pattern within the dGNSS kinetic method was highly repeatable and precision was therefore good (SD within system: 63 N ground reaction force, 42 N friction force and 7 N air drag force allowing instantaneous relative comparisons and identification of discriminative meaningful changes. The method is therefore highly valid in assessing relative differences between skiers in the same turn, as well as turn means between different turns. The system is suitable to measure large capture volumes under race conditions.

  12. Exact periodic and solitonic states of the spinor condensates in a uniform external potential

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhi-Hai [School of Physics and Electronics, Yancheng Teachers University, Yancheng 224051 (China); Yang, Shi-Jie, E-mail: yangshijie@tsinghua.org.cn [Department of Physics, Beijing Normal University, Beijing 100875 (China)

    2016-08-15

    We propose a method to analytically solve the one-dimensional coupled nonlinear Gross–Pitaevskii equations which govern the motion of the spinor Bose–Einstein condensates. In a uniform external potential, several classes of exact periodic and solitonic solutions, either in real or in complex forms, are obtained for both the F=1 and F=2 condensates for the Hamiltonian comprising the kinetic energy, the linear and the quadratic Zeeman energies. Real solutions take the form of composite soliton trains. Complex solutions correspond to the mass counter-flows as well as spin currents. These solutions are general that contains neither approximations nor constraints on the system parameters.

  13. Streamwise-body-force-model for rapid simulation combining internal and external flow fields

    Directory of Open Access Journals (Sweden)

    Cui Rong

    2016-10-01

    Full Text Available A streamwise-body-force-model (SBFM is developed and applied in the overall flow simulation for the distributed propulsion system, combining internal and external flow fields. In view of axial stage effects, fan or compressor effects could be simplified as body forces along the streamline. These body forces which are functions of local parameters could be added as source terms in Navier-Stokes equations to replace solid boundary conditions of blades and hubs. The validation of SBFM with uniform inlet and distortion inlet of compressors shows that pressure performance characteristics agree well with experimental data. A three-dimensional simulation of the integration configuration, via a blended wing body aircraft with a distributed propulsion system using the SBFM, has been completed. Lift coefficient and drag coefficient agree well with wind tunnel test results. Results show that to reach the goal of rapid integrated simulation combining internal and external flow fields, the computational fluid dynamics method based on SBFM is reasonable.

  14. Structures of Equatorial Envelope Rossby Wave Under a Generalized External Forcing

    Institute of Scientific and Technical Information of China (English)

    FUZun-Tao; LIUShi-Da; LIUShi-Kuo

    2004-01-01

    The cubic nonlinear Schroedinger (NLS for short) equation with a generalized external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial cnvelope Rossby waves are obtained with the help of a new transformation, Jacobi elliptic functions,and elliptic equation. It is shown that different types of resonant phase-locked diabatic heating play different roles in structures of equatorial envelope Rossby wave.

  15. Structures of Equatorial Envelope Rossby Wave Under a Generalized External Forcing

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Da; LIU Shi-Kuo

    2004-01-01

    The cubic nonlinear Schrodinger (NLS for short) equation with a generalized external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial envelope Rossby waves are obtained with the help of a new transformation, Jacobi elliptic functions,and elliptic equation. It is shown that different types of resonant phase-locked diabatic heating play different roles in structures of equatorial envelope Rossby wave.

  16. A Digital Map From External Forcing to the Final Surface Warming Pattern and its Seasonal Cycle

    Science.gov (United States)

    Cai, M.

    2015-12-01

    Historically, only the thermodynamic processes (e.g., water vapor, cloud, surface albedo, and atmospheric lapse rate) that directly influence the top of the atmosphere (TOA) radiative energy flux balance are considered in climate feedback analysis. One of my recent research areas is to develop a new framework for climate feedback analysis that explicitly takes into consideration not only the thermodynamic processes that the directly influence the TOA radiative energy flux balance but also the local dynamical (e.g., evaporation, surface sensible heat flux, vertical convections etc) and non-local dynamical (large-scale horizontal energy transport) processes in aiming to explain the warming asymmetry between high and low latitudes, between ocean and land, and between the surface and atmosphere. In the last 5-6 years, we have developed a coupled atmosphere-surface climate feedback-response analysis method (CFRAM) as a new framework for estimating climate feedback and sensitivity in coupled general circulation models with a full physical parameterization package. In the CFRAM, the isolation of partial temperature changes due to an external forcing alone or an individual feedback is achieved by solving the linearized infrared radiation transfer model subject to individual energy flux perturbations (external or due to feedbacks). The partial temperature changes are addable and their sum is equal to the (total) temperature change (in the linear sense). The CFRAM is used to isolate the partial temperature changes due to the external forcing, due to water vapor feedback, clouds, surface albedo, local vertical convection, and non-local atmospheric dynamical feedbacks, as well as oceanic heat storage. It has been shown that seasonal variations in the cloud feedback, surface albedo feedback, and ocean heat storage/dynamics feedback, directly caused by the strong annual cycle of insolation, contribute primarily to the large seasonal variation of polar warming. Furthermore, the

  17. EXTERNAL FORCES DRIVING CHANGE IN THE ROMANIAN SMALL AND MEDIUM SIZED ENTERPRISES

    Directory of Open Access Journals (Sweden)

    Roiban Roxana Nadina

    2012-07-01

    Full Text Available Change is a constant in everyday life confronting organizations to continuously adapt their strategy, structure, processes, and culture in order to survive and stay competitive on the market. Implementing organizational change is one of the most important skills required for managers and in the meantime the most difficult one. The forces driving change within an organization, that can be either external or internal, are those that propel a company forward towards change and in order to identify the need for change and make the proper changes, managers have to develop a tool that allows them to analyze how does the environment influence their business activities. A vision for change will clarify the directions in which the organization needs to move, starting from its current state and taking in consideration the existing opportunities and threats from the environment that allow to move to a future desired state. The purpose of this paper is to identify the concern for change in the Romanian small and medium sized enterprises by presenting and explaining the past and present influences of the main external forces that have determined the need for change in the last 3-5 years and to make recommendations about future possible changes that have to be performed by managers for a better harmonization with the environment. The research method used for this study is the interview on a sample that contains some of the most relevant SME’s from the western side of Romania, from different industries. We analyzed the main external forces that had an impact on the small and medium sized enterprises and how were they generating the need for organizational change, in order to see which present and future changes are required.

  18. A Stability Criterion for Time-Delay Tension Leg Platform Systems Subjected to External Force

    Institute of Scientific and Technical Information of China (English)

    Chen-Yuan CHEN; Chien-wen SHEN; Cheng-Wu CHEN; Kevin Fong-Rey LIU; Ming-Jen CHENG

    2009-01-01

    Stability analysis plays a central role in nonlinear system theory and engineering application.Over the past few yeats,the stability analysis of fuzzy systems has been proposed and there are many successful applications in practical engineering.Therefore,in this paper firstly proposed is the stability analysis on oceanic structure by fuzzy models.In the present study,Takagi-Sugeno (T-S) fuzzy model is proposed for a time delay tension leg platform (TLP) system subjected to an external wave force.In terms of stability analysis,linear matrix inequality (LMI) conditions are derived via Lyapunov theory to guarantee the stability of the TLP system.

  19. A simple method to construct soliton-like solution of the general KdV equation with external force

    Institute of Scientific and Technical Information of China (English)

    JiefangZHANG; FengminWU

    2000-01-01

    A simple and direct method is described to construct the soliton-like solution for the general KdV equation with external force. Crucial to the method is the assumption that the solution chosen is a special truncated expansion.

  20. Study of deformation of droplet in external force field by using liquid-gas model of lattice-gas

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, Ken-ichi; Watanabe, Tadashi [Japan Atomic Energy Research Inst., Center for Promotion of Computational Science and Engineering, Tokai, Ibaraki (Japan)

    2000-10-01

    The deformation of the droplet by the external force which is assumed to be gravity is studied by using the liquid-gas model of lattice-gas. Two types of liquid-gas models, one is the minimal model and the other is the maximal model, which are distinguished from each other by the added long-range interactions are used for the simulation of the droplet deformation. The difference of the droplet deformation between the maximal model and the minimal model was observed. While the droplet of the minimal model elongates in the direction of the external force, the droplet of the maximal model elongates in the perpendicular direction to the external force. Therefore the droplet deformation in the external force field of the maximal model is more similar to the droplet deformation which is observed in experiments than that of the minimal model. (author)

  1. Influence of an external magnetic field on forced turbulence in a swirling flow of liquid metal

    CERN Document Server

    Gallet, Basile; Mordant, Nicolas

    2009-01-01

    We report an experimental investigation on the influence of an external magnetic field on forced 3D turbulence of liquid gallium in a closed vessel. We observe an exponential damping of the turbulent velocity fluctuations as a function of the interaction parameter N (ratio of Lorentz force over inertial terms of the Navier-Stokes equation). The flow structures develop some anisotropy but do not become bidimensional. From a dynamical viewpoint, the damping first occurs homogeneously over the whole spectrum of frequencies. For larger values of N, a very strong additional damping occurs at the highest frequencies. However, the injected mechanical power remains independent of the applied magnetic field. The simultaneous measurement of induced magnetic field and electrical potential differences shows a very weak correlation between magnetic field and velocity fluctuations. The observed reduction of the fluctuations is in agreement with a previously proposed mechanism for the saturation of turbulent dynamos and wit...

  2. Two-Dimensional Analytical Solution of the Laminar Forced Convection in a Circular Duct with Periodic Boundary Condition

    Directory of Open Access Journals (Sweden)

    M. R. Astaraki

    2012-01-01

    Full Text Available In the present study analytical solution for forced convection heat transfer in a circular duct with a special boundary condition has been presented, because the external wall temperature is a periodic function of axial direction. Local energy balance equation is written with reference to the fully developed regime. Also governing equations are two-dimensionally solved, and the effect of duct wall thickness has been considered. The temperature distribution of fluid and solid phases is assumed as a periodic function of axial direction and finally temperature distribution in the flow field, solid wall, and local Nusselt number, is obtained analytically.

  3. Analysis of Externality of Rural Labor Force Flow in Central and Western Regions of China and Benefit Compensation

    Institute of Scientific and Technical Information of China (English)

    Xin; LI; Haijing; HU

    2013-01-01

    According to the theories of institutional economics and development economics,the positive and negative externality of rural labor force flowing from central and western regions and into eastern regions of China were analyzed,and then it was proposed that it is necessary to positive externality,rather than take"household register"measures to solve the problem simply.

  4. Bidirectional transport by molecular motors: enhanced processivity and response to external forces.

    Science.gov (United States)

    Müller, Melanie J I; Klumpp, Stefan; Lipowsky, Reinhard

    2010-06-02

    Intracellular transport along cytoskeletal filaments is often mediated by two teams of molecular motors that pull on the same cargo and move in opposite directions along the filaments. We have recently shown theoretically that this bidirectional transport can be understood as a stochastic tug-of-war between the two motor teams. Here, we further develop our theory to investigate the experimentally accessible dynamic behavior of cargos transported by strong motors such as kinesin-1 or cytoplasmic dynein. By studying the run and binding times of such a cargo, we show that the properties of biological motors, such as the large ratio of stall/detachment force and the small ratio of superstall backward/forward velocity, are favorable for bidirectional cargo transport, leading to fast motion and enhanced diffusion. In addition, cargo processivity is shown to be strongly enhanced by transport via several molecular motors even if these motors are engaged in a tug-of-war. Finally, we study the motility of a bidirectional cargo under force. Frictional forces arising, e.g., from the viscous cytoplasm, lead to peaks in the velocity distribution, while external forces as exerted, e.g., by an optical trap, lead to hysteresis effects. Our results, in particular our explicit expressions for the cargo binding time and the distance of the peaks in the velocity relation under friction, are directly accessible to in vitro as well as in vivo experiments.

  5. External Load Affects Ground Reaction Force Parameters Non-uniformly during Running in Weightlessness

    Science.gov (United States)

    DeWitt, John; Schaffner, Grant; Laughlin, Mitzi; Loehr, James; Hagan, R. Donald

    2004-01-01

    Long-term exposure to microgravity induces detrimefits to the musculcskdetal system (Schneider et al., 1995; LeBlanc et al., 2000). Treadmill exercise is used onboard the International Space Station as an exercise countermeasure to musculoskeletal deconditioning due to spaceflight. During locomotive exercise in weightlessness (0G), crewmembers wear a harness attached to an external loading mechanism (EL). The EL pulls the crewmember toward the treadmill, and provides resistive load during the impact and propulsive phases of gait. The resulting forces may be important in stimulating bone maintenance (Turner, 1998). The EL can be applied via a bungee and carabineer clip configuration attached to the harness and can be manipulated to create varying amounts of load levels during exercise. Ground-based research performed using a vertically mounted treadmill found that peak ground reaction forces (GRF) during running at an EL of less than one body weight (BW) are less than those that occur during running in normal gravity (1G) (Davis et al., 1996). However, it is not known how the GRF are affected by the EL in a true OG environment. Locomotion while suspended may result in biomechanics that differ from free running. The purpose of this investigation was to determine how EL affects peak impact force, peak propulsive force, loading rate, and impulse of the GRF during running in 0G. It was hypothesized that increasing EL would result in increases in each GRF parameter.

  6. The External Periodic Influence Effect on the Kinetics of Metals Fragmentationduring the Severe Plastic Deformation

    Directory of Open Access Journals (Sweden)

    A.V. Khomenko

    2015-03-01

    Full Text Available Using the Landau theory of phase transitions, the solids fragmentation during the process of severe plastic deformation is studied. The density of grain boundaries, dislocations and entropy are introduced for describing the defect structures appearing. This allows us to take into account the two channels of energy dissipation (thermal one and defects formation. The phase diagram that establishes the domains of realization of different limiting structures types is obtained. The interaction of several defect types on the formation of limiting structure in terms of internal energy is studied. The formation conditions for two limiting structures are found. They correspond to the mode, in which there is a mixture of different grain sizes. The kinetics of setting in the steady-state values of the defects density is investigated within the scope of the adiabatic approximation, at which the dislocations density change follows the evolution of the grain boundaries density. The external periodic influence is also analyzed. It is shown that frequency and amplitude of external influence change the system behavior.

  7. An alternating periodic-chaotic ISI sequence of HH neuron under external sinusoidal stimulus

    Institute of Scientific and Technical Information of China (English)

    Jin Wu-Yin; Xu Jian-Xue; Wu Ying; Hong Ling

    2004-01-01

    A study of Hodgkin-Huxley (HH) neuron under external sinusoidal excited stimulus is presented in this paper. As is well known, the stimulus frequency is to be considered as a bifurcate parameter, and numerous phenomena, such as synchronization, period, and chaos appear alternatively with the changing of the stimulus frequency. For the stimulus frequency less than 2fB (fB being the base frequency in this paper), the simulation results demonstrate that the single HH neuron could completely convey the sinusoidal signal in anti-phase into interspike interval (ISI) sequences. We also report, perhaps for the first time, another kind of phenomenon, the beat phenomenon, which exists in the phase dynamics of the ISI sequences of the HH neuron stimulated by a sinusoidal current. It is shown furthermore that intermittent transition results in the general route to chaos.

  8. Efficiency of transport in periodic potentials: dichotomous noise contra deterministic force

    Science.gov (United States)

    Spiechowicz, J.; Łuczka, J.; Machura, L.

    2016-05-01

    We study the transport of an inertial Brownian particle moving in a symmetric and periodic one-dimensional potential, and subjected to both a symmetric, unbiased external harmonic force as well as biased dichotomic noise η (t) also known as a random telegraph signal or a two state continuous-time Markov process. In doing so, we concentrate on the previously reported regime (Spiechowicz et al 2014 Phys. Rev. E 90 032104) for which non-negative biased noise η (t) in the form of generalized white Poissonian noise can induce anomalous transport processes similar to those generated by a deterministic constant force F= but significantly more effective than F, i.e. the particle moves much faster, the velocity fluctuations are noticeably reduced and the transport efficiency is enhanced several times. Here, we confirm this result for the case of dichotomous fluctuations which, in contrast to white Poissonian noise, can assume positive as well as negative values and examine the role of thermal noise in the observed phenomenon. We focus our attention on the impact of bidirectionality of dichotomous fluctuations and reveal that the effect of nonequilibrium noise enhanced efficiency is still detectable. This result may explain transport phenomena occurring in strongly fluctuating environments of both physical and biological origin. Our predictions can be corroborated experimentally by use of a setup that consists of a resistively and capacitively shunted Josephson junction.

  9. Influence of AC external magnetic field on guidance force relaxation between HTS bulk and NdFeB guideway

    Science.gov (United States)

    Zhang, Longcai; Wang, Suyu; Wang, Jiasu; Zheng, Jun

    2007-12-01

    Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to time-varying external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. So it is required to study whether the guidance force of the bulks is influenced by the inhomogeneity. In this paper, we studied the characteristics of the guidance force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet was used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experiment results, it was found that the guidance force was decreased with the application of the AC external magnetic field, and the decay increased with the amplitude and was almost independent of the frequency.

  10. Threshold for strong thermal dephasing in periodically poled KTP in external cavity frequency doubling

    DEFF Research Database (Denmark)

    Lundeman, Jesper Holm; Jensen, Ole Bjarlin; Andersen, Peter E.;

    2009-01-01

    We present a measurement series of the efficiency of periodically poled KTP used for second-harmonic generation in an external phase-locked cavity. Due to the high absorption (0.01 cm^−1) in the PPKTP crystal at the pump wavelength a strong thermal dephasing of the periodically poled grating...... is observed for high pump powers. For four different resonator setups, it was experimentally found that a threshold parameter could be defined as the ratio between the focal intensity in the crystal and the single-pass conversion efficiency. The value of this threshold for the onset of strong thermal...... dephasing was found to be 1.41×10^10 W^2 m^-2 in our 30-mm long PPKTP sample. This threshold parameter marks the onset of thermally induced instability that leads to a degradation of the SHG conversion efficiency. Above the threshold the shape of the resonance peaks of the resonator changed from symmetrical...

  11. Is climate change an unforeseen, irresistible and external factor - A force majeure in marine environmental law?

    Science.gov (United States)

    Saul, Roxanne; Barnes, Richard; Elliott, Michael

    2016-12-15

    Several environmental laws include provisions on natural causes or force majeure, which except States from their commitments if it can be proven that the failure to meet the commitment is due to factors outside their control. The European Union Marine Strategy Framework Directive (MSFD) has a pivotal role in managing EU marine waters. This paper analyses natural causes and force majeure provisions of the MFSD and other marine legislation, and addresses their interaction with climate change and its consequences, especially the effect on the obligation of ensuring seas are in Good Environmental Status. Climate change is an exogenic unmanaged pressure in that it emanates from outside the area being managed but in which the management authority has to respond to the consequences of climate change, such as sea level rise and temperature elevation, rather than its causes. It is suggested that a defence by a Member State of force majeure may be accepted if an event was proven to be due to an externality of control, irresistible and unforeseeable. The analysis contends that countering such a legal defence would centre on the fact that climate change is a well-accepted phenomenon, is foreseen with an accepted level of confidence and probability and is due to human actions. However, as yet, this has not been legally tested.

  12. Emergence of spike correlations in periodically forced excitable systems

    Science.gov (United States)

    Reinoso, José A.; Torrent, M. C.; Masoller, Cristina

    2016-09-01

    In sensory neurons the presence of noise can facilitate the detection of weak information-carrying signals, which are encoded and transmitted via correlated sequences of spikes. Here we investigate the relative temporal order in spike sequences induced by a subthreshold periodic input in the presence of white Gaussian noise. To simulate the spikes, we use the FitzHugh-Nagumo model and to investigate the output sequence of interspike intervals (ISIs), we use the symbolic method of ordinal analysis. We find different types of relative temporal order in the form of preferred ordinal patterns that depend on both the strength of the noise and the period of the input signal. We also demonstrate a resonancelike behavior, as certain periods and noise levels enhance temporal ordering in the ISI sequence, maximizing the probability of the preferred patterns. Our findings could be relevant for understanding the mechanisms underlying temporal coding, by which single sensory neurons represent in spike sequences the information about weak periodic stimuli.

  13. Dynamical and statistical phenomena of circulation and heat transfer in periodically forced rotating turbulent Rayleigh-Benard convection

    CERN Document Server

    Sterl, Sebastian; Zhong, Jin-Qiang

    2016-01-01

    In this paper, we present results from an experimental study into turbulent Rayleigh-Benard convection forced externally by periodically modulated unidirectional rotation rates. We find that the azimuthal rotation velocity $\\dot{\\theta}$(t) and thermal amplitude $\\delta$(t) of the large-scale circulation (LSC) are modulated by the forcing, exhibiting a variety of dynamics including increasing phase delays and a resonant peak in the amplitude of $\\dot{\\theta}$(t). We also focus on the influence of modulated rotation rates on the frequency of occurrence $\\eta$ of stochastic cessation/reorientation events, and on the interplay between such events and the periodically modulated response of $\\dot{\\theta}$(t). Here we identify a mechanism by which $\\eta$ can be amplfied by the modulated response and these normally stochastic events can occur with high regularity. We provide a modeling framework that explains the observed amplitude and phase responses, and extend this approach to make predictions for the occurrence ...

  14. Convergence Rate to Stationary Solutions for Boltzmann Equation with External Force

    Institute of Scientific and Technical Information of China (English)

    Seiji UKAI; Tong YANG; Huijiang ZHAO

    2006-01-01

    For the Boltzmann equation with an external force in the form of the gradient of a potential function in space variable, the stability of its stationary solutions as local Maxwellians was studied by S. Ukai et al. (2005) through the energy method. Based on this stability analysis and some techniques on analyzing the convergence rates to stationary solutions for the compressible Navier-Stokes equations, in this paper, we study the convergence rate to the above stationary solutions for the Boltzmann equation which is a fundamental equation in statistical physics for non-equilibrium rarefied gas. By combining the dissipation from the viscosity and heat conductivity on the fluid components and the dissipation on the non-fluid component through the celebrated H-theorem, a convergence rate of the same order as the one for the compressible Navier-Stokes is obtained by constructing some energy functionals.

  15. Solutions to Master equations of quantum Brownian motion in a general environment with external force

    Energy Technology Data Exchange (ETDEWEB)

    Roura, Albert [Los Alamos National Laboratory; Fleming, C H [UNIV OF MARYLAND; Hu, B L [UNIV OF MARYLAND

    2008-01-01

    We revisit the model of a system made up of a Brownian quantum oscillator linearly coupled to an environment made up of many quantum oscillators at finite temperature. We show that the HPZ master equation for the reduced density matrix derived earlier [B.L. Hu, J.P. Paz, Y. Zhang, Phys. Rev. D 45, 2843 (1992)] has incorrectly specified coefficients for the case of nonlocal dissipation. We rederive the QBM master equation, correctly specifying all coefficients, and determine the position uncertainty to be free of excessive cutoff sensitivity. Our coefficients and solutions are reduced entirely to contour integration for analytic spectra at arbitrary temperature, coupling strength, and cut-off. As an illustration we calculate the master equation coefficients and solve the master equation for ohmic coupling (with finite cutoff) and example supra-ohmic and sub-ohmic spectral densities. We determine the effect of an external force on the quantum oscillator and also show that our representation of the master equation and solutions naturally extends to a system of multiple oscillators bilinearly coupled to themselves and the bath in arbitrary fashion. This produces a formula for investigating the standard quantum limit which is central to addressing many theoretical issues in macroscopic quantum phenomena and experimental concerns related to low temperature precision measurements. We find that in a dissipative environment, all initial states settle down to a Gaussian density matrix whose covariance is determined by the thermal reservoir and whose mean is determined by the external force. We specify the thermal covariance for the spectral densities we explore.

  16. Quantum systems subjected to periodic and quasiperiodic external fields; Sistemas quanticos sujeitos a campos externos periodicos e quaseperiodicos

    Energy Technology Data Exchange (ETDEWEB)

    Hey, Heyder

    1996-12-31

    We have study three quantum systems under time dependent external fields. The first one is an harmonic oscillator and the external field is quasiperiodic. We prove that the autocorrelation spectrum is absolutely transient continuous covering the real line on the resonant case or pure point under supplementary diophantine conditions. The second one refers to the spin tunneling. We show that an external periodic field may causes a blocking of spin tunneling. The last problem concerns to the resonances of the Floquet spectrum on the non-perturbative region of parameters for the model of an atom with one bound state under an external periodic field. The problems of Quantum Chaology and Quantum Stability are the predominant points of view in this work. (author) 59 refs., 15 figs., 6 tabs.

  17. Effects of a compression garment on shoulder external rotation force outputs during isotonic contractions.

    Science.gov (United States)

    Tsuruike, Masaaki; Ellenbecker, Todd S

    2013-02-01

    The use of compression garments (CGs) has been advocated for performance enhancement and recovery in athletes. The effect of a CG on humeral rotation motor control has not been previously tested. The purpose of this study was to examine the isotonic contraction of external rotation (ER) of the glenohumeral joint at different force outputs to determine the effect of wearing a long sleeve CG on muscular performance. Twelve male college tennis players and 12 male college soccer players were tested for ER of the dominant shoulder during both concentric and eccentric isotonic contractions. The subjects performed 5 consecutive repetitions of both concentric and eccentric ER at 20-30% and 40-50% of maximum voluntary isometric contraction (MVIC) intensities. All subjects were tested with and without CG as well as with and without ongoing visual feedback information (OVFI). The order of CG wearing and the presence of OVFI were randomly assigned across all subjects. The results indicated a significant 3-way interaction between CG wearing and OVFI across 2 loads. Specifically, significantly different mean value of the completion time was found between OVFI and no-OVFI without CG wearing at 40-50% of MVIC, whereas no difference in the completion time was found with and without OVFI with CG wearing. Taken together, with CG wearing, athletes may have ER at 40-50% of MVIC more readily maintained by peripheral feedback without visuomotor control imposed on force outputs as compared without CG wearing.

  18. Nonexistence of ultra-subharmonic periodic orbits in periodically forced differential equation

    Institute of Scientific and Technical Information of China (English)

    Gao Jing-Wu; Li Qing-Shi

    2005-01-01

    It is proved that if there exists a periodic solution for a class of non-autonomous differential dynamic systems, it can only be subharmonic, ultra-subharmonic periodic solution is impossible. Moreover, the existence of R-type ultrasubharmonic periodic solution defined for a specified planar system is also denied. As an application of the above conclusions, through investigating some typical examples, it is pointed out that the existence of ultra-subharmonic periodic orbits in a planar perturbation system cannot be determined by second-order Melnikov method. An explanation is also provided.

  19. Stochastic Resonance in an Asymmetric Mono-stable System Subject to Two Periodic Forces and Multiplicative and Additive Noise

    Institute of Scientific and Technical Information of China (English)

    LUO Xiang-Dong; GUO Feng; ZHOU Yu-Rong

    2009-01-01

    The phenomenon of stochastic resonance (SR) in an asymmetric mono-stable system subject to two external periodic forces and multiplicative and additive noise is investigated.It is shown that the signal-to-noise ratio (SNR) for the fundamental and higher harmonics is a non-monotonic function of the intensities of the multiplicative and additive noise, as well as of the system parameter.Moreover, the SNR for the fundamental harmonic decreases with the increase of the system asymmetry, while the SNR for the higher harmonics behaves non-monotonically as the system asymmetry varies.

  20. Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012

    DEFF Research Database (Denmark)

    Muresan, Ioana Stefania; Khan, Shfaqat Abbas; Aschwanden, Andy

    thickness or retreat of the floating tongue of a glacier) caused by enhanced calving or a longer-term thinning due to a mass deficit of the ice sheet. Recent findings indicate the reduced buttressing at the marine terminus is responsible for the recent dynamic changes observed in Greenland......-term trends of several decade time scales. Here, we study the mechanisms controlling dynamic changes at the terminus of Jakobshavn Isbræ over a period of 172 years. The recent glacier acceleration began in late 1990s but there is evidence for glacier retreat of comparable magnitude in 1930s, when a similarly...... warm period occurred. To control the acceleration and retreat based on observed front positions during 1840-2012, we use an ocean model modifier that implements forcing at the ocean boundary using melange back pressure offsets. The mean temperature anomaly in west Greenland, the North Atlantic...

  1. Role of external magnetic field and current closure in the force balance mechanism of a magnetically stabilized plasma torch

    Science.gov (United States)

    G, Ravi; Goyal, Vidhi

    2012-10-01

    Experimental investigations on the role of applied external magnetic field and return current closure in the force balance mechanism of a plasma torch are reported. The plasma torch is of low power and has wall, gas and magnetic stabilization mechanisms incorporated in it. Gas flow is divided into two parts: axial-central and peripheral-shroud, applied magnetic field is axial and return current is co-axial. Results indicate that application of large external magnetic field gives rise to not only J x B force but also, coupled with gas flow, to a new drag-cum-centrifugal force that acts on the plasma arc root and column. The magnetic field also plays a role in the return current closure dynamics and thus in the overall force balance mechanism. This in turn affects the electro-thermal efficiency of the plasma torch. Detailed experimental results, analytical calculations and physical model representing the processes will be presented and discussed.

  2. A statistical modelling study of the abrupt millennial-scale climate changes focusing on the influence of external forcings

    CERN Document Server

    Mitsui, Takahito

    2015-01-01

    Dansgaard-Oeschger (DO) events are abrupt millennial-scale climate changes mainly detected in the North Atlantic region during the last glacial cycle. The frequency of the DO events varied in time, supposedly because of changes in background climate conditions. Here, we investigate the influences of external forcings on DO events with statistical modelling. We assume two types of generic stochastic dynamical systems models (double-well potential-type and oscillator-type), forced by the northern hemisphere summer insolation change and/or the global ice volume change. The models are calibrated by maximizing their likelihood and compared using the Bayesian Information Criterion (BIC). Among the models, the stochastic oscillator model forced by both insolation and ice volume changes is favored by the NGRIP calcium ion data. The BIC scores provide positive evidence for the ice volume forcing in the presence of the insolation forcing but weak evidence for the insolation forcing in the presence of the ice volume for...

  3. INVESTIGATION OF THE DYNAMIC BUCKLING OF DOUBLEWALLED CARBON NANOTUBE SUBJECTED TO AXIAL PERIODIC DISTURBING FORCES

    Institute of Scientific and Technical Information of China (English)

    SHA Feng-huan; ZHAO Long-mao; YANG Gui-tong

    2005-01-01

    The dynamic response of a double-walled carbon nanotube embedded in elastic medium subjected to periodic disturbing forces is investigated. Investigation of the dynamic buckling of a double-walled carbon nanotube develops continuum model. The effect of the van der Waals forces between two tubes and the surrounding elastic medium for axial dynamic buckling are considered. The buckling model subjected to periodic disturbing forces and the critical axial strain and the critical frequencies are given. It is found that the critical axial strain of the embedded multi-walled carbon nanotube due to the intertube van der Waals forces is lower than that of an embedded single-walled carbon nanotube. The van der Waals forces and the surrounding elastic medium affect region of dynamic instability. The van der Waals forces increase the critical frequencies of a double-walled carbon nanotube. The effect of the surrounding elastic medium for the critical frequencies is small.

  4. Heterogeneous Memorized Continuous Time Random Walks in an External Force Fields

    Science.gov (United States)

    Wang, Jun; Zhou, Ji; Lv, Long-Jin; Qiu, Wei-Yuan; Ren, Fu-Yao

    2014-09-01

    In this paper, we study the anomalous diffusion of a particle in an external force field whose motion is governed by nonrenewal continuous time random walks with correlated memorized waiting times, which involves Reimann-Liouville fractional derivative or Reimann-Liouville fractional integral. We show that the mean squared displacement of the test particle which is dependent on its location of the form (El-Wakil and Zahran, Chaos Solitons Fractals, 12, 1929-1935, 2001) where is the anomalous exponent, the diffusion exponent is dependent on the model parameters. We obtain the Fokker-Planck-type dynamic equations, and their stationary solutions are of the Boltzmann-Gibbs form. These processes obey a generalized Einstein-Stokes-Smoluchowski relation and the second Einstein relation. We observe that the asymptotic behavior of waiting times and subordinations are of stretched Gaussian distributions. We also discuss the time averaged in the case of an harmonic potential, and show that the process exhibits aging and ergodicity breaking.

  5. Existence and uniqueness of periodic solutions for forced Liénard-type equations

    Institute of Scientific and Technical Information of China (English)

    LIU Bing-wen

    2008-01-01

    By using topological degree theory and some analysis skill, some sufficient conditions for the existence and uniqueness of periodic solutions for a class of forced Liénard-type equations are obtained.

  6. Stability analysis for periodic solutions of the Van der Pol-Duffing forced oscillator

    Science.gov (United States)

    Cui, Jifeng; Liang, Jiaming; Lin, Zhiliang

    2016-01-01

    Based on the homotopy analysis method (HAM), the high accuracy frequency response curve and the stable/unstable periodic solutions of the Van der Pol-Duffing forced oscillator with the variation of the forced frequency are obtained and studied. The stability of the periodic solutions obtained is analyzed by use of Floquet theory. Furthermore, the results are validated in the light of spectral analysis and bifurcation theory.

  7. Period Prevalence of Acute Neck Injury in US Air Force Pilots Exposed to High G Forces

    Science.gov (United States)

    1986-06-01

    unquantified clinical and epidemiological problem in exposed pilots. There has been a paucity of research in this area. This proposal is a beginning, with a...larg-e majority of pilots. Thus neck injury and its sequelae are unquantified clinical and epidemiological problems in pilots exposed to high G forces...Basal Impression 19. Cervical Ribs 20. Scoliosis , 21. Intraspongy Nuclear Hernitation 22. Significant Compression or Loss of Height of Any Vertebral

  8. Orbital motion in generalized static fields of FELs accounting for axial magnetic field, beam forces, undulator and external focusing

    Energy Technology Data Exchange (ETDEWEB)

    Papadichev, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)

    1995-12-31

    Various types of undulators with or without axial magnetic field are used in FELs. Supplementary beam focusing can be applied by wedging, inclining or profiling pole faces of plan undulators or superposing external focusing magnetic fields in addition to undulator own focusing. Space-charge forces influence significantly particle motion in high-current, low-energy electron beams. Finally, one can use simultaneously two or more different undulators for some specific purpose: more efficient and selective higher harmonics generation, changing polarization types and direction, gain enhancement in double-period undulator etc. All these cases can be treated by solving the generalized equations of transverse orbital motion in a linear approximation, which is widely used for orbit calculation, gives sufficient accuracy for practical purposes and allows to consider many variants and optimize the chosen one. The undulator field is described as a field of two plane undulators with mutually orthogonal fields and an arbitrary axial (phase) shift between them. Various values of the phase shift correspond to right- or left-handed helical undulators, plane undulator of different polarization etc. The general formulae are reduced to forms that allow easier examination of particular cases: planar or helical undulator combined with axial magnetic field or without it, gyroresonance, limiting beam current, polarization etc.

  9. Calculation of force distribution for a periodically supported beam subjected to moving loads

    Science.gov (United States)

    Hoang, T.; Duhamel, D.; Foret, G.; Yin, H. P.; Joyez, P.; Caby, R.

    2017-02-01

    In this study, a novel model for a periodically supported beam subjected to moving loads was developed using a periodicity condition on reaction forces. This condition, together with Fourier transforms and Dirac combs, forms a relation between the beam displacement and support reaction forces. This relation explains the force distribution at the supports, and holds for any type of support and foundation behaviors. Based on this relation, a system equivalence for a periodically supported beam is presented in this paper. An application to non-ballasted viscoelastic supports is presented as an example and the results clearly match the existing model. Next, an approximation of real-time responses was developed for the moving loads as periodic series. The comparison shows that this approximation can be used for a limited number of loads if the distances between loads are sufficiently large. The system equivalence for a periodically supported beam is efficient for supports with linear behavior, and could be extended to other behaviors.

  10. Critical Behavior of the Gaussian Model with Periodic Interactions on Diamond-Type Hierarchical Lattices in External Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    LIN ZhenQuan; KONG XiangMu; JIN JinShuang; YANG ZhanRu

    2001-01-01

    The Gaussian spin model with periodic interactions on the diamond-type hierarchical lattices is constructed by generalizing that with uniform interactions on translationally invariant lattices according to a class of substitution sequences. The Gaussian distribution constants and imposed external magnetic fields are also periodic depending on the periodic characteristic of the interaction bonds. The critical behaviors of this generalized Gaussian model in external magnetic fields are studied by the exact renormalization-group approach and spin rescaling method. The critical points and all the critical exponents are obtained. The critical behaviors are found to be determined by the Gaussian distribution constants and the fractal dimensions of the lattices. When all the Gaussian distribution constants are the same, the dependence of the critical exponents on the dimensions of the lattices is the same as that of the Gaussian model with uniform interactions on translationally invariant lattices.

  11. Low External Electric Field Periodic Poling of Thick LiTaO3

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A promising method of ferroelectric domain inverted structures was demonstrated, which allows us to fabricate thicker domain inverted patterns by applying a lower external electric field in LiTaO3 crystal. The external field for the domain reversal of the 1.5 mm thick LiTaO3 at 500 ℃ was only 6 V·mm-1, which is lower by three orders of magnitude than that in LiTaO3 crystal at room temperature. The process of the domain inversion structure was also studied. The fabrication techniques are based on controlled temperature and field duration time.

  12. Biopolymers under large external forces and mean-field RNA virus evolutionary dynamics

    Science.gov (United States)

    Ahsan, Syed Amir

    The modeling of the mechanical response of single-molecules of DNA and RNA under large external forces through statistical mechanical methods is central to this thesis with a small portion devoted to modeling the evolutionary dynamics of positive-sense single-stranded RNA viruses. In order to develop and test models of biopolymer mechanics and illuminate the mechanisms underlying biological processes where biopolymers undergo changes in energy on the order of the thermal energy, , entails measuring forces and lengths on the scale of piconewtons (pN) and nanometers (nm), respectively. A capacity achieved in the past two decades at the single-molecule level through the development of micromanipulation techniques such as magnetic and optical tweezers, atomic force microscopy, coupled with advances in micro- and nanofabrication. The statistical mechanical models of biopolymers developed in this dissertation are dependent upon and the outcome of these advancements and resulting experiments. The dissertation begins in chapter 1 with an introduction to the structure and thermodynamics of DNA and RNA, highlighting the importance and effectiveness of simple, two-state models in their description as a prelude to the emergence of two-state models in the research manuscripts. In chapter 2 the standard models of the elasticity of polymers and of a polymer gel are reviewed, characterizing the continuum and mean-field models, including the scaling behavior of DNA in confined spaces. The research manuscript presented in the last section of chapter 2 (section 2.5), subsequent to a review of a Flory gel and in contrast to it, is a model of the elasticity of RNA as a gel, with viral RNA illustrating an instance of such a network, and shown to exhibit anomalous elastic behavior, a negative Poisson ratio, and capable of facilitating viral RNA encapsidation with further context provided in section 5.1. In chapter 3 the experimental methods and behavior of DNA and RNA under mechanical

  13. Quasi-periodic Henon-like attractors in the Lorenz-84 climate model with seasonal forcing

    NARCIS (Netherlands)

    Broer, HW; Vitolo, R; Simo, C; Dumortier, F; Broer, H; Mawhin, J; Vanderbauwhede, A; Lunel, SV

    2005-01-01

    A class of strange attractors is described, occurring in a low-dimensional model of general atmospheric circulation. The differential equations of the system are subject to periodic forcing, where the period is one year - as suggested by Lorenz in 1984. The dynamics of the system is described in ter

  14. Self-consistent treatment of electrostatics in molecular DNA braiding through external forces.

    Science.gov (United States)

    Lee, Dominic J

    2014-06-01

    In this paper we consider a physical system in which two DNA molecules braid about each other. The distance between the two molecular ends, on either side of the braid, is held at a distance much larger than supercoiling radius of the braid. The system is subjected to an external pulling force, and a moment that induces the braiding. In a model, developed for understanding such a system, we assume that each molecule can be divided into a braided and unbraided section. We also suppose that the DNA is nicked so that there is no constraint of the individual linking numbers of the molecules. Included in the model are steric and electrostatic interactions, thermal fluctuations of the braided and unbraided sections of the molecule, as well as the constraint on the braid linking (catenation) number. We compare two approximations used in estimating the free energy of the braided section. One is where the amplitude of undulations of one molecule with respect to the other is determined only by steric interactions. The other is a self-consistent determination of the mean-squared amplitude of these undulations. In this second approximation electrostatics should play an important role in determining this quantity, as suggested by physical arguments. We see that if the electrostatic interaction is sufficiently large there are indeed notable differences between the two approximations. We go on to test the self-consistent approximation-included in the full model-against experimental data for such a system, and we find good agreement. However, there seems to be a slight left-right-handed braid asymmetry in some of the experimental results. We discuss what might be the origin of this small asymmetry.

  15. Characteristics of the internal and external sources of the Mediterranean synoptic cyclones for the period 1956-2013

    Science.gov (United States)

    Almazroui, Mansour; Awad, Adel M.; Nazrul Islam, M.

    2017-07-01

    This paper investigates the main sources and features of the Mediterranean synoptic cyclones affecting the basin, using the cyclone tracks. The cyclones' tracks are identified using sea level pressure (SLP) from the NCEP/NCAR reanalysis data for the period 1956-2013. The identified cyclones are classified into two categories: basin affected and basin non-affected. Most of the basin-affected (non-affected) cyclones are internal (external), i.e., generated inside (outside) the Mediterranean basin. This study reveals four (five) main sources of internal (external) cyclones. These four (five) main sources generated about 63.76% (57.25%) of the internal (external) cyclones. Seasonal analysis shows that most of the basin-affected internal (external) cyclones were generated in the winter (spring) season. The lowest number of cyclones were found in the summer. Moreover, the synoptic study of the atmospheric systems accompanied the highest- and lowest-generated years demonstrates that the deepening of the north Europe cyclones and the relative positions of Azores- and Siberian-high systems represent the important factors that influence the number of internal cyclones. Essential factors influencing the external cyclones are the strength of the maximum upper wind, Azores high, Siberian high, and orientations of their ridges.

  16. Effect of nonsinusoidal periodic forces in Duffing oscillator: Numerical and analog simulation studies

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, K. [Department of Physics, National Institute of Technology, Tiruchirapalli 620 015 (India); Thamilmaran, K. [Centre for Nonlinear Dynamics, Department of Physics, Bharathidasan University, Tiruchirapalli 620 024 (India)], E-mail: maran@cnld.bdu.ac.in; Venkatesan, A. [Department of Physics, Nehru Memorial College, Puthanampatti - P.O., Tiruchirappalli 621 007 (India)

    2009-04-15

    We consider the effect of different nonsinusoidal periodic forces like square wave, triangle wave, sawtooth wave on Duffing oscillator and show that the system can undergo distinctly modified bifurcation structure, generation of new periodic regimes, reverse period-doubling bifurcations, intermittency, antimonotonicity, induction of crises. The dynamics was studied numerically using one parameter bifurcation diagrams, phase portraits and Lyapunov exponents. Most of these numerical studies are in good agreement with observations from analog circuit simulation experiments.

  17. Influence of an inner core on the long-period forced librations of Mercury

    Science.gov (United States)

    Yseboodt, Marie; Rivoldini, Attilio; Van Hoolst, Tim; Dumberry, Mathieu

    2013-09-01

    The planetary perturbations on Mercury’s orbit lead to long-period forced librations of Mercury’s mantle. These librations have previously been studied for a planet with two layers: a mantle and a liquid core. Here, we calculate how the presence of a solid inner core in the liquid outer core influences the long-period forced librations. Mantle-inner core coupling affects the long-period libration dynamics mainly by changing the free libration: first, it lengthens the period of the free libration of the mantle, and second, it adds a second free libration, closely related to the free gravitational oscillation between the mantle and inner core. The two free librations have periods between 2.5 and 18y depending on the internal structure. We show that large amplitude long-period librations of a few tens of arcsec are generated when the period of a planetary forcing approaches one of the two free libration periods. These amplitudes are sufficiently large to be detectable by spacecraft measurements of the libration of Mercury. The amplitudes of the angular velocity of Mercury’s mantle at planetary forcing periods are also amplified by the resonances, but remain much smaller than the current precision of Earth-based radar observations unless the period is very close to a free libration period. The inclusion of mantle-inner core coupling in the rotation model does not significantly improve the fit to the radar observations. This implies that it is not yet possible to determine the size of the inner core of Mercury on the basis of available observations of Mercury’s rotation rate. Future observations of the long-period librations may be used to constrain the interior structure of Mercury, including the size of its inner core.

  18. Influence of external climate forcing on coastal upwelling systems analysed in ensemble of past millennium climate simulations

    Science.gov (United States)

    Tim, Nele; Zorita, Eduardo; Hünicke, Birgit; Yi, Xin; Emeis, Kay

    2016-04-01

    Eastern Boundary Upwelling Systems are highly productive coastal ocean areas where nutrient rich, cold water upwells by the action of favorable winds. Observations over the 20th century and ocean sediment records, which may be indicative of upwelling, display an intensification due to stronger external climate forcing, such as increasing greenhouse gas concentrations or changes in solar irradiance. This intensification is compatible with the hypothesis put forward by Bakun (1990) that a stronger external radiative forcing should lead to a more intense coastal upwelling. Here, we analyze ensemble of simulations covering the past millennium with the aim of identifying and quantifying the role of external climate forcing on upwelling in the major Eastern Boundary Upwelling System. We analyse the decadal variability and centennial trends of upwelling in ensemble of simulations with the global climate model MPI-ESM covering the past millennium, the last 150 years and the next 100 years. The future simulations were driven by three IPCC scenarios of concentrations of anthropogenic greenhouse gases, RCP2.5, RCP4.5 and RCP 8.5. For the past millennium and the last 150 years, coastal upwelling does not show any imprint of external forcing. This result indicates that chaotic internal variability has dominated upwelling intensity in major upwelling regions over the last thousand years and even since industrialisation up to present. For the 21st century, all ensemble members show a consistent and significant intensification of upwelling in the strongest scenario RCP8.5 for the Benguela upwelling region, consistent and significant weakening for Morocco and California, and no significant change for the Peruvian upwelling. Weaker scenarios do not produce consistent long-term trends that are replicated in all ensemble members. The results are confirmed by analysing another ensemble of past millennium simulations with the model CESM-CAM5 (Community Earth System Model

  19. Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012

    Science.gov (United States)

    Muresan, I. S.; Khan, S. A.; Aschwanden, A.; Khroulev, C.; Bjork, A. A.; Box, J. E.

    2014-12-01

    Greenland's main outlet glaciers have more than doubled their contribution to global sea-level rise over the past decade through acceleration of ice discharge. One of the triggering mechanisms is a reduction in resistance (buttressing) at the marine based glacier front (i.e. through reduced thickness or retreat of the floating tongue of a glacier) caused by enhanced calving or a longer-term thinning due to a mass deficit of the ice sheet. Recent findings indicate the reduced buttressing at the marine terminus is responsible for the recent dynamic changes observed in Greenland, but the controlling processes and triggering mechanisms are still unclear. Furthermore, our current understanding is almost entirely based on observations from a short-term record spanning only from a year to a decade, and is characterized by short-term fluctuations and therefore not representative for longer-term trends of several decade time scales. Here, we study the mechanisms controlling dynamic changes at the terminus of Jakobshavn Isbræ over a period of 172 years. The recent glacier acceleration began in late 1990s but there is evidence for glacier retreat of comparable magnitude in 1930s, when a similarly warm period occurred. To control the acceleration and retreat based on observed front positions during 1840-2012, we use an ocean model modifier that implements forcing at the ocean boundary using melange back pressure offsets. The mean temperature anomaly in west Greenland, the North Atlantic oscillation (NAO) winter index and the Atlantic multidecadal oscillation (AMO) index anomalies for the period 1900-2012 sustain our modelling results. The modelled surface elevation changes near the front are considered and compared with observed surface elevation changes for the period 1880-2012. Furthermore, the modelled mass loss signal between 1997-2012 is validated based on ice mass change observations which we estimate using altimeter surveys from NASA's ATM flights during 1997

  20. Significance of Neglected Hydrodynamic Forces on the Motion of Submerged Particles Acted on by External Body Forces

    Science.gov (United States)

    Cooper, Daniel; Charonko, John; Vlachos, Pavlos

    2011-11-01

    Recently, the manipulation of submerged particles using electromagnetic body forces has drawn increasing interest from a variety of fields, particularly medicine, where electrophoretic manipulation in lab-on-a-chip applications and magnetic drug targeting have become important areas of interest. As a direct result of this increasing interest a large number of simulations have been performed investigating the performance of devices and systems whose operation is based upon these physics. In the vast majority of cases, these simulations are based upon a force balance of the applicable body force and Stokes drag. Such simulations neglect additional hydrodynamic forces, including the added mass, Basset, Saffman, and Magnus forces. In the current study, the full equations of motion containing all of the aforementioned terms are nondimensionalized leading to a set of nondimensional parameters governing the behavior of the particle. A parametric investigation is then performed by calculating particle trajectories for both Poiseuille and Womersley flows. This analysis reveals that in many cases, the forces neglected in previous simulations are significant and should not be neglected in future studies.

