Some heuristic procedures for analyzing random vibration of nonlinear oscillators.
Crandall, S. H.
1971-01-01
The stationary response of a lightly damped nonlinear oscillator subjected to wideband random excitation can be examined as an example of thermal equilibrium. It may be assumed that the response consists of a series of free-vibration cycles with small random fluctuations in phase and amplitude. Certain statistical properties of the response can be estimated by averaging corresponding properties of the free vibration with respect to cycle amplitude distributions. Such heuristic procedures for determining the expected frequency and the autocorrelation function of the stationary response are outlined. Some additional results concerning first-passage problems for nonlinear oscillators are included.
Fully Digital Chaotic Oscillators Applied to Pseudo Random Number Generation
Mansingka, Abhinav S.
2012-05-01
adapted for pseudo random number generation by truncating statistically defective bits. Finally, a novel post-processing technique using the Fibonacci series is proposed and implemented with a non-autonomous driven hyperchaotic system to provide pseudo random number generators with high nonlinear complexity and controllable period length that enables full utilization of all branches of the chaotic output as statistically secure pseudo random output.
Random graph theory and neuropercolation for modeling brain oscillations at criticality.
Kozma, Robert; Puljic, Marko
2015-04-01
Mathematical approaches are reviewed to interpret intermittent singular space-time dynamics observed in brain imaging experiments. The following aspects of brain dynamics are considered: nonlinear dynamics (chaos), phase transitions, and criticality. Probabilistic cellular automata and random graph models are described, which develop equations for the probability distributions of macroscopic state variables as an alternative to differential equations. The introduced modular neuropercolation model is motivated by the multilayer structure and dynamical properties of the cortex, and it describes critical brain oscillations, including background activity, narrow-band oscillations in excitatory-inhibitory populations, and broadband oscillations in the cortex. Input-induced and spontaneous transitions between states with large-scale synchrony and without synchrony exhibit brief episodes with long-range spatial correlations as observed in experiments. Copyright © 2014 Elsevier Ltd. All rights reserved.
A coupled well-balanced and random sampling scheme for computing bubble oscillations*
Directory of Open Access Journals (Sweden)
Jung Jonathan
2012-04-01
Full Text Available We propose a finite volume scheme to study the oscillations of a spherical bubble of gas in a liquid phase. Spherical symmetry implies a geometric source term in the Euler equations. Our scheme satisfies the well-balanced property. It is based on the VFRoe approach. In order to avoid spurious pressure oscillations, the well-balanced approach is coupled with an ALE (Arbitrary Lagrangian Eulerian technique at the interface and a random sampling remap. Nous proposons un schéma de volumes finis pour étudier les oscillations d’une bulle sphérique de gaz dans l’eau. La symétrie sphérique fait apparaitre un terme source géométrique dans les équations d’Euler. Notre schéma est basé sur une approche VFRoe et préserve les états stationnaires. Pour éviter les oscillations de pression, l’approche well-balanced est couplée avec une approche ALE (Arbitrary Lagrangian Eulerian, et une étape de projection basée sur un échantillonage aléatoire.
Huang, Liang; Yang, Rui; Lai, Ying-Cheng; Ferry, David K
2013-02-27
Quantum interference causes a wavefunction to have sensitive spatial dependence, and this has a significant effect on quantum transport. For example, in a quantum-dot system, the conductance can depend on the lead positions. We investigate, for graphene quantum dots, the conductance variations with the lead positions. Since for graphene the types of boundaries, e.g., zigzag and armchair, can fundamentally affect the quantum transport characteristics, we focus on rectangular graphene quantum dots, for which the effects of boundaries can be systematically studied. For both zigzag and armchair horizontal boundaries, we find that changing the positions of the leads can induce significant conductance variations. Depending on the Fermi energy, the variations can be either regular oscillations or random conductance fluctuations. We develop a physical theory to elucidate the origin of the conductance oscillation/fluctuation patterns. In particular, quantum interference leads to standing-wave-like-patterns in the quantum dot which, in the absence of leads, are regulated by the energy-band structure of the corresponding vertical graphene ribbon. The observed 'coexistence' of regular oscillations and random fluctuations in the conductance can be exploited for the development of graphene-based nanodevices.
Mid-infrared optical parametric oscillator pumped by an amplified random fiber laser
Shang, Yaping; Shen, Meili; Wang, Peng; Li, Xiao; Xu, Xiaojun
2017-01-01
Recently, the concept of random fiber lasers has attracted a great deal of attention for its feature to generate incoherent light without a traditional laser resonator, which is free of mode competition and insure the stationary narrow-band continuous modeless spectrum. In this Letter, we reported the first, to the best of our knowledge, optical parametric oscillator (OPO) pumped by an amplified 1070 nm random fiber laser (RFL), in order to generate stationary mid-infrared (mid-IR) laser. The experiment realized a watt-level laser output in the mid-IR range and operated relatively stable. The use of the RFL seed source allowed us to take advantage of its respective stable time-domain characteristics. The beam profile, spectrum and time-domain properties of the signal light were measured to analyze the process of frequency down-conversion process under this new pumping condition. The results suggested that the near-infrared (near-IR) signal light `inherited' good beam performances from the pump light. Those would be benefit for further develop about optical parametric process based on different pumping circumstances.
A shift to randomness of brain oscillations in people with autism.
Lai, Meng-Chuan; Lombardo, Michael V; Chakrabarti, Bhismadev; Sadek, Susan A; Pasco, Greg; Wheelwright, Sally J; Bullmore, Edward T; Baron-Cohen, Simon; Suckling, John
2010-12-15
Resting-state functional magnetic resonance imaging (fMRI) enables investigation of the intrinsic functional organization of the brain. Fractal parameters such as the Hurst exponent, H, describe the complexity of endogenous low-frequency fMRI time series on a continuum from random (H = .5) to ordered (H = 1). Shifts in fractal scaling of physiological time series have been associated with neurological and cardiac conditions. Resting-state fMRI time series were recorded in 30 male adults with an autism spectrum condition (ASC) and 33 age- and IQ-matched male volunteers. The Hurst exponent was estimated in the wavelet domain and between-group differences were investigated at global and voxel level and in regions known to be involved in autism. Complex fractal scaling of fMRI time series was found in both groups but globally there was a significant shift to randomness in the ASC (mean H = .758, SD = .045) compared with neurotypical volunteers (mean H = .788, SD = .047). Between-group differences in H, which was always reduced in the ASC group, were seen in most regions previously reported to be involved in autism, including cortical midline structures, medial temporal structures, lateral temporal and parietal structures, insula, amygdala, basal ganglia, thalamus, and inferior frontal gyrus. Severity of autistic symptoms was negatively correlated with H in retrosplenial and right anterior insular cortex. Autism is associated with a small but significant shift to randomness of endogenous brain oscillations. Complexity measures may provide physiological indicators for autism as they have done for other medical conditions. Copyright © 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
Huang, Wei-Chang; Wu, Pi-Chu; Chen, Chao-Jung; Cheng, Ya-Hua; Shih, Sou-Jen; Chen, Hui-Chen; Wu, Chieh-Liang
2016-05-01
Patients with prolonged mechanical ventilation (PMV) often retain airway secretions, which may be cleared with the assistance of high-frequency chest wall oscillation (HFCWO). This study aimed to determine the effectiveness, safety and tolerance/comfort of HFCWO after extubation in PMV patients. This parallel-designed, randomized controlled trial enrolled subjects with both intra-tracheal intubation and mechanical ventilator support continuously for at least 21 days between January 2011 and December 2012. Upon extubation, the participants were randomly assigned to either receive HFCWO for 5 days or not. The effectiveness [based on weaning success rates, daily clearance volume of sputum, serial changes in sputum coloration and chest X-ray (CXR) improvement rates], safety (by physiologic parameters) and tolerance/comfort [using the Modified Borg Scale (MBS) and Hamilton Anxiety Scale (HAS)] of HFCWO were investigated. There were 43 PMV subjects, including 23 in the HFCWO group and 20 in the non-HFCWO group. The weaning success rates were 82.6% (19/23) and 85% (17/20) in the HFCWO and non-HFCWO groups, respectively (P = 1.000). The HFCWO group had persistently greater numbers of daily sputum suctions and higher CXR improvement rates compared with the non-HFCWO group. There was significant sputum coloration lightening in the HFCWO group only. There was no significant difference in the MBS and HAS between the two groups and between pre- and post-HFCWO physiologic parameters. In PMV patients, HFCWO was safe, comfortable and effective in facilitating airway hygiene after removal of endotracheal tubes, but had no positive impact on weaning success. © 2014 John Wiley & Sons Ltd.
Energy Technology Data Exchange (ETDEWEB)
Grassi, A., E-mail: agrassi@unict.it [Dipartimento di Scienze del Farmaco, v.le A. Doria 6, Università di Catania, 95125 Catania (Italy); Lombardo, G.M. [Dipartimento di Scienze del Farmaco, v.le A. Doria 6, Università di Catania, 95125 Catania (Italy); Pannuzzo, M., E-mail: martina.pannuzzo@gmail.com [Department of Computational Biology, University of Erlangen-Nuremberg, Staudtstrasse 5, 91058 Erlangen (Germany); Raudino, A., E-mail: araudino@dipchi.unict.it [Dipartimento di Scienze Chimiche, v.le A. Doria 6, Università di Catania, 95125 Catania (Italy)
2015-02-06
Highlights: • We analyzed the particles dynamics subject to an oscillating “trap”. • Numerical solution to FPE with various trap's oscillating frequencies and amplitudes. • Out-of-equilibrium calculations describe the evolution toward a “pseudo” equilibrium state. • At pseudo-equilibrium state trapped particles density depends on frequency and amplitude. - Abstract: We investigated the time evolution of a distribution of random diffusing particles around an oscillating non-ideal trap. The problem has been addressed by numerically solving a mono-dimensional Fokker–Planck equation (FPE) for a confined distribution of particles in the presence of an oscillating potential well (trap) of finite depth. Accurate numerical solutions of the FPE have been obtained and expressed as a function of the trap oscillation amplitudes and frequencies. Results show a marked influence of the oscillations both on the capture kinetics and trap efficiency in equilibrium conditions. All the calculated properties exhibit a saturation behavior both at high and low frequencies.
2013-01-01
Background Ultrasonic bone-cutting surgery has been introduced as a feasible alternative to the conventional sharp instruments used in craniomaxillofacial surgery because of its precision and safety. The piezosurgery medical device allows the efficient cutting of mineralized tissues with minimal trauma to soft tissues. Piezoelectric osteotome has found its role in surgically assisted rapid maxillary expansion (SARME), a procedure well established to correct transverse maxillary discrepancies. The advantages include minimal risk to critical anatomic structures. The purpose of this clinical comparative study (CIS 2007-237-M) was to present the advantages of the piezoelectric cut as a minimally invasive device in surgically assisted, rapid maxillary expansion by protecting the maxillary sinus mucosal lining. Methods Thirty patients (18 females and 12 males) at the age of 18 to 54 underwent a surgically assisted palatal expansion of the maxilla with a combined orthodontic and surgical approach. The patients were randomly divided into two separate treatment groups. While Group 1 received conventional surgery using an oscillating saw, Group 2 was treated with piezosurgery. The following parameters were examined: blood pressure, blood values, required medication, bleeding level in the maxillary sinus, duration of inpatient stay, duration of surgery and height of body temperature. Results The results displayed no statistically significant differences between the two groups regarding laboratory blood values and inpatient stay. The duration of surgery revealed a significant discrepancy. Deploying piezosurgery took the surgeon an average of 10 minutes longer than working with a conventional-saw technique. However, the observation of the bleeding level in the paranasal sinus presented a major and statistically significant advantage of piezosurgery: on average the bleeding level was one category above the one of the remaining patients. Conclusion This method of piezoelectric
Chuang, Ming-Lung; Chou, Yi-Ling; Lee, Chai-Yuan; Huang, Shih-Feng
2017-03-01
Endotracheal intubation and prolonged immobilization of patients receiving mechanical ventilation may reduce expectoration function. High-frequency chest wall oscillation (HFCWO) may ameliorate airway secretion movement; however, the instantaneous changes in patients' cardiopulmonary responses are unknown. Moreover, HFCWO may influence ventilator settings by the vigorous oscillation. The aim of this study was to investigate these issues. Seventy-three patients (52 men) aged 71.5 ± 13.4 years who were intubated with mechanical ventilation for pneumonic respiratory failure were recruited and randomly classified into 2 groups (HFCWO group, n = 36; and control group who received conventional chest physical therapy (CCPT, n = 37). HFCWO was applied with a fixed protocol, whereas CCPT was conducted using standard protocols. Both groups received sputum suction after the procedure. Changes in ventilator settings and the subjects' responses were measured at preset intervals and compared within groups and between groups. Oscillation did not affect the ventilator settings (all P > 0.05). The mean airway pressure, breathing frequency, and rapid shallow breathing index increased, and the tidal volume and SpO2 decreased (all P ventilation decreased (all P ventilator settings, whereas CCPT maintains a steadier condition. After sputum suction, HFCWO slightly improved Ppeak compared to CCPT, suggesting that the study extends the indications of HFCWO for these patients in intensive care unit. (ClinicalTrials.gov number NCT02758106, retrospectively registered.).
Klukowska, M; Grender, J M; Conde, E; Ccahuana-Vasquez, Renzo Alberto; Goyal, C R
2014-01-01
To evaluate the efficacy of a marketed oscillating-rotating (O-R) power toothbrush (Oral-B Triumph with SmartGuide and FlossAction brush head, D34/EB25) to a new sonic toothbrush (Sonicare FlexCare Platinum) in the reduction of gingivitis and plaque over a 12-week test period. This was a single center, randomized, open label, examiner-blind, two-treatment, parallel group study. Subjects who met the entrance criteria were enrolled in the study and randomly assigned to either the O-R or sonic treatment group. Subjects brushed with their assigned toothbrush and a marketed fluoride dentifrice for two minutes twice daily at home for 12 weeks. Gingivitis and plaque were evaluated at Baseline, Week 6, and Week 12. Gingivitis was assessed using the Modified Gingival Index (MGI) and Gingival Bleeding Index (GBI), and plaque was assessed using the Rustogi Modified Navy Plaque Index (RMNPI). Data were analyzed using an Analysis of Covariance (ANCOVA) with Baseline as the covariate. In total, 130 subjects (65 per group) were randomized to treatment and 127 subjects completed the study. Both brushes produced statistically significant (p gingivitis and plaque measures relative to Baseline. At Week 12, the O-R brush demonstrated significantly greater reductions than the sonic brush in whole mouth gingivitis measures (p = 0.007). Additionally, the O-R brush presented significantly fewer bleeding sites (p gingivitis, 19.8% for number of bleeding sites, and 12.2% for whole mouth plaque. There were no adverse events reported or observed for either brush. The oscillating-rotating toothbrush demonstrated statistically significantly greater reductions in whole mouth plaque at Weeks 6 and 12, as well as significantly greater gingivitis reductions over the long-term (12 weeks), compared to the new sonic toothbrush.
Santra, Siddhartha; Cruikshank, Benjamin; Balu, Radhakrishnan; Jacobs, Kurt
2017-10-01
Fermi’s golden rule applies to a situation in which a single quantum state \\vert \\psi> is coupled to a near-continuum. This ‘quasi-continuum coupling’ structure results in a rate equation for the population of \\vert \\psi> . Here we show that the coupling of a quantum system to the standard model of a thermal environment, a bath of harmonic oscillators, can be decomposed into a ‘cascade’ made up of the quasi-continuum coupling structures of Fermi’s golden rule. This clarifies the connection between the physics of the golden rule and that of a thermal bath, and provides a non-rigorous but physically intuitive derivation of the Markovian master equation directly from the former. The exact solution to the Hamiltonian of the golden rule, known as the Bixon-Jortner model, generalized for an asymmetric spectrum, provides a window on how the evolution induced by the bath deviates from the master equation as one moves outside the Markovian regime. Our analysis also reveals the relationship between the oscillator bath and the ‘random matrix model’ (RMT) of a thermal bath. We show that the cascade structure is the one essential difference between the two models, and the lack of it prevents the RMT from generating transition rates that are independent of the initial state of the system. We suggest that the cascade structure is one of the generic elements of thermalizing many-body systems.
Directory of Open Access Journals (Sweden)
Jieun Cho, Kyeongbong Lee, Minkyu Kim, Joohee Hahn, Wanhee Lee
2018-03-01
Full Text Available This study aimed to investigate the effect of double oscillation exercise combined with elastic band exercise on the strength and thickness ratio of the scapular stabilizing muscles in healthy young individuals. A total of 30 subjects (17 male, 13 female were randomly assigned to an elastic band exercise group (EBG (n = 15 or an elastic band plus double oscillation exercise group (EB-DOG (n = 15. A total of 28 subjects completed the experiment and evaluation. Patients in the EBG performed the elastic band exercise for shoulder flexion, extension, abduction, adduction, horizontal abduction/adduction, and internal/external rotation for 30 minutes/session, five times/week, for four weeks. Patients in the EB-DOG performed the elastic band exercise for 15 minutes and the double oscillation exercise in three planes of motion (frontal, sagittal, and transverse, using a Bodyblade® for 15 minutes/session, five times/week, for four weeks. Shoulder muscle strength was assessed using a manual muscle test device during maximal voluntary isometric contraction (MVIC, while the thicknesses of the scapular stabilizing muscles were assessed using rehabilitative ultrasound imaging both at rest and during MVIC. Both groups had significant effects on shoulder muscle strength, however, there was no significant difference between the two groups for change value of shoulder muscle strength (Bonferroni correction p < 0.005. Significant differences were observed in the group × time interactions for horizontal abduction, external rotation, and protraction. There was a statistically significant improvement in thickness ratio of LT and SA in the EB-DOG and no significant difference was founded in EBG (Bonferroni correction p < 0.006. In comparison between the two groups, EB-DOG showed a significant change in the thickness ratio of LT compared to EBG. In addition, significant differences were observed for the group × time interactions for the thickness ratio of the LT (F
Espinosa, Ismael; Gonzalez, Hortensia; Quiza, Jorge; Gonazalez, J. Jesus; Arroyo, Ruben; Lara, Ritaluz
1995-01-01
Oscillation of electrical activity has been found in many nervous systems, from invertebrates to vertebrates including man. There exists experimental evidence of very simple circuits with the capability of oscillation. Neurons with intrinsic oscillation have been found and also neural circuits where oscillation is a property of the network. These two types of oscillations coexist in many instances. It is nowadays hypothesized that behind synchronization and oscillation there is a system of coupled oscillators responsible for activities that range from locomotion and feature binding in vision to control of sleep and circadian rhythms. The huge knowledge that has been acquired on oscillators from the times of Lord Rayleigh has made the simulation of neural oscillators a very active endeavor. This has been enhanced with more recent physiological findings about small neural circuits by means of intracellular and extracellular recordings as well as imaging methods. The future of this interdisciplinary field looks very promising; some researchers are going into quantum mechanics with the idea of trying to provide a quantum description of the brain. In this work we describe some simulations using neuron models by means of which we form simple neural networks that have the capability of oscillation. We analyze the oscillatory activity with root locus method, cross-correlation histograms, and phase planes. In the more complicated neural network models there is the possibility of chaotic oscillatory activity and we study that by means of Lyapunov exponents. The companion paper shows an example of that kind.
Relaxation damping in oscillating contacts.
Popov, M; Popov, V L; Pohrt, R
2015-11-09
If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect "relaxation damping". The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed.
Directory of Open Access Journals (Sweden)
van den Hout Lieke
2011-11-01
Full Text Available Abstract Background Congenital diaphragmatic hernia (CDH is a severe congenital anomaly of the diaphragm resulting in pulmonary hypoplasia and pulmonary hypertension. It is associated with a high risk of mortality and pulmonary morbidity. Previous retrospective studies have reported high frequency oscillatory ventilation (HFO to reduce pulmonary morbidity in infants with CDH, while others indicated HFO to be associated with worse outcome. We therefore aimed to develop a randomized controlled trial to compare initial ventilatory treatment with high-frequency oscillation and conventional ventilation in infants with CDH. Methods/design This trial is designed as a multicentre trial in which 400 infants (200 in each arm will be included. Primary outcome measures are BPD, described as oxygen dependency by day 28 according to the definition of Jobe and Bancalari, and/or mortality by day 28. All liveborn infants with CDH born at a gestational age of over 34 weeks and no other severe congenital anomalies are eligible for inclusion. Parental informed consent is asked antenatally and the allocated ventilation mode starts within two hours after birth. Laboratory samples of blood, urine and tracheal aspirate are taken at the first day of life, day 3, day 7, day 14 and day 28 to evaluate laboratory markers for ventilator-induced lung injury and pulmonary hypertension. Discussion To date, randomized clinical trials are lacking in the field of CDH. The VICI-trial, as the first randomized clinical trial in the field of CDH, may provide further insight in ventilation strategies in CDH patient. This may hopefully prevent mortality and morbidity. Trial registration Netherlands Trial Register (NTR: NTR1310
Blaise, Paul
2011-01-01
An invaluable reference for an overall but simple approach to the complexity of quantum mechanics viewed through quantum oscillators Quantum oscillators play a fundamental role in many areas of physics; for instance, in chemical physics with molecular normal modes, in solid state physics with phonons, and in quantum theory of light with photons. Quantum Oscillators is a timely and visionary book which presents these intricate topics, broadly covering the properties of quantum oscillators which are usually dispersed in the literature at varying levels of detail and often combined with other p
Indian Academy of Sciences (India)
processes at the cellular level like the glycolytic pathway, peroxi- dase-catalysed reaction or the biosynthesis of certain proteins. A systematic study of oscillating chemical reactions is of consider- able interest, since these oscillating reactions can be used as prototype examples of the behaviours possible in reactions gov-.
Friedel oscillations in graphene
DEFF Research Database (Denmark)
Lawlor, J. A.; Power, S. R.; Ferreira, M.S.
2013-01-01
Symmetry breaking perturbations in an electronically conducting medium are known to produce Friedel oscillations in various physical quantities of an otherwise pristine material. Here we show in a mathematically transparent fashion that Friedel oscillations in graphene have a strong sublattice...... asymmetry. As a result, the presence of impurities and/or defects may impact the distinct graphene sublattices very differently. Furthermore, such an asymmetry can be used to explain the recent observations that nitrogen atoms and dimers are not randomly distributed in graphene but prefer to occupy one...
Energy Technology Data Exchange (ETDEWEB)
Arik, M. (Istanbul Technical Univ. (Turkey). Dept. of Mathematics Bogazici Univ., Istanbul (Turkey). Dept. of Physics); Demircan, E.; Turgut, T. (Texas Univ., Austin, TX (United States). Dept. of Physics); Ekinci, L.; Mungan, M. (Bogazici Univ., Istanbul (Turkey). Dept. of Physics)
1992-07-01
We discuss the properties of oscillators whose spectrum is given by a generalized Fibonacci sequence. The properties include: Invariance under the unitary quantum group, generalized angular momentum, coherent states and difference calculus, relativistic interpretation. (orig.).
Directory of Open Access Journals (Sweden)
Iñigo Arregui
2012-04-01
Full Text Available Prominences are intriguing, but poorly understood, magnetic structures of the solar corona. The dynamics of solar prominences has been the subject of a large number of studies, and of particular interest is the study of prominence oscillations. Ground- and space-based observations have confirmed the presence of oscillatory motions in prominences and they have been interpreted in terms of magnetohydrodynamic (MHD waves. This interpretation opens the door to perform prominence seismology, whose main aim is to determine physical parameters in magnetic and plasma structures (prominences that are difficult to measure by direct means. Here, we review the observational information gathered about prominence oscillations as well as the theoretical models developed to interpret small amplitude oscillations and their temporal and spatial attenuation. Finally, several prominence seismology applications are presented.
Rutten, R.J.
1999-01-01
This review concentrates on the quiet-Sun chromosphere. Its internetwork areas are dynamically dominated by the so-called chromospheric three-minute oscillation. They are interpretationally dominated by the so-called Ca II K 2V and H 2V grains. The main points of this review are that the one
Energy Technology Data Exchange (ETDEWEB)
George Neil
2003-05-12
FEL Oscillators have been around since 1977 providing not only a test bed for the physics of Free Electron Lasers and electron/photon interactions but as a workhorse of scientific research. More than 30 FEL oscillators are presently operating around the world spanning a wavelength range from the mm region to the ultraviolet using DC and rf linear accelerators and storage rings as electron sources. The characteristics that have driven the development of these sources are the desire for high peak and average power, high micropulse energies, wavelength tunability, timing flexibility, and wavelengths that are unavailable from more conventional laser sources. Substantial user programs have been performed using such sources encompassing medicine, biology, solid state research, atomic and molecular physics, effects of non-linear fields, surface science, polymer science, pulsed laser vapor deposition, to name just a few.
Klukowska, Malgorzata; Grender, Julie M; Conde, Erinn; Ccahuana-Vasquez, Renzo Alberto; Ram Goyal, C
2014-08-01
To compare the efficacy of an oscillating-rotating power toothbrush with a novel brush head incorporating angled CrissCross bristles (Oral-B Pro 7000 SmartSeries and Oral-B CrossAction brush head) versus a marketed sonic toothbrush (Colgate ProClinical A1500 with the Triple Clean brush head) in the reduction of gingivitis and plaque over a 6-week period. This was a single center, randomized, open label, examiner-blind, 2-treatment, parallel group study. Study participants who met the entrance criteria were enrolled in the study and randomly assigned to one of the two toothbrush groups. Study participants brushed with their assigned toothbrush and a marketed fluoride dentifrice for 2 minutes twice daily at home for 6 weeks. Gingivitis and plaque were evaluated at baseline and Week 6. Gingivitis was assessed using the Modified Gingival Index (MGI) and Gingival Bleeding Index (GBI) and plaque was assessed using the Rustogi Modified Navy Plaque Index (RMNPI). Data was analyzed using the ANCOVA with baseline as the covariate. In total, 130 study participants were randomized to treatment resulting in 64 study participants per group completing the study. Both brushes produced statistically significant (P gingivitis and plaque measures relative to baseline. The oscillating-rotating,brush with the novel brush head demonstrated statistically significantly (P gingivitis measures, as well as whole mouth and interproximal plaque measures, compared to the sonic toothbrush. The benefit for the oscillating- rotating brush over the sonic brush was 21.3% for gingivitis, 35.7% for gingival bleeding, 34.7% for number of bleeding sites, 17.4% for whole mouth plaque, and 21.2% for interproximal plaque. There were no adverse events reported or observed for either brush.
DEFF Research Database (Denmark)
Lindberg, Erik
1997-01-01
In order to obtain insight in the nature of nonlinear oscillators the eigenvalues of the linearized Jacobian of the differential equations describing the oscillator are found and displayed as functions of time. A number of oscillators are studied including Dewey's oscillator (piecewise linear wit...... with negative resistance), Kennedy's Colpitts-oscillator (with and without chaos) and a new 4'th order oscillator with hyper-chaos.......In order to obtain insight in the nature of nonlinear oscillators the eigenvalues of the linearized Jacobian of the differential equations describing the oscillator are found and displayed as functions of time. A number of oscillators are studied including Dewey's oscillator (piecewise linear...
Characterizing correlations of flow oscillations at bottlenecks
Kretz, Tobias; Woelki, Marko; Schreckenberg, Michael
2006-01-01
"Oscillations" occur in quite different kinds of many-particle-systems when two groups of particles with different directions of motion meet or intersect at a certain spot. We present a model of pedestrian motion that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis' correlated random walk are shown to hold observables that can be used to characterize different kinds of oscillations.
Characterizing correlations of flow oscillations at bottlenecks
Kretz, Tobias; Wölki, Marko; Schreckenberg, Michael
2006-02-01
'Oscillations' occur in quite different kinds of many-particle systems when two groups of particles with different directions of motion meet or intersect at a certain spot. In this work a model of pedestrian motion is presented that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis' correlated random walk are shown to include observables that can be used to characterize different kinds of oscillations.
Graf, Rudolf F
1996-01-01
This series of circuits provides designers with a quick source for oscillator circuits. Why waste time paging through huge encyclopedias when you can choose the topic you need and select any of the specialized circuits sorted by application?This book in the series has 250-300 practical, ready-to-use circuit designs, with schematics and brief explanations of circuit operation. The original source for each circuit is listed in an appendix, making it easy to obtain additional information.Ready-to-use circuits.Grouped by application for easy look-up.Circuit source listing
Power oscillation damping controller
DEFF Research Database (Denmark)
2012-01-01
A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control...... signal in response to the oscillation indicating signal, by processing the oscillation damping control signal in a signal processing chain. The signal processing chain includes a filter configured for passing only signals within a predetermined frequency range....
Sahlem, Gregory L; Badran, Bashar W; Halford, Jonathan J; Williams, Nolan R; Korte, Jeffrey E; Leslie, Kimberly; Strachan, Martha; Breedlove, Jesse L; Runion, Jennifer; Bachman, David L; Uhde, Thomas W; Borckardt, Jeffery J; George, Mark S
2015-01-01
A 2006 trial in healthy medical students found that anodal slow oscillating tDCS delivered bi-frontally during slow wave sleep had an enhancing effect in declarative, but not procedural memory. Although there have been supporting animal studies, and similar findings in pathological groups, this study has not been replicated, or refuted, in the intervening years. We therefore tested these earlier results for replication using similar methods with the exception of current waveform (square in our study, nearly sinusoidal in the original). Our objective was to test the findings of a 2006 trial suggesting bi-frontal anodal tDCS during slow wave sleep enhances declarative memory. Twelve students (mean age 25, 9 women) free of medical problems underwent two testing conditions (active, sham) in a randomized counterbalanced fashion. Active stimulation consisted of oscillating square wave tDCS delivered during early Non-Rapid Eye Movement (NREM) sleep. The sham condition consisted of setting-up the tDCS device and electrodes, but not turning it on during sleep. tDCS was delivered bi-frontally with anodes placed at F3/F4, and cathodes placed at mastoids. Current density was 0.517 mA/cm(2), and oscillated between zero and maximal current at a frequency of 0.75 Hz. Stimulation occurred during five-five minute blocks with 1-min inter-block intervals (25 min total stimulation). The primary outcomes were both declarative memory consolidation measured by a paired word association test (PWA), and non-declarative memory, measured by a non-dominant finger-tapping test (FTT). We also recorded and analyzed sleep EEG. There was no difference in the number of paired word associations remembered before compared to after sleep [(active = 3.1 ± 3.0 SD more associations) (sham = 3.8 ± 3.1 SD more associations)]. Finger tapping improved, (non-significantly) following active stimulation [(3.6 ± 2.7 SD correctly typed sequences) compared to sham stimulation (2.3 ± 2.2 SD correctly typed
Brownian motion with adhesion: harmonic oscillator with fluctuating mass.
Gitterman, M; Klyatskin, V I
2010-05-01
In contrast to the cases usually studied of a harmonic oscillator subject to a random force (Brownian motion) or having random frequency or random damping, we consider a random mass which corresponds to an oscillator for which the particles of the surrounding medium adhere to it for some (random) time after the collision, thereby changing the oscillator mass. This model, which describes Brownian motion with adhesion, can be useful for the analysis of chemical and biological solutions as well as nanotechnological devices. We consider dichotomous noise and its limiting case, white noise.