  1. Ordered and isomorphic mapping of periodic structures in the parametrically forced logistic map

    Science.gov (United States)

    Maranhão, Dariel M.

    2016-09-01

    We investigate the periodic domains found in the parametrically forced logistic map, the classical logistic map when its control parameter changes dynamically. Phase diagrams in two-parameter spaces reveal intricate periodic structures composed of patterns of intersecting superstable orbits curves, defining the cell of a periodic window. Cells appear multifoliated and ordered, and they are isomorphically mapped when one changes the map parameters. Also, we identify the characteristics of simplest cell and apply them to other more complex, discussing how the topography on parameter space is affected. By use of the winding number as defined in periodically forced oscillators, we show that the hierarchical organization of the periodic domains is manifested in global and local scales.

  2. Autoclaved aerated concrete masonry with external insulation. Features of moisture conditions during the initial period of operation (rus

    Directory of Open Access Journals (Sweden)

    Kuptaraeva P.D.

    2011-12-01

    Full Text Available Building designs at the moment of commissioning include the initial (building and technological moisture. Thermal insulation systems influence on the yield of the initial moisture from the structures. However, there are no specific design requirements about determining initial moisture content in insulation systems.In this article the features of the initial period of operation on an example of aerated concrete are defined: the results of field surveys and calculations are shown and compared. On the basis of this comparison basic advice on the accounting features of the initial period of operation of autoclaved aerated concrete structures with external insulation are given.

  3. Sensitivity of oxygen dynamics in the water column of the Baltic Sea to external forcing

    Directory of Open Access Journals (Sweden)

    S. Miladinova

    2010-04-01

    Full Text Available A 1-D biogeochemical/physical model of marine systems has been applied to study the oxygen cycle in four stations of different sub-basins of the Baltic Sea, namely, in the Gotland Deep, Bornholm, Arkona and Fladen. The model consists of the biogeochemical model of Neumann et al. (2002 coupled with the 1-D General Ocean Turbulence Model (GOTM. The model has been forced with meteorological data from the ECMWF reanalysis project for the period 1998–2003, producing a six year hindcast which is validated with datasets from the Baltic Environmental Database (BED for the same period. The vertical profiles of temperature and salinity are relaxed towards both profiles provided by 3-D simulations of General Estuarine Transport Model (GETM and observed profiles from BED. Modifications in the parameterisation of the air-sea oxygen fluxes have led to a significant improvement of the model results in the surface and intermediate water layers. The largest mismatch with observations is found in simulating the oxygen dynamics in the Baltic Sea bottom waters. The model results demonstrate the good capability of the model to predict the time-evolution of the physical and biogeochemical variables at all different stations. Comparative analysis of the modelled oxygen concentrations with respect to observation data is performed to distinguish the relative importance of several factors on the seasonal, interannual and long-term variations of oxygen. It is found that natural physical factors, like the magnitude of the vertical turbulent mixing, wind speed and the variation of temperature and salinity fields are the major factors controlling the oxygen dynamics in the Baltic Sea. The influence of limiting nutrients is less pronounced, at least under the nutrient flux parameterisation assumed in the model.

  4. Influence of an inner core on the long-period forced librations of Mercury

    CERN Document Server

    Yseboodt, Marie; Van Hoolst, Tim; Dumberry, Mathieu

    2013-01-01

    The planetary perturbations on Mercury's orbit lead to long-period forced librations of Mercury's mantle. These librations have previously been studied for a planet with two layers: a mantle and a liquid core. Here, we calculate how the presence of a solid inner core in the liquid outer core influences the long-period forced librations. Mantle-inner core coupling affects the long-period libration dynamics mainly by changing the free libration: first, it lengthens the period of the free libration of the mantle, and second, it adds a second free libration, closely related to the free gravitational oscillation between the mantle and inner core. The two free librations have periods between 2.5 and 18 y depending on the internal structure. We show that large amplitude long-period librations of 10's of arcsec are generated when the period of a planetary forcing approaches one of the two free libration periods. These amplitudes are sufficiently large to be detectable by spacecraft measurements of the libration of Me...

  5. Effects of the availability of an external area on dairy cows welfare during summer period

    Directory of Open Access Journals (Sweden)

    L. Stefanini

    2011-03-01

    Full Text Available Problems of environmental pollution, as well as the need to ensure the cleanliness of the milking cows, do not suggest the use of external paddock. On the contrary, for the production of organic milk, the access to the paddock or pasture is compulsory, as the presence of the paddock could improve animal welfare, particularly in hot summer conditions. The negative effects of heat stress are not simply restricted to a lower milk yield but also lead to a worsening of milk composition (Bernabucci and Calamari, 1998 and cheesemaking properties (Calamari and Mariani, 1998.....

  6. Statistical Mechanics of DNA unzipping under periodic force: Scaling behavior of hysteresis loop

    CERN Document Server

    Kumar, Sanjay

    2013-01-01

    A simple model of DNA based on two interacting polymers has been used to study the unzipping of a double stranded DNA subjected to a periodic force. We propose a dynamical transition, where without changing the physiological condition, it is possible to bring DNA from the zipped/unzipped state to a new dynamic (hysteretic) state by varying the frequency of the applied force. Our studies reveal that the area of the hystersis loop grows with the same exponents as of the isotropic spin systems. These exponents are amenable to verification in the force spectroscopic experiments.

  7. Different types of scaling in the dynamics of period–doubling maps under external periodic driving

    Directory of Open Access Journals (Sweden)

    N. Yu. Ivank’ov

    2000-01-01

    Full Text Available Based on the renormalization group approach developed by Kuznetsov and Pikovsky (Phys. Lett., A140, 1989, 166 several types of scaling are discussed, which can be observed in a neighborhood of Feigenbaum’s critical point at small amplitudes of the driving. The type of scaling behavior depends on a structure of binary representation of the frequency parameter: F-scaling (Feigenbaum’s for finite binary fractions, P- and Q-scaling (periodic and quasiperiodic for periodic binary fractions, and S-scaling (statistical for non-periodic binary fractions. All types of scaling are illustrated by parameter-plane diagrams for the rescaled Lyapunov exponent.

  8. A Study of Stochastic Resonance in the Periodically Forced Rikitake Dynamo

    Directory of Open Access Journals (Sweden)

    Chien-Chih Chen Chih-Yuan Tseng

    2007-01-01

    Full Text Available The geodynamo has widely been thought to be an intuitive and selfsustained model of the Earth¡¦s magnetic field. In this paper, we elucidate how a periodic signal could be embedded in the geomagnetic filed via the mechanism of stochastic resonance in a forced Rikitake dynamo. Based on the stochastic resonance observed in the periodically forced Rikitake dynamo, we thus suggest a common triggering for geomagnetic reversal and glacial events. Both kinds of catastrophes may result from the cyclic variation of the Earth¡¦s orbital eccentricity.

  9. Theoretical study of enhancing the piezoelectric nanogenerator's output power by optimizing the external force's shape

    Science.gov (United States)

    Xu, Qi; Qin, Yong

    2017-07-01

    The average power is one of the key parameters of piezoelectric nanogenerators (PENGs). In this paper, we demonstrate that the PENG's output can be gigantically improved by choosing driving force with an appropriate shape. When the load resistance is 100 MΩ and the driven forces have a magnitude of 19.6 nN, frequency of 10 Hz, the average power of PENG driven by square shaped force is six orders of magnitude higher than that driven by triangular shaped and sinusoidal shaped forces. These results are of importance for optimizing the average power of the PENGs in practical applications.

  10. Periodic Solutions of the Forced Pendulum: Exchange of Stability and Bifurcations

    Science.gov (United States)

    Katriel, Guy

    2002-06-01

    We study the T-periodic solutions of the forced pendulum equation u″+cu‧+a sin(u)=λf(t), where f satisfies f(t+{T}/{2})=-f(t). We prove that this equation always has at least two geometrically distinct T-periodic solutions u0 and u1. We then investigate the dependence of the set of T-periodic solutions on the forcing strength λ. We prove that under some restriction on the parameters a,c, the periodic solutions found before can be smoothly parameterized by λ, and that there are some λ-intervals for which u0(λ), u1(λ) are the only T-periodic solutions up to geometrical equivalence, but there are other λ-intervals in which additional T-periodic solutions bifurcate off the branches u0(λ), u1(λ). We characterize the global structure of the bifurcating branches. Related to this bifurcation phenomenon is the phenomenon of 'exchange of stability' - in some λ-intervals u0(λ) is dynamically stable and u1(λ) is unstable, while in other λ-intervals the reverse is true, a phenomenon which has important consequences for the dynamics of the forced pendulum, as we show by both theoretical analysis and numerical simulation.

  11. Dynamical ordering of non-Birkhoff periodic orbits in a forced pendulum

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Yoshihiro [Teikyo Heisei Univ., Ichihara, Chiba (Japan); Tanikawa, Kiyotaka [National Astronomical Observatory, Mitaka, Tokyo (Japan)

    2001-12-01

    Forced pendulums induce reversible non-monotone twist mappings. Non-Birkhoff periodic orbits (NBO) are found in these mappings, and hence in the pendulums. The existence of an NBO is equivalent to the non-integrability of the system. Two types of dynamical ordering for NBOs are obtained. (author)

  12. Dynamical Ordering of Non-Birkhoff Periodic Orbits in a Forced Pendulum

    Science.gov (United States)

    Yamaguchi, Y.; Tanikawa, K.

    2001-12-01

    Forced pendulums induce reversible non-monotone twist mappings. Non-Birkhoff periodic orbits (NBO) are found in these mappings, and hence in the pendulums. The existence of an NBO is equivalent to the non-integrability of the system. Two types of dynamical ordering for NBOs are obtained.

  13. A Periodic Solution of the Generalized Forced Liénard Equation

    Directory of Open Access Journals (Sweden)

    Zahra Goodarzi

    2014-01-01

    Full Text Available We consider the generalized forced Liénard equation as follows: (ϕp(x′′+(f(x+k(xx′x′+g(x=p(t+s. By applying Schauder's fixed point theorem, the existence of at least one periodic solution of this equation is proved.

  14. Dynamics and Complexity in a Time Delay Model of RNA Silencing with Periodic Forcing

    Directory of Open Access Journals (Sweden)

    Svetoslav Nikolov

    2008-10-01

    Full Text Available Simple periodic behavior and occurrence of complex oscillatory phenomena underlie of a large number of biochemical system models. In many cases the transition from stable to simple/complex oscillatory behavior can be connected with the appearance of abnormal process likes as cancer. In this paper we propose a time delay model of RNA silencing (also known as RNA interference with periodic forcing. In organisms with RNA silencing, each cell has a miniature "immune system" able to generate and amplify specific responses to a variety of gene transcripts. The consequences of a time delay on the dynamics of this model are analysed using Hopf's theorem. Our analytical calculations predict that time delay acts as a key bifurcation parameter. From the accomplished numerical results, it becomes clear that model has complexity oscillatory behavior when the amplitude of periodic force (i.e. the confusion in the target mRNA synthesis is large.

  15. The role of external forcing and Pacific trade winds in recent changes of the global climate system

    Science.gov (United States)

    Friedman, Andrew; Gastineau, Guillaume; Khodri, Myriam

    2017-04-01

    The Pacific trade winds experienced an unprecedented strengthening since the mid 1990s. Several studies have proposed that the increased Pacific trade winds were associated with the reduced rate of global mean surface temperature warming in the first decade of the 21st century, as well as far-reaching atmospheric teleconnections. We designed a set of ensemble partial coupling experiments using the IPSL-CM5A-LR coupled model that allow us to cleanly distinguish the influence of Pacific trade wind variability from that of external forcing over the past few decades. In this study, we quantify the respective impacts of these processes on surface temperature, ocean heat content, and atmospheric teleconnections. We designed two ensembles of coupled simulations using partial coupling with the IPSL-CM5A-LR model to separate the Pacific internal variability and that of external radiative forcing. We prescribe surface wind stress in the tropical Pacific (20°S to 20°N) from 1979-2014 in two ensembles of 30 members each: (1) Prescribed climatological model wind stress, which allows us to estimate the influence of external radiative forcing in the absence of variability within the Pacific Ocean. (2) Wind stress anomalies from ERA-Interim reanalysis added to the model wind stress climatology, which accounts for the effects of both external radiative forcing and the wind stress variability. We find that the observed wind stress anomalies account for the pattern of eastern tropical Pacific cooling when compared to the climatology experiment, so that it resembles the observed trends from 1992-2011. The tropical Pacific shows dominant heat uptake in the western Pacific above the 20°C isotherm, which contributed to slow the warming of tropical SST during the 2000s. The trade wind increase is associated with a strengthening of the Pacific Walker circulation, and zonal shifts in tropical rainfall. Despite tropical SST biases which affect the response of tropical rainfall and the

  16. Taking Advantage of External Funding for Air Force Officer PH.D. Candidates at Civilian Universities

    Science.gov (United States)

    2009-12-01

    Education,” http://www.afit.edu/grad.cfm. 21 Clarence W. Hannon et al., “Graduate Education within the Armed Forces,” Group Research Project...Force Line Officers, Research Report no. AFHRL-TR-70-7 (Lackland AFB, TX: Personnel Research Division, 1970). 56 Clarence W. Hannon et al...Bolton, Benjamin F. Findley, William S. Mosley, Lawrence Mwambola, Jeffrey N. Renehan, Glenward L. Spivey, John F. Thompson , Jack Weinstein. ―Air

  17. Decoupled external forces in a predictor-corrector segmentation scheme for LV contours in Tagged MR images.

    Science.gov (United States)

    Garcia-Barnes, Jaume; Andaluz, Albert; Carreras, Francesc; Gil, Debora

    2010-01-01

    Computation of functional regional scores requires proper identification of LV contours. On one hand, manual segmentation is robust, but it is time consuming and requires high expertise. On the other hand, the tag pattern in TMR sequences is a problem for automatic segmentation of LV boundaries. We propose a segmentation method based on a predictor-corrector (Active Contours - Shape Models) scheme. Special stress is put in the definition of the AC external forces. First, we introduce a semantic description of the LV that discriminates myocardial tissue by using texture and motion descriptors. Second, in order to ensure convergence regardless of the initial contour, the external energy is decoupled according to the orientation of the edges in the image potential. We have validated the model in terms of error in segmented contours and accuracy of regional clinical scores.

  18. Melnikov analysis and chaos control of nonlinear dispersive KdV equation under external periodic perturbation

    Science.gov (United States)

    Yin, J. L.; Xing, Q. Q.; Tian, L. X.

    2015-03-01

    The behavior of non-smooth solitary waves switching to chaos is studied. Firstly, we present some singular homoclinic orbits of an unperturbed system. These singular homoclinic orbits correspond to non-smooth solutions. Secondly, we find that the peculiar solitary waves are more likely to be chaos by using the Melnikov theory. Finally, chaos thresholds under different amplitudes and frequencies of a periodic perturbation are given. One interesting finding is that there exists a peculiar perturbation frequency, which has significant effect on the system. The system is not well-controlled under this frequency. However, the system can be well controlled, when the frequency of the perturbation surpasses the peculiar perturbation frequency with fixed parameters of the unperturbed system.

  19. The list of external reports published by Reactor Centrum Nederland with subject and author index. Period 1960-1976

    Energy Technology Data Exchange (ETDEWEB)

    Schaaf, B. van der

    2005-08-10

    The Reactor Centrum Nederland, RCN, published 249 external reports in the period from 1960 to 1976, when the series terminated. In the latter year RCN changed course from a mainly nuclear oriented research and development organization into the Energieonderzoek Centrum Nederland, ECN, covering energy in general. This series of 249 reports, of which 3 cannot be retrieved, is only a fraction of the publications RCN generated. The annual reports over that 16 years period include lists of many more publications in the open domain. In addition the organization produced a wealth of reports for customers, partners, beneficiaries and internal use. The latter category of reports had mostly a restricted or confidential character, and consequently has only been circulated internally. The external RCN report series served several purposes. The analyses and experimental methods often required more detailed descriptions than usually possible in papers in journals and for symposia. Software frequently needed more detailed description than space allowed in the open publication domain. Several databases, compiled on the bases of experimental and analytical efforts, had to be opened for the public domain. Studies covering large projects such as the design and building of ship propulsion and development of fusion power plant concepts are also part of the series goals. These reports provide the space to present the meaningful detail of such largescale undertakings. The progress reporting of international projects such as the fast breeder development community and international materials development projects used the external RCN reports to reach the partners in the co-operations. The series served these purposes well. The reports were quoted frequently in restricted and in open literature as well to underpin the conclusions drawn in the limited paper space of the other media for the communication of science and technology developments

  20. The list of external reports published by Energieonderzoek Centrum Nederland with subject and author index. Period 1976-1989

    Energy Technology Data Exchange (ETDEWEB)

    Schaaf, B. van der

    2005-08-15

    The Energieonderzoek Centrum Nederland, ECN, published 225 external reports in the period from 1976 to 1989 covering energy in general. This series of 225, of which 3 reports cannot be retrieved, is only a fraction of the publications ECN generated. The annual reports over that period of 13 years include lists of many more publications in the open domain. In addition the organisation produced a wealth of reports for customers, partners, beneficiaries and internal use. The latter category of reports had a most restricted or confidential character and consequently has only been circulated internally. The external ECN report series served several purposes. On many occasions the analyses and experimental methods needed more detailed descriptions than usually possible in papers, in journals and for symposia contributions. Software required more detailed description than space allowed in the open publication domain. Several databases generated with experimental (qualification of steel for fast reactor construction) and analytical efforts (determination of cross sections for design libraries) had to be opened for the public domain. Studies, such as the development of fusion power plant concepts are also part of the purpose. These reports provide the space to present the meaningful detail of such large-scale undertakings. Several theses prepared under ECN sponsorship have been published in the series as well. The series served the purposes well. They were quoted frequently in restricted and in open literature as well to underpin the conclusions drawn in the limited paper space of the other media for the communication of science and technology developments

  1. Forcing a unitary transformation by an external field comparing two approaches based on optimal control theory

    CERN Document Server

    Palao, J P; Palao, Jose P.; Kosloff, Ronnie

    2002-01-01

    A quantum gate is realized by specific unitary transformations operating on states representing qubits. Considering a quantum system employed as an element in a quantum computing scheme, the task is therefore to enforce the pre-specified unitary transformation. This task is carried out by an external time dependent field. Optimal control theory has been suggested as a method to compute the external field which alters the evolution of the system such that it performs the desire unitary transformation. This study compares two recent implementations of optimal control theory to find the field that induces a quantum gate. The first approach is based on the equation of motion of the unitary transformation. The second approach generalizes the state to state formulation of optimal control theory. This work highlight the formal relation between the two approaches.

  2. THE DEPENDENCE OF HEAT CONSUMPTION ON THE DYNAMICS OF EXTERNAL AIR TEMPERATURE DURING COLD SNAP PERIODS

    Directory of Open Access Journals (Sweden)

    Rymarov Andrey Georgievich

    2014-09-01

    Full Text Available The dynamics of outdoor temperature variations during the cold period of the year influences the operation of the systems providing the required microclimate in the premises, which may be subject to automation systems that affects the IQ of a building, it is important to note that in the last decade there has been a growth in the participation of intelligent technologies in the formation of a microclimate of buildings. Studying the microclimate quality in terms of energy consumption of the premises and the building considers climate variability and outdoor air pollution, which is connected with the economic aspects of energy efficiency and productivity, and health of workers, as a short-term temperature fall in the premises has harmful consequences. Low outdoor temperatures dry the air in the premises that requires accounting for climate control equipment and, if necessary, the personal account of its work. Excess heat in the premises, including office equipment, corrects the temperature conditions, which reduces the adverse effect of cold snap.

  3. Synchronization and bifurcation structures in coupled periodically forced non-identical Duffing oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, U E [Department of Physics, Olabisi Onabanjo University, PMB 2002, Ago-Iwoye (Nigeria); Kenfack, A [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany)], E-mail: kenfack@pks.mpg.de

    2008-04-15

    We study the bifurcation structure and the synchronization of a double-well Duffing oscillator coupled to a single-well one and subjected to periodic forces. Using the amplitudes and the frequencies of these driving forces as control parameters, we show that our model presents phenomena which were not observed in a similar system but with identical potentials. In the regime of relatively weak coupling, bubbles of bifurcations and chains of symmetry-breaking are identified. For much stronger couplings, Hopf bifurcations born from orbits of higher periodicity, as well as subcritical and supercritical Neimark bifurcations emerge. Varying the coupling strength, we also find a threshold for which the system remains quasiperiodic. Moreover, tori-breakdown route to a strange non-chaotic attractor is another highlight of features found in this model. In two parameter diagrams, regions of chaos and quasiperiodicity are clearly identified. Finally, threshold parameters for which synchronization occurs have been found.

  4. Forces and Phases: An Investigation of Azimuthal Plasma and Field Periodicities in Saturn's Inner Magnetosphere

    Science.gov (United States)

    Ramer, K. M.; Kivelson, M. G.; Khurana, K. K.; Sergis, N.; Walker, R. J.; Jia, X.

    2012-12-01

    In Saturn's magnetosphere, periodic fluctuations are ubiquitous; for example, periodicities have been observed in Saturn Kilometric Radiation (SKR), in auroral emissions, in magnetic perturbations, in electron density, and in energetic particle fluxes. In this study, we extend the search for periodicities at Saturn by examining additional plasma and magnetic field parameters in Saturn's inner magnetosphere near the equatorial plane. Our study uses data acquired by the Cassini spacecraft during the equatorial passes from Oct 11, 2005 to May 24, 2006. We have found that the intermittency of in situ measurements in the inner magnetosphere precludes the use of the frequency sweeping technique adopted by Gurnett et al. [2007] to establish the optimum rotation period. We, therefore, use rotation periods already in use: first the slowly changing SLS3 period based on SKR measurements, and second the period based on the magnetic field [Provan et al., 2011], to establish phases and obtain evidence that magnetic pressure, plasma pressure, density, and angular velocity are periodically modulated. We then establish the phase relationships among these parameters to test azimuthal force balance and we compare these results to simulations by Jia et al. [2012].

  5. Logarithmic interaction under periodic boundary conditions: closed form formulas for energy and forces

    Science.gov (United States)

    Tyagi, Sandeep

    A method is given to obtain closed form formulas for the energy and forces for an aggregate of charges interacting via a logarithmic interaction under periodic boundary conditions. The work done here is a generalization of Glasser's results [J. Math. Phys., 15, 188 (1974)] and is obtained with a different and simpler method than that by Stremler [J. Math. Phys., 45, 3584 (2004)]. The simplicity of the formulas derived here makes them extremely convenient in a computer simulation.

  6. Logarithmic interaction under periodic boundary conditions: Closed form formulas for energy and forces

    OpenAIRE

    2005-01-01

    A method is given to obtain closed form formulas for the energy and forces for an aggregate of charges interacting via a logarithmic interaction under periodic boundary conditions. The work done here is a generalization of Glasser's results [M. L. Glasser, J. Math. Phys. 15, 188 (1974)] and is obtained with a different and simpler method than that by Stremler [M. A. Stremler, J. Math. Phys. 45, 3584 (2004)]. The simplicity of the formulas derived here makes them extremely convenient in a comp...

  7. Euler-Poincaré Reduction of Externally Forced Rigid Body Motion

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    2004-01-01

    . Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincaré reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modelling, estimation and control of mechanical systems......-known Euler-Poincaré reduction to a rigid body motion with forcing....

  8. What causes periodic beating in sperm flagella: synchronized internal forcing or fluid-structure interaction?

    Science.gov (United States)

    Prabhakar, Ranganathan; Nandagiri, Ashwin; Jadhav, Sameer

    2016-11-01

    Eucaryotic cells such as sperm propel themselves using internally driven flagella. Two different models for the origin of the whip-like beating observed in such flagella are compared. The first model assumes that internal protein motors actuate synchronously to cause a traveling active-force wave within the filament. The forcing wave is chosen such that its resultant and the total torque on the filament are zero. In contrast, the second model assumes that forces and torques exerted by the motors locally sum to zero across the scale of the filament diameter. The only effect of the motor activity is to give rise to a stresslet distribution across the filament length. In either model, the slender filament is modeled as a bead-spring chain with hydrodynamic interactions. Flagellar waveforms and trajectory patterns obtained are compared systematically while keeping the dissipation rates the same for the two models. Periodic beating emerges in freely swimming filaments with the second model without any imposed periodicity in the stresslet distribution. This suggests that periodic waveforms in eucaryotic flagella can emerge by fluid-structure interactions alone without significant internal synchronization of protein motor activity.

  9. Electrostatic and aerodynamic forced vibrations of a thin flexible electrode: Quasi-periodic vs. chaotic oscillations.

    Science.gov (United States)

    Madanu, Sushma B; Barbel, Stanley I; Ward, Thomas

    2016-06-01

    In this paper, transverse vibrations of an electrostatically actuated thin flexible cantilever perturbed by low-speed air flow are studied using both experiments and numerical modeling. In the experiments, the dynamic characteristics of the cantilever are studied by supplying a DC voltage with an AC component for electrostatic forcing and a constant uniform air flow around the cantilever system for aerodynamic forcing. A range of control parameters leading to stable vibrations are established using a dimensionless operating parameter that is the ratio of the induced and the free stream velocities. Numerical results are validated with experimental data. Assuming the amplitude of vibrations are small, then a non-linear dynamic Euler-Bernoulli beam equation with viscous damping and gravitational effects is used to model the equation of motion. Aerodynamic forcing is modelled as a temporally sinusoidal and uniform force acting perpendicular to the beam length. The forcing amplitude is found to be proportional to the square of the air flow velocity. Numerical results strongly agree with the experiments predicting accurate vibration amplitude, displacement frequency, and quasi-periodic displacement of the cantilever tip.

  10. Late Pliocene to Pleistocene sensitivity of the Greenland Ice Sheet in response to external forcing and internal feedbacks

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Sebastian J.; DeConto, Robert M. [University of Massachusetts, Department of Geosciences, Amherst, MA (United States); Pollard, David [Pennsylvania State University, Earth and Environmental Systems Institute, College of Earth and Mineral Sciences, University Park, PA (United States)

    2011-09-15

    The timing and nature of ice sheet variations on Greenland over the last {proportional_to}5 million years remain largely uncertain. Here, we use a coupled climate-vegetation-ice sheet model to determine the climatic sensitivity of Greenland to combined sets of external forcings and internal feedbacks operating on glacial-interglacial timescales. In particular, we assess the role of atmospheric pCO{sub 2}, orbital forcing, and vegetation dynamics in modifying thresholds for the onset of glaciation in late Pliocene and Pleistocene. The response of circum-Arctic vegetation to declining levels of pCO{sub 2} (from 400 to 200 ppmv) and decreasing summer insolation includes a shift from boreal forest to tundra biomes, with implications for the surface energy balance. The expansion of tundra amplifies summer surface cooling and heat loss from the ground, leading to an expanded summer snow cover over Greenland. Atmospheric and land surface fields respond to forcing most prominently in late spring-summer and are more sensitive at lower Pleistocene-like levels of pCO{sub 2}. We find cold boreal summer orbits produce favorable conditions for ice sheet growth, however simulated ice sheet extents are highly dependent on both background pCO{sub 2} levels and land-surface characteristics. As a result, late Pliocene ice sheet configurations on Greenland differ considerably from late Pleistocene, with smaller ice caps on high elevations of southern and eastern Greenland, even when orbital forcing is favorable for ice sheet growth. (orig.)

  11. Predicting the conditions under which vibroacoustic resonances with external periodic loads occur in the primary coolant circuits of VVER-based NPPs

    Science.gov (United States)

    Proskuryakov, K. N.; Fedorov, A. I.; Zaporozhets, M. V.

    2015-08-01

    The accident at the Japanese Fukushima Daiichi nuclear power plant (NPP) caused by an earthquake showed the need of taking further efforts aimed at improving the design and engineering solutions for ensuring seismic resistance of NPPs with due regard to mutual influence of the dynamic processes occurring in the NPP building structures and process systems. Resonance interaction between the vibrations of NPP equipment and coolant pressure pulsations leads to an abnormal growth of dynamic stresses in structural materials, accelerated exhaustion of equipment service life, and increased number of sudden equipment failures. The article presents the results from a combined calculation-theoretical and experimental substantiation of mutual amplification of two kinds of external periodic loads caused by rotation of the reactor coolant pump (RCP) rotor and an earthquake. The data of vibration measurements at an NPP are presented, which confirm the predicted multiple amplification of vibrations in the steam generator and RCP at a certain combination of coolant thermal-hydraulic parameters. It is shown that the vibration frequencies of the main equipment may fall in the frequency band corresponding to the maximal values in the envelope response spectra constructed on the basis of floor accelerograms. The article presents the results from prediction of conditions under which vibroacoustic resonances with external periodic loads take place, which confirm the occurrence of additional earthquake-induced multiple growth of pressure pulsation intensity in the steam generator at the 8.3 Hz frequency and additional multiple growth of vibrations of the RCP and the steam generator cold header at the 16.6 Hz frequency. It is shown that at the elastic wave frequency equal to 8.3 Hz in the coolant, resonance occurs with the frequency of forced vibrations caused by the rotation of the RCP rotor. A conclusion is drawn about the possibility of exceeding the design level of equipment vibrations

  12. Quasi-two-layer finite-volume scheme for modeling shallow water flows with the presence of external forces

    CERN Document Server

    Karelsky, K V; Slavin, A G

    2011-01-01

    The numerical method for study of hydrodynamic flows over an arbitrary bed profile in the presence of external force is proposed in this paper. This method takes into account the external force effect, it uses the quasi-two-layer model of hydrodynamic flows over a stepwise boundary with consideration of features of the flow near the step. A distinctive feature of the proposed method is the consideration of the properties of the process of the waterfall, namely the fluid flow on the step in which the fluid does not wet part of the vertical wall of the step. The presence of dry zones in the vertical part of the step indicates violation of the conditions of hydrostatic flow. The quasi-two-layer approach allows to determine the size of the dry zone of the vertical component of the step. Consequently it gives an opportunity to figure out the amount of kinetic energy dissipation. There are performed the numerical simulations based on the proposed algorithm of various physical phenomena, such as a breakdown of the r...

  13. Improvements in springback control by external force laser-assisted sheet bending of titanium and aluminum alloys

    Science.gov (United States)

    Gisario, A.; Barletta, M.; Venettacci, S.

    2016-12-01

    The present investigation deals with an external-force laser assisted bending process of Grade 2 CP titanium and AA 7075 T6 aluminum sheets. High bending angles, sharp fillet radii and control of springback were achieved by tuning the contact pressure of a hydraulically driven tool with the local and selective heating of the bending zone by irradiation with a high power diode laser. First, the role of laser operational parameters, namely power, scanning speed and number of passes, in metal bending was investigated, allowing to identify the most suitable processing window. Second, a custom-built equipment to measure the bending angle during the forming process, together with the metal temperature, was implemented. Real-time monitoring of the bending angle and temperature allowed to evaluate the continuous evolution of the geometry of the metal substrates during the external force laser-assisted bending process. Experimental results showed both metal sheets could be bent to high angles with very low fillet radii by the appropriate combination of the tooling contact pressure and selective laser heating of the bending zone. Laser heating also reduces the risk of rupture in both metals during bending at high angles, limits the springback extent up to 10 times on titanium and 30 times on aluminum in comparison with conventional bending process and does not affect significantly the visual appearance of the bending zone.

  14. Pipeline integrity management: integration of geotechnical and mechanical assessment to control potential risks due to external forces

    Energy Technology Data Exchange (ETDEWEB)

    Malpartida Moya, John E.; Sota, Giancarlo Massucco de la; Seri, Walter [Compania Operadora de Gas del Amazonas, Lima (Peru)

    2009-07-01

    Every pipeline integrity management system evaluates and controls various threats. On pipelines which have particular characteristics as it is the case of the Andean pipelines and pipelines crossing jungles, one of the main threats are the external forces. Even, this threat causes a greater number of failures than other threats like corrosion or the third part damage. Facing this situation, the pipeline integrity management system of TgP has achieved an important development in the use and suitable handling of the information provided by diverse techniques of pipeline mechanical inspection and geotechnical inspection of the right-of-way (ROW). This document presents our methodology, which interrelate information of the in-line inspection, information of geotechnical inspections of the ROW, instrumentation (Strain Gages), topographic monitoring, among others. All this information is supported in a Geographic Information System (GIS) which allows us to integrate the information. By means of the pipeline integrity management system we control potential risks due to external forces, we have been able to act before events become critical, with no occurrence of failures. This system allows us simultaneously to optimize efforts and preserve the mechanical integrity of our pipelines, not producing neither personal nor environmental nor economical affectation. (author)

  15. An Examination of the External and Internal Forces that have Shaped the Department of Veterans Affairs

    Science.gov (United States)

    2014-05-22

    vacation to the West coast.65 However, before his death, and in another of his interesting management choices , he selected a highly qualified...of the bonus.98 Congress was more forgiving and recognized the public perception of the Army’s use of force on veterans. They voted to provide a per...Hoover to head the review. Mr. Hoover, a Republican, may have seemed an unusual choice for a Democratic President, but he was a respected organizer

  16. Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing

    Directory of Open Access Journals (Sweden)

    E. Katragkou

    2009-05-01

    Full Text Available Regional air quality decadal simulations were carried out using the air quality model CAMx driven off-line by the regional climate model RegCM3 for the time slice 1991–2000 using two different datasets of external meteorological forcing to constrain RegCM3: the ERA40 global atmospheric reanalysis dataset and the output from the GCM ECHAM5. The focus of this work is to compare the perfect lateral boundary conditions experiment with the GCM driven control experiment and to investigate how this external meteorological forcing affects near surface ozone. The different RegCM3 meteorological forcings resulted in changes of near surface ozone over Europe ranging between ±5 ppb for winter and summer, while all model parameterizations and anthropogenic emissions remained unchanged. Changes in near surface ozone are induced by changes in meteorological fields and biogenic emissions, which are on-line calculated and meteorology-dependent. The model simulations suggest that the change in solar radiation is the factor that mostly modulates the ozone changes in summer. During winter season it is found that the induced changes in NOx explain about 40% of the ozone variability. The meteorological induced changes in biogenic emissions are quite low for winter with rather small impact on ozone while they are more temperature than radiation dependent. Using multiple regression analysis to associate the changes in near surface ozone with the respective changes in selected meteorological parameters and ozone precursors, an explained variance of 70% in summer and 60% in winter is reproduced.

  17. Bumetanide prevents transient decreases in muscle force in murine hypokalemic periodic paralysis.

    Science.gov (United States)

    Wu, Fenfen; Mi, Wentao; Cannon, Stephen C

    2013-03-19

    To test the hypothesis that inhibition of the Na-K-2Cl transporter with bumetanide will reduce the susceptibility to decreases in muscle force in a mouse model of hypokalemic periodic paralysis (HypoPP). In vitro contraction tests were performed on soleus muscle isolated from mice with knock-in missense mutations that result in HypoPP (sodium channel NaV1.4-R669H) or hyperkalemic periodic paralysis (HyperPP; sodium channel NaV1.4-M1592V). Bumetanide prevented the development of weakness in 2 mM K(+) and also restored force during an established attack of HypoPP. Stimulation of the Na-K-2Cl transporter via induction of hyperosmolality exacerbated the weakness seen in low K(+) and was also prevented by bumetanide. Bumetanide was more efficacious than acetazolamide for preventing weakness in low K(+) conditions. Decreases in force in HyperPP muscle exposed to 10 mM K(+) were not prevented by treatment with bumetanide. The Na-K-2Cl inhibitor bumetanide was highly effective in preventing attacks of weakness in the NaV1.4-R669H mouse model of HypoPP and should be considered for management of patients with HypoPP due to sodium channel mutations. Dehydration may aggravate HypoPP by stimulating the Na-K-2Cl transporter.

  18. Bifurcations from stationary to periodic solutions in a low-order model of forced, dissipative barotropic flow

    Science.gov (United States)

    Mitchell, K. E.; Dutton, J. A.

    1981-01-01

    The considered investigation is concerned with periodic solutions in the context of a forced, dissipative, barotropic spectral model truncated to three complex coefficients with constant forcing on only the intermediate scale. It is found that determining a periodic solution of this three-coefficient model also reduces to finding the algebraic roots of a real polynomial. In the derivation of this polynomial, a class of hydrodynamic spectral systems is described for which a periodic solution might be similarly specified. The existence of periodic solutions of the three-coefficient model is controlled by the roots of the stability polynomial of the basic stationary solution, which represents the simplest response to the constant forcing. When the forcing exceeds a critical value, the basic solution becomes unstable. Owing to the nature of the roots of the stability polynomial at critical forcing, bifurcation theory guarantees the existence of a periodic solution.

  19. Experimental evidence of landscape reorganization under changing external forcing: implications to climate-driven knickpoints

    Science.gov (United States)

    Singh, Arvind; Tejedor, Alejandro; Grimaud, Jean-Louis; Foufoula-Georgiou, Efi

    2017-04-01

    Understanding and quantifying geomorphic and topologic re-organization of landscape in response to changing climatic or tectonic forcing is of scientific and practical interest. Although several studies have addressed the large-scale response (e.g., change in mean relief), studies on the smaller-scale drainage pattern re-organization and quantification of landscape vulnerability to the timing, magnitude, and frequency of changing forcing are lacking. To that goal, a series of controlled laboratory experiments were conducted to study the effect of changing precipitation patterns on landscape evolution at the short and long-time scales. High resolution digital elevation (DEM) both in space and time were measured for a range of rainfall patterns and uplift rates. Results from our study show a distinct signature of the precipitation increase on the probabilistic and geometrical structure of landscape features, evident in widening and deepening of channels and valleys, change in drainage patterns within sub-basins and change in the space-time structure of erosional and depositional events. A spatially explicit analysis of the locus of these erosional and depositional events show an acceleration of erosion in the hillslopes when the rainfall intensity is increased, while the incision in fluvial channels is slowed down exhibiting a sediment-flux dependent behavior. Finally, we document the changes in the longitudinal river profiles with increasing precipitation intensity, revealing the formation of knickpoints at certain confluences where large discontinuities in the ratio Qs/Qw are observed.

  20. External forcing of earthquake swarms at Alpine regions: example from a seismic meteorological network at Mt. Hochstaufen SE-Bavaria

    Directory of Open Access Journals (Sweden)

    V. Svejdar

    2011-11-01

    Full Text Available In the last few years, it has been shown that above-average rainfall and the following diffusion of excess water into subsurface structures is able to trigger earthquake swarms in the uppermost brittle portion of the Earth's crust. However, there is still an ongoing debate on whether the crust already needs to be in a critical-to-failure state or whether it is sufficient that water is transported rapidly within channels and veins of karst or similar geological formations to the underlying, earthquake-generating layers. Also unknown is the role of other forcing mechanisms, possible co-variables and probably necessary tectonic loading in the triggering process of earthquakes. Because of these problems, we do not use an explicit physical model but instead analyze the meteorological and geophysical data via sophisticated statistical models. ewline We are interested in the influence of a more complete set of possible forcing parameters, including the influence of synthetic earth tides, on the occurrence of earthquake swarms. In this context, regression models are the adequate tool, since the calculation of simple correlations can be confounded by the other variables. Since our outcome variable (the number of quakes is a count, we use Poisson regression models that include the plausible assumption of a Poisson distribution for the counts. For this study, we use nearly continuous recordings of a seismic and meteorological network in the years 2002–2008 at Mt. Hochstaufen in SE-Bavaria. Our non-linear regression model reveals correlations between external forces and the triggering of earthquakes. In addition to the still dominant influence of rainfall, theoretical estimated tidal tilt show some weak influence on the swarm generation. However, the influence of the modeled trend functions shows that rain is by far not the most important forcing mechanism present in the data.

  1. Effect of external shearing force on exfoliation structure and properties of high-performance epoxy/clay nanocomposites

    Institute of Scientific and Technical Information of China (English)

    LU Hai-jun; ZHANG Bao-yan; CHEN Xiang-bao

    2005-01-01

    To further investigate the influence of organic modifiers (primary amine with catalytic hydrogen and quaternary alkylammonium salt) on exfoliation behavior of clay tactoids, high-speed emulsifying and homogeneous mixing(HEHM) and ball milling were used to exert external shearing force on two organic clay tactoids (termed as MMTDDA and MMTDBDA, respectively), which were organically modified with DoDecyl Amine(DDA) and Dodecyl Benzyl Dimethyl Ammonium chloride(DBDA) ,respectively. The effects of external shearing force on microstructure and properties of both resultant nanocomposites were investigated by X-ray diffractometry(XRD), transmission electron microscopy(TEM) and thermogravimetric analysis(TGA). The results show that whether the clay tactoids are organically modified with catalytic primary amine or quaternary alkylammonium salt, the large agglomerates will not be finely dispersed or exfoliated by conventional mixing (magnetic stirring). After being vigorously sheared by HEHM or ball milling, the dispersion and exfoliation of clay tactoids are increasingly promoted for both MMTDDA and MMTDBDA, and the mechanical properties of the high-performance epoxy/clay nanocomposites are enhanced. For epoxy/MMTDDA nanocomposites, impact strength can be increased up to 44.5 kJ/m2 from 32.1 kJ/m2 , which is about 39% higher than that of pristine matrix, and the flexural strength is enhanced by about 4%. A similar enhancement for epoxy/MMTDBDA nanocomposites has also been achieved. Improvement on thermal stability of epoxy/clay nanocomposites is dependent on the exfoliation of clay layers and molecular structure of the modifiers. The onset temperature is increased with the clay loading decreasing from 5% or higher content to 3% (mass fraction), and the DBDA modifier with the heat-resistant benzyl may also improve the stability of epoxy/MMTDBDA nanocomposites.

  2. The importance of ENSO nonlinearities in tropical pacific response to external forcing

    Science.gov (United States)

    Karamperidou, Christina; Jin, Fei-Fei; Conroy, Jessica L.

    2016-12-01

    Tropical Pacific climate varies at interannual, decadal and centennial time scales, and exerts a significant influence on global climate. Climate model projections exhibit a large spread in the magnitude and pattern of tropical Pacific warming in response to greenhouse-gas forcing. Here, we show that part of this spread can be explained by model biases in the simulation of interannual variability, namely the El Niño/Southern Oscillation (ENSO) phenomenon. We show that models that exhibit strong ENSO nonlinearities simulate a more accurate balance of ENSO feedbacks, and their projected tropical Pacific sea surface temperature warming pattern is closely linked to their projected ENSO response. Within this group, models with ENSO nonlinearity close to observed project stronger warming of the cold tongue, whereas models with stronger than observed ENSO nonlinearity project a more uniform warming of the tropical Pacific. These differences are also manifest in the projected changes of precipitation patterns, thereby highlighting that ENSO simulation biases may lead to potentially biased projections in long-term precipitation trends, with great significance for regional climate adaptation strategies.

  3. Theoretical analysis of ferromagnetic microparticles in streaming liquid under the influence of external magnetic forces

    Science.gov (United States)

    Brandl, Martin; Mayer, Michael; Hartmann, Jens; Posnicek, Thomas; Fabian, Christian; Falkenhagen, Dieter

    2010-09-01

    The microsphere based detoxification system (MDS) is designed for high specific toxin removal in extracorporeal blood purification using functionalized microparticles. A thin wall hollow fiber membrane filter separates the microparticle-plasma suspension from the bloodstream. For patient safety, it is necessary to have a safety system to detect membrane ruptures that could lead to the release of microparticles into the bloodstream. A non-invasive optical detection system including a magnetic trap is developed to monitor the extracorporeal venous bloodstream for the presence of released microparticles. For detection, fluorescence-labeled ferromagnetic beads are suspended together with adsorbent particles in the MDS circuit. In case of a membrane rupture, the labeled particles would be released into the venous bloodstream and partly captured by the magnetic trap of the detector. A physical model based on fluidic, gravitational and magnetic forces was developed to simulate the motion and sedimentation of ferromagnetic particles in a magnetic trap. In detailed simulation runs, the concentrations of accumulated particles under different applied magnetic fields within the magnetic trap are shown. The simulation results are qualitatively compared with laboratory experiments and show excellent accordance. Additionally, the sensitivity of the particle detection system is proofed in a MDS laboratory experiment by simulation of a membrane rupture.

  4. Theoretical analysis of ferromagnetic microparticles in streaming liquid under the influence of external magnetic forces

    Energy Technology Data Exchange (ETDEWEB)

    Brandl, Martin, E-mail: martin.brandl@donau-uni.ac.a [Center for Biomedical Technology, Danube University Krems, Krems (Austria); Mayer, Michael [University of Applied Sciences, St. Poelten (Austria); Hartmann, Jens; Posnicek, Thomas [Center for Biomedical Technology, Danube University Krems, Krems (Austria); Fabian, Christian [University of Applied Sciences, St. Poelten (Austria); Falkenhagen, Dieter [Center for Biomedical Technology, Danube University Krems, Krems (Austria)

    2010-09-15

    The microsphere based detoxification system (MDS) is designed for high specific toxin removal in extracorporeal blood purification using functionalized microparticles. A thin wall hollow fiber membrane filter separates the microparticle-plasma suspension from the bloodstream. For patient safety, it is necessary to have a safety system to detect membrane ruptures that could lead to the release of microparticles into the bloodstream. A non-invasive optical detection system including a magnetic trap is developed to monitor the extracorporeal venous bloodstream for the presence of released microparticles. For detection, fluorescence-labeled ferromagnetic beads are suspended together with adsorbent particles in the MDS circuit. In case of a membrane rupture, the labeled particles would be released into the venous bloodstream and partly captured by the magnetic trap of the detector. A physical model based on fluidic, gravitational and magnetic forces was developed to simulate the motion and sedimentation of ferromagnetic particles in a magnetic trap. In detailed simulation runs, the concentrations of accumulated particles under different applied magnetic fields within the magnetic trap are shown. The simulation results are qualitatively compared with laboratory experiments and show excellent accordance. Additionally, the sensitivity of the particle detection system is proofed in a MDS laboratory experiment by simulation of a membrane rupture.

  5. Unzipping DNA by a periodic force: hysteresis loop area and its scaling.

    Science.gov (United States)

    Kapri, Rajeev

    2014-12-01

    Using Monte Carlo simulations, we study the hysteresis in the unzipping of double-stranded DNA whose ends are subjected to a time-dependent periodic force with frequency (ω) and amplitude (G). For the static force, i.e., ω→0, the DNA is in equilibrium with no hysteresis. On increasing ω, the area of the hysteresis loop initially increases and becomes maximum at frequency ω*(G), which depends on the force amplitude G. If the frequency is increased further, we find that for lower amplitudes the loop area decreases monotonically to zero, but for higher amplitudes it has an oscillatory component. The height of subsequent peaks decreases, and finally the loop area becomes zero at very high frequencies. The number of peaks depends on the length of the DNA. We give a simple analysis to estimate the frequencies at which maxima and minima occur in the loop area. We find that the area of the hysteresis loop scales as 1/ω in the high-frequency regime, whereas it scales as G(α)ω(β) with exponents α=1 and β=5/4 at low frequencies. The values of the exponents α and β are different from the exponents reported earlier based on the hysteresis of small hairpins.