Kleinberg, L. L.
1969-01-01
Microelectronic oscillator uses a bipolar transistor to circumvent the problem of developing suitable inductors for lower frequencies. The oscillator is fabricated by hybrid thin film techniques or by monolithic construction. Discrete microminiature components may also be employed.
Ma, Hongbin
2015-01-01
This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation, theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary factors affecting oscillating motions and heat transfer, neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes. The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, gradua...
Phenomenology of neutrino oscillations
Indian Academy of Sciences (India)
Abstract. The phenomenology of solar, atmospheric, supernova and laboratory neutrino oscillations is described. Analytical formulae for matter effects are reviewed. The results from oscillations are confronted with neutrinoless double beta decay.
Mansingka, Abhinav S.
2014-06-18
This paper introduces fully digital implementations of four di erent systems in the 3rd order jerk-equation based chaotic family using the Euler approximation. The digitization approach enables controllable chaotic systems that reliably provide sinusoidal or chaotic output based on a selection input. New systems are introduced, derived using logical and arithmetic operations between two system implementations of different bus widths, with up to 100x higher maximum Lyapunov exponent than the original jerkequation based chaotic systems. The resulting chaotic output is shown to pass the NIST sp. 800-22 statistical test suite for pseudorandom number generators without post-processing by only eliminating the statistically defective bits. The systems are designed in Verilog HDL and experimentally verified on a Xilinx Virtex 4 FPGA for a maximum throughput of 15.59 Gbits/s for the native chaotic output and 8.77 Gbits/s for the resulting pseudo-random number generators.
Directory of Open Access Journals (Sweden)
Aurore Thibaut
2017-11-01
Full Text Available ObjectiveChronic visceral pain (CVP syndromes are persistently painful disorders with a remarkable lack of effective treatment options. This study aimed at evaluating the effects of different neuromodulation techniques in patients with CVP on cortical activity, through electreocephalography (EEG and on pain perception, through clinical tests.DesignA pilot crossover randomized controlled study.SettingsOut-patient.SubjectsAdults with CVP (>3 months.MethodsParticipants received four interventions in a randomized order: (1 transcranial pulsed current stimulation (tPCS and active transcranial direct current stimulation (tDCS combined, (2 tPCS alone, (3 tDCS alone, and (4 sham condition. Resting state quantitative electroencephalography (qEEG and pain assessments were performed before and after each intervention. Results were compared with a cohort of 47 healthy controls.ResultsWe enrolled six patients with CVP for a total of 21 visits completed. Compared with healthy participants, patients with CVP showed altered cortical activity characterized by increased power in theta, alpha and beta bands, and a significant reduction in the alpha/beta ratio. Regarding tES, the combination of tDCS with tPCS had no effect on power in any of the bandwidths, nor brain regions. Comparing tPCS with tDCS alone, we found that tPCS induced higher increase in power within the theta and alpha bandwidths.ConclusionThis study confirms that patients with CVP present abnormal EEG-indexed cortical activity compared with healthy controls. Moreover, we showed that combining two types of neurostimulation techniques had no effect, whereas the two interventions, when applied individually, have different neural signatures.
The colpitts oscillator family
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
A tutorial study of the Colpitts oscillator family defined as all oscillators based on a nonlinear amplifier and a three- terminal linear resonance circuit with one coil and two capacitors. The original patents are investigated. The eigenvalues of the linearized Jacobian for oscillators based...
Nature's Autonomous Oscillators
Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.
2012-01-01
Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.
A memristor-based third-order oscillator: beyond oscillation
Talukdar, A.; Radwan, A. G.; Salama, K. N.
2011-09-01
This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.
A memristor-based third-order oscillator: beyond oscillation
Talukdar, Abdul Hafiz Ibne
2012-10-06
This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.
Kato, Shoji
2016-01-01
This book presents the current state of research on disk oscillation theory, focusing on relativistic disks and tidally deformed disks. Since the launch of the Rossi X-ray Timing Explorer (RXTE) in 1996, many high-frequency quasiperiodic oscillations (HFQPOs) have been observed in X-ray binaries. Subsequently, similar quasi-periodic oscillations have been found in such relativistic objects as microquasars, ultra-luminous X-ray sources, and galactic nuclei. One of the most promising explanations of their origin is based on oscillations in relativistic disks, and a new field called discoseismology is currently developing. After reviewing observational aspects, the book presents the basic characteristics of disk oscillations, especially focusing on those in relativistic disks. Relativistic disks are essentially different from Newtonian disks in terms of several basic characteristics of their disk oscillations, including the radial distributions of epicyclic frequencies. In order to understand the basic processes...
General Forced Oscillations in a Real Power Grid Integrated with Large Scale Wind Power
Directory of Open Access Journals (Sweden)
Ping Ju
2016-07-01
Full Text Available According to the monitoring of the wide area measurement system, inter-area oscillations happen more and more frequently in a real power grid of China, which are close to the forced oscillation. Applying the conventional forced oscillation theory, the mechanism of these oscillations cannot be explained well, because the oscillations vary with random amplitude and a narrow frequency band. To explain the mechanism of such oscillations, the general forced oscillation (GFO mechanism is taken into consideration. The GFO is the power system oscillation excited by the random excitations, such as power fluctuations from renewable power generation. Firstly, properties of the oscillations observed in the real power grid are analyzed. Using the GFO mechanism, the observed oscillations seem to be the GFO caused by some random excitation. Then the variation of the wind power measured in this power gird is found to be the random excitation which may cause the GFO phenomenon. Finally, simulations are carried out and the power spectral density of the simulated oscillation is compared to that of the observed oscillation, and they are similar with each other. The observed oscillation is thus explained well using the GFO mechanism and the GFO phenomenon has now been observed for the first time in real power grids.
Dependence of synchronization frequency of Kuramoto oscillators ...
Indian Academy of Sciences (India)
matically by Wiener [7,8]. He realized the ubiquity of the phenomenon and speculated its involvement in the generation of alpha rhythms in the brain. ..... [6] Y Kuramoto, Chemical oscillations, waves, and turbulence (Dover Publications, Mineola,. New York, 2003). [7] N Wiener, Nonlinear problem in random theory edited by ...
Synchronization of oscillators in complex networks
Indian Academy of Sciences (India)
Theory of identical or complete synchronization of identical oscillators in arbitrary networks is introduced. In addition, several graph theory concepts and results that augment the synchronization theory and a tie in closely to random, semirandom, and regular networks are introduced. Combined theories are used to explore ...
The Oscillator Principle of Nature
DEFF Research Database (Denmark)
Lindberg, Erik
2012-01-01
Oscillators are found on all levels in Nature. The general oscillator concept is defined and investigated. Oscillators may synchronize into fractal patterns. Apparently oscillators are the basic principle in Nature. The concepts of zero and infinite are discussed. Electronic manmade oscillators...
DEFF Research Database (Denmark)
Hjorth, Poul G.
2008-01-01
We discuss nonlinear mechanical systems containing several oscillators whose frequecies are all much higher than frequencies associated with the remaining degrees of freedom. In this situation a near constant of the motion, an adiabatic invariant, exists which is the sum of all the oscillator...
Hyperchaotic Oscillator with Gyrators
DEFF Research Database (Denmark)
Tamasevicius, A; Cenys, A; Mykolaitis, G.
1997-01-01
A fourth-order hyperchaotic oscillator is described. It contains a negative impedance converter, two gyratots, two capacitors and a diode. The dynamics of the oscillator is shown to be characterised by two positive Lyapunov exponents. The performance of the circuit is investigated by means...
Weger, J.G.; Water, van de W.; Molenaar, J.
2000-01-01
An impact oscillator is a periodically driven system that hits a wall when its amplitude exceeds a critical value. We study impact oscillations where collisions with the wall are with near-zero velocity (grazing impacts). A characteristic feature of grazing impact dynamics is a geometrically
Synchronization of hyperchaotic oscillators
DEFF Research Database (Denmark)
Tamasevicius, A.; Cenys, A.; Mykolaitis, G.
1997-01-01
Synchronization of chaotic oscillators is believed to have promising applications in secure communications. Hyperchaotic systems with multiple positive Lyapunov exponents (LEs) have an advantage over common chaotic systems with only one positive LE. Three different types of hyperchaotic electronic...... oscillators are investigated demonstrating synchronization by means of only one properly selected variable....
Prediction of resonant oscillation
DEFF Research Database (Denmark)
2010-01-01
oscillations and compare the measured oscillations using FFT analysis of signal correlations, variance analysis of signals and other comparisons. As an example, the presence of a growing peak around a frequency that doubles the roll natural frequency indicates the possibility that parametric roll is going...
Magnetostatic wave oscillator frequencies
Sethares, J. C.; Stiglitz, M. R.; Weinberg, I. J.
1981-03-01
The frequencies of magnetostatic wave (MSW) oscillators employing three principal modes of propagation, surface (MSSW), forward (MSFVW), and backward (MSBVW) volume waves, have been investigated. Previous (MSW) oscillator papers dealt with MSSW. Oscillators were fabricated using LPE-YIG MSW delay lines in a feedback loop of a 2-4 GHz amplifier. Wide and narrow band transducers were employed. Oscillator frequency as a function of biasing field is in agreement with a theoretical analysis. The analysis predicts frequency in terms of material parameters, biasing field, and transducer geometry. With wide band transducers a comb of frequencies is generated. Narrow band transducers for MSSW and MSFVW select a single mode; and MSBVW selects two modes. Spurious modes, attributed to instrumentation, are more than 20 dB below the main response, and bandwidths are less than 0.005 percent. No other spurious modes are observed. MSW oscillators produce clean electronically tunable signals and appear attractive in frequency agile systems.
pH-regulated chemical oscillators.
Orbán, Miklós; Kurin-Csörgei, Krisztina; Epstein, Irving R
2015-03-17
The hydrogen ion is arguably the most ubiquitous and important species in chemistry. It also plays a key role in nearly every biological process. In this Account, we discuss systems whose behavior is governed by oscillations in the concentration of hydrogen ion. The first chemical oscillators driven by changes in pH were developed a quarter century ago. Since then, about two dozen new pH oscillators, systems in which the periodic variation in pH is not just an indicator but an essential prerequisite of the oscillatory behavior, have been discovered. Mechanistic understanding of their behavior has grown, and new ideas for their practical application have been proposed and, in some cases, tested. Here we present a catalog of the known pH oscillators, divide them into mechanistically based categories based on whether they involve a single oxidant and reductant or an oxidant and a pair of reductants, and describe general mechanisms for these two major classes of systems. We also describe in detail the chemistry of one example from each class, hydrogen peroxide-sulfide and ferricyanide-iodate-sulfite. Finally, we consider actual and potential applications. These include using pH oscillators to induce oscillation in species that would otherwise be nonoscillatory, creating novel spatial patterns, generating periodic transitions between vesicle and micelle states, stimulating switching between folded and random coil states of DNA, building molecular motors, and designing pulsating drug delivery systems. We point out the importance for future applications of finding a batch pH oscillator, one that oscillates in a closed system for an extended period of time, and comment on the progress that has been made toward that goal.
Amplitude death and resurgence of oscillation in networks of mobile oscillators
Majhi, Soumen; Ghosh, Dibakar
2017-05-01
The phenomenon of amplitude death has been explored using a variety of different coupling strategies in the last two decades. In most of the works, the basic coupling arrangement is considered to be static over time, although many realistic systems exhibit significant changes in the interaction pattern as time varies. In this article, we study the emergence of amplitude death in a dynamical network composed of time-varying interaction amidst a collection of random walkers in a finite region of three-dimensional space. We consider an oscillator for each walker and demonstrate that depending upon the network parameters and hence the interaction between them, the global oscillation in the network gets suppressed. In this framework, the vision range of each oscillator decides the number of oscillators with which it interacts. In addition, with the use of an appropriate feedback parameter in the coupling strategy, we articulate how the suppressed oscillation can be resurrected in the systems' parameter space. The phenomenon of amplitude death and the resurgence of oscillation is investigated taking limit cycle and chaotic oscillators for broad ranges of the parameters, like the interaction strength k between the entities, the vision range r and the speed of movement v.
Time Series Decomposition into Oscillation Components and Phase Estimation.
Matsuda, Takeru; Komaki, Fumiyasu
2017-02-01
Many time series are naturally considered as a superposition of several oscillation components. For example, electroencephalogram (EEG) time series include oscillation components such as alpha, beta, and gamma. We propose a method for decomposing time series into such oscillation components using state-space models. Based on the concept of random frequency modulation, gaussian linear state-space models for oscillation components are developed. In this model, the frequency of an oscillator fluctuates by noise. Time series decomposition is accomplished by this model like the Bayesian seasonal adjustment method. Since the model parameters are estimated from data by the empirical Bayes' method, the amplitudes and the frequencies of oscillation components are determined in a data-driven manner. Also, the appropriate number of oscillation components is determined with the Akaike information criterion (AIC). In this way, the proposed method provides a natural decomposition of the given time series into oscillation components. In neuroscience, the phase of neural time series plays an important role in neural information processing. The proposed method can be used to estimate the phase of each oscillation component and has several advantages over a conventional method based on the Hilbert transform. Thus, the proposed method enables an investigation of the phase dynamics of time series. Numerical results show that the proposed method succeeds in extracting intermittent oscillations like ripples and detecting the phase reset phenomena. We apply the proposed method to real data from various fields such as astronomy, ecology, tidology, and neuroscience.
Kayser, Boris
2014-04-10
To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also provide a brief guide to references relevant to topics other than neutrino oscillation that were covered in the lectures.
Simakov, David S. A.; Pérez-Mercader, Juan
2013-08-01
Oscillating chemical reactions are common in biological systems and they also occur in artificial non-biological systems. Generally, these reactions are subject to random fluctuations in environmental conditions which translate into fluctuations in the values of physical variables, for example, temperature. We formulate a mathematical model for a nonisothermal minimal chemical oscillator containing a single negative feedback loop and study numerically the effects of stochastic fluctuations in temperature in the absence of any deterministic limit cycle or periodic forcing. We show that noise in temperature can induce sustained limit cycle oscillations with a relatively narrow frequency distribution and some characteristic frequency. These properties differ significantly depending on the noise correlation. Here, we have explored white and colored (correlated) noise. A plot of the characteristic frequency of the noise induced oscillations as a function of the correlation exponent shows a maximum, therefore indicating the existence of autonomous stochastic resonance, i.e. coherence resonance.
Classical oscillator driven by an oscillating chirped force
Khachatryan, A.G.; van Goor, F.A.; Boller, Klaus J.
2006-01-01
The motion of a classical (harmonic) oscillator is studied in the case where the oscillator is driven by a pulsed oscillating force with a frequency varying in time (frequency chirp). The amplitude and phase of the oscillations left after the pulsed force in dependence on the profile and strength of
High frequency nanotube oscillator
Peng, Haibing [Houston, TX; Zettl, Alexander K [Kensington, TX
2012-02-21
A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.
Neutrino anomalies without oscillations
Indian Academy of Sciences (India)
conventional' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well. Author Affiliations. Sandip Pakvasa1. Department of Physics and Astronomy, University of Hawaii, Honolulu, HI 96822, USA ...
Neural Oscillators Programming Simplified
Directory of Open Access Journals (Sweden)
Patrick McDowell
2012-01-01
Full Text Available The neurological mechanism used for generating rhythmic patterns for functions such as swallowing, walking, and chewing has been modeled computationally by the neural oscillator. It has been widely studied by biologists to model various aspects of organisms and by computer scientists and robotics engineers as a method for controlling and coordinating the gaits of walking robots. Although there has been significant study in this area, it is difficult to find basic guidelines for programming neural oscillators. In this paper, the authors approach neural oscillators from a programmer’s point of view, providing background and examples for developing neural oscillators to generate rhythmic patterns that can be used in biological modeling and robotics applications.
solar neutrino oscillation phenomenology
Indian Academy of Sciences (India)
The sMA region and a large part of the vacuum oscillation region are seen to have been washed away with the inclusion of the sK spectrum data. In the left panel of figure 4 we show the dependence of the probabilities on energy. In the sMA and the VO oscillation regions the probability has a non- monotonic dependence ...
Jenkins, Alejandro
2011-01-01
Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain linear systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy from the environment into the vibration: no external rate needs to be tuned to the resonant frequency. A paper from 1830 by G. B. Airy gives us the opening to introduce self-oscillation as a sort of "perpetual motion" responsible for the human voice. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the more recent swaying of the London Millenium Footbridge. Clocks are self-oscillators, as are bowed and wind musical instruments, and the heartbeat. We review the criterion that determines whether an arbitrary line...
Energy Technology Data Exchange (ETDEWEB)
Hoeye, Gudrun Kristine
1999-07-01
We have studied radial and nonradial oscillations in neutron stars, both in a general relativistic and non-relativistic frame, for several different equilibrium models. Different equations of state were combined, and our results show that it is possible to distinguish between the models based on their oscillation periods. We have particularly focused on the p-, f-, and g-modes. We find oscillation periods of II approx. 0.1 ms for the p-modes, II approx. 0.1 - 0.8 ms for the f-modes and II approx. 10 - 400 ms for the g-modes. For high-order (l (>{sub )} 4) f-modes we were also able to derive a formula that determines II{sub l+1} from II{sub l} and II{sub l-1} to an accuracy of 0.1%. Further, for the radial f-mode we find that the oscillation period goes to infinity as the maximum mass of the star is approached. Both p-, f-, and g-modes are sensitive to changes in the central baryon number density n{sub c}, while the g-modes are also sensitive to variations in the surface temperature. The g-modes are concentrated in the surface layer, while p- and f-modes can be found in all parts of the star. The effects of general relativity were studied, and we find that these are important at high central baryon number densities, especially for the p- and f-modes. General relativistic effects can therefore not be neglected when studying oscillations in neutron stars. We have further developed an improved Cowling approximation in the non-relativistic frame, which eliminates about half of the gap in the oscillation periods that results from use of the ordinary Cowling approximation. We suggest to develop an improved Cowling approximation also in the general relativistic frame. (Author)
Hagedorn, Peter
1982-01-01
Thoroughly revised and updated, the second edition of this concise text provides an engineer's view of non-linear oscillations, explaining the most important phenomena and solution methods. Non-linear descriptions are important because under certain conditions there occur large deviations from the behaviors predicted by linear differential equations. In some cases, completely new phenomena arise that are not possible in purely linear systems. The theory of non-linear oscillations thus has important applications in classical mechanics, electronics, communications, biology, and many other branches of science. In addition to many other changes, this edition has a new section on bifurcation theory, including Hopf's theorem.
Brownian parametric oscillators
Zerbe, Christine; Jung, Peter; Hänggi, Peter
1994-05-01
We discuss the stochastic dynamics of dissipative, white-noise-driven Floquet oscillators, characterized by a time-periodic stiffness. Thus far, little attention has been paid to these exactly solvable nonstationary systems, although they carry a rich potential for several experimental applications. Here, we calculate and discuss the mean values and variances, as well as the correlation functions and the Floquet spectrum. As one main result, we find for certain parameter values that the fluctuations of the position coordinate are suppressed as compared to the equilibrium value of a harmonic oscillator (parametric squeezing).
Image hiding scheme based on time-averaged elliptic oscillations
Saunoriene, Loreta; Aleksiene, Sandra; Maskeliunas, Rimas; Ragulskis, Minvydas
2017-11-01
Image hiding technique based on time-averaged elliptic oscillations is proposed in this paper. The scheme is based on a single cover image representing a cross-moiré grating. The secret image is embedded into the background moiré grating by using a specially developed random scrambling algorithm. The secret is leaked in a form of a pattern of time-averaged moiré fringes when the cover image is elliptically oscillated. Also, the secret is leaked only if the parameters of elliptic oscillations are set to predefined values. Computational experiments are used to validate the proposed technique and to demonstrate the efficiency of its implementation.
Jones, R. T.
1976-01-01
For acoustic tests the violin is driven laterally at the bridge by a small speaker of the type commonly found in pocket transistor radios. An audio oscillator excites the tone which is picked up by a sound level meter. Gross patterns of vibration modes are obtained by the Chladni method.
Oscillators and operational amplifiers
DEFF Research Database (Denmark)
Lindberg, Erik
2005-01-01
A generalized approach to the design of oscillators using operational amplifiers as active elements is presented. A piecewise-linear model of the amplifier is used so that it make sense to investigate the eigenvalues of the Jacobian of the differential equations. The characteristic equation...
Phenomenology of neutrino oscillations
Kobzarev, I Yu; Okun, Lev Borisovich; Shchepkin, M G
1980-01-01
A complete phenomenological description of neutrino oscillations is given. The most general form of the mass matrix of N types of neutrino and of the matrix of neutrino mixing in the left charged current is analyzed. Measuring the parameters of the charged current matrix in oscillatory experiments and in the experimental studies of the beta -decay electron spectra, is discussed. (20 refs).
Neutrino oscillation experiments
Energy Technology Data Exchange (ETDEWEB)
Camilleri, L. [European Organization for Nuclear Research, Geneva (Switzerland)
1996-11-01
Neutrino oscillation experiments ({nu}{sub {mu}}{yields}{nu}{sub e} and {nu}{sub {mu}}{yields}{nu}{sub {tau}}) currently being performed at accelerators are reviewed. Future plans for short and long base-line experiments are summarized. (author) 10 figs., 2 tabs., 29 refs.
Proprioceptive evoked gamma oscillations
DEFF Research Database (Denmark)
Arnfred, Sidse M; Hansen, Lars Kai; Parnas, Josef
2007-01-01
to evoke gamma oscillations. EEG was recorded using 64 channels in 14 healthy subjects. In each of three runs a stimulus of 100 g load increment in each hand was presented in 120 trials. Data were wavelet transformed and runs collapsed. Inter-trial phase coherence (ITPC) was computed as the best measure...
Photonic local oscillator development
Kimberk, Robert; Tong, Edward; Hunter, Todd R.; Christensen, Robert; Blundell, Ray
2006-12-01
In the receiver lab, we have developed a 200 GHz to 230 GHz local oscillator constructed from mostly commercially available 1550 nm laser communication components. Theoretical and experimental work show that the laser adds negligible phase noise to this photonic local oscillator system and that spectral purity and phase stability are similar to Gunn oscillator based local oscillator output. The optical path consists of a single 1550 nm diode laser, a lithium niobate optical phase modulator, a Mach Zehnder interferometer (MZI) with a free spectral range of 75 GHz, and a 160 GHz to 260 GHz photomixer whose output is connected to a horn antenna. All of the optical devices and connections are polarization maintaining, and the photomixer was designed and fabricated at the CCLRC Rutherford Appleton Laboratory. The electrical path consists of a YIG synthesizer, operating in the frequency range 14-20 GHz, a frequency doubler, and a power amplifier connected to the RF port of the phase modulator. At the SMA on Mauna Kea, we incorporated the photonic LO into one element (Antenna 6) of a five antenna array for test observations of CO J=2-1 made towards the ultracompact HII region G138.295+1.555. Spectral features of comparable width occur on baselines with and without antenna 6, and noise increases with baseline length independent of antenna number. Continuum observations were also made toward the quasar 3c454.3 for a period of about one hour. In summary, the SMA has proven that the photonic local oscillator operates with adequate phase and frequency stability for radio-interferometry.
Identifying neuronal oscillations using rhythmicity
Fransen, A.M.M.; Ede, F.L. van; Maris, E.G.G.
2015-01-01
Neuronal oscillations are a characteristic feature of neuronal activity and are typically investigated through measures of power and coherence. However, neither of these measures directly reflects the distinctive feature of oscillations: their rhythmicity. Rhythmicity is the extent to which future
Bimodal oscillations in nephron autoregulation
DEFF Research Database (Denmark)
Sosnovtseva, Olga; Pavlov, A.N.; Mosekilde, Erik
2002-01-01
The individual functional unit of the kidney (the nephron) displays oscillations in its pressure and flow regulation at two different time scales: fast oscillations associated with a myogenic dynamics of the afferent arteriole, and slower oscillations arising from a delay in the tubuloglomerular...
Spectral linewidths of Josephson oscillators
DEFF Research Database (Denmark)
Salerno, M; Samuelsen, Mogens Rugholm; Yulin, AV
2001-01-01
We show that the linewidth of a Josephson flux-flow oscillator has the same functional dependence on temperature, static, and dynamic resistances as the ones of Josephson single-fluxon oscillators and small Josephson junctions. This suggests a universal formula for the linewidth of Josephson...... oscillators....
Nonlinear (Anharmonic Casimir Oscillator
Directory of Open Access Journals (Sweden)
Habibollah Razmi
2011-01-01
Full Text Available We want to study the dynamics of a simple linear harmonic micro spring which is under the influence of the quantum Casimir force/pressure and thus behaves as a (an nonlinear (anharmonic Casimir oscillator. Generally, the equation of motion of this nonlinear micromechanical Casimir oscillator has no exact solvable (analytical solution and the turning point(s of the system has (have no fixed position(s; however, for particular values of the stiffness of the micro spring and at appropriately well-chosen distance scales and conditions, there is (are approximately sinusoidal solution(s for the problem (the variable turning points are collected in a very small interval of positions. This, as a simple and elementary plan, may be useful in controlling the Casimir stiction problem in micromechanical devices.
Entanglement in neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Blasone, M.; Dell' Anno, F.; De Siena, S.; Illuminati, F. [Universita degli Studi di Salerno Via Ponte don Melillon, Dipt. di Matematica e Informatica, Fisciano SA (Italy); INFN Sezione di Napoli, Gruppo collegato di Salerno - Baronissi SA (Italy); Dell' Anno, F.; De Siena, S.; Illuminati, F. [CNR-INFM Coherentia - Napoli (Italy); Blasone, M. [ISI Foundation for Scientific Interchange, Torino (Italy)
2009-03-15
Flavor oscillations in elementary particle physics are related to multimode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We discuss experimental schemes for the transfer of the quantum information encoded in single-neutrino states to spatially delocalized two-flavor charged-lepton states, thus showing, at least in principle, that single-particle entangled states of neutrino mixing are legitimate physical resources for quantum information tasks. (authors)
Acoustics waves and oscillations
Sen, S.N.
2013-01-01
Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...
Convection and stellar oscillations
DEFF Research Database (Denmark)
Aarslev, Magnus Johan
2017-01-01
of stars. For stars like the sun, energy transport in the outer layers occurs mainly through turbulent convection. Here, pressure mode oscillations are essentially propagating sound waves, whose properties can be altered by interaction with the turbulent motion of the gas. This has always been a problem...... for asteroseismology, because of the challenges inherent in modelling turbulent convection in 1D stellar models. As a result of oversimplifying the physics near the surface, theoretical calculations systematically overestimate the oscillation frequencies. This has become known as the asteroseismic surface effect. Due...... to lacking better options, this frequency difference is typically corrected for with ad-hoc formulae. The topic of this thesis is the improvement of 1D stellar convection models and the effects this has on asteroseismic properties. The source of improvements is 3D simulations of radiation...
Proprioceptive evoked gamma oscillations
DEFF Research Database (Denmark)
Arnfred, S.M.; Hansen, Lars Kai; Parnas, J.
2007-01-01
A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...... to evoke gamma oscillations. EEG was recorded using 64 channels in 14 healthy subjects. In each of three runs a stimulus of 100 g load increment in each hand was presented in 120 trials. Data were wavelet transformed and runs collapsed. Inter-trial phase coherence (ITPC) was computed as the best measure...... contralateral to stimulus side and additionally an unexpected 20 Hz activity was observed slightly lateralized in the frontal central region. The gamma phase locking may be a manifestation of early somatosensory feature integration. The analyses suggest that the high frequency activity consists of two distinct...
Neutrino Masses and Oscillations
CERN. Geneva. Audiovisual Unit; Treille, Daniel
2002-01-01
This course will not cover its subject in the customary way. The emphasis will be on the simple theoretical concepts (helicity, handedness, chirality, Majorana masses) which are obscure in most of the literature, and on the quantum mechanics of oscillations, that ALL books get wrong. Which, hopefully, will not deter me from discussing some of the most interesting results from the labs and from the cosmos.
Decay of oscillating universes
Mithani, Audrey Todhunter
2016-08-01
It has been suggested by Ellis et al that the universe could be eternal in the past, without beginning. In their model, the "emergent universe'' exists forever in the past, in an "eternal'' phase before inflation begins. We will show that in general, such an "eternal'' phase is not possible, because of an instability due to quantum tunneling. One candidate model, the "simple harmonic universe'' has been shown by Graham et al to be perturbatively stable; we find that it is unstable with respect to quantum tunneling. We also investigate the stability of a distinct oscillating model in loop quantum cosmology with respect to small perturbations and to quantum collapse. We find that the model has perturbatively stable and unstable solutions, with both types of solutions occupying significant regions of the parameter space. All solutions are unstable with respect to collapse by quantum tunneling to zero size. In addition, we investigate the effect of vacuum corrections, due to the trace anomaly and the Casimir effect, on the stability of an oscillating universe with respect to decay by tunneling to the singularity. We find that these corrections do not generally stabilize an oscillating universe. Finally, we determine the decay rate of the oscillating universe. Although the wave function of the universe lacks explicit time dependence in canonical quantum cosmology, time evolution may be present implicitly through the semiclassical superspace variables, which themselves depend on time in classical dynamics. Here, we apply this approach to the simple harmonic universe, by extending the model to include a massless, minimally coupled scalar field φ which has little effect on the dynamics but can play the role of a "clock''.
Oscillating stagnation point flow
Grosch, C. E.; Salwen, H.
1982-01-01
A solution of the Navier-Stokes equations is given for an incompressible stagnation point flow whose magnitude oscillates in time about a constant, non-zero, value (an unsteady Hiemenz flow). Analytic approximations to the solution in the low and high frequency limits are given and compared with the results of numerical integrations. The application of these results to one aspect of the boundary layer receptivity problem is also discussed.
Oscillations in the Umbral Atmosphere
Brynildsen, N.; Maltby, P.; Foley, C. R.; Fredvik, T.; Kjeldseth-Moe, O.
2004-06-01
The results of simultaneous observations of oscillations in the chromosphere, transition region, and corona above nine sunspots are presented. The data are obtained through coordinated observing with the Solar and Heliospheric Observatory — SOHO and the Transition Region And Coronal Explorer — TRACE. Oscillations are detected above each umbra. The power spectra show one dominant frequency corresponding to a period close to 3 min. We show that the oscillations in the sunspot transition region can be modeled by upwardly propagating acoustic waves. In the corona the oscillations are limited to small regions that often coincide with the endpoints of sunspot coronal loops. Spectral observations show that oscillations in the corona contribute to the observed oscillations in the TRACE 171 Å channel observations. We show that a recent suggestion regarding a connection between sunspot plumes and 3-min oscillations conflicts with the observations.
Experimental synchronization of circuit oscillations induced by common telegraph noise.
Nagai, Ken; Nakao, Hiroya
2009-03-01
Experimental realization and quantitative investigation of common-noise-induced synchronization of limit-cycle oscillations subject to random telegraph signals are performed using an electronic oscillator circuit. Based on our previous formulation [K. Nagai, Phys. Rev. E 71, 036217 (2005)], dynamics of the circuit is described as random-phase mappings between two limit cycles. Lyapunov exponents characterizing the degree of synchronization are estimated from experimentally determined phase maps and compared with linear damping rates of phase differences measured directly. Noisy on-off intermittency of the phase difference as predicted by the theory is also confirmed experimentally.
Synchronization of moving oscillators in three dimensional space
Majhi, Soumen; Ghosh, Dibakar
2017-05-01
We investigate the macroscopic behavior of a dynamical network consisting of a time-evolving wiring of interactions among a group of random walkers. We assume that each walker (agent) has an oscillator and show that depending upon the nature of interaction, synchronization arises where each of the individual oscillators are allowed to move in such a random walk manner in a finite region of three dimensional space. Here, the vision range of each oscillator decides the number of oscillators with which it interacts. The live interaction between the oscillators is of intermediate type (i.e., not local as well as not global) and may or may not be bidirectional. We analytically derive the density dependent threshold of coupling strength for synchronization using linear stability analysis and numerically verify the obtained analytical results. Additionally, we explore the concept of basin stability, a nonlinear measure based on volumes of basin of attractions, to investigate how stable the synchronous state is under large perturbations. The synchronization phenomenon is analyzed taking limit cycle and chaotic oscillators for wide ranges of parameters like interaction strength k between the walkers, speed of movement v, and vision range r.
Glucose Oscillations Can Activate an Endogenous Oscillator in Pancreatic Islets.
Directory of Open Access Journals (Sweden)
Joseph P McKenna
2016-10-01
Full Text Available Pancreatic islets manage elevations in blood glucose level by secreting insulin into the bloodstream in a pulsatile manner. Pulsatile insulin secretion is governed by islet oscillations such as bursting electrical activity and periodic Ca2+ entry in β-cells. In this report, we demonstrate that although islet oscillations are lost by fixing a glucose stimulus at a high concentration, they may be recovered by subsequently converting the glucose stimulus to a sinusoidal wave. We predict with mathematical modeling that the sinusoidal glucose signal's ability to recover islet oscillations depends on its amplitude and period, and we confirm our predictions by conducting experiments with islets using a microfluidics platform. Our results suggest a mechanism whereby oscillatory blood glucose levels recruit non-oscillating islets to enhance pulsatile insulin output from the pancreas. Our results also provide support for the main hypothesis of the Dual Oscillator Model, that a glycolytic oscillator endogenous to islet β-cells drives pulsatile insulin secretion.
Expected quality factor of a simple tuned oscillator.
Tan, Kia Hock
2011-05-01
A positive feedback system oscillating under self-sustained mode is shown to have an extremely high gain. Modeled as one port, the expected Q is much higher than the loaded Q-factor of the resonator. With just thermal noise present, random phase/frequency deviation is linear. Centered about the oscillator frequency omega/(0), noise frequency on both sides is more amplified with decreasing separation distance. Ultimately, frequency pulling may result in synchronous locking with hysteresis, which occurs because a real oscillator displays a truncated limiting curve. Once locked onto a signal, smaller levels are ignored. A new approach to the design and characterization of a simple tuned oscillator is offered: According to the phenomenon of injection locking, there exists an expected quality factor relating the shape of the truncated limiting curve to an ideal curve. In this paper, synthesis and innovative analytical methods of academic interest are revealed: 1) application of the transducer loss method is revised to establish a new method for oscillator characterization; 2) a transparent method of normalizing a two-port network in the presence of white noise is developed; and 3) in quartz crystal controlled oscillators, characterization of the noise originating from an equivalent noise-resistance determined from parameter of the quartz crystal is proposed. It is shown that the two-port model can also be approximated on a one-port basis. In conclusion, a sample of closed-form estimation of expected Q-factor order of magnitude of piezoelectric resonator oscillators is calculated.
Oscillating flow loss test results in Stirling engine heat exchangers
Koester, G.; Howell, S.; Wood, G.; Miller, E.; Gedeon, D.
1990-01-01
The results are presented for a test program designed to generate a database of oscillating flow loss information that is applicable to Stirling engine heat exchangers. The tests were performed on heater/cooler tubes of various lengths and entrance/exit configurations, on stacked and sintered screen regenerators of various wire diameters and on Brunswick and Metex random fiber regenerators. The test results were performed over a range of oscillating flow parameters consistent with Stirling engine heat exchanger experience. The tests were performed on the Sunpower oscillating flow loss rig which is based on a variable stroke and variable frequency linear drive motor. In general, the results are presented by comparing the measured oscillating flow losses to the calculated flow losses. The calculated losses are based on the cycle integration of steady flow friction factors and entrance/exit loss coefficients.
Modeling microtubule oscillations
DEFF Research Database (Denmark)
Jobs, E.; Wolf, D.E.; Flyvbjerg, H.
1997-01-01
Synchronization of molecular reactions in a macroscopic volume may cause the volume's physical properties to change dynamically and thus reveal much about the reactions. As an example, experimental time series for so-called microtubule oscillations are analyzed in terms of a minimal model...... for this complex polymerization-depolymerization cycle. The model reproduces well the qualitatively different time series that result from different experimental conditions, and illuminates the role and importance of individual processes in the cycle. Simple experiments are suggested that can further test...... and define the model and the polymer's reaction cycle....
From excitability to oscillations
DEFF Research Database (Denmark)
Postnov, D. E.; Neganova, A. Y.; Jacobsen, J. C. B.
2013-01-01
One consequence of cell-to-cell communication is the appearance of synchronized behavior, where many cells cooperate to generate new dynamical patterns. We present a simple functional model of vasomotion based on the concept of a two-mode oscillator with dual interactions: via relatively slow...... diffusive coupling that gives rise to wave dynamics and via fast changes in membrane potential that propagate almost instantly over significant distances. The model reproduces the basic calcium dynamics of the vascular smooth muscle cell: calcium waves which upon increased activity of cGMP-sensitive calcium...
Oscillations in nonlinear systems
Hale, Jack K
2015-01-01
By focusing on ordinary differential equations that contain a small parameter, this concise graduate-level introduction to the theory of nonlinear oscillations provides a unified approach to obtaining periodic solutions to nonautonomous and autonomous differential equations. It also indicates key relationships with other related procedures and probes the consequences of the methods of averaging and integral manifolds.Part I of the text features introductory material, including discussions of matrices, linear systems of differential equations, and stability of solutions of nonlinear systems. Pa
Brain Oscillations, Hypnosis, and Hypnotizability.
Jensen, Mark P; Adachi, Tomonori; Hakimian, Shahin
2015-01-01
This article summarizes the state-of-science knowledge regarding the associations between hypnosis and brain oscillations. Brain oscillations represent the combined electrical activity of neuronal assemblies, usually measured as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations. Hypnosis has been most closely linked to power in the theta band and changes in gamma activity. These oscillations are thought to play a critical role in both the recording and recall of declarative memory and emotional limbic circuits. The authors propose that this role may be the mechanistic link between theta (and perhaps gamma) oscillations and hypnosis, specifically, that the increases in theta oscillations and changes in gamma activity observed with hypnosis may underlie some hypnotic responses. If these hypotheses are supported, they have important implications for both understanding the effects of hypnosis and for enhancing response to hypnotic treatments.
Hyperchaos in coupled Colpitts oscillators
DEFF Research Database (Denmark)
Cenys, Antanas; Tamasevicius, Arunas; Baziliauskas, Antanas
2003-01-01
The paper suggests a simple solution of building a hyperchaotic oscillator. Two chaotic Colpitts oscillators, either identical or non-identical ones are coupled by means of two linear resistors R-k. The hyperchaotic output signal v(t) is a linear combination, specifically the mean of the individu...... oscillators. The spectrum of the Lyapunov exponents (LE) have been calculated versus the coefficient k. For weakly coupled oscillators there are two positive LE indicating hyperchaotic behaviour of the overall system.......The paper suggests a simple solution of building a hyperchaotic oscillator. Two chaotic Colpitts oscillators, either identical or non-identical ones are coupled by means of two linear resistors R-k. The hyperchaotic output signal v(t) is a linear combination, specifically the mean of the individual...
Directory of Open Access Journals (Sweden)
Ki Hwan Kim
Full Text Available Neuronal oscillations produce oscillating magnetic fields. There have been trials to detect neuronal oscillations using MRI, but the detectability in in vivo is still in debate. Major obstacles to detecting neuronal oscillations are (i weak amplitudes, (ii fast oscillations, which are faster than MRI temporal resolution, and (iii random frequencies and on/off intervals. In this study, we proposed a new approach for direct detection of weak and fast oscillating magnetic fields. The approach consists of (i dynamic acquisitions using multiple times to repeats (TRs and (ii an expanded frequency spectral analysis. Gradient echo echo-planar imaging was used to test the feasibility of the proposed approach with a phantom generating oscillating magnetic fields with various frequencies and amplitudes and random on/off intervals. The results showed that the proposed approach could precisely detect the weak and fast oscillating magnetic fields with random frequencies and on/off intervals. Complex and phase spectra showed reliable signals, while no meaningful signals were observed in magnitude spectra. A two-TR approach provided an absolute frequency spectrum above Nyquist sampling frequency pixel by pixel with no a priori target frequency information. The proposed dynamic multiple-TR imaging and Fourier analysis are promising for direct detection of neuronal oscillations and potentially applicable to any pulse sequences.
Linearization of conservative nonlinear oscillators
Energy Technology Data Exchange (ETDEWEB)
Belendez, A; Alvarez, M L [Departamento de Fisica, IngenierIa de Sistemas y TeorIa de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E; Pascual, I [Departamento de Optica, FarmacologIa y AnatomIa, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es
2009-03-11
A linearization method of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force which allows us to obtain a frequency-amplitude relation which is valid not only for small but also for large amplitudes and, sometimes, for the complete range of oscillation amplitudes. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of the technique.
A Matterwave Transistor Oscillator
Caliga, Seth C; Zozulya, Alex A; Anderson, Dana Z
2012-01-01
A triple-well atomtronic transistor combined with forced RF evaporation is used to realize a driven matterwave oscillator circuit. The transistor is implemented using a metalized compound glass and silicon substrate. On-chip and external currents produce a cigar-shaped magnetic trap, which is divided into transistor source, gate, and drain regions by a pair of blue-detuned optical barriers projected onto the magnetic trap through a chip window. A resonant laser beam illuminating the drain portion of the atomtronic transistor couples atoms emitted by the gate to the vacuum. The circuit operates by loading the source with cold atoms and utilizing forced evaporation as a power supply that produces a positive chemical potential in the source, which subsequently drives oscillation. High-resolution in-trap absorption imagery reveals gate atoms that have tunneled from the source and establishes that the circuit emits a nominally mono-energetic matterwave with a frequency of 23.5(1.0) kHz by tunneling from the gate, ...
Heat exchanger with oscillating flow
Scotti, Stephen J. (Inventor); Blosser, Max L. (Inventor); Camarda, Charles J. (Inventor)
1993-01-01
Various heat exchange apparatuses are described in which an oscillating flow of primary coolant is used to dissipate an incident heat flux. The oscillating flow may be imparted by a reciprocating piston, a double action twin reciprocating piston, fluidic oscillators or electromagnetic pumps. The oscillating fluid flows through at least one conduit in either an open loop or a closed loop. A secondary flow of coolant may be used to flow over the outer walls of at least one conduit to remove heat transferred from the primary coolant to the walls of the conduit.
The Duffing oscillator with damping
DEFF Research Database (Denmark)
Johannessen, Kim
2015-01-01
An analytical solution to the differential equation describing the Duffing oscillator with damping is presented. The damping term of the differential equation and the initial conditions satisfy an algebraic equation, and thus the solution is specific for this type of damping. The nonlinear term....... It is established that the period of oscillation is shorter compared to that of a linearized model but increasing with time and asymptotically approaching the period of oscillation of the linear damped model. An explicit expression for the period of oscillation has been derived, and it is found to be very accurate....
Unstable oscillators based hyperchaotic circuit
DEFF Research Database (Denmark)
Murali, K.; Tamasevicius, A.; G. Mykolaitis, A.
1999-01-01
A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations in the circ......A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations...
Power Spectrum Density of Stochastic Oscillating Accretion Disk
Indian Academy of Sciences (India)
Keywords. Accretion; accretion disks; black hole physics; instabilities. ... In the model, we assume that there is a relativistic oscillation of thin accretion disks and it interacts with an external thermal bath through a friction force and a random force. ... Department of Physics, Yunnan Normal University, Kunming 650500, China.
Coronal Waves and Oscillations
Directory of Open Access Journals (Sweden)
Nakariakov Valery M.
2005-07-01
Full Text Available Wave and oscillatory activity of the solar corona is confidently observed with modern imaging and spectral instruments in the visible light, EUV, X-ray and radio bands, and interpreted in terms of magnetohydrodynamic (MHD wave theory. The review reflects the current trends in the observational study of coronal waves and oscillations (standing kink, sausage and longitudinal modes, propagating slow waves and fast wave trains, the search for torsional waves, theoretical modelling of interaction of MHD waves with plasma structures, and implementation of the theoretical results for the mode identification. Also the use of MHD waves for remote diagnostics of coronal plasma - MHD coronal seismology - is discussed and the applicability of this method for the estimation of coronal magnetic field, transport coefficients, fine structuring and heating function is demonstrated.
Hyperchaotic system with unstable oscillators
DEFF Research Database (Denmark)
Murali, K.; Tamasevicius, A.; Mykolaitis, G.
2000-01-01
A simple electronic system exhibiting hyperchaotic behaviour is described. The system includes two nonlinearly coupled 2nd order unstable oscillators, each composed of an LC resonance loop and an amplifier. The system is investigated by means of numerical integration of appropriate differential...... equations, PSPICE simulations and hardware experiments. The Lyapunov exponents are presented to confirm hyperchaotic mode of the oscillations....
The Wien Bridge Oscillator Family
DEFF Research Database (Denmark)
Lindberg, Erik
2006-01-01
A tutorial in which the Wien bridge family of oscillators is defined and investigated. Oscillators which do not fit into the Barkhausen criterion topology may be designed. A design procedure based on initial complex pole quality factor is reported. The dynamic transfer characteristic...
Energy Conservative Limit Cycle Oscillations
Stramigioli, Stefano; van Dijk, Michel
This paper shows how globally attractive limit cycle oscillations can be induced in a system with a nonlinear feedback element. Based on the same principle as the Van der Pol oscillator, the feedback behaves as a negative damping for low velocities but as an ordinary damper for high velocities. This
Mechanical Parametric Oscillations and Waves
Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.
2013-01-01
Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…
Augmenting cognition by neuronal oscillations
Horschig, J.M.; Zumer, J.; Bahramisharif, A.
2014-01-01
Cortical oscillations have been shown to represent fundamental functions of a working brain, e.g., communication, stimulus binding, error monitoring, and inhibition, and are directly linked to behavior. Recent studies intervening with these oscillations have demonstrated effective modulation of both
Dudinets, I. V.; Man’ko, V. I.; Marmo, G.; Zaccaria, F.
2017-11-01
Symplectic tomographies of classical and quantum states are shortly reviewed. The concept of nonlinear f-oscillators and their properties are recalled. The tomographic probability representations of oscillator coherent states and the problem of entanglement are then discussed. The entanglement of even and odd f-coherent states is evaluated by the linear entropy.
Quasi Periodic Oscillations in Blazars
Indian Academy of Sciences (India)
2016-01-27
Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy; Volume 35; Issue 3. Quasi Periodic Oscillations in Blazars ... Here we report our recent discoveries of Quasi-Periodic Oscillations (QPOs) in blazars time series data in X-ray and optical electromagnetic bands. Any such detection can give important ...
Prospects for Neutrino Oscillation Physics
Directory of Open Access Journals (Sweden)
Silvia Pascoli
2013-01-01
Full Text Available Recently the last unknown lepton mixing angle θ 13 has been determined to be relatively large, not too far from its previous upper bound. This opens exciting possibilities for upcoming neutrino oscillation experiments towards addressing fundamental questions, among them the type of the neutrino mass hierarchy and the search for CP violation in the lepton sector. In this paper we review the phenomenology of neutrino oscillations, focusing on subleading effects, which will be the key towards these goals. Starting from a discussion of the present determination of three-flavour oscillation parameters, we give an outlook on the potential of near-term oscillation physics as well as on the long-term program towards possible future precision oscillation facilities. We discuss accelerator-driven long-baseline experiments as well as nonaccelerator possibilities from atmospheric and reactor neutrinos.
Oscillating nonlinear acoustic shock waves
DEFF Research Database (Denmark)
Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth
2016-01-01
We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... that at resonance a stationary state arise consisting of multiple oscillating shock waves. Off resonance driving leads to a nearly linear oscillating ground state but superimposed by bursts of a fast oscillating shock wave. Based on a travelling wave ansatz for the fluid velocity potential with an added 2'nd order...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....
Bimodal oscillations in nephron autoregulation
DEFF Research Database (Denmark)
Sosnovtseva, Olga; Pavlov, A N; Mosekilde, E
2002-01-01
The individual functional unit of the kidney (the nephron) displays oscillations in its pressure and flow regulation at two different time scales: fast oscillations associated with a myogenic dynamics of the afferent arteriole, and slower oscillations arising from a delay in the tubuloglomerular...... feedback. We investigate the intra- and internephron entrainment of the two time scales. In addition to full synchronization, both wavelet analyses of experimental data and numerical simulations reveal a partial entrainment in which neighboring nephrons attain a state of chaotic synchronization...
Collective oscillations in a plasma
Akhiezer, A I; Polovin, R V; ter Haar, D
2013-01-01
International Series of Monographs in Natural Philosophy: Collective Oscillations in a Plasma, Volume 7 presents specific topics within the general field of radio waves propagation. This book contains five chapters that address the theory of linear oscillations in a plasma, the spectra of the eigen oscillations, and the mechanism of high-frequency heating. The opening chapters deal with the self-consistent fields; development of initial perturbation; dispersion permittivity tensor of a plasma in a magnetic field; effect of thermal motion of particles on low-frequency resonances; excitation of
Model of stochastic self-oscillation in Gunn diode oscillators
Energy Technology Data Exchange (ETDEWEB)
Bocharov, E.P.; Korostelev, G.N.; Khripunov, M.V.
1987-07-01
The applicability of the two-mode nonlinear model of decay stochasticity for explanation of the transition from monochromatic self-oscillation to developed stochasticity in the Gunn diode oscillator is demonstrated. Numerical realizations of the basic regimes corresponding to various cases of consideration of the weak nonlinearity of the falling portion of the current-voltage characteristic are presented. A comparative analysis of calculation results of time realizations and experimentally observed oscillograms of stochastic regimes is performed.
Oscillations in Mathematical Biology
1983-01-01
The papers in this volume are based on talks given at a one day conference held on the campus of Adelphi University in April 1982. The conference was organized with the title "Oscillations in Mathematical Biology;" however the speakers were allowed considerable latitutde in their choice of topics. In the event, the talks all concerned the dynamics of non-linear systems arising in biology so that the conference achieved a good measure of cohesion. Some of the speakers cho~e not to submit a manuscript for these proceedings, feeling that their material was too conjectural to be committed to print. Also the paper of Rinzel and Troy is a distillation of the two separate talks that the authors gave. Otherwise the material reproduces the conference proceedings. The conference was made possible by the generous support of the Office of the Dean of the College of Arts and Sciences at Adelphi. The bulk of the organization of the conference was carried out by Dr. Ronald Grisell whose energy was in large measure responsib...
Strong nonlinear oscillators analytical solutions
Cveticanin, Livija
2017-01-01
This book outlines an analytical solution procedure of the pure nonlinear oscillator system, offering a solution for free and forced vibrations of the one-degree-of-freedom strong nonlinear system with constant and time variable parameter. Includes exercises.
Long period oscillations in sunspots
Chorley, N.; Hnat, B.; Nakariakov, V. M.; Inglis, A. R.; Bakunina, I. A.
2010-04-01
Long period oscillations of the gyroresonant emission from sunspot atmospheres are studied. Time series data generated from the sequences of images obtained by the Nobeyama Radioheliograph operating at a frequency of 17 GHz for three sunspots have been analysed and are found to contain significant periods in the range of several tens of minutes. Wavelet analysis shows that these periods are persistent throughout the observation periods. The presence of the oscillations is confirmed by several methods (periodogram, wavelets, Fisher randomisation and empirical mode decomposition). Spatial analysis using the techniques of period, power, correlation and time lag mapping reveals regions of enhanced oscillatory power in the umbral regions. Also seen are two regions of coherent oscillation of about 25 pixels in size, that oscillate in anti-phase with each other. Possible interpretation of the observed periodicities is discussed, in terms of the shallow sunspot model and the leakage of the solar g-modes.
Building a Synthetic Transcriptional Oscillator.
Schwarz-Schilling, Matthaeus; Kim, Jongmin; Cuba, Christian; Weitz, Maximilian; Franco, Elisa; Simmel, Friedrich C
2016-01-01
Reaction circuits mimicking genetic oscillators can be realized with synthetic, switchable DNA genes (so-called genelets), and two enzymes only, an RNA polymerase and a ribonuclease. The oscillatory behavior of the genelets is driven by the periodic production and degradation of RNA effector molecules. Here, we describe the preparation, assembly, and testing of a synthetic, transcriptional two-node negative-feedback oscillator, whose dynamics can be followed in real-time by fluorescence read-out.
An Oscillating Magnet Watt Balance
Ahmedov, H.
2015-01-01
We establish the principles for a new generation of simplified and accurate watt balances in which an oscillating magnet generates Faraday's voltage in a stationary coil. A force measuring system and a mechanism providing vertical movements of the magnet are completely independent in an oscillating magnet watt balance. This remarkable feature allows to establish the link between the Planck constant and a macroscopic mass by a one single experiment. Weak dependence on variations of environment...
Entrainment of heterogeneous glycolytic oscillations in single cells
Gustavsson, A -K; Mehlig, B; Goksör, M
2015-01-01
Cell signaling, gene expression, and metabolism are affected by cell-cell heterogeneity and random changes in the environment. The effects of such fluctuations on cell signaling and gene expression have recently been studied intensively using single-cell experiments. In metabolism heterogeneity may be particularly important because it may affect synchronisation of metabolic oscillations, an important example of cell-cell communication. This synchronisation is notoriously difficult to describe theoretically as the example of glycolytic oscillations shows: neither is the mechanism of glycolytic synchronisation understood nor the role of cell-cell heterogeneity. To pin down the mechanism and to assess its robustness and universality we have experimentally investigated the entrainment of glycolytic oscillations in individual yeast cells by periodic external perturbations. We find that oscillatory cells synchronise through phase shifts and that the mechanism is insensitive to cell heterogeneity (robustness) and si...
Modeling nonlinearities in MEMS oscillators.
Agrawal, Deepak K; Woodhouse, Jim; Seshia, Ashwin A
2013-08-01
We present a mathematical model of a microelectromechanical system (MEMS) oscillator that integrates the nonlinearities of the MEMS resonator and the oscillator circuitry in a single numerical modeling environment. This is achieved by transforming the conventional nonlinear mechanical model into the electrical domain while simultaneously considering the prominent nonlinearities of the resonator. The proposed nonlinear electrical model is validated by comparing the simulated amplitude-frequency response with measurements on an open-loop electrically addressed flexural silicon MEMS resonator driven to large motional amplitudes. Next, the essential nonlinearities in the oscillator circuit are investigated and a mathematical model of a MEMS oscillator is proposed that integrates the nonlinearities of the resonator. The concept is illustrated for MEMS transimpedance-amplifier- based square-wave and sine-wave oscillators. Closed-form expressions of steady-state output power and output frequency are derived for both oscillator models and compared with experimental and simulation results, with a good match in the predicted trends in all three cases.
On the nonlinear modeling of ring oscillators
Elwakil, Ahmed S.
2009-06-01
We develop higher-order nonlinear models of three-stage and five-stage ring oscillators based on a novel inverter model. The oscillation condition and oscillation frequency are derived and compared to classical linear model analysis. Two important special cases for five-stage ring oscillators are also studied. Numerical simulations are shown. © 2009 World Scientific Publishing Company.
A theory of generalized Bloch oscillations
DEFF Research Database (Denmark)
Duggen, Lars; Lew Yan Voon, L. C.; Lassen, Benny
2016-01-01
Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact cal...... oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics.......Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact...... calculation is given to confirm this phenomenon. Our results allow for a greater freedom of design for experimentally observing Bloch oscillations. For strongly coupled oscillator systems displaying Bloch oscillations, it is further demonstrated that reordering of oscillators leads to destruction of Bloch...
On the mechanism of oscillations in neutrophils
DEFF Research Database (Denmark)
Brasen, Jens Christian; Barington, Torben; Olsen, Lars Folke
2010-01-01
of the external glucose concentration and the oscillations in H(2)O(2) production are 180 degrees out of phase with the oscillations in NAD(P)H. Cytochalasin B blocked the oscillations in shape and size whereas it increased the period of the oscillations in H(2)O(2) production. 1- and 2-butanol also blocked...... the oscillations in shape and size, but only 1-butanol inhibited the oscillations in H(2)O(2) production. We conjecture that the oscillations are likely to be due to feedback regulations in the signal transduction cascade involving phosphoinositide 3-kinases (PI3K). We have tested this using a simple mathematical......We have investigated the regulation of the oscillatory generation of H(2)O(2) and oscillations in shape and size in neutrophils in suspension. The oscillations are independent of cell density and hence do not represent a collective phenomena. Furthermore, the oscillations are independent...
Random vibrations theory and practice
Wirsching, Paul H; Ortiz, Keith
1995-01-01
Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...
Parzen, Benjamin
1992-01-01
The theory of oscillator analysis in the immittance domain should be read in conjunction with the additional theory presented here. The combined theory enables the computer simulation of the steady state oscillator. The simulation makes the calculation of the oscillator total steady state performance practical, including noise at all oscillator locations. Some specific precision oscillators are analyzed.
Role of Frontal Alpha Oscillations in Creativity
Lustenberger, Caroline; Boyle, Michael R.; Foulser, A. Alban; Mellin, Juliann M.; Fröhlich, Flavio
2015-01-01
Creativity, the ability to produce innovative ideas, is a key higher-order cognitive function that is poorly understood. At the level of macroscopic cortical network dynamics, recent EEG data suggests that cortical oscillations in the alpha frequency band (8 – 12 Hz) are correlated with creative thinking. However, whether alpha oscillations play a fundamental role in creativity has remained unknown. Here we show that creativity is increased by enhancing alpha power using 10 Hz transcranial alternating current stimulation (10Hz-tACS) of the frontal cortex. In a study of 20 healthy participants with a randomized, balanced cross-over design, we found a significant improvement of 7.4% in the Creativity Index measured by the Torrance Test of Creative Thinking, a comprehensive and most frequently used assay of creative potential and strengths. In a second similar study with 20 subjects, 40Hz-tACS was used in instead of 10Hz-tACS to rule out a general “electrical stimulation” effect. No significant change in the Creativity Index was found for such frontal gamma stimulation. Our results suggest that alpha activity in frontal brain areas is selectively involved in creativity; this enhancement represents the first demonstration of specific neuronal dynamics that drive creativity and can be modulated by non-invasive brain stimulation. Our findings agree with the model that alpha recruitment increases with internal processing demands and is involved in inhibitory top-down control, which is an important requirement for creative ideation. PMID:25913062
Burst Oscillation Studies with NICER
Mahmoodifar, Simin; Strohmayer, Tod E.
2017-08-01
Type I X-ray bursts are thermonuclear flashes observed from the surfaces of accreting neutron stars in Low Mass X-ray Binaries. Oscillations have been observed during the rise and/or decay of some of these X-ray bursts. Those seen during the rise can be well explained by a spreading hot spot model, but large amplitude oscillations in the decay phase remain mysterious because of the absence of a clear-cut source of asymmetry. Here we present the results of our computations of the light curves and amplitudes of oscillations in X-ray burst models that realistically account for both flame spreading and subsequent cooling. For the cooling phase of the burst we use two simple phenomenological models. The first considers asymmetric cooling that can achieve high amplitudes in the tail. The second considers a sustained temperature pattern on the stellar surface that is produced by r-modes propagating in the surface fluid ocean of the star. We will present some simulated burst light curves/spectra using these models and NICER response files, and will show the capabilities of NICER to detect and study burst oscillations. NICER will enable us to study burst oscillations in the energy band below ~3 keV, where there has been no previous measurements of these phenomena.
ALG-2 oscillates in subcellular localization, unitemporally with calcium oscillations
DEFF Research Database (Denmark)
la Cour, Jonas Marstrand; Mollerup, Jens; Berchtold, Martin Werner
2007-01-01
discovered that the subcellular distribution of a tagged version of ALG-2 could be directed by physiological external stimuli (including ATP, EGF, prostaglandin, histamine), which provoke intracellular Ca2+ oscillations. Cellular stimulation led to a redistribution of ALG-2 from the cytosol to a punctate...... localization in an oscillatory fashion unitemporally with Ca2+ oscillations, whereas a Ca2+-binding deficient mutant of ALG-2 did not redistribute. Using tagged ALG-2 as bait we identified its novel target protein Sec31A and based on the partial colocalization of endogenous ALG-2 and Sec31A we propose that ALG...
Modal analysis of rip current cell oscillations
Geiman, J.; Kirby, J. T.; Reniers, A. J.; Macmahan, J. H.
2010-12-01
A numerical simulation of a random directional wave-driven flow over an alongshore periodic rip-channeled beach using the wave-resolving model Funwave is used to investigate coherent, very-low frequency (VLF) motions inside of the surf zone generated by wave breaking. By reducing the degrees of freedom in the resulting complex vorticity field via two different methods: principle orthogonal decomposition (POD) and dynamic mode decomposition (DMD), the dominant spatial modes describing the slow (<0.002 Hz) rip circulation cell oscillation are extracted and compared with the spatial and temporal distribution of wave breaking dissipation. The reduced flow field, consisting of only a few of the POD or DMD modes is shown to describe most of the Lagrangian stirring along the surf-zone and offshore fluid interface and between neighboring rip current cells.
Oscillation phenomenon of transition temperatures of coupled magnetic planes
Directory of Open Access Journals (Sweden)
H. Moradi
2004-06-01
Full Text Available Oscillatory behavior of transition temperature in supper lattice, Ni/Au/Ni, has been observed as a function of spacer layer, Au. The observed oscillation period is almost the half period of interlayer exchange coupling. The high temperature susceptibility of a two - dimensional lattice is evaluated within the Bethe-Peierls-Wiess approximation in the presence of a random field with square distribution. This susceptibility is used to evaluate the transition temperature of coupled planes as a function of spacer thickness. The calculated transition temperature of coupled planes oscillates as half period of interlayer exchange coupling and falls below the results of the uncoupled films at some values of the average spacer thickness that were experimentally observed. Additionally, the transition temperature depends on the distribution function of random field at the small thickness of spacer.