  6. Molecular dynamics study of response of liquid N,N-dimethylformamide to externally applied electric field using a polarizable force field

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Weimin; Niu, Haitao; Lin, Tong; Wang, Xungai; Kong, Lingxue [Institute for Frontier Materials, Deakin University, Waurn Ponds VIC 3216 (Australia)

    2014-01-28

    The behavior of Liquid N,N-dimethylformamide subjected to a wide range of externally applied electric fields (from 0.001 V/nm to 1 V/nm) has been investigated through molecular dynamics simulation. To approach the objective the AMOEBA polarizable force field was extended to include the interaction of the external electric field with atomic partial charges and the contribution to the atomic polarization. The simulation results were evaluated with quantum mechanical calculations. The results from the present force field for the liquid at normal conditions were compared with the experimental and molecular dynamics results with non-polarizable and other polarizable force fields. The uniform external electric fields of higher than 0.01 V/nm have a significant effect on the structure of the liquid, which exhibits a variation in numerous properties, including molecular polarization, local cluster structure, rotation, alignment, energetics, and bulk thermodynamic and structural properties.

  7. Anti-periodic traveling wave solution to a forced two-dimensional generalized KdV-Burgers equation

    Institute of Scientific and Technical Information of China (English)

    TAN Junyu

    2003-01-01

    The anti-periodic traveling wave solutions to a forced two-dimensional generalized KdV-Burgers equation are studied.Some theorems concerning the boundness, existence and uniqueness of the solution to this equation are proved.

  8. External control of the Drosophila melanogaster egg to imago development period by specific combinations of 3D low-frequency electric and magnetic fields.

    Science.gov (United States)

    Makarov, Vladimir I; Khmelinskii, Igor

    2016-01-01

    We report that the duration of the egg-to-imago development period of the Drosophila melanogaster, and the imago longevity, are both controllable by combinations of external 3-dimensional (3D) low-frequency electric and magnetic fields (LFEMFs). Both these periods may be reduced or increased by applying an appropriate configuration of external 3D LFEMFs. We report that the longevity of D. melanogaster imagoes correlates with the duration of the egg-to-imago development period of the respective eggs. We infer that metabolic processes in both eggs and imago are either accelerated (resulting in reduced time periods) or slowed down (resulting in increased time periods). We propose that external 3D LFEMFs induce electric currents in live systems as well as mechanical vibrations on sub-cell, whole-cell and cell-group levels. These external fields induce media polarization due to ionic motion and orientation of electric dipoles that could moderate the observed effects. We found that the longevity of D. melanogaster imagoes is affected by action of 3D LFEMFs on the respective eggs in the embryonic development period (EDP). We interpret this effect as resulting from changes in the regulation mechanism of metabolic processes in D. melanogaster eggs, inherited by the resulting imagoes. We also tested separate effects of either 3D electric or 3D magnetic fields, which were significantly weaker.

  9. The generalized Langevin equation revisited: Analytical expressions for the persistence dynamics of a viscous fluid under a time dependent external force

    Science.gov (United States)

    Olivares-Rivas, Wilmer; Colmenares, Pedro J.

    2016-09-01

    The non-static generalized Langevin equation and its corresponding Fokker-Planck equation for the position of a viscous fluid particle were solved in closed form for a time dependent external force. Its solution for a constant external force was obtained analytically. The non-Markovian stochastic differential equation, associated to the dynamics of the position under a colored noise, was then applied to the description of the dynamics and persistence time of particles constrained within absorbing barriers. Comparisons with molecular dynamics were very satisfactory.

  10. Use of a device that applies external kneading-like force on the abdomen for treatment of constipation

    Institute of Scientific and Technical Information of China (English)

    Konstantinos Mimidis; David Galinsky; Efraim Rimon; Vassilios Papadopoulos; Yehuda Zicherman; Dimitrios Oreopoulos

    2005-01-01

    AIM: To evaluate the efficacy of a recently developed device that applies kneading-like motion on the abdomen in improving constipation in elderly long-term care patients.METHODS: Thirty constipated elderly patients were randomly selected from two nursing homes. They were instructed to use the device once daily for 20 min. Rate of bowel movements, volume and consistency of stool and the use of laxantia were all recorded during a 3-wk baseline period and for 12-wk treatment period. Colonic transit time (CTT) was measured in 13 patients by radiopaque markers during the baseline and at the end of treatment.RESULTS: Bowel movement rate (BM/week) increased from 1.4±0.4 BM/wk during baseline to 3.9±0.8 BM/wk during treatment (P<5.0×10-7). Stool amount that was "low" in 30 patients during baseline increased in 21 patients at the end of the study period (χ2 = 19.048-P =1.3×10-5). Stool consistency, that was "hard" in 25 patients and "soft" in 5 patients during baseline, ameliorated in 23 patients at the end of the study (only 2 patients referred "hard" stool) (χ2= 21.043-P = 4.0×10-6). The mean baseline CTT measured was 92.3±32.3 h at baseline and decreased to 49.4±31.3 h during the study period (P = 0.000208). No side effects were observed during the study period.CONCLUSION: External mechanical vibration of the abdomen reduced CTT and helped to relieve severe constipation in elderly constipated patients.

  11. Periodic even and odd-harmonic solutions of the equation of the forced pendulum

    Science.gov (United States)

    Schmitt, B. V.; Sari, N.

    The periodic solutions of the simple forced-pendulum equation analyzed by Schmitt and Mazzanti (1981), and Schmitt (1982) are investigated numerically, using computer integrations by a fourth-order Runge-Kutta method (Henrici, 1962) with a step corresponding to 25 iterations per solution to explore the initial conditions of the even and odd-harmonic solutions. The variation of these conditions with respect to the parameters omega and b is shown in a series of maps, and the reliability of the results, despite the approximate nature of numerical integration algorithms and the necessary rounding errors, is seen as demonstrated by double-precision computations and calculations of similar problems with known analytical solutions.

  12. Viscous damping and spring force in periodic perforated planar microstructures when the Reynolds’ equation cannot be applied

    Science.gov (United States)

    Homentcovschi, Dorel; Miles, Ronald N.

    2010-01-01

    A model of squeeze-film behavior is developed based on Stokes’ equations for viscous, compressible isothermal flows. The flow domain is an axisymmetrical, unit cell approximation of a planar, periodic, perforated microstructure. The model is developed for cases when the lubrication approximation cannot be applied. The complex force generated by vibrations of the diaphragm driving the flow has two components: the damping force and the spring force. While for large frequencies the spring force dominates, at low (acoustical) frequencies the damping force is the most important part. The analytical approach developed here yields an explicit formula for both forces. In addition, using a finite element software package, the damping force is also obtained numerically. A comparison is made between the analytic result, numerical solution, and some experimental data found in the literature, which validates the analytic formula and provides compelling arguments about its value in designing microelectomechanical devices. PMID:20329828

  13. Synchronization and chaos control in a periodically forced quasi-geostrophic two-layer model of baroclinic instability

    Directory of Open Access Journals (Sweden)

    F. J. R. Eccles

    2006-01-01

    Full Text Available Cyclic forcing on many timescales is believed to have a significant effect on various quasi-periodic, geophysical phenomena such as El Niño, the Quasi-Biennial Oscillation, and glacial cycles. This variability has been investigated by numerous previous workers, in models ranging from simple energy balance constructions to full general circulation models. We present a numerical study in which periodic forcing is applied to a highly idealised, two-layer, quasi-geostrophic model on a β-plane. The bifurcation structure and (unforced behaviour of this particular model has been extensively examined by Lovegrove et al. (2001 and Lovegrove et al. (2002. We identify from their work three distinct regimes on which we perform our investigations: a steady, travelling wave regime, a quasi-periodic, modulated wave regime and a chaotic regime. In the travelling wave regime a nonlinear resonance is found. In the periodic regime, Arnol'd tongues, frequency locking and a Devil's staircase is seen for small amplitudes of forcing. As the forcing is increased the Arnol'd tongues undergo a period doubling route to chaos, and for larger forcings still, the parameter space we explored is dominated by either period 1 behaviour or chaotic behaviour. In the chaotic regime we extract unstable periodic orbits (UPOs and add the periodic forcing at periods corresponding to integer multiples of the UPO periods. We find regions of synchronization, similar to Arnol'd tongue behaviour but more skewed and centred approximately on these periods. The regions where chaos suppression took place are smaller than the synchronization regions, and are contained within them.

  14. Efficacy and retention of Basic Life Support education including Automated External Defibrillator usage during a physical education period

    Directory of Open Access Journals (Sweden)

    Kae Watanabe

    2017-03-01

    Full Text Available The American Heart Association (AHA advocates for CPR education as a requirement of secondary school curriculum. Unfortunately, many states have not adopted CPR education. Our aim was to investigate a low-cost, time effective method to educate students on Basic Life Support (BLS, including reeducation. This is a prospective, randomized study. Retention was assessed at 4 months post-initial education. Education was performed by AHA-certified providers during a 45-minute physical education class in a middle school in Florida. This age provides opportunities for reinforcement through high school, with ability for efficient learning. The study included 41 Eighth grade students. Students were randomized into two groups; one group received repeat education 2 months after the first education, the second group did not. All students received BLS education limited to chest compressions and usage of an Automated External Defibrillator. Students had skills and knowledge tests administered pre- and post-education after initial education, and repeated 2 and 4 months later to assess retention. There was a significant increase in CPR skills and knowledge when comparing pre- and post-education results for all time-points (p < 0.001. When assessing reeducation, a significant improvement was noted in total knowledge scores but not during the actual steps of CPR. Our study indicates significant increase in CPR knowledge and skills following a one-time 45-minute session. Reeducation may be useful, but the interval needs further investigation. If schools across the United States invested one 45–60-minute period every school year, this would ensure widespread CPR knowledge with minimal cost and loss of school time.

  15. Periodicity in a Conceptual Model of Glacial Cycles in the Absence of Milankovitch Forcing

    Science.gov (United States)

    Hahn, J.; Walsh, J.; Widiasih, E.; McGehee, R.

    2015-12-01

    Previously, McGehee and Widiasih coupled Budyko's Energy Balance Model with dynamics of a latitudinal ice-line incorporating the albedo feedback effect. They reduced this model to a two-dimensional equation of global mean temperature and a latitudinal ice-line. With this conceptual model, we now include dynamics of the ablation and accumulation of ice, to form a three-dimensional system that partitions the regions of the Earth latitudinally into an accumulation zone, ablation zone, and ice-free zone. Motivated by the findings of Abe-Ouchi et al that the fast retreat of ice-sheets is due to an increased rate of ablation via the effects of delayed isostatic rebound, we incorporate a simple switching mechanism to the model which increases the rate of ablation during periods of glacial retreat. This forms a discontinuous system of the Earth's temperature and ice-volume in which we find a stable periodic orbit. This can be interpreted as a intrinsic cycling of the Earth's climate in the absence of Milankovitch forcing.

  16. Atmospheric forcing of sea ice in Hudson Bay during the fall period, 1980-2005

    Science.gov (United States)

    Hochheim, K. P.; Barber, D. G.

    2010-05-01

    The principal objective of this study is to describe the autumn sea ice regime of Hudson Bay in the context of atmospheric forcing from 1980 to 2005. Both gridded Canadian Ice Service (CIS) data and Passive Microwave (PMW) data are used to examine the freezeup period for weeks of year (WOY) 43-52. Sea ice concentration (SIC) anomalies reveal statistically significant trends, ranging from -23.3% to -26.9% per decade, during WOY 43-48 using the CIS data and trends ranging from -12.7% to -16.8% per decade during WOY 45-50 using the PMW data. Surface air temperature (SAT) anomalies are highly correlated with SIC anomalies (r2 = 0.52-0.72) and with sea ice extents (r2 = 0.53-0.72). CIS data show that mean sea ice extents based on SICs ≥80% (consolidated ice) have decreased by 1.05 × 105 to 1.17 × 105 km2 for every 1°C increase in temperature in late November; PMW data show similar results. Regression analysis between SAT and standardized climate indices over the 1951-2005 period show that the East Pacific/North Pacific index is highly predictive of interannual SATs followed by the North Atlantic Oscillation and Arctic Oscillation indices. The data show that the Hudson Bay area has recently undergone a climate regime shift, in the mid 1990s, which has resulted in a significant reduction in sea ice during the freezeup period and that these changes appear to be related to atmospheric indices.

  17. Establishment and validation of standardized animal models of spinal cord injury by normal external force-caused fracture dislocation

    Institute of Scientific and Technical Information of China (English)

    Weibing Shuang; Qiang Liu; Shoubin Jiao; Yang Yang

    2011-01-01

    The duplication of animal models plays a key role in spinal cord injury research; however, there has been limited study into normal, external force-derived fracture dislocation. This study adopted experimental devices, designed in-house, to construct standardized ventral and dorsal spinal cord injury animal models of 6 g and 17 g falling from a height of 2, 4, and 10 cm, and 15, 30 or 50 g transversal compression on the spinal cord. The results showed that gradual increases in the degree of histopathological injury led to decreased Tarlov and Basso, Beattie and Bresnahan scores for the behavioral test, and increased Ashworth scores for the hind limb. Furthermore, there was a gradual decline in the slope test in the rats with dorsal spinal cord injury that correlated to increases in the falling substance weight or falling height. Similar alterations were observed in the ventral spinal cord injured rats, proportional to the increase in compression weight. Our experimental findings indicate that the standardized experimental rat models of dorsal and ventral spinal cord injury are stable, reliable and reproducible.

  18. Chaotic dynamics and thermodynamics of periodic systems with long-range forces

    Science.gov (United States)

    Kumar, Pankaj

    Gravitational and electromagnetic interactions form the backbone of our theoretical understanding of the universe. While, in general, such interactions are analytically inexpressible for three-dimensional infinite systems, one-dimensional modeling allows one to treat the long-range forces exactly. Not only are one-dimensional systems of profound intrinsic interest, physicists often rely on one-dimensional models as a starting point in the analysis of their more complicated higher-dimensional counterparts. In the analysis of large systems considered in cosmology and plasma physics, periodic boundary conditions are a natural choice and have been utilized in the study of one dimensional Coulombic and gravitational systems. Such studies often employ numerical simulations to validate the theoretical predictions, and in cases where theoretical relations have not been mathematically formulated, numerical simulations serve as a powerful method in characterizing the system's physical properties. In this dissertation, analytic techniques are formulated to express the exact phase-space dynamics of spatially-periodic one-dimensional Coulombic and gravitational systems. Closed-form versions of the Hamiltonian and the electric field are derived for single-component and two-component Coulombic systems, placing the two on the same footing as the gravitational counterpart. Furthermore, it is demonstrated that a three-body variant of the spatially-periodic Coulombic or gravitational system may be reduced isomorphically to a periodic system of a single particle in a two-dimensional rhombic potential. The analytic results are utilized for developing and implementing efficient computational tools to study the dynamical and the thermodynamic properties of the systems without resorting to numerical approximations. Event-driven algorithms are devised to obtain Lyapunov spectra, radial distribution function, pressure, caloric curve, and Poincare surface of section through an N

  19. Dynamics and ‘normal stress’ evaluation of dilute suspensions of periodically forced prolate spheroids in a quiescent Newtonian fluid at low Reynolds numbers

    Indian Academy of Sciences (India)

    K Madhukar; P V Kumar; T R Ramamohan; I S Shivakumara

    2010-12-01

    The problem of determining the force acting on a particle in a fluid where the motion of the fluid and the particle is given has been considered in some detail in the literature. In this work, we propose an example of a new class of problems where, the fluid is quiescent and the effect of an external periodic force on the motion of the particle is determined at low non-zero Reynolds numbers. We present an analysis of the dynamics of dilute suspensions of periodically forced prolate spheroids in a quiescent Newtonian fluid at low Reynolds numbers including the effects of both convective and unsteady inertia. The inclusion of both forms of inertia leads to a nonlinear integro – differential equation which is solved numerically for the velocity and displacement of the individual particle. We show that a ‘normal stress’ like parameter can be evaluated using standard techniques of Batchelor. Hence this system allows for an experimentally accessible measurable macroscopic parameter, analogous to the ‘normal stress’, which can be related to the dynamics of individual particles. We note that this ‘normal stress’ arises from the internal fluctuations induced by the periodic force. In addition, a preliminary analysis leading to a possible application of separating particles by shape is presented. We feel that our results show possibilities of being technologically important since the ‘normal stress’ depends strongly on the controllable parameters and our results may lead to insights in the development of active dampeners and smart fluids. Since we see complex behaviour even in this simple system, it is expected that the macroscopic behaviour of such suspensions may be much more complex in more complex flows.

  20. Hospital expenditure as a major driver of nurse labour force participation: evidence from a 10-year period in Canada.

    Science.gov (United States)

    Vujicic, Marko; Onate, Kanecy; Laporte, Audrey; Deber, Raisa

    2011-05-01

    This paper examines trends in the nursing labour market in Canada over a period of dramatic fluctuations in hospital expenditures. We add to previous analysis that covered the period 1991-1996 and use Census data from 2001 to examine the relationship between hospital expenditure and nurse labour force participation. We find that shifts in labour force participation over the period 1991-2001 had a significant impact on the nursing supply in Canada. Individuals who were trained in nursing but were working outside the profession in 1996 because of budgetary reductions and layoffs in hospitals had largely been reabsorbed back into nursing jobs by 2001. Our analysis provides further empirical evidence that the labour force participation among individuals trained in nursing is driven to a large extent by demand-side factors.

  1. Evaluation of closure strategies for a periodically-forced Duffing oscillator with slowly modulated frequency subject to Gaussian white noise

    Science.gov (United States)

    Yalim, Jason; Welfert, Bruno D.; Lopez, Juan M.

    2017-03-01

    The response of a Duffing oscillator subject to a periodic forcing with slowly and stochastically modulated frequency is analyzed numerically. The results of both moment and cumulant-based stochastic reductions are compared to Monte Carlo simulations. It is shown how the explicit characterization of higher-order central moments of the (Gaussian) noise source and the periodic nature of the forcing enable a reliable reduction strategy providing a faithful description of the mean behavior of stochastic solutions. The reduced model is then used to illustrate how a large noise level and fast frequency drift may combine to sustain a strong response that is normally associated to resonance in the noiseless static case.

  2. The CSIRO Mk3L climate system model version 1.0 – Part 2: Response to external forcings

    Directory of Open Access Journals (Sweden)

    S. J. Phipps

    2012-05-01

    Full Text Available The CSIRO Mk3L climate system model is a coupled general circulation model, designed primarily for millennial-scale climate simulation and palaeoclimate research. Mk3L includes components which describe the atmosphere, ocean, sea ice and land surface, and combines computational efficiency with a stable and realistic control climatology. It is freely available to the research community. This paper evaluates the response of the model to external forcings which correspond to past and future changes in the climate system.

    A simulation of the mid-Holocene climate is performed, in which changes in the seasonal and meridional distribution of incoming solar radiation are imposed. Mk3L correctly simulates increased summer temperatures at northern mid-latitudes and cooling in the tropics. However, it is unable to capture some of the regional-scale features of the mid-Holocene climate, with the precipitation over Northern Africa being deficient. The model simulates a reduction of between 7 and 15% in the amplitude of El Niño-Southern Oscillation, a smaller decrease than that implied by the palaeoclimate record. However, the realism of the simulated ENSO is limited by the model's relatively coarse spatial resolution.

    Transient simulations of the late Holocene climate are then performed. The evolving distribution of insolation is imposed, and an acceleration technique is applied and assessed. The model successfully captures the temperature changes in each hemisphere and the upward trend in ENSO variability. However, the lack of a dynamic vegetation scheme does not allow it to simulate an abrupt desertification of the Sahara.

    To assess the response of Mk3L to other forcings, transient simulations of the last millennium are performed. Changes in solar irradiance, atmospheric greenhouse gas concentrations and volcanic emissions are applied to the model. The model is again broadly successful at simulating larger-scale changes in the

  3. Cosmic Rays trajectory reconstruction in the Earth Magnetosphere: External Field models importance during the last solar active period (from 2011 to 2013)

    Science.gov (United States)

    Grandi, Davide; Della Torre, Stefano; Pensotti, Simonetta; Bobik, Pavol; Kudela, Karel; Rancoita, Pier Giorgio; Gervasi, Massimo; Jeroen Boschini, Matteo; Rozza, Davide; La vacca, Giuseppe; Tacconi, Mauro

    Geomagsphere is a backtracing code for Cosmic Rays trajectory reconstruction in the Earth Magnetosphere that has been developed with last models of Internal (IGRF-11) and External (Tsyganenko 1996 and 2005) field components. This backtracing technique was used to separate Primary Cosmic Rays Particles, in case of allowed trajectory, from Secondary particles, in case of forbidden trajectory. We compared Magnetic Field measurements with and without the external field model with satellite data in past periods, in particular GOES (1998) and CLUSTER (2004) data. For both periods TS05 reproduces the magnetc field components with good accuracy. The specificity of the TS05 model, designed for solar storms, was tested comparing it with data taken by CLUSTER during the last solar active period (from 2011 to 2013) During Solar Flares (occurred march and May 2012), the usage of such an external field has a relevavant impact on fraction of AMS-02 cosmic rays identified as trapped and secondary particles, especially in high geomagnetic latitudes, as was expecte by some previous simulations, in comparison with the Internal Field only.

  4. The main features of seasonal variability in the external forcing and dynamics of a deep mountain lake (Redó, Pyrenees

    Directory of Open Access Journals (Sweden)

    David M. LIVINGSTONE

    2000-09-01

    Full Text Available Lake Redó, a dimictic oligotrophic mountain lake, was monitored for two complete years from July 1996 to July 1998. The main seasonal variations in the physical, chemical and biological parameters are described, with special emphasis on the comparison of external forcing (weather and atmospheric deposition with internal lake dynamics. Annual mean air temperature was estimated to be 3.6 °C. The duration of ice cover on the lake was 4.5 months in 1996/97 and 5.8 months in 1997/98. The lake water was very ionpoor (mean annual conductivity 12 μS cm-1; however, ion concentrations in the lake were higher than in the precipitation, the differences being due mainly to Ca2+ and bicarbonates originating in the catchment. NH4 + was the main ion in the precipitation, with an average concentration of 17 μM, while in the lake it was always below 3 μM. However, the concentration of dissolved inorganic nitrogen always exceeded that of soluble reactive phosphorus by two or three orders of magnitude, so the latter is likely to be the limiting nutrient for phytoplankton growth. Four main production episodes were identified, occurring during spring and autumn overturn, in the upper hypolimnion during summer stratification, and under the ice at the beginning of the ice-covered period. The highest chlorophyll-a concentrations (1.2-2.2 μg l-1 were attained during spring overturn; concentrations of chlorophyll-c were high during both spring and autumn overturn, while chlorophyll-b was comparatively important in the upper hypolimnion during the stratification period. Daphnia pulicaria was the most abundant macrozooplankton species; its abundance was highest during the icecovered period, when its biomass was comparable to the measured sestonic particulate carbon concentration. The Daphnia maximum was associated with higher concentrations of NH4 + and dissolved organic carbon, suggesting that it may play an important role in the pelagic biogeochemical compartment of

  5. Seasonal and Interannual Fast-Ice Variability from MODIS Surface-Temperature Anomalies, and its Link to External Forcings in Atka Bay, Antarctica

    Science.gov (United States)

    Paul, S.; Hoppmann, M.; Willmes, S.; Heinemann, G.

    2016-12-01

    Around Antarctica, sea ice is regularly attached to coastal features. These regions of mostly seasonal fast ice interact with the atmosphere, ocean and coastal ecosystem in a variety of ways. The growth and breakup cycles may depend on different factors, such as water- and air temperatures, wind conditions, tides, ocean swell, the passage of icebergs and the presence of nearby polynyas. However, a detailed understanding about the interaction between these factors and the fast-ice cycle is missing. In order to better understand the linkages between general fast-ice evolution and external forcing factors, we present results from an observational case study performed on the seasonal fast-ice cover of Atka Bay, eastern Weddell Sea. The ice conditions in this region are critical for the supply of the German wintering station Neumayer III. Moreover, the fast ice at Atka Bay hosts a unique ecosystem based on the presence of a sub-ice platelet layer and a large emperor penguin colony. While some qualitative characterizations on the seasonal fast-ice cycle in this region exist, no proper quantification was carried out to date. The backbone of this work is a new algorithm, which yields the first continuous time series of open-water fractions from Moderate-Resolution Imaging Spectroradiometer (MODIS) surface temperatures. The open-water fractions are derived from a range of running multi-day median temperature composites, utilizing the thermal footprint of warm open water and thin ice in contrast to cold pack-ice/ice-shelf areas. This unique, and manually validated dataset allows us to monitor changes in fast-ice extent on a near daily basis, for a period of 14 years (2002-2015). In a second step, we combine these results with iceberg observations, data from the meteorological observatory, and auxiliary satellite data in order to identify the main factors governing fast-ice formation and break-up.

  6. Forced vibration and wave propagation in mono-coupled periodic structures

    DEFF Research Database (Denmark)

    Ohlrich, Mogens

    1986-01-01

    This paper describes the wave propagation and vibration characteristics of mono-coupled structures which are of spatially periodic nature. The receptance approach to periodic structure theory is applied to study undamped periodic systems with composite structural elements; particular emphasis...... of the determination of the junction-receptance. The influence of such a disorder is illustrated by a simple example...

  7. Force

    CERN Document Server

    Graybill, George

    2007-01-01

    Forces are at work all around us. Discover what a force is, and different kinds of forces that work on contact and at a distance. We use simple language and vocabulary to make this invisible world easy for students to ""see"" and understand. Examine how forces ""add up"" to create the total force on an object, and reinforce concepts and extend learning with sample problems.

  8. Long Period Tidal Force Variations and Regularities in Orbital Motion of the Earth-Moon Binary Planet System

    CERN Document Server

    Avsyuk, Yu N; 10.1007/s11038-011-9381-8; 10.1007/s11038-011-9381-8

    2012-01-01

    We have studied long period, 206 and 412 day, variations in tidal sea level corresponding to various moon phases collected from five observatories in the Northern and Southern hemispheres. Variations in sea level in the Bay of Fundy, on the eastern Canadian seaboard, with periods of variation 206 days, and 412 days, have been discovered and carefully studied by C. Desplanque and D. J. Mossman (2001, 2004). The current manuscript focuses on analyzing a larger volume of observational sea level tide data as well as on rigorous mathematical analysis of tidal force variations in the Sun-Earth-Moon system. We have developed a twofold model, both conceptual and mathematical, of astronomical cycles in the Sun-Earth-Moon system to explain the observed periodicity. Based on an analytical solution of the tidal force variation in the Sun-Earth-Moon system, it is shown that the tidal force can be decomposed into two components: the Keplerian component and the Perturbed component. The Perturbed component of the tidal force...

  9. [Retrospective Cytogenetic Dose Evaluation. I. Chromosome Aberration Levels in Remote Periods after Acute External Exposure in Different Situations].

    Science.gov (United States)

    Nugs, V Yu; Khvostunov, I K; Goloub, E V; Kozlova, M G; Nadejina, N M; Galstian, I A

    2015-01-01

    Cytogenetic analysis of peripheral blood lymphocyte cultures of 22 persons was performed in remote terms after acute external γ-, γ-β- or γ-neutron irradiation as a result of various accidents using the classical me- thod. The initial dose estimates were obtained using physical calculations, the method of measuring the EPR signal in tooth enamel, according to haematological and/or cytogenetic parameters. The purpose of this study was to obtain evidence about the state of the lymphocyte chromosome apparatus of people approxi- mately 17-50 years after an accidental radiation exposure. In general, elevated levels of chromosome aberra- tions were detected. An average correlation was observed between the atypical chromosome frequency and absorbed dose. It is proposed to use the obtained results in the future to explore the possibility of retrospective dose evaluation on the basis of a special computer program.

  10. On the critical periods of Liénard systems with cubic restoring forces

    Directory of Open Access Journals (Sweden)

    Zhengdong Du

    2004-01-01

    show that for a weak center of type I, at most [(1/2deg(F(x]−1 local critical periods can bifurcate and the maximum number can be reached. For a weak center of type II, the maximum number of local critical periods that can bifurcate is at least [(1/4deg(F(x].

  11. In-Fiber Reflection Mode Interferometer Based on A Long-Period Grating For External Refractive-Index Measurement

    OpenAIRE

    Kim, D.W.; Zhang, Y.; Cooper, K. L.; Wang, Anbo

    2005-01-01

    We present two novel schemes for refractometry based on a long-period fiber grating- (LPG-) based Michelson interferometer. These schemes are designed to overcome the measurement dependence of previously demonstrated LPG-based refractometry on the immersion depth. The first utilizes an unshielded LPG and the second, a shielded one. Both schemes were tested over a certain refractive-index range, and the measurement of glucose concentration in water was experimentally demonstrated. In addition,...

  12. A Multi-Channel Method for Detecting Periodic Forced Oscillations in Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Follum, James D.; Tuffner, Francis K.

    2016-11-14

    Forced oscillations in electric power systems are often symptomatic of equipment malfunction or improper operation. Detecting and addressing the cause of the oscillations can improve overall system operation. In this paper, a multi-channel method of detecting forced oscillations and estimating their frequencies is proposed. The method operates by comparing the sum of scaled periodograms from various channels to a threshold. A method of setting the threshold to specify the detector's probability of false alarm while accounting for the correlation between channels is also presented. Results from simulated and measured power system data indicate that the method outperforms its single-channel counterpart and is suitable for real-world applications.

  13. External injection and acceleration of electron bunch in front of the plasma wakefield produced by a periodic chirped laser pulse

    Science.gov (United States)

    Eslami, Esmaeil; Afhami, Saeedeh

    2017-01-01

    Herein, we present the analytical results on the behavior of the electron bunch injected in front of the plasma wakefield produced by a chirped laser pulse. In particular, a periodic chirped pulse may produce an ultra-relativistic electron bunch with a relatively small energy spread. The electrons are trapped near the region of the first accelerating maximum of the wakefield and are compressed in both the longitudinal and transverse directions (betatron oscillation). Our results are in good agreement with the one-dimensional results recently published.

  14. 二阶非线性方程的强迫概周期振动%FORCED ALMOST PERIODIC OSCILLATION OF SECOND ORDER NONLINEAR EQUATION

    Institute of Scientific and Technical Information of China (English)

    史金麟

    2001-01-01

    In this paper, we consider forced almost periodic oscillation of second order nonlinear equation. Under some conditions, we prove the existence and uniqueness of almost periodic solution and discuss its stability.

  15. [The depressive disorders during the early rehabilitation period following preceding ischemic stroke: the possibilities for the application of the enhanced external counterpulsation method].

    Science.gov (United States)

    Razumov, A N; Éneeva, M A; Kostenko, E V; Bobyreva, S N

    2016-01-01

    The authors present arguments in favour of the necessity to reveal and treat the co-morbid conditions with special reference to depressive disorders in the patients during the early rehabilitation period following preceding ischemic stroke. They demonstrate the importance of the application of non-medicamentous therapy in combination with the standard medicamental treatment. Special emphasis is placed on the analysis of the data obtained during evaluation of the effectiveness of combined therapy with the use of the enhanced external counterpulsation method in the early post-stroke period. It is concluded that the early diagnostics and timely correction of anxio-depressive conditions promotes the efficiency of rehabilitative measures and improves the quality of life of the patients with such disorders.

  16. Tree-ring density variations during the 1450s period of strong volcanic forcing

    Science.gov (United States)

    Esper, Jan; Büntgen, Ulf; Hartl-Meier, Claudia; Oppenheimer, Clive; Schneider, Lea

    2017-04-01

    Ice core based reconstructions of the magnitude and timing of volcanic eruptions are used to force climate models and therefore are of critical importance for assessing the dynamics of the global climate system. The forcing timeseries of the past millennium are punctuated by a few very large volcanic events including a major eruption in the 1450s. This event was originally attributed to the Kuwae caldera in the South Pacific dated to the year 1452. Recent evidence from high-resolution ice core records, however, indicated a shift by six years (to 1458), a change that will fundamentally alter 15th century climate simulations and affect model/proxy comparisons. Here we compile a Northern Hemisphere network of 25 tree-ring maximum latewood density chronologies extending back over the past 650+ years and analyze the 1450s temperature deviations. Warm season temperature reconstructions from these data reveal the spatially most coherent and by far most severe cooling of the 15th century occurred in 1453. Cooling was overall stronger in the Eurasian high latitudes and northwestern North America, and less severe in central and southern Europe. These findings indicate that the original dating of a large eruption in 1452 was correct.

  17. Tuning a PD Controller Based on an SVR for the Control of a Biped Robot Subject to External Forces and Slope Variation

    Directory of Open Access Journals (Sweden)

    João P. Ferreira

    2014-03-01

    The ZMP is calculated by reading four force sensors placed under each of the robot’s feet. The gait implemented in this biped is similar to a human gait, which is acquired and adapted to the robot’s size. The main contribution of this paper is the fine-tuning of the ZMP controller based on the SVR. To implement and test this, the biped robot was subjected to external forces and slope variation. Some experiments are presented and the results show that the implemented gait combined with the correct tuning of the SVR controller is appropriate for use with this biped robot. The SVR controller runs at 0.2 ms, which is about 50 times faster than a corresponding first- order TSK neural-fuzzy network.

  18. Implementation of electro-optic amplitude modulator in the external cavity of semiconductor laser for generation of periodic sates and chaos control

    Directory of Open Access Journals (Sweden)

    Kh Mabhouti

    2016-12-01

    Full Text Available In this paper, by placing the electro optical modulator (EOM into the external cavity of the semiconductor laser (SL and amplitude modulation of the optical feedback, the dynamical variation of the output intensity  of the laser has been studied. This is analyzed numerically via bifurcation and time series diagrams with respect to the applied amplitude modulation index, and modulation voltage frequency of the EOM. It has been shown that, by modulating the amplitude of the optical feedback beam, various changes in the types of the dynamics of  can be observed, and various periodic states can be generated. This makes it possible to receive the desired dynamics without any variations in the main parameters of the SL. Also, in present study, a method of chaos control in the SL has been presented based on EOM in the external cavity. The obtained results confirm that based on this method the chaotic dynamics can be controlled single-periodic dynamics

  19. Force-time curve characteristics and hormonal alterations during an eleven-week training period in elite women weightlifters.

    Science.gov (United States)

    Haff, G Gregory; Jackson, Janna R; Kawamori, Naoki; Carlock, Jon M; Hartman, Michael J; Kilgore, J Lon; Morris, Robert T; Ramsey, Michael W; Sands, William A; Stone, Michael H

    2008-03-01

    The purpose of this investigation was to study the effects of an 11-week training period performed by female weightlifters. Two weeks before this investigation, baseline measures for total testosterone, cortisol, and testosterone:cortisol ratio were collected. The 11-week training program consisted of the core exercises (i.e., clean, clean and jerk, and snatch) and other supplemental exercises (i.e., clean pull, snatch pull, squat, and front squat). Hormonal, isometric, and dynamic middle thigh pull force-time curve characteristics were assessed biweekly throughout the duration of the investigation, whereas volume load and training intensity were assessed weekly throughout the investigation. The testosterone:cortisol ratio of the baseline (1.19 +/- 0.64) was significantly different from the ratio of weeks 1 (0.67 +/- 0.36) and 9 (0.94 +/- 0.66). When the week-to-week values were compared, week 1 (0.67 +/- 0.36) was significantly different (P < 0.05; eta = 0.84) from week 3 (1.06 +/- 0.54). A very strong correlation (r = -0.83; r = 0.69) was found between the percentage change of the testosterone:cortisol ratio and volume load from weeks 1 to 11. Moderate to very strong correlations were noted between the percentage change in volume load and isometric peak force, peak force during the 30% isometric peak force trial, and peak force during the 100-kg trial during the 11 weeks of training. The primary finding of this study was that alterations in training volume load can result in concomitant changes in the anabolic-to-catabolic balance, as indicated by the testosterone:cortisol ratio, and the ability to generate maximal forces.

  20. The application of an external wrist extension force reduces electromyographic activity of wrist extensor muscles during gripping.

    NARCIS (Netherlands)

    Elk, N. van; Faes, M.C.; Degens, H.; Kooloos, J.G.M.; Lint, J.A. de; Hopman, M.T.E.

    2004-01-01

    STUDY DESIGN: Experimental repeated-measures study. OBJECTIVE: To investigate the effect of different extension forces applied to the palm of the hand on electromyographic (EMG) activity of the wrist extensor muscles during hand gripping. BACKGROUND: Lateral epicondylitis is usually caused by repeti

  1. The Effects of Dominant Driving Forces on Summer Precipitation during Different Periods in Beijing

    Directory of Open Access Journals (Sweden)

    Fuxing Li

    2017-02-01

    Full Text Available Wavelet analysis methods (CWT, XWT, WTC were employed to evaluate the impact of dominant climatic driving factors on summer precipitation in the Beijing area based on monthly precipitation data of Beijing ranging from 1880 to 2014. The two climatic driving factors, i.e., the East Asian summer monsoon (EASM and the Northern Limit of Western Pacific Subtropical High (NWPSH were considered in particular. The relationships between summer precipitation and EASM/NWPSH were also examined. The results revealed similar periods in low-frequency oscillation (76–95 years and mid-range frequency oscillation (32–60 years for the summer precipitation in the Beijing area and EASM/NWPSH. The summer precipitation correlated positively with the NWPSH and EASM, especially for periods of 43 years and 33 years, respectively. This indicates that summer precipitation during 1880–1960 and during the years after 1960 was significantly affected by NWPSH and EASM, respectively. Based on the periodic change of 33 years for both summer precipitation and EASM, heavy precipitation can be expected to occur again in Beijing at approximately 2026. Understanding the relationships between summer precipitation and climatic factors is of significant importance for precipitation predictions and water resource variations in the Beijing area.

  2. DYNAMIC MODEL OF CROP GROWTH SYSTEM AND NUMERICAL SIMULATION OF CROP GROWTH PROCESS UNDER THE MULTI-ENVIRONMENT EXTERNAL FORCE ACTION

    Institute of Scientific and Technical Information of China (English)

    李自珍; 王万雄; 徐彩琳

    2003-01-01

    According to the biomechanic theory and method, the dynamic mechanism of crop growth under the external force action of multi-environment factors (light, temperature, soil and nutrients etc.) was comprehensively explored. Continuous-time Markov (CTM) approach was adopted to build the dynamic model of the crop growth system and the simulated numerical method. The growth rate responses to the variation of the external force and the change of biomass saturation value were studied. The crop grew in the semiarid area was taken as an example to carry out the numerical simulation analysis, therefore the results provide the quantity basis for the field management. Comparing the dynamic model with the other plant growth model, the superiority of the former is that it displays multi-dimension of resource utilization by means of combining macroscopic with microcosmic and reveals the process of resource transition. The simulation method of crop growth system is advanced and manipulated. A real simulation result is well identical with field observational results.

  3. Priming Silicic Giant Magma Bodies: Finding Evidence for Internal Forcing Versus External Triggering of Supereruptions by Phase Equilibria Modeling.

    Science.gov (United States)

    Tramontano, S.; Gualda, G. A. R.; Ghiorso, M. S.; Kennedy, B.

    2015-12-01

    It is important to understand what triggers silicic eruptions because of the implications for modern-day systems. The goal of this project is to use phase equilibria modeling (i.e. rhyolite-MELTS) to determine to what extent magmas within the crust are induced to erupt due to external triggers (e.g. earthquakes; new magma injection; neighboring eruptions) and to what extent they naturally evolve to a point where eruption is inevitable (e.g. by fluid exsolution and decrease in magma strength and density). Whole-rock compositions from four rhyolite tuffs across the globe associated with large or supereruptions (Mamaku Tuff, New Zealand; Peach Spring Tuff, SW USA; early and late-erupted Bishop Tuff, California; and Toba Tuff, Indonesia) are studied using rhyolite-MELTS modeling. Key physical properties of magma are strongly affected by the initial volatile content due to fluid exsolution. By running simulations with varying water contents, we can track the evolution of fluid exsolution during crystallization. Isobaric (constrained temperature change at constant pressure) and isochoric (constrained temperature change at constant volume) models were run for the four compositions. In constrained-pressure scenarios, fluid is free to exsolve as crystallization proceeds, and the total system volume can increase or decrease accordingly; this would require deformation of the surrounding crust to accommodate the magma volume change. In constrained-volume scenarios, bubble exsolution is limited to the volume change due to crystallization; in this case, pressure can decrease or increase (if bubbles are absent or present). For fixed-pressure scenarios, fluid exsolution is more extensive and leads to internal triggering, at least for fluid-saturated conditions; external triggering is more likely in fluid-undersaturated conditions. For fixed-volume scenarios, none of the systems cross a fragmentation threshold for the crystal contents typically observed in natural pumice. If

  4. The forced sound transmission of finite ribbed plates, investigating the influence of point connections and periodicity

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2015-01-01

    Many engineering structures consist of plates being stiffened by ribs. The ribs can be connected to the plate in a line connection (welded or glued) or in point connections (screwed). It is well known that the rib stiffeners can significantly change the vibration field and the radiation behavior...... been derived, using a variational technique based on integral-differential equations of the fluid loaded plate. In this way an optimal solution is derived, using a very simple initial guess of the vibration field. The finite plate is assumed being mounted in a rigid baffle. The approach is based...... the model. The influence of point versus line connections, as well as periodicity effects, is investigated....

  5. Investigation of Domain Wall Velocity to External Fields for High-Quality Waveguide-Type Periodically Poled LiNbO3 Fabrication

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The Ti-doped waveguide-type periodically poled LiNbO3 (PPLN) were fabricated and the dependence of domain wall velocity on an external field applied for domain inversion was investigated. The whole polarization reversal process was computer-controlled to regulate domain wall expansion at a feedback time shorter than 5 μs. The coercive voltage and several values of excess voltage were applied on 500 μm-thick wafers serially connected to a 1-MOhm external resistor which had an effect of the poling current reduction, i.e. the deceleration of domain wall expansion. The domain wall velocity is sensitive to the poling voltage, precisely speaking, to the excess voltage. The domain wall velocities were 28.70, 16.02 and 5.75 μm·s-1 under poling field of 23.5, 22.0 and 21.0 kV·mm-1, respectively. Moreover, average duty cycle of PPLN is about 49.93%.

  6. Computationally exact methods for stochastic periodic dynamics: Spatiotemporal dispersal and temporally forced transmission.

    Science.gov (United States)

    Ross, J V

    2010-01-07

    The dynamics of many diseases and populations possess distinct recurring phases. For example, many species breed only during a subset of the year and the infection dynamics of many pathogens have transmission rates that vary with season. Here I investigate computational methods for studying transient and long-term behaviour of stochastic models which have periodic phases-several different potential techniques for studying long-term behaviour will be contrasted. I illustrate the results with two studies: The first is of a spatially realistic metapopulation model of malleefowl (Leipoa ocellata), a species which disperses only during a quarter of the year; this model is used to highlight the advantages and disadvantages of the particular methods presented. The second study is of a model for disease dynamics which incorporates seasonality in both the rate of within-population transmission and also in the rate of transmission effected via aerosol importation. This model has applications to studying disease invasion and persistence in captive-breeding populations. We demonstrate, via comparison to appropriately matched models with constant transmission rates and also no aerosol transmission, that seasonality and aerosol importation may alter control choices, with possibly an increase in the threshold population size for local control surveillance, transfer of importance to limiting aerosol transmission, and the use of temporally targetted surveillance. The methodology presented is the gold-standard for dealing with many phased processes in ecology and epidemiology, but its application is limited to systems of small size.

  7. Influence of long-period pesticide force on genetic polymorphism of wolf spider Pardosa pseudoannulata (Lycosidae: Araneae)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Wolf spiders are predators in large quantities in the fields. How wolf spiders keep their dominant species status under long-period pesticide force? To answer this question, eight geographical populations of Pardosa pseudoannulata were used as materials to test the influence of geographical habitats on their genomic DNA polymorphism. The RAPD pattern showed polymorphic variations among and within different populations. Total 84 bands amplified by 10 random primers, of which 62 (73.81% ) are polymorphic, were generated from 55 individuals of eight geographical populations. Meanwhile, Shannon's index (Ho = 0.5177) showed a rich genetic diversity of P. pseudoannulata, and most of the genetic variation (64.24%) was found within populations. Multiple regression analysis suggested that it is the climatic variation (such as annual average temperature etc. ) that results in adaptive eco-geographic differentiation, and it is the long-period pesticide force that speeds up the genetic differentiation of P. pseudoannulata which changed the genetic diversity of the population.

  8. The Dynamics of a Periodically Forced Cortical Microcircuit, With an Application to Schizophrenia

    Science.gov (United States)

    Vierling-Claassen, Dorea; Kopell, Nancy

    2009-01-01

    Synchronous neural activity in the brain in the gamma and beta frequency bands (50-70 Hz)is thought to be important for sensory processing and is altered in schizophrenia. In a previous study, gamma/beta click-train auditory stimuli were used to probe cortical oscillatory activity in control and schizophrenic subjects. We found that control subjects exhibited preferential 40 Hz responses to both 20 and 40 Hz stimulations, while schizophrenic subjects had enhanced 20 Hz responses to the same stimuli [D. Vierling-Claassen, P. Siekmeier, S. Stufflebeam, and N. Kopell, J. Neurophysiol., 99 (2008), p. 2656]. High-dimensional computational network models constructed previously, which were based on evidence of altered inhibition in schizophrenia, numerically generated the entrainment behaviors observed experimentally. However, questions regarding the dynamic origin of model behaviors remained. It was not clear that the 20 Hz response to 40 Hz drive in the schizophrenic network was robust to parameter changes, which would be necessary for the predicted mechanism to explain data from a heterogeneous subject population. In the schizophrenic network we observed 30 Hz drive responses with a frequency component below 30 Hz, for which no analogue appeared in experimental data, and wondered if these were dynamically distinct from the modeled 20 Hz response to 40 Hz drive. We also wished to explore the role of background noise in model behavior. To address these questions, we consider a system of two mutually coupled oscillators representative of neural cells, driven periodically in the gamma/beta frequency band. We show that there is a one-parameter family of discontinuous discrete maps, whose dynamics clarifies issues of robustness, classifies entrainment patterns, and provides insight into the role of excitatory noise.

  9. Predictability of Forced Lorenz Systems

    Science.gov (United States)

    Li, Baosheng; Ding, Ruiqiang; Li, Jianping; Zhong, Quanjia

    2017-04-01

    Based on the nonlinear local Lyapunov exponent (NLLE) approach, the influences of external forcing on the predictability are studied in the Lorenz systems with constant and quasi-periodic forces in this paper. The results indicate that for the Lorenz systems with constant and quasi-periodic forces, their predictability limits increase with the forcing strength. With the same magnitude and different directions, the constant or quasi-periodic forcing shows different effects on the predictability limit in the Lorenz system, and these effects become significant with the increase of the forcing strength. Generally speaking, the positive forcing leads to a higher predictability limit than the negative forcing. Therefore, when we think about the effects of positive and negative elements and phases in the atmosphere and ocean research, the predictability problems driven by different phases should be considered separately. In addition, the influences of constant and quasi-periodic forces on the predictability are different in the Lorenz system. The effect of the constant forcing on the predictability is mainly reflected in the linear phase of error growth, while the nonlinear phase should also be considered for the situation of the quasi-periodic forcing. The predictability limit of the system under constant forcing is longer than the system under quasi-periodic forcing. These results based on simple chaotic model could provide insight into the studies of the actual atmosphere predictability.

  10. “Coloniality of power” in East Central Europe: external penetration as internal force in post-socialist Hungarian politics

    Directory of Open Access Journals (Sweden)

    Agnes Gagyi

    2016-08-01

    Full Text Available Joining a series of analyses of effects of othering, orientalism, or coloniality in East Central Europe, the paper asks how long-term structural-ideological effects of global hierarchies, as reflected in post-colonial contexts by the term “coloniality of power,” can be conceptualized for East Central Europe. In a case study of political polarization in post-socialist Hungary,it examines the effects of global integration,  claiming that two dominant economic-political blocks formed along a division of vertical alliances related to integration with either Western or national capital. From those positions, they developed divergent political ideologies of development: modernization through Western integration, versus the protection of “national” wealth from Western capital and its local allies. While both propagated capitalist integration, they each needed to develop ideologies that appealed to electorates suffering the costs of integration. One framing of developmentalist emancipation promised Western modernity through rejection of popular, backward characteristics of the country, including nationalism. The other promised advancement in the global hierarchy through overcoming internal and external enemies of national development. These two, mutually reinforcing ideological positions, which I call“democratic antipopulism” and “antidemocratic populism,” denied the contradiction between elites’ and workers’ interest and perpetuated existing global hierarchies. Within the wider debate over cross-contextual applications of the notion of “coloniality of power,” and of emancipative efforts born from the “colonial wound,” the paper emphasizes the significance of the structural conditions, positions and alliances within which experiences of global domination are born and mobilized.