Restoration of oscillation in network of oscillators in presence of direct and indirect interactions
Energy Technology Data Exchange (ETDEWEB)
Majhi, Soumen; Bera, Bidesh K. [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India); Bhowmick, Sourav K. [Department of Electronics, Asutosh College, Kolkata-700026 (India); Ghosh, Dibakar, E-mail: diba.ghosh@gmail.com [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India)
2016-10-23
The suppression of oscillations in coupled systems may lead to several unwanted situations, which requires a suitable treatment to overcome the suppression. In this paper, we show that the environmental coupling in the presence of direct interaction, which can suppress oscillation even in a network of identical oscillators, can be modified by introducing a feedback factor in the coupling scheme in order to restore the oscillation. We inspect how the introduction of the feedback factor helps to resurrect oscillation from various kinds of death states. We numerically verify the resurrection of oscillations for two paradigmatic limit cycle systems, namely Landau–Stuart and Van der Pol oscillators and also in generic chaotic Lorenz oscillator. We also study the effect of parameter mismatch in the process of restoring oscillation for coupled oscillators. - Highlights: • Amplitude death is observed using direct and indirect coupling. • Revival of oscillation using feedback parameter is discussed. • Restoration of oscillation is observed in limit cycle and chaotic systems.
Investigation of Transverse Oscillation Method
DEFF Research Database (Denmark)
Udesen, Jesper; Jensen, Jørgen Arendt
2006-01-01
oscillation and an axial oscillation in the pulse echo field. The theory behind the creation of the double oscillation pulse echo field is explained as well as the theory behind the estimation of the vector velocity. A parameter study of the method is performed, using the ultrasound simulation program Field...... II. A virtual linear array transducer with center frequency 7 MHz and 128 active elements is created, and a virtual blood vessel of radius 6.4 mm is simulated. The performance of the TO method is found around an initial point in the parameter space. The parameters varied are: flow angle, transmit...... focus depth, receive apodization, pulse length, transverse wave length, number of emissions, signal to noise ratio, and type of echo canceling filter used. Using the experimental scanner RASMUS, the performance of the TO method is evaluated. An experimental flowrig is used to create laminar parabolic...
Prediction of pilot induced oscillations
Directory of Open Access Journals (Sweden)
Valentin PANĂ
2011-03-01
Full Text Available An important problem in the design of flight-control systems for aircraft under pilotedcontrol is the determination of handling qualities and pilot-induced oscillations (PIO tendencieswhen significant nonlinearities exist in the vehicle description. The paper presents a method to detectpossible pilot-induced oscillations of Category II (with rate and position limiting, a phenomenonusually due to a misadaptation between the pilot and the aircraft response during some tasks in whichtight closed loop control of the aircraft is required from the pilot. For the analysis of Pilot in the LoopOscillations an approach, based on robust stability analysis of a system subject to uncertainparameters, is proposed. In this analysis the nonlinear elements are substituted by linear uncertainparameters. This approach assumes that PIO are characterized by a limit cycle behavior.
Hidden symmetries of deformed oscillators
Directory of Open Access Journals (Sweden)
Sergey Krivonos
2017-11-01
Full Text Available We associate with each simple Lie algebra a system of second-order differential equations invariant under a non-compact real form of the corresponding Lie group. In the limit of a contraction to a Schrödinger algebra, these equations reduce to a system of ordinary harmonic oscillators. We provide two clarifying examples of such deformed oscillators: one system invariant under SO(2,3 transformations, and another system featuring G2(2 symmetry. The construction of invariant actions requires adding semi-dynamical degrees of freedom; we illustrate the algorithm with the two examples mentioned.
Oscillating-Coolant Heat Exchanger
Scotti, Stephen J.; Blosser, Max L.; Camarda, Charles J.
1992-01-01
Devices useful in situations in which heat pipes inadequate. Conceptual oscillating-coolant heat exchanger (OCHEX) transports heat from its hotter portions to cooler portions. Heat transported by oscillation of single-phase fluid, called primary coolant, in coolant passages. No time-averaged flow in tubes, so either heat removed from end reservoirs on every cycle or heat removed indirectly by cooling sides of channels with another coolant. Devices include leading-edge cooling devices in hypersonic aircraft and "frost-free" heat exchangers. Also used in any situation in which heat pipe used and in other situations in which heat pipes not usable.
Ladder operators for isospectral oscillators
Seshadri, S.; Balakrishnan, V.; Lakshmibala, S.
1998-02-01
We present, for the isospectral family of oscillator Hamiltonians, a systematic procedure for constructing raising and lowering operators satisfying any prescribed "distorted" Heisenberg algebra (including the q-generalization). This is done by means of an operator transformation implemented by a shift operator. The latter is obtained by solving an appropriate partial isometry condition in the Hilbert space. Formal representations of the nonlocal operators concerned are given in terms of pseudo-differential operators. Using the new annihilation operators, new classes of coherent states are constructed for isospectral oscillator Hamiltonians. The corresponding Fock-Bargmann representations are also considered, with specific reference to the order of the entire function family in each case.
Energy Technology Data Exchange (ETDEWEB)
Ates, Sule, E-mail: suleates@selcuk.edu.tr; Oezarslan, Selma; Celik, Gueltekin; Taser, Mehmet
2012-07-15
The electric dipole oscillator strengths for lines between some singlet and triplet levels have been calculated using the weakest bound electron potential model theory and the quantum defect orbital theory for Be I. In the calculations both multiplet and fine structure transitions are studied. We employed both the numerical Coulomb approximation method and numerical non-relativistic Hartree-Fock wavefunctions for expectation values of radii. The necessary energy values have been taken from experimental energy data in the literature. The calculated oscillator strengths have been compared with available theoretical results. A good agreement with the results in the literature has been obtained.
Energy Technology Data Exchange (ETDEWEB)
Maccari, A. [Istituto Tecnico `G. Cardano`, Monterotondo, Rome (Italy)
1996-08-01
The most important characteristics of the non-local oscillator, an oscillator subjected to an additional non-local force, are extensively studied by means of a new asymptotic perturbation method that is able to furnish an approximate solution of weakly non-linear differential equations. The resulting motion is doubly periodic, because a second little frequency appears, in addition to the fundamental harmonic frequency. Comparison with the numerical solution obtained by the Runge-Kitta method confirms the validity of the asymptotic perturbation method and its importance for the study of non-linear dynamical systems.
TOWARDS THRESHOLD FREQUENCY IN CHAOTIC COLPITTS OSCILLATOR
DEFF Research Database (Denmark)
Lindberg, Erik; Tamasevicius, Arunas; Mykolaitis, Gytis
2007-01-01
A novel version of chaotic Colpitts oscillator is described. Instead of a linear loss resistor, it includes an extra inductor and diode in the collector circuit of the transistor. The modified circuit in comparison with the common Colpitts oscillator may generate chaotic oscillations at the funda......A novel version of chaotic Colpitts oscillator is described. Instead of a linear loss resistor, it includes an extra inductor and diode in the collector circuit of the transistor. The modified circuit in comparison with the common Colpitts oscillator may generate chaotic oscillations...
Comparison of phase noise simulation techniques on a BJT LC oscillator.
Forbes, Leonard; Zhang, Chengwei; Zhang, Binglei; Chandra, Yudi
2003-06-01
The phase noise resulting from white and flicker noise in a bipolar junction transistor (BJT) LC oscillator is investigated. Large signal transient time domain SPICE simulations of phase noise resulting from the random-phase flicker and white noise in a 2 GHz BJT LC oscillator have been performed and demonstrated. The simulation results of this new technique are compared with Eldo RF and Spectre RF based on linear circuit concepts and experimental result reported in the literature.
Willocq, S
2002-01-01
We review new studies of the time dependence of B0s - B0s-bar mixing by the ALEPH, DELPHI and SLD Collaborations, with an emphasis on the different analysis methods used. Combining all available results yields a preliminary lower limit on the oscillation frequency of dms > 14.4 ps-1 at the 95% C.L.
Oscillating solitons in nonlinear optics
Indian Academy of Sciences (India)
Abstract. Oscillating solitons are obtained in nonlinear optics. Analytical study of the variable- coefficient nonlinear Schrödinger equation, which is used to describe the soliton propagation in those systems, is carried out using the Hirota's bilinear method. The bilinear forms and analytic soliton solutions are derived, and the ...
Chemical Oscillations-Mathematical Modelling
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 7. Chemical Oscillations - Mathematical Modelling ... Protein Science and Engineering Unit Institute of Microbial Technology Sector 39A Chandigarh 160 036; Department of Chemistry and Centre for Advanced Studies in Chemistry Punjab ...
Cubication of Conservative Nonlinear Oscillators
Belendez, Augusto; Alvarez, Mariela L.; Fernandez, Elena; Pascual, Immaculada
2009-01-01
A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear…
Linearization of Conservative Nonlinear Oscillators
Belendez, A.; Alvarez, M. L.; Fernandez, E.; Pascual, I.
2009-01-01
A linearization method of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force which allows us to obtain a frequency-amplitude relation which is valid not only for small but also for large amplitudes and, sometimes, for…
Sum rules for neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Kobzarev, I.Yu.; Nartem' yanov, B.V.; Okun, L.B.; Shchepkin, M.G. (Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Teoreticheskoj i Ehksperimental' noj Fiziki)
1982-05-01
Sum rules for neutrino oscillations have been obtained. The effects due to the neutrino masses are taken into account, msub(..nu..) being not assumed to be a small parameter. Study of the ''binary'' lsub(i)sup(-) ..-->.. ..nu.. ..-->.. lsub(k)sup(+-) process permits to accurately take into account neutrino masses and to obtain expressions for the cross sections oscillating as functions of distance L between the points of neutrino production and absorption. In the case of Dirac or left Majoran masses obtained is the sum rule according to which the cross section sigma(lsub(i)sup(-) ..-->.. lsub(k)sup(-)) summarized with the weight 1/vsub(k) by aromas of final lepton remains constant (exactly, decrease as 1/L/sup 2/) and it does not oscillate. In the case of left Majoran masses there is admixture of antineutrino due to which the lsub(i)sup(-) ..-->.. lsub(k)sup(+) process is possible. In this case both components (neutrino with antineutrino admixture) oscillates independently and there exists analogous sum rule for the sigma(lsub(i)sup(-) ..-->.. lsub(k)sup(+)) cross section.
Discovery of atmospheric neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Kajita, Takaaki [Tokyo Univ., Inst. for Cosmic Ray Research, Kashiwa, Chiba (Japan)
2003-05-01
Cosmic ray particles entering the atmosphere interact with the air nuclei produce neutrinos. These neutrinos are called atmospheric neutrinos. The atmospheric neutrino anomaly observed in Kamiokande is now understood as due to neutrino oscillations by high statistics measurements of the atmospheric neutrinos in Super-Kamiokande. The studies of the atmospheric neutrinos have matured into detailed studies of neutrino masses and mixings. (author)
Sustained oscillations in living cells
Danø, Sune; Sørensen, Preben Graae; Hynne, Finn
1999-11-01
Glycolytic oscillations in yeast have been studied for many years simply by adding a glucose pulse to a suspension of cells and measuring the resulting transient oscillations of NADH. Here we show, using a suspension of yeast cells, that living cells can be kept in a well defined oscillating state indefinitely when starved cells, glucose and cyanide are pumped into a cuvette with outflow of surplus liquid. Our results show that the transitions between stationary and oscillatory behaviour are uniquely described mathematically by the Hopf bifurcation. This result characterizes the dynamical properties close to the transition point. Our perturbation experiments show that the cells remain strongly coupled very close to the transition. Therefore, the transition takes place in each of the cells and is not a desynchronization phenomenon. With these two observations, a study of the kinetic details of glycolysis, as it actually takes place in a living cell, is possible using experiments designed in the framework of nonlinear dynamics. Acetaldehyde is known to synchronize the oscillations. Our results show that glucose is another messenger substance, as long as the glucose transporter is not saturated.
Sound oscillation of dropwise cluster
Energy Technology Data Exchange (ETDEWEB)
Shavlov, A.V., E-mail: shavlov@ikz.ru [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation); Dzhumandzhi, V.A.; Romanyuk, S.N. [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation)
2012-06-04
There was registered sound oscillation of a dropwise cluster formed over the warmed-up water surface. We have calculated the electrical charge of drops on the basis of experimental data on ion-sound oscillation. It was demonstrated that the charge is proportional to surface area of the drops and does not depend on intensity of their evaporation (condensation) in the range of 60–100 °C. The charge of drops reaches 10{sup 2}–10{sup 3} units of elementary charge and coincides on magnitude order with the literary value of a charge calculated by another method. -- Highlights: ► The present investigation registered short-wave sound oscillations of water drops in a dropwise cluster in the range of 60–100 °C. ► We have found autocorrelation functions and Fourier transforms of time series of interdroplet distance; defined oscillation frequencies. ► Calculated electrical charge of drops and specified that the charge is proportional to the drop surface area.
Analytic Neutrino Oscillation Probabilities in Matter: Revisited
Energy Technology Data Exchange (ETDEWEB)
Parke, Stephen J. [Fermilab; Denton, Peter B. [Copenhagen U.; Minakata, Hisakazu [Madrid, IFT
2018-01-02
We summarize our recent paper on neutrino oscillation probabilities in matter, explaining the importance, relevance and need for simple, highly accurate approximations to the neutrino oscillation probabilities in matter.
Quantum oscillations in the chiral magnetic conductivity
Kaushik, Sahal; Kharzeev, Dmitri E.
2017-06-01
In strong magnetic field, the longitudinal magnetoconductivity in three-dimensional chiral materials is shown to exhibit a new type of quantum oscillations arising from the chiral magnetic effect (CME). These quantum CME oscillations are predicted to dominate over the Shubnikov-de Haas (SdH) ones in chiral materials with an approximately conserved chirality of quasiparticles at strong magnetic fields. The phase of quantum CME oscillations differs from the phase of the conventional SdH oscillations by π /2 .
Nonlinear analysis of ring oscillator circuits
Ge, Xiaoqing
2010-06-01
Using nonlinear systems techniques, we analyze the stability properties and synchronization conditions for ring oscillator circuits, which are essential building blocks in digital systems. By making use of its cyclic structure, we investigate local and global stability properties of an n-stage ring oscillator. We present a sufficient condition for global asymptotic stability of the origin and obtain necessity if the ring oscillator consists of identical inverter elements. We then give a synchronization condition for identical interconnected ring oscillators.
Coherence in Complex Networks of Oscillators
Lind, Pedro G.; Gallas, Jason A. C.; Herrmann, Hans J.
We study fully synchronized (coherent) states in complex networks of chaotic oscillators, reviewing the analytical approach of determining the stability conditions for synchronizability and comparing them with numerical criteria. As an example, we present detailed results for networks of chaotic logistic maps having three different scale-free topologies: random scale-free topology, deterministic pseudo-fractal scale-free network and Apollonian network. For random scale-free topology we find that the lower boundary of the synchronizability region scales approximately as k-μ, where k is the outgoing connectivity and μ depends on the local nonlinearity. For deterministic scale-free networks coherence is observed only when the coupling is heterogeneous, namely when it is proportional to some power of the neighbour connectivity. In all cases, stability conditions are determined from the eigenvalue spectrum of the Laplacian matrix and agree well with numerical results based on histograms of coherent states in parameter space. Additionally, we show that almost everywhere in the synchronizability region the basin of attraction of the coherent states fills the entire phase space, and that the transition to coherence is of first-order.
Assessing the quality of stochastic oscillations
Indian Academy of Sciences (India)
Population dynamics; stochastic oscillations. ... We propose a quantification of the oscillatory appearance of the fluctuating populations, and show that good stochastic oscillations are present if a parameter of the macroscopic model is small, and that no microscopic model will show oscillations if that parameter is large.
Internal dynamics of long Josephson junction oscillators
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Lomdahl, P. S.; Scott, Alwyn C.
1981-01-01
Numerical computations on a sine-Gordon model of the Josephson junction fluxon oscillator are compared with experimental measurements. Good agreement is found for the voltage current characteristic, oscillator power output, and range of current bias over which oscillation is observed. Our numerical...
Comparison of Methods for Oscillation Detection
DEFF Research Database (Denmark)
Odgaard, Peter Fogh; Trangbæk, Klaus
2006-01-01
This paper compares a selection of methods for detecting oscillations in control loops. The methods are tested on measurement data from a coal-fired power plant, where some oscillations are occurring. Emphasis is put on being able to detect oscillations without having a system model and without...
Scleronomic Holonomic Constraints and Conservative Nonlinear Oscillators
Munoz, R.; Gonzalez-Garcia, G.; Izquierdo-De La Cruz, E.; Fernandez-Anaya, G.
2011-01-01
A bead sliding, under the sole influence of its own weight, on a rigid wire shaped in the fashion of a plane curve, will describe (generally anharmonic) oscillations around a local minimum. For given shapes, the bead will behave as a harmonic oscillator in the whole range, such as an unforced, undamped, Duffing oscillator, etc. We also present…
Coherent states for the Legendre oscillator
Borzov, V. V.; Damaskinsky, E. V.
2003-01-01
A new oscillator-like system called by the Legendre oscillator is introduced in this note. The two families of coherent states (coherent states as eigenvectors of the annihilation operator and the Klauder-Gazeau temporally stable coherent states) are defined and investigated for this oscillator.
Slow oscillations orchestrating fast oscillations and memory consolidation.
Mölle, Matthias; Born, Jan
2011-01-01
Slow-wave sleep (SWS) facilitates the consolidation of hippocampus-dependent declarative memory. Based on the standard two-stage memory model, we propose that memory consolidation during SWS represents a process of system consolidation which is orchestrated by the neocortical memory. The slow oscillations temporally group neuronal activity into up-states of strongly enhanced neuronal activity and down-states of neuronal silence. In a feed-forward efferent action, this grouping is induced not only in the neocortex but also in other structures relevant to consolidation, namely the thalamus generating 10-15Hz spindles, and the hippocampus generating sharp wave-ripples, with the latter well known to accompany a replay of newly encoded memories taking place in hippocampal circuitries. The feed-forward synchronizing effect of the slow oscillation enables the formation of spindle-ripple events where ripples and accompanying reactivated hippocampal memory information become nested into the single troughs of spindles. Spindle-ripple events thus enable reactivated memory-related hippocampal information to be fed back to neocortical networks in the excitable slow oscillation up-state where they can induce enduring plastic synaptic changes underlying the effective formation of long-term memories. Copyright © 2011 Elsevier B.V. All rights reserved.
Measuring neutrino oscillation parameters using $\
Energy Technology Data Exchange (ETDEWEB)
Backhouse, Christopher James [Oriel College, Oxford (United Kingdom)
2011-01-01
MINOS is a long-baseline neutrino oscillation experiment. It consists of two large steel-scintillator tracking calorimeters. The near detector is situated at Fermilab, close to the production point of the NuMI muon-neutrino beam. The far detector is 735 km away, 716m underground in the Soudan mine, Northern Minnesota. The primary purpose of the MINOS experiment is to make precise measurements of the 'atmospheric' neutrino oscillation parameters (Δm_{atm}^{2} and sin^{2} 2θ_{atm}). The oscillation signal consists of an energy-dependent deficit of v_{μ} interactions in the far detector. The near detector is used to characterize the properties of the beam before oscillations develop. The two-detector design allows many potential sources of systematic error in the far detector to be mitigated by the near detector observations. This thesis describes the details of the v_{μ}-disappearance analysis, and presents a new technique to estimate the hadronic energy of neutrino interactions. This estimator achieves a significant improvement in the energy resolution of the neutrino spectrum, and in the sensitivity of the neutrino oscillation fit. The systematic uncertainty on the hadronic energy scale was re-evaluated and found to be comparable to that of the energy estimator previously in use. The best-fit oscillation parameters of the v_{μ}-disappearance analysis, incorporating this new estimator were: Δm^{2} = 2.32_{-0.08}^{+0.12} x 10^{-3} eV^{2}, sin ^{2} 2θ > 0.90 (90% C.L.). A similar analysis, using data from a period of running where the NuMI beam was operated in a configuration producing a predominantly $\\bar{v}$_{μ} beam, yielded somewhat different best-fit parameters Δ$\\bar{m}${sup 2} = (3.36_{-0.40}^{+0.46}(stat.) ± 0.06(syst.)) x 10^{-3}eV^{2}, sin^{2} 2$\\bar{θ}$ = 0.86_{-0.12}^{_0}
Time domain oscillating poles: Stability redefined in Memristor based Wien-oscillators
Talukdar, Abdul Hafiz Ibne
2012-07-28
Traditionally, the necessary and sufficient condition for any system to be oscillating is that its poles are located on the imaginary (jω) axis. In this paper, for the first time, we have shown that systems can oscillate with time-domain oscillating poles. The idea is verified using a Memristor based Wien oscillator. Sustained oscillations are observed without having the poles of the system fixed on the imaginary axis and the oscillating behavior of the system poles is reported. The oscillating resistance and triangular shape of FFT are also demonstrated with mathematical reasoning and simulation results to support the unusual and surprising characteristics. © 2009 IEEE.
DEFF Research Database (Denmark)
Köyluoglu, H.U.; Nielsen, Søren R.K.; Cakmak, A.S.
1994-01-01
The paper deals with the first and second order statistical moments of the response of linear systems with random parameters subject to random excitation modelled as white-noise multiplied by an envelope function with random parameters. The method of analysis is basically a second order perturbat......The paper deals with the first and second order statistical moments of the response of linear systems with random parameters subject to random excitation modelled as white-noise multiplied by an envelope function with random parameters. The method of analysis is basically a second order...... for multi-degree-of-freedom (MDOF) systems and the method is illustrated for a single-degree-of-freedom (SDOF) oscillator. The results are compared to those of exact results for a random oscillator subject to white noise excitation with random intensity....
Multifrequency Oscillator-Type Active Printed Antenna Using Chaotic Colpitts Oscillator
Bibha Kumari; Nisha Gupta
2014-01-01
This paper presents a new concept to realize a multifrequency Oscillator-type active printed monopole antenna. The concept of period doubling route to chaos is exploited to generate the multiple frequencies. The chaotic Colpitts oscillator is integrated with the printed monopole antenna (PMA) on the same side of the substrate to realize an Oscillator-type active antenna where the PMA acts as a load and radiator to the chaotic oscillator. By changing the bias voltage of the oscillator, the ant...
Experimental studies of neutrino oscillations
Kajita, Takaaki
2016-01-01
The 2015 Nobel Prize in physics has been awarded to Takaaki Kajita and Arthur McDonald "for the discovery of neutrino oscillations, which shows that neutrinos have mass". Takaaki Kajita of Tokyo University is a Japanese physicist, known for neutrino experiments at the Kamiokande and its successor, Super-Kamiokande. This volume of collected works of Kajita on neutrino oscillations provides a good glimpse into as well as a record of the rise and the role of Asian research in the frontiers of neutrino physics. Japan is now a major force in the study of the 3 families of neutrinos. Much remains to be done to clarify the Dirac vs. Majorana nature of the neutrino, and the cosmological implications of the neutrino. The collected works of Kajita and his Super-Kamiokande group will leave an indelible foot-print in the history of big and better science.
Cubication of conservative nonlinear oscillators
Energy Technology Data Exchange (ETDEWEB)
Belendez, Augusto; Alvarez, Mariela L [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, Elena; Pascual, Inmaculada [Departamento de Optica, FarmacologIa y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es
2009-09-15
A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear and cubic terms depend on the initial amplitude, A, while in a Taylor expansion of the restoring force these coefficients are independent of A. The replacement of the original nonlinear equation by an approximate Duffing equation allows us to obtain an approximate frequency-amplitude relation as a function of the complete elliptic integral of the first kind. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of this scheme.
Quantum transduction with mechanical oscillators
Lehnert, Konrad
In modern information technology, micromechanical oscillators are ubiquitous signal processing elements. Because the speed of sound is so slow compared to the speed of light, mechanical structures create superb compact filters and clocks. Moreover they convert force and acceleration signals into more easily processed electrical signals. Although these humble devices appear manifestly classical, they can exhibit quantum behavior when their vibrations are strongly coupled to optical light or to microwave electricity. I will describe our progress in using this recent result to develop quantum information processing elements. First, we are developing a device that uses a mechanical oscillator to transfer information noiselessly between electrical and optical domains. Second, we prepare propagating microwave fields in superpositions of 0 and 1 photon, and use an electromechanical device to store and amplify these fragile quantum bits. Work supported by AFOSR MURI:FA9550-15-1-0015, NSF under Grant Number 1125844, and the Gordon and Betty Moore Foundation.
Memristor-based reactance-less oscillator
Zidan, Mohammed A.
2012-10-02
The first reactance-less oscillator is introduced. By using a memristor, the oscillator can be fully implemented on-chip without the need for any capacitors or inductors, which results in an area-efficient fully integrated solution. The concept of operation of the proposed oscillator is explained and detailed mathematical analysis is introduced. Closed-form expressions for the oscillation frequency and oscillation conditions are derived. Finally, the derived equations are verified with circuit simulations showing excellent agreement. © 2011 The Institution of Engineering and Technology.
Cyanohydrin reactions enhance glycolytic oscillations in yeast
DEFF Research Database (Denmark)
Hald, Bjørn Olav; Nielsen, Astrid Gram; Tortzen, Christian
2015-01-01
Synchronous metabolic oscillations can be induced in yeast by addition of glucose and removal of extracellular acetaldehyde (ACAx). Compared to other means of ACAx removal, cyanide robustly induces oscillations, indicating additional cyanide reactions besides ACA to lactonitrile conversion. Here...... for ~66% of total cyanide removal. Simulations of our updated computational model show that intracellular cyanide reactions increase the amplitude of oscillations and that cyanide addition lowers [ACA] instantaneously. We conclude that cyanide provides the following means of inducing global oscillations......: a) by reducing [ACAx] relative to oscillation amplitude, b) by targeting multiple intracellular carbonyl compounds during fermentation, and c) by acting as a phase resetting stimulus....
Multipartite entanglement in neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Blasone, Massimo; Dell' Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio, E-mail: blasone@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)
2009-06-01
Particle mixing is related to multi-mode entanglement of single-particle states The occupation number of both flavor eigenstates and mass eigenstates can be used to define a multiqubit space. In such a framework, flavor neutrino states can be interpreted as multipartite mode-entangled states. By using two different entanglement measures, we analyze the behavior of multipartite entanglement in the phenomenon of neutrino oscillations.
Oscillations and Waves in Sunspots
Directory of Open Access Journals (Sweden)
Elena Khomenko
2015-11-01
Full Text Available A magnetic field modifies the properties of waves in a complex way. Significant advances have been made recently in our understanding of the physics of sunspot waves with the help of high-resolution observations, analytical theories, as well as numerical simulations. We review the current ideas in the field, providing the most coherent picture of sunspot oscillations as by present understanding.
Renormalization for free harmonic oscillators
Sonoda, H.
2013-01-01
We introduce a model of free harmonic oscillators that requires renormalization. The model is similar to but simpler than the soluble Lee model. We introduce two concrete examples: the first, resembling the three dimensional $\\phi^4$ theory, needs only mass renormalization, and the second, resembling the four dimensional $\\phi^4$ theory and the Lee model, needs additional renormalization of a coupling and a wave function.
Oscillations of a polarizable vacuum
Directory of Open Access Journals (Sweden)
James G. Gilson
1991-01-01
Full Text Available A classical basis for one-dimensional Schrödinger quantum theory is constructed from simple vacuum polarization harmonic oscillators within standard stochastic theory. The model is constructed on a two-dimensional phase configuration surface with phase velocity vectors that have a speed of light zitterbewegung behaviour character. The system supplies a natural Hermitian scalar product describing probability density which is derived from angular momentum considerations. The generality of the model which is extensive is discussed.
Automatic oscillator frequency control system
Smith, S. F. (Inventor)
1985-01-01
A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.
Neutrino Oscillation Experiment at JHF
2002-01-01
T2K is a long baseline neutrino experiment designed to investigate how neutrinos change from one flavor to another as they travel (neutrino oscillations). An intense beam of muon neutrinos is generated at the J-PARC nuclear physics site on the East coast of Japan and directed across the country to the Super-Kamiokande neutrino detector in the mountains of western Japan. The beam is measured once before it leaves the J-PARC site, using the near detector ND280, and again at Super-K, 295 km away: the change in the measured intensity and composition of the beam is used to provide information on the properties of neutrinos. The high intensity neutrino beam is produced in an off-axis configuration. The peak neutrino energy is tuned to the oscillation maximum of ∼ 0.6 GeV to maximize the sensitivity to neutrino oscillations. The science goals of T2K can be summarized as follows: •\tsearch for CP violation in the neutrino sector •\tdiscovery of νμ → νe ( i.e. the confirmation that θ13 > 0 ) •\tprecision ...
Capacitive coupling synchronizes autonomous microfluidic oscillators.
Lesher-Perez, Sasha Cai; Zhang, Chao; Takayama, Shuichi
2018-01-31
Even identically-designed autonomous microfluidic oscillators have device-to-device oscillation variability that arises due to inconsistencies in fabrication, materials, and operation conditions. This work demonstrates, experimentally and theoretically, that with appropriate capacitive coupling these microfluidic oscillators can be synchronized. The size and characteristics of the capacitive coupling needed and the range of input flow rate differences that can be synchronized are also characterized. In addition to device-to-device variability, there is also within-device oscillation noise that arises. An additional advantage of coupling multiple fluidic oscillators together is that the oscillation noise decreases. The ability to synchronize multiple autonomous oscillators is also a first step towards enhancing their usefulness as tools for biochemical research applications where multiplicate experiments with identical temporal-stimulation conditions are required. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Microwave balanced oscillators and frequency doublers
Siripon, N
2002-01-01
The research presented in this thesis is on the application of the injection-locked oscillator technique to microwave balanced oscillators. The balanced oscillator design is primarily analysed using the extended resonance technique. A transmission line is connected between the two active devices, so that the active device resonate each other. The electrical length of the transmission line is also analysed for the balanced oscillation condition. The balanced oscillator can be viewed with the negative resistance model and the feedback model. The former model is characterised at a circuit plane where the feedback network is cut. By using both the negative-resistance oscillator model and the feedback model, the locking range of the oscillator is analysed by extending Kurokawa's theory. This analysis demonstrates the locking range of the injection phenomenon, where the injection frequency is either close to the free-running frequency, close to (1/n) x free-running frequency or close to n x the free-running frequen...
Measurement of b_s oscillations at CDF
Energy Technology Data Exchange (ETDEWEB)
Salamanna, G.; /Rome U. /INFN, Rome
2006-09-01
The first precise measurement of the B{sub s}{sup 0} - {bar B}{sub s}{sup 0} oscillation frequency {Delta}m{sub s} with the CDFII experiment is summarized in this talk. The measurement is performed with 1 fb{sup -1} of data collected at the Fermilab Tevatron hadron collider. They find a signal consistent with flavor oscillations; the probability that such a signal is originated by random fluctuations is 0.2%. They measure {Delta}m{sub s} = 17.31{sub -0.18}{sup +0.33}(stat.) {+-} 0.07(syst.)ps{sup -1}. After a brief theoretical overview, the author describes the experimental technique and shows the results of the CDF analysis and the |V{sub td}/V{sub ts}| value we infer from this measurement.
Backward Wave Oscillation Thresholds in a Traveling-Wave Tube
Jassem, Abhijit; Wong, Patrick; Antoulinakis, Foivos; Lau, Y. Y.