  11. Use of induced acceleration to quantify the (de)stabilization effect of external and internal forces on postural responses.

    Science.gov (United States)

    van Asseldonk, Edwin H F; Carpenter, Mark G; van der Helm, Frans C T; van der Kooij, Herman

    2007-12-01

    Due to the mechanical coupling between the body segments, it is impossible to see with the naked eye the causes of body movements and understand the interaction between movements of different body parts. The goal of this paper is to investigate the use of induced acceleration analysis to reveal the causes of body movements. We derive the analytical equations to calculate induced accelerations and evaluate its potential to study human postural responses to support-surface translations. We measured the kinematic and kinetic responses of a subject to sudden forward and backward translations of a moving platform. The kinematic and kinetics served as input to the induced acceleration analyses. The induced accelerations showed explicitly that the platform acceleration and deceleration contributed to the destabilization and restabilization of standing balance, respectively. Furthermore, the joint torques, coriolis and centrifugal forces caused by swinging of the arms, contributed positively to stabilization of the Center of Mass. It is concluded that induced acceleration analyses is a valuable tool in understanding balance responses to different kinds of perturbations and may help to identify the causes of movement in different pathologies.

  12. Particle motion in a periodic driving flow. The role of added mass force and the finite size of particles

    Science.gov (United States)

    Ruiz Chavarria, Gerardo; Lopez Sanchez, Erick Javier

    2016-11-01

    The motion of particles in a fluid is an open problem. The main difficulty arises from the fact that hydrodynamical forces acting on a particle depend on the flow properties. In addition, the form and the size of particles must be taken into account. In this work we present numerical results of the particle transport in a periodic driving flow in a channel flushing into an open domain. To study the transport of particles we solve the equation of motion for a spherical particle in which we include the drag, the gravity, the buoyancy, the added mass and the history force. Additionally we include the corrections for a particle of finite size. For solving this equation a knowledge of the velocity field is required. To obtain the velocity field we solve the Navier Stokes and the continuity equations with a finite volume method. In the flow under study a vorticity dipole and a spanwise vortex are present, both have an important influence on the motion of particles. The dipole enhances displacement of particles because flow between vortices behaves like a jet and the spanwise vortex produces the lifting and deposition of particles from/to the bottom. We observe clustering of particles both into the channel and in the open domain as observed in coastal systems. The authors acknowledge DGAPA-UNAM by support under project PAPIIT IN115315 "Ondas y estructuras coherentes en dinámica de fluidos".

  13. EXISTENCE AND UNIQUENESS OF ALMOST PERIODIC SOLUTIONS FOR FORCED RAYLEIGH EQUATIONS%强迫Rayleigh方程概周期解的存在性和唯一性

    Institute of Scientific and Technical Information of China (English)

    陈凤德

    2001-01-01

    The aim of this paper is to investigate the existence and uniqueness of almost periodic solutions for the forced Rayleigh equation. By combining the theory of exponential dichotomies with Liapunov functions, we obtain an interesting result on the existence of almost periodic solutions.

  14. A NUMERICAL PERTURBATION EXPANSION METHOD FOR THE SOLUTION OF A LIENARD-TYPE INITIAL-VALUE PROBLEM WITH PERIODIC DECAYING FORCING TERM

    Institute of Scientific and Technical Information of China (English)

    张荣; 何雪明

    2004-01-01

    A numerical perturbation expansion method is developed, analysed and implemented for the numerical solution of a second-order initial-value problem. The differential equation in this problem exhibits cubic damping, a cubic restoring force and a decaying forcing-term which is periodic with constant frequency. The method is compared with the numerical method by Twizell [1]. In fact, the later is first perturbation approximate solution in the present paper.

  15. EXISTENCE AND UNIQUENESS OF STRONG PERIODIC SOLUTION OF THE EVOLUTION SYSTEM DESCRIBING GEOPHYSICAL FLOW PART I: IN BOUNDED DOMAINS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The existence and uniqueness of a strong periodic solution of the evolution system describing geophysical flow in bounded domains of RN(N = 3, 4) are proven if external forces are periodic in time and sufficiently small.

  16. Ultrasensitive hysteretic force sensing with parametric nonlinear oscillators

    Science.gov (United States)

    Papariello, Luca; Zilberberg, Oded; Eichler, Alexander; Chitra, R.

    2016-08-01

    We propose a method for linear detection of weak forces using parametrically driven nonlinear resonators. The method is based on a peculiar feature in the response of the resonator to a near resonant periodic external force. This feature stems from a complex interplay among the parametric drive, external force, and nonlinearities. For weak parametric drive, the response exhibits the standard Duffing-like single jump hysteresis. For stronger drive amplitudes, we find a qualitatively new double jump hysteresis which arises from stable solutions generated by the cubic Duffing nonlinearity. The additional jump exists only if the external force is present and the frequency at which it occurs depends linearly on the amplitude of the external force, permitting a straightforward ultrasensitive detection of weak forces. With state-of-the-art nanomechanical resonators, our scheme should permit force detection in the attonewton range.

  17. A model for origin of self-rotation in a protoplanetary cloud under action of exterior periodic force

    Science.gov (United States)

    Tkachova, P. P.; Krot, A. M.

    2009-04-01

    This work investigates condition for origin of increasing rotational disturbance in a gas-liquid protoplanetary cloud under action of a periodic force. The model (based on Reynolds equations [1]) describing self-organization of rotational disturbance of viscous gas-liquid substance into a protoplanetary cloud is proposed. The Reynolds equations as well as continuity equation in cylindrical frame of reference (r, e, z) as basis relations for this analytical model are used. The mean velocity is supposed to be equal to zero from the beginning action of an exterior periodic force. The Reynolds' tensor of turbulent strain of velocity disturbances in a becoming fluid flow is sought for (besides, z-component of velocity disturbance is supposed to be equal to zero). In assumption that z-components of turbulent strains are equal to zero, the (r, e)-turbulent strain components are found. After all considerations the Reynolds equations and continuity one (in the cylindrical coordinate system) are reduced to the system of two differential equations in partial derivatives relatively to (r, e)-cylindrical components of turbulent strain of velocity disturbance. A common solution of these two equations permits us to reduce this task to solution of one differential equation relatively to (r, e)-turbulent strain. This homogeneous differential equation is solved with usage of the variables separation method. As a result, a superposition of two cosine's and sine's waves gives us (r, e)-turbulent strain wave with an elliptic (or circular) polarization. Moreover, this paper shows that amplitude of cosine-wave as well as sine-wave is an increasing function as r**(n**2-2). This paper finds that oscillations are intensified with growing a frequency of becoming oscillations. The computational experiments based on STAR-CD package [2] confirm the main analytical statements of the proposed model for becoming self-rotation in a gas-liquid protoplanetary cloud. This work develops also the

  18. Activities of the Oil Implementation Task Force, reporting period March--August 1991; Contracts for field projects and supporting research on enhanced oil recovery, reporting period October--December 1990

    Energy Technology Data Exchange (ETDEWEB)

    1991-10-01

    Activities of DOE's Oil Implementation Task Force for the period March--August 1991 are reviewed. Contracts for fields projects and supporting research on enhanced oil recovery are discussed, with a list of related publications given. Enhanced recovery processes covered include chemical flooding, gas displacement, thermal recovery, and microbial recovery.

  19. Effect of External Forced Flow and Boiling Film on Heat Transfer of AISI 4140 Steel Horizontal Rod During Direct Quenching%Effect of External Forced Flow and Boiling Film on Heat Transfer of AISI 4140 Steel Horizontal Rod During Direct Quenching

    Institute of Scientific and Technical Information of China (English)

    A H Meysami; R Ghasemzadeh; S H Seyedein; M R Aboutalebi

    2011-01-01

    The effects of rod falling and moving, external flow field, boiling film and radiation were investigated on fluid flow and heat transfer of AISI 4140 steel horizontal rod during direct quenching by mathematical modeling. The flow field and heat transfer in quenching tank were simulated by computational fluid dynamics (CFD) method considering falling and moving of rods during process. Therefore, modeling of flow field was done by a fixed-mesh method for general moving objects equations, and then, energy equation was solved with a numerical approach so that effeet of boiling film heat flux was considered as a source term in energy equation for solid-liquid boundary. Simulated results were verified by comparing with published and experimental data and there was a good agreement between them. Also, the effects of external forced flow and film boiling were investigated on heat flux output, temperature distribution and heat transfer coefficient of rod. Also simulated results determined optimum quenching time for this process.

  20. Periodic solutions of nonlinear vibrating beams

    Directory of Open Access Journals (Sweden)

    J. Berkovits

    2003-01-01

    Full Text Available The aim of this paper is to prove new existence and multiplicity results for periodic semilinear beam equation with a nonlinear time-independent perturbation in case the period is not prescribed. Since the spectrum of the linear part varies with the period, the solvability of the equation depends crucially on the period which can be chosen as a free parameter. Since the period of the external forcing is generally unknown a priori, we consider the following natural problem. For a given time-independent nonlinearity, find periods T for which the equation is solvable for any T-periodic forcing. We will also deal with the existence of multiple solutions when the nonlinearity interacts with the spectrum of the linear part. We show that under certain conditions multiple solutions do exist for any small forcing term with suitable period T. The results are obtained via generalized Leray-Schauder degree and reductions to invariant subspaces.

  1. Report on equipment availability for the ten-year period, 1967--1976. A report of the Equipment Availability Task Force of the Prime Movers Committee

    Energy Technology Data Exchange (ETDEWEB)

    Haueter, R.L.; Haddad, E.E.; Brickell, M.C.; Poeppelmeier, V.E.; Prestele, J.A.; Roettger, R.W.; Thompson, W.H.; Weiser, J.L.; Whooley, J.P.

    1977-12-01

    Data are tabulated on the availability and outage rates for all types of electric power generating plants operating in the U.S. during the period from 1967 through 1976. The power plant types include fossil-fueled, nuclear, hydro, and pumped storage. The outages include those scheduled for maintenance and normal operation and unplanned or forced outages. (LCL)

  2. 27.3-day and Average 13.6-day Periodic Oscillations in the Earth's Rotation Rate and Atmospheric Pressure Fields Due to Celestial Gravitation Forcing

    Institute of Scientific and Technical Information of China (English)

    LI Guoqing; ZONG Haifeng; ZHANG Qingyun

    2011-01-01

    Variation in length of day of the Earth (LOD equivalent to the Earth's rotation rate) versus change in atmospheric geopotential height fields and astronomical parameters were analyzed for the years 1962-2006.This revealed that there is a 27.3-day and an average 13.6-day periodic oscillation in LOD and atmospheric pressure fields following lunar revolution around the Earth. Accompanying the alternating change in celestial gravitation forcing on the Earth and its atmosphere, the Earth's LOD changes from minimum to maximum,then to minimum. and the atmospheric geopotential height fields in the tropics oscillate from low to high,then to low. The 27.3-day and average 13.6-day periodic atmospheric oscillation in the tropics is proposed to be a type of strong atmospheric tide, excited by celestial gravitation forcing. A formula for a Tidal Index was derived to estimate the strength of the celestial gravitation forcing, and a high degree of correlation was found between the Tidal Index determined by astronomical parameters, LOD, and atmospheric geopotential height. The reason for the atmospheric tide is periodic departure of the lunar orbit from the celestial equator during lunar revolution around the Earth. The alternating asymmetric change in celestial gravitation forcing on the Earth and its atmosphere produces a "modulation" to the change in the Earth's LOD and atmospheric pressure fields.

  3. Martial arts fall techniques reduce hip impact forces in naive subjects after a brief period of training.

    Science.gov (United States)

    Weerdesteyn, V; Groen, B E; van Swigchem, R; Duysens, J

    2008-04-01

    Hip fractures are among the most serious consequences of falls in the elderly. Martial arts (MA) fall techniques may reduce hip fracture risk, as they are known to reduce hip impact forces by approximately 30% in experienced fallers. The purpose of this study was to investigate whether hip impact forces and velocities in MA falls would be smaller than in a 'natural' fall arrest strategy (Block) in young adults (without any prior experience) after a 30-min training session in sideways MA fall techniques. Ten subjects fell sideways from kneeling height. In order to identify experience-related differences, additional EMG data of both fall types were collected in inexperienced (n=10) and experienced fallers (n=5). Compared to Block falls, MA falls had significantly smaller hip impact forces (-17%) and velocities (-7%). EMG results revealed experience-related differences in the execution of the MA fall, indicative of less pronounced trunk rotation in the inexperienced fallers. This may explain their smaller reduction of impact forces compared to experienced fallers. In conclusion, the finding that a substantial reduction in impact forces can be achieved after a short training in MA techniques is very promising with respect to their use in interventions to prevent fall injuries.

  4. Impact of external resistance and maximal effort on force-velocity characteristics of the knee extensors during strengthening exercise: a randomized controlled experiment.

    Science.gov (United States)

    Van Roie, Evelien; Bautmans, Ivan; Boonen, Steven; Coudyzer, Walter; Kennis, Eva; Delecluse, Christophe

    2013-04-01

    It remains controversial whether maximal effort attained by high external resistance is required to optimize muscle adaptation to strengthening exercise. Here, we compared different training protocols reaching maximal effort with either high-resistance (HImax, 80% of 1-repetition maximum [1RM]) or low-resistance (LOmax, ≤40% 1RM). Thirty-six young volunteers were randomly assigned to 9 weeks of leg extension training at either HImax (1 set of 10-12 repetitions at 80% 1RM), LO (1 set of 10-12 repetitions at 40% 1RM, no maximal effort), or LOmax (1 set of 10-12 repetitions at 40% 1RM, preceded [no rest] by 60 repetitions at 20-25% 1RM). Knee extension 1RM was measured preintervention and postintervention and before the 7th, 13th, and 19th training sessions. Preintervention and postintervention, knee extensor static (PTstat) and dynamic (PTdyn) peak torque, maximal work (MW), and speed of movement at 20% (S20), 40% (S40), and 60% (S60) of PTstat were recorded with a Biodex dynamometer. All the groups showed a significant increase in 1RM, with a greater improvement in HImax from the 13th session on (p < 0.05). The HImax was the only group that significantly increased PTstat (+7.4 ± 8.1%, p = 0.01). The LOmax showed a significantly greater increase in S20 (+6.0 ± 3.2%), PTdyn (+9.8 ± 5.6%), and MW (+15.1 ± 10.6%) than both HImax and LO (p = 0.044 for S20, p = 0.030 for PTdyn, p = 0.025 for MW) and was the only group that increased in S40 (+7.7 ± 9.7%, p = 0.032). In conclusion, significant differences between HImax and LOmax on force-velocity characteristics of the knee extensors were found, although maximal effort was achieved in both training regimens. Thus, LOmax may not be considered as a replacement for HImax but rather as an alternative with different training-specific adaptations.

  5. Martial arts fall techniques reduce hip impact forces in naive subjects after a brief period of training.

    NARCIS (Netherlands)

    Weerdesteijn, V.G.M.; Groen, B.E.; Swigchem, R. van; Duysens, J.

    2008-01-01

    Hip fractures are among the most serious consequences of falls in the elderly. Martial arts (MA) fall techniques may reduce hip fracture risk, as they are known to reduce hip impact forces by approximately 30% in experienced fallers. The purpose of this study was to investigate whether hip impact fo

  6. Martial arts fall techniques reduce hip impact forces in naive subjects after a brief period of training.

    NARCIS (Netherlands)

    Weerdesteijn, V.G.M.; Groen, B.E.; Swigchem, R. van; Duysens, J.

    2008-01-01

    Hip fractures are among the most serious consequences of falls in the elderly. Martial arts (MA) fall techniques may reduce hip fracture risk, as they are known to reduce hip impact forces by approximately 30% in experienced fallers. The purpose of this study was to investigate whether hip impact

  7. Long-period orbital climate forcing. Cyclostratigraphic studies of Cenozoic continental and marine successions in Europe. Geologica Ultraiectina (297)

    NARCIS (Netherlands)

    Abels, H.A.

    2008-01-01

    Orbital climate forcing is well-known for its strong impact on Earth’s climate as for example the switching from glacial to inter-glacial states in the Late Pleistocene. Typical ‘Milankovitch’ cycles are climatic precession (21.000 years or 21 kyrs), obliquity (41 kyrs), and short and long eccentric

  8. Long-period orbital climate forcing. Cyclostratigraphic studies of Cenozoic continental and marine successions in Europe. Geologica Ultraiectina (297)

    NARCIS (Netherlands)

    Abels, H.A.|info:eu-repo/dai/nl/304848018

    2008-01-01

    Orbital climate forcing is well-known for its strong impact on Earth’s climate as for example the switching from glacial to inter-glacial states in the Late Pleistocene. Typical ‘Milankovitch’ cycles are climatic precession (21.000 years or 21 kyrs), obliquity (41 kyrs), and short and long eccentric

  9. Quantum mechanics in strong time dependent external fields

    Energy Technology Data Exchange (ETDEWEB)

    Pomeau, Y.

    1986-01-01

    In quantum mechanics, time dependent Hamiltonians are most often studied by perturbation methods, the amplitude of the unsteady force being assumed to be small. On two examples (two level system with a large time dependent coupling, and atoms in large external unsteady field). I show that the opposite limit (large time dependent field) can be analyzed in some details too. For a particle in a central potential and submitted to a large periodic external field, one is led to make a Kapitza averaging because the intrinsic frequency tends to zero when the external field diverges. In that way one has to introduce a steady effective potential with singular turning points.

  10. Multi-Model Simulations of Aerosol and Ozone Radiative Forcing Due to Anthropogenic Emission Changes During the Period 1990-2015

    Science.gov (United States)

    Myhre, Gunnar; Aas, Wenche; Ribu, Cherian; Collins, William; Faluvegi, Gregory S.; Flanner, Mark; Forster, Piers; Hodnebrog, Oivind; Klimont, Zbigniew; Lund, Marianne T.

    2017-01-01

    Over the past few decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and air pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990-2015, as simulated by seven global atmospheric composition models. The models broadly reproduce large-scale changes in surface aerosol and ozone based on observations (e.g. 1 to 3 percent per year in aerosols over the USA and Europe). The global mean radiative forcing due to ozone and aerosol changes over the 1990-2015 period increased by 0.17 plus or minus 0.08 watts per square meter, with approximately one-third due to ozone. This increase is more strongly positive than that reported in IPCC AR5 (Intergovernmental Panel on Climate Change Fifth Assessment Report). The main reasons for the increased positive radiative forcing of aerosols over this period are the substantial reduction of global mean SO2 emissions, which is stronger in the new emission inventory compared to that used in the IPCC analysis, and higher black carbon emissions.

  11. Multi-Model Simulations of Aerosol and Ozone Radiative Forcing Due to Anthropogenic Emission Changes During the Period 1990-2015

    Science.gov (United States)

    Myhre, Gunnar; Aas, Wenche; Ribu, Cherian; Collins, William; Faluvegi, Gregory S.; Flanner, Mark; Forster, Piers; Hodnebrog, Oivind; Klimont, Zbigniew; Lund, Marianne T.

    2017-01-01

    Over the past few decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and air pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990-2015, as simulated by seven global atmospheric composition models. The models broadly reproduce large-scale changes in surface aerosol and ozone based on observations (e.g. 1 to 3 percent per year in aerosols over the USA and Europe). The global mean radiative forcing due to ozone and aerosol changes over the 1990-2015 period increased by 0.17 plus or minus 0.08 watts per square meter, with approximately one-third due to ozone. This increase is more strongly positive than that reported in IPCC AR5 (Intergovernmental Panel on Climate Change Fifth Assessment Report). The main reasons for the increased positive radiative forcing of aerosols over this period are the substantial reduction of global mean SO2 emissions, which is stronger in the new emission inventory compared to that used in the IPCC analysis, and higher black carbon emissions.

  12. Multi-model simulations of aerosol and ozone radiative forcing due to anthropogenic emission changes during the period 1990-2015

    Science.gov (United States)

    Myhre, Gunnar; Aas, Wenche; Cherian, Ribu; Collins, William; Faluvegi, Greg; Flanner, Mark; Forster, Piers; Hodnebrog, Øivind; Klimont, Zbigniew; Lund, Marianne T.; Mülmenstädt, Johannes; Myhre, Cathrine Lund; Olivié, Dirk; Prather, Michael; Quaas, Johannes; Samset, Bjørn H.; Schnell, Jordan L.; Schulz, Michael; Shindell, Drew; Skeie, Ragnhild B.; Takemura, Toshihiko; Tsyro, Svetlana

    2017-02-01

    Over the past few decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and air pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990-2015, as simulated by seven global atmospheric composition models. The models broadly reproduce large-scale changes in surface aerosol and ozone based on observations (e.g. -1 to -3 % yr-1 in aerosols over the USA and Europe). The global mean radiative forcing due to ozone and aerosol changes over the 1990-2015 period increased by +0.17 ± 0.08 W m-2, with approximately one-third due to ozone. This increase is more strongly positive than that reported in IPCC AR5. The main reasons for the increased positive radiative forcing of aerosols over this period are the substantial reduction of global mean SO2 emissions, which is stronger in the new emission inventory compared to that used in the IPCC analysis, and higher black carbon emissions.

  13. Comment on "Long-period astronomical forcing of mammal turnover" by van Dam et al., Nature 443:687-691

    CERN Document Server

    Omerbashich, M

    2006-01-01

    Van Dam et al. (2006) claimed 2.4 to 2.5 and 1.0 Myr turnover cycles in a Spanish rodent lineages record. However, the record variance spectrum, which is missing in ibid., shows that the varying reliability and multiple alterations of raw (gapped and unaltered) data by ibid. unnaturally boosted the 2.5 and 1.0 Myr noise cycles to the 99% confidence level, while failing to recognize a third such so called 99% significant noise period, of 0.55 Myr at 5.3 var%. Thus at least one claimed period (of 1.0 Myr) is a simple modulation of a relatively stronger noise cycle (of 0.55 Myr) overlooked by ibid. All so called 99% significant periods reach mere 5 to 6% var levels which can be hardly distinguished from noise: those periods fidelity is at staggering 1 to 2 orders of magnitude below the usual signal to noise separation marker at 12.0. Remarkably, at least ten noise periods got boosted to 95% confidence level, and some five noise periods to near 95% confidence level, as well. Even the zero padding of just 4% of da...

  14. Predicting attenuant and resonant 2-cycles in periodically forced discrete-time two-species population models.

    Science.gov (United States)

    Morena, Matthew A; Franke, John E

    2012-01-01

    Periodic environments may either enhance or suppress a population via resonant or attenuant cycles. We derive signature functions for predicting the responses of two competing populations to 2-periodic oscillations in six model parameters. Two of these parameters provide a non-trivial equilibrium and two provide the carrying capacities of each species in the absence of the other, but the remaining two are arbitrary and could be intrinsic growth rates. Each signature function is the sign of a weighted sum of the relative strengths of the oscillations of the perturbed parameters. Periodic environments are favourable for populations when the signature function is positive and are deleterious if the signature function is negative. We compute the signature functions of four classical, discrete-time two-species populations and determine regions in parameter space which are either favourable or detrimental to the populations. The six-parameter models include the Logistic, Ricker, Beverton-Holt, and Hassell models.

  15. 基于BP神经网络的体外索索力预测及MATLAB实现%Prediction of the external tendons force based on BP neural network and MATLAB

    Institute of Scientific and Technical Information of China (English)

    熊辉霞; 张耀庭; 苗雨

    2011-01-01

    为了进一步研究体外预应力混凝土结构体外索极限应力的确定方法,在分析影响体外预应力混凝土结构体外索极限应力因素的基础上,运用神经网络预测的原理,采用误差反向传播神经网络即BP神经网络对体外索的索力进行了预测.预测结果表明,应用BP神经网络模型能准确的预测体外索的索力.预测结果和试验结果相比误差在10%以内,可以满足实际工程的需要.%In order to determine the maximum stress of the externally prestressed concrete structures, various factors that influence the stress were analyzed, and the theory of BP (Back Propagation) neural network was used to predict the external tendon force. The results show that the BP neural network model can predict the limit of the external tendon force and the error of the results is less than 10% compared to the experiment results, which is good enough to satisfy practical engineering needs.

  16. Critical current measurement with spatial periodic bending imposed by electromagnetic force on a standard test barrel with slots

    NARCIS (Netherlands)

    Nijhuis, A.; Wessel, W.A.J.; Ilyin, Y.; Ouden, den A.; Kate, ten H.H.J.

    2006-01-01

    We have developed and validated a straightforward and fast method to investigate the response of technological superconducting strain sensitive wires (e.g., Nb3Sn) to a spatial periodic bending strain. In the present concept of cabled superconductors for application in nuclear fusion reactors the wi

  17. Analytical and Numerical Studies for Chaotic Dynamics of a Duffing Oscillator with a Parametric Force

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The chaotic dynamics of a Duffing oscillator with a parametric force is investigated. By using the direct perturbation technique, we analytically obtain the general solution of the 1st-order equation. Through the boundedness condition of the general solution we get the famous Melnikov function predicting the onset of chaos. When the parametric and external forces are strong, numerical simulations show that increasing the amplitude of the parametric or external force can lead the system into chaos via period doubling.

  18. Calcium window currents, periodic forcing, and chaos: Understanding single neuron response with a discontinuous one-dimensional map

    Science.gov (United States)

    Laudanski, J.; Sumner, C.; Coombes, S.

    2010-07-01

    Thalamocortical (TC) neurones are known to express the low-voltage activated, inactivating Ca2+ current IT . The triggering of this current underlies the generation of low threshold Ca2+ potentials that may evoke single or bursts of action potentials. Moreover, this current can contribute to an intrinsic slow (dynamics for the gating variables in the model of IT . This model can be analyzed in closed form and is shown to support an unstable set of periodic orbits. Trajectories are repelled from these organizing centers until they reach the threshold for firing. By determining the condition for a grazing bifurcation (at the border between a spiking and nonspiking event) we show how knowledge of the unstable periodic orbits (existence and stability) can be combined with the grazing condition to determine an effective one-dimensional map that captures the essentials of the chaotic behavior. This map is discontinuous and has strong similarities with the universal limit mapping in grazing bifurcations derived in the context of impacting mechanical systems [A. B. Nordmark, Phys. Rev. E 55, 266 (1997)10.1103/PhysRevE.55.266].

  19. Relative contributions of external SST forcing and internal atmospheric variability to July-August heat waves over the Yangtze River valley

    Science.gov (United States)

    Chen, Xiaolong; Zhou, Tianjun

    2017-08-01

    The Yangtze River valley (YRV), located in central-eastern China, has witnessed increased numbers of heat waves in the summer since 1951. Knowing what factors control and affect the interannual variability of heat waves, especially distinguishing the contributions of anomalous sea surface temperature (SST) forcings and those of internal modes of variability, is important to improving heat wave prediction. After evaluating 70 members of the atmospheric model intercomparison project (AMIP) experiments from the 25 models that participated in the coupled model intercomparison project phase 5 (CMIP5), 13 high-skill members (HSMs) are selected to estimate the SST-forced variability. The results show that approximately 2/3 of the total variability of the July-August heat waves in the YRV during 1979-2008 can be attributed to anomalous SST forcings, whereas the other 1/3 are due to internal variability. Within the SST-forced component, one-half of the influence is from the impact of the El Niño-Southern Oscillation (ENSO) and the other half is from non-ENSO related SST forcings, specifically, the SST anomalies in the North Pacific and the North Atlantic. Both the decaying El Niño and developing La Niña accompanied by a warm Indian Ocean and cold central Pacific, respectively, are favorable to hotter summers in the YRV because these patterns strengthen and extend the western North Pacific Subtropical High (WNPSH) westwards, for which the decaying ENSO plays a dominant role. The internal variability shows a circumglobal teleconnection in which Rossby waves propagate southeastwards over the Eurasian Continent and strengthen the WNPSH. Atmospheric model sensitivity experiments confirm that non-ENSO SST forcings can modulate the WNPSH and heat wave variability by projecting their influences onto the internal mode.

  20. The dental specialties related articles published in Medical Journal Armed Forces India from 2000 to 2014 over a 15-year period.

    Science.gov (United States)

    Shamim, Thorakkal

    2015-12-01

    There is a paucity of information about the dental specialties related articles published in the Medical Journal Armed Forces India (MJAFI). This study aimed to audit the dental specialities related articles published in MJAFI from 2000 to 2014 over a 15-year period. Bibliometric analysis of sixty issues of MJAFI from 2000 to 2014 were performed using web-based search. The articles published were analyzed for type of article and topic of individual dental specialities. The articles published were also evaluated to identify whether the study was an Armed Forces Medical Research Committee Project or funded research project or not. Out of the total 118 published articles related to dental specialities, original articles (55) and case reports (49) contribute the major share. The highest number of dental specialities related articles was published in 2009 with 16, followed by 2010 with 13 and 2011 with 11 and the least published year was 2013 with 3 articles. Regarding the relationship with dental specialities, the maximum number of published articles were related to oral medicine and radiology (56) followed by oral and maxillofacial surgery (49), orthodontics (23) and prosthodontics (17). Among the articles published in MJAFI, maxillofacial injuries (11) followed by orthodontic treatment (8) and craniofacial deformities (8) form the major attraction of the contributors. Among the 118 dental speciality articles, there were only 4 Armed Forces Medical Research Committee Project articles and 19 funded research project articles. An equal distribution of articles related to clinical dentistry and nonclinical dentistry is maintained for the MJAFI from 2000 to 2014 over a 15-year period.

  1. The dental specialties related articles published in Medical Journal Armed Forces India from 2000 to 2014 over a 15-year period

    Science.gov (United States)

    Shamim, Thorakkal

    2015-01-01

    There is a paucity of information about the dental specialties related articles published in the Medical Journal Armed Forces India (MJAFI). This study aimed to audit the dental specialities related articles published in MJAFI from 2000 to 2014 over a 15-year period. Bibliometric analysis of sixty issues of MJAFI from 2000 to 2014 were performed using web-based search. The articles published were analyzed for type of article and topic of individual dental specialities. The articles published were also evaluated to identify whether the study was an Armed Forces Medical Research Committee Project or funded research project or not. Out of the total 118 published articles related to dental specialities, original articles (55) and case reports (49) contribute the major share. The highest number of dental specialities related articles was published in 2009 with 16, followed by 2010 with 13 and 2011 with 11 and the least published year was 2013 with 3 articles. Regarding the relationship with dental specialities, the maximum number of published articles were related to oral medicine and radiology (56) followed by oral and maxillofacial surgery (49), orthodontics (23) and prosthodontics (17). Among the articles published in MJAFI, maxillofacial injuries (11) followed by orthodontic treatment (8) and craniofacial deformities (8) form the major attraction of the contributors. Among the 118 dental speciality articles, there were only 4 Armed Forces Medical Research Committee Project articles and 19 funded research project articles. An equal distribution of articles related to clinical dentistry and nonclinical dentistry is maintained for the MJAFI from 2000 to 2014 over a 15-year period. PMID:26858474

  2. Delayed-feedback chimera states: Forced multiclusters and stochastic resonance

    Science.gov (United States)

    Semenov, V.; Zakharova, A.; Maistrenko, Y.; Schöll, E.

    2016-07-01

    A nonlinear oscillator model with negative time-delayed feedback is studied numerically under external deterministic and stochastic forcing. It is found that in the unforced system complex partial synchronization patterns like chimera states as well as salt-and-pepper-like solitary states arise on the route from regular dynamics to spatio-temporal chaos. The control of the dynamics by external periodic forcing is demonstrated by numerical simulations. It is shown that one-cluster and multi-cluster chimeras can be achieved by adjusting the external forcing frequency to appropriate resonance conditions. If a stochastic component is superimposed to the deterministic external forcing, chimera states can be induced in a way similar to stochastic resonance, they appear, therefore, in regimes where they do not exist without noise.

  3. Experimental Study on the Impact of External Geometrical Shape on Free and Forced Convection Time Dependent Average Heat Transfer Coefficient during Cooling Process

    Directory of Open Access Journals (Sweden)

    Sundus Hussein Abd

    2012-01-01

    Full Text Available In this research, an experimental study was conducted to high light the impact of the exterior shape of a cylindrical body on the forced and free convection heat transfer coefficients when the body is hold in the entrance of an air duct. The impact of changing the body location within the air duct and the air speed are also demonstrated. The cylinders were manufactured with circular, triangular and square sections of copper for its high thermal conductivity with appropriate dimensions, while maintaining the surface area of all shapes to be the same. Each cylinder was heated to a certain temperature and put inside the duct at certain locations. The temperature of the cylinder was then monitored. The heat transfer coefficient were then calculated for forced convection for several Reynolds number (4555-18222.The study covered free convection impact for values of Rayleigh number ranging between (1069-3321. Imperical relationships were obtained for all cases of forced and free convection and compared with equations of circular cylindrical shapes found in literature. These imperical equations were found to be in good comparison with that of other sources.

  4. Families of Fokker-Planck equations and the associated entropic form for a distinct steady-state probability distribution with a known external force field.

    Science.gov (United States)

    Asgarani, Somayeh

    2015-02-01

    A method of finding entropic form for a given stationary probability distribution and specified potential field is discussed, using the steady-state Fokker-Planck equation. As examples, starting with the Boltzmann and Tsallis distribution and knowing the force field, we obtain the Boltzmann-Gibbs and Tsallis entropies. Also, the associated entropy for the gamma probability distribution is found, which seems to be in the form of the gamma function. Moreover, the related Fokker-Planck equations are given for the Boltzmann, Tsallis, and gamma probability distributions.

  5. Impact of volcanism on the evolution of Lake Van (eastern Anatolia) III: Periodic (Nemrut) vs. episodic (Süphan) explosive eruptions and climate forcing reflected in a tephra gap between ca. 14 ka and ca. 30 ka

    Science.gov (United States)

    Schmincke, Hans-Ulrich; Sumita, Mari

    2014-09-01

    Fifteen Lateglacial to Holocene rhyolitic, dominantly primary tephra layers piston-cored and drilled (ICDP Paleovan drilling project) in western Lake Van (eastern Anatolia, Turkey) were precisely correlated to either of the two adjacent and active large volcanoes Nemrut and Süphan based on shard textures, mineralogy and mineral and glass compositions. The young peralkaline (comenditic to pantelleritic) primary rhyolitic Nemrut tephras are characterized by anorthoclase, hedenbergitic to augitic clinopyroxene, fayalitic olivine, minor quartz, and rare accessory chevkinite and zircon. Phenocrysts in subalkaline primary rhyolitic Süphan tephras are chiefly oligoclase-labradorite, with minor K-rich sanidine in some, biotite, amphibole, hypersthene, rare augitic clinopyroxene, relatively common allanite and rare zircon. Two contrasting explosive eruptive modes are distinguished from each other: episodic (Süphan) and periodic (Nemrut). The Lateglacial Süphan tephra swarm covers a short time interval of ca. 338 years between ca. 13,078 vy BP and 12,740 vy BP, eruptions having occurred statistically every ca. 42 years with especially short intervals between V-11 (reworked) and V-14. Causes for the strongly episodic Süphan explosive behavior might include seismic triggering of a volcano-magma system unable to erupt explosively without the benefit of external triggering, as reflected in pervasive faulting preceding the Süphan tephra swarm. Seismic triggering may have caused the rise of more mafic ("trachyandesitic") parent magma, heating near-surface pockets of highly evolved magma - that might have formed silicic domes during this stage of volcano evolution - resulting in ascent and finally explosive fragmentation of magma essentially by external factors, probably significantly enhanced by magma-water/ice interaction. Explosive eruptions of the Nemrut volcano system, interpreted to be underlain by a large fractionating magma reservoir, follow a more periodic mode of (a

  6. Evaluation of the occupational exposure to external sources of ionizing radiation in Cuba in the period 2001-2005; Evaluacion de la exposicion ocupacional a fuentes externas de radiacion ionizante en Cuba en el periodo 2001-2005

    Energy Technology Data Exchange (ETDEWEB)

    Molina P, D.; Martinez H, E.; Castro S, A. [Laboratorio de Dosimetria Externa, CPHR, A.P. 6195, C.P. 10600, La Habana (Cuba)]. e-mail: daniel@cphr.edu.cu

    2006-07-01

    The single radiological surveillance of the occupational exposure to external radiation sources in Cuba it is carried out by the Radiation Protection and Hygiene Center (CPHR). The data corresponding to the external exposure are presented. The service it covers to all the occupationally exposed workers (TOEs) of the country that work fundamentally the radiodiagnostic practices, nuclear medicine, radiotherapy and research. The purpose of this work is to carry out an analysis of the occupational exposures of the TOE of the country starting of the results registered by the service of single radiological surveillance in the period 2001 to 2005, keeping in mind the indicators used by the UNSCEAR. The annual average effective dose (E) for each practice is shown. The obtained results showed that the values of annual average effective dose (E) its are bigger for the radiodiagnostic practices, radiotherapy and nuclear medicine. In a general way, all the E values are inferior to 2.00 mSv. The number of TOEs that overcame the 20 mSv established as annual dose limit, it went inferior to 1% of the controlled total universe. (Author)

  7. Internal and external North Atlantic Sector variability in the Kiel climate model

    Energy Technology Data Exchange (ETDEWEB)

    Latif, Mojib; Park, Wonsun; Ding, Hui; Keenlyside, Noel S. [Leibniz-Inst. fuer Meereswissenschaften, Kiel (Germany)

    2009-08-15

    The internal and external North Atlantic Sector variability is investigated by means of a multimillennial control run and forced experiments with the Kiel Climate Model (KCM). The internal variability is studied by analyzing the control run. The externally forced variability is investigated in a run with periodic millennial solar forcing and in greenhouse warming experiments with enhanced carbon dioxide concentrations. The surface air temperature (SAT) averaged over the Northern Hemisphere simulated in the control run displays enhanced variability relative to the red background at decadal, centennial, and millennial timescales. Special emphasis is given to the variability of the Meridional Overturning Circulation (MOC). The MOC plays an important role in the generation of internal climate modes. Furthermore, the MOC provides a strong negative feedback on the Northern Hemisphere SAT in both the solar and greenhouse warming experiments, thereby moderating the direct effects of the external forcing in the North Atlantic. The implications of the results for decadal predictability are discussed. (orig.)

  8. Application of antimicrobial agents during perioperative period of abdominal external hernia%腹外疝手术围手术期抗菌药物应用分析

    Institute of Scientific and Technical Information of China (English)

    付琴

    2012-01-01

    目的 了解腹外疝手术围手术期抗菌药物使用特点,探讨其存在的主要问题,为规范基层综合医院抗菌药物的应用提供依据,并制定抗菌药物使用的干预措施.方法 对2010年1-6月符合Ⅰ类切口的腹外疝手术的归档病历,进行回顾性调查分析.结果 腹外疝手术围手术期抗菌药物使用率为100.00%,抗菌药物联合应用率为25.35%,用药疗程平均(6.52±1.43)d;医院腹外疝围手术期抗菌药物应用方面尚存在一些用药指征把握不严、给药时机不佳、用药品种不当、给药疗程过长及盲目联合用药等问题.结论 必须加强抗菌药物使用管理,规范基层综合医院腹外疝手术围手术期抗菌药物的应用,才能遏制细菌耐药性快速增长的不良趋势.%OBJECTIVE To evaluate the application of antimicrobial agents during perioperative period of abdominal external hernia and investigate the existing problems so as to provide evidence for standardizing the antibiotic use in grass-root hospital and institute intervention measures.METHODS A retrospective analysis was conducted for the filed medical cases complying with the abdominal external hernia for class I incision from Jan.to Jun.2010.RESULTS Application rate of antibiotics was 100.00% during perioperative period of abdominal external hernia.The rate of combined use of antimicrobial agents was 25.35%; the mean medication course was (6.52 d ±1.43) d; results from present study indicated several existing problems.including not following drug indications strictly, timing errors in medication administration, improper medicationt excessive medication duration, blind combination therapy and so on.CONCLUSION The use of antimicrobial agents should be strengthened, the application of antibiotics during perioperative period of abdominal external hernia should be standardized in the grass-root general hospital so as to curb the rapid growth of bacterial resistance

  9. Current Reversal Due to Coupling Between Asymmetrical Driving Force and Ratchet Potential

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potential are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal. The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals.

  10. Biogeochemistry and ecosystems of continental margins in the western North Pacific Ocean and their interactions and responses to external forcing - an overview and synthesis

    Science.gov (United States)

    Liu, K.-K.; Kang, C.-K.; Kobari, T.; Liu, H.; Rabouille, C.; Fennel, K.

    2014-12-01

    In this special issue we examine the biogeochemical conditions and marine ecosystems in the major marginal seas of the western North Pacific Ocean, namely, the East China Sea, the Japan/East Sea to its north and the South China Sea to its south. They are all subject to strong climate forcing as well as anthropogenic impacts. On the one hand, continental margins in this region are bordered by the world's most densely populated coastal communities and receive tremendous amount of land-derived materials. On the other hand, the Kuroshio, the strong western boundary current of the North Pacific Ocean, which is modulated by climate oscillation, exerts strong influences over all three marginal seas. Because these continental margins sustain arguably some of the most productive marine ecosystems in the world, changes in these stressed ecosystems may threaten the livelihood of a large population of humans. This special issue reports the latest observations of the biogeochemical conditions and ecosystem functions in the three marginal seas. The studies exemplify the many faceted ecosystem functions and biogeochemical expressions, but they reveal only a few long-term trends mainly due to lack of sufficiently long records of well-designed observations. It is critical to develop and sustain time series observations in order to detect biogeochemical changes and ecosystem responses in continental margins and to attribute the causes for better management of the environment and resources in these marginal seas.

  11. On the Nonlinear Response of Lower Stratospheric Ozone to External Forces-The Inclusion of BrOx and Radiation Processes

    Institute of Scientific and Technical Information of China (English)

    WANG Geli; YAN Jianjun; YANG Peicai

    2012-01-01

    In this paper the bromine family and radiative effects are considered in an updated box model under the framework of ozone temperature feedback,in order to further analyze the possible behavior of atmospheric ozone in the lower mid-latitude stratosphere.Results show that this updated photochemical system can present several different solutions,within a certain domain of parameters,with fixed-point and periodic states appearing in turn.The temperature feedback effect introduced in this box model has not changed the topology of the ozone system.This result presents nonlinear characteristics of the ozone system,and possible trends in the stratospheric atmosphere between complex chemistry and radiation processes.

  12. On population resilience to external perturbations

    CERN Document Server

    Roques, Lionel

    2010-01-01

    We study a spatially explicit harvesting model in periodic or bounded environments. The model is governed by a parabolic equation with a spatially dependent nonlinearity of Kolmogorov--Petrovsky--Piskunov type, and a negative external forcing term $-\\delta$. Using sub- and supersolution methods and the characterization of the first eigenvalue of some linear elliptic operators, we obtain existence and nonexistence results as well as results on the number of stationary solutions. We also characterize the asymptotic behavior of the evolution equation as a function of the forcing term amplitude. In particular, we define two critical values $\\delta^*$ and $\\delta_2$ such that, if $\\delta$ is smaller than $\\delta^*$, the population density converges to a "significant" state, which is everywhere above a certain small threshold, whereas if $\\delta$ is larger than $\\delta_2$, the population density converges to a "remnant" state, everywhere below this small threshold. Our results are shown to be useful for studying th...

  13. Defensive externality and blame projection following failure.

    Science.gov (United States)

    Hochreich, D J

    1975-09-01

    This study focuses upon the relationship between internal-external control and defensive blame projection. Trust was used as a moderator variable for making differential predictions concerning the behavior of two subgroups of externals: defensive externals, whose externality is presumed to reflect primarily a verbal technique of defense, and congruent externals, whose externality reflects a more genuine belief that most outcomes are determined by forces beyond their personal control. As predicted, defensive externals showed a stronger tendency than did congruent externals and internals to resort to blame projection following failure at an achievement task. There were no group differences in attribution following task success. Defensive externals were found to be more responsive to negative feedback than were congruent externals.

  14. Effect of feed consumption levels on growth performance and carcass composition during the force-feeding period in foie gras production of male Mule ducks.

    Science.gov (United States)

    Wen, Z G; Jiang, Y; Tang, J; Xie, M; Yang, P L; Hou, S S

    2016-09-01

    In order to avoid excess feed consumption during the force-feeding period in foie gras production, a dose-response experiment with seven feed consumption levels (450, 540, 630, 720, 810, 900, 990 g/day per bird) was conducted to evaluate the effects of feed consumption levels on growth performance and carcass composition of male Mule ducks from 91 to 102 days of age. One-day-old Mule ducklings (sterile and artificial hybrid of male Albatre Muscovy duck and female Pekin duck were fed a two-phase commercial diets for ad libitum intake from hatching to 91 days of age, followed by graded feeding levels of a corn diet by force-feeding from 91 to 102 days of age. Fifty-six 91-day-old male Mule ducks with similar BW were randomly assigned to seven treatments, with eight birds per treatment. Birds were housed in individual pens. At 102 days of age, final BW was measured and BW gain and feed conversion ratio of ducks from each treatment were calculated from day 91 to 102, and then all ducks were slaughtered to evaluate the yields of skin with subcutaneous fat, abdominal fat, breast meat (including pectoralis major and pectoralis minor), leg meat (including thigh and drum stick), and liver. Significant differences in BW gain, total liver weight and liver relative weight were observed among the treatments (P<0.001). According to the broken-line regression analysis, the optimal feed consumption levels of male Mule ducks from 91 to 102 days of age for maximum BW gain, total liver weight and liver relative weight were 217, 227 and 216 g feed/kg BW0.75·per day, respectively.

  15. 基于外部性与经营期电价的风电经济性研究%Research on Wind Power Economy Based on Operation Period Price and Externality

    Institute of Scientific and Technical Information of China (English)

    岳建坤; 张粒子

    2012-01-01

    风电的外部影响主体主要包括环境、电网和用户。将外部成本和收益内部化是研究风电经济性的前提条件。考虑了风电的减排效益及对电网备用的影响,基于经营期电价,测算其在预期收益下合理的上网电价,并提出经济发电利用小时数概念,为研究风电投资可行性提供参考。结果表明,在综合考虑内外部成本和收益的前提下,在目前技术条件下,风电合理的上网电价与我国现行风电标杆电价一致,仍高于常规能源电价。结果证明了方法的有效性。%The main subjects that wind power has external influences on are environment,power system and users. The internalization of external costs and benefits is a prerequisite for research of wind power economy. The paper calculated reasonable generation price of wind power in the ex pected rate of return based on operation period price with consideration of its emission reduction benefits and its impact on the grid's reserve capaci ty,then put forward the concept of economic annual generating hours,providing a reference for the investment feasibility of wind power project. The results show that under the current conditions, taking external costs and benefits into account, reasonable generation price of wind power is consist ent with China's current wind power benchmark price, still higher than traditional energy generation price. The results prove the effectiveness of the method.

  16. Empirical Evaluation On External Debt Of Malaysia

    OpenAIRE

    Nor’Aznin Abu Bakar; Sallahuddin Hassan

    2011-01-01

    This study analyzes the effects of external debts on economic growth in Malaysia. The analysis is conducted both at aggregate and disaggregate levels. The empirical results are based on VAR estimates using GDP, external debts, capital accumulation, labor force and human capital. Estimation results at the aggregate level indicate that total external debts affect economic growth positively. In particular, one percentage point increase in total external debts generates 1.29 percentage point of e...

  17. Cascade of period doublings of tori

    Science.gov (United States)

    Arneodo, A.; Coullet, P. H.; Spiegel, E. A.

    1983-02-01

    A three-dimensional map is proposed to model the effects of periodic forcing on a system displaying a transition to chaos through a cascade of period-doubling bifurcations. The study outlined here raises the problem of the existence and bifurcation of invariant tori. A principal feature of the simulations of both the differential equations and the discrete dynamical systems is that it is possible to disrupt period-doubling sequences (and inverse sequences as well) by periodic external forcing. Even though the way in which this abortion works is not understood, the mechanism is thought to be associated with the destruction of tori (Aronson et al., 1982) when the system is on the verge of bifurcation. The simulations therefore suggest that in moving farther along the cascade, the tori become more fragile. It is suspected that for arbitrarily weak driving, the cascade will eventually be disrupted after the cascade has proceeded through a sufficient number of steps.

  18. [Bilateral eye injuries by external transversal force].

    Science.gov (United States)

    Geidel, K; Schob, S; Unterlauft, J D; Wiedemann, P; Meier, P

    2016-12-14

    A 49-year-old female victim of violent crime with an acute bilateral loss of vision was referred to our hospital. The ophthalmological evaluation showed complete subconjunctival hemorrhage of both eyes, bilateral hemophthalmos and hypotonia of the left eye. These raised the suspicion of an occult scleral rupture. We immediately performed exploratory surgery and found a perforating scleral lesion of the left eye and a penetrating scleral lesion of the right eye. Furthermore, a small, cruciform wound was detected on the left temple. In cooperation with the department of radiology, the extraordinary injury pattern was reconstructed: a horizontal stab wound with perforation of the left eye and penetration of the right eye caused by a screwdriver. Visual rehabilitation necessitated further surgical interventions. Besides the intraoperative approach, immediate primary wound management within 100 h of trauma plays a pivotal role for long-term outcome.

  19. External Otitis (Swimmer's Ear)

    Science.gov (United States)

    ... to Pneumococcal Vaccine Additional Content Medical News External Otitis (Swimmer's Ear) By Bradley W. Kesser, MD, Associate ... the Outer Ear Ear Blockages Ear Tumors External Otitis (Swimmer's Ear) Malignant External Otitis Perichondritis External otitis ...

  20. International labor migration and external debt.

    Science.gov (United States)

    Bustamante, J A

    1987-01-01

    The prevailing Mexican and US definitions of undocumented migration are poles apart. The US views it as a criminal problem. Mexicans view the undocumented migrants as actors in an economic game in which the rules are extremely disadvantageous to these migrants. Migrants themselves and their communities view the undocumented as a positive element. It is necessary to move toward a bilateral focus and bilateral negotiation on the issue of migratory workers. This proposal derives from several assumptions: 1) the external debt is a bilateral or multilateral issue, 2) it is important to avoid forcing debtor countries to choose between stimulating economic growth or making payment on their foreign debt, 3) prevailing public opinion in the US favors halting undocumented migration, 4) the US views the migration of undocumented Mexicans as the result of forces endogenous to Mexico and exogenous to the US, 5) the US views both Mexico's ability to make payment on its external debt and to halt emigration as tied to the Mexican government's ability or inability to reconcile political stability with scarce monetary resources, and 6) political instability in Mexico could augment emigration to the US and undermine Mexico's ability to address its foreign debt. The following proposal suggests means to link negotiation on the external debt to that of undocumented migration: 1) The Mexican government could reach an accord with the US to channel a portion of the actual interest on the external debt as a fund to be invested in Mexico to construct a system of labor intensive agroindustrial productive units designed to attract former or potential migratory workers; 2) the total amount of these funds would be deducted from interest payments on the principal of the actual external debt and redefined as an ad hoc loan to Mexico to finance these production units; 3) part of the production from these units would be incorporated into ongoing US food relief and food assistance programs; 4) the

  1. Bifurcation of Periodic Orbits and Chaos in Duffing Equation

    Institute of Scientific and Technical Information of China (English)

    Mei-xiang Cai; Jian-ping Yang

    2006-01-01

    Duffing equation with fifth nonlinear-restoring force, one external forcing and a phase shift is investigated. The conditions of existences for primary resonance, second-order, third-order subharmonics, morder subharmonics and chaos are given by using second-averaging method, Melnikov methods and bifurcation theory. Numerical simulations including bifurcation diagrams, bifurcation surfaces, phase portraits, not only show the consistence with the theoretical analysis, but also exhibit the new dynamical behaviors. We show the onset of chaos, chaos suddenly disappearing to period orbit, one-band and double-band chaos, period-doubling bifurcations from period 1, 2, and 3 orbits, period-windows (period-2, 3 and 5) in chaotic regions.

  2. The impact of air pollutant and methane emission controls on tropospheric ozone and radiative forcing: CTM calculations for the period 1990–2030

    Directory of Open Access Journals (Sweden)

    F. Raes

    2004-12-01

    Full Text Available To explore the relationship between tropospheric ozone and radiative forcing with changing emissions, we compiled two sets of global scenarios for the emissions of the ozone precursors methane (CH4, carbon monoxide (CO, non-methane volatile organic compounds (NMVOC and nitrogen oxides (NOx up to the year 2030 and implemented them in two global Chemistry Transport Models. The "Current Legislation" (CLE scenario reflects the current perspectives of individual countries on future economic development and takes the anticipated effects of presently decided emission control legislation in the individual countries into account. In addition, we developed a "Maximum technically Feasible Reduction" (MFR scenario that outlines the scope for emission reductions offered by full implementation of the presently available emission control technologies, while maintaining the projected levels of anthropogenic activities. Whereas the resulting projections of methane emissions lie within the range suggested by other greenhouse gas projections, the recent pollution control legislation of many Asian countries, requiring introduction of catalytic converters for vehicles, leads to significantly lower growth in emissions of the air pollutants NOx, NMVOC and CO than was suggested by the widely used IPCC (Intergovernmental Panel on Climate Change SRES (Special Report on Emission Scenarios scenarios (Nakicenovic et al., 2000. With the TM3 and STOCHEM models we performed several long-term integrations (1990–2030 to assess global, hemispheric and regional changes in CH4, CO, hydroxyl radicals, ozone and the radiative climate forcings resulting from these two emission scenarios. Both models reproduce realistically the observed trends in background ozone, CO, and CH4 concentrations from 1990 to 2002. For the "current legislation" case, both models indicate an increase of the annual average ozone levels in the Northern hemisphere by 5 ppbv, and up to 15 ppbv over the Indian

  3. Stepwise drying of Lake Turkana at the end of the African Humid Period: a forced regression modulated by solar activity variations?

    Science.gov (United States)

    Nutz, Alexis; Schuster, Mathieu

    2016-12-01

    Although the timing of the termination of the African Humid Period (AHP) is now relatively well established, the modes and controlling factors of this drying are still debated. Here, through a geomorphological approach, we characterize the regression of Lake Turkana at the end of the AHP. We show that lake level fall during this period was not continuous but rather stepwise and consisted of five episodes of rapid lake level fall separated by episodes marked by slower rates of lake level fall. Whereas the overall regressive trend reflects a decrease in regional precipitations linked to the gradual reduction in Northern Hemisphere summer insolation, itself controlled by orbital precession, we focus discussion on the origin of the five periods of accelerated lake level fall. We propose that these periods are due to temporary reductions in rainfall across the Lake Turkana area associated with repeated westward displacement of the Congo Air Boundary (CAB) during solar activity minima.

  4. Resonance-enhanced optical forces between coupled photonic crystal slabs.

    Science.gov (United States)

    Liu, Victor; Povinelli, Michelle; Fan, Shanhui

    2009-11-23

    The behaviors of lateral and normal optical forces between coupled photonic crystal slabs are analyzed. We show that the optical force is periodic with displacement, resulting in stable and unstable equilibrium positions. Moreover, the forces are strongly enhanced by guided resonances of the coupled slabs. Such enhancement is particularly prominent near dark states of the system, and the enhancement effect is strongly dependent on the types of guided resonances involved. These structures lead to enhancement of light-induced pressure over larger areas, in a configuration that is directly accessible to externally incident, free-space optical beams.

  5. The impact of air pollutant and methane emission controls on tropospheric ozone and radiative forcing: CTM calculations for the period 1990-2030

    Directory of Open Access Journals (Sweden)

    F. Dentener

    2005-01-01

    Full Text Available To explore the relationship between tropospheric ozone and radiative forcing with changing emissions, we compiled two sets of global scenarios for the emissions of the ozone precursors methane (CH4, carbon monoxide (CO, non-methane volatile organic compounds (NMVOC and nitrogen oxides (NOx up to the year 2030 and implemented them in two global Chemistry Transport Models. The 'Current Legislation' (CLE scenario reflects the current perspectives of individual countries on future economic development and takes the anticipated effects of presently decided emission control legislation in the individual countries into account. In addition, we developed a 'Maximum technically Feasible Reduction' (MFR scenario that outlines the scope for emission reductions offered by full implementation of the presently available emission control technologies, while maintaining the projected levels of anthropogenic activities. Whereas the resulting projections of methane emissions lie within the range suggested by other greenhouse gas projections, the recent pollution control legislation of many Asian countries, requiring introduction of catalytic converters for vehicles, leads to significantly lower growth in emissions of the air pollutants NOx, NMVOC and CO than was suggested by the widely used and more pessimistic IPCC (Intergovernmental Panel on Climate Change SRES (Special Report on Emission Scenarios scenarios (Nakicenovic et al., 2000, which made Business-as-Usual assumptions regarding emission control technology. With the TM3 and STOCHEM models we performed several long-term integrations (1990-2030 to assess global, hemispheric and regional changes in CH4, CO, hydroxyl radicals, ozone and the radiative climate forcings resulting from these two emission scenarios. Both models reproduce broadly the observed trends in CO, and CH4 concentrations from 1990 to 2002. For the 'current legislation' case, both models indicate an increase of the annual average ozone

  6. Containment atmosphere response to external sprays

    Energy Technology Data Exchange (ETDEWEB)

    Green, J.; Almenas, K. [Univ. of Maryland, College Park, MD (United States)

    1995-09-01

    The application of external sprays to a containment steel shell can be an effective energy removal method and has been proposed in the passive AP-600 design. Reduction of the steel shell temperature in contact with the containment atmosphere enhances both heat and mass transfer driving forces. Large scale experimental data in this area is scarce, therefore the measurements obtained from the E series tests conducted at the German HDR facility deserve special attention. These long term tests simulated various severe accident conditions, including external spraying of the hemispherical steel shell. This investigation focuses upon the integral response of the HDR containment atmosphere during spray periods and upon methods by which lumped parameter system codes, like CONTAIN, model the underlying condensation phenomena. Increases in spray water flowrates above a minimum value were ineffective at improving containment pressure reduction since the limiting resistance for energy transfer lies in the noncondensable-vapor boundary layer at the inner condensing surface. The spray created an unstable condition by cooling the upper layers of a heated atmosphere and thus inducing global natural circulation flows in the facility and subsequently, abrupt changes in lighter-than-air noncondensable (J{sub 2}/He) concentrations. Modeling results using the CONTAIN code are outlined and code limitations are delineated.

  7. Synchronization of a forced self-sustained Duffing oscillator

    CERN Document Server

    Zanette, Damián H

    2014-01-01

    We study the dynamics of a mechanical oscillator with linear and cubic forces -the Duffing oscillator- subject to a feedback mechanism that allows the system to sustain autonomous periodic motion with well-defined amplitude and frequency. First, we characterize the autonomous motion for both hardening and softening nonlinearities. Then, we analyze the oscillator's synchronizability by an external periodic force. We find a regime where, unexpectedly, the frequency range where synchronized motion is possible becomes wider as the amplitude of oscillations grows. This effect of nonlinearities may find application in technological uses of mechanical Duffing oscillators -for instance, in the design of time-keeping devices at the microscale- which we briefly review.

  8. The External Degree.

    Science.gov (United States)

    Houle, Cyril O.

    This book examines the external degree in relation to the extremes of attitudes, myths, and data. Emphasis is placed on the emergence of the American external degree, foreign external-degree programs, the purpose of the external degree, the current scene, institutional issues, and problems of general policy. (MJM)

  9. Response to various periods of mechanical stimuli in Physarum plasmodium

    Science.gov (United States)

    Umedachi, Takuya; Ito, Kentaro; Kobayashi, Ryo; Ishiguro, Akio; Nakagaki, Toshiyuki

    2017-06-01

    Response to mechanical stimuli is a fundamental and critical ability for living cells to survive in hazardous conditions or to form adaptive and functional structures against force(s) from the environment. Although this ability has been extensively studied by molecular biology strategies, it is also important to investigate the ability from the viewpoint of biological rhythm phenomena so as to reveal the mechanisms that underlie these phenomena. Here, we use the plasmodium of the true slime mold Physarum polycephalum as the experimental system for investigating this ability. The plasmodium was repetitively stretched for various periods during which its locomotion speed was observed. Since the plasmodium has inherent oscillation cycles of protoplasmic streaming and thickness variation, how the plasmodium responds to various periods of external stretching stimuli can shed light on the other biological rhythm phenomena. The experimental results show that the plasmodium exhibits response to periodic mechanical stimulation and changes its locomotion speed depending on the period of the stretching stimuli.

  10. Combination of external loads

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, S.; Tarp Johansen, N.J.; Joergensen, H. [Forskningscenter Risoe, Roskilde (Denmark); Gravesen, H.; Soerensen, S.L. [Carl Bro, Glostrup (Denmark); Pedersen, J. [Elsam Engineering, Fredericia (Denmark); Zorn, R.; Hvidberg Knudsen, M. [DHI Water and Environment, Hoersholm (Denmark); Voelund, P. [Energi E2, Koebenhavn (Denmark)

    2003-09-01

    The project onbectives have been: To improve and consequently opimise the basis for design of offshore wind turbines. This is done through 1) mapping the wind, wave ice and current as well as correlations of these, and 2) by clarifyring how these external conditions transform into loads. A comprehensive effort has been made to get a thorough understanding of the uncertainties that govern the reliability of wind turbines with respect to wind and wave loading. One of the conclusions is that the reliability of wind turbines is generally lower, than the average reliability of building structures that are subject not only to environmental loads, which are very uncertain, but also imposed loads and self weight, which are less uncertain than the environmental loads. The implication is that, at the moment lower load partial safety factors for onshore wind turbines cannot be recommended. For the combination of wind and wave design loads the problem is twofold: 1). A very conservative design will be generated by simply adding the individual wind and wave design loads disregarding the independence of the short-term fluctuations of wind and wave loads. 2). Characteristic values and partial safety factors for wind and wave loads are not defined similarly. This implies that the reliability levels of turbine support structures subject to purely aerodynamic loads and subject to purely hydrodynamic loads are not identical. For the problem of combining aerodynamic design loads and hydrodynamic design loads two results have been obtained in the project: 1). By simple means a site specific wave load safety factor rendering the same safety level for hydrodynamic loads as for aerodynamic loads is derived, and next, by direct square summation of extreme fluctuations, the wind and wave load safety factors are weighted. 2). Under the assumptions that a deep water site is considered and that the wave loading is a fifty-fifty mix of drag and inertia the same wind and wave load safety factor

  11. The organizational set as the replenishment of the labour force for industrial enterprises of Donbass in the post-war period

    Directory of Open Access Journals (Sweden)

    N. F. Shypik

    2014-12-01

    Serious problems that emerged in the organizational set were – failure to plan, high turnover of recruited through poor living conditions, poor work organization and roughness from direct management. In 40-es of the twentieth century, the organizational set only worked to replenish the labor force of the region. In the early 50-es, with the gradual saturation of the workforce of the industrial objects were created Stalin and Voroshilovgrad oblast recruitment office, which began to perform tasks on the organizational set for enterprises of the Urals and the Far East. Some hope in their implementation depended on the category of the amnestied people. At the same time there was a shift away from labour law of wartime.

  12. Regulating multiple externalities

    DEFF Research Database (Denmark)

    Waldo, Staffan; Jensen, Frank; Nielsen, Max

    2016-01-01

    Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory instrume......Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory...

  13. 内外取热器影响装置长周期运行的因素及对策%Effects of Internal and External Heat Exchanger Device for Long Period Operation Factors and Countermeasures

    Institute of Scientific and Technical Information of China (English)

    艾克利; 张玉宝; 康钰海; 李宏; 郭保宏; 安德会

    2012-01-01

    External heat exchanger main failure form of tube bundle leakage and finned tube distortion,the main reason is the erosion wear,corrosion,welding defects and their structure is not reasonable.The paper on the 60 Mt / a device of heavy oil catalytic cracking heat exchanger in the production of the problems in the running process,influence factors,management and technical defects of the effects obtained after analysis,in order to prolong the using life of external heat exchanger,energy saving,promoting device for diesel and jet operation purpose.%内外取热器失效的主要表现形式为管束泄漏和翅片管变形,其主要原因是冲蚀磨损、腐蚀穿孔、焊接缺陷以及结构不合理等。文章就60 Mt/a重油催化裂化装置取热器在生产运行过程中出现的问题、影响因素、管理缺陷以及技改后所取得的成效加以分析,以期延长外取热器使用寿命,节能降耗,促进装置安稳长满优运行的目的。

  14. Significance of power average of sinusoidal and non-sinusoidal periodic excitations in nonlinear non-autonomous system

    Indian Academy of Sciences (India)

    VENKATESH P R; VENKATESAN A

    2016-07-01

    Additional sinusoidal and different non-sinusoidal periodic perturbations applied to the periodically forced nonlinear oscillators decide the maintainance or inhibitance of chaos. It is observed that the weak amplitude of the sinusoidal force without phase is sufficient to inhibit chaos rather than the other non-sinusoidal forces and sinusoidal force with phase. Apart from sinusoidal force without phase, i.e., from various non-sinusoidal forces and sinusoidal force with phase, square force seems to be an effective weak perturbation to suppress chaos. The effectiveness of weak perturbation for suppressing chaos is understood with the total power average of the external forces applied to the system. In any chaotic system, the total power average of the external forces isconstant and is different for different nonlinear systems. This total power average decides the nature of the force to suppress chaos in the sense of weak perturbation. This has been a universal phenomenon for all the chaoticnon-autonomous systems. The results are confirmed by Melnikov method and numerical analysis. With the help of the total power average technique, one can say whether the chaos in that nonlinear system is to be supppressed or not.

  15. ExternE National Implementation Finland

    Energy Technology Data Exchange (ETDEWEB)

    Pingoud, K.; Maelkki, H.; Wihersaari, M.; Pirilae, P. [VTT Energy, Espoo (Finland); Hongisto, M. [Imatran Voima Oy, Vantaa (Finland); Siitonen, S. [Ekono Energy Ltd, Espoo (Finland); Johansson, M. [Finnish Environment Institute, Helsinki (Finland)

    1999-07-01

    ExternE National Implementation is a continuation of the ExternE Project, funded in part by the European Commission's Joule III Programme. This study is the result of the ExternE National Implementation Project for Finland. Three fuel cycles were selected for the Finnish study: coal, peat and wood-derived biomass, which together are responsible for about 40% of total electricity generation in Finland and about 75% of the non-nuclear fuel based generation. The estimated external costs or damages were dominated by the global warming (GW) impacts in the coal and peat fuel cycles, but knowledge of the true GW impacts is still uncertain. From among other impacts that were valued in monetary terms the human health damages due to airborne emissions dominated in all the three fuel cycles. Monetary valuation for ecosystem impacts is not possible using the ExternE methodology at present. The Meri-Pori power station representing the coal fuel cycle is one of the world's cleanest and most efficient coal-fired power plants with a condensing turbine. The coal is imported mainly from Poland. The estimated health damages were about 4 mECU/kWh, crop damages an order of magnitude lower and damages caused to building materials two orders of magnitude lower. The power stations of the peat and biomass fuel cycles are of CHP type, generating electricity and heat for the district heating systems of two cities. Their fuels are of domestic origin. The estimated health damages allocated to electricity generation were about 5 and 6 mECU/kWh, respectively. The estimates were case-specific and thus an generalisation of the results to the whole electricity generation in Finland is unrealistic. Despite the uncertainties and limitations of the methodology, it is a promising tool in the comparison of similar kinds of fuel cycles, new power plants and pollution abatement technologies and different plant locations with each other. (orig.)

  16. Thermodynamic cost of external control

    Science.gov (United States)

    Barato, Andre C.; Seifert, Udo

    2017-07-01

    Artificial molecular machines are often driven by the periodic variation of an external parameter. This external control exerts work on the system of which a part can be extracted as output if the system runs against an applied load. Usually, the thermodynamic cost of the process that generates the external control is ignored. Here, we derive a refined second law for such small machines that include this cost, which is, for example, generated by free energy consumption of a chemical reaction that modifies the energy landscape for such a machine. In the limit of irreversible control, this refined second law becomes the standard one. Beyond this ideal limiting case, our analysis shows that due to a new entropic term unexpected regimes can occur: the control work can be smaller than the extracted work and the work required to generate the control can be smaller than this control work. Our general inequalities are illustrated by a paradigmatic three-state system.

  17. External fixators in haemophilia.

    Science.gov (United States)

    Lee, V; Srivastava, A; PalaniKumar, C; Daniel, A J; Mathews, V; Babu, N; Chandy, M; Sundararaj, G D

    2004-01-01

    External fixators (EF) are not commonly used for patients with haemophilia. We describe the use of EF (Ilizarov, AO- uni- and bi-planar fixators and Charnley clamp) in nine patients (mean age: 19.2 years; range: 9-37) with haemophilia for the following indications - arthrodesis of infected joints, treatment of open fractures and osteoclasis. EF required an average of nine skin punctures [range: 4-17 were maintained for a period of 15 weeks (range: 8-29.5), without regular factor replacement, till bone healing was adequate and were removed with a single dose of factor infusion]. The mean preoperative factor level achieved was 85% (range: 64-102%). Much lower levels were subsequently maintained till wound healing. The average total factor consumption was 430 IU kg(-1) (range: 240-870), administered over a period of 17 days (range: 9-44). There were no major complications related to EF except in a patient who developed inhibitors. In conclusion, EF can be used safely in haemophilic patients who do not have inhibitors and does not require prolonged factor replacement.

  18. ASH External Web Portal (External Portal) -

    Data.gov (United States)

    Department of Transportation — The ASH External Web Portal is a web-based portal that provides single sign-on functionality, making the web portal a single location from which to be authenticated...

  19. Post-external dacryocystorhinostomy lagophthalmos.

    Science.gov (United States)

    Odat, Thabit A; Odat, Haitham A; Khraisat, Heba; Odat, Mohannad A; Alzoubi, Firas Q

    2015-06-01

    To describe lagophthalmos and eyelid closure abnormality after external dacryocystorhinostomy (DCR). A retrospective review of medical records and postoperative photographs of 79 patients who underwent external DCR for nasolacrimal duct obstruction and developed eyelid closure abnormality and lagophthalmos with or without exposure keratopathy was conducted. Collected data included age, sex, indication for surgery, laterality, length and type of incision, length of follow-up duration, presence of punctate epithelial keratopathy, and time for resolution of eyelid closure abnormalities. Twenty-seven patients with 28 external dacryocystorhinostomy had postoperative eyelid closure abnormalities. Male to female ratio was 1:6. The mean age was 40.1 years (range 9-80 years). All surgeries were performed through diagonal skin incision. Lagophthalmos involving the medial third of the palpebral fissure was noticed in 28.6 % of cases. All patients had hypometric blink mainly of the upper eyelid. One patient had punctate epithelial keratopathy. Resolution of lagophthalmos was noticed over a period of 1-5 weeks with an average of 3 weeks. None of the patients continued to have residual hypometric blink or punctate keratopathy at the last follow-up time. The mean follow-up period was 4.2 months (range 3-6 months). Eyelid closure abnormality and lagophthalmos after external DCR are underestimated problems. Spontaneous resolution is seen in all cases weeks to months after surgery.

  20. Forced Snaking

    Science.gov (United States)

    Ponedel, Benjamin; Knobloch, Edgar

    2016-11-01

    We study spatial localization in the real subcritical Ginzburg-Landau equation ut =m0 u +m1 cos2/π l x u +uxx +d | u | 2 u -| u | 4 u with spatially periodic forcing. When d > 0 and m1 = 0 this equation exhibits bistability between the trivial state u = 0 and a homogeneous nontrivial state u =u0 with stationary localized structures which accumulate at the Maxwell point m0 = - 3d2 / 16 . When spatial forcing is included its wavelength is imprinted on u0 creating conditions favorable to front pinning and hence spatial localization. We use numerical continuation to show that under appropriate conditions such forcing generates a sequence of localized states organized within a snakes-and-ladders structure centered on the Maxwell point, and refer to this phenomenon as forced snaking. We determine the stability properties of these states and show that longer lengthscale forcing leads to stationary trains consisting of a finite number of strongly localized, weakly interacting pulses exhibiting foliated snaking.

  1. Force Characteristics in Continuous Path Controlled Crankpin Grinding

    Institute of Scientific and Technical Information of China (English)

    ZHANG Manchao; YAO Zhenqiang

    2015-01-01

    Recent research on the grinding force involved in cylindrical plunge grinding has focused mainly on steady-state conditions. Unlike in conventional external cylindrical plunge grinding, the conditions between the grinding wheel and the crankpin change periodically in path controlled grinding because of the eccentricity of the crankpin and the constant rotational speed of the crankshaft. The objective of this study is to investigate the effects of various grinding conditions on the characteristics of the grinding force during continuous path controlled grinding. Path controlled plunge grinding is conducted at a constant rotational speed using a cubic boron nitride (CBN) wheel. The grinding force is determined by measuring the torque. The experimental results show that the force and torque vary sinusoidally during dry grinding and load grinding. The variations in the results reveal that the resultant grinding force and torque decrease with higher grinding speeds and increase with higher peripheral speeds of the pin and higher grinding depths. In path controlled grinding, unlike in conventional external cylindrical plunge grinding, the axial grinding force cannot be disregarded. The speeds and speed ratios of the workpiece and wheel are also analyzed, and the analysis results show that up-grinding and down-grinding occur during the grinding process. This paper proposes a method for describing the force behavior under varied process conditions during continuous path controlled grinding, which provides a beneficial reference for describing the material removal mechanism and for optimizing continuous controlled crankpin grinding.

  2. Historically defined autobiographical periods

    DEFF Research Database (Denmark)

    Brown, Norman R.; Hansen, Tia G. B.; Lee, Peter J.;

    2012-01-01

    The chapter reviews a research programme that has demonstrated the existence of historically defined autobiographical periods and identified the conditions that bring them about. Data from four samples of World War II-generation adults show that historically defined autobiographical periods endure...... over time and theoretical implications are discussed, notably by introducing a new approach to autobiographical memory, Transition Theory, which assumes that autobiographical memory is organized by transitional events that can be selfinitiated or externally imposed - historically defined...

  3. Organizational Change in the United States Air Force

    Science.gov (United States)

    2003-01-14

    organizational change on the part of the Air Force. This exploratory study analyzes the transition between the Cold War and post-Cold War periods to identify key variables in the organizational change process that might be susceptible to policy intervention. In particular, it highlights the importance of an external change agent in the form of a directed change in mission, or an internal change agent in the form of organizational learning, as essential factors in transforming the Air Force’s organizational strategy, which is the first step in

  4. External radiation surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, E.J.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report describes how external radiation was measured, how surveys were performed, and the results of these measurements and surveys. External radiation exposure rates were measured at locations on and off the Hanford Site using thermoluminescent dosimeters (TLD). External radiation and contamination surveys were also performed with portable radiation survey instruments at locations on and around the Hanford Site.

  5. Nonlinear Dynamic Force Spectroscopy

    CERN Document Server

    Björnham, Oscar

    2016-01-01

    Dynamic force spectroscopy (DFS) is an experimental technique that is commonly used to assess information of the strength, energy landscape, and lifetime of noncovalent bio-molecular interactions. DFS traditionally requires an applied force that increases linearly with time so that the bio-complex under investigation is exposed to a constant loading rate. However, tethers or polymers can modulate the applied force in a nonlinear regime. For example, bacterial adhesion pili and polymers with worm-like chain properties are examples of structures that show nonlinear force responses. In these situations, the theory for traditional DFS cannot be readily applied. In this work we expand the theory for DFS to also include nonlinear external forces while still maintaining compatibility with the linear DFS theory. To validate the theory we modeled a bio-complex expressed on a stiff, an elastic and a worm-like chain polymer, using Monte Carlo methods, and assessed the corresponding rupture force spectra. It was found th...

  6. Modeling dynamic behavior of superconducting maglev systems under external disturbances

    Science.gov (United States)

    Huang, Chen-Guang; Xue, Cun; Yong, Hua-Dong; Zhou, You-He

    2017-08-01

    For a maglev system, vertical and lateral displacements of the levitation body may simultaneously occur under external disturbances, which often results in changes in the levitation and guidance forces and even causes some serious malfunctions. To fully understand the effect of external disturbances on the levitation performance, in this work, we build a two-dimensional numerical model on the basis of Newton's second law of motion and a mathematical formulation derived from magnetoquasistatic Maxwell's equations together with a nonlinear constitutive relation between the electric field and the current density. By using this model, we present an analysis of dynamic behavior for two typical maglev systems consisting of an infinitely long superconductor and a guideway of different arrangements of infinitely long parallel permanent magnets. The results show that during the vertical movement, the levitation force is closely associated with the flux motion and the moving velocity of the superconductor. After being disturbed at the working position, the superconductor has a disturbance-induced initial velocity and then starts to periodically vibrate in both lateral and vertical directions. Meanwhile, the lateral and vertical vibration centers gradually drift along their vibration directions. The larger the initial velocity, the faster their vibration centers drift. However, the vertical drift of the vertical vibration center seems to be independent of the direction of the initial velocity. In addition, due to the lateral and vertical drifts, the equilibrium position of the superconductor in the maglev systems is not a space point but a continuous range.

  7. 21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended to...

  8. Forced and internal variability in temperature simulations and reconstructions of the Common Era

    Science.gov (United States)

    Fernández-Donado, Laura; Fidel González-Rouco, J.; Garcia-Bustamante, Elena; Smerdon, Jason S.; Luterbacher, Juerg; Raible, Christoph C.

    2016-04-01

    The relatively short ranges of external forcing variability within the CE represent a challenge in as much as the consistency between simulations and reconstructions can be affected by the large uncertainties in their respective responses to the external forcings. One of the core questions within this work relates therefore the extent to which a straight response to the external forcing can be identified during the period under study and whether this signal is common to simulated and reconstructed temperature. This study is based on an exhaustive compilation, analysis and intercomparison of the available hemispherical and global temperature reconstructions as well as a complete ensemble of simulations including both PMIP3/CMIP5 and non-PMIP3 model experiments. In addition, the various external forcing configurations applied to the models are characterized and a Total External Forcing, including all the individual forcing contributors, is developed for each experiment. Based on the linear relationship found at multidecadal and longer timescales during the last millennium between the temperature and the total external forcing, a quantitative metric of the ratio of response, the so-called Last Millennium Transient Climate Response (LMTCR), is obtained and compared for simulations and reconstructions. Within the LMTCR context, a significant quantitative consistency between the simulations and reconstructions is addressed. This work also offers a discussion about the impact that a range of generally accepted methodological approaches might have on the reconstructed ensemble uncertainties and their influences on model-data comparison exercises. A segregation among the various existing spatial targets within the NH, based on the different level of temperatura variability observed in the series, suggests a lower level of model-data consistency during the MCA than previously reported.

  9. MGR External Events Hazards Analysis

    Energy Technology Data Exchange (ETDEWEB)

    L. Booth

    1999-11-06

    The purpose and objective of this analysis is to apply an external events Hazards Analysis (HA) to the License Application Design Selection Enhanced Design Alternative 11 [(LADS EDA II design (Reference 8.32))]. The output of the HA is called a Hazards List (HL). This analysis supersedes the external hazards portion of Rev. 00 of the PHA (Reference 8.1). The PHA for internal events will also be updated to the LADS EDA II design but under a separate analysis. Like the PHA methodology, the HA methodology provides a systematic method to identify potential hazards during the 100-year Monitored Geologic Repository (MGR) operating period updated to reflect the EDA II design. The resulting events on the HL are candidates that may have potential radiological consequences as determined during Design Basis Events (DBEs) analyses. Therefore, the HL that results from this analysis will undergo further screening and analysis based on the criteria that apply during the performance of DBE analyses.

  10. Influence of external potentials on heterogeneous diffusion processes

    Science.gov (United States)

    Kazakevičius, Rytis; Ruseckas, Julius

    2016-09-01

    In this paper we consider heterogeneous diffusion processes with the power-law dependence of the diffusion coefficient on the position and investigate the influence of external forces on the resulting anomalous diffusion. The heterogeneous diffusion processes can yield subdiffusion as well as superdiffusion, depending on the behavior of the diffusion coefficient. We assume that not only the diffusion coefficient but also the external force has a power-law dependence on the position. We obtain analytic expressions for the transition probability in two cases: when the power-law exponent in the external force is equal to 2 η -1 , where 2 η is the power-law exponent in the dependence of the diffusion coefficient on the position, and when the external force has a linear dependence on the position. We found that the power-law exponent in the dependence of the mean square displacement on time does not depend on the external force; this force changes only the anomalous diffusion coefficient. In addition, the external force having the power-law exponent different from 2 η -1 limits the time interval where the anomalous diffusion occurs. We expect that the results obtained in this paper may be relevant for a more complete understanding of anomalous diffusion processes.

  11. Dynamics of Solid Body in Magnetic Suspension under Periodic Excitation

    Directory of Open Access Journals (Sweden)

    A. M. Gouskov

    2017-01-01

    Full Text Available The article studies dynamics of ferromagnetic body in hybrid magnetic suspension (HMS. The body is supposed to have one degree of freedom and a nonlinear magnetic force dependence on the current and displacement. The magnetic force induced in the HMS is divided into a passive component and an active one. Specifying the law of current variation in the coil allows us to generate nonlinear oscillations under electromagnet action. To provide periodic excitation the appropriate law of the current variation in the electromagnet coil is proposed. The mathematical model includes external periodic step-excitation. The equation of motion is formed. The scales of similarity are highlighted in the system, and the equation of motion is reduced to dimensionless form.The motion dynamics is studied numerically. The relaxation method was used to determine the periodic motions at different values of dimensionless frequency of the electromagnet excitation as well as to estimate the influence of other dimensionless parameters on the system dynamics. The amplitude-frequency curve analysis allows us to come to conclusion that the nature of system nonlinearity is rigid. Adding the external periodic step-excitation leads to the qualitative change in the nature of movement. This points to the occurrence of bifurcation.

  12. Period Cramps

    Science.gov (United States)

    ... Too Tall or Too Short All About Puberty Period Cramps KidsHealth > For Kids > Period Cramps Print A ... re a girl who gets them. What Are Period Cramps? Lots of girls experience cramps before or ...

  13. Semantic Externalism and Self Knowledge: Privileged Access to the World

    OpenAIRE

    Sawyer, Sarah

    2008-01-01

    The thesis is concerned to defend the compatibility of two plausible claims about the mind; semantic externalism and privileged access. It is further concerned to demonstrate one important implication of the conjunction of semantic externalism and privileged access, an implication which forces the rejection of the dichotomy between knowledge of one’s mind and knowledge of one’s world. Chapter one is a presentation of semantic externalism. Chapter two is a presentation of the claim of privileg...

  14. The Research and Development of the External Magnetic Field Acting on Electro-Deposition Process

    OpenAIRE

    Wu Menghua; Jia Weiping

    2016-01-01

    The research and development status of the electro-deposition technology under the action of external magnetic field are introduced. The basic characteristics and applied manners of external magnetic field in electro-deposition process are summarized. The acting principle of external magnetic field, the effects of magnetic hydrodynamics (MHD) caused by the Lorentz force, and the acting of magnetic force on the metal ions and particles are described. The main actions of external magnetic field...

  15. Externally Verifiable Oblivious RAM

    Directory of Open Access Journals (Sweden)

    Gancher Joshua

    2017-04-01

    Full Text Available We present the idea of externally verifiable oblivious RAM (ORAM. Our goal is to allow a client and server carrying out an ORAM protocol to have disputes adjudicated by a third party, allowing for the enforcement of penalties against an unreliable or malicious server. We give a security definition that guarantees protection not only against a malicious server but also against a client making false accusations. We then give modifications of the Path ORAM [15] and Ring ORAM [9] protocols that meet this security definition. These protocols both have the same asymptotic runtimes as the semi-honest original versions and require the external verifier to be involved only when the client or server deviates from the protocol. Finally, we implement externally verified ORAM, along with an automated cryptocurrency contract to use as the external verifier.

  16. External Beam Therapy (EBT)

    Science.gov (United States)

    ... Esophageal Cancer Treatment Head and Neck Cancer Treatment Lung Cancer Treatment Prostate Cancer Treatment Brain Tumor Treatment Why is ... Radiation Oncology) Breast Cancer Treatment Esophageal Cancer Treatment Lung Cancer Treatment Images related to External Beam Therapy (EBT) Sponsored ...

  17. MALIGNANT EXTERNAL OTITIS

    OpenAIRE

    Massoud Moghaddam

    1993-01-01

    Two case reports of malignant external otitis in the elderly diabetics and their complications and management with regard to our experience at Amir Alam Hospital, Department of ENT will be discussed here.

  18. Checklists for external validity

    DEFF Research Database (Denmark)

    Dyrvig, Anne-Kirstine; Kidholm, Kristian; Gerke, Oke;

    2014-01-01

    RATIONALE, AIMS AND OBJECTIVES: The quality of the current literature on external validity varies considerably. An improved checklist with validated items on external validity would aid decision-makers in judging similarities among circumstances when transferring evidence from a study setting...... to an implementation setting. In this paper, currently available checklists on external validity are identified, assessed and used as a basis for proposing a new improved instrument. METHOD: A systematic literature review was carried out in Pubmed, Embase and Cinahl on English-language papers without time restrictions....... The retrieved checklist items were assessed for (i) the methodology used in primary literature, justifying inclusion of each item; and (ii) the number of times each item appeared in checklists. RESULTS: Fifteen papers were identified, presenting a total of 21 checklists for external validity, yielding a total...

  19. Studies of phase return map and symbolic dynamics in a periodically driven Hodgkin—Huxley neuron

    Science.gov (United States)

    Ding, Jiong; Zhang, Hong; Tong, Qin-Ye; Chen, Zhuo

    2014-02-01

    How neuronal spike trains encode external information is a hot topic in neurodynamics studies. In this paper, we investigate the dynamical states of the Hodgkin—Huxley neuron under periodic forcing. Depending on the parameters of the stimulus, the neuron exhibits periodic, quasiperiodic and chaotic spike trains. In order to analyze these spike trains quantitatively, we use the phase return map to describe the dynamical behavior on a one-dimensional (1D) map. According to the monotonicity or discontinuous point of the 1D map, the spike trains are transformed into symbolic sequences by implementing a coarse-grained algorithm — symbolic dynamics. Based on the ordering rules of symbolic dynamics, the parameters of the external stimulus can be measured in high resolution with finite length symbolic sequences. A reasonable explanation for why the nervous system can discriminate or cognize the small change of the external signals in a short time is also presented.

  20. Migration with fiscal externalities.

    Science.gov (United States)

    Hercowitz, Z; Pines, D

    1991-11-01

    "This paper analyses the distribution of a country's population among regions when migration involves fiscal externalities. The main question addressed is whether a decentralized decision making [by] regional governments can produce an optimal population distribution...or a centralized intervention is indispensable, as argued before in the literature.... It turns out that, while with costless mobility the fiscal externality is fully internalized by voluntary interregional transfers, with costly mobility, centrally coordinated transfers still remain indispensable for achieving the socially optimal allocation."

  1. Sen cycles and externalities

    OpenAIRE

    Piggins, Ashley; Salerno, Gillian

    2016-01-01

    It has long been understood that externalities of some kind are responsible for Sen’s (1970) theorem on the impossibility of a Paretian liberal. However, Saari and Petron (2006) show that for any social preference cycle generated by combining the weak Pareto principle and individual decisiveness, every decisive individual must suffer at least one strong negative externality. We show that this fundamental result only holds when individual preferences are strict. Building on their contribution,...

  2. Rank One Strange Attractors in Periodically Kicked Predator-Prey System with Time-Delay

    Science.gov (United States)

    Yang, Wenjie; Lin, Yiping; Dai, Yunxian; Zhao, Huitao

    2016-06-01

    This paper is devoted to the study of the problem of rank one strange attractor in a periodically kicked predator-prey system with time-delay. Our discussion is based on the theory of rank one maps formulated by Wang and Young. Firstly, we develop the rank one chaotic theory to delayed systems. It is shown that strange attractors occur when the delayed system undergoes a Hopf bifurcation and encounters an external periodic force. Then we use the theory to the periodically kicked predator-prey system with delay, deriving the conditions for Hopf bifurcation and rank one chaos along with the results of numerical simulations.

  3. A modelling study of the influence of anomalous wind forcing over the Barents Sea on the Atlantic water flow to the Arctic Ocean in the period 1979-2004

    Science.gov (United States)

    Marciniak, Jakub; Schlichtholz, Pawel; Maslowski, Wieslaw

    2016-04-01

    Arctic climate system is influenced by oceanic heat transport with the Atlantic water (AW) streaming towards the Arctic Ocean in two branches, through the deep Fram Strait and the shallow Barents Sea. In Fram Strait, the AW submerges below the Polar surface water and then flows cyclonically along the margin of the Arctic Ocean as a subsurface water mass in the Arctic Slope Current. In contrast to the Fram Strait branch, which is the major source of heat for the Arctic Ocean, most of the heat influx to the Barents Sea through the Barents Sea opening (BSO) is passed to the atmosphere. Only cold remnants of AW outflow to the Arctic Ocean through the northeastern gate of the Barents Sea. Some AW entering the Barents Sea recirculates westward, contributing to an outflow from the Barents Sea through the BSO along the shelf slope south of Bear Island, in the Bear Island Slope Current. Even though the two-branched AW flow toward the Arctic Ocean has been known for more than a century, little is known about co-variability of heat fluxes in the two branches, its mechanisms and climatic implications. Recent studies indicate that the Bear Island Slope Current may play a role in this co-variability. Here, co-variability of the flow through the BSO and Fram Strait is investigated using a pan-Arctic coupled ice-ocean hindcast model run for the period 1979-2004 and forced with daily atmospheric data from the ECMWF. Significant wintertime co-variability between the volume transport in the Bear Island and Arctic slope currents and its link to wind forcing over the Barents Sea is confirmed. It is found that the volume transports in these currents are, however, not correlated in the annual mean and that the wintertime co-variability of these currents has no immediate effect on either the net heat flux through the BSO or the net heat flux divergence in the Barents Sea. It is shown that the main climatic effect of wind forcing over the northern Barents Sea shelf is to induce temperature

  4. Periodic arrays of pinning centers in thin vanadium films.

    Energy Technology Data Exchange (ETDEWEB)

    Brueck, S. R. J.; Chung, K.; Crabtree, G.; DeLong, L. E.; Hesketh, P. J.; Ilic, B.; Metlushko, V.; Watkins, B.; Welp, U.; Zhang, Z.

    1997-07-13

    Commensurability effects between the superconducting flux line lattice and a square lattice (period d=1{micro}m and diameter D=0.4{micro}m) of submicron holes in 1500 {angstrom} vanadium films were studied by atomic force microscopy, DC magnetization, AC susceptibility, magnetoresistivity and I-V measurements. Peaks in the magnetization and critical current at matching fields are found to depend nonlinearly upon the value of external AC field or current, as well as the inferred symmetry of the flux line lattice.

  5. Parameter-induced stochastic resonance with a periodic signal

    Institute of Scientific and Technical Information of China (English)

    Li Jian-Long; Xu Bo-Hou

    2006-01-01

    In this paper conventional stochastic resonance (CSR) is realized by adding the noise intensity. This demonstrates that tuning the system parameters with fixed noise can make the noise play a constructive role and realize parameterinduced stochastic resonance (PSR). PSR can be interpreted as changing the intrinsic characteristic of the dynamical system to yield the cooperative effect between the stochastic-subjected nonlinear system and the external periodic force. This can be realized at any noise intensity, which greatly differs from CSR that is realized under the condition of the initial noise intensity not greater than the resonance level. Moreover, it is proved that PSR is different from the optimization of system parameters.

  6. External Force Damage Simulation of Submarine High-voltage Cable Based on Distributed Fiber Optic Sensor Technology%基于分布式光纤传感技术的高压海底电缆外力损坏仿真

    Institute of Scientific and Technical Information of China (English)

    陆莹; 黄辉

    2012-01-01

    高压海底电缆的安全稳定运行对于海上能源的开发具有重要的作用,海缆电缆的损坏主要由外力引起,针对分布式光纤传感器在线监测高压海底电缆运行状况的方法,利用有限元软件ANSYS建立XLPE高压海底电缆模型,仿真分析海底电缆受到外力损坏时,内部物理量的变化,为分布式光纤传感器在线监测高压海底电缆运行状态提供参考。%Safety and stable operation of submarine high-voltage cable has played an important role in the development of Marine energy. However, submarine high-voltage cable was mainly damaged by external forces. According to the method for operation state of submarine high-voltage cable using on-line monitoring technology based on distributed fiber optic sensor, the model of the XLPE submarine high-voltage cable was gained by using finite element software ANSYS. Then, based on the model, the change of internal physical quantities were researched ,when submarine high-voltage cable was damaged by external force, with the function to provide the practical reference for running state of submarine high-voltage cable monitoring on-line based on distributed fiber optic sensor.

  7. Environmental external effects from wind power based on the EU ExternE methodology

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1998-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  8. Externality or sustainability economics?

    Energy Technology Data Exchange (ETDEWEB)

    Bergh, Jeroen C.J.M. van den [ICREA, Barcelona (Spain); Department of Economics and Economic History and Institute for Environmental Science and Technology, Universitat Autonoma de Barcelona (Spain)

    2010-09-15

    In an effort to develop 'sustainability economics' Baumgaertner and Quaas (2010) neglect the central concept of environmental economics-'environmental externality'. This note proposes a possible connection between the concepts of environmental externality and sustainability. In addition, attention is asked for other aspects of 'sustainability economics', namely the distinction weak/strong sustainability, spatial sustainability and sustainable trade, distinctive sustainability policy, and the ideas of early 'sustainability economists'. I argue that both sustainability and externalities reflect a systems perspective and propose that effective sustainability solutions require that more attention is given to system feedbacks, notably other-regarding preferences and social interactions, and energy and environmental rebound. The case of climate change and policy is used to illustrate particular statements. As a conclusion, a list of 20 insights and suggestions for research is offered. (author)

  9. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  10. Correlation study of the relationship between gravity center movement and bite force during the mixed dentition period%混合牙列期身体重心动摇和咬合力的相关性研究

    Institute of Scientific and Technical Information of China (English)

    杜小沛; 纪莹; 陆海涛; 张婷婷; 邱伟

    2016-01-01

    目的:调查混合牙列期身体重心动摇与咬合力之间的关系。方法56名处于Hellman咬合发育Ⅲ期A阶段的健康小学生纳入研究。通过检查咬合平衡中点与中线的距离( X)关系,X≤5 mm被划分为正中组,X>5 mm被划分为偏移组。使用自动姿态分析系统测定了身体平衡相关开闭眼时的重心动摇距离、重心动摇面积。使用牙齿压力感应装置Dental Prescale®测定了咬合接触面积、平均咬合力、最大咬合压力,咬合力和咬合平衡。结果咬合接触面积和咬合力的测试结果男女分别为18.1 mm2、712.2 N和14.1 mm2、541.8 N,差异均具有统计学意义(P<0.05)。咬合平衡中点正中组与偏移组的咬合接触面积、咬合力之间差异具有统计学意义(P <0.05)。咬合平衡中点正中组开、闭眼时期的重心动摇距离、面积明显小于偏移组,咬合平衡与开、闭眼时期的重心动摇距离、面积有关且具有统计学意义(P<0.05)。重心动摇稳定组的咬合接触面积大于动摇组,两者差异具有统计学意义(P<0.05)。结论 Hellman咬合发育Ⅲ期A阶段儿童咬合平衡和人体重心动摇存在相关性,咬合接触面积与身体重心动摇相互影响。%Objective To investigate the relationship between gravity center movement and bite force during the mixed dentition period. Methods Fifty-six healthy children with Hellman's Dental AgeⅢ A were selected from an ele-mentary school. The body balance, distance and area of gravity center movement ( GCM) were measured with automatic posture analytical devices. Occlusal abilities were measured with pressure-sensitive sheets ( Dental Prescale® ) , including occlusal contacts area, average occlusal pressure, maximum occlusal pressure, occlusal force and occlusal balance. Re-sults The occlusal contact area and bite force test results of male and female group were 18. 1 mm2 , 712. 2 N and 14. 1 mm2, 541. 8 N, The differences were statistically

  11. Stochastic Control - External Models

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    2005-01-01

    This note is devoted to control of stochastic systems described in discrete time. We are concerned with external descriptions or transfer function model, where we have a dynamic model for the input output relation only (i.e.. no direct internal information). The methods are based on LTI systems...