2017-10-01
The threshold for the onset of backward wave oscillation (BWO) in a traveling-wave tube (TWT) was formulated by Johnson. In this paper, we extend Johnson's model to include random variations of circuit phase velocity along the tube axis. We find that Johnson's BWO threshold is minimally affected by these random variations. We next ignore these random variations, but include finite reflections at the two ends of a TWT and study their effects on Johnson's threshold. The latter theory is developed and being compared with results from an experimental helix test circuit. We will explore a 4-wave treatment for BWO, and its connection with the Briggs-Bers criterion for the existence of absolute instability. Work supported by DARPA, contract HR0011-16-C-0080 with Leidos, Inc., AFOSR Awards Nos. FA9550-15-1-0097, FA9550-14-1-0309, and L-3 Communications.
Separation control with fluidic oscillators in water
Schmidt, H.-J.; Woszidlo, R.; Nayeri, C. N.; Paschereit, C. O.
2017-08-01
The present study assesses the applicability of fluidic oscillators for separation control in water. The first part of this work evaluates the properties of the fluidic oscillators including frequency, cavitation effects, and exerted thrust. Derived from the governing internal dynamics, the oscillation frequency is found to scale directly with the jet's exit velocity and the size of the fluidic oscillator independent of the working fluid. Frequency data from various experiments collapse onto a single curve. The occurrence of cavitation is examined by visual inspection and hydrophone measurements. The oscillation frequency is not affected by cavitation because it does not occur inside the oscillators. The spectral information obtained with the hydrophone provide a reliable indicator for the onset of cavitation at the exit. The performance of the fluidic oscillators for separation control on a bluff body does not seem to be affected by the presence of cavitation. The thrust exerted by an array of fluidic oscillators with water as the working fluid is measured to be even larger than theoretically estimated values. The second part of the presented work compares the performance of fluidic oscillators for separation control in water with previous results in air. The array of fluidic oscillators is installed into the rear end of a bluff body model. The drag improvements based on force balance measurements agree well with previous wind tunnel experiments on the same model. The flow field is examined by pressure measurements and with particle image velocimetry. Similar performance and flow field characteristics are observed in both water and air.
Stochastic Multiresonance for a Fractional Linear Oscillator with Quadratic Trichotomous Noise
Zhu, Jian-Qu; Jin, Wei-Dong; Zheng, Gao; Guo, Feng
2017-11-01
The stochastic multiresonance behavior for a fractional linear oscillator with random system frequency is investigated. The fluctuation of the system frequency is a quadratic trichotomous noise, the memory kernel of the fractional oscillator is modeled as a Mittag–Leffler function. Based on linear system theory, applying Laplace transform and the definition of fractional derivative, the expression of the system output amplitude (SPA) is obtained. Stochastic multiresonance phenomenon is found on the curves of SPA versus the memory time and the memory exponent of the fractional oscillator, as well as versus the trichotomous noise amplitude. The SPA depends non-monotonically on the stationary probability of the trichotomous noise, on the viscous damping coefficient and system characteristic frequency of the oscillator, as well as on the driving frequency of external force. Supported by National Natural Science Foundation of China under Grant No. 61134002
Tian, Da-Sheng; Jing, Jue-Hua; Qian, Jun; Chen, Lei; Zhu, Bin
2016-05-01
[Purpose] The aim of this study was to evaluate the effect of oscillating electrical field stimulation on motor function recovery and myelin regeneration in rats with spinal cord injury. [Subjects and Methods] A rat model of spinal cord injury was constructed by using the Allen weight-drop method. These rats were randomly divided into normal, spinal cord injury, and spinal cord injury + oscillating electrical field stimulation groups. The experimental group received the intervention with oscillating electrical field stimulation, and the control group received the intervention with an electrical field stimulator without oscillating electrical field stimulation. Each group was then randomly divided into seven subgroups according to observation time (1, 2, 4, 6, 8, 10, and 12 weeks). Basso-Beattie-Bresnahan score and inclined plate test score evaluation, motor evoked potential detection, and histological observation were performed. [Results] In the first 2 weeks of oscillating electrical field stimulation, the oscillating electrical field stimulation and inclined plate test scores of spinal cord injury group and spinal cord injury + oscillating electrical field stimulation group were not significantly different. In the fourth week, the scores of the spinal cord injury group were significantly lower than those of the spinal cord injury + oscillating electrical field stimulation group. The motor evoked potential incubation period in the spinal cord injury + oscillating electrical field stimulation group at the various time points was shorter than that in the spinal cord injury group. In the sixth week, the relative area of myelin in the spinal cord injury + oscillating electrical field stimulation group was evidently larger than that in the spinal cord injury group. [Conclusion] Oscillating electrical field stimulation could effectively improve spinal cord conduction function and promote motor function recovery in rats with spinal cord injury, as well as promote myelin
Waves and Oscillations in Plasmas
Pecseli, Hans L
2012-01-01
The result of more than 15 years of lectures in plasma sciences presented at universities in Denmark, Norway, and the United States, Waves and Oscillations in Plasmas addresses central issues in modern plasma sciences. The book covers fluid models as well as kinetic plasma models, including a detailed discussion of, for instance, collisionless Landau damping. Offering a clear separation of linear and nonlinear models, the book can be tailored for readers of varying levels of expertise.Designed to provide basic training in linear as well as nonlinear plasma dynamics, and practical in areas as d
Pair creation and plasma oscillations.
Energy Technology Data Exchange (ETDEWEB)
Prozorkevich, A. V.; Vinnik, D. V.; Schmidt, S. M.; Hecht, M. B.; Roberts, C. D.
2000-12-15
We describe aspects of particle creation in strong fields using a quantum kinetic equation with a relaxation-time approximation to the collision term. The strong electric background field is determined by solving Maxwell's equation in tandem with the Vlasov equation. Plasma oscillations appear as a result of feedback between the background field and the field generated by the particles produced. The plasma frequency depends on the strength of the initial background fields and the collision frequency, and is sensitive to the necessary momentum-dependence of dressed-parton masses.
Wave Physics Oscillations - Solitons - Chaos
Nettel, Stephen
2009-01-01
This textbook is intended for those second year undergraduates in science and engineering who will later need an understanding of electromagnetic theory and quantum mechanics. The classical physics of oscillations and waves is developed at a more advanced level than has been customary for the second year, providing a basis for the quantum mechanics that follows. In this new edition the Green's function is explained, reinforcing the integration of quantum mechanics with classical physics. The text may also form the basis of an "introduction to theoretical physics" for physics majors. The concluding chapters give special attention to topics in current wave physics: nonlinear waves, solitons, and chaotic behavior.
Making space for harmonic oscillators
Energy Technology Data Exchange (ETDEWEB)
Michelotti, Leo; /Fermilab
2004-11-01
If we restrict the number of harmonic oscillator energy eigenstates to some finite value, N, then the discrete spectrum of the corresponding position operator comprise the roots of the Hermite polynomial H{sub N+1}. Its range is just large enough to accommodate classical motion at high energy. A negative energy term must be added to the Hamiltonian which affects only the last eigenstate, |N>, suggesting it is concentrated at the extrema of this finite ''space''. Calculations support a conjecture that, in the limit of large N, the global distribution of points approaches the differential form for classical action.
Neutrino Oscillation Studies with Reactors
Vogel, Petr; Zhang, Chao
2015-01-01
Nuclear reactors are one of the most intense, pure, controllable, cost-effective, and well-understood sources of neutrinos. Reactors have played a major role in the study of neutrino oscillations, a phenomenon that indicates that neutrinos have mass and that neutrino flavors are quantum mechanical mixtures. Over the past several decades reactors were used in the discovery of neutrinos, were crucial in solving the solar neutrino puzzle, and allowed the determination of the smallest mixing angle $\\theta_{13}$. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.
Phase noise and frequency stability in oscillators
Rubiola, Enrico
2009-01-01
Presenting a comprehensive account of oscillator phase noise and frequency stability, this practical text is both mathematically rigorous and accessible. An in-depth treatment of the noise mechanism is given, describing the oscillator as a physical system, and showing that simple general laws govern the stability of a large variety of oscillators differing in technology and frequency range. Inevitably, special attention is given to amplifiers, resonators, delay lines, feedback, and flicker (1/f) noise. The reverse engineering of oscillators based on phase-noise spectra is also covered, and end-of-chapter exercises are given. Uniquely, numerous practical examples are presented, including case studies taken from laboratory prototypes and commercial oscillators, which allow the oscillator internal design to be understood by analyzing its phase-noise spectrum. Based on tutorials given by the author at the Jet Propulsion Laboratory, international IEEE meetings, and in industry, this is a useful reference for acade...
Acoustic Oscillation Properties of Active Region 12193
Monsue, Teresa; Pesnell, William D.; Hill, Frank
2017-08-01
Solar flares are dynamic objects occurring randomly and yet unannounced in nature. In order to find an efficient detection method, we require a greater breadth of knowledge of the system. One path to such a method is to observe the solar atmosphere in a region around a flare in different wavelengths of light and acoustic frequency bands. This provides information from different altitudes in the solar atmosphere and allows us to study the temporal evolution of each altitude through the flaring event. A more complete understanding of the time evolution may lead to yet undiscovered precursors of the flare. In this project, we study Active Region 12192 using acoustic observations near an X3 flare occurring on October 24, 2014 at 21:41UT. Our wavelet analysis utilizes time series data to create Fourier power spectra of individual pixels spatially resolved around the flare region, to study the frequency bands. In order to study the power distribution in regions around the flare and to search for any correlation we apply several methods. One method we partition sub-regions in our main flaring region and take a survey of the oscillations for each frequency band within power maps. Another method we average the FFT to take measurements within the p-modes (2-4 mHz) and chromospheric (4-6 mHz) frequencies. The application of these methods should be able to get us closer to tracking waveforms within power maps.
The geodynamo as a bistable oscillator
Hoyng, P.; Ossendrijver, M. A. J. H.; Schmitt, D.
2001-07-01
Our intent is to provide a simple and quantitative understanding of the variability of the axial dipole component of the geomagnetic field on both short and long time scales. To this end we study the statistical properties of a prototype nonlinear mean field model. An azimuthal average is employed, so that (1) we address only the axisymmetric component of the field, and (2) the dynamo parameters have a random component that fluctuates on the (fast) eddy turnover time scale. Numerical solutions with a rapidly fluctuating alpha reproduce several features of the geomagnetic field: (1) a variable, dominantly dipolar field with additional fine structure due to excited overtones, and sudden reversals during which the field becomes almost quadrupolar, (2) aborted reversals and excursions, (3) intervals between reversals having a Poisson distribution. These properties are robust, and appear regardless of the type of nonlinearity and the model parameters. A technique is presented for analysing the statistical properties of dynamo models of this type. The Fokker-Planck equation for the amplitude a of the fundamental dipole mode shows that a behaves as the position of a heavily damped particle in a bistable potential ~(1-a^2)^2, subject to random forcing. The dipole amplitude oscillates near the bottom of one well and makes occasional jumps to the other. These reversals are induced solely by the overtones. Theoretical expressions are derived for the statistical distribution of the dipole amplitude, the variance of the dipole amplitude between reversals, and the mean reversal rate. The model explains why the reversal rate increases with increasing secular variation, as observed. Moreover, the present reversal rate of the geodynamo, once per (2-3)x10^5years, is shown to imply a secular variation of the dipole moment of ~15% (about the current value). The theoretical dipole amplitude distribution agrees well with the Sint-800 data.
Modes of nanosatellite aerodynamic oscillations in atmosphere
Gerasimov, Yu V.; Ivanov, E. A.; Karetnikov, G. K.; Konstantinova, I. A.; Selivanov, A. B.
2017-11-01
The paper is devoted to the results of investigating the dependencies of nanosatellite aerodynamic oscillations frequency on attack angle at different altitudes up to 70 km are defined. The oscillations bandwidths are determined with respect to the geometric parameters for a nanosatellite with 10 kg mass and 6000 kg/m3 average density. The model allows estimating the bandwidth aerodynamic oscillations in the suborbital nanosatellite trajectory based on the given geometry and mass-dimensional parameters.
Oscillations of neutral B mesons systems
Boucrot, J
1999-01-01
The oscillation phenomenon in the neutral B mesons systems is now well established. The motivations and principles of the measurements are given; then the most recent results from the LEP experiments, the CDF collaboration at Fermilab and the SLD collaboration at SLAC are reviewed. The present world average of the $\\bd$ meson oscillation frequency is $\\dmd = 0.471 \\pm 0.016 \\ps$ and the lower limit on the $\\bs$ oscillation frequency is
Phase-locked Josephson soliton oscillators
DEFF Research Database (Denmark)
Holst, T.; Hansen, Jørn Bindslev; Grønbech-Jensen, N.
1991-01-01
Detailed experimental characterization of the phase-locking at both DC and at microwave frequencies is presented for two closely spaced Josephson soliton (fluxon) oscillators. In the phase-locked state, the radiated microwave power exhibited an effective gain. With one common bias source......, a frequency tunability of the phase-locked oscillators up to 7% at 10 GHz was observed. The interacting soliton oscillators were modeled by two inductively coupled nonlinear transmission lines...
On Rabi oscillations between Bloch bands
Plötz, Patrick
2010-01-01
We study Rabi oscillations between the bands of an arbitrary biased superlattice in a tight-binding model. We reduce the problem to an equation of Whittaker--Hill type and, in absence of any known solutions in closed form, discuss different approximations to describe the oscillations between the Bloch bands. We identify regimes of weak and strong inter-band coupling and compare predictions for these Rabi oscillations to numerical results.
SPIRAL, FUNCTIONS AND OSCILLATING SYSTEMS BESSEL
Gil Benitez, W.; Universidad Nacional Mayor de San Marcos, Facultad de Química e Ingeniería Química Departamento de Analisis y Diseño de Procesos Av. Venezuela sin - Ciudad Universitaria UNMSM - Lima - Peru
2014-01-01
lt is shown a mathematics analysis that link spirals, differential equations of second order of the Bessel function type and the oscillant systems with constant and variable frequency. lt is found that the oscillant systems are consecuents to a spiral mathematical functions and Bessel is only some of its varieties. Consequently is shown an exact solution of the Bessel equations which does l'lot require tables. The math model it is a tool which will be used to simulate oscillant phenomena with...
Small oscillations via conservation of energy
Troy, Tia; Reiner, Megan; Haugen, Andrew J.; Moore, Nathan T.
2017-11-01
The work describes an analogy-based small oscillations analysis of a standard static equilibrium lab problem. In addition to force analysis, a potential energy function for the system is developed, and by drawing out mathematical similarities to the simple harmonic oscillator, we are able to describe (and experimentally verify) the period of small oscillations about the static equilibrium state. The problem was developed and implemented in a standard University Physics course at Winona State University.
Q-oscillators and relativistic position operators
Energy Technology Data Exchange (ETDEWEB)
Arik, M. (Dept. of Mathematics, Istanbul Technical Univ. (Turkey)); Mungan, M. (Dept. of Physics, Bogazici Univ., Istanbul (Turkey))
1992-05-21
We investigate the multi-dimensional q-oscillator whose commutation relations are invariant under the quantum group. The no-interaction limit corresponds to a contraction of the q-oscillator algebra and yields relativistic position operators which can be expressed in terms of the generators of the Poincare group. This leads to the interpretation of the interacting q-oscillator as an relativistic quantum system and results in a hamiltonian whose spectrum is exactly exponential. (orig.).
Toward precision study of atmospheric neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Kajita, Takaaki [Research Center for Cosmic Neutrinos, Institute for Cosmic Ray Research, Univ. of Tokyo, Kashiwa-no-ha 5-1-5, Kashiwa, Chiba 277-8582 (Japan)
2006-09-15
Atmospheric neutrinos have been playing a major role in studying neutrino oscillations. Because of the unique feature of atmospheric neutrinos, future atmospheric neutrino experiments are likely to contribute to precision studies of neutrino oscillations. Possible contribution of future atmospheric neutrino experiments to the neutrino oscillation physics are discussed, including the measurements of {theta}{sub 13}, the sign of {delta}m{sub 23}{sup 2}, the determination of octant of {theta}{sub 23} and possibly the CP phase.
Spinning Photons and Twisting Oscillators
Shi, Hao
2014-05-01
Optomechanics is the study of the interaction between optical radiation and mechanical motion. Typically, an optomechanical system is composed of an optical resonator coupled to a mechanical degree of freedom. Some of the most striking experimental achievements include the quantum ground state preparation for a macroscopic oscillator, the detection of optomechanical quantum back-action, and generation of optomechanically induced transparency and slow light. Most optomechanical systems depend on linear coupling between the optical field and the displacement of the mechanical oscillator. In this talk, I will start instead by discussing the basic quantum mechanics of a generic quadratically coupled optomechanical system, followed by our efforts towards extending optomechanics to torsional and rotational systems. Specifically, I will describe our theoretical proposal to couple a windmill-shaped dielectric to cavity Laguerre Gaussian modes. In addition, I will present an optoacoustic system, composed of a LG mode coupled t surface acoustic waves of a spherical mirror, as a new platform for storage of photons carrying orbital angular momentum. Finally, I will discuss our most recent investigation of the prospects of cooling full rotational motion to the quantum regime.
Cardiogenic oscillation induced ventilator autotriggering
Directory of Open Access Journals (Sweden)
Narender Kaloria
2015-01-01
Full Text Available Cardiogenic oscillation during mechanical ventilation can auto-trigger the ventilator resembling patient initiated breadth. This gives a false sense of intact respiratory drive and determination brain death, even if other tests are positive, is not appropriate in such a situation. It will prolong the ICU stay and confound the brain-death determination. In this case report, we describe a 35 year old man who was brought to the hospital after many hours of critical delay following multiple gun shot injuries. The patient suffered a cardiac arrest while on the way from another hospital. After an emergency laparotomy, patient was shifted to Intensive Care Unit (ICU with Glasgow Coma Scale (GCS score of E1VTM1 and was mechanically ventilated. Despite absence of brainstem reflexes, the ventilator continued to be triggered on continuous positive airway pressure (CPAP mode and the patient maintained normal oxygen saturation and acceptable levels of carbon dioxide. An apnoea test confirmed absent respiratory drive. Ventilatory waveform graph analysis, revealed cardiogenic oscillation as the cause for autotrigerring.
Microdroplet oscillations during optical pulling
Ellingsen, Simen A.˚.
2012-02-01
It was recently shown theoretically that it is possible to pull a spherical dielectric body towards the source of a laser beam [J. Chen, J. Ng, Z. Lin, and C. T. Chan, "Optical pulling force," Nat. Photonics 5, 531 (2011)], a result with immediate consequences to optical manipulation of small droplets. Optical pulling can be realized, e.g., using a diffraction-free Bessel beam, and is expected to be of great importance in manipulation of microscopic droplets in micro- and nanofluidics. Compared to conventional optical pushing, however, the ratio of optical net force to stress acting on a droplet is much smaller, increasing the importance of oscillations. We describe the time-dependent surface deformations of a water microdroplet under optical pulling to linear order in the deformation. Shape oscillations have a lifetime in the order of microseconds for droplet radii of a few micrometers. The force density acting on the initially spherical droplet is strongly peaked near the poles on the beam axis, causing the deformations to take the form of jet-like protrusions.
Nonlinear nanomechanical oscillators for ultrasensitive inertial detection
Datskos, Panagiotis George; Lavrik, Nickolay V
2013-08-13
A system for ultrasensitive mass and/or force detection of this invention includes a mechanical oscillator driven to oscillate in a nonlinear regime. The mechanical oscillator includes a piezoelectric base with at least one cantilever resonator etched into the piezoelectric base. The cantilever resonator is preferably a nonlinear resonator which is driven to oscillate with a frequency and an amplitude. The system of this invention detects an amplitude collapse of the cantilever resonator at a bifurcation frequency as the cantilever resonator stimulated over a frequency range. As mass and/or force is introduced to the cantilever resonator, the bifurcation frequency shifts along a frequency axis in proportion to the added mass.
Introduction to classical and quantum harmonic oscillators
Bloch, Sylvan C
2013-01-01
From conch shells to lasers . harmonic oscillators, the timeless scientific phenomenon As intriguing to Galileo as they are to scientists today, harmonic oscillators have provided a simple and compelling paradigm for understanding the complexities that underlie some of nature's and mankind's most fascinating creations. From early string and wind instruments fashioned from bows and seashells to the intense precision of lasers, harmonic oscillators have existed in various forms, as objects of beauty and scientific use. And harmonic oscillation has endured as one of science's most fascinating con
High Reliability Oscillators for Terahertz Systems Project
National Aeronautics and Space Administration — Terahertz sources based on lower frequency oscillators and amplifiers plus a chain of frequency multipliers are the workhorse technology for NASA's terahertz...
Waves and oscillations in nature an introduction
Narayanan, A Satya
2015-01-01
Waves and oscillations are found in large scales (galactic) and microscopic scales (neutrino) in nature. Their dynamics and behavior heavily depend on the type of medium through which they propagate.Waves and Oscillations in Nature: An Introduction clearly elucidates the dynamics and behavior of waves and oscillations in various mediums. It presents different types of waves and oscillations that can be observed and studied from macroscopic to microscopic scales. The book provides a thorough introduction for researchers and graduate students in assorted areas of physics, such as fluid dynamics,
Stochastic Kuramoto oscillators with discrete phase states
Jörg, David J.
2017-09-01
We present a generalization of the Kuramoto phase oscillator model in which phases advance in discrete phase increments through Poisson processes, rendering both intrinsic oscillations and coupling inherently stochastic. We study the effects of phase discretization on the synchronization and precision properties of the coupled system both analytically and numerically. Remarkably, many key observables such as the steady-state synchrony and the quality of oscillations show distinct extrema while converging to the classical Kuramoto model in the limit of a continuous phase. The phase-discretized model provides a general framework for coupled oscillations in a Markov chain setting.
Scleronomic holonomic constraints and conservative nonlinear oscillators
Energy Technology Data Exchange (ETDEWEB)
Munoz, R; Gonzalez-Garcia, G; Izquierdo-De La Cruz, E Izquierdo-De La [Universidad Autonoma de la Ciudad de Mexico, Centro Historico, Fray Servando Teresa de Mier 92, Col Centro, Del Cuauhtemoc, Mexico DF, CP 06080 (Mexico); Fernandez-Anaya, G, E-mail: rodrigo.munoz@uacm.edu.mx, E-mail: gggharper@gmail.com, E-mail: erickidc@gmail.com, E-mail: guillermo.fernandez@uia.mx [Universidad Iberoamericana, Departamento de Fisica y Matematicas, Prolongacon Paseo de de la Reforma 880, Col Lomas de Santa Fe, Del Alvaro Obregn, Mexico DF, CP 01219 (Mexico)
2011-05-15
A bead sliding, under the sole influence of its own weight, on a rigid wire shaped in the fashion of a plane curve, will describe (generally anharmonic) oscillations around a local minimum. For given shapes, the bead will behave as a harmonic oscillator in the whole range, such as an unforced, undamped, Duffing oscillator, etc. We also present cases in which the effective potential acting on the bead is not analytical around a minimum. The small oscillation approximation cannot be applied to such pathological cases. Nonetheless, these latter instances are studied with other standard techniques.
Elements of biological oscillations in time and space.
Cao, Yangxiaolu; Lopatkin, Allison; You, Lingchong
2016-12-06
Oscillations in time and space are ubiquitous in nature and play critical roles in dynamic cellular processes. Although the molecular mechanisms underlying the generation of the dynamics are diverse, several distinct regulatory elements have been recognized as being critical in producing and modulating oscillatory dynamics. These include negative and positive feedback, time delay, nonlinearity in regulation, and random fluctuations ('noise'). Here we discuss the specific roles of these five elements in promoting or attenuating oscillatory dynamics, by drawing on insights from quantitative analyses of natural or synthetic biological networks.
Edgington, Eugene
2007-01-01
Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani
A coupled-oscillator model of olfactory bulb gamma oscillations.
Directory of Open Access Journals (Sweden)
Guoshi Li
2017-11-01
Full Text Available The olfactory bulb transforms not only the information content of the primary sensory representation, but also its underlying coding metric. High-variance, slow-timescale primary odor representations are transformed by bulbar circuitry into secondary representations based on principal neuron spike patterns that are tightly regulated in time. This emergent fast timescale for signaling is reflected in gamma-band local field potentials, presumably serving to efficiently integrate olfactory sensory information into the temporally regulated information networks of the central nervous system. To understand this transformation and its integration with interareal coordination mechanisms requires that we understand its fundamental dynamical principles. Using a biophysically explicit, multiscale model of olfactory bulb circuitry, we here demonstrate that an inhibition-coupled intrinsic oscillator framework, pyramidal resonance interneuron network gamma (PRING, best captures the diversity of physiological properties exhibited by the olfactory bulb. Most importantly, these properties include global zero-phase synchronization in the gamma band, the phase-restriction of informative spikes in principal neurons with respect to this common clock, and the robustness of this synchronous oscillatory regime to multiple challenging conditions observed in the biological system. These conditions include substantial heterogeneities in afferent activation levels and excitatory synaptic weights, high levels of uncorrelated background activity among principal neurons, and spike frequencies in both principal neurons and interneurons that are irregular in time and much lower than the gamma frequency. This coupled cellular oscillator architecture permits stable and replicable ensemble responses to diverse sensory stimuli under various external conditions as well as to changes in network parameters arising from learning-dependent synaptic plasticity.
Early Oscillation Detection for DC/DC Converter Fault Diagnosis
Wang, Bright L.
2011-01-01
The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.
Energy funneling in a bent chain of Morse oscillators with long-range coupling
DEFF Research Database (Denmark)
Larsen, Peter Ulrik Vingaard; Christiansen, Peter Leth; Bang, Ole
2004-01-01
A bent chain of coupled Morse oscillators with long-range dispersive interaction is considered. Moving localized excitations may be trapped in the bending region. Thus chain geometry acts like an impurity. An energy funneling effect is observed in the case of random initial conditions....
The Bethe Sum Rule and Basis Set Selection in the Calculation of Generalized Oscillator Strengths
DEFF Research Database (Denmark)
Cabrera-Trujillo, Remigio; Sabin, John R.; Oddershede, Jens
1999-01-01
Fulfillment of the Bethe sum rule may be construed as a measure of basis set quality for atomic and molecular properties involving the generalized oscillator strength distribution. It is first shown that, in the case of a complete basis, the Bethe sum rule is fulfilled exactly in the random phase...
Oscillating water column structural model
Energy Technology Data Exchange (ETDEWEB)
Copeland, Guild [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jepsen, Richard Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-09-01
An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by a BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.
Signal velocity in oscillator arrays
Cantos, C. E.; Veerman, J. J. P.; Hammond, D. K.
2016-09-01
We investigate a system of coupled oscillators on the circle, which arises from a simple model for behavior of large numbers of autonomous vehicles where the acceleration of each vehicle depends on the relative positions and velocities between itself and a set of local neighbors. After describing necessary and sufficient conditions for asymptotic stability, we derive expressions for the phase velocity of propagation of disturbances in velocity through this system. We show that the high frequencies exhibit damping, which implies existence of well-defined signal velocitiesc+ > 0 and c- < 0 such that low frequency disturbances travel through the flock as f+(x - c+t) in the direction of increasing agent numbers and f-(x - c-t) in the other.
Oscillating spin-2 dark matter
Marzola, Luca; Raidal, Martti; Urban, Federico R.
2018-01-01
The negative outcomes of laboratory searches, juxtaposed with cosmological observations, may indicate that dark matter has a gravitational origin. We show that coherent oscillations of a massive spin-2 field emerging from bimetric theory can easily account for the observed dark matter abundance. The framework, based on the only known consistent extension of general relativity to interacting spin-2 fields, is testable in precision measurements of the electric charge variation by means of atomic clocks, molecular systems, dedicated resonant mass detectors, as well as gravity interferometers and axionlike-particle experiments. These searches, therefore, provide a new window into the phenomenology of gravity which complements the results of dedicated tests of gravitation. We also present a multimetric extension of the scenario that straightforwardly implements the clockwork mechanism for gravity, explaining the apparent weakness of this force.
Analysing Biochemical Oscillations through Probabilistic Model Checking
DEFF Research Database (Denmark)
Ballarini, Paolo; Mardare, Radu Iulian; Mura, Ivan
2009-01-01
Analysing Biochemical Oscillations through Probabilistic Model Checking. In Proc. of the Second International Workshop "From Biology To Concurrency" (FBTC 2008), Electronic Notes in Theoretical Computer Science......Analysing Biochemical Oscillations through Probabilistic Model Checking. In Proc. of the Second International Workshop "From Biology To Concurrency" (FBTC 2008), Electronic Notes in Theoretical Computer Science...
Electromagnetic Radiation Originating from Unstable Electron Oscillations
DEFF Research Database (Denmark)
Juul Rasmussen, Jens; Pécseli, Hans
1975-01-01
Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function.......Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function....
Stabilizing oscillating universes against quantum decay
Mithani, Audrey T.; Vilenkin, Alexander
2015-07-01
We investigate the effect of vacuum corrections, due to the trace anomaly and Casimir effect, on the stability of an oscillating universe with respect to decay by tunneling to the singularity. We find that these corrections do not generally stabilize an oscillating universe. However, stability may be achieved for some specially fine-tuned non-vacuum states.
Neutrino mass and oscillation: An introductory review
Indian Academy of Sciences (India)
tion to the atmospheric and solar neutrino oscillation data requires only two right handed singlet neutrinos. 2. Neutrino mixing and oscillation (vacuum). If the neutrinos have nonzero mass, there will in general be mixing between the neutrino species as in the case of quarks. For most practical applications it is adequate to ...
Chaos in nonlinear oscillations controlling and synchronization
Lakshamanan, M
1996-01-01
This book deals with the bifurcation and chaotic aspects of damped and driven nonlinear oscillators. The analytical and numerical aspects of the chaotic dynamics of these oscillators are covered, together with appropriate experimental studies using nonlinear electronic circuits. Recent exciting developments in chaos research are also discussed, such as the control and synchronization of chaos and possible technological applications.
Stabilizing oscillating universes against quantum decay
Energy Technology Data Exchange (ETDEWEB)
Mithani, Audrey T.; Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy,Tufts University, Medford, MA 02155 (United States)
2015-07-07
We investigate the effect of vacuum corrections, due to the trace anomaly and Casimir effect, on the stability of an oscillating universe with respect to decay by tunneling to the singularity. We find that these corrections do not generally stabilize an oscillating universe. However, stability may be achieved for some specially fine-tuned non-vacuum states.
Vibrational resonance in the Morse oscillator
Indian Academy of Sciences (India)
Abstract. The occurrence of vibrational resonance is investigated in both classical and quantum mechanical Morse oscillators driven by a biharmonic force. The biharmonic force consists of two forces of widely different frequencies ω and with. ≫ ω. In the damped and biharmoni- cally driven classical Morse oscillator, ...
Effective harmonic oscillator description of anharmonic molecular ...
Indian Academy of Sciences (India)
... a harmonic oscillator eigenfunction with the centroid and width parameter as variational paraeters. It is found that the effective harmonic oscillator approximation provides a description of the anharmonic eigenstates very similar to the vibrational self consistent field results. Coriolis coupling is also included in these studies.