  12. Productivity Change and Externalities

    DEFF Research Database (Denmark)

    Kravtsova, Victoria

    2014-01-01

    firms and the economy as a whole. The approach used in the current research accounts for different internal as well as external factors that individual firms face and evaluates the effect on changes in productivity, technology as well as the efficiency of domestic firms. The empirical analysis focuses...... change in different types of firms and sectors of the economy...

  13. Multiple external root resorption.

    Science.gov (United States)

    Yusof, W Z; Ghazali, M N

    1989-04-01

    Presented is an unusual case of multiple external root resorption. Although the cause of this resorption was not determined, several possibilities are presented. Trauma from occlusion, periodontal and pulpal inflammation, and resorption of idiopathic origin are all discussed as possible causes.

  14. Unidirectional Transport of Ferromagnetic Particles in a Viscous LiquidInduced by the Magnus Force

    Directory of Open Access Journals (Sweden)

    S.I. Denisov

    2016-10-01

    Full Text Available We study the unidirectional motion of spherical ferromagnetic particles suspended in a viscous liquid and subjected to the action of an external periodic force and a non-uniformly rotating magnetic field. In the case when the translational and rotational motions of particles are characterized by small Reynolds numbers, we propose a system of equations that describes their dynamics and that accounts for the influence of the Magnus force. Theoretical and numerical analysis of the steady-state solution of this system of equations is carried out, the average velocity of unidirectional (drift motion of particles is calculated, and the dependence of the average velocity on the characteristics of particles, liquid, external force and magnetic field is studied.

  15. Surface diffusion of a Brownian particle subjected to an external harmonic noise

    Science.gov (United States)

    Bai, Zhan-Wu; Ding, Li-Ping

    2017-05-01

    Langevin simulation is performed to investigate the diffusion coefficient of a Brownian particle subjected to an external harmonic noise in a two-dimensional coupled periodic potential. Resonant diffusion phenomenon is observed as a result of the coupling between the central frequency of the spectral density of the harmonic noise and the frequency of the potential well bottom. The diffusion coefficient presents approximately linear functions of the strengths of the internal and external noises for low values of the strengths, these functions can be understood by the local linearization approximation of the potential force. The damping coefficient dependence of the diffusion coefficient in lower damping is well fitted by a negative power function, as an internal Gaussian white noise case does, but with a power whose absolute value is larger than 1.

  16. Periodic paralysis.

    Science.gov (United States)

    Fontaine, Bertrand

    2008-01-01

    Periodic paralyses are rare diseases characterized by severe episodes of muscle weakness concomitant to variations in blood potassium levels. It is thus usual to differentiate hypokalemic, normokalemic, and hyperkalemic periodic paralysis. Except for thyrotoxic hypokalemic periodic paralysis and periodic paralyses secondary to permanent changes of blood potassium levels, all of these diseases are of genetic origin, transmitted with an autosomal-dominant mode of inheritance. Periodic paralyses are channelopathies, that is, diseases caused by mutations in genes encoding ion channels. The culprit genes encode for potassium, calcium, and sodium channels. Mutations of the potassium and calcium channel genes cause periodic paralysis of the same type (Andersen-Tawil syndrome or hypokalemic periodic paralysis). In contrast, distinct mutations in the muscle sodium channel gene are responsible for all different types of periodic paralyses (hyper-, normo-, and hypokalemic). The physiological consequences of the mutations have been studied by patch-clamp techniques and electromyography (EMG). Globally speaking, ion channel mutations modify the cycle of muscle membrane excitability which results in a loss of function (paralysis). Clinical physiological studies using EMG have shown a good correlation between symptoms and EMG parameters, enabling the description of patterns that greatly enhance molecular diagnosis accuracy. The understanding of the genetics and pathophysiology of periodic paralysis has contributed to refine and rationalize therapeutic intervention and will be without doubts the basis of further advances.

  17. Clinical effect of trichosanthes arctium lappa decoction combined with external application of mirabilite in the treatment of acute mastitis stagnation period%瓜蒌牛蒡汤加减联合芒硝外敷治疗急性乳腺炎郁滞期的临床观察

    Institute of Scientific and Technical Information of China (English)

    李幸运

    2014-01-01

    目的:探讨瓜蒌牛蒡汤加减联合芒硝外敷治疗急性乳腺炎郁滞期的临床效果,进一步指导临床。方法选取2012年1月~2014年1月在本院门诊治疗的急性乳腺炎郁滞期患者60例,按照随机对照的原则,将患者分为观察组和对照组,每组各30例,观察组30例患者给予瓜蒌牛蒡汤加减联合芒硝外敷治疗,对照组30例患者给予单纯的硫酸镁湿热敷治疗,观察对比两组的临床治疗效果以及治疗时间。结果观察组治疗总有效率明显优于对照组,差异具有统计学意义(P<0.05),观察组的治疗时间明显少于对照组,差异具有统计学意义(P<0.05)。结论瓜蒌牛蒡汤加减联合芒硝外敷治疗急性乳腺炎郁滞期临床疗效显著,降低了脓肿的形成,有效的减轻患者的痛苦,保证母乳喂养率。%Objective To discuss the clinical effect of trichosanthes arctium lappa decoction combined with external application of mirabilite in the treatment of acute mastitis stagnation period for further clinical guide. Methods Choosing 60 patients with acute mastitis stagnation period from January 2012 to January 2014 in our hospital, outpatient treatment of patients, according to the principle of randomized controlled, the patients were divided into observation group and control group, 30 cases in each group, the observation group of 30 cases were treated with trichosanthes arctium lappa decoction combined with external application of mirabilite treatment, 30 cases in the control group were treated with magnesium sulfate wet compress simple treatment, the clinical therapeutic effect of two groups were compared and the treatment time. Results In observation group, the total efficiency of treatment was better than the control group, the difference was significant, with statistical significance(P<0.05), the treatment time of observation group was less than that of control group, the difference was significant, with

  18. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summaris...

  19. The External Mind

    DEFF Research Database (Denmark)

    The External Mind: an Introduction by Riccardo Fusaroli, Claudio Paolucci pp. 3-31 The sign of the Hand: Symbolic Practices and the Extended Mind by Massimiliano Cappuccio, Michael Wheeler pp. 33-55 The Overextended Mind by Shaun Gallagher pp. 57-68 The "External Mind": Semiotics, Pragmatism......, Extended Mind and Distributed Cognition by Claudio Paolucci pp. 69-96 The Social Horizon of Embodied Language and Material Symbols by Riccardo Fusaroli pp. 97-123 Semiotics and Theories of Situated/Distributed Action and Cognition: a Dialogue and Many Intersections by Tommaso Granelli pp. 125-167 Building...... Action in Public Environments with Diverse Semiotic Resources by Charles Goodwin pp. 169-182 How Marking in Dance Constitutes Thinking with the Body by David Kirsh pp. 183-214 Ambiguous Coordination: Collaboration in Informal Science Education Research by Ivan Rosero, Robert Lecusay, Michael Cole pp. 215-240...

  20. External-Memory Multimaps

    CERN Document Server

    Angelino, Elaine; Mitzenmacher, Michael; Thaler, Justin

    2011-01-01

    Many data structures support dictionaries, also known as maps or associative arrays, which store and manage a set of key-value pairs. A \\emph{multimap} is generalization that allows multiple values to be associated with the same key. For example, the inverted file data structure that is used prevalently in the infrastructure supporting search engines is a type of multimap, where words are used as keys and document pointers are used as values. We study the multimap abstract data type and how it can be implemented efficiently online in external memory frameworks, with constant expected I/O performance. The key technique used to achieve our results is a combination of cuckoo hashing using buckets that hold multiple items with a multiqueue implementation to cope with varying numbers of values per key. Our external-memory results are for the standard two-level memory model.

  1. Automatic Planning of External Search Engine Optimization

    Directory of Open Access Journals (Sweden)

    Vita Jasevičiūtė

    2015-07-01

    Full Text Available This paper describes an investigation of the external search engine optimization (SEO action planning tool, dedicated to automatically extract a small set of most important keywords for each month during whole year period. The keywords in the set are extracted accordingly to external measured parameters, such as average number of searches during the year and for every month individually. Additionally the position of the optimized web site for each keyword is taken into account. The generated optimization plan is similar to the optimization plans prepared manually by the SEO professionals and can be successfully used as a support tool for web site search engine optimization.

  2. Irregular Periods

    Science.gov (United States)

    ... blood become too low or too high. Some women have irregular periods because their bodies produce too much androgen, which is a hormone that causes increased muscle mass, facial hair, and deepening of the voice in males and ...

  3. Period Pain

    Science.gov (United States)

    ... You may also have other symptoms, such as lower back pain, nausea, diarrhea, and headaches. Period pain is not ... Taking a hot bath Doing relaxation techniques, including yoga and meditation You might also try taking over- ...

  4. Magnetic force of piezo electric cantilever energy harvesting system with an externally applied magnetic field based on magnetizing current metho d%外加磁场压电悬臂梁能量采集系统的磁化电流法磁力研究∗

    Institute of Scientific and Technical Information of China (English)

    谭丹; 冷永刚; 范胜波; 高毓璣

    2015-01-01

    以外加磁场压电悬臂梁能量采集系统结构为研究对象,根据磁化电流方法探讨了具有悬臂梁特征的系统结构的磁场作用力及其计算方法,给出了相应的磁力计算模型,并将计算结果与实验数据进行了对比。研究表明,磁化电流方法导出的磁力计算模型存在偏差,其磁力计算误差随着磁铁间距缩小而增大。通过引入悬臂梁末端磁铁的偏转角度,对磁化电流法计算模型进行改进,得到合理的外加磁场压电悬臂梁能量采集系统的磁力计算模型,为该能量采集系统的进一步研究提供了可靠的磁力计算理论依据。%This paper focuses on the piezoelectric cantilever energy harvesting system with an externally applied magnetic field. The calculation method and model for the magnetic force are proposed from the magnetizing current method, and the calculation results are compared with a set of experimental data. The study shows that there is a deviation in the calculation model derived by the magnetizing current method, which increases as the distance between two magnets decreases. The calculation model is improved by introducing the deflection angle of the magnet at the end of the cantilever beam, and is reliable to calculate the magnetic force of piezoelectric cantilever energy harvesting system with an externally applied magnetic field for further studying this energy harvesting system.

  5. 21 CFR 870.3600 - External pacemaker pulse generator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External pacemaker pulse generator. 870.3600... pacemaker pulse generator. (a) Identification. An external pacemaker pulse generator is a device that has a power supply and electronic circuits that produce a periodic electrical pulse to stimulate the...

  6. Labor Force

    Science.gov (United States)

    Occupational Outlook Quarterly, 2012

    2012-01-01

    The labor force is the number of people ages 16 or older who are either working or looking for work. It does not include active-duty military personnel or the institutionalized population, such as prison inmates. Determining the size of the labor force is a way of determining how big the economy can get. The size of the labor force depends on two…

  7. Attractive and repulsive quantum forces from dimensionality of space

    DEFF Research Database (Denmark)

    Bialynicki-Birula, I.; Cirone, M.A.; Dahl, Jens Peder

    2002-01-01

    Two particles of identical mass attract and repel each other even when there exist no classical external forces and their average relative momentum vanishes. This quantum force depends crucially on the number of dimensions of space.......Two particles of identical mass attract and repel each other even when there exist no classical external forces and their average relative momentum vanishes. This quantum force depends crucially on the number of dimensions of space....

  8. Regularization by External Variables

    DEFF Research Database (Denmark)

    Bossolini, Elena; Edwards, R.; Glendinning, P. A.

    2016-01-01

    Regularization was a big topic at the 2016 CRM Intensive Research Program on Advances in Nonsmooth Dynamics. There are many open questions concerning well known kinds of regularization (e.g., by smoothing or hysteresis). Here, we propose a framework for an alternative and important kind of regula...... of regularization, by external variables that shadow either the state or the switch of the original system. The shadow systems are derived from and inspired by various applications in electronic control, predator-prey preference, time delay, and genetic regulation....

  9. External Costs as Driving Forces of Land Use Changes

    Directory of Open Access Journals (Sweden)

    Dirk Loehr

    2010-04-01

    Full Text Available Land conversion is often not carried out in a sustainable way. The loss of arable land and biodiversity, concern about food security and rising costs of infrastructure due to urban sprawl are just some of the problems under discussion. This paper compares Germany, China and Cambodia. The article points out that, despite huge differences in institutions and governance, unsustainable land use changes mostly have some patterns in common: The beneficiaries of land conversion are often well-organized actors, whereas the costs of land conversion are often shifted to poorly organized groups and to society as a whole. A sustainable land use policy has to look for a better coupling of benefits and costs of land use changes. In order to achieve this goal, the article suggests completing the planning law with a suitable economic framework.

  10. Force approach to radiation reaction

    Energy Technology Data Exchange (ETDEWEB)

    López, Gustavo V., E-mail: gulopez@udgserv.cencar.udg.mx

    2016-02-15

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  11. Force approach to radiation reaction

    Science.gov (United States)

    López, Gustavo V.

    2016-02-01

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  12. Dispersion Forces

    CERN Document Server

    Buhmann, Stefan Yoshi

    2012-01-01

    In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of advanced aspects and scenarios. Macroscopic quantum electrodynamics is shown to provide a powerful framework for dispersion forces which allows for discussing general properties like their non-additivity and the relation between microscopic and macroscopic interactions. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. Starting with a brief recapitulation of volume I, this volume II deals especially with bodies of irregular shapes, universal scaling laws, dynamical forces on excited atoms, enhanced forces in cavity quantum electrodynamics, non-equilibrium forces in thermal environments and quantum friction. The book gives both the specialist and those new to the field a thorough overview over recent results in the field. It provides a toolbox for studying dispersion forces in various contex...

  13. Periodic behaviors

    CERN Document Server

    Napp, Diego; Shankar, Shiva

    2010-01-01

    This paper studies behaviors that are defined on a torus, or equivalently, behaviors defined in spaces of periodic functions, and establishes their basic properties analogous to classical results of Malgrange, Palamodov, Oberst et al. for behaviors on R^n. These properties - in particular the Nullstellensatz describing the Willems closure - are closely related to integral and rational points on affine algebraic varieties.

  14. PERIODIC BEHAVIORS

    NARCIS (Netherlands)

    Napp, Diego; Put, Marius van der; Shankar, Shiva

    2010-01-01

    This paper studies behaviors that are defined on a torus, or equivalently, behaviors defined in spaces of periodic functions, and establishes their basic properties analogous to classical results of Malgrange, Palamodov, Oberst et al. for behaviors on R(n). These properties-in particular the Nullste

  15. The destabilizing effect of external damping: Singular utter boundary for the Pfluger column with vanishing external dissipation

    CERN Document Server

    Tommasini, Mirko; Misseroni, Diego; Bigoni, Davide

    2016-01-01

    Elastic structures loaded by nonconservative positional forces are prone to instabilities induced by dissipation: it is well-known in fact that internal viscous damping destabilizes the marginally stable Ziegler's pendulum and Pfluger column (of which the Beck's column is a special case), two structures loaded by a tangential follower force. The result is the so-called 'destabilization paradox', where the critical force for flutter instability decreases by an order of magnitude when the coefficient of internal damping becomes infinitesimally small. Until now external damping, such as that related to air drag, is believed to provide only a stabilizing effect, as one would intuitively expect. Contrary to this belief, it will be shown that the effect of external damping is qualitatively the same as the effect of internal damping, yielding a pronounced destabilization paradox. Previous results relative to destabilization by external damping of the Ziegler's and Pfluger's elastic structures are corrected in a defi...

  16. External Measures of Cognition

    Directory of Open Access Journals (Sweden)

    Osvaldo eCairo

    2011-10-01

    Full Text Available The human brain is undoubtedly the most impressive, complex and intricate organ that has evolved over time. It is also probably the least understood, and for that reason, the one that is currently attracting the most attention. In fact, the number of comparative analyses that focus on the evolution of brain size in Homo sapiens and other species has increased dramatically in recent years. In neuroscience, no other issue has generated so much interest and been the topic of so many heated debates as the difference in brain size between socially defined population groups, both its connotations and implications. For over a century, external measures of cognition have been related to intelligence. However, it is still unclear whether these measures actually correspond to cognitive abilities. In summary, this paper must be reviewed with this premise in mind.

  17. Influence of the Basset force on the resonant behavior of an oscillator with fluctuating frequency

    Energy Technology Data Exchange (ETDEWEB)

    Rekker, A., E-mail: Astrid.Rekker@tlu.ee; Mankin, R., E-mail: Romi.Mankin@tlu.ee [Institute of Mathematics and Natural Sciences, Tallinn University, 29 Narva Road, 10120 Tallinn (Estonia)

    2015-10-28

    The influence of hydrodynamic interactions, such as Stokes and Basset forces, on the dynamics of a harmonically trapped Brownian tracer is considered. A generalized Langevin equation is used to describe the tracer’s response to an external periodic force and to dichotomous fluctuations of the stiffness of the trapping potential. Relying on the Shapiro-Loginov formula, exact expressions for the complex susceptibility and for the response function are presented. On the basis of these exact formulas, it is demonstrated that interplay of a multiplicative colored noise and the Basset force induced memory effects can generate a variety of cooperation effects, such as multiresonance versus the driving frequency, as well as stochastic resonance versus noise parameters. In particular, in certain parameter regions the response function exhibits a resonance-like enhancement at intermediate values of the intensity of the Basset force. Conditions for the appearance of these effects are also discussed.

  18. Magnus-induced dynamics of driven skyrmions on a quasi-one-dimensional periodic substrate

    Science.gov (United States)

    Reichhardt, C.; Reichhardt, C. J. Olson

    2016-09-01

    We numerically examine driven skyrmions interacting with a periodic quasi-one-dimensional substrate where the driving force is applied either parallel or perpendicular to the substrate periodicity direction. For perpendicular driving, the particles in a purely overdamped system simply slide along the substrate minima; however, for skyrmions where the Magnus force is relevant, we find that a rich variety of dynamics can arise. In the single skyrmion limit, the skyrmion motion is locked along the driving or longitudinal direction for low drives, while at higher drives a transition occurs to a state in which the skyrmion moves both transverse and longitudinal to the driving direction. Within the longitudinally locked phase we find a pronounced speedup effect that occurs when the Magnus force aligns with the external driving force, while at the transition to transverse and longitudinal motion, the skyrmion velocity drops, producing negative differential conductivity. For collectively interacting skyrmion assemblies, the speedup effect is still present and we observe a number of distinct dynamical phases, including a sliding smectic phase, a disordered or moving liquid phase, a moving hexatic phase, and a moving crystal phase. The transitions between the dynamic phases produce distinct features in the structure of the skyrmion lattice and in the velocity-force curves. We map these different phases as a function of the ratio of the Magnus term to the dissipative term, the substrate strength, the commensurability ratio, and the magnitude of the driving force.

  19. Capsules with external navigation and triggered release.

    Science.gov (United States)

    Shchukin, Dmitry G; Shchukina, Elena

    2014-10-01

    Encapsulation is an important technology for pharmaceutical industry, food production, et cetera. Its current level of development requires capsule functionalization. One of the interesting ideas to provide new functionality to the microcapsule and nanocapsule is layer-by-layer deposition of functional species. This technique provides step-by-step adsorption of various species (polyelectrolytes, nanoparticles, proteins) when the layer growth is controlled by electrostatic, hydrogen bonding, hydrophobic forces and forming multilayer shells with nanometer precision. This review article introduces recent achievements of layer-by-layer technique attaining external navigation ability and release properties the capsule shell.

  20. Excited and enhanced twinborn acoustic-induced mutual forces in oblique grating structures

    Science.gov (United States)

    Lu, Shuifang; Zhang, Xin; Wu, Fugen; Yao, Yuanwei; Chen, Zongwang

    2016-07-01

    We propose a water-immersed geometrically oblique grating structure patterned with a 1D periodic array of oblique rhombuses. Twin acoustic-induced mutual forces (both repulsive and attractive) between coupled steel plates were realized in this system when the external plane wave normally impacted the plates. Calculations showed that the emerging forces are more than an order of magnitude larger than the corresponding induced force of a conventional grating structure. We also found that the strong acoustic-induced mutual forces stem from the resonant excitation of nonleaky flexural Lamb modes in the coupled plates, and that these forces couple more strongly with the external incident acoustic waves. Furthermore, the amplitudes and resonant wavelengths of these forces can be coarsely controlled by changing the symmetry of the system and finely adjusted by varying the slant angle and the edge-length of the oblique rhombus. The proposed acoustic system could potentially be applied in sensors and in the ultrasonic detection of weak signals in water.

  1. Aberrant Force Processing in Schizophrenia.

    Science.gov (United States)

    Martinelli, Cristina; Rigoli, Francesco; Shergill, Sukhwinder S

    2016-07-06

    Initially considered as mere side effects of antipsychotic medication, there is now evidence that motor and somatosensory disturbances precede the onset of the illness and can be found in drug-naive patients. However, research on the topic is scarce. Here, we were interested in assessing the accuracy of the neural signal in detecting parametric variations of force linked to a voluntary motor act and a received tactile sensation, either self-generated or externally generated. Patients with a diagnosis of schizophrenia and healthy controls underwent functional magnetic resonance imaging while asked to press, or abstain from pressing, a lever in order to match a visual target force. Forces, exerted and received, varied on 10 levels from 0.5 N to 5 N in 0.5 N increments. Healthy participants revealed a positive correlation between force and activity in contralateral primary somatosensory area (S1) when performing a movement as well as when receiving a tactile sensation but only when this was externally, and not self-, generated. Patients showed evidence of altered force signaling in both motor and tactile conditions, as well as increased correlation with force when tactile sensation was self-generated. Findings are interpreted in line with accounts of predictive and sensory integration mechanisms and point toward alterations in the encoding of parametric forces in the motor and somatosensory domain in patients affected by schizophrenia.

  2. Impact of Learning Styles on Air Force Technical Training: Multiple and Linear Imagery in the Presentation of a Comparative Visual Location Task to Visual and Haptic Subjects. Interim Report for Period January 1977-January 1978.

    Science.gov (United States)

    Ausburn, Floyd B.

    A U.S. Air Force study was designed to develop instruction based on the supplantation theory, in which tasks are performed (supplanted) for individuals who are unable to perform them due to their cognitive style. The study examined the effects of linear and multiple imagery in presenting a task requiring visual comparison and location to…

  3. It's beyond my control: a cross-temporal meta-analysis of increasing externality in locus of control, 1960-2002.

    Science.gov (United States)

    Twenge, Jean M; Zhang, Liqing; Im, Charles

    2004-01-01

    Two meta-analyses found that young Americans increasingly believe their lives are controlled by outside forces rather than their own efforts. Locus of control scores became substantially more external (about.80 standard deviations) in college student and child samples between 1960 and 2002. The average college student in 2002 had a more external locus of control than 80% of college students in the early 1960s. Birth cohort/time period explains 14% of the variance in locus of control scores. The data included 97 samples of college students (n = 18,310) and 41 samples of children ages 9 to 14 (n = 6,554) gathered from dissertation research. The results are consistent with an alienation model positing increases in cynicism, individualism, and the self-serving bias. The implications are almost uniformly negative, as externality is correlated with poor school achievement, helplessness, ineffective stress management, decreased self-control, and depression.

  4. Stochastic Forcing for Ocean Uncertainty Prediction

    Science.gov (United States)

    2013-09-30

    shallow water waves governed by Korteweg-de Vries ( KdV ) dynamics with stochastic forcing. Uncertain Boundary Conditions and DO Equations: A...schemes to time-integrate shallow water surface waves governed by KdV equations with external stochastic forcing. We find that the DO scheme is

  5. About Radiation Reaction with Force Approach

    CERN Document Server

    Velazquez, Gustavo Lopez

    2015-01-01

    The difficulty of usual approach to radiation reaction is pointed out , and a possible approach based on the force acting to the charged particle which produces the acceleration itself, is presented. This approach brings about an expression such that acceleration is zero whenever the external force is zero.

  6. Entropic forces in Brownian motion

    CERN Document Server

    Roos, Nico

    2013-01-01

    The interest in the concept of entropic forces has risen considerably since E. Verlinde proposed to interpret the force in Newton s second law and Gravity as entropic forces. Brownian motion, the motion of a small particle (pollen) driven by random impulses from the surrounding molecules, may be the first example of a stochastic process in which such forces are expected to emerge. In this note it is shown that at least two types of entropic motion can be identified in the case of 3D Brownian motion (or random walk). This yields simple derivations of known results of Brownian motion, Hook s law and, applying an external (nonradial) force, Curie s law and the Langevin-Debye equation.

  7. Magnus force in superfluids and superconductors

    Science.gov (United States)

    Sonin, E. B.

    1997-01-01

    The forces on the vortex, transverse to its velocity, are considered. In addition to the superfluid Magnus force from the condensate (superfluid component), there are transverse forces from thermal quasiparticles and external fields violating the Galilean invariance. The forces between quasiparticles and the vortex originate from interference of quasiparticles with trajectories on the left and on the right from the vortex like similar forces for electrons interacting with the thin magnetic-flux tube (the Aharonov-Bohm effect). These forces are derived for phonons from the equations of superfluid hydrodynamics, and for BCS quasiparticles from the Bogolyubov-de Gennes equations. The effect of external fields breaking Galilean invariance is analyzed for vortices in the two-dimensional Josephson junction array. The symmetry analysis of the classical equations for the array shows that the total transverse force on the vortex vanishes. Therefore the Hall effect which is linear in the transverse force is absent also. This means that the Magnus force from the superfluid component exactly cancels with the transverse force from the external fields. The results of other approaches are also brought together for discussion.

  8. Sensitivity and chaos control for the forced nonlinear oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Bashkirtseva, Irina [Department of Mathematics, Ural State University, 620083 Ekaterinburg (Russian Federation); Ryashko, Lev [Department of Mathematics, Ural State University, 620083 Ekaterinburg (Russian Federation)] e-mail: lev.ryashko@usu.ru

    2005-12-01

    This paper is devoted to study the problem of controlling chaos for forced nonlinear dynamic systems. We suggest a new control technique based on sensitivity analysis. With the help of approximation of nonequilibrium quasipotential, stochastic sensitivity function (SSF) is constructed. This function is used as basic tool of a quantitative description for a system response on the random external disturbances. The possibilities of SSF to predict chaotic dynamics for the periodic and stochastic forced Brusselator are shown. The problem of chaos control based on SSF is considered. A design of attractors with the desired features by feedback regulator is discussed. Analysis of controllability and effective technique for regulator synthesis is presented. An example of suppressing chaos for Brusselator is considered.

  9. Climate forcings of past droughts in the Czech Lands

    Science.gov (United States)

    Mikšovský, Jiří; Trnka, Miroslav; Brázdil, Rudolf

    2015-04-01

    Frequency and intensity of local droughts is governed by a complex interaction of diverse processes, originating from internal dynamics of the climate system as well as its responses to external forcings. Separating and quantifying the effects of individual drought-inducing agents is a nontrivial task, often approached via statistical methods. In this presentation, we employ multiple linear regression to identify components attributable to various forcing factors, both external (solar irradiance, volcanic activity, anthropogenic greenhouse gases and aerosols) and internal (NAO, ENSO, AMO), in the monthly series of selected drought indices (PDSI, Z-index, SPI, SPEI) calculated for the territory of the recent Czech Republic during the 1883-2010 period. Moving block bootstrap is used for evaluation of the statistical significance of the results. Our analysis, carried out for drought index series characterizing a country-wide average as well as ten individual locations, suggests presence of a distinct component correlated with anthropogenic forcing (driven largely by the increasing concentrations of greenhouse gases) in the temperature-sensitive drought indices (PDSI, Z-index, SPEI). There are also indications of an influence of major volcanic eruptions in some of the Czech drought series, whereas variations of solar activity do not seem to leave a significant imprint. Of the major oscillatory modes in the climate system, North Atlantic Oscillation can be linked to a relatively strong component in most of the drought characteristics. Effects of ENSO, while generally weaker and scattered, are also detectable. No significant relation to Atlantic Multidecadal Oscillation phase was found.

  10. Thermodynamic characteristics of a Brownian heat pump in a spatially periodic temperature field

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper has studied the thermodynamic performance of a thermal Brownian heat pump,which consists of Brownian particles moving at a periodic sawtooth potential with external forces and contacting with the alternating hot and cold reservoirs along the space coordinate.The heat flows driven by both potential and kinetic energies are taken into account.The analytical expressions for the heating load,coefficient of performance(COP) and power input of the Brownian heat pump are derived and the performance characteristics are obtained by numerical calculations.It is shown that due to the heat flow via the change of kinetic energy of the particles,the Brownian heat pump is always irreversible and the COP can never attain the Carnot COP.The study has also investigated the influences of the operating parameters,i.e.the external force,barrier height of the potential,asymmetry of the sawtooth potential and temperature ratio of the heat reservoirs,on the performance of the Brownian heat pump.The effective regions of external force and barrier height of the potential in which the Brownian motor can operates as a heat pump are determined.The results show that the performance of the Brownian heat pump greatly depends on the parameters;if the parameters are properly chosen,the Brownian heat pump may be controlled to operate in the optimal regimes.

  11. Strong Force

    CERN Document Server

    Without the strong force, there could be no life. The carbon in living matter is synthesised in stars via the strong force. Lighter atomic nuclei become bound together in a process called nuclear fusion. A minor change in this interaction would make life impossible. As its name suggests, the strong force is the most powerful of the 4 forces, yet its sphere of influence is limited to within the atomic nucleus. Indeed it is the strong force that holds together the quarks inside the positively charged protons. Without this glue, the quarks would fly apart repulsed by electromagnetism. In fact, it is impossible to separate 2 quarks : so much energy is needed, that a second pair of quarks is produced. Text for the interactive: Can you pull apart the quarks inside a proton?

  12. The role of magnetoplasmons in Casimir force calculations

    CERN Document Server

    Esquivel-Sirvent, R; Palomino-Ovando, M A; Cocoletzi, G H

    2009-01-01

    In this paper we review the role of magneto plasmon polaritons in the Casimir force calculations. By applying an external constant magnetic field a strong optical anisotropy is induced on two parallel slabs reducing the reflectivity and thus the Casimir force. As the external magnetic field increases, the Casimir force decreases. Thus, with an an external magnetic field the Casimir force can be controlled.The calculations are done in the Voigt configuration where the magnetic field is parallel to the slabs. In this configuration the reflection coefficients for TE and TM modes do not show mode conversion.

  13. Attentional Focusing Instructions and Force Production

    Directory of Open Access Journals (Sweden)

    David C Marchant

    2011-01-01

    Full Text Available Research progress assessing the role of attentional focusing instructions on skill acquisition and performance has lead researchers to apply this approach to force production tasks. Initial converging evidence indicates that force production tasks are sensitive to verbal instruction; externally focused instructions (onto movement outcomes, or onto the object force is being exerted against are shown to be more beneficial than internally focused instructions (focusing attention onto the movements being executed. These benefits are observed for maximal and accurate force production, as well as the maintenance of force production in prolonged tasks. A range of mechanisms are identified supporting the proposal that an external focus promotes movement efficiency in line with energy and effort conservation. Future research is required to assess how this developing body of work interacts with the broader understanding of psychological and physiological factors implicated in the effective production, maintenance and limitation of maximal or sub-maximal forces.

  14. Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics

    Science.gov (United States)

    LaGraff, John E.; Povinelli, Louis A.; Gostelow, J. Paul; Glauser, Mark

    2010-01-01

    Topics covered include: Flow Physics and control for Internal and External Aerodynamics (not in TOC...starts on pg13); Breaking CFD Bottlenecks in Gas-Turbine Flow-Path Design; Streamwise Vortices on the Convex Surfaces of Circular Cylinders and Turbomachinery Blading; DNS and Embedded DNS as Tools for Investigating Unsteady Heat Transfer Phenomena in Turbines; Cavitation, Flow Structure and Turbulence in the Tip Region of a Rotor Blade; Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows; Active Flow Control of Lifting Surface With Flap-Current Activities and Future Directions; Closed-Loop Control of Vortex Formation in Separated Flows; Global Instability on Laminar Separation Bubbles-Revisited; Very Large-Scale Motions in Smooth and Rough Wall Boundary Layers; Instability of a Supersonic Boundary-Layer With Localized Roughness; Active Control of Open Cavities; Amplitude Scaling of Active Separation Control; U.S. Air Force Research Laboratory's Need for Flow Physics and Control With Applications Involving Aero-Optics and Weapon Bay Cavities; Some Issues Related to Integrating Active Flow Control With Flight Control; Active Flow Control Strategies Using Surface Pressure Measurements; Reduction of Unsteady Forcing in a Vaned, Contra-Rotating Transonic Turbine Configuration; Active Flow Control Stator With Coanda Surface; Controlling Separation in Turbomachines; Flow Control on Low-Pressure Turbine Airfoils Using Vortex Generator Jets; Reduced Order Modeling Incompressible Flows; Study and Control of Flow Past Disk, and Circular and Rectangular Cylinders Aligned in the Flow; Periodic Forcing of a Turbulent Axisymmetric Wake; Control of Vortex Breakdown in Critical Swirl Regime Using Azimuthal Forcing; External and Turbomachinery Flow Control Working Group; Boundary Layers, Transitions and Separation; Efficiency Considerations in Low Pressure Turbines; Summary of Conference; and Final Plenary Session

  15. Skepticism, contextualism, externalism and modality

    National Research Council Canada - National Science Library

    Ron Wilburn

    2006-01-01

    .... However, because efforts to contextualize externalism via subjunctive conditional analysis court circularity, it is only on an internalistic interpretation that contextualist strategies can even be motivated...

  16. External Influences on an Internal Process: Supporting Preservice Teacher Research

    Science.gov (United States)

    Schulte, Ann; Klipfel, Lyndsay Halpin

    2016-01-01

    In an effort to better understand how participating in teacher research as a student teacher compares to conducting it as a practicing teacher, a teacher educator and her former teacher education student engaged in a collaborative dialogue. They focus their reflections in this article on the impact of external forces on the process of teacher…

  17. Weak Force

    CERN Multimedia

    Without the weak force, the sun wouldn't shine. The weak force causes beta decay, a form of radioactivity that triggers nuclear fusion in the heart of the sun. The weak force is unlike other forces: it is characterised by disintegration. In beta decay, a down quark transforms into an up quark and an electron is emitted. Some materials are more radioactive than others because the delicate balance between the strong force and the weak force varies depending on the number of particles in the atomic nucleus. We live in the midst of a natural radioactive background that varies from region to region. For example, in Cornwall where there is a lot of granite, levels of background radiation are much higher than in the Geneva region. Text for the interactive: Move the Geiger counter to find out which samples are radioactive - you may be surprised. It is the weak force that is responsible for the Beta radioactivity here. The electrons emitted do not cross the plastic cover. Why do you think there is some detected radioa...

  18. Chemical reactions induced by oscillating external fields in weak thermal environments

    CERN Document Server

    Craven, Galen T; Hernandez, Rigoberto

    2015-01-01

    Chemical reaction rates must increasingly be determined in systems that evolve under the control of external stimuli. In these systems, when a reactant population is induced to cross an energy barrier through forcing from a temporally varying external field, the transition state that the reaction must pass through during the transformation from reactant to product is no longer a fixed geometric structure, but is instead time-dependent. For a periodically forced model reaction, we develop a recrossing-free dividing surface that is attached to a transition state trajectory [T. Bartsch, R. Hernandez, and T. Uzer, Phys. Rev. Lett. 95, 058301 (2005)]. We have previously shown that for single-mode sinusoidal driving, the stability of the time-varying transition state directly determines the reaction rate [G. T. Craven, T. Bartsch, and R. Hernandez, J. Chem. Phys. 141, 041106 (2014)]. Here, we extend our previous work to the case of multi-mode driving waveforms. Excellent agreement is observed between the rates pred...

  19. Stochastic resonance in the presence or absence of external signal in the continuous stirred tank reactor system

    Science.gov (United States)

    Hou, Zhonghuai; Xin, Houwen

    1999-07-01

    A two variable model, which has been proposed to describe a first-order, exothermic, irreversible reaction A→B carried out in a continuous stirred tank reactor (CSTR), is investigated when the control parameter is modulated by random and/or periodic forces. Within the bistable region where a limit cycle and a stable node coexist, stochastic resonance (SR) is observed when both random and periodic modulations are present. In the absence of periodic external signal noise induced coherent oscillations (NICO) appear when the control parameter is randomly modulated near the supercritical Hopf bifurcation point. In addition, the NICO-strength goes through a maximum with the increment of the noise intensity, characteristic for the occurrence of internal signal stochastic resonance (ISSR).

  20. Internal and forced climate variability during the last millennium: a model-data comparison using ensemble simulations

    Science.gov (United States)

    Goosse, Hugues; Renssen, Hans; Timmermann, Axel; Bradley, Raymond S.

    2005-07-01

    A three-dimensional climate model was used to perform 25 simulations over the last millennium, which are driven by the main natural and anthropogenic forcing. The results are compared to available reconstructions in order to evaluate the relative contribution of internal and forced variability during this period. At hemispheric and nearly hemispheric scale, the impact of the forcing is clear in all the simulations and knowing the forced response provides already a large amount of information about the behaviour of the climate system. Besides, at regional and local scales, the forcing has only a weak contribution to the simulated variability compared to internal variability. This result could be used to refine our conception of Medieval Warm Period and Little Ice Age (MWP and LIA). They were hemispheric-scale phenomena, since the temperature averaged over the Northern Hemisphere was, respectively generally higher/lower during those periods because of a stronger/weaker external forcing at that time. Nevertheless, at local-scale, the sign of the internal temperature variations determines to what extent the forced response will be actually visible or even masked by internal noise. Because of this role of internal variability, synchronous peak temperatures during the MWP or LIA between different locations are unlikely.

  1. An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios (External Review Draft)

    Science.gov (United States)

    EPA has released an external review draft entitled, An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios(External Review Draft). The public comment period and the external peer-review workshop are separate processes that provide opportunities ...

  2. Construction robot force control in cleaning operations

    Science.gov (United States)

    Zhou, Y.; Skibniewski, M. J.

    1994-01-01

    Basic surface treatment tasks on construction sites that can be performed by robots include the spraying, cleaning, and finishing of surfaces. In the present paper, a construction robot is proposed for accomplishing a variety of cleaning tasks in construction. Specifically, the force-control problem in cleaning a surface is studied. The paper shows that a force sensor can be used not only to monitor the force acting at the contact points, but also to identify the uncertainties of the unstructured construction environment. A different formulation for the external force is presented. With this formulation, the external force on the end-effector is presented as a function of the contact force, contact torque, and constraint conditions, but not the actuated torque in the joint space. Therefore, the force-control problem is simplified to compensate for the external force and to exert a desired force. One advantage fo this approach is that the original PID position control loop of an industrial robot is retained so that the time-consuming computed torque method is avoided. The proposed control scheme can be applied to numerous cleaning tasks with hard contact regardless of the different nature of the surface.

  3. Regulation of external LIF on the expression of integrin β3 in the mouse endo metrium during peri-implantation period%外源性LIF和IL-1对围着床期小鼠子宫内膜整合素β3亚基表达的调节

    Institute of Scientific and Technical Information of China (English)

    张炜; 周剑萍; 刘银坤; 朱瑾

    2001-01-01

    目的:研究外源性LIF及IL-1对围着床期子宫内膜整合素β 3表达的调节,探讨LIF参与着床的具体机制。方法:给孕2~4 d的小鼠注射不同浓度的白血病抑制因子、白介素- 1或白介素-1受体拮抗剂,应用免疫印迹法和RT-PCR法测定子宫内膜整合素β3的蛋白及 mRNA表达水平。结果:注射LIF、IL-1子宫内膜整合素β3的表达水平升高(P<0 . 05),且高剂量时升高更明显(P<0.01)。注射IL-1ra整合素β3水平下降(P<0 .05)。结论:细胞因子IL-1及LIF对围着床期子宫内膜表达整合素β3有促 调节作用,二者参与着床与调节细胞粘附分子表达有关。%Objective:To study regulation of external leukemia inhibitory factor(LIF) and interlukin- 1(IL-1) on the expression of integrin β3 in the mouse endometrium during per i-implantation period and explore the mechanism which LIF participate in embryo ni c implantation.Methods:The mice were injected peritoneally with LIF,IL-1 or IL-1ra at different administration on day 2~4 of pregnancy .The level of integrin β3 protein was measured with Westernblot method and mR NA measured with RT-PCR.Results:The levels of integrin β 3 protein and mRNA were increased by LIF and IL-1(P<0.05) and which reli ed o n administration.The level of integrin β3 mRNA was decreased by IL-1ra (P <0.05).Conclusion:LIF and IL-1 of cytokines can improve the expr ession of integrin β3 in the peri-implantation endometrium of mouse.Both of them may take part in implantation by regulating cell adhesion molecules.

  4. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summaris...... how the methodology has been applied so far in a previous Danish study. Finally, results of a case study are reported. Exposure factors have been calculated for various urban categories in the Greater Copenhagen Area...

  5. ExternE transport methodology for external cost evaluation of air pollution (DK)

    Energy Technology Data Exchange (ETDEWEB)

    Solvang Jensen, S.; Berkowicz, R.; Brandt, J. [National Environmental Research Inst., Dept. of Atmospheric Environment (Denmark); Willumsen, E.; Kristensen, N.B. [COWI (Denmark)

    2004-07-01

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AiGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Inititally, a brief description of the ExternE Transport methodology is given and it is summarised how the methodology has been applied so far in a previous Danish study. Finally, results of a case study are reported. Exposure factors have been calculated for various urban categories in the Greater Copenhagen Area. (au)

  6. External coating of colonic anastomoses

    DEFF Research Database (Denmark)

    Pommergaard, Hans-Christian; Achiam, Michael Patrick; Rosenberg, Jacob

    2012-01-01

    Colon anastomotic leakage remains both a frequent and serious complication in gastrointestinal surgery. External coating of colonic anastomoses has been proposed as a means to lower the rate of this complication. The aim of this review was to evaluate existing studies on external coating of colonic...

  7. Retrofitting Systems for External Walls

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report, 9 different external and internal retrofitting systems are analyzed using numerical calculations. The analysis focuses on the thermal bridge effects in the different systems, and on this basis it is discussed whether internal or external retrofitting has the most advantages...

  8. Buckling of elliptical rings under uniform external pressure

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Y.

    1991-04-03

    A thin, elastic elliptical ring is subjected to uniform external pressure. The lowest critical pressure is computed and presented for various ratio of the major axis to the minor axis of the elliptical ring. It is found that the critical pressure for an elliptical ring is higher than that for the circular ring whose diameter is equal to the major axis of the elliptical ring. It can be shown that under the same external pressure, the axial force developed in the elliptical ring is less than that developed in the corresponding circular ring. Thus, a higher pressure is required to buckle the elliptical rings. Therefore, by changing the shape of the ring from circular to elliptical, the capability of the ring to sustain the external pressure can be increased substantially. The results of this study can be useful in the design of elliptical reinforcing rings and thin-walled tubes subjected to external pressure.

  9. Performance Targets and External Benchmarking

    DEFF Research Database (Denmark)

    Friis, Ivar; Hansen, Allan; Vámosi, Tamás S.

    Research on relative performance measures, transfer pricing, beyond budgeting initiatives, target costing, piece rates systems and value based management has for decades underlined the importance of external benchmarking in performance management. Research conceptualises external benchmarking...... the conditions upon which the market mechanism is performing within organizations. This paper aims to contribute to research by providing more insight to the conditions for the use of external benchmarking as an element in performance management in organizations. Our study explores a particular type of external...... towards the conditions for the use of the external benchmarks we provide more insights to some of the issues and challenges that are related to using this mechanism for performance management and advance competitiveness in organizations....

  10. Photonic water dynamically responsive to external stimuli

    Science.gov (United States)

    Sano, Koki; Kim, Youn Soo; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Aida, Takuzo

    2016-08-01

    Fluids that contain ordered nanostructures with periodic distances in the visible-wavelength range, anomalously exhibit structural colours that can be rapidly modulated by external stimuli. Indeed, some fish can dynamically change colour by modulating the periodic distance of crystalline guanine sheets cofacially oriented in their fluid cytoplasm. Here we report that a dilute aqueous colloidal dispersion of negatively charged titanate nanosheets exhibits structural colours. In this `photonic water', the nanosheets spontaneously adopt a cofacial geometry with an ultralong periodic distance of up to 675 nm due to a strong electrostatic repulsion. Consequently, the photonic water can even reflect near-infrared light up to 1,750 nm. The structural colour becomes more vivid in a magnetic flux that induces monodomain structural ordering of the colloidal dispersion. The reflective colour of the photonic water can be modulated over the entire visible region in response to appropriate physical or chemical stimuli.

  11. External fixation in the treatment of open tibial shaft fractures

    Directory of Open Access Journals (Sweden)

    Golubović Zoran

    2008-01-01

    Full Text Available Background/Aim. Besides the conquasant fractures, open tibia shaft fractures belong to the group of the most severe fractures of tibia. Open tibia shaft fracture is one of the most common open fractures of long bones. They most frequently occur as a result of traffic accidents caused by the influence of a strong direct force. Methods. Within the period from January, 2000 to December 31, 2005. at the Clinic for Orthopaedics and Traumatology, Clinical Center Nis, 107 patients with open tibial fractures were treated. We analyzed 96 patients with open tibial fracture. In the series analyzed, the male sex was prevalent - there were 74 men (77.08%. The mean age was 47.3 years. The youngest patient was 17 years old, while the oldest patient was 79. According to the classification of the Gustilo et al. in the analysed group there were 30 (31.25% open tibial fractures of the I degree, 31 (32.29% of the II degree, 25 (26.05% of the III A degree, 8 (8.33% of the III B degree and 2 (2.08% of the III C degree. In 95 of the patients the treatment of open tibia shaft fractures consisted of the surgical treatment of wound and the external fixation of the fractured bone using "Mitkovic" type external fixator with a convergent method of pin applications. One primary amputations had been done in patients with grade IIIC open tibial fracture with large soft tissue defect. Results. Of the 96 open tibial fractures available for follow-up, 73 (76.04% healed without severe complications (osteitis, pseudoarthrosis, valgus malunion and amputation. Ther were nine (9.38% soft tissue pin track infections and six (6.25% superficial wound infections. The mean time of union was 21 (14-36 week. Among severe local complications associated with open tibial fractures, in eight patients (8.33% was registered osteitis, and in nine patients (9.38% fracture nonunion and the development of pseudoarthrosis. Three of the patients (3.13% had more than 10 degree valgus malunion. In one

  12. Cooperative behavior in periodically driven noisy integrate-fire models of neuronal dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bulsara, A.R. [Naval Command Control and Ocean Surveillance Center, Research, Development, Test, and Evaluation Division, Code 364, San Diego, California 92152-5000 (United States); Elston, T.C. [Center for Nonlinear Studies and Theoretical Division, MS-B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Doering, C.R. [Center for Nonlinear Studies and Theoretical Division, MS-B258, Los Alamos National Labortory, Los Alamos, New Mexico 87545 (United States); Lowen, S.B. [Electrical Engineering Department, Columbia University, New York, New York 10027 (United States); Lindenberg, K. [Department of Chemistry and Biochemistry B034, University of California at San Diego, La Jolla, California 92093-0340 (United States)

    1996-04-01

    The dynamics of the standard integrate-fire model and a simpler model (that reproduces the important features of the integrate-fire model under certain conditions) of neural dynamics are studied in the presence of a deterministic external driving force, taken to be time-periodic, and white background noise. Both models possess resonant phenomena in the first passage probability distribution and mean first passage time, arising from the interplay of characteristic time scales in the system. {copyright} {ital 1996 The American Physical Society.}

  13. External costs related to power production technologies. ExternE national implementation for Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Schleisner, L.; Sieverts Nielsen, P.

    1997-12-01

    The objective of the ExternE National Implementation project has been to establish a comprehensive and comparable set of data on externalities of power generation for all EU member states and Norway. The tasks include the application of the ExternE methodology to the most important fuel cycles for each country as well as to update the already existing results; to aggregate these site- and technology-specific results to more general figures. The current report covers the results of the national implementation for Denmark. Three different fuel cycles have been chosen as case studies. These are fuel cycles for an offshore wind farm and a wind farm on land, a decentralised CHP plant based on natural gas and a decentralised CHP plant based on biogas. The report covers all the details of the application of the methodology to these fuel cycles aggregation to a national level. (au) EU-JOULE 3. 59 tabs., 25 ills., 61 refs.

  14. Quantum Statistics of a Forced Oscillator with a Time-Dependent Driving Force

    Institute of Scientific and Technical Information of China (English)

    刘文森

    2003-01-01

    Quantum statistics of a forced harmonic oscillator acted upon by a time-dependent external force are derived using the Wilcox trick and the time-dependent inhomogeneous Bogoliubov transformation formalism.The internal energy,fluctuation of the particle-number average and entropy of this nonequilibrium system are presented explicitly.

  15. External fuel thermionic reactor system.

    Science.gov (United States)

    Mondt, J. F.; Peelgren, M. L.

    1971-01-01

    Thermionic reactors are prime candidates for nuclear electric propulsion. The national thermionic reactor effort is concentrated on the flashlight concept with the external-fuel concept as the backup. The external-fuel concept is very adaptable to a completely modular power subsystem which is attractive for highly reliable long-life applications. The 20- to 25-cm long, externally-fueled converters have been designed, fabricated, and successfully tested with many thermal cycles by electrical heating. However, difficulties have been encountered during encapsulation for nuclear heated tests and none have been started to date. These nuclear tests are required to demonstrate the concept feasibility.

  16. Nonlinear Dynamic Analysis of Coupled Gear-Rotor-Bearing System with the Effect of Internal and External Excitations

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shihua; SONG Guiqiu; REN Zhaohui; WEN Bangchun

    2016-01-01

    Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined internal and external excitations are scarcely investigated. An eight-degree-of-freedom(8-DOF) nonlinear spur gear-rotor-bearing model, which contains backlash, transmission error, eccentricity, gravity and input/output torque, is established, and the coupled lateral-torsional vibration characteristics are studied. Based on the equations of motion, the coupled spur gear-rotor-bearing system(SGRBS) is investigated using the Runge-Kutta numerical method, and the effects of rotational speed, error fluctuation and load fluctuation on the dynamic responses are explored. The results show that a diverse range of nonlinear dynamic characteristics such as periodic motion, quasi-periodic motion, chaotic behaviors and impacts exhibited in the system are strongly attributed to the interaction between internal and external excitations. Significantly, the changing rotational speed could effectively control the vibration of the system. Vibration level increases with the increasing error fluctuation. Whereas the load fluctuation has an influence on the nonlinear dynamic characteristics and the increasing excitation force amplitude makes the vibration amplitude increase, the chaotic motion may be restricted. The proposed model and numerical results can be used for diagnosis of faults and vibration control of practical SGRBS.

  17. Nonlinear dynamic analysis of coupled gear-rotor-bearing system with the effect of internal and external excitations

    Science.gov (United States)

    Zhou, Shihua; Song, Guiqiu; Ren, Zhaohui; Wen, Bangchun

    2016-03-01

    Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined internal and external excitations are scarcely investigated. An eight-degree-of-freedom(8-DOF) nonlinear spur gear-rotor-bearing model, which contains backlash, transmission error, eccentricity, gravity and input/output torque, is established, and the coupled lateral-torsional vibration characteristics are studied. Based on the equations of motion, the coupled spur gear-rotor-bearing system(SGRBS) is investigated using the Runge-Kutta numerical method, and the effects of rotational speed, error fluctuation and load fluctuation on the dynamic responses are explored. The results show that a diverse range of nonlinear dynamic characteristics such as periodic motion, quasi-periodic motion, chaotic behaviors and impacts exhibited in the system are strongly attributed to the interaction between internal and external excitations. Significantly, the changing rotational speed could effectively control the vibration of the system. Vibration level increases with the increasing error fluctuation. Whereas the load fluctuation has an influence on the nonlinear dynamic characteristics and the increasing excitation force amplitude makes the vibration amplitude increase, the chaotic motion may be restricted. The proposed model and numerical results can be used for diagnosis of faults and vibration control of practical SGRBS.

  18. Detecting an external influence on recent changes in oceanic oxygen using an optimal fingerprinting method

    OpenAIRE

    Andrews, O. D.; Bindoff, N. L.; P. R. Halloran; Ilyina, T.; Quéré, C.

    2013-01-01

    Ocean deoxygenation has been observed in all major ocean basins over the past 50 yr. Although this signal is largely consistent with oxygen changes expected from anthropogenic climate change, the contribution of external forcing to recent deoxygenation trends relative to natural internal variability is yet to be established. Here we conduct a formal optimal fingerprinting analysis to investigate if external forcing has had a detectable influence on observed dissolved oxygen ...

  19. Detecting an external influence on recent changes in oceanic oxygen using an optimal fingerprinting method

    OpenAIRE

    Andrews, O. D.; Bindoff, N. L.; P. R. Halloran; Ilyina, T.; Le Quéré, C.

    2012-01-01

    Ocean deoxygenation has been observed in all major ocean basins over the past 50 yr. Although this signal is largely consistent with oxygen changes expected from anthropogenic climate change, the contribution of external forcing to recent deoxygenation trends relative to natural internal variability is yet to be established. Here we conduct a formal optimal fingerprinting analysis to investigate if external forcing has had a detectable influence on observed dissolved oxygen concentration ([O&...

  20. Laurentide ice sheet dynamics during the last glacial period

    Science.gov (United States)

    Montoya, M.; Alvarez-Solas, J.; Robinson, A.; Banderas, R.

    2016-12-01

    Heinrich events (HEs) are interpreted as the result of massive large-scale ice discharges from the Laurentice ice sheet (LIS) into the North Atlantic that occurred during the Last Glacial Period (LGP). Classically they have been attributed to internal oscillations of the LIS, a mechanism that has been mimicked using three-dimensional ice-sheet models within the Shallow Ice Approximation (SIA) together with a modified basal sliding parameterisation accounting for enhanced ice-flow over a melting ice bed. However, recent studies using hybrid ice sheet-ice shelf models with more comprehensive dynamics combining the SIA and the Shallow Shelf Approximation (SSA) have proposed an alternative explanation involving the effects of oceanic circulation changes on the ice shelves. Up to now the plausibility of internal LIS instabilities in a hybrid ice sheet-ice shelf model combining SSA and SIA has seldom been investigated. Here we address this issue in the framework of the LGP by modifying the dynamics in a hybrid ice sheet-ice shelf model to mimick two different levels of complexity. We firstly suppress the binary mode mixture of sheet and stream ice in order to mimick the SIA, and include a basal sliding parameterisation. Under constant external climate forcing, quasi-periodic LIS instabilities are simulated in response to internal basal temperature oscillations. We then consider a more realistic dynamical formulation by incorporating the treatment of ice flow under the SSA. Internal basal temperature oscillations, and thereby LIS instabilities, are found to vanish under constant external forcing. Our results demonstrate how accounting for the longitudinal stresses of the ice streams, which is not possible within the pure SIA, is critical to stabilize ice flow and prevents the occurrence of the binge-purge oscillations.

  1. Intermolecular forces.

    Science.gov (United States)

    Buckingham, A D

    1975-11-06

    The nature of molecular interactions is examined. Intermolecular forces are divided into long-range and short-range components; the former operate at distances where the effects of electron exchange are negligible and decrease as an inverse power of the separation. The long-range interactions may be subdividied into electrostatic, induction and dispersion contributions, where the electrostatic component is the interaction of the permanent charge distributions and the others originate in the fluctuations in the distributions. Typical magnitudes of the various contributions are given. The forces between macroscopic bodies are briefly considered, as are the effects of a medium. Some of the manifestations of molecular interactions are discussed.

  2. Dynamical theory of active cellular response to external stress

    Science.gov (United States)

    de, Rumi; Safran, Samuel A.

    2008-09-01

    We present a comprehensive, theoretical treatment of the orientational response to external stress of active, contractile cells embedded in a gel-like elastic medium. The theory includes both the forces that arise from the deformation of the matrix as well as forces due to the internal regulation of the stress fibers and focal adhesions of the cell. We calculate the time-dependent response of both the magnitude and the direction of the elastic dipole that characterizes the active forces exerted by the cell, for various situations. For static or quasistatic external stress, cells orient parallel to the stress while for high frequency dynamic external stress, cells orient nearly perpendicular. Both numerical and analytical calculations of these effects are presented. In addition we predict the relaxation time for the cellular response for both slowly and rapidly varying external stresses; several characteristic scaling regimes for the relaxation time as a function of applied frequency are predicted. We also treat the case of cells for which the regulation of the stress fibers and focal adhesions is controlled by strain (instead of stress) and show that the predicted dependence of the cellular orientation on the Poisson ratio of the matrix can differentiate strain vs stress regulation of cellular response.

  3. Dynamical theory of active cellular response to external stress.

    Science.gov (United States)

    De, Rumi; Safran, Samuel A

    2008-09-01

    We present a comprehensive, theoretical treatment of the orientational response to external stress of active, contractile cells embedded in a gel-like elastic medium. The theory includes both the forces that arise from the deformation of the matrix as well as forces due to the internal regulation of the stress fibers and focal adhesions of the cell. We calculate the time-dependent response of both the magnitude and the direction of the elastic dipole that characterizes the active forces exerted by the cell, for various situations. For static or quasistatic external stress, cells orient parallel to the stress while for high frequency dynamic external stress, cells orient nearly perpendicular. Both numerical and analytical calculations of these effects are presented. In addition we predict the relaxation time for the cellular response for both slowly and rapidly varying external stresses; several characteristic scaling regimes for the relaxation time as a function of applied frequency are predicted. We also treat the case of cells for which the regulation of the stress fibers and focal adhesions is controlled by strain (instead of stress) and show that the predicted dependence of the cellular orientation on the Poisson ratio of the matrix can differentiate strain vs stress regulation of cellular response.

  4. Shear behavior of concrete beams externally prestressed with Parafil ropes

    Directory of Open Access Journals (Sweden)

    A.H. Ghallab

    2013-03-01

    Full Text Available Although extensive work has been carried out investigating the use of external prestressing system for flexural strengthening, a few studies regarding the shear behavior of externally prestressed beams can be found. Five beams, four of them were externally strengthened using Parafil rope, were loaded up to failure to investigate the effect of shear span/depth ratio, external prestressing force and concrete strength on their shear behavior. Test results showed that the shear span to depth ratio has a significant effect on both the shear strength and failure mode of the strengthened beams and the presence of external prestressing force increased the ultimate load of the tested beams by about 75%. Equations proposed by different codes for both the conventional reinforced concrete beams and for ordinary prestressed beams were used to evaluate the obtained experimental results. In general, codes equations showed a high level of conservatism in predicting the shear strength of the beams. Also, using the full strength rather than half of the concrete shear strength in the Egyptian code PC-method improves the accuracy of the calculated ultimate shear strength.

  5. Generation of homogeneous granular packings: Contact dynamics method with coupling to an external pressure bath

    CERN Document Server

    Shaebani, M Reza; Kertesz, Janos

    2008-01-01

    The contact dynamics method (CD) is an efficient simulation technique of dense granular media where unilateral and frictional contact problems for a large number of rigid bodies have to be solved. In this paper we present a modified version of the contact dynamics to generate homogeneous random packings of rigid grains. CD is coupled to an external pressure bath, which allows the variation of the size of a periodically repeated cell. We follow the concept of the Andersen dynamics and show how it can be applied within the framework of the contact dynamics method. The main challenge here is to handle the interparticle interactions properly, which are based on constraint forces in CD. We implement the proposed algorithm, perform test simulations and investigate the properties of the final packings.

  6. External costs related to power production technologies. ExternE national implementation for Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Schleisner, L.; Sieverts Nielsen, P. [eds.

    1997-12-01

    The objective of the ExternE National Implementation project has been to establish a comprehensive and comparable set of data on externalities of power generation for all EU member states and Norway. The tasks include the application of the ExternE methodology to the most important fuel cycles for each country as well as to update the already existing results, to aggregate these site- and technology-specific results to more general figures. The current report covers the detailed information concerning the ExternE methodology. Importance is attached to the computer system used in the project and the assessment of air pollution effects on health, materials and ecological effects. Also the assessment of global warming damages are described. Finally the report covers the detailed information concerning the national implementation for Denmark for an offshore wind farm and a wind farm on land, a decentralised CHP plant based on natural gas and a decentralised CHP plant base on biogas. (au) EU-JOULE 3. 79 tabs., 11 ills., 201 refs.

  7. Externality and burnout among dentists.

    Science.gov (United States)

    St-Yves, A; Freeston, M H; Godbout, F; Poulin, L; St-Amand, C; Verret, M

    1989-12-01

    This study investigates the relationship between burnout as measured by the Maslach Burnout Inventory and locus of control as measured by the Adult Nowicki-Strickland Internal-External Locus of Control (ANS-IE) for 82 dentists. Significant Pearson correlations between two Maslach subscales and locus of control show Personal Accomplishment to be negatively associated -.31 and Emotional Exhaustion to be positively correlated .21 to externality.

  8. Relatie interne en externe audit

    OpenAIRE

    Ghys, Emelie

    2011-01-01

    In het eerste hoofdstuk wordt de probleemstelling van deze eindverhandeling besproken. Interne en externe audit worden de laatste jaren internationaal en nationaal meer en meer erkend in het bedrijfsleven. Aanleiding voor de toenemende belangstelling van de interne en externe auditfunctie zijn de verschillende boekhoudschandalen rond corporate governance of deugdelijk bestuur. Deze financiële mislukkingen leidden wereldwijd tot diverse wetten, nieuwe regels en verbeterde standaarden om zo een...

  9. Performance Targets and External Benchmarking

    DEFF Research Database (Denmark)

    Friis, Ivar; Hansen, Allan; Vámosi, Tamás S.

    as a market mechanism that can be brought inside the firm to provide incentives for continuous improvement and the development of competitive advances. However, whereas extant research primarily has focused on the importance and effects of using external benchmarks, less attention has been directed towards...... towards the conditions for the use of the external benchmarks we provide more insights to some of the issues and challenges that are related to using this mechanism for performance management and advance competitiveness in organizations....

  10. Parallel External Memory Graph Algorithms

    DEFF Research Database (Denmark)

    Arge, Lars Allan; Goodrich, Michael T.; Sitchinava, Nodari

    2010-01-01

    In this paper, we study parallel I/O efficient graph algorithms in the Parallel External Memory (PEM) model, one o f the private-cache chip multiprocessor (CMP) models. We study the fundamental problem of list ranking which leads to efficient solutions to problems on trees, such as computing lowest...... an optimal speedup of ¿(P) in parallel I/O complexity and parallel computation time, compared to the single-processor external memory counterparts....

  11. Possible External Forcing Factors for the Interdecadal Change in the East Asian Winter Monsoon around the Late 1990s%20世纪90年代末东亚冬季风年代际变化的外强迫因子分析

    Institute of Scientific and Technical Information of China (English)

    肖晓; 陈文; 范广洲; 周定文

    2016-01-01

    In this study, the authors investigate the effects of anomalous sea surface temperature (SST), sea ice, and snow cover in the interdecadal change in the East Asian Winter Monsoon (EAWM) that occurred around the late 1990s by using reanalysis datasets from NCEP/NCAR, the Met Office Hadley Centre, the NOAA Climate Diagnostic Center, and the Northern Hemisphere snow cover reanalysis product from NOAA. Characteristics of and mechanisms for the interdecadal changes in the EAWM that occurred around mid-1980s (1976−1988) and late 1990s (1999−2012) are also compared. Results indicate that the interdecadal change in the EAWM that occurred around mid-1980s is characterized by negative temperature anomalies over the entire areas of China. The interdecadal change in the EAWM that occurred around mid-1980s is not related to external forcing including SST and sea ice anomalies. Instead, it is attributed to internal atmospheric dynamics. However, the interdecadal change in the EAWM that occurred around the late 1990s may be attributed to external forcing of SST, sea ice and snow cover anomalies in the preceding fall and winter. Particularly, the warmer SST in the late 1990s over the North Atlantic triggered an atmospheric wave train that propagated eastward and reached East Asia. This wave train intensified Siberian high, leading to a stronger EAWM and negative temperature anomalies over northern East Asia. The reduced sea ice anomalies in the Arctic Ocean and the increased snow cover over the Eurasian Continent in the preceding autumn is also a possible reason for the interdecadal change in the EAWM occurred around the late 1990s. In addition, positive SST anomalies over the tropical western Pacific can lead to convergence and enhanced convection over the maritime continent. As a result, cyclonic circulation anomalies over the tropical eastern Indian Ocean developed via a Gill type response. The anomalous southerly winds to the east of the cyclone eventually led to positive

  12. Force-Mediated Kinetics of Single P-Selectin/Ligand Complexes Observed by Atomic Force Microscopy

    Science.gov (United States)

    Fritz, Jurgen; Katopodis, Andreas G.; Kolbinger, Frank; Anselmetti, Dario

    1998-10-01

    Leukocytes roll along the endothelium of postcapillary venules in response to inflammatory signals. Rolling under the hydrodynamic drag forces of blood flow is mediated by the interaction between selectins and their ligands across the leukocyte and endothelial cell surfaces. Here we present force-spectroscopy experiments on single complexes of P-selectin and P-selectin glycoprotein ligand-1 by atomic force microscopy to determine the intrinsic molecular properties of this dynamic adhesion process. By modeling intermolecular and intramolecular forces as well as the adhesion probability in atomic force microscopy experiments we gain information on rupture forces, elasticity, and kinetics of the P-selectin/P-selectin glycoprotein ligand-1 interaction. The complexes are able to withstand forces up to 165 pN and show a chain-like elasticity with a molecular spring constant of 5.3 pN nm-1 and a persistence length of 0.35 nm. The dissociation constant (off-rate) varies over three orders of magnitude from 0.02 s-1 under zero force up to 15 s-1 under external applied forces. Rupture force and lifetime of the complexes are not constant, but directly depend on the applied force per unit time, which is a product of the intrinsic molecular elasticity and the external pulling velocity. The high strength of binding combined with force-dependent rate constants and high molecular elasticity are tailored to support physiological leukocyte rolling.

  13. Passive microrheology of soft materials with atomic force microscopy: A wavelet-based spectral analysis

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Torres, C.; Streppa, L. [CNRS, UMR5672, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, 46 Allée d' Italie, Université de Lyon, 69007 Lyon (France); Arneodo, A.; Argoul, F. [CNRS, UMR5672, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, 46 Allée d' Italie, Université de Lyon, 69007 Lyon (France); CNRS, UMR5798, Laboratoire Ondes et Matière d' Aquitaine, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence (France); Argoul, P. [Université Paris-Est, Ecole des Ponts ParisTech, SDOA, MAST, IFSTTAR, 14-20 Bd Newton, Cité Descartes, 77420 Champs sur Marne (France)

    2016-01-18

    Compared to active microrheology where a known force or modulation is periodically imposed to a soft material, passive microrheology relies on the spectral analysis of the spontaneous motion of tracers inherent or external to the material. Passive microrheology studies of soft or living materials with atomic force microscopy (AFM) cantilever tips are rather rare because, in the spectral densities, the rheological response of the materials is hardly distinguishable from other sources of random or periodic perturbations. To circumvent this difficulty, we propose here a wavelet-based decomposition of AFM cantilever tip fluctuations and we show that when applying this multi-scale method to soft polymer layers and to living myoblasts, the structural damping exponents of these soft materials can be retrieved.

  14. Comportamento da força de desprendimento dos frutos de cafeeiros ao longo do período de colheita Behavior of the coffee fruit detachment force throughout the harvest period

    Directory of Open Access Journals (Sweden)

    Flávio Castro da Silva

    2010-04-01

    operating speed. A possible objective parameter can be the detachment force of coffee fruits. For this determination it was necessary to develop and produce a portable dynamometer for the collection of data from the field. Its production and calibration were completed in the calibration and laboratory prototypes of the Department of Engineering at UFLA. Tests of detachment force fruit were made in Capetinga farm in the municipality of Boa Esperança in the 2006/2007 season. The cultivars used in the were: Mundo Novo IAC 376/4, Catuai amarelo IAC 99 and Icatu IAC 3282, transplanted in spacing 4.0 x 1.0 m with average population of 2.5 thousand plants per 10.000 m². The tests were conducted with three replicates using the completely randomized design (DIC in the same soil, in random parcels containing five plants. The aim was to raise the detachment force of the coffee fruits in the plant according to fruit maturation, being ranked for the determination of force: the green fruit, cherry, passes and dry. It was concluded that there are significant differences between stages of maturity among the cultivars and progenies evaluated. Cultivars Mundo Novo and Catuai presented smaller average values of strength of detachment. It was possible to correlate the strength of fruit detachment to determine the degree of maturation of the culture, since it is an objective parameter.

  15. Timing is everything: coordination of strike kinematics affects the force exerted by suction feeding fish on attached prey.

    Science.gov (United States)

    Holzman, Roi; Day, Steven W; Wainwright, Peter C

    2007-10-01

    During aquatic suction feeding, the predator opens its mouth and rapidly expands its buccal cavity, generating a flow field external to the mouth. The rapid expansion of the buccal cavity produces high fluid velocities and accelerations that extend only a short distance from the mouth (about half of one mouth diameter), and only persist for several milliseconds. Therefore, the predator must precisely time its strike to locate the prey within the narrow region of high flow, during the brief period when flow is at its peak. With flow being the agent for transferring force to the prey, the predator may enhance these forces by producing higher water velocities and faster acceleration at the mouth, but also through increasing the strike's accuracy, i.e. locating the prey closer to the mouth at the instant of peak flow speed. The objectives of this study were to directly measure forces exerted by bluegill Lepomis macrochirus on their prey and to determine how bluegill modify force output. Bluegill were offered ghost shrimp tethered to a load cell that recorded force at 5000 Hz, and feeding sequences were synchronously recorded using 500 Hz video. Peak forces exerted on attached 20 mm shrimp ranged from 0.005 N to 0.506 N. In accordance with the short duration of the strikes (average time to peak gape of approximately 13 ms), the forces recorded were brief (approximately 12 ms from initiation to peak force), and force magnitude declined rapidly after peak force. Statistical analysis indicated that rate of buccal expansion, and prey size, but not strike initiation distance, significantly affected peak force. These observed variables were used with results from flow visualization studies to estimate the flow at the prey's location, which allowed the calculation of drag, pressure gradient force and acceleration reaction force. The relationship between these calculated forces and the measured forces was strong, indicating that the model can be used to estimate forces from

  16. External Costs Related to Power Production Technologies

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1997-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  17. External Costs Related to Power Production Technologies

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1997-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective of...

  18. Axial force measurement for esophageal function testing

    DEFF Research Database (Denmark)

    Gravesen, Flemming Holbæk; Funch-Jensen, Peter; Gregersen, Hans

    2009-01-01

    force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been...... force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external...... documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe...

  19. DNA under Force: Mechanics, Electrostatics, and Hydration

    Directory of Open Access Journals (Sweden)

    Jingqiang Li

    2015-02-01

    Full Text Available Quantifying the basic intra- and inter-molecular forces of DNA has helped us to better understand and further predict the behavior of DNA. Single molecule technique elucidates the mechanics of DNA under applied external forces, sometimes under extreme forces. On the other hand, ensemble studies of DNA molecular force allow us to extend our understanding of DNA molecules under other forces such as electrostatic and hydration forces. Using a variety of techniques, we can have a comprehensive understanding of DNA molecular forces, which is crucial in unraveling the complex DNA functions in living cells as well as in designing a system that utilizes the unique properties of DNA in nanotechnology.

  20. Identifying external influences on global precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Marvel, K.; Bonfils, C.

    2013-11-11

    Changes in global (ocean and land) precipitation are among the most important and least well-understood consequences of climate change. Increasing greenhouse gas concentrations are thought to affect the zonal-mean distribution of precipitation through two basic mechanisms. First, increasing temperatures will lead to an intensification of the hydrological cycle (“thermodynamic” changes). Second, changes in atmospheric circulation patterns will lead to poleward displacement of the storm tracks and subtropical dry zones and to a widening of the tropical belt (“dynamic” changes). We demonstrate that both these changes are occurring simultaneously in global precipitation, that this behavior cannot be explained by internal variability alone, and that external influences are responsible for the observed precipitation changes. Whereas existing model experiments are not of sufficient length to differentiate between natural and anthropogenic forcing terms at the 95% confidence level, we present evidence that the observed trends result from human activities.

  1. Force decomposition in robot force control

    Science.gov (United States)

    Murphy, Steve H.; Wen, John T.

    1991-01-01

    The unit inconsistency in force decomposition has motivated an investigation into the force control problem in multiple-arm manipulation. Based on physical considerations, it is argued that the force that should be controlled is the internal force at the specified frame in the payload. This force contains contributions due to both applied forces from the arms and the inertial force from the payload and the arms. A least-squares scheme free of unit inconsistency for finding this internal force is presented. The force control issue is analyzed, and an integral force feedback controller is proposed.

  2. Heat Conductivity of One-Dimensional Carbon Chain in an External Potential

    Institute of Scientific and Technical Information of China (English)

    GE Yong; DONG Jin-Ming

    2007-01-01

    The heat transport in a one-dimensional (1D) carbon nanowire (CNW) lying in an external potential with different amplitudes and periods is studied by the non-equilibrium molecular dynamics method. It is found that the thermal conductivity of CNW is always anomalous, increasing with the CNW length and obeying the power law κ~ N, in which α decreases with the increasing external potential amplitude. The thermal conductivity could be enhanced by the external potential with rather larger amplitudes, which means that an applied external potential could be an efficient tool to improve the heat conductivity of a real 1D material. In addition, the effect of different periods of the external potential is studied, finding the external potential with an incommensurate period leads to the smaller α value.

  3. Quantized transport for a skyrmion moving on a two-dimensional periodic substrate

    Science.gov (United States)

    Reichhardt, C.; Ray, D.; Reichhardt, C. J. Olson

    2015-03-01

    We examine the dynamics of a skyrmion moving over a two-dimensional periodic substrate utilizing simulations of a particle-based skyrmion model. We specifically examine the role of the nondissipative Magnus term on the driven motion and the resulting skyrmion velocity-force curves. In the overdamped limit, there is a depinning transition into a sliding state in which the skyrmion moves in the same direction as the external drive. When there is a finite Magnus component in the equation of motion, a skyrmion in the absence of a substrate moves at an angle with respect to the direction of the external driving force. When a periodic substrate is added, the direction of motion or Hall angle of the skyrmion is dependent on the amplitude of the external drive, only approaching the substrate-free limit for higher drives. Due to the underlying symmetry of the substrate the direction of skyrmion motion does not change continuously as a function of drive, but rather forms a series of discrete steps corresponding to integer or rational ratios of the velocity components perpendicular ( ) and parallel ( ) to the external drive direction: / =n /m , where n and m are integers. The skyrmion passes through a series of directional locking phases in which the motion is locked to certain symmetry directions of the substrate for fixed intervals of the drive amplitude. Within a given directionally locked phase, the Hall angle remains constant and the skyrmion moves in an orderly fashion through the sample. Signatures of the transitions into and out of these locked phases take the form of pronounced cusps in the skyrmion velocity versus force curves, as well as regions of negative differential mobility in which the net skyrmion velocity decreases with increasing external driving force. The number of steps in the transport curve increases when the relative strength of the Magnus term is increased. We also observe an overshoot phenomena in the directional locking, where the skyrmion motion

  4. China's Economy Enters Key Period of Softlanding

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ China's economy is now at a key period for softlanding in light of growing investment, the driving force of its fast economic expansion,according to a report by a task force for the State Development and Reform Commission(SDRC).

  5. China's Economy Enters Key Period of Softlanding

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

      China's economy is now at a key period for softlanding in light of growing investment, the driving force of its fast economic expansion,according to a report by a task force for the State Development and Reform Commission(SDRC).……

  6. Electric charges and forces in atomic force microscopy and nano-xerography

    Energy Technology Data Exchange (ETDEWEB)

    Stemmer, A; Ziegler, D; Seemann, L; Naujoks, N [Nanotechnology Group, ETH Zurich, Tannenstrasse 3, 8092 Zurich (Switzerland); Rychen, J [Nanonis GmbH, Technoparkstrasse 1, 8005 Zurich (Switzerland)], E-mail: astemmer@ethz.ch

    2008-12-01

    Electrostatic forces generated by contact potential differences, localized charges, or externally applied voltages play a crucial role in atomic force microscopy. Electrostatic forces mediate the non-contact measurement of local potentials by the Kelvin probe technique, enabling compositional mapping of surfaces. However, if not compensated properly, electrostatic forces lead to height errors in topography images acquired in tapping mode. We present a single scan Kelvin probe force microscopy technique that compensates local electrostatic forces and allows simultaneous height and potential measurements in tapping mode. Electrostatic forces also direct the localized assembly of structures in nano-xerography. Here we describe how positive charges, written into a thin film of poly(methyl)methacrylate with the conductive tip of an atomic force microscope, guide the deposition of carboxyl-functionalized multiwalled carbon nanotubes suspended in isopropyl-alcohol.

  7. Interpretation and preliminary simulation of the 40 ka periodicity of the Quaternary glaciation

    Institute of Scientific and Technical Information of China (English)

    LI Nan; CHEN Xing

    2007-01-01

    More and more proxy records approved that the periodicity of the glacial cycles is about 40 ka before MPT (middle Pleistocene transition) as early as late Tertiary from 3.0 Ma to 0.9 Ma, whereas it changes to about 100 ka after MPT.Summer insolation at high latitude in Northern Hemisphere, usually considered as the main external force for the ice age, is dominated by the 23 ka precession period, which does not match the period of the glacial cycles.In this paper, we define an energy index C and its threshold Ct that indicate the net energy supply and the overall response of the climate system.The difference between these two parameters determines whether the ice sheet melts or not, and accordingly the start and termination of the interglacial stages, as well as the periodicity of glacial oscillations.Based on the energy threshold hypothesis, the preliminary simulation experiments are made to test the period of the glacial cycles and driven factors from a conceptual model.The results indicate that energy index C and threshold Ct can interpret not only the 40 ka periodicity before MPT, but also the quasi-100 ka periodicity after MPT to some extent, and the 40 ka is the basic period of the glacial cycles, which discloses the inherent continuity of climatic change before and after MPT.

  8. A regional climate palaeosimulation for Europe in the period 1500–1990 – Part 1: Model validation

    Directory of Open Access Journals (Sweden)

    J. J. Gómez-Navarro

    2013-04-01

    Full Text Available We present and analyse a high-resolution regional climate palaeosimulation encompassing the European region for the period 1500–1990. We use the regional model MM5 coupled to the global model ECHO-G. Both models were driven by reconstructions of three external factors: greenhouse gas concentrations, Total Solar Irradiance and volcanic activity. The simulation has been assessed in a recent period by comparing the model results with the Climate Research Unit (CRU database. The results show that although the regional model is tightly driven by the boundary conditions, it is able to improve the reliability of the simulations, narrowing the differences to the observations, especially in areas of complex topography. Additionally, the evolution of the spatial distributions of temperature and precipitation through the last five centuries has been analysed. The mean values of temperature reflects the influence of the external forcings but, contrary to the results obtained under climate change scenario conditions, we found that higher-order momenta of the probability distribution of seasonal temperature and precipitation are hardly affected by changes in the external forcings

  9. Leveraging External Sources of Innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2014-01-01

    This paper reviews research on open innovation that considers how and why firms commercialize external sources of innovations. It examines both the “outside-in” and “coupled” modes of open innovation. From an analysis of prior research on how firms leverage external sources of innovation...... cited work beyond those journals. A review of 291 open innovation-related publications from these sources shows that the majority of these articles indeed address elements of this inbound open innovation process model. Specifically, it finds that researchers have front-loaded their examination...... external innovations create value rather than how firms capture value from those innovations. Finally, the interaction phase considers both feedback for the linear process and reciprocal innovation processes such as cocreation, network collaboration, and community innovation. This review and synthesis...

  10. Quasistatic Modeling of Concentric Tube Robots with External Loads.

    Science.gov (United States)

    Lock, Jesse; Laing, Genevieve; Mahvash, Mohsen; Dupont, Pierre E

    2010-12-03

    Concentric tube robots are a subset of continuum robots constructed by combining pre-curved elastic tubes. As the tubes are rotated and translated with respect to each other, their curvatures interact elastically, enabling control of the robot's tip configuration as well as the curvature along its length. This technology is projected to be useful in many types of minimally invasive medical procedures. Because these robots are flexible by design, they deflect considerably when applying forces to the external environment. Thus, in contrast to rigid-link robots, their kinematic and static force models are coupled. This paper derives a multi-tube quasistatic model that relates tube rotations and translations together with externally applied loads to robot shape and tip configuration. The model can be applied in robot design, procedure planning as well as control. For validation, the multi-tube model is compared experimentally to a computationally-efficient single-tube approximate model.

  11. Thermodynamic Branch in the Chemical System Response to External Impact

    CERN Document Server

    Zilbergleyt, B

    2012-01-01

    The paper gives an account of a detailed investigation of the thermodynamic branch as a path of the chemical system deviation from its isolated thermodynamic equilibrium under an external impact. For a combination of direct and reverse reactions in the same chemical system, full thermodynamic branch is presented by an S-shaped curve, whose ends asymptotically achieve appropriate initial states, which, in turn, are logistic ends of the opposite reactions. The slope tangents of the steepest parts of the curves, the areas of the maximum rate of the shift growth vs. the external thermodynamic force, occurred to be directly proportional to the force and, simultaneously, linearly proportional to the thermodynamic equivalent of chemical reaction, which is the ratio between the amount in moles of any reaction participant, transformed in an isolated system, along the reaction way from its initial state to thermodynamic equilibrium, to its stoichiometric coefficient. The found linearity is valid for arbitrary combinati...

  12. Relação entre a pressão muscular perineal no puerpério e o tipo de parto Relationship between perineal muscular force in the puerperal period and the type of delivery

    Directory of Open Access Journals (Sweden)

    Silmara Menta

    2006-09-01

    Full Text Available OBJETIVO: relacionar o tipo de parto e as características do períneo com valores da pressão muscular perineal (PMP mensurada em primíparas nas posições deitada e sentada com a musculatura perineal em repouso e em contração máxima. MÉTODOS: estudo quantitativo do tipo transversal, realizado em maternidade conveniada ao Sistema Único de Saúde (SUS do município de São Paulo. A casuística, obtida por conveniência, foi de 95 primíparas de termo. A avaliação ocorreu entre o 40º e o 45º dia. Realizaram-se entrevista, exame físico e mensuração da PMP por meio do perineômetro de Kegel. A mensuração foi realizada nas posições deitada e sentada, com a musculatura em repouso e em contração máxima, sendo considerada a média de três aferições para cada posição e estado muscular. RESULTADOS: 76,8% (73 das primíparas tiveram parto vaginal e 23,2% (22 cesárea. No pós-parto vaginal, observou-se períneo íntegro em 18,9% (18, com rotura perineal em 24,2% (23 e com episiotomia em 33,7% (32. Os valores obtidos da PMP foram em: posição deitada/musculatura em repouso, 18,9 mmHg; deitada/musculatura em contração máxima, 30,7 mmHg; sentada/musculatura em repouso, 34,5 mmHg; sentada/musculatura em contração máxima, 46,5 mmHg. CONCLUSÃO: não houve associação entre o tipo de parto e as condições perineais e a pressão muscular perineal.PURPOSE: to determine the values of perineal muscular force (PMF in the lying and seated positions and to identify the values of PMF between first pregnancy, according to type and the characteristics of the vaginal delivery and cesarean section. METHODS: study of the transversal type, performed in a maternity of Brazilian Public the Health System (SUS in the city of São Paulo. The sample consisted of 95 primiparae at term. Evaluation occurred between the 40th and 45 th, day with an interview, physical examination and measurement of PMF using a perineometer of the Kegel type. The

  13. Ship emissions and their externalities for Greece

    Science.gov (United States)

    Tzannatos, Ernestos

    2010-06-01

    The existing and emerging international and European policy framework for the reduction of ship exhaust emissions dictates the need to produce reliable national, regional and global inventories in order to monitor emission trends and consequently provide the necessary support for future policy making. Furthermore, the inventories of ship exhaust emissions constitute the basis upon which their external costs are estimated in an attempt to highlight the economic burden they impose upon the society and facilitate the cost-benefit analysis of the proposed emission abatement technologies, operational measures and market-based instruments prior to their implementation. The case of Greece is of particular interest mainly because the dense ship traffic within the Greek seas directly imposes the impact of its exhaust emission pollutants (NO x, SO 2 and PM) upon the highly populated, physically sensitive and culturally precious Greek coastline, as well as upon the land and seas of Greece in general, whereas the contribution of Greece in the global CO 2 inventory at a time of climatic change awareness cannot be ignored. In this context, this paper presents the contribution of Greece in ship exhaust emissions of CO 2, NO x, SO 2 and PM from domestic and international shipping over the last 25 years (1984-2008), utilizing the fuel-based (fuel sales) emission methodology. Furthermore, the ship exhaust emissions generated within the Greek seas and their externalities are estimated for the year 2008, through utilizing the fuel-based (fuel sales) approach for domestic shipping and the activity-based (ship traffic) approach for international shipping. On this basis, it was found that during the 1984 to 2008 period the fuel-based (fuel sales) ship emission inventory for Greece increased at an average annual rate of 2.85%. In 2008, the CO 2, NO x, SO 2 and PM emissions reached 12.9 million tons (of which 12.4 million tons of CO 2) and their externalities were found to be around 3

  14. Labour force participation and the feminising of the labour force

    OpenAIRE

    Brendan M. Walsh

    1992-01-01

    This paper studies the effects of changes in labour force particiapation rates on the size and structure of the Irish labour force over the period 1971-1991. The rise in participation rates among females aged 25-54 and the decline in participation among older and younger people of both sexes altered the structure of the labour force significantly. Time series of annual participation rates are used to explore the reasons for these changes. It is shown that participation rates among those aged ...

  15. External rib structure can be predicted using mathematical models: An anatomical study with application to understanding fractures and intercostal muscle function.

    Science.gov (United States)

    Casha, Aaron R; Camilleri, Liberato; Manché, Alexander; Gatt, Ruben; Attard, Daphne; Gauci, Marilyn; Camilleri-Podesta, Marie-Therese; Grima, Joseph N

    2015-05-01

    As ribs adapt to stress like all bones, and the chest behaves as a pressure vessel, the effect of stress on the ribs can be determined by measuring rib height and thickness. Rib height and thickness (depth) were measured using CT scans of seven rib cages from anonymized cadavers. A Finite Element Analysis (FEA) model of a rib cage was constructed using a validated approach and used to calculate intramuscular forces as the vectors of both circumferential and axial chest wall forces at right angles to the ribs. Nonlinear quadratic models were used to relate rib height and rib thickness to rib level, and intercostal muscle force to vector stress. Intercostal muscle force was also related to vector stress using Pearson correlation. For comparison, rib height and thickness were measured on CT scans of children. Rib height increased with rib level, increasing by 13% between the 3rd and 7th rib levels, where the 7th/8th rib was the widest part or "equator" of the rib cage, P Intercostal muscle force was significantly related to vector stress, Pearson correlation r = 0.944, P = 0.005. The three nonlinear quadratic models developed all had statistically significant parameter estimates with P intercostal muscle force, showing that environmental factors affect external rib morphology. © 2015 Wiley Periodicals, Inc.

  16. A recurrence network approach to analyzing forced synchronization in hydrodynamic systems

    Science.gov (United States)

    Murugesan, Meenatchidevi; Zhu, Yuanhang; Li, Larry K. B.

    2016-11-01

    Hydrodynamically self-excited systems can lock into external forcing, but their lock-in boundaries and the specific bifurcations through which they lock in can be difficult to detect. We propose using recurrence networks to analyze forced synchronization in a hydrodynamic system: a low-density jet. We find that as the jet bifurcates from periodicity (unforced) to quasiperiodicity (weak forcing) and then to lock-in (strong forcing), its recurrence network changes from a regular distribution of links between nodes (unforced) to a disordered topology (weak forcing) and then to a regular distribution again at lock-in (strong forcing). The emergence of order at lock-in can be either smooth or abrupt depending on the specific lock-in route taken. Furthermore, we find that before lock-in, the probability distribution of links in the network is a function of the characteristic scales of the system, which can be quantified with network measures and used to estimate the proximity to the lock-in boundaries. This study shows that recurrence networks can be used (i) to detect lock-in, (ii) to distinguish between different routes to lock-in, and (iii) as an early warning indicator of the proximity of a system to its lock-in boundaries. This work was supported by the Research Grants Council of Hong Kong (Project No. 16235716 and 26202815).

  17. Optimal Auctions with Financial Externalities

    NARCIS (Netherlands)

    Maasland, E.; Onderstal, A.M.

    2002-01-01

    We construct optimal auctions when bidders face financial externalities.In a Coasean World, in which the seller cannot prevent a perfect resale market, nor withhold the object, the lowest-price all-pay auction is optimal.In a Myersonean World, in which the seller can both prevent resale after the au

  18. Organizing for External Knowledge Sourcing

    DEFF Research Database (Denmark)

    Rabbiosi, Larissa; Reichstein, Toke

    2011-01-01

    The aim of this article is to provide an introduction to the special issue. We briefly consider the external knowledge sourcing and organizing for innovation literatures, which offer a background for the special issue, and we highlight their mutual dialogue. We then illustrate the main findings...

  19. Measuring Externalities in Program Evaluation

    NARCIS (Netherlands)

    Janssens, Wendy

    2005-01-01

    Impact evaluations of development programmes usually focus on a comparison of participants with a control group. However, if the programme generates externalities for non-participants such an approach will capture only part of the programme's impact. Based on a unique large-scale quantitative survey

  20. Lupus vulgaris of external nose.

    Science.gov (United States)

    Bhandary, Satheesh Kumar; Ranganna, B Usha

    2008-12-01

    Lupus vulgaris is the commonest form of cutaneous tuberculosis which commonly involve trunk and buttocks. Lupus vulgaris affecting nose and face, are rarely reported in India. This study reports an unusual case of lupus vulgaris involving the external nose that showed dramatic outcome after six months of anti- tubercular treatment.

  1. [Treatment by external insulin pump].

    Science.gov (United States)

    Clavel, Sylvaine

    2010-12-01

    Since the recent recommendations by the French speaking association for research on diabetes and metabolic illnesses (Alfediam), treatment by insulin pump has found itself in competition with basal-bolus, a procedure using similar injections of insulin which has become a benchmark treatment. The latest Alfediam guidelines focus on defining ways of treating diabetics with an external insulin pump.

  2. Matchings with Externalities and Attitudes

    DEFF Research Database (Denmark)

    Branzei, Simina; Michalak, Tomasz; Rahwan, Talal;

    2013-01-01

    Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real-life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas ...

  3. Femoral Reconstruction Using External Fixation

    Directory of Open Access Journals (Sweden)

    Yevgeniy Palatnik

    2011-01-01

    Full Text Available Background. The use of an external fixator for the purpose of distraction osteogenesis has been applied to a wide range of orthopedic problems caused by such diverse etiologies as congenital disease, metabolic conditions, infections, traumatic injuries, and congenital short stature. The purpose of this study was to analyze our experience of utilizing this method in patients undergoing a variety of orthopedic procedures of the femur. Methods. We retrospectively reviewed our experience of using external fixation for femoral reconstruction. Three subgroups were defined based on the primary reconstruction goal lengthening, deformity correction, and repair of nonunion/bone defect. Factors such as leg length discrepancy (LLD, limb alignment, and external fixation time and complications were evaluated for the entire group and the 3 subgroups. Results. There was substantial improvement in the overall LLD, femoral length discrepancy, and limb alignment as measured by mechanical axis deviation (MAD and lateral distal femoral angle (LDFA for the entire group as well as the subgroups. Conclusions. The Ilizarov external fixator allows for decreased surgical exposure and preservation of blood supply to bone, avoidance of bone grafting and internal fixation, and simultaneous lengthening and deformity correction, making it a very useful technique for femoral reconstruction.

  4. Superconductor-ferromagnet bilayer under external drive: The role of vortex-antivortex matter

    Science.gov (United States)

    Frota, D. A.; Chaves, A.; Ferreira, W. P.; Farias, G. A.; Milošević, M. V.

    2016-03-01

    Using advanced Ginzburg-Landau simulations, we study the superconducting state of a thin superconducting film under a ferromagnetic layer, separated by an insulating oxide, in applied external magnetic field and electric current. The taken uniaxial ferromagnet is organized into a series of parallel domains with alternating polarization of out-of-plane magnetization, sufficiently strong to induce vortex-antivortex pairs in the underlying superconductor in absence of other magnetic field. We show the organization of such vortex-antivortex matter into rich configurations, some of which are not matching the periodicity of the ferromagnetic film. The variety of possible configurations is enhanced by applied homogeneous magnetic field, where additional vortices in the superconductor may lower the energy of the system by either annihilating the present antivortices under negative ferromagnetic domains or by lowering their own energy after positioning under positive ferromagnetic domains. As a consequence, both the vortex-antivortex reordering in increasing external field and the evolution of the energy of the system are highly nontrivial. Finally, we reveal the very interesting effects of applied dc electric current on the vortex-antivortex configurations, since resulting Lorentzian force has opposite direction for vortices and antivortices, while direction of the applied current with respect to ferromagnetic domains is of crucial importance for the interaction of the applied and the Meissner current, as well as the consequent vortex-antivortex dynamics—both of which are reflected in the anisotropic critical current of the system.

  5. Time-periodic and stationary solutions to the compressible Hall-magnetohydrodynamic system

    Science.gov (United States)

    Cheng, Ming

    2017-04-01

    We are concerned with the 3-D compressible Hall-magnetohydrodynamic system with a time-periodic external force in a periodic domain, and establish the existence of a strong time-periodic solution under some smallness and symmetry assumptions by adapting a new approach. The basic idea of the proof is the following. First, we prove the existence of a time-periodic solution to the linearized system by applying the Tychonoff fixed point theorem combined with the energy method and the decay estimates. From the details of the proof, we see that the initial data of the time-periodic solution to the linearized system lies in some convex hull. Then, we construct a set-value function, such that the fixed point of this function is a time-periodic solution of the compressible Hall-magnetohydrodynamic system. The existence of the fixed point is obtained by the Kakutani fixed point theorem. Moreover, we establish the uniqueness of the time-periodic solution and the existence of the stationary solution.

  6. Controlling chaos with localized heterogeneous forces in oscillator chains.

    Science.gov (United States)

    Chacón, Ricardo

    2006-10-01

    The effects of decreasing the impulse transmitted by localized periodic pulses on the chaotic behavior of homogeneous chains of coupled nonlinear oscillators are studied. It is assumed that when the oscillators are driven synchronously, i.e., all driving pulses transmit the same impulse, the chains display chaotic dynamics. It is shown that decreasing the impulse transmitted by the pulses of the two free end oscillators results in regularization with the whole array exhibiting frequency synchronization, irrespective of the chain size. A maximum level of amplitude desynchrony as the pulses of the two end oscillators narrow is typically found, which is explained as the result of two competing universal mechanisms: desynchronization induced by localized heterogeneous pulses and oscillation death of the complete chain induced by drastic decreasing of the impulse transmitted by such localized pulses. These findings demonstrate that decreasing the impulse transmitted by localized external forces can suppress chaos and lead to frequency-locked states in networks of dissipative systems.