Neutrino oscillations: Present status and outlook
Indian Academy of Sciences (India)
The status of sterile neutrino oscillation interpretations of the LSND anomaly in the light of recent MiniBooNE results is also discussed. Further-more, an outlook on the measurement of the mixing angle 13 in the near term future, as well as prospects to discover CP violation in neutrino oscillations and to determine the type ...
Effective harmonic oscillator description of anharmonic molecular ...
Indian Academy of Sciences (India)
Administrator
Abstract. The validity of an effective harmonic oscillator approximation for anharmonic molecular vibrations is tested and compared with vibrational self consistent field and vibrational configurational interaction results. The effective harmonic oscillator is constructed variationally, by taking the trial wave function as a harmonic ...
Discontinuous Spirals of Stable Periodic Oscillations
DEFF Research Database (Denmark)
Sack, Achim; Freire, Joana G.; Lindberg, Erik
2013-01-01
We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase...
Energy Technology Data Exchange (ETDEWEB)
Andrade, Fabiano M., E-mail: fmandrade@uepg.br [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900 Ponta Grossa-PR (Brazil); Silva, Edilberto O., E-mail: edilbertoo@gmail.com [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís-MA (Brazil)
2014-11-10
In this Letter, 2D Dirac oscillator in the quantum deformed framework generated by the κ-Poincaré–Hopf algebra is considered. The problem is formulated using the κ-deformed Dirac equation. The resulting theory reveals that the energies and wave functions of the oscillator are modified by the deformation parameter.
In plane oscillation of a bifilar pendulum
Hinrichsen, Peter F.
2016-11-01
The line tensions, the horizontal and vertical accelerations as well as the period of large angle oscillations parallel to the plane of a bifilar suspension are presented and have been experimentally investigated using strain gauges and a smart phone. This system has a number of advantages over the simple pendulum for studying large angle oscillations, and for measuring the acceleration due to gravity.
Oscillating systems with cointegrated phase processes
DEFF Research Database (Denmark)
Østergaard, Jacob; Rahbek, Anders; Ditlevsen, Susanne
2017-01-01
We present cointegration analysis as a method to infer the network structure of a linearly phase coupled oscillating system. By defining a class of oscillating systems with interacting phases, we derive a data generating process where we can specify the coupling structure of a network that resemb...
Neutrino oscillations: Present status and outlook
Indian Academy of Sciences (India)
more, an outlook on the measurement of the mixing angle θ13 in the near term future, as well as prospects to discover CP violation in neutrino oscillations and to determine the type of the neutrino mass ordering by long-baseline experiments in the long term future are given. Keyword. Neutrino oscillations. PACS Nos 14.60.
Small Oscillations via Conservation of Energy
Troy, Tia; Reiner, Megan; Haugen, Andrew J.; Moore, Nathan T.
2017-01-01
The work describes an analogy-based small oscillations analysis of a standard static equilibrium lab problem. In addition to force analysis, a potential energy function for the system is developed, and by drawing out mathematical similarities to the simple harmonic oscillator, we are able to describe (and experimentally verify) the period of small…
Oscillations of first order difference equations
Indian Academy of Sciences (India)
Oscillations of first order difference equations. N PARHI. Department of Mathematics, Berhampur University, Berhampur 760 007, India. MS received 10 June 1999; revised 28 December 1999. Abstract. The oscillatory and asymptotic behaviour of solutions of first order diff- erence equations is studied. Keywords. Oscillation ...
Teaching Oscillations by a Model of Nanoresonator
Lindell, A.; Viiri, J.
2009-01-01
Nanoscience offers fascinating opportunities for science education as it links the achievements of modern technology to traditional models of science. In this article we present a nanotechnology orientated lesson on oscillations, suitable for physics courses at high schools and universities. The focus of the lesson is in forced oscillations on a…
Oscillator clustering in a resource distribution chain
DEFF Research Database (Denmark)
Postnov, D.; Sosnovtseva, Olga; Mosekilde, Erik
2005-01-01
separate the inherent dynamics of the individual oscillator from the properties of the coupling network. Illustrated by examples from microbiological population dynamics, renal physiology, and electronic oscillator theory, we show how competition for primary resources in a resource distribution chain leads...
Modeling diauxic glycolytic oscillations in yeast
DEFF Research Database (Denmark)
Hald, Bjørn Olav; Sørensen, Preben Graae
2010-01-01
Glycolytic oscillations in a stirred suspension of starved yeast cells is an excellent model system for studying the dynamics of metabolic switching in living systems. In an open-flow system the oscillations can be maintained indefinitely at a constant operating point where they can be characteri...
Experimental observation of shear thickening oscillation
DEFF Research Database (Denmark)
Nagahiro, Shin-ichiro; Nakanishi, Hiizu; Mitarai, Namiko
2013-01-01
We report experimental observations of the shear thickening oscillation, i.e. the spontaneous macroscopic oscillation in the shear flow of severe shear thickening fluid. Using a density-matched starch-water mixture, in the cylindrical shear flow of a few centimeters flow width, we observed...
Surface plasmon excitation by a quantum oscillator
Lidsky, V. V.
2009-01-01
Surface waves in a thin uniform metal film are described in terms of quantum electrodynamics.The interaction of surface waves with a quantum oscillator is discussed in the dipole approximation. The increase in the spontaneous emission rate of the excited quantum oscillator, the so called Purcell factor, is evaluated to be as high as by 10 to the five times.
Chemical sensor with oscillating cantilevered probe
Adams, Jesse D
2013-02-05
The invention provides a method of detecting a chemical species with an oscillating cantilevered probe. A cantilevered beam is driven into oscillation with a drive mechanism coupled to the cantilevered beam. A free end of the oscillating cantilevered beam is tapped against a mechanical stop coupled to a base end of the cantilevered beam. An amplitude of the oscillating cantilevered beam is measured with a sense mechanism coupled to the cantilevered beam. A treated portion of the cantilevered beam is exposed to the chemical species, wherein the cantilevered beam bends when exposed to the chemical species. A second amplitude of the oscillating cantilevered beam is measured, and the chemical species is determined based on the measured amplitudes.
New neutrino oscillation results from NOVA
CERN. Geneva
2018-01-01
Neutrinos oscillate among flavors as they travel because a neutrino of a particular flavor is also a superposition of multiple neutrinos with slightly different masses. The interferometric nature of oscillations allows these tiny mass differences to be measured, along with the parameters of the PMNS matrix which governs the mixing. However, since neutrinos only interact weakly, a powerful neutrino source and massive detectors are required to measure them. In this talk I will show recently updated results from NOvA, a long-baseline neutrino oscillation experiment at Fermilab with two functionally identical scintillator detectors. I will present measurements of muon neutrino disappearance and electron neutrino appearance, and what constraints those measurements put on the remaining open questions in neutrino oscillations: Is the neutrino mass hierarchy "normal" or "inverted?" Do neutrino oscillations violate CP symmetry? Is the mixing in the atmospheric sector maximal? The recent update includes 50%...
Is the quadrature oscillator a multivibrator?
DEFF Research Database (Denmark)
Lindberg, Erik
2004-01-01
The aim of this article is to give insight into the mechanisms behind the behavior of oscillators from a new angle, introducing the idea of "frozen eigenvalues". This approach is based on piecewise-linear modelling and a study of the eigenvalues of the time varying linearized Jacobian of the nonl......The aim of this article is to give insight into the mechanisms behind the behavior of oscillators from a new angle, introducing the idea of "frozen eigenvalues". This approach is based on piecewise-linear modelling and a study of the eigenvalues of the time varying linearized Jacobian...... of the nonlinear differential equations describing the oscillator. A multivibrator and a quadrature oscillator are used as test examples. The mechanisms behind the oscillations of the two circuits are compared....
Improved memristor-based relaxation oscillator
Mosad, Ahmed G.
2013-09-01
This paper presents an improved memristor-based relaxation oscillator which offers higher frequency and wider tunning range than the existing reactance-less oscillators. It also has the capability of operating on two positive supplies or alternatively a positive and negative supply. Furthermore, it has the advantage that it can be fully integrated on-chip providing an area-efficient solution. On the other hand, The oscillation concept is discussed then a complete mathematical analysis of the proposed oscillator is introduced. Furthermore, the power consumption of the new relaxation circuit is discussed and validated by the PSPICE circuit simulations showing an excellent agreement. MATLAB results are also introduced to demonstrate the resistance range and the corresponding frequency range which can be obtained from the proposed relaxation oscillator. © 2013 Elsevier Ltd.
Atmospheric neutrino oscillations for earth tomography
Energy Technology Data Exchange (ETDEWEB)
Winter, Walter
2016-04-05
Modern proposed atmospheric neutrino oscillation experiments, such as PINGU in the Antarctic ice or ORCA in Mediterranean sea water, aim for precision measurements of the oscillation parameters including the ordering of the neutrino masses. They can, however, go far beyond that: Since neutrino oscillations are affected by the coherent forward scattering with matter, neutrinos can provide a new view on the interior of the earth. We show that the proposed atmospheric oscillation experiments can measure the lower mantle density of the earth with a precision at the level of a few percent, including the uncertainties of the oscillation parameters and correlations among different density layers. While the earth's core is, in principle, accessible by the angular resolution, new technology would be required to extract degeneracy-free information.
Atmospheric neutrino oscillations for Earth tomography
Energy Technology Data Exchange (ETDEWEB)
Winter, Walter, E-mail: walter.winter@desy.de
2016-07-15
Modern proposed atmospheric neutrino oscillation experiments, such as PINGU in the Antarctic ice or ORCA in Mediterranean sea water, aim for precision measurements of the oscillation parameters including the ordering of the neutrino masses. They can, however, go far beyond that: Since neutrino oscillations are affected by the coherent forward scattering with matter, neutrinos can provide a new view on the interior of the earth. We show that the proposed atmospheric oscillation experiments can measure the lower mantle density of the earth with a precision at the level of a few percent, including the uncertainties of the oscillation parameters and correlations among different density layers. While the earth's core is, in principle, accessible by the angular resolution, new technology would be required to extract degeneracy-free information.
Atmospheric neutrino oscillations for Earth tomography
Winter, Walter
2016-07-01
Modern proposed atmospheric neutrino oscillation experiments, such as PINGU in the Antarctic ice or ORCA in Mediterranean sea water, aim for precision measurements of the oscillation parameters including the ordering of the neutrino masses. They can, however, go far beyond that: Since neutrino oscillations are affected by the coherent forward scattering with matter, neutrinos can provide a new view on the interior of the earth. We show that the proposed atmospheric oscillation experiments can measure the lower mantle density of the earth with a precision at the level of a few percent, including the uncertainties of the oscillation parameters and correlations among different density layers. While the earth's core is, in principle, accessible by the angular resolution, new technology would be required to extract degeneracy-free information.
Geometric phase shifts in biological oscillators.
Tourigny, David S
2014-08-21
Many intracellular processes continue to oscillate during the cell cycle. Although it is not well-understood how they are affected by discontinuities in the cellular environment, the general assumption is that oscillations remain robust provided the period of cell divisions is much larger than the period of the oscillator. Here, I will show that under these conditions a cell will in fact have to correct for an additional quantity added to the phase of oscillation upon every repetition of the cell cycle. The resulting phase shift is an analogue of the geometric phase, a curious entity first discovered in quantum mechanics. In this letter, I will discuss the theory of the geometric phase shift and demonstrate its relevance to biological oscillations. Copyright © 2014 Elsevier Ltd. All rights reserved.
Global dynamics of a stochastic neuronal oscillator
Yamanobe, Takanobu
2013-11-01
Nonlinear oscillators have been used to model neurons that fire periodically in the absence of input. These oscillators, which are called neuronal oscillators, share some common response structures with other biological oscillations such as cardiac cells. In this study, we analyze the dependence of the global dynamics of an impulse-driven stochastic neuronal oscillator on the relaxation rate to the limit cycle, the strength of the intrinsic noise, and the impulsive input parameters. To do this, we use a Markov operator that both reflects the density evolution of the oscillator and is an extension of the phase transition curve, which describes the phase shift due to a single isolated impulse. Previously, we derived the Markov operator for the finite relaxation rate that describes the dynamics of the entire phase plane. Here, we construct a Markov operator for the infinite relaxation rate that describes the stochastic dynamics restricted to the limit cycle. In both cases, the response of the stochastic neuronal oscillator to time-varying impulses is described by a product of Markov operators. Furthermore, we calculate the number of spikes between two consecutive impulses to relate the dynamics of the oscillator to the number of spikes per unit time and the interspike interval density. Specifically, we analyze the dynamics of the number of spikes per unit time based on the properties of the Markov operators. Each Markov operator can be decomposed into stationary and transient components based on the properties of the eigenvalues and eigenfunctions. This allows us to evaluate the difference in the number of spikes per unit time between the stationary and transient responses of the oscillator, which we show to be based on the dependence of the oscillator on past activity. Our analysis shows how the duration of the past neuronal activity depends on the relaxation rate, the noise strength, and the impulsive input parameters.
Oscillations and synchrony in a cortical neural network.
Qu, Jingyi; Wang, Rubin; Yan, Chuankui; Du, Ying
2014-04-01
In this paper, the oscillations and synchronization status of two different network connectivity patterns based on Izhikevich model are studied. One of the connectivity patterns is a randomly connected neuronal network, the other one is a small-world neuronal network. This Izhikevich model is a simple model which can not only reproduce the rich behaviors of biological neurons but also has only two equations and one nonlinear term. Detailed investigations reveal that by varying some key parameters, such as the connection weights of neurons, the external current injection, the noise of intensity and the neuron number, this neuronal network will exhibit various collective behaviors in randomly coupled neuronal network. In addition, we show that by changing the number of nearest neighbor and connection probability in small-world topology can also affect the collective dynamics of neuronal activity. These results may be instructive in understanding the collective dynamics of mammalian cortex.
Locking of correlated neural activity to ongoing oscillations.
Directory of Open Access Journals (Sweden)
Tobias Kühn
2017-06-01
Full Text Available Population-wide oscillations are ubiquitously observed in mesoscopic signals of cortical activity. In these network states a global oscillatory cycle modulates the propensity of neurons to fire. Synchronous activation of neurons has been hypothesized to be a separate channel of signal processing information in the brain. A salient question is therefore if and how oscillations interact with spike synchrony and in how far these channels can be considered separate. Experiments indeed showed that correlated spiking co-modulates with the static firing rate and is also tightly locked to the phase of beta-oscillations. While the dependence of correlations on the mean rate is well understood in feed-forward networks, it remains unclear why and by which mechanisms correlations tightly lock to an oscillatory cycle. We here demonstrate that such correlated activation of pairs of neurons is qualitatively explained by periodically-driven random networks. We identify the mechanisms by which covariances depend on a driving periodic stimulus. Mean-field theory combined with linear response theory yields closed-form expressions for the cyclostationary mean activities and pairwise zero-time-lag covariances of binary recurrent random networks. Two distinct mechanisms cause time-dependent covariances: the modulation of the susceptibility of single neurons (via the external input and network feedback and the time-varying variances of single unit activities. For some parameters, the effectively inhibitory recurrent feedback leads to resonant covariances even if mean activities show non-resonant behavior. Our analytical results open the question of time-modulated synchronous activity to a quantitative analysis.
Periodic motions and resonances of impact oscillators
Dyskin, Arcady V.; Pasternak, Elena; Pelinovsky, Efim
2012-06-01
Bilinear oscillators - the oscillators whose springs have different stiffnesses in compression and tension - model a wide range of phenomena. A limiting case of bilinear oscillator with infinite stiffness in compression - the impact oscillator - is studied here. We investigate a special set of impact times - the eigenset, which corresponds to the solution of the homogeneous equation, i.e. the oscillator without the driving force. We found that this set and its subsets are stable with respect to variation of initial conditions. Furthermore, amongst all periodic sets of impact times with the period commensurate with the period of driving force, the eigenset is the only one which can support resonances, in particular the multi-'harmonic' resonances. Other resonances should produce non-periodic sets of impact times. This funding indicates that the usual simplifying assumption [e.g., S.W. Shaw, P.J. Holmes, A periodically forced piecewise linear oscillator, Journal of Sound and Vibration 90 (1983) 129-155] that the times between impacts are commensurate with the period of the driving force does not always hold. We showed that for the first sub-'harmonic resonance' - the resonance achieved on a half frequency of the main resonance - the set of impact times is asymptotically close to the eigenset. The envelope of the oscillations in this resonance increases as a square root of time, opposite to the linear increase characteristic of multi-'harmonic' resonances.
Gaussian white noise excited elasto-Plastic oscillator of several degrees of freedom
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Randrup-thomsen, Søren
1996-01-01
The Slepian model process method has turned out to be a powerful tool to obtain accurate approximations to the long run probability distributions of the plastic displacements of a one degree of freedom linear elastic-ideal plastic oscillator (EPO) subject to stationary Gaussian white noise...... this restriction the obtained Slepian model results fit well with the results obtained by direct response simulations. Also it is observed that the restriction gets less importance for decreasing intensity of the white noise excitation. Keywords: Random vibrations, Slepian models, MDOF elasto-plastic oscillator...
Noise-induced quasi-periodic oscillations in Hindmarsh-Rose neuron model
Ryashko, Lev; Slepukhina, Evdokia
2017-09-01
We study the phenomenon of noise-induced quasi-periodic oscillations in the stochastic Hindmarsh-Rose neuron model. We show that with the increase of the noise intensity the quiescent regime in this model transforms into the quasi-periodic (bursting) one with the formation of the stochastic torus. This phenomenon is confirmed by changes in the probability distribution of random trajectories and by the interspike intervals statistics. We show that the emergence of the torus bursting oscillations is related to the peculiarities of the geometrical arrangement of deterministic trajectories near the equilibrium and its stochastic sensitivity.
Bai, Li; Huang, Xiaoying; Yang, Qian; Wu, Jian-young
2015-01-01
We have discovered an evoked network oscillation in rat neocortical slices and have examined its spatiotemporal patterns with voltage sensitive dye imaging. The slices (visual and auditory cortices) were prepared in a medium of low calcium, high magnesium and with sodium replaced by choline in order to reduce the excito-toxicity and sodium loading. After slicing, the choline was washed out while normal calcium, magnesium and sodium concentrations were restored. The oscillation was evoked by a single electrical shock to slices bathed in normal artificial cerebral spinal fluid (ACSF). The oscillation was organized as an all-or-none epoch containing 4 to 13 cycles at a central frequency around 25 Hz. The activity can be reversibly blocked by CNQX, APV and atropine, but not by bicuculline, indicating poly-synaptic excitatory mechanisms. Voltage sensitive dye imaging showed high amplitude oscillation signals in superficial and middle cortical layers. Spatiotemporally, the oscillations were organized as waves, propagating horizontally along cortical laminar. Each oscillation cycle was associated with one wave propagating in space. The waveforms were often different at different locations (e.g., extra cycles), suggesting the co-existence of multiple local oscillators. For different cycles, the waves often initiated at different locations, suggesting that local oscillators are competing to initiate each oscillation cycle. Overall our results suggest that this cortical network oscillation is organized at two levels: locally, oscillating neurons are tightly coupled to form local oscillators, and globally the coupling between local oscillators is weak, allowing abrupt spatial phase lags and propagating waves with multiple initiation sites. PMID:16870836
Oscillating and rotating sine-Gordon system
DEFF Research Database (Denmark)
Olsen, O. H.; Samuelsen, Mogens Rugholm
1986-01-01
The interaction between a 2π kink and the background or vacuum is investigated in the pure sine-Gordon system. For an oscillating background (i.e., the k=0 part of the phonon spectrum) the 2π kink oscillates, while for increasing or decreasing vacuum two phenomena have been observed, depending...... on the rate of change of the vacuum. For small rates a parametric excitation of standing waves is found, and for larger rates the system linearizes. In the case of oscillating vacuum a perturbation approach explains the behavior perfectly, while for small rates of increasing vacuum the system reduces...
Oscillators - an approach for a better understanding
DEFF Research Database (Denmark)
Lindberg, Erik
2003-01-01
The aim of this tutorial is to provide an electronic engineer knowledge and insight for a better understanding of the mechanisms behind the behaviour of electronic oscillators. A linear oscillator is a mathematical fiction which can only be used as a starting point for the design of a real...... oscillator based on the Barkhausen criteria. Statements in textbooks and papers saying that the nonlinearities are bringing back the poles to the imaginary axis are wrong. The concept of "frozen eigenvalues" is introduced by means of piece-wise-linear modelling of the nonlinear components which are necessary...
Phase Multistability in Coupled Oscillator Systems
DEFF Research Database (Denmark)
Mosekilde, Erik; Postnov, D.E.; Sosnovtseva, Olga
2003-01-01
The phenomenon of phase multistability arises in connection with the synchronization of coupled oscillator systems when the systems individually display complex wave forms associated, for instance, with the presence of subharmonic components or with significant variations of the phase velocity...... along the orbit of the individual oscillator. Focusing on the mechanisms underlying the appearance of phase multistability, the paper examines a variety of phase-locked patterns. In particular we demonstrate the nested structure of synchronization regions for oscillations with multicrest wave forms...... and investigate how the number of spikes per train and the proximity of a neighboring equilibrium point can influence the formation of coexisting regimes in coupled bursters....
Possible solar modulation of pacific decadal oscillation
Ma, Lihua; Yin, Zhiqiang
2017-09-01
The Pacific Decadal Oscillation (PDO) is an El Niño-like pattern of Pacific climate variability, oscillating between its warm and cool phase about every 20-30 years as defined by oceanic temperature anomalies in the northeast and tropical Pacific Ocean. In this work, the authors investigate the possible connection between the PDO and solar activity by means of wavelet technique. The study shows obvious fluctuation characteristics in the PDO series. The modulation action from solar activity plays an important role in the oscillation of the Pacific, and there is a possible association existing in the PDO and solar activity on decade time scales.
Relativistic quantum mechanics of a Dirac oscillator
Martines y Romero, R P; Salas-Brito, A L
1995-01-01
The Dirac oscillator is an exactly soluble model recently introduced in the context of many particle models in relativistic quantum mechanics. The model has been also considered as an interaction term for modelling quark confinement in quantum chromodynamics. These considerations should be enough for demonstrating that the Dirac oscillator can be an excellent example in relativistic quantum mechanics. In this paper we offer a solution to the problem and discuss some of its properties. We also discuss a physical picture for the Dirac oscillator's non-standard interaction, showing how it arises on describing the behaviour of a neutral particle carrying an anomalous magnetic moment and moving inside a uniformly charged sphere. (author)
Damping of Crank–Nicolson error oscillations
DEFF Research Database (Denmark)
Britz, Dieter; Østerby, Ole; Strutwolf, J.
2003-01-01
The Crank–Nicolson (CN) simulation method has an oscillatory response to sharp initial transients. The technique is convenient but the oscillations make it less popular. Several ways of damping the oscillations in two types of electrochemical computations are investigated. For a simple one...... be computationally more expensive with some systems. The simple device of starting with one backward implicit (BI, or Laasonen) step does damp the oscillations, but not always sufficiently. For electrochemical microdisk simulations which are two-dimensional in space and using CN, the use of a first BI step is much...
Oscillating magnetocaloric effect of a multilayer graphene
Energy Technology Data Exchange (ETDEWEB)
Alisultanov, Z. Z., E-mail: zaur0102@gmail.com [Amirkhanov Institute of Physics, Russian Academy of Sciences, Dagestan Science Centre, Makhachkala (Russian Federation); Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Dagestan State University, Makhachkala (Russian Federation); Paixão, L. S.; Reis, M. S. [Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, 24210-346 Niterói, RJ (Brazil)
2014-12-08
The oscillating magnetocaloric effect of a multilayer graphene in Bernal and rhombohedral stacking is investigated to extend the previous knowledge of the effect on a single layer graphene. We started from results of a tight-binding model and obtained analytical expressions for the thermodynamic potential and for the entropy change. The last exhibits the same dependence on field and temperature observed for other diamagnetic systems; it oscillates with the inverse magnetic field and presents a maximum value at a given temperature. The amplitude of the oscillating entropy change decreases with the number of layers and the stacking sequence rules the magnetocaloric properties of the system.
Oscillating magnetocaloric effect of a multilayer graphene
Alisultanov, Z. Z.; Paixão, L. S.; Reis, M. S.
2014-12-01
The oscillating magnetocaloric effect of a multilayer graphene in Bernal and rhombohedral stacking is investigated to extend the previous knowledge of the effect on a single layer graphene. We started from results of a tight-binding model and obtained analytical expressions for the thermodynamic potential and for the entropy change. The last exhibits the same dependence on field and temperature observed for other diamagnetic systems; it oscillates with the inverse magnetic field and presents a maximum value at a given temperature. The amplitude of the oscillating entropy change decreases with the number of layers and the stacking sequence rules the magnetocaloric properties of the system.
Compact heterodyne NEMS oscillator for sensing applications
Sansa, Marc; Gourlat, Guillaume; Jourdan, Guillaume; Gely, Marc; Villard, Patrick; Sicard, Gilles; Hentz, Sébastien
2016-11-01
We present a novel topology of heterodyne nanoelectromechanical self-oscillator, aimed at the dense integration of resonator arrays for sensing applications. This oscillator is based on an original measurement method, suitable for both open loop and closed loop operations, which simplifies current down-mixing set-ups. When implemented on-chip, it will allow the reduction of the size and power consumption of readout CMOS circuitry. This is today the limiting factor for the integration density of NEMS oscillators for real-life applications. Here we characterize this method in both open-loop and closed-loop, and evaluate its frequency stability.
Oscillations in glycolysis in Saccharomyces cerevisiae
DEFF Research Database (Denmark)
Kloster, Antonina; Olsen, Lars Folke
2012-01-01
also decreases by stimulating the ATPase activity, e.g. by FCCP or Amphotericin B. Thus, ATPase activity strongly affects the glycolytic oscillations. We discuss these data in relation to a simple autocatalytic model of glycolysis which can reproduce the experimental data and explain the role...... of membrane-bound ATPases . In addition we also studied a recent detailed model of glycolysis and found that, although thismodel faithfully reproduces the oscillations of glycolytic intermediates observed experimentally, it is not able to explain the role of ATPase activity on the oscillations....
Polaritonic Rabi and Josephson Oscillations.
Rahmani, Amir; Laussy, Fabrice P
2016-07-25
The dynamics of coupled condensates is a wide-encompassing problem with relevance to superconductors, BECs in traps, superfluids, etc. Here, we provide a unified picture of this fundamental problem that includes i) detuning of the free energies, ii) different self-interaction strengths and iii) finite lifetime of the modes. At such, this is particularly relevant for the dynamics of polaritons, both for their internal dynamics between their light and matter constituents, as well as for the more conventional dynamics of two spatially separated condensates. Polaritons are short-lived, interact only through their material fraction and are easily detuned. At such, they bring several variations to their atomic counterpart. We show that the combination of these parameters results in important twists to the phenomenology of the Josephson effect, such as the behaviour of the relative phase (running or oscillating) or the occurence of self-trapping. We undertake a comprehensive stability analysis of the fixed points on a normalized Bloch sphere, that allows us to provide a generalized criterion to identify the Rabi and Josephson regimes in presence of detuning and decay.
Torsional oscillations of strange stars
Directory of Open Access Journals (Sweden)
Mannarelli Massimo
2014-01-01
Full Text Available Strange stars are one of the hypothetical compact stellar objects that can be formed after a supernova explosion. The existence of these objects relies on the absolute stability of strange collapsed quark matter with respect to standard nuclear matter. We discuss simple models of strange stars with a bare quark matter surface, thus standard nuclear matter is completely absent. In these models an electric dipole layer a few hundreds Fermi thick should exist close to the star surface. Studying the torsional oscillations of the electrically charged layer we estimate the emitted power, finding that it is of the order of 1045 erg/s, meaning that these objects would be among the brightest compact sources in the heavens. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. Although part of the radiated power should be absorbed by the electrosphere surrounding the strange star, a sizable fraction of photons should escape and be detectable.
Recherche des oscillations de Neutrinos $\
Gangler, E
1997-01-01
Le detecteur nomad, place sur le faisceau de neutrinos wide-band-beam du sps, de contamination en neutrino tau marginale, permet de rechercher des oscillations neutrino muon - tau dans la region de pertinence cosmologique et de distinguer statistiquement les courants charges des neutrinos tau essentiellement par leur mesure cinematique. Une large part du travail de these a donc ete consacree a la reconstruction des evenements dans les chambres a derive, cible instrumentee et cur de l'experience, dont la physique de detection est decrite. Une methode de recherche de traces fut developpee, utilisant certaines informations d'un autre sous-detecteur de nomad, le trd. Pour combler une perte d'efficacite de reconstruction, une methode de recherche de traces courtes s'appuyant sur des vertex deja constitues fut developpee en exploitant les potentialites du filtre de kalman, algorithme iteratif d'ajustement de traces. Ces methodes sont utilisees en production par la collaboration. Cette these porte sur la recherche d...
Oscillation characteristics of zero-field spin transfer oscillators with field-like torque
Energy Technology Data Exchange (ETDEWEB)
Guo, Yuan-Yuan; Xue, Hai-Bin, E-mail: xuehaibin@tyut.edu.cn [Key Laboratory of Advanced Transducer and Intelligent Control system, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Zhe-Jie, E-mail: pandanlzj@hotmail.com [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)
2015-05-15
We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs) consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators.
Oscillation characteristics of zero-field spin transfer oscillators with field-like torque
Directory of Open Access Journals (Sweden)
Yuan-Yuan Guo
2015-05-01
Full Text Available We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators.
Rayleigh-type parametric chemical oscillation.
Ghosh, Shyamolina; Ray, Deb Shankar
2015-09-28
We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.
Searching for Global oscillations of Jupiter
Murphy, N.; Smith, E. J.; Rogers, W.; Gillam, S.; Rosner, R.; Baliunas, S.
2000-12-01
The detection of global oscillations of Jupiter would lead to significant advances in our understanding of giant planet internal structure, analogous to the enormous increase in knowledge of the sun's interior facilitated by helioseismology. In particular, the frequencies of p-mode oscillations will be strongly affected by the presence of density discontinuities and the planet's core size and structure. While it is clear from previous observations that such oscillations probably only exist with very small amplitudes, current instrumentation may still be able to detect them. We will describe a proposed experiment to detect (or place a firm upper amplitude limit on) global p-mode oscillations of Jupiter, using a magneto-optical filter on the Mt Wilson 100" telescope. We will describe the operation of the instrument, present preliminary data and describe models of instrument response which show that with 7 nights of data we can expect to detect signals with amplitudes less than 20 cm/s.
Star-shaped oscillations of Leidenfrost drops
Ma, Xiaolei; Liétor-Santos, Juan-José; Burton, Justin C.
2017-03-01
We experimentally investigate the self-sustained, star-shaped oscillations of Leidenfrost drops. The drops levitate on a cushion of evaporated vapor over a heated, curved surface. We observe modes with n =2 -13 lobes around the drop periphery. We find that the wavelength of the oscillations depends only on the capillary length of the liquid and is independent of the drop radius and substrate temperature. However, the number of observed modes depends sensitively on the liquid viscosity. The dominant frequency of pressure variations in the vapor layer is approximately twice the drop oscillation frequency, consistent with a parametric forcing mechanism. Our results show that the star-shaped oscillations are driven by capillary waves of a characteristic wavelength beneath the drop and that the waves are generated by a large shear stress at the liquid-vapor interface.
Dynamical evolution of quantum oscillators toward equilibrium.
Usha Devi, A R; Rajagopal, A K
2009-07-01
A pure quantum state of large number N of oscillators, interacting via harmonic coupling, evolves such that any small subsystem n
Generalized decomposition methods for singular oscillators
Energy Technology Data Exchange (ETDEWEB)
Ramos, J.I. [Room I-320-D, E. T. S. Ingenieros Industriales, Universidad de Malaga, Plaza El Ejido, s/n 29013 Malaga (Spain)], E-mail: jirs@lcc.uma.es
2009-10-30
Generalized decomposition methods based on a Volterra integral equation, the introduction of an ordering parameter and a power series expansion of the solution in terms of the ordering parameter are developed and used to determine the solution and the frequency of oscillation of a singular, nonlinear oscillator with an odd nonlinearity. It is shown that these techniques provide solutions which are free from secularities if the unknown frequency of oscillation is also expanded in power series of the ordering parameter, require that the nonlinearities be analytic functions of their arguments, and, at leading-order, provide the same frequency of oscillation as two-level iterative techniques, the homotopy perturbation method if the constants that appear in the governing equation are expanded in power series of the ordering parameter, and modified artificial parameter - Linstedt-Poincare procedures.
Monolithic, Widely Tunable, THz Local Oscillator Project
National Aeronautics and Space Administration — This proposal describes development of a new type of quantum-cascade laser for use as a local oscillator at frequencies above 2 THz. The THz source described is a...
Another look at synchronized neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Akhmedov, Evgeny, E-mail: akhmedov@mpi-hd.mpg.de [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Mirizzi, Alessandro, E-mail: alessandro.mirizzi@ba.infn.it [Dipartimento Interateneo di Fisica “Michelangelo Merlin”, Via Amendola 173, 70126 Bari (Italy); Istituto Nazionale di Fisica Nucleare - Sezione di Bari, Via Amendola 173, 70126 Bari (Italy)
2016-07-15
In dense neutrino backgrounds present in supernovae and in the early Universe neutrino oscillations may exhibit complex collective phenomena, such as synchronized oscillations, bipolar oscillations and spectral splits and swaps. We consider in detail possible decoherence effects on the simplest of these phenomena – synchronized neutrino oscillations that can occur in a uniform and isotropic neutrino gas. We develop an exact formalism of spectral moments of the flavour spin vectors describing such a system and then apply it to find analytical approaches that allow one to study decoherence effects on its late-time evolution. This turns out to be possible in part due to the existence of the (previously unknown) exact conservation law satisfied by the quantities describing the considered neutrino system. Interpretation of the decoherence effects in terms of neutrino wave packet separation is also given, both in the adiabatic and non-adiabatic regimes of neutrino flavour evolution.
On the κ-Dirac oscillator revisited
Energy Technology Data Exchange (ETDEWEB)
Andrade, F.M., E-mail: fmandrade@uepg.br [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900 Ponta Grossa, PR (Brazil); Silva, E.O., E-mail: edilbertoos@pq.cnpq.br [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís, MA (Brazil); Ferreira, M.M., E-mail: manojr.ufma@gmail.com [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís, MA (Brazil); Rodrigues, E.C., E-mail: ednilson.fisica@gmail.com [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís, MA (Brazil)
2014-04-04
This Letter is based on the κ-Dirac equation, derived from the κ-Poincaré–Hopf algebra. It is shown that the κ-Dirac equation preserves parity while breaks charge conjugation and time reversal symmetries. Introducing the Dirac oscillator prescription, p→p−imωβr, in the κ-Dirac equation, one obtains the κ-Dirac oscillator. Using a decomposition in terms of spin angular functions, one achieves the deformed radial equations, with the associated deformed energy eigenvalues and eigenfunctions. The deformation parameter breaks the infinite degeneracy of the Dirac oscillator. In the case where ε=0, one recovers the energy eigenvalues and eigenfunctions of the Dirac oscillator.
Large quantum dots with small oscillator strength
DEFF Research Database (Denmark)
Stobbe, Søren; Schlereth, T.W.; Höfling, S.
2010-01-01
We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots...... is measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large...... oscillator strength due to Coulomb effects. This is in stark contrast to the measured oscillator strength, which turns out to be so small that it can be described by excitons in the strong confinement regime. We attribute these findings to exciton localization in local potential minima arising from alloy...
Sustained oscillations for density dependent Markov processes.
Baxendale, Peter H; Greenwood, Priscilla E
2011-09-01
Simulations of models of epidemics, biochemical systems, and other bio-systems show that when deterministic models yield damped oscillations, stochastic counterparts show sustained oscillations at an amplitude well above the expected noise level. A characterization of damped oscillations in terms of the local linear structure of the associated dynamics is well known, but in general there remains the problem of identifying the stochastic process which is observed in stochastic simulations. Here we show that in a general limiting sense the stochastic path describes a circular motion modulated by a slowly varying Ornstein-Uhlenbeck process. Numerical examples are shown for the Volterra predator-prey model, Sel'kov's model for glycolysis, and a damped linear oscillator. © Springer-Verlag 2010
Adaptive elimination of synchronization in coupled oscillator
Zhou, Shijie; Ji, Peng; Zhou, Qing; Feng, Jianfeng; Kurths, Jürgen; Lin, Wei
2017-08-01
We present here an adaptive control scheme with a feedback delay to achieve elimination of synchronization in a large population of coupled and synchronized oscillators. We validate the feasibility of this scheme not only in the coupled Kuramoto’s oscillators with a unimodal or bimodal distribution of natural frequency, but also in two representative models of neuronal networks, namely, the FitzHugh-Nagumo spiking oscillators and the Hindmarsh-Rose bursting oscillators. More significantly, we analytically illustrate the feasibility of the proposed scheme with a feedback delay and reveal how the exact topological form of the bimodal natural frequency distribution influences the scheme performance. We anticipate that our developed scheme will deepen the understanding and refinement of those controllers, e.g. techniques of deep brain stimulation, which have been implemented in remedying some synchronization-induced mental disorders including Parkinson disease and epilepsy.
On the Design of Chaotic Oscillators
DEFF Research Database (Denmark)
Lindberg, Erik; Tamasevicius, A; Cenys, A.
1998-01-01
A discussion of the chaotic oscillator concept from a design methodology pointof view. The attributes of some chaoticoscillators are discussed and a systematicdesign method based on eigenvalue investigation is proposed. The method isillustrated with a chaotic Wien-bridgeoscillator design....
Oscillation theory for second order dynamic equations
Agarwal, Ravi P; O''Regan, Donal
2003-01-01
The qualitative theory of dynamic equations is a rapidly developing area of research. In the last 50 years, the Oscillation Theory of ordinary, functional, neutral, partial and impulsive differential equations, and their discrete versions, has inspired many scholars. Hundreds of research papers have been published in every major mathematical journal. Many books deal exclusively with the oscillation of solutions of differential equations, but most of these books appeal only to researchers who already know the subject. In an effort to bring Oscillation Theory to a new and broader audience, the authors present a compact, but thorough, understanding of Oscillation Theory for second order differential equations. They include several examples throughout the text not only to illustrate the theory, but also to provide new direction.
Climate Prediction Center Southern Oscillation Index
National Oceanic and Atmospheric Administration, Department of Commerce — This is one of the CPC?s Monthly Atmospheric and Sea Surface Temperature (SST)Indices. It contains Southern Oscillation Index which is standardized sea level...
Solar oscillations instrumentation and measurement theory
Appourchaux, T.
1988-01-01
Solar-oscillation instruments are reviewed. Common characteristics include detecting solar radial velocities on Fraunhofer lines with a 2-point measuring technique, high spectral resolution and stability, etc. The choice of the spectral line for getting a high signal to solar noise ratio is addressed. Velocity imaging of solar oscillations modes is detailed, including spatial sampling and span, highest observable degree. Applications of these different analyses is applied to existing or future helioseismology instruments.
Experiments with elasto-plastic oscillator
DEFF Research Database (Denmark)
Randrup-thomsen, Søren; Ditlevsen, Ove Dalager
1996-01-01
Plastic displacements of a Gaussian white noise excited three degrees of freedom non-ideal elasto-plastic oscillator are measured in laboratory experiments and the plastic displacements are compared to computer simulated results for the corresponding ideal elasto-plastic oscillator. The comparative...... analysis leads to an equivalent ideal plastic yield limit that gives good coincidence between the simulated distributions and the experimentally determined distributions....
Oscillator Phase Noise: A Geometrical Approach
DEFF Research Database (Denmark)
Djurhuus, Torsten; Krozer, Viktor; Vidkjær, Jens
2009-01-01
We construct a coordinate-independent description of oscillator linear response through a decomposition scheme derived independently of any Floquet theoretic results. Trading matrix algebra for a simpler graphical methodology, the text will present the reader with an opportunity to gain an intuit...... an intuitive understanding of the well-known phase noise macromodel. The topics discussed in this paper include the following: orthogonal decompositions, AM–PM conversion, and nonhyperbolic oscillator noise response....
Harmonic Oscillator SUSY Partners and Evolution Loops
Directory of Open Access Journals (Sweden)
David J. Fernández
2012-07-01
Full Text Available Supersymmetric quantum mechanics is a powerful tool for generating exactly solvable potentials departing from a given initial one. If applied to the harmonic oscillator, a family of Hamiltonians ruled by polynomial Heisenberg algebras is obtained. In this paper it will be shown that the SUSY partner Hamiltonians of the harmonic oscillator can produce evolution loops. The corresponding geometric phases will be as well studied.
Taking a peek at Bloch oscillations
Morsch, Oliver
2016-11-01
Bloch oscillations arise when matter waves inside a periodic potential, such as a crystal lattice, are accelerated by a constant force. Keßler et al (2016 New J. Phys. 18 102001) have now experimentally tested a method that allows one to observe those oscillations continuously, without a destructive measurement on the matter wave. Their approach could help to make cold atom-based accelerometers and gravimeters more precise.
Broadband hyperchaotic oscillator with delay line
DEFF Research Database (Denmark)
Cenys, Antanas; Lindberg, Erik; Anagnostopoulos, A. N.
2002-01-01
Dynamical systems with time delay can be employed as high dimensional hyperchaotic oscillators with multiple positive Lyapunov exponents. We describe an electronic circuit composed of a 3-stage amplifier and a delay line in the feedback loop. The 1st stage of the amplifier is a nonlinear one whil...... 20 dB. Mathematical models are presented. The oscillators are described either by a scalar nonlinear DDE or by a set combined of one nonlinear DDE and two linear ODEs....
Dynamics-Enabled Nanoelectromechanical Systems (NEMS) Oscillators
2014-06-01
AFRL-RY-WP-TR-2014-0144 DYNAMICS-ENABLED NANOELECTROMECHANICAL SYSTEMS ( NEMS ) OSCILLATORS Michael Roukes California Institute...SYSTEMS ( NEMS ) OSCILLATORS 5a. CONTRACT NUMBER FA8650-10-1-7029 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61101E 6. AUTHOR(S) Michael Roukes...engineer, and demonstrate nonlinear-dynamics-enabled nanoelectromechanical system ( NEMS ) frequency-source technology. 15. SUBJECT TERMS
Autonomous Duffing-Holmes Type Chaotic Oscillator
DEFF Research Database (Denmark)
Tamaševičius, A.; Bumelienė, S.; Kirvaitis, R.
2009-01-01
We have designed and built a novel Duffing type autonomous 3rd-order chaotic oscillator. In comparison with the common non-autonomous DuffingHolmes type oscillator the autonomous circuit has an internal positive feedback loop instead of an external periodic drive source. In addition......, it is supplemented with an RC inertial damping loop providing negative feedback. The circuit has been investigated both numerically and experimentally....
Oscillating electrical motors, application and theory
Energy Technology Data Exchange (ETDEWEB)
Kudarauskas, S. [Klaipeda University, Department of Electrical Engineering, Klaipeda (Lithuania)
2000-08-01
The article analyses classification of electrical machines by the temporal and spatial properties of mechanical movement. It is purposive to group the machines by movement temporal properties thus marking out an independent class of oscillating machines. The article demonstrates operation principles, design diversity and practical utilisation of these machines. Principles of theoretical analysis of main regime (i.e. steady oscillations) are presented. The appendix presents rationale of analogy between electrical circuit and magnetic circuit from energy standpoint. (orig.)
Pseudoclassical description of the Dirac Oscillator
Delsolmesa, Antonio; Martinezyromero, R. P.
1995-01-01
In this paper we discuss the Dirac Oscillator wave equation in terms of pseudoclassical language, using Grassmann variables to describe the internal degrees of freedom of the oscillator. Regarding the original wave equation as a classical constraint, we use the theory of constrained systems, to develop a reparameterization invariant lagrangian, which is the pseudoclassical equivalent of the quantum case. The consistency of the Hamiltonian formalism and the quantization procedure are also analyzed.
Experiments with elasto-plastic oscillator
DEFF Research Database (Denmark)
Randrup-Thomsen, S.; Ditlevsen, Ove Dalager
1999-01-01
Plastic displacements of a Gaussian white noise excited three degrees of freedom non-ideal elasto-plastic oscillator are measured in laboratory experiments and the plastic displacements are compared to computer simulated results for the corresponding ideal elasto-plastic oscillator. The comparative...... analysis leads to an equivalent ideal plastic yield limit that gives good coincidence between the simulated distributions and the experimentally determined distributions. (C) 1998 Published by Elsevier Science Ltd. All rights reserved....
Synchronization of multi-phase oscillators: an Axelrod-inspired model
Kuperman, M. N.; Zanette, D. H.
2009-07-01
Inspired by Axelrod’s model of culture dissemination, we introduce and analyze a model for a population of coupled oscillators where different levels of synchronization can be assimilated to different degrees of cultural organization. The state of each oscillator is represented by a set of phases, and the interaction - which occurs between homologous phases - is weighted by a decreasing function of the distance between individual states. Both ordered arrays and random networks are considered. We find that the transition between synchronization and incoherent behaviour is mediated by a clustering regime with rich organizational structure, where any two oscillators can be synchronized in some of their phases, while their remain unsynchronized in the others.
Mechanical oscillations in lasing microspheres
Toncelli, A.; Capuj, N. E.; Garrido, B.; Sledzinska, M.; Sotomayor-Torres, C. M.; Tredicucci, A.; Navarro-Urrios, D.
2017-08-01
We investigate the feasibility of activating coherent mechanical oscillations in lasing microspheres by modulating the laser emission at a mechanical eigenfrequency. To this aim, 1.5%Nd3+:Barium-Titanium-Silicate microspheres with diameters around 50 μm were used as high quality factor (Q > 106) whispering gallery mode lasing cavities. We have implemented a pump-and-probe technique in which the pump laser used to excite the Nd3+ ions is focused on a single microsphere with a microscope objective and a probe laser excites a specific optical mode with the evanescent field of a tapered fibre. The studied microspheres show monomode and multi-mode lasing action, which can be modulated in the best case up to 10 MHz. We have optically transduced thermally activated mechanical eigenmodes appearing in the 50-70 MHz range, the frequency of which decreases with increasing the size of the microspheres. In a pump-and-probe configuration, we observed modulation of the probe signal up to the maximum pump modulation frequency of our experimental setup, i.e., 20 MHz. This modulation decreases with frequency and is unrelated to lasing emission, pump scattering, or thermal effects. We associate this effect to free-carrier-dispersion induced by multiphoton pump light absorption. On the other hand, we conclude that, in our current experimental conditions, it was not possible to resonantly excite the mechanical modes. Finally, we discuss on how to overcome these limitations by increasing the modulation frequency of the lasing emission and decreasing the frequency of the mechanical eigenmodes displaying a strong degree of optomechanical coupling.
A compact low-power oscillation circuit for the high performance silicon oscillating accelerometer
Zhang, Jiashi; Qiu, Anping; Shi, Qin; Xia, Guoming; Zhao, Yang
2017-10-01
This paper describes a compact and low-power oscillating circuit for silicon oscillating accelerometer (SOA). The influence of oscillation amplitude control strategy on accelerometer performance is analyzed. A rail to rail comparator replaces the traditional AGC (automatic gain control) circuit for oscillation amplitude control. It makes the circuit more compact, lower power consumption, and reduces the flicker noise introduced by amplitude control greatly. The experiment shows the bias stability is 13.3µg from 22.9µg, the bias-instability is 4.3µg from 9.3µg, and the system power consumption is reduced to 200mW from 1.2W.
MEDIA PEMBELAJARAN ANALOG OSCILLATOR VIRTUAL LABOLATORY
Directory of Open Access Journals (Sweden)
Aji Widhi Wibowo
2016-01-01
Full Text Available The purpose of this research is to design and implement a Virtual Labolatory Materials Signal Processing Sub discussion 'Oscillator' Analog as Newspapers. Developers using the model Sutopo Ariesto Hadi (2003 as a method to produce the product. Consists of six stages: concept, design, material collecting, assembly, testing and distribution. This results in the development of Virtual media Labolatory with material 'Oscillator' with the results of 4 (four practicum digital oscillator, namely (1 Oscillator Wien Bridge, (2 Colpitts oscillator, (3 Oscillator Hartley and (4 astable multivibrator. Another result is that a user be jobsheet practicum. There are two types, namely: (1 jobsheet grip lecturers and (2 jobsheet for students. In Jobsheet there is a short book that contains the Manual on procedures for the use of virtual labolatory when practical and anatomical description of the product. Virtual Labolatory consists of the initial page (flash scren, the main page (home, pages and pages about the developer's lab referring to the story board. There are four (4 test are: (1 the truth polarity capacitor, (2 the connection (wiring, (3 mode frequency and time in the meter frequency
Mathematical Modeling of an Oscillating Droplet
Berry, S.; Hyers, R. W.; Racz, L. M.; Abedian, B.; Rose, M. Franklin (Technical Monitor)
2000-01-01
Oscillating droplets are of interest in a number of disciplines. A practical application is the oscillating drop method, which is a technique for measuring surface tension and viscosity of liquid metals. It is especially suited to undercooled and highly reactive metals, because it is performed by electromagnetic levitation. The natural oscillation frequency of the droplets is related to the surface tension of the material, and the decay of oscillations is related to its viscosity. The fluid flow inside the droplet must be laminar in order for this technique to yield good results. Because no experimental method has yet been developed to visualize flow in electromagnetically-levitated oscillating metal droplets, mathematical modeling is required to determine whether or not turbulence occurs. Three mathematical models of the flow: (1) assuming laminar conditions, (2) using the k-epsilon turbulence model, and (3) using the RNG turbulence model, respectively, are compared and contrasted to determine the physical characteristics of the flow. It is concluded that the RNG model is the best suited for describing this problem. The goal of the presented work was to characterize internal flow in an oscillating droplet of liquid metal, and to verify the accuracy of the characterization by comparing calculated surface tension and viscosity.
Suppression of oscillations in mean-field diffusion
Indian Academy of Sciences (India)
2015-01-28
Jan 28, 2015 ... We study the role of mean-field diffusive coupling on suppression of oscillations for systems of limit cycle oscillators. We show that this coupling scheme not only induces amplitude death (AD) but also oscillation death (OD) in coupled identical systems. The suppression of oscillations in the parameter space ...
Phillips, Nick E; Manning, Cerys; Papalopulu, Nancy; Rattray, Magnus
2017-05-01
Multiple biological processes are driven by oscillatory gene expression at different time scales. Pulsatile dynamics are thought to be widespread, and single-cell live imaging of gene expression has lead to a surge of dynamic, possibly oscillatory, data for different gene networks. However, the regulation of gene expression at the level of an individual cell involves reactions between finite numbers of molecules, and this can result in inherent randomness in expression dynamics, which blurs the boundaries between aperiodic fluctuations and noisy oscillators. This underlies a new challenge to the experimentalist because neither intuition nor pre-existing methods work well for identifying oscillatory activity in noisy biological time series. Thus, there is an acute need for an objective statistical method for classifying whether an experimentally derived noisy time series is periodic. Here, we present a new data analysis method that combines mechanistic stochastic modelling with the powerful methods of non-parametric regression with Gaussian processes. Our method can distinguish oscillatory gene expression from random fluctuations of non-oscillatory expression in single-cell time series, despite peak-to-peak variability in period and amplitude of single-cell oscillations. We show that our method outperforms the Lomb-Scargle periodogram in successfully classifying cells as oscillatory or non-oscillatory in data simulated from a simple genetic oscillator model and in experimental data. Analysis of bioluminescent live-cell imaging shows a significantly greater number of oscillatory cells when luciferase is driven by a Hes1 promoter (10/19), which has previously been reported to oscillate, than the constitutive MoMuLV 5' LTR (MMLV) promoter (0/25). The method can be applied to data from any gene network to both quantify the proportion of oscillating cells within a population and to measure the period and quality of oscillations. It is publicly available as a MATLAB
Memristor-based relaxation oscillators using digital gates
Khatib, Moustafa A.
2012-11-01
This paper presents two memristor-based relaxation oscillators. The proposed oscillators are designed without the need of any reactive elements, i.e., capacitor or inductor. As the \\'resistance storage\\' property of the memristor can be exploited to generate the oscillation. The proposed oscillators have the advantage that they can be fully integrated on-chip giving an area-efficient solution. Furthermore, these oscillators give higher frequency other than the existing reactance-less oscillator and provide a wider range of the resistance. The concept of operation and the mathematical analysis for the proposed oscillators are explained and verified with circuit simulations showing an excellent agreement. © 2012 IEEE.
Four-Phase Oscillators Employing Two Active Elements
Directory of Open Access Journals (Sweden)
V. Biolkova
2011-04-01
Full Text Available Two novel four-phase voltage-output oscillators are proposed. These circuits can also be utilized as quadrature oscillators with floating outputs. Each oscillator employs two DO-CIBA (Differential Output- Current Inverter Buffered Amplifier, two grounded capacitors, and four or three resistors. Independent control of the oscillation frequency (OF and oscillation condition is practicable in both oscillators. Real measurements on the oscillator specimens confirm the ability of easy OF control and extra low THD, which is less than 0.07%.
Slepian Simulations of Plastic Displacements of Randomly Excited Hysteretic Structures
DEFF Research Database (Denmark)
Lazarov, Boyan Stefanov
2003-01-01
The object of the study is a fast simulation method for generation and analysis of the plastic response of a randomly excited MDOF oscillatro with several potential elements with elasto-plastic constitutive behavior. The oscillator is statically determinate with linear damping. The external...... that are interesting for the plastic displacement process. These parts are those that are in the vicinity of the points of crossing of the response from the elastic domain to the plastic domain. The principle of the method is to use the known response properties at the crossing points of the stationary Gaussian white...... noise excited linear oscillator obtained from the elasto-plastic oscillator by totally removing the plastic domain. Thus the key to the applicability of the method is that the oscillator has a linear domain within which the response stays for a sufficiently long time to make the random response behave...
Directory of Open Access Journals (Sweden)
Jovanir Inês Müller Fernandes
2017-09-01
Full Text Available The aim of the study was to evaluate the efficacy of a nutritional formulation based on amino acids and vitamins supplemented in the drinking water for chicks in the first week of life subjected to thermal oscillation on performance, organ development and intestinal morphometry from 1 to 21 days. 640-male broiler chicks were distributed in a 2x2 factorial completely randomized design (with or without dietary supplementation and at comfort temperature or thermal oscillation. Chicks subjected to thermal oscillation presented worse performance (p < 0.05 than those under thermal comfort of 1 to 7, 1 to 14 and 1 to 21 days. Nutritional supplementation did not alter the performance (p < 0.05 of the birds, but resulted in a higher body weight (p < 0.05 regardless of the environmental thermal condition. At 7 days, chicks under thermal comfort had better intestinal morphometric parameters (p < 0.05, in relation to birds under thermal oscillation. In conclusion, the temperature oscillations caused negative consequences to the productive performance and the intestinal morphology of chicks for which dietary supplementation was not enough to mitigate the effects of the environmental challenge during the first week of life of the birds.
Location identification of closed crack based on Duffing oscillator transient transition
Liu, Xiaofeng; Bo, Lin; Liu, Yaolu; Zhao, Youxuan; Zhang, Jun; Deng, Mingxi; Hu, Ning
2018-02-01
The existence of a closed micro-crack in plates can be detected by using the nonlinear harmonic characteristics of the Lamb wave. However, its location identification is difficult. By considering the transient nonlinear Lamb under the noise interference, we proposed a location identification method for the closed crack based on the quantitative measurement of Duffing oscillator transient transfer in the phase space. The sliding short-time window was used to create a window truncation of to-be-detected signal. And then, the periodic extension processing for transient nonlinear Lamb wave was performed to ensure that the Duffing oscillator has adequate response time to reach a steady state. The transient autocorrelation method was used to reduce the occurrence of missed harmonic detection due to the random variable phase of nonlinear Lamb wave. Moreover, to overcome the deficiency in the quantitative analysis of Duffing system state by phase trajectory diagram and eliminate the misjudgment caused by harmonic frequency component contained in broadband noise, logic operation method of oscillator state transition function based on circular zone partition was adopted to establish the mapping relation between the oscillator transition state and the nonlinear harmonic time domain information. Final state transition discriminant function of Duffing oscillator was used as basis for identifying the reflected and transmitted harmonics from the crack. Chirplet time-frequency analysis was conducted to identify the mode of generated harmonics and determine the propagation speed. Through these steps, accurate position identification of the closed crack was achieved.
Atypical transistor-based chaotic oscillators: Design, realization, and diversity
Minati, Ludovico; Frasca, Mattia; OświÈ©cimka, Paweł; Faes, Luca; DroŻdŻ, Stanisław
2017-07-01
In this paper, we show that novel autonomous chaotic oscillators based on one or two bipolar junction transistors and a limited number of passive components can be obtained via random search with suitable heuristics. Chaos is a pervasive occurrence in these circuits, particularly after manual adjustment of a variable resistor placed in series with the supply voltage source. Following this approach, 49 unique circuits generating chaotic signals when physically realized were designed, representing the largest collection of circuits of this kind to date. These circuits are atypical as they do not trivially map onto known topologies or variations thereof. They feature diverse spectra and predominantly anti-persistent monofractal dynamics. Notably, we recurrently found a circuit comprising one resistor, one transistor, two inductors, and one capacitor, which generates a range of attractors depending on the parameter values. We also found a circuit yielding an irregular quantized spike-train resembling some aspects of neural discharge and another one generating a double-scroll attractor, which represent the smallest known transistor-based embodiments of these behaviors. Through three representative examples, we additionally show that diffusive coupling of heterogeneous oscillators of this kind may give rise to complex entrainment, such as lag synchronization with directed information transfer and generalized synchronization. The replicability and reproducibility of the experimental findings are good.
Synchrony-optimized networks of Kuramoto oscillators with inertia
Pinto, Rafael S.; Saa, Alberto
2016-12-01
We investigate synchronization in networks of Kuramoto oscillators with inertia. More specifically, we introduce a rewiring algorithm consisting basically in a hill climb scheme in which the edges of the network are swapped in order to enhance its synchronization capacity. We show that the synchrony-optimized networks generated by our algorithm have some interesting topological and dynamical properties. In particular, they typically exhibit an anticipation of the synchronization onset and are more robust against certain types of perturbations. We consider synthetic random networks and also a network with a topology based on an approximated model of the (high voltage) power grid of Spain, since networks of Kuramoto oscillators with inertia have been used recently as simplified models for power grids, for which synchronization is obviously a crucial issue. Despite the extreme simplifications adopted in these models, our results, among others recently obtained in the literature, may provide interesting principles to guide the future growth and development of real-world grids, specially in the case of a change of the current paradigm of centralized towards distributed generation power grids.
Spintronics r.f. oscillator driven by magnetic field feedback
Tulapurkar, Ashwin; Dixit, Dinesh; Konishi, Katsunori; Tomy, C. V.; Suzuki, Yoshishige
2013-03-01
Magnetic tunnel junctions (MTJ) can be used as nano-scale rf oscillators using spin-transfer torque effect. Here we present an alternative novel mechanism of ``magnetic field feedback'' for driving MTJs into precessional states. To realize this effect, MTJ needs to be fabricated on top of a co-planar wave-guide. A dc current is passed through MTJ to produce a fluctuating voltage across it as a combination of thermal fluctuations of free layer and magneto-resistance effect. This voltage is applied across co-planar wave-guide to create a fluctuating magnetic field which acts on the free layer to enhance its fluctuations. If the dc current exceeds a critical value, precessional states of free layer are excited. We have derived expression for the critical current using lineralized LLG equation, modified to include the ``feedback'' magnetic field. We have verified the feedback effect by numerical simulation of stochastic LLG equation including random magnetic field: we find that the damping of the free layer can be increased/decreased by applying -ve/ +ve dc current. Simulations show that by applying dc current more than critical current, large amplitude oscillations with high quality factors are possible.
Energy Technology Data Exchange (ETDEWEB)
Rosu, H.C., E-mail: hcr@ipicyt.edu.mx [IPICyT, Instituto Potosino de Investigacion Cientifica y Tecnologica, Apdo Postal 3-74 Tangamanga, 78231 San Luis Potosi, S.L.P. (Mexico); Khmelnytskaya, K.V. [Universidad Autonoma de Queretaro, Centro Universitario, Cerro de las Campanas s/n, C.P. 76010 Santiago de Queretaro, Qro. (Mexico)
2011-09-19
We determine the kind of parametric oscillators that are generated in the usual factorization procedure of second-order linear differential equations when one introduces a constant shift of the Riccati solution of the classical harmonic oscillator. The mathematical results show that some of these oscillators could be of physical nature. We give the solutions of the obtained second-order differential equations and the values of the shift parameter providing strictly periodic and antiperiodic solutions. We also notice that this simple problem presents parity-time (PT) symmetry. Possible applications are mentioned. -- Highlights: → A particular Riccati solution of the classical harmonic oscillator is shifted by a constant. → Such a solution is used in the factorization brackets to get different equations of motion. → The properties of the parametric oscillators obtained in this way are examined.
Nonlinear Analysis of Ring Oscillator and Cross-Coupled Oscillator Circuits
Ge, Xiaoqing
2010-12-01
Hassan Khalil’s research results and beautifully written textbook on nonlinear systems have influenced generations of researchers, including the authors of this paper. Using nonlinear systems techniques, this paper analyzes ring oscillator and cross-coupled oscillator circuits, which are essential building blocks in digital systems. The paper first investigates local and global stability properties of an n-stage ring oscillator by making use of its cyclic structure. It next studies global stability properties of a class of cross-coupled oscillators which admit the representation of a dynamic system in feedback with a static nonlinearity, and presents su cient conditions for almost global convergence of the solutions to a limit cycle when the feedback gain is in the vicinity of a bifurcation point. The result are also extended to the synchronization of interconnected identical oscillator circuits.