  7. 过去2000年全球典型暖期的形成机制及其影响研究%Highlights of the Research Project on the Forcing and Impacts of the Warm Periods in the Past 2000 Years

    Institute of Scientific and Technical Information of China (English)

    葛全胜; 郑景云; 方修琦; 杨保; 刘健

    2015-01-01

    本文简要介绍了“过去2000年全球典型暖期的形成机制及其影响研究”项目取得的主要进展:(1)新建了40余条高分辨率气候序列,显著提高了过去2000年中国气候变化序列的覆盖度和时间分辨率;(2)揭示了暖期气候的空间协同特征及历史典型暖期与20世纪暖期气候格局的差异;(3)诊断了自然驱动的历史暖期与温室气体驱动的20世纪暖期形成机制的差异;(4)量化分析了过去2000年气候变化对中国社会经济的影响与响应过程,辨识了冷、暖期对中国社会经济影响的主要差异。上述研究成果增进了对年代至百年尺度气候变化特征与机制的认识,对我国适应未来气候变化具有参考价值。%Progresses in the research project of a study on the forcing and impacts of the warm periods in the past 2000 years, which funded from China Global Change Research Program, are summarized with highlights as fellows. (1) More than 40 new high-resolution climate series have been reconstructed, which improves the spa-tial coverage and the time resolution of the climate se-ries in the past 2000 years of China. (2) The spatial synergistic characteristics of warm periods and the differences between the spatial patterns of the Medieval Warm Period and the current warm period have been re-vealed. (3) The difference between the “ thermostat mechanism” for the Medieval Warming Period forced by increased solar radiation and the “stabilization mecha-nism” for the warming in the 20th century forced by in-creased greenhouse gases has been identified. (4) The climate change impact on social-economic system during Chinese history and the adaptation, particularly on the differences between the impacts of warm periods and the cold periods were identified quantitatively. These pro-gresses could not only improve the understanding on the characteristics and mechanisms of decadal to centennial climate change, but also provide

  8. Forced synchronization of quasiperiodic oscillations

    Science.gov (United States)

    Stankevich, N. V.; Kurths, J.; Kuznetsov, A. P.

    2015-01-01

    A model of a generator of quasiperiodic oscillations forced by a periodic pulse sequence is studied. We analyze synchronization when the autonomous generator demonstrates periodic, quasiperiodic, respective weakly chaotic oscillations. For the forced quasiperiodic oscillations a picture of synchronization, consisting of small-scale and large-scale structures was uncovered. It even includes the existence of stable the three-frequency tori. For the regime of weak chaos a partial destruction of this features and of the regime of three-frequency tori are found.

  9. Cluster forcing

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    .g. sustainability or quality of life. The purpose of this paper is to explore how and to what extent public sector interventions that aim at forcing cluster development in industries can support sustainable development as defined in the Brundtland tradition and more recently elaborated in such concepts as eco......, Portugal and New Zealand have adopted the concept. Public sector interventions that aim to support cluster development in industries most often focus upon economic policy goals such as enhanced employment and improved productivity, but rarely emphasise broader societal policy goals relating to e...... to the automotive sector in Wales. Specifically, the paper evaluates the "Accelerates" programme initiated by the Welsh Development Agency and elaborates on how and to what extent the Accelerate programme supports the development of a sustainable automotive industry cluster. The Accelerate programme was set up...

  10. Coriolis Force

    Science.gov (United States)

    Marciuc, Daly; Solschi, Viorel

    2017-04-01

    Understanding the Coriolis effect is essential for explaining the movement of air masses and ocean currents. The lesson we propose aims to familiarize students with the manifestation of the Coriolis effect. Students are guided to build, using the GeoGebra software, a simulation of the motion of a body, related to a rotating reference system. The mathematical expression of the Coriolis force is deduced, for particular cases, and the Foucault's pendulum is presented and explained. Students have the opportunity to deepen the subject, by developing materials related to topics such as: • Global Wind Pattern • Ocean Currents • Coriolis Effect in Long Range Shooting • Finding the latitude with a Foucault Pendulum

  11. Forced changes to twentieth century ENSO diversity in a last Millennium context

    Science.gov (United States)

    Stevenson, Samantha; Capotondi, Antonietta; Fasullo, John; Otto-Bliesner, Bette

    2017-03-01

    The El Niño/Southern Oscillation (ENSO) exhibits considerable differences between the evolution of individual El Niño and La Niña events (`ENSO diversity'), with significant implications for impacts studies. However, the degree to which external forcing may affect ENSO diversity is not well understood, due to both internal variability and potentially compensatory contributions from multiple forcings. The Community Earth System Model Last Millennium Ensemble (CESM LME) provides an ideal testbed for studying the sensitivity of twentieth century ENSO to forced climate changes, as it contains many realizations of the 850-2005 period with differing combinations of forcings. Metrics of ENSO amplitude and diversity are compared across LME simulations, and although forced changes to ENSO amplitude are generally small, forced changes to diversity are often detectable. Anthropogenic changes to greenhouse gas and ozone/aerosol emissions modify the persistence of Eastern and Central Pacific El Niño events, through shifts in the upwelling and zonal advective feedbacks; these influences generally cancel one another over the twentieth century. Other forcings can also be quite important: land use changes amplify Eastern Pacific El Niño events via modulating zonal advective heating, and orbital forcing tends to preferentially terminate twentieth century Central Pacific El Niño events due to enhanced eastern Pacific cooling during boreal winter and spring. Our results indicate that multiple anthropogenic and natural forcings can have substantial impacts on ENSO diversity, and suggest that correctly representing the net ENSO diversity response to climate change will depend on the precise balance between all these influences.

  12. Successful external fertilization in turbulent environments.

    Science.gov (United States)

    Serrao, E A; Pearson, G; Kautsky, L; Brawley, S H

    1996-05-28

    Mathematical and experimental simulations predict that external fertilization is unsuccessful in habitats characterized by high water motion. A key assumption of such predictions is that gametes are released in hydrodynamic regimes that quickly dilute gametes. We used fucoid seaweeds to examine whether marine organisms in intertidal and subtidal habitats might achieve high levels of fertilization by restricting their release of gametes to calm intervals. Fucus vesiculosus L. (Baltic Sea) released high numbers of gametes only when maximal water velocities were below ca. 0.2 m/s immediately prior to natural periods of release, which occur in early evening in association with lunar cues. Natural fertilization success measured at two sites was always close to 100%. Laboratory experiments confirmed that (i) high water motion inhibits gamete release by F. vesiculosus and by the intertidal fucoids Fucus distichus L. (Maine) and Pelvetia fastigiata (J. Ag.) DeToni (California), and (ii) showed that photosynthesis is required for high gamete release. These data suggest that chemical changes in the boundary layer surrounding adults during photosynthesis and/or mechanosensitive channels may modulate gamete release in response to changing hydrodynamic conditions. Therefore, sensitivity to environmental factors can lead to successful external fertilization, even for species living in turbulent habitats.

  13. [Frequency of external congenital abnormalities in abortions].

    Science.gov (United States)

    Arredondo de Arreola, G; López-Serna, N; Treviño-Alanís, M G; Russildi, J M; Arreola-Arredondo, B; Borrego, S A

    1992-01-01

    The purpose of this study was to calculate the incidence of external birth defects found in 1,650 aborted fetuses studied from September 1978 to February 1983 at the Department of Gynecology and Obstetrics of the University Hospital "Dr. José Eleuterio González" of the U.A.N.L. Medical School. Ninety five of fetuses had external birth defects and 85 had abnormalities in annexes. The Fisher exact test was applied to find the relationship between these abnormalities; no relationship was found. 67.4% had only one birth defect; 32.1% showed several defects. Those defects which were lethal constituted 67%, the majority being of the central nervous system. Defects found in the abdominal wall took second place in frequency followed by abnormalities in either extremity and ear defects. The birth defects seen in early gestational ages differ from those seen in live newborn babies. It is important to carry out morphological and teratological studies, not only in newborns but also during the embrion and fetal periods.

  14. Penetrating trauma to the external genitalia in Operation Iraqi Freedom.

    Science.gov (United States)

    Waxman, S; Beekley, A; Morey, A; Soderdahl, D

    2009-01-01

    This report details the incidence and description of trauma to the external genitalia experienced during Operation Iraqi Freedom at a United States Army Combat Support Hospital, and demonstrates that acceptable rates of testicular salvage are possible in the combat setting. The operating room logs and the Joint Theater Trauma Registry were used to conduct a retrospective review of the patients who sustained genitourinary (GU) injuries at an US Army Combat Support Hospital (CSH) in Iraq from 27 February 2007 to 14 August 2007. Of the 3595 battle trauma injuries seen at the CSH during the time period, 168 (4.7%) had one or more GU injuries for a total of 172 GU injuries. Of these patients, 115 (68%) with GU injuries had one or more injuries to the external genitalia for a total of 119 external GU injuries. Penetrating trauma to the penis and scrotum accounted for 59 of the injuries. In total, 43 testicles were injured in 34 patients (9 had bilateral injuries). In total, 32 testes were repaired primarily and 11 were removed. Injuries to the external genitalia continue to account for the vast majority of GU trauma in a combat setting. Of patients who presented with penetrating testicular trauma, there was a 74.4% salvage rate, which is higher than previous reports of combat external genitalia injuries. Treatment of penetrating trauma to the external genitalia in a combat setting requires attention to tissue preservation while coordinating associated surgical procedures.

  15. Intensity Tuning in Single Mode Microchip Nd:YAG Laser with External Cavity

    Institute of Scientific and Technical Information of China (English)

    TAN Yi-Dong; ZHANG Shu-Lian

    2006-01-01

    We investigate the characteristics of intensity tuning in a single mode microchip Nd:YAG laser with an external cavity. The undulation of laser intensity in a period of λ/2 change of the internal cavity length is observed.Two different optical feedback cases are performed. One is an external cavity reflector perfectly aligned and the other is an external cavity reflector tilted. However, the fluctuation frequency of laser intensity in a period of λ/2 change of the internal cavity length in these two cases is found to be determined by the ratio of external cavity length to internal cavity length. Meanwhile, for the tilted external cavity, the fluctuation frequency is also related to multiple feedbacks in the tilted external cavity.

  16. Externally Dispersed Interferometry for Precision Radial Velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D J; Muterspaugh, M W; Edelstein, J; Lloyd, J; Herter, T; Feuerstein, W M; Muirhead, P; Wishnow, E

    2007-03-27

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.

  17. Externally Dispersed Interferometry for Precision Radial Velocimetry

    CERN Document Server

    Erskine, D J; Edelstein, J; Lloyd, J; Herter, T; Feuerstein, W M; Muirhead, P; Wishnow, E

    2007-01-01

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.

  18. Dipolar fluids under external perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Klapp, Sabine H L [Stranski-Laboratorium fuer Physikalische und Theoretische Chemie Sekretariat TC7, Technische Universitaet Berlin, Strasse des 17. Juni 124, D-10623 Berlin (Germany)

    2005-04-20

    We discuss recent developments and present new findings on the structural and phase properties of dipolar model fluids influenced by various external perturbations. We concentrate on systems of spherical particles with permanent (point) dipole moments. Starting from what is known about the three-dimensional systems, particular emphasis is given to dipolar fluids in different confining situations involving both simple and complex (disordered) pore geometries. Further topics concern the effect of quenched positional disorder, the influence of external (electric or magnetic) fields, and the fluid-fluid phase behaviour of various dipolar mixtures. It is demonstrated that due to the translational-orientational coupling and due to the long range of dipolar interactions even simple perturbations such as hard walls can have a profound impact on the systems. (topical review)

  19. External observer reflections on QBism

    CERN Document Server

    Khrennikov, Andrei

    2015-01-01

    In this short review I present my personal reflections on QBism. I have no intrinsic sympathy neither to QBism nor to subjective interpretation of probability in general. However, I have been following development of QBism from its very beginning, observing its evolution and success, sometimes with big surprise. Therefore my reflections on QBism can be treated as "external observer" reflections. I hope that my representation of this interpretation of quantum mechanics (QM) has some degree of objectivity. It may be useful for researchers who are interested in quantum foundations, but do not belong to the QBism-community, because I tried to analyze essentials of QBism critically (i.e., not just emphasizing its advantages, as in a typical publication of QBists). QBists may be interested as well - in comments of an external observer who monitored development of this approach to QM during last 16 years. The second part of the paper is devoted to interpretations of probability, objective versus subjective, and view...

  20. Firm Search for External Knowledge

    DEFF Research Database (Denmark)

    Sofka, Wolfgang; Grimpe, Christoph

    2012-01-01

    The innovation performance of modern firms is increasingly determined by their ability to search and absorb external knowledge. However, after a certain threshold firms "oversearch" their environment and innovation performance declines. In this paper, we argue that prior literature has largely...... ignored the institutional context that provides or denies access to external knowledge at the country level. Combining institutional and knowledge search theory, we suggest that the market orientation of the institutional environment and the magnitude of institutional change influence when firms begin...... to experience the negative performance effects of oversearch. Based on a comprehensive sample of almost 8,000 firms from ten European countries, we find that institutions matter considerably for firms' search activity. Higher market orientation of institutions increases the effectiveness of firms' search...

  1. Wall force produced during disruptions

    Science.gov (United States)

    Strauss, H.; Paccagnella, R.; Breslau, J.

    2009-11-01

    The study of disruptions is of great importance for ITER. Previous work on disruptions [1] is extended to compute toroidally asymmetric wall force in ITER, using the M3D code. The disruptions are produced by n = 1 resistive wall modes or external kink modes. A thin wall resistive boundary model is used to calculate the wall forces. The symmetric wall force, produced by a VDE, and the asymmetric wall force, produced by n = 1 modes, are comparable in magnitude. It is found that the asymmetric and axisymmetric forces scale with the growth rate of the instability multiplied by the square of the current divided by magnetic field. A similar scaling was reported for VDEs in JET [2]. Numerically, the study of disruptions is very challenging. In the M3D extended MHD code, dealiasing was applied in the toroidal direction. Advection terms were treated with a numerical upwind method. These techniques provided sufficient numerical stability to simulate entire disruption events. [4pt] [1] R. Paccagnella, H. R. Strauss, and J. Breslau, Nucl. Fusion (2009) 49 035003. [2] V. Riccardo, T. C. Hender, P. J. Lomas, et al., Plasma Phys. Control. Fusion (2004)

  2. Network externalities across financial institutions

    OpenAIRE

    Castro Iragorri, Carlos Alberto; Preciado Pua, Sergio Andrés; Ordóñez Herrera, Juan Sebastián

    2016-01-01

    We propose and estimate a financial distress model that explicitly accounts for the interactions or spill-over effects between financial institutions, through the use of a spatial continuity matrix that is build from financial network data of inter bank transactions. Such setup of the financial distress model allows for the empirical validation of the importance of network externalities in determining financial distress, in addition to institution specific and macroeconomic covariates. The re...

  3. Externe Kosten in der Energiewirtschaft

    OpenAIRE

    Voß, Alfred; Friedrich, Rainer

    1994-01-01

    Als externe Effekte werden unbeteiligte Dritte betreffende Zusatzkosten oder Zusatznutzen verstanden, die sich in den jeweiligen Güterpreisen nicht wiederfinden und denen die Betroffenen nicht indifferent gegenüberstehen. Die gegenwärtige Energiebereitstellung und -nutzung ist in vielen Bereichen eine wesentliche Quelle der Belastung von Umwelt und Natur. Begriffe und Schlagworte wie Waldsterben, Tankerunglücke, Tschernobyl und Treibhauseffekt seien in diesem Zusammenhang erwähnt.

  4. Matching Games with Additive Externalities

    DEFF Research Database (Denmark)

    Branzei, Simina; Michalak, Tomasz; Rahwan, Talal

    2012-01-01

    Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas......, optimistic, and pessimistic behaviour, and provide both computational hardness results and polynomial-time algorithms for computing stable outcomes....

  5. ENDOSCOPIC DCR VERSUS EXTERNAL DCR

    Directory of Open Access Journals (Sweden)

    Rukma

    2015-04-01

    Full Text Available PURPOSE: To compare success rates of endoscopic dacryocystorhinostomy (DCR and external DCR for acquired nasolacrimal duct obstruction (NLDO. MATERIALS AND METHODS: A prospective comparative non randomized study of 64 patients who presented with acquired NLD obstruction to a tertiary hospital. They were fully evaluated to ascertain the site of obstruction and patients with distal obstruction were included in the study. 34 patients underwent endoscopic DCR and 30 patients underwent external DCR RESULTS: 64 patients were included in the study and 72 procedures carried out. Success was achieved in 65 cases and failure in 7. Of the 7 failed cases, anatomical obstruction at the fistula site was found in 3, whereas functional failure was found in 4. In our patients, endoscopic DCR had a significantly higher success rate than external DCR, 95.23% versus 83.33% (P = 0.03. CONCLUSIONS: The success rate of Endoscopic DCR for acquired NLDO in our group of patients was 95.23%, with endoscopic surgery showing better results.

  6. Conceptual challenges for internalising externalities

    DEFF Research Database (Denmark)

    Miguel, Brandão; Weidema, Bo Pedersen

    2013-01-01

    We analyse a number of different externalities to identify conceptual challenges for the practical implementation of their internalisation. Three issues were identified: i) The balance between compensation and technology change and the respective effects on the nominal and real GDP; ii) The relev......We analyse a number of different externalities to identify conceptual challenges for the practical implementation of their internalisation. Three issues were identified: i) The balance between compensation and technology change and the respective effects on the nominal and real GDP; ii......) The relevance and efficiency of different instruments for internalisation and compensation; and iii) Implementing internalisation over large geographical and temporal distances. We find taxation to be a more relevant and efficient tool for internalisation than insurance and litigation. With increasing...... geographical and especially temporal distance between the benefitting actor and the victim of the external cost, the involvement of a non-governmental intermediate actor becomes increasingly necessary to provide the short-term capital required to ensure a successful implementation....

  7. Individuals' insight into intrapersonal externalities

    Directory of Open Access Journals (Sweden)

    David J. Stillwell

    2012-07-01

    Full Text Available An intrapersonal externality exists when an individual's decisions affect the outcomes of her future decisions. It can result in decreasing or increasing average returns to the rate of consumption, as occurs in addiction or exercise. Experimentation using the Harvard Game, which models intrapersonal externalities, has found differences in decision making between drug users and control subjects, leading to the argument that these externalities influence the course of illicit drug use. Nevertheless, it is unclear how participants who behave optimally conceptualise the problem. We report two experiments using a simplified Harvard Game, which tested the differences in contingency knowledge between participants who chose optimally and participants who did not. Those who demonstrated optimal performance exhibited both a pattern of correct responses and systematic errors to questions about the payoff schedules. The pattern suggested that they learned explicit knowledge of the change in reinforcement on a trail-by-trial basis. They did not have, or need, a full knowledge of the historical interaction leading to each payoff. We also found no evidence of choice differences between participants who were given a guaranteed payment and participants who were paid contingent on their performance, but those given a guaranteed payment were able to report more contingency knowledge as the experiment progressed, suggesting that they explored more rather than settling into a routine. Experiment 2 showed that using a fixed inter-trial interval did not change the results.

  8. Internal and external influence in the US stock market

    Science.gov (United States)

    Borysov, Stanislav; Roudi, Yasser; Balatsky, Alexander

    2014-03-01

    We analyze the multivariate distribution of the US stock returns using pairwise interaction models, inspired by Ising models in glasses and neural networks. Using the inference methods from neural networks analysis we find unique descriptors of the dynamics of stock returns in periods of crisis. Our findings suggest that the near crash dynamics is primarily governed by external factors (external fields), while internal network structure (J couplings) are not significantly affected. This work is supported by Nordita and VR VCB 621-2012-2983.

  9. Frequency and force effects on psychophysical and myoelectric variables in low- intensity pinching tasks

    NARCIS (Netherlands)

    Visser, B.; Dieën, J.H. van; Veeger, D.; Looze, M.P. de; Douwes, M.

    2000-01-01

    Force and frequency in manual handling tasks are known risk factors for work related upper arm disorders. Three force levels and three frequencies are used to define the external load in a pinching task. The effects of these external loads on subjective and objective responses are studied. Subjectiv

  10. Hydrology of surface waters and thermohaline circulation during the last glacial period; Hydrologie des eaux de surface et circulation thermohaline au cours de la derniere periode glaciaire

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, L.

    1996-03-27

    Sedimentological studies on oceanic cores from the north Atlantic have revealed, over the last glacial period, abrupt climatic changes with a periodicity of several thousand years which contrasts strongly with the glacial-interglacial periodicity (several tens of thousand years). These periods of abrupt climate changes correspond to massive icebergs discharges into the north Atlantic. The aim of this work was to study the evolution of the thermohaline circulation in relation to these episodic iceberg discharges which punctuated the last 60 ka. To reconstruct the oceanic circulation in the past, we have analysed oxygen and carbon stable isotopes on benthic foraminifera from north Atlantic deep-sea cores. First of all, the higher temporal resolution of sedimentary records has enabled us to establish a precise chrono-stratigraphy for the different cores. Then, we have shown the close linkage between surface water hydrology and deep circulation, giving evidence of the sensibility of thermohaline circulation to melt water input in the north Atlantic ocean. Indeed, changes in deep circulation are synchronous from those identified in surface waters and are recorded on a period which lasted {approx} 1500 years. Deep circulation reconstructions, before and during a typical iceberg discharge reveal several modes of circulation linked to different convection sites at the high latitudes of the Atlantic basin. Moreover, the study of the last glacial period gives the opportunity to differentiate circulation changes due to the external forcing (variations of the orbital parameters) and those linked to a more local forcing (icebergs discharges). 105 refs., 50 figs., 14 tabs., 4 appends.

  11. Axial force measurement for esophageal function testing

    Institute of Scientific and Technical Information of China (English)

    Flemming H Gravesen; Peter Funch-Jensen; Hans Gregersen; Asbjφrn Mohr Drewes

    2009-01-01

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

  12. Axial force measurement for esophageal function testing.

    Science.gov (United States)

    Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr

    2009-01-14

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

  13. Externalizing Problems through Art and Writing: Experience of Process and Helpfulness

    Science.gov (United States)

    Keeling, Margaret L.; Bermudez, Maria

    2006-01-01

    Externalization of problems as a component of narrative therapy has been well defined by such authors as Epston and White, and Freedman and Combs. This study reflects the voices and experiences of 17 participants who engaged in an innovative externalization exercise combining sculpture and journaling over a period of 4 weeks. In an attempt to…

  14. Brittle fracture in a periodic structure with internal potential energy. Quasi-static analysis

    CERN Document Server

    Mishuris, Gennady S

    2013-01-01

    We consider a linearly elastic body consisting of two equal symmetrically arranged layers (or half-planes) connected by a structured interface as a prospective crack path. The interface is comprised by periodic discrete system of bonds. In the initial state with no external forces, the bonds are assumed to be stressed in such a way that tensile and compressive forces of the same value alternate. In the general considerations, the layers are assumed to be of a general, unspecified {\\em periodic} structure, where such self-equilibrated residual stresses can also exist. A two-line chain and an anisotropic lattice are examined as illustrative examples. We consider the states of the body-with-a-crack under the residual stresses and under a combined action of the remote forces and residual stresses. Analytical solutions to the considered problems are presented. The solutions are based on a selective discrete transform introduced. In particular, it is found that a formula for local-to-global energy release ratio, wr...

  15. 上海浦东南汇地区流动人口“三病”检疫10年监测分析%Analysis of monitoring of “quarantine of three diseases” among external floating population for a period of 10 years in Nanhui District, Shanghai

    Institute of Scientific and Technical Information of China (English)

    宋海红

    2011-01-01

    目的 了解和分析上海南汇地区外来流动人员血吸虫病、疟疾、丝虫病检疫的现况,为今后的外来人员管理和监测工作提供对策.方法 采用免疫酶染技术及三联抗原片,对外来流动人员进行血吸虫免疫测定、疟疾血片免疫测定及疟原虫血检和丝虫免疫测定.结果 接受检疫的54 386名外来流动人员中,抗体总阳性率为0.69%,其中,血吸虫抗体阳性率为0.24%,疟疾阳性率为0.36%,丝虫阳性率为0.09%.结论 由于大量外来流动人员的涌入,导致血吸虫病、疟疾、丝虫病流行的危险因素依然存在,因而要加强对外来人员的监测,规范流动人口管理的条例和管理方法,以控制传染源.%Objectives To understand infectious status of schistosomiasis,malaria and filariasis in external floating population in Nanhui District of Shanghai. Methods The infectious status of schistosomiasis,malaria and fialrasis in external floating population was detected with immune enzyme staining,and immunoassay. Results Totally 54 386 people moved in from outside of Nanhui District were detected and the antibody positive rate was 0.69% ,being 0.24% for schistosoma,0.36% for plasmodium and 0.09% for filaria. Conclusion Due to influx of foreign travelers,there is the risk of prevalence of schistosomiasis,filariasis and malaria,thus the quarantine and monitoring of the three infective diseases should be strengthened.

  16. Unstable and stable periodicities in thermally sensitive electroreceptors of catfish

    Science.gov (United States)

    Moss, Frank; Pei, Xing; Braun, Hans; Schafer, Klaus; Peters, Rob

    1997-03-01

    A statistical technique for distinguishing and counting unstable periodic orbits (UPOs) and stable limit cycles (LCs), based on their differing phase space topologies, has recently been developed(D. Pierson and F. Moss, Phys. Rev. Lett. 75, 2124 (1995)). Because the method is able to operate effectively on data files from noisy dynamical sources, it is uniquely effective when operating on data from biological sources, for example, weakly stimulated sensory neurons(X. Pei and F. Moss, Nature 379, 618 (1996)). Here we report the results of a study of bifurcations between UPOs and LCs in the electroreceptor organs of the catfish with the surface temperature of the receptors used as the bifurcation parameter. These organs have previously been shown to exhibit an internal near sub threshold oscillator which may account for the spontaneous appearance of the UPOs for certain values of the temperature. In previous experiments on different sensory systems (possibly of lower dimension) external periodic forcing was necessary for the appearance of UPOs.

  17. Multiresonance of energy transport and absence of heat pump in a force-driven lattice.

    Science.gov (United States)

    Zhang, Song; Ren, Jie; Li, Baowen

    2011-09-01

    Energy transport control in low dimensional nanoscale systems has attracted much attention in recent years. In this paper, we investigate the energy transport properties of the Frenkel-Kontorova lattice subject to a periodic driving force, in particular, the resonance behavior of the energy current by varying the external driving frequency. It is discovered that, in certain parameter ranges, multiple resonance peaks, instead of a single resonance, emerge. By comparing the nonlinear lattice model with a harmonic chain, we unravel the underlying physical mechanism for such a resonance phenomenon. Other parameter dependencies of the resonance behavior are examined as well. Finally, we demonstrate that heat pumping is actually absent in this force-driven model.

  18. Hysteresis-induced bifurcation and chaos in a magneto-rheological suspension system under external excitation

    Science.gov (United States)

    Hailong, Zhang; Enrong, Wang; Fuhong, Min; Ning, Zhang

    2016-03-01

    The magneto-rheological damper (MRD) is a promising device used in vehicle semi-active suspension systems, for its continuous adjustable damping output. However, the innate nonlinear hysteresis characteristic of MRD may cause the nonlinear behaviors. In this work, a two-degree-of-freedom (2-DOF) MR suspension system was established first, by employing the modified Bouc-Wen force-velocity (F-v) hysteretic model. The nonlinear dynamic response of the system was investigated under the external excitation of single-frequency harmonic and bandwidth-limited stochastic road surface. The largest Lyapunov exponent (LLE) was used to detect the chaotic area of the frequency and amplitude of harmonic excitation, and the bifurcation diagrams, time histories, phase portraits, and power spectrum density (PSD) diagrams were used to reveal the dynamic evolution process in detail. Moreover, the LLE and Kolmogorov entropy (K entropy) were used to identify whether the system response was random or chaotic under stochastic road surface. The results demonstrated that the complex dynamical behaviors occur under different external excitation conditions. The oscillating mechanism of alternating periodic oscillations, quasi-periodic oscillations, and chaotic oscillations was observed in detail. The chaotic regions revealed that chaotic motions may appear in conditions of mid-low frequency and large amplitude, as well as small amplitude and all frequency. The obtained parameter regions where the chaotic motions may appear are useful for design of structural parameters of the vibration isolation, and the optimization of control strategy for MR suspension system. Projects supported by the National Natural Science Foundation of China (Grant Nos. 51475246, 51277098, and 51075215), the Research Innovation Program for College Graduates of Jiangsu Province China (Grant No. KYLX15 0725), and the Natural Science Foundation of Jiangsu Province of China (Grant No. BK20131402).

  19. Analysis of Periodically Varying Gear Mesh Systems with Coulomb Friction Using Floquet Theory

    Science.gov (United States)

    VAISHYA, M.; SINGH, R.

    2001-06-01

    This article presents a new analytical model of a gear pair with time varying mesh stiffness, viscous damping and sliding friction parameters. Unlike previous models, the excitation consists of three separate terms, namely the unloaded transmission error, time-invariant external torque and the periodically varying sliding friction force. A Coulomb friction model is considered using first a quasi-static mean transmitted load that is represented by the Meissner equation. Then, a truly dynamic force between gear teeth is described that leads to a triangular function, and after appropriate substitutions, this assumes the form of the Bessel equation of the one-third order. For the damped Meissner equation, the forced vibration response is found with the application of Floquet theory. Exact integrals are calculated for the state transition matrix in a piecewise manner, instead of using the Fourier series expansion, thus eliminating the mode truncation errors. From the state transition matrix, unstable zones are identified and the actual forced response of the system is found in terms of dynamic transmission error for these zones. With the aid of an example, the significance of sliding friction on system response and stability is examined. Finally, key advantages and the need for analytical methods are demonstrated for such systems.

  20. Quantifying Interparticle Forces and Heterogeneity in 3D Granular Materials.

    Science.gov (United States)

    Hurley, R C; Hall, S A; Andrade, J E; Wright, J

    2016-08-26

    Interparticle forces in granular materials are intimately linked to mechanical properties and are known to self-organize into heterogeneous structures, or force chains, under external load. Despite progress in understanding the statistics and spatial distribution of interparticle forces in recent decades, a systematic method for measuring forces in opaque, three-dimensional (3D), frictional, stiff granular media has yet to emerge. In this Letter, we present results from an experiment that combines 3D x-ray diffraction, x-ray tomography, and a numerical force inference technique to quantify interparticle forces and their heterogeneity in an assembly of quartz grains undergoing a one-dimensional compression cycle. Forces exhibit an exponential decay above the mean and partition into strong and weak networks. We find a surprising inverse relationship between macroscopic load and the heterogeneity of interparticle forces, despite the clear emergence of two force chains that span the system.

  1. Thought Experiments on Gravitational Forces

    CERN Document Server

    Lynden-Bell, Donald

    2013-01-01

    Large contributions to the near closure of the Universe and to the acceleration of its expansion are due to the gravitation of components of the stress-energy tensor other than its mass density. To familiarise astronomers with the gravitation of these components we conduct thought experiments on gravity, analogous to the real experiments that our forebears conducted on electricity. By analogy to the forces due to electric currents we investigate the gravitational forces due to the flows of momentum, angular momentum, and energy along a cylinder. Under tension the gravity of the cylinder decreases but the 'closure' of the 3-space around it increases. When the cylinder carries a torque the flow of angular momentum along it leads to a novel helical interpretation of Levi-Civita's external metric and a novel relativistic effect. Energy currents give gravomagnetic effects in which parallel currents repel and antiparallel currents attract, though such effects must be added to those of static gravity. The gravity of...

  2. Characterization of Akiyama probe applied to dual-probes atomic force microscope

    Science.gov (United States)

    Wang, Hequn; Gao, Sitian; Li, Wei; Shi, Yushu; Li, Qi; Li, Shi; Zhu, Zhendong

    2016-10-01

    The measurement of nano-scale line-width has always been important and difficult in the field of nanometer measurements, while the rapid development of integrated circuit greatly raises the demand again. As one kind of scanning probe microscope (SPM), atomic force microscope (AFM) can realize quasi three-dimensional measurement, which is widely used in nanometer scale line-width measurement. Our team researched a dual-probes atomic force microscope, which can eliminate the prevalent effect of probe width on measurement results. In dual-probes AFM system, a novel head are newly designed. A kind of self-sensing and self-exciting probes which is Nanosensors cooperation's patented probe—Akiyama probe, is used in this novel head. The Akiyama probe applied to dual-probe atomic force microscope is one of the most important issues. The characterization of Akiyama probe would affect performance and accuracy of the whole system. The fundamental features of the Akiyama probe are electrically and optically characterized in "approach-withdraw" experiments. Further investigations include the frequency response of an Akiyama probe to small mechanical vibrations externally applied to the tip and the effective loading force yielding between the tip and the sample during the periodic contact. We hope that the characterization of the Akiyama probe described in this paper will guide application for dual-probe atomic force microscope.

  3. External foam layers to football helmets reduce head impact severity.

    Science.gov (United States)

    Nakatsuka, Austin S; Yamamoto, Loren G

    2014-08-01

    Current American football helmet design has a rigid exterior with a padded interior. Softening the hard external layer of the helmet may reduce the impact potential of the helmet, providing extra head protection and reducing its use as an offensive device. The objective of this study is to measure the impact reduction potential provided by external foam. We obtained a football helmet with built-in accelerometer-based sensors, placed it on a boxing mannequin and struck it with a weighted swinging pendulum helmet to mimic the forces sustained during a helmet-to-helmet strike. We then applied layers of 1.3 cm thick polyolefin foam to the exterior surface of the helmets and repeated the process. All impact severity measures were significantly reduced with the application of the external foam. These results support the hypothesis that adding a soft exterior layer reduces the force of impact which may be applicable to the football field. Redesigning football helmets could reduce the injury potential of the sport.

  4. 赴利比里亚维和部队轮换期间埃博拉防控的实践与思考%Practice and Reflection on Preventing and Controlling the Ebolavirus for Chinese Peacekeeping Forces to Liberia during Cyclic Permutation Period

    Institute of Scientific and Technical Information of China (English)

    朱焱华; 邴峰; 琴明贤; 鄢雷

    2015-01-01

    本文介绍了利比里亚地区埃博拉疫情和第16和第17批赴利比里亚维和部队轮换期间埃博拉疫情防控的主要措施,提出了坚持联动及时的疫情应对、明确层次分明的防控责任、理顺军地协同的工作关系、严格轮换期间的生活管理、加强全程伴随的心理保障等方面的体会思考.%Ebola epidemic situation in Liberia region and main prevention and control measures for the ebolavirus in the 16 th and 17 th detachments of Chinese peacekeeping forces to Liberia during cyclic permutation period were intro-duced in this paper. Experiences have been summarized in this study, such as keeping combined action timely for epi-demic outbreak, clarifying the responsibilities of prevention and control, coordinating the working relationship between the military and the local government, strictly managing the life regulation during cyclic permutation period and enhancing the psychological security during the whole mission.

  5. Exportação de democracia na política externa norte-americana no pós-Guerra-Fria: doutrinas e o uso da força Exporting of democracy in American foreign policy in the post-Cold War period: the doctrine and the use of force

    Directory of Open Access Journals (Sweden)

    Maria Helena de Castro Santos

    2010-07-01

    Full Text Available O artigo analisa os pilares da política externa americana no pós-guerra fria, mirando o lugar que ai ocupa democracia e sua relação com segurança. Busca-se mais especificamente as bases da doutrina da política externa que justificam a exportação de democracia pelo uso da força. Utilizou-se a análise de conteúdo quantitativa e qualitativa de 415 discursos dos Presidentes e Secretários de Estado entre 1989 e 2008.The article analyses the pillars of the American foreign policy in the post-cold war period, focusing on the importance democracy vis-à-vis security plays in it as well as their relationship. More specifically the work aims to define the bases of the doctrine of the foreign policy that justify exporting democracy by the use of force. It was used quantitative and qualitative content analysis of 414 speeches of the Presidents and Secretaries of States in the period 1989-2008.

  6. Ultrasonic Force Microscopies

    Science.gov (United States)

    Kolosov, Oleg; Briggs, Andrew

    Ultrasonic Force Microscopy, or UFM, allows combination of two apparently mutually exclusive requirements for the nanomechanical probe—high stiffness for the efficient indentation and high mechanical compliance that brings force sensitivity. Somewhat inventively, UFM allows to combine these two virtues in the same cantilever by using indention of the sample at high frequency, when cantilever is very rigid, but detecting the result of this indention at much lower frequency. That is made possible due to the extreme nonlinearity of the nanoscale tip-surface junction force-distance dependence, that acts as "mechanical diode" detecting ultrasound in AFM. After introducing UFM principles, we discuss features of experimental UFM implementation, and the theory of contrast in this mode, progressing to quantitative measurements of contact stiffness. A variety of UFM applications ranging from semiconductor quantum nanostructures, graphene, very large scale integrated circuits, and reinforced ceramics to polymer composites and biological materials is presented via comprehensive imaging gallery accompanied by the guidance for the optimal UFM measurements of these materials. We also address effects of adhesion and topography on the elasticity imaging and the approaches for reducing artifacts connected with these effects. This is complemented by another extremely useful feature of UFM—ultrasound induced superlubricity that allows damage free imaging of materials ranging from stiff solid state devices and graphene to biological materials. Finally, we proceed to the exploration of time-resolved nanoscale phenomena using nonlinear mixing of multiple vibration frequencies in ultrasonic AFM—Heterodyne Force Microscopy, or HFM, that also include mixing of ultrasonic vibration with other periodic physical excitations, eg. electrical, photothermal, etc. Significant section of the chapter analyzes the ability of UFM and HFM to detect subsurface mechanical inhomogeneities, as well as

  7. External debt and capital flight in Nigeria: Is there a revolving door?

    National Research Council Canada - National Science Library

    OT Ajilore

    2014-01-01

    Using the residual method of capital flight estimation, this paper estimates Nigerian capital flight over the period 1970 - 2001 and finds a close correlation between external debt and capital flight flows...

  8. Skepticism, Contextualism, Externalism and Modality

    Directory of Open Access Journals (Sweden)

    Ron Wilburn

    2006-12-01

    Full Text Available In this paper, I argue for the following claims. Contextualist strategies to tame or localize epistemic skepticism are hopeless if contextualist factors are construed internalistically. However, because efforts to contextualize externalism via subjunctive conditional analysis court circularity, it is only on an internalistic interpretation that contextualist strategies can even be motivated. While these claims do not give us an argument for skepticism, they do give us an argument that contextualism, as such, is not likely to provide us with an argument against skepticism.

  9. Leveraging External Sources of Innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2014-01-01

    own specific set of mechanisms and conditions. Integrating innovations has been mostly studied from an absorptive capacity perspective, with less attention given to the impact of competencies and culture (including “not invented here”). Commercializing innovations puts the most emphasis on how......” in a way inconsistent with earlier definitions in innovation management. The paper concludes with recommendations for future research that include examining the end-to-end innovation commercialization process, and studying the moderators and limits of leveraging external sources of innovation....

  10. Theoretical analysis of natural frequency of externally prestressed concrete beam based on rigidity correction

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A dynamic test on externally prestressed simply supported concrete beams separately with three typical types of tendon distributions was conducted. The results show that the natural frequencies of the beams increase with the increase in the prestressing force at the tensioning stage, and the natural frequencies decrease after the cracks occur in the beams. Following the calculation formula of natural frequency of externally prestressed beam, which was reported in a literature, the natural frequencies of the...

  11. Novel Rigid External Distraction Device Improves Stability and Controls the Vector During Midfacial Advancement.

    Science.gov (United States)

    Resnick, Cory M; Rottgers, Stephen Alex; Langenfeld, Christopher C; Mulliken, John B; Padwa, Bonnie L

    2016-06-01

    The major limitation of the rigid external devices currently used for midfacial distraction after subcranial Le Fort III osteotomies is the ductile wire that connects the midface to the device, which makes it difficult to control the vector and force during distraction. The authors describe a novel external appliance that addresses this and other problems of contemporary devices, and application of a custom cranial template that facilitates precise placement of the device to achieve the planned vector of distraction.

  12. Forced response of the East Asian summer rainfall over the past millennium: results from a coupled model simulation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jian; Wang, Hongli; Ti, Ruyuan [Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, State Key Laboratory of Lake Science and Environment, Nanjing (China); Wang, Bin [University of Hawaii at Manoa, Department of Meteorology and IPRC, Honolulu, HI (United States); Kuang, Xueyuan [Nanjing University, School of Atmospheric Sciences, Nanjing (China)

    2011-01-15

    The centennial-millennial variation of the East Asian summer monsoon (EASM) precipitation over the past 1000 years was investigated through the analysis of a millennium simulation of the coupled ECHO-G model. The model results indicate that the centennial-millennial variation of the EASM is essentially a forced response to the external radiative forcing (insolation, volcanic aerosol, and green house gases). The strength of the response depends on latitude; and the spatial structure of the centennial-millennial variation differs from the interannual variability that arises primarily from the internal feedback processes within the climate system. On millennial time scale, the extratropical and subtropical precipitation was generally strong during Medieval Warm Period (MWP) and weak during Little Ice Age (LIA). The tropical rainfall is insensitive to the effective solar radiation forcing (insolation plus radiative effect of volcanic aerosols) but significantly responds to the modern anthropogenic radiative forcing. On centennial time scale, the variation of the extratropical and subtropical rainfall also tends to follow the effective solar radiation forcing closely. The forced response features in-phase rainfall variability between the extratropics and subtropics, which is in contrast to the anti-correlation on the interannual time scale. Further, the behavior of the interannual-decadal variation in the extratropics is effectively modulated by change of the mean states on the millennial time scale, suggesting that the structure of the internal mode may vary with significant changes in the external forcing. These findings imply that on the millennial time scale, (a) the proxy data in the extratropical EA may more sensitively reflect the EASM rainfall variations, and (b) the Meiyu and the northern China rainfall provide a consistent measure for the EASM strength. (orig.)

  13. The structure of MHD turbulence under an external magnetic field: results from simulations on elongated domains

    Science.gov (United States)

    Zhai, X. M.; Yeung, P. K.

    2016-11-01

    Turbulence in an electrically conducting fluid in the limit of low magnetic Reynolds number is, because of the Lorentz force due to an external magnetic field, very different from classical turbulence at both the large scales and the small scales. The importance of minimizing finite domain-size effects on the large scale development has often tended to limit the Reynolds number reached in the past. In this work we use periodic domains stretched along the magnetic field with aspect ratio up to 8 and beyond. The initial state is obtained from decaying isotropic turbulence with large-eddy length scales of order 1% of the length of the domain. After a transient period the kinetic energy returns to a power law decay while the integral length scales in the direction parallel to the magnetic field show preferential growth. At early times the parallel velocity component becomes stronger than the other two but this anisotropy is subsequently reversed under the combined effects of anisotropic Joule dissipation and viscous dissipation. The small scales show characteristics of quasi two-dimensional behavior in the transverse plane. Results over a range of magnetic interaction parameters and Reynolds numbers are compared with known theoretical predictions. Supported by NSF Grant CBET-1510749 and supercomputer resources at TACC/XSEDE and ALCF.

  14. Glenohumeral contact forces and muscle forces evaluated in wheelchair-related activities of daily living in able-bodied subjects versus subjects with paraplegia and tetraplegia

    NARCIS (Netherlands)

    van Drongelen, S; van der Woude, LH; Janssen, Thomas W. J.; Angenot, EL; Chadwick, EK; Veeger, DirkJan (H. E. J.)

    Objective: To estimate the differences in glenohumeral contact forces and shoulder muscle forces between able-bodied subjects and subjects with paraplegia and tetraplegia during wheelchair-related activities of daily living (ADLs). Design: Kinematics and external forces were measured during

  15. Glenohumeral contact forces and muscle forces evaluated in wheelchair-related activities of daily living in able-bodied subjects versus subjects with paraplegia and tetraplegia

    NARCIS (Netherlands)

    van Drongelen, S; van der Woude, LH; Janssen, Thomas W. J.; Angenot, EL; Chadwick, EK; Veeger, DirkJan (H. E. J.)

    2005-01-01

    Objective: To estimate the differences in glenohumeral contact forces and shoulder muscle forces between able-bodied subjects and subjects with paraplegia and tetraplegia during wheelchair-related activities of daily living (ADLs). Design: Kinematics and external forces were measured during wheelcha

  16. Steady State Convergence Acceleration of the Generalized Lattice Boltzmann Equation with Forcing Term through Preconditioning

    CERN Document Server

    Premnath, Kannan N; Banerjee, Sanjoy

    2008-01-01

    Several applications exist in which lattice Boltzmann methods (LBM) are used to compute stationary states of fluid motions, particularly those driven or modulated by external forces. Standard LBM, being explicit time-marching in nature, requires a long time to attain steady state convergence, particularly at low Mach numbers due to the disparity in characteristic speeds of propagation of different quantities. In this paper, we present a preconditioned generalized lattice Boltzmann equation (GLBE) with forcing term to accelerate steady state convergence to flows driven by external forces. The use of multiple relaxation times in the GLBE allows enhancement of the numerical stability. Particular focus is given in preconditioning external forces, which can be spatially and temporally dependent. In particular, correct forms of moment-projections of source/forcing terms are derived such that they recover preconditioned Navier-Stokes equations with non-uniform external forces. As an illustration, we solve an extende...

  17. Forces predicted at the ankle during running.

    Science.gov (United States)

    Burdett, R G

    1982-01-01

    A biomechanical model of the ankle joint was developed and was used to predict the forces at the ankle during the stance phase of running. Measurements from five cadavers were averaged to obtain insertion points and directions of pull of equivalent tendons with respect to the assumed center of the ankle joint. A minimum joint force solution was obtained by assuming that only two equivalent muscle groups could exert force at one time. Three subjects ran at 4.47 m/s across a force platform that recorded the external forces and moments acting on the foot. Cinematography was used to measure the foot and leg positions during stance. Peak resultant joint forces ranging from 9.0 to 13.3 times body weight and peak Achilles tendon forces ranging from 5.3 to 10.0 times body weight were predicted. Small variations in some cases resulted in large differences in predicted forces. The highest tendon forces predicted exceeded those reported to cause damage to cadaver tendons in other studies.

  18. Outcomes after External Iliac and Femoral Vascular Injuries.

    Science.gov (United States)

    Kim, Jerry J; Alipour, Hamid; Yule, Arthur; Plurad, David S; Koopmann, Matthew; Putnam, Brant; de Virgilio, Christian; Kim, Dennis Y

    2016-05-01

    Vascular injuries occurring at the junction of the trunk and lower extremity are uncommon yet challenging because of their location and potential for associated truncal injuries. The purpose of this study was to examine and compare outcomes among patients sustaining external iliac and femoral vascular injuries. We performed a 13-year retrospective analysis of our level 1 trauma center database to identify and compare patients with external iliac and femoral vessel injuries. Multiple logistic regression analysis was performed to identify independent predictors for mortality. During the study period, 135 patients with a median (interquartile range [IQR]) age of 25 (20-35) years were identified with external iliac (n = 29) and femoral vascular injuries (n = 106). The majority were male (85.9%) with a penetrating mechanism (84.5%), and the median (IQR) Injury Severity Score (ISS) was 16 (11-26). The overall mortality rate was 14.1%. In comparison with patients with femoral vascular injuries, patients with external iliac injuries presented with higher ISS (25 vs. 16, P vascular injuries, external iliac vascular injuries are associated with higher blood loss, more intense resuscitation, higher disability and mortality in patients sustaining junctional groin injuries. Early recognition and application of damage control techniques and resuscitative practices may result in improved outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Quantum Electrodynamics on background external fields

    CERN Document Server

    Marecki, P

    2003-01-01

    The quantum electrodynamics in presence of background external fields is developed. Modern methods of local quantum physics allow to formulate the theory on arbitrarily strong possibly time-dependent external fields. Non-linear observables which depend only locally on the external field are constructed. The tools necessary for this formulation, the parametrices of the Dirac operator, are investigated.

  20. 46 CFR 154.452 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false External pressure. 154.452 Section 154.452 Shipping... Independent Tank Type C and Process Pressure Vessels § 154.452 External pressure. The design external pressure...) for tanks without a vacuum relief valve. P2=0, or the pressure relief valve setting for an enclosed...