Oscillations in atmospheric water above Switzerland
Hocke, Klemens; Navas-Guzmán, Francisco; Moreira, Lorena; Bernet, Leonie; Mätzler, Christian
2017-10-01
Cloud fraction (CF), integrated liquid water (ILW) and integrated water vapour (IWV) were continuously measured from 2004 to 2016 by the TROpospheric WAter RAdiometer (TROWARA) in Bern, Switzerland. There are indications for interannual variations of CF and ILW. A spectral analysis shows that IWV is dominated by an annual oscillation, leading to an IWV maximum of 24 kg m-2 in July to August and a minimum of 8 kg m-2 in February. The seasonal behaviour of CF and ILW is composed by both the annual and the semiannual oscillation. However, the annual oscillation of CF has a maximum in December while the annual oscillation of ILW has a maximum in July. The semiannual oscillations of CF and ILW are strong from 2010 to 2014. The normalized power spectra of ILW and CF show statistically significant spectral components with periods of 76, 85, 97 and 150 days. We find a similarity between the power spectra of ILW and CF with those of zonal wind at 830 hPa (1.5 km) above Bern. Particularly, the occurrence of higher harmonics in the CF and ILW spectra is possibly forced by the behaviour of the lower-tropospheric wind. The mean amplitude spectra of CF, ILW and IWV show increased short-term variability on timescales less than 40 days from spring to fall. We find a weekly cycle of CF and ILW from June to September with increased values on Saturday, Sunday and Monday.
Antineutrino Oscillations in the Atmospheric Sector
Energy Technology Data Exchange (ETDEWEB)
Himmel, Alexander I. [California Inst. of Technology (CalTech), Pasadena, CA (United States)
2011-05-01
This thesis presents measurements of the oscillations of muon antineutrinos in the atmospheric sector, where world knowledge of antineutrino oscillations lags well behind the knowledge of neutrinos, as well as a search for v_{μ} → $\\bar{v}$_{μ} transitions. Differences between neutrino and antineutrino oscillations could be a sign of physics beyond the Standard Model, including non-standard matter interactions or the violation of CPT symmetry. These measurements leverage the sign-selecting capabilities of the magnetized steel-scintillator MINOS detectors to analyze antineutrinos from the NuMI beam, both when it is in neutrino-mode and when it is in antineutrino-mode. Antineutrino oscillations are observed at |Δ$\\bar{m}$_{atm} ^{2}| = (3.36_{-0.40}^{+0.46}(stat) ± 0.06(syst)) x 10^{-3} eV^{2} and sin^{2}(2$\\bar{θ}$_{23}) = 0.860_{-0.12}^{+0.11}(stat) ± 0.01(syst). The oscillation parameters measured for antineutrinos and those measured by MINOS for neutrinos differ by a large enough margin that the chance of obtaining two values as discrepant as those observed is only 2%, assuming the two measurements arise from the same underlying mechanism, with the same parameter values. No evidence is seen for neutrino-to-antineutrino transitions.
Fractional Dynamics in Calcium Oscillation Model
Directory of Open Access Journals (Sweden)
Yoothana Suansook
2015-01-01
Full Text Available The calcium oscillations have many important roles to perform many specific functions ranging from fertilization to cell death. The oscillation mechanisms have been observed in many cell types including cardiac cells, oocytes, and hepatocytes. There are many mathematical models proposed to describe the oscillatory changes of cytosolic calcium concentration in cytosol. Many experiments were observed in various kinds of living cells. Most of the experimental data show simple periodic oscillations. In certain type of cell, there exists the complex periodic bursting behavior. In this paper, we have studied further the fractional chaotic behavior in calcium oscillations model based on experimental study of hepatocytes proposed by Kummer et al. Our aim is to explore fractional-order chaotic pattern in this oscillation model. Numerical calculation of bifurcation parameters is carried out using modified trapezoidal rule for fractional integral. Fractional-order phase space and time series at fractional order are present. Numerical results are characterizing the dynamical behavior at different fractional order. Chaotic behavior of the model can be analyzed from the bifurcation pattern.
Viewing Majorana Bound States by Rabi Oscillations.
Wang, Zhi; Liang, Qi-Feng; Yao, Dao-Xin; Hu, Xiao
2015-07-08
We propose to use Rabi oscillation as a probe to view the fractional Josepshon relation (FJR) associated with Majorana bound states (MBSs) expected in one-dimensional topological superconductors. The system consists of a quantum dot (QD) and an rf-SQUID with MBSs at the Josephson junction. Rabi oscillations between energy levels formed by MBSs are induced by ac gate voltage controlling the coupling between QD and MBS when the photon energy proportional to the ac frequency matches gap between quantum levels formed by MBSs and QD. As a manifestation of the Rabi oscillation in the whole system involving MBSs, the electron occupation on QD oscillates with time, which can be measured by charge sensing techniques. With Floquet theorem and numerical analysis we reveal that from the resonant driving frequency for coherent Rabi oscillation one can directly map out the FJR cos(πΦ/Φ0) as a signature of MBSs, with Φ the magnetic flux through SQUID and Φ0 = hc/2e the flux quantum. The present scheme is expected to provide a clear evidence for MBSs under intensive searching.
Pattern recognition with simple oscillating circuits
Hölzel, R. W.; Krischer, K.
2011-07-01
Neural network devices that inherently possess parallel computing capabilities are generally difficult to construct because of the large number of neuron-neuron connections. However, there exists a theoretical approach (Hoppensteadt and Izhikevich 1999 Phys. Rev. Lett. 82 2983) that forgoes the individual connections and uses only a global coupling: systems of weakly coupled oscillators with a time-dependent global coupling are capable of performing pattern recognition in an associative manner similar to Hopfield networks. The information is stored in the phase shifts of the individual oscillators. However, to date, even the feasibility of controlling phase shifts with this kind of coupling has not yet been established experimentally. We present an experimental realization of this neural network device. It consists of eight sinusoidal electrical van der Pol oscillators that are globally coupled through a variable resistor with the electric potential as the coupling variable. We estimate an effective value of the phase coupling strength in our experiment. For that, we derive a general approach that allows one to compare different experimental realizations with each other as well as with phase equation models. We demonstrate that individual phase shifts of oscillators can be experimentally controlled by a weak global coupling. Furthermore, supplied with a distorted input image, the oscillating network can indeed recognize the correct image out of a set of predefined patterns. It can therefore be used as the processing unit of an associative memory device.
Microbiota Diurnal Rhythmicity Programs Host Transcriptome Oscillations.
Thaiss, Christoph A; Levy, Maayan; Korem, Tal; Dohnalová, Lenka; Shapiro, Hagit; Jaitin, Diego A; David, Eyal; Winter, Deborah R; Gury-BenAri, Meital; Tatirovsky, Evgeny; Tuganbaev, Timur; Federici, Sara; Zmora, Niv; Zeevi, David; Dori-Bachash, Mally; Pevsner-Fischer, Meirav; Kartvelishvily, Elena; Brandis, Alexander; Harmelin, Alon; Shibolet, Oren; Halpern, Zamir; Honda, Kenya; Amit, Ido; Segal, Eran; Elinav, Eran
2016-12-01
The intestinal microbiota undergoes diurnal compositional and functional oscillations that affect metabolic homeostasis, but the mechanisms by which the rhythmic microbiota influences host circadian activity remain elusive. Using integrated multi-omics and imaging approaches, we demonstrate that the gut microbiota features oscillating biogeographical localization and metabolome patterns that determine the rhythmic exposure of the intestinal epithelium to different bacterial species and their metabolites over the course of a day. This diurnal microbial behavior drives, in turn, the global programming of the host circadian transcriptional, epigenetic, and metabolite oscillations. Surprisingly, disruption of homeostatic microbiome rhythmicity not only abrogates normal chromatin and transcriptional oscillations of the host, but also incites genome-wide de novo oscillations in both intestine and liver, thereby impacting diurnal fluctuations of host physiology and disease susceptibility. As such, the rhythmic biogeography and metabolome of the intestinal microbiota regulates the temporal organization and functional outcome of host transcriptional and epigenetic programs. Copyright Â© 2016 Elsevier Inc. All rights reserved.
The vertical oscillations of coupled magnets
Energy Technology Data Exchange (ETDEWEB)
Li Kewei; Lin Jiahuang; Kang Zi Yang [Raffles Institution, 1 Raffles Institution Lane, Singapore 575954 (Singapore); Liang, Samuel Yee Wei [Anglo-Chinese School Independent, 121 Dover Road, Singapore 139650 (Singapore); Juan, Jeremias Wong Say, E-mail: likewei92@gmail.com [NUS High School of Mathematics and Science, 20 Clementi Avenue 1, Singapore 129957 (Singapore)
2011-07-15
The International Young Physicists' Tournament (IYPT) is a worldwide, annual competition for high school students. This paper is adapted from the winning solution to Problem 14, Magnetic Spring, as presented in the final round of the 23rd IYPT in Vienna, Austria. Two magnets were arranged on top of each other on a common axis. One was fixed, while the other could move vertically. Various parameters of interest were investigated, including the effective gravitational acceleration, the strength, size, mass and geometry of the magnets, and damping of the oscillations. Despite its simplicity, this setup yielded a number of interesting and unexpected relations. The first stage of the investigation was concerned only with the undamped oscillations of small amplitudes, and the period of small amplitude oscillations was found to be dependent only on the eighth root of important magnet properties such as its strength and mass. The second stage sought to investigate more general oscillations. A numerical model which took into account magnet size, magnet geometry and damping effects was developed to model the general oscillations. Air resistance and friction were found to be significant sources of damping, while eddy currents were negligible.
Human gamma oscillations during slow wave sleep.
Directory of Open Access Journals (Sweden)
Mario Valderrama
Full Text Available Neocortical local field potentials have shown that gamma oscillations occur spontaneously during slow-wave sleep (SWS. At the macroscopic EEG level in the human brain, no evidences were reported so far. In this study, by using simultaneous scalp and intracranial EEG recordings in 20 epileptic subjects, we examined gamma oscillations in cerebral cortex during SWS. We report that gamma oscillations in low (30-50 Hz and high (60-120 Hz frequency bands recurrently emerged in all investigated regions and their amplitudes coincided with specific phases of the cortical slow wave. In most of the cases, multiple oscillatory bursts in different frequency bands from 30 to 120 Hz were correlated with positive peaks of scalp slow waves ("IN-phase" pattern, confirming previous animal findings. In addition, we report another gamma pattern that appears preferentially during the negative phase of the slow wave ("ANTI-phase" pattern. This new pattern presented dominant peaks in the high gamma range and was preferentially expressed in the temporal cortex. Finally, we found that the spatial coherence between cortical sites exhibiting gamma activities was local and fell off quickly when computed between distant sites. Overall, these results provide the first human evidences that gamma oscillations can be observed in macroscopic EEG recordings during sleep. They support the concept that these high-frequency activities might be associated with phasic increases of neural activity during slow oscillations. Such patterned activity in the sleeping brain could play a role in off-line processing of cortical networks.
Search for b^0s oscillations in semileptonic b decays
Energy Technology Data Exchange (ETDEWEB)
Gomez-Ceballos, Guillelmo; /Cantabria Inst. of Phys.
2007-02-01
This note describes a search for B{sub s}{sup 0} oscillations using semileptonic B decays recorded by the CDF detector during Run II of the Fermilab Tevatron Collider on about 1 fb{sup -1} of data, as it was in April 2006. Opposite-side and same-side b flavor taggers are used in this analysis. First they measure the B{sup 0} oscillation frequency and calibrate opposite-side b flavor taggers on a sample of semileptonic B decays. A simultaneous analysis of B{sup 0} and B{sup +} decays to {ell}D{sup 0}, {ell}D{sup +} and {ell}D* final states has been performed. Beginning with tagger calibrations available from earlier analyses on the {ell} + SVT samples, they use the high statistic {ell}D sample to derive scale factors for predicted dilutions of the soft muon, soft electron and jet charge opposite-side taggers. Secondly they reconstruct B{sub s}{sup 0} {yields} {ell}{sup +}D{sub s}{sup -}X decays in three different D{sub s}{sup -} channels, namely {phi}{pi}{sup -}, K*{sup 0} K{sup -} and {pi}{sup +}{pi}{sup -}{pi}{sup -}. D mass, lepton-D mass and lifetime parameters for signal and backgrounds are determined with unbinned maximum likelihood fits. They validate their fitter and obtain sensitivity projections with toy Monte Carlo samples. The {Delta}m{sub s} sensitivity on the semileptonic sample is 17.3 ps{sup -1}. With the combination of the semileptonic and hadronic analyses they observe a signature consistent with B{sub s}{sup 0} - {bar B}{sup s}{sup 0} oscillations. The probability that random tags background could fluctuate to mimic such a signature is 0.5%. Under the hypothesis that this is a signal for B{sub s}{sup 0} - {bar B}{sup s}{sup 0} oscillations, they measure {Delta}m{sub s} = 17.31{sub -0.18}{sup -0.33}(stat.) {+-} 0.07(syst.) ps{sup -1}.
A random dynamical systems perspective on stochastic resonance
Cherubini, Anna Maria; Lamb, Jeroen S. W.; Rasmussen, Martin; Sato, Yuzuru
2017-07-01
We study stochastic resonance in an over-damped approximation of the stochastic Duffing oscillator from a random dynamical systems point of view. We analyse this problem in the general framework of random dynamical systems with a nonautonomous forcing. We prove the existence of a unique global attracting random periodic orbit and a stationary periodic measure. We use the stationary periodic measure to define an indicator for the stochastic resonance.
A random dynamical systems perspective on stochastic resonance
Cherubini, Anna Maria; Lamb, Jeroen S. W.; Rasmussen, Martin; Sato, Yuzuru
2015-01-01
We study stochastic resonance in an over-damped approximation of the stochastic Duffing oscillator from a random dynamical systems point of view. We analyse this problem in the general framework of random dynamical systems with a nonautonomous forcing. We prove the existence of a unique global attracting random periodic orbit and a stationary periodic measure. We use the stationary periodic measure to define an indicator for the stochastic resonance.
Oscillation of large air bubble cloud
Energy Technology Data Exchange (ETDEWEB)
Bae, Y.Y.; Kim, H.Y.; Park, J.K. [Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of)
2001-07-01
The behavior of a large air bubble cloud, which is generated by the air discharged from a perforated sparger, is analyzed by solving Rayleigh-Plesset equation, energy equations and energy balance equation. The equations are solved by Runge-Kutta integration and MacCormack finite difference method. Initial conditions such as driving pressure, air volume, and void fraction strongly affect the bubble pressure amplitude and oscillation frequency. The pool temperature has a strong effect on the oscillation frequency and a negligible effect on the pressure amplitude. The polytropic constant during the compression and expansion processes of individual bubbles ranges from 1.0 to 1.4, which may be attributed to the fact that small bubbles oscillated in frequencies different from their resonance. The temperature of the bubble cloud rapidly approaches the ambient temperature, as is expected from the polytropic constants being between 1.0 and 1.4. (authors)
Linear Isentropic Oscillations of Stars Theoretical Foundations
Smeyers, Paul
2010-01-01
The study of stellar oscillations is the preeminent way to investigate the stability of stars and to interpret their variability. The theory of the linear, isentropic oscillations of isolated gaseous stars, and thus of compressible spherically symmetric equilibrium configurations, has largely been developed from the viewpoint of the hypothesis of the physical radial pulsations of stars. Written for doctoral students and researchers, this monograph aims to provide a systematic and consistent survey of the fundamentals of the theory of free, linear, isentropic oscillations in spherically symmetric, gaseous equilibrium stars. The first part of the book presents basic concepts and equations, the distinction between spheroidal and toroidal normal modes, the solution of Poisson’s differential equation for the perturbation of the gravitational potential, and Hamilton’s variational principle. The second part is devoted to the possible existence of waves propagating in the radial direction, the origin and classifi...
Simulations of Oscillating Hydrofoils in Array Configurations
Franck, Jennifer; Simeski, Filip; Spaulding, Arianne
2016-11-01
The vortex and wake interactions of multiple oscillating foils are investigated computationally for energy harvesting applications. Oscillating with high pitch and heave amplitudes to maximize power production, the elliptical-shaped foils generate large coherent vortices at the leading and trailing edge, which are shed downstream to create a large highly structured wake of vortices with alternating sign. Downstream foils oscillate within the large organized wake at a relative phase angle to the lead foil such that power efficiency is optimized. When placed directly downstream of one another, the optimal phase of a second foil is to avoid interactions with the first foil's wake, generating less than half of the total power of the first foil. However, when placed in a staggered configuration the downstream foil has an increase in efficiency through constructive vortex-foil interactions. Funded by ARPAe.
Directional Transverse Oscillation Vector Flow Estimation
DEFF Research Database (Denmark)
Jensen, Jørgen Arendt
2017-01-01
A method for estimating vector velocities using transverse oscillation (TO) combined with directional beamforming is presented. In Directional Transverse Oscillation (DTO) a normal focused field is emitted and the received signals are beamformed in the lateral direction transverse to the ultrasound...... beam to increase the amount of data for vector velocity estimation. The approach is self-calibrating as the lateral oscillation period is estimated from the directional signal through a Fourier transform to yield quantitative velocity results over a large range of depths. The approach was extensively...... simulated using Field IIpro and implemented on the experimental SARUS scanner in connection with a BK Medical 8820e convex array transducer. Velocity estimates for DTO are found for beam-to-flow angles of 60, 75, and 90, and vessel depths from 24 to 156 mm. Using 16 emissions the Standard Deviation (SD...
Synchronization of Time-Continuous Chaotic Oscillators
DEFF Research Database (Denmark)
Yanchuk, S.; Maistrenko, Yuri; Mosekilde, Erik
2003-01-01
Considering a system of two coupled identical chaotic oscillators, the paper first establishes the conditions of transverse stability for the fully synchronized chaotic state. Periodic orbit threshold theory is applied to determine the bifurcations through which low-periodic orbits embedded...... in the fully synchronized state lose their transverse stability, and the appearance of globally and locally riddled basins of attraction is discussed, respectively, in terms of the subcritical, supercritical nature of the riddling bifurcations. We show how the introduction of a small parameter mismatch between...... the interacting chaotic oscillators causes a shift of the synchronization manifold. The presence of a coupling asymmetry is found to lead to further modifications of the destabilization process. Finally, the paper considers the problem of partial synchronization in a system of four coupled Rossler oscillators...
Quantum anharmonic oscillator: The airy function approach
Energy Technology Data Exchange (ETDEWEB)
Maiz, F., E-mail: fethimaiz@gmail.com [King Khalid University, Faculty of Science, Physics Department, PO Box 9004, Abha 61413, Asseer (Saudi Arabia); University of Cartage, Nabeul Engineering Preparatory Institute, Merazka, 8000 Nabeul (Tunisia); AlFaify, S. [King Khalid University, Faculty of Science, Physics Department, PO Box 9004, Abha 61413, Asseer (Saudi Arabia)
2014-05-15
New and simple numerical method is being reported to solve anharmonic oscillator problems. The method is setup to approach the real potential V(x) of the anharmonic oscillator system as a piecewise linear potential u(x) and to solve the Schrödinger equation of the system using the Airy function. Then, solutions continuity conditions lead to the energy quantification condition, and consequently, the energy eigenvalues. For testing purpose, the method was applied on the sextic and octic oscillators systems. The proposed method is found to be realistic, computationally simple, and having high degrees of accuracy. In addition, it can be applied to any form of potential. The results obtained by the proposed method were seen closely agreeing with results reached by other complicated methods.
Theoretical Interpretation of Current Neutrino Oscillation Data
Fogli, Gianluigi; Lisi, Eligio
We discuss the theoretical interpretation of neutrino oscillation data in terms of 3v and 4v mixing. Two-neutrino oscillations, often used to describe experimental results in a first approximation, are briefly recalled (Sect. 5.1). The main focus of our review is 3v mixing (Sect. 5.2), which accommodates both the negative results of oscillation searches at reactors (Sect. 5.3) and the evidence for flavor transitions obtained from atmospheric and solar neutrino data (Sects. 5.4 and 5.5). The status and problems of 4v scenarios embedding the additional LSND signal are also discussed (Sect. 5.7). Finally, we outline the impact of the very latest data (Sect. 5.8). Standard electroweak neutrino interactions are assumed in all cases; scenarios with nonstandard dynamics are beyond the scope of this review.
THERMAL OSCILLATIONS IN LIQUID HELIUM TARGETS.
Energy Technology Data Exchange (ETDEWEB)
WANG,L.; JIA,L.X.
2001-07-16
A liquid helium target for the high-energy physics was built and installed in the proton beam line at the Alternate Gradient Synchrotron of Brookhaven National Laboratory in 2001. The target flask has a liquid volume of 8.25 liters and is made of thin Mylar film. A G-M/J-T cryocooler of five-watts at 4.2K was used to produce liquid helium and refrigerate the target. A thermosyphon circuit for the target was connected to the J-T circuit by a liquid/gas separator. Because of the large heat load to the target and its long transfer lines, thermal oscillations were observed during the system tests. To eliminate the oscillation, a series of tests and analyses were carried out. This paper describes the phenomena and provides the understanding of the thermal oscillations in the target system.
Circadian oscillators in the mouse brain
DEFF Research Database (Denmark)
Rath, Martin F; Rovsing, Louise; Møller, Morten
2014-01-01
The circadian timekeeper of the mammalian brain resides in the suprachiasmatic nucleus of the hypothalamus (SCN), and is characterized by rhythmic expression of a set of clock genes with specific 24-h daily profiles. An increasing amount of data suggests that additional circadian oscillators...... residing outside the SCN have the capacity to generate peripheral circadian rhythms. We have recently shown the presence of SCN-controlled oscillators in the neocortex and cerebellum of the rat. The function of these peripheral brain clocks is unknown, and elucidating this could involve mice...... and granular cell layers of the cerebellar cortex of the mouse brain. Among these, Per1, Per2, Cry1, Arntl, and Nr1d1 exhibit circadian rhythms suggesting that local running circadian oscillators reside within neurons of the mouse neocortex and cerebellar cortex. The temporal expression profiles of clock genes...
The harmonic oscillator and nuclear physics
Rowe, D. J.
1993-01-01
The three-dimensional harmonic oscillator plays a central role in nuclear physics. It provides the underlying structure of the independent-particle shell model and gives rise to the dynamical group structures on which models of nuclear collective motion are based. It is shown that the three-dimensional harmonic oscillator features a rich variety of coherent states, including vibrations of the monopole, dipole, and quadrupole types, and rotations of the rigid flow, vortex flow, and irrotational flow types. Nuclear collective states exhibit all of these flows. It is also shown that the coherent state representations, which have their origins in applications to the dynamical groups of the simple harmonic oscillator, can be extended to vector coherent state representations with a much wider range of applicability. As a result, coherent state theory and vector coherent state theory become powerful tools in the application of algebraic methods in physics.
Self oscillating PWM modulators, a topological comparison
DEFF Research Database (Denmark)
Poulsen, Søren; Andersen, Michael Andreas E.
2004-01-01
's work with switch mode audio power amplifiers, where linear tracking of the reference signal is of major importance. Use of the modulator topologies presented are not limited to this kind of equipment, but can be used in a very wide range of applications from very low to very high power levels....... or fs/ð range respectively, where fs is the switching frequency of the converter. For some applications this will require unacceptable high switching frequency to achieve enough control loop bandwidth for the desired dynamic performance. With self oscillating modulators, the open loop bandwidth is equal...... or by shaping the open loop function of the modulator so its gain and phase response causes a closed loop natural oscillation. The two main types of self oscillating modulators have many similarities, but differences in dynamic performance and linearity are present. The work presented is related to the author...
New Realizations of Single OTRA-Based Sinusoidal Oscillators
Directory of Open Access Journals (Sweden)
Hung-Chun Chien
2014-01-01
Full Text Available This study proposes three new sinusoidal oscillators based on an operational transresistance amplifier (OTRA. Each of the proposed oscillator circuits consists of one OTRA combined with a few passive components. The first circuit is an OTRA-based minimum RC oscillator. The second circuit is capable of providing independent control on the condition of oscillation without affecting the oscillation frequency. The third circuit exhibits independent control of oscillation frequency through a capacitor. This study first introduces the OTRA and the related formulations of the proposed oscillator circuits, and then discusses the nonideal effects, sensitivity analyses, and frequency stability of the presented circuits. The proposed oscillators exhibit low sensitivities and good frequency stability. Because the presented circuits feature low impedance output, they can be connected directly to the next stage without cascading additional voltage buffers. HSPICE simulations and experimental results confirm the feasibility of the new oscillator circuits.
Patel, Vishal R; Ceglia, Nicholas; Zeller, Michael; Eckel-Mahan, Kristin; Sassone-Corsi, Paolo; Baldi, Pierre
2015-10-01
Circadian oscillations have been observed in animals, plants, fungi and cyanobacteria and play a fundamental role in coordinating the homeostasis and behavior of biological systems. Genetically encoded molecular clocks found in nearly every cell, based on negative transcription/translation feedback loops and involving only a dozen genes, play a central role in maintaining these oscillations. However, high-throughput gene expression experiments reveal that in a typical tissue, a much larger fraction ([Formula: see text]) of all transcripts oscillate with the day-night cycle and the oscillating species vary with tissue type suggesting that perhaps a much larger fraction of all transcripts, and perhaps also other molecular species, may bear the potential for circadian oscillations. To better quantify the pervasiveness and plasticity of circadian oscillations, we conduct the first large-scale analysis aggregating the results of 18 circadian transcriptomic studies and 10 circadian metabolomic studies conducted in mice using different tissues and under different conditions. We find that over half of protein coding genes in the cell can produce transcripts that are circadian in at least one set of conditions and similarly for measured metabolites. Genetic or environmental perturbations can disrupt existing oscillations by changing their amplitudes and phases, suppressing them or giving rise to novel circadian oscillations. The oscillating species and their oscillations provide a characteristic signature of the physiological state of the corresponding cell/tissue. Molecular networks comprise many oscillator loops that have been sculpted by evolution over two trillion day-night cycles to have intrinsic circadian frequency. These oscillating loops are coupled by shared nodes in a large network of coupled circadian oscillators where the clock genes form a major hub. Cells can program and re-program their circadian repertoire through epigenetic and other mechanisms. High
Electroacoustic oscillations in the LEP SC. cavities
Boussard, Daniel; Tückmantel, Joachim
1996-01-01
The LEP superconducting cavities have been plagued by electroacoustic oscillations. Tests have been done to eliminate these by a special feed-back loop in the tuning circuit as well as a feed-forward path, but they could only be eliminated safely up to the design field by running the cavities close to tune neglecting beam-loading compensation. This technique proved successful during the first LEP2 test run at 70 GeV. The mechanism and essential parameters driving these oscillations have been analysed as well as the corresponding stronger loading of the power coupler.
Solar Dynamo Driven by Periodic Flow Oscillation
Mayr, Hans G.; Hartle, Richard E.; Einaudi, Franco (Technical Monitor)
2001-01-01
We have proposed that the periodicity of the solar magnetic cycle is determined by wave mean flow interactions analogous to those driving the Quasi Biennial Oscillation in the Earth's atmosphere. Upward propagating gravity waves would produce oscillating flows near the top of the radiation zone that in turn would drive a kinematic dynamo to generate the 22-year solar magnetic cycle. The dynamo we propose is built on a given time independent magnetic field B, which allows us to estimate the time dependent, oscillating components of the magnetic field, (Delta)B. The toroidal magnetic field (Delta)B(sub phi) is directly driven by zonal flow and is relatively large in the source region, (Delta)(sub phi)/B(sub Theta) much greater than 1. Consistent with observations, this field peaks at low latitudes and has opposite polarities in both hemispheres. The oscillating poloidal magnetic field component, (Delta)B(sub Theta), is driven by the meridional circulation, which is difficult to assess without a numerical model that properly accounts for the solar atmosphere dynamics. Scale-analysis suggests that (Delta)B(sub Theta) is small compared to B(sub Theta) in the dynamo region. Relative to B(sub Theta), however, the oscillating magnetic field perturbations are expected to be transported more rapidly upwards in the convection zone to the solar surface. As a result, (Delta)B(sub Theta) (and (Delta)B(sub phi)) should grow relative to B(sub Theta), so that the magnetic fields reverse at the surface as observed. Since the meridional and zonai flow oscillations are out of phase, the poloidal magnetic field peaks during times when the toroidal field reverses direction, which is observed. With the proposed wave driven flow oscillation, the magnitude of the oscillating poloidal magnetic field increases with the mean rotation rate of the fluid. This is consistent with the Bode-Blackett empirical scaling law, which reveals that in massive astrophysical bodies the magnetic moment tends
Neutrino oscillations in the early Universe
Kirilova, Daniela P
2001-01-01
We discuss the oscillations effects on neutrinos in the early Universe and update the cosmological constraints on the oscillation parameters. It is shown that sterile LOW solution to the solar neutrino problem is almost completely excluded from cosmological nucleosynthesis considerations. Two possibilities for the relaxation of this constraint are discussed: high primordial helium-4 yield and a relic lepton asymmetry present at nucleosynthesis epoch. The numerical analysis proved that Y_p=0.25 only relaxes the constraint on LOW solution, while L > 10^{-5} is capable to remove it.
Upward-going muons and neutrino oscillations
Fogli, G. L.; Lisi, E.; Marrone, A.
1998-05-01
The available upward-going muon data from the Kamiokande, Baksan, MACRO, IMB, and SuperKamiokande experiments are reviewed and combined. Bounds on the neutrino mass and mixing parameters are derived for oscillations in two and three flavors. These bounds are not in significant conflict with the oscillation solution to the atmospheric neutrino flavor anomaly observed in the sub-GeV and multi-GeV energy range. The combination of all the available atmospheric data tends to favor the νμνe channel with respect to the νμντ channel, and to disfavor the threefold maximal mixing scenario.
Power Oscillations Damping in DC Microgrids
DEFF Research Database (Denmark)
Hamzeh, Mohsen; Ghafouri, Mohsen; Karimi, Houshang
2016-01-01
This paper proposes a new control strategy for damping of power oscillations in a multi-source dc microgrid. A parallel combination of a fuel cell (FC), a photovoltaic (PV) system and a supercapacitor (SC) are used as a hybrid power conversion system (HPCS). The SC compensates for the slow...... transient response of the FC stack. The HPCS controller comprises a multi-loop voltage controller and a virtual impedance loop for power management. The virtual impedance loop uses a dynamic droop gain to actively damp the low-frequency oscillations of the power sharing control unit. The gain of virtual...
Phase locking between Josephson soliton oscillators
DEFF Research Database (Denmark)
Holst, T.; Hansen, Jørn Bindslev; Grønbech-Jensen, N.
1990-01-01
We report observations of phase-locking phenomena between two Josephson soliton (fluxon) oscillators biased in self-resonant modes. The locking strength was measured as a function of bias conditions. A frequency tunability of the phase-locked oscillators up to 7% at 10 GHz was observed. Two coupled...... perturbed sine-Gordon equations were derived from an equivalent circuit consisting of inductively coupled, nonlinear, lossy transmission lines. These equations were solved numerically to find the locking regions. Good qualitative agreement was found between the experimental results and the calculations...
Hyperbolic geometry of Kuramoto oscillator networks
Chen, Bolun; Engelbrecht, Jan R.; Mirollo, Renato
2017-09-01
Kuramoto oscillator networks have the special property that their trajectories are constrained to lie on the (at most) 3D orbits of the Möbius group acting on the state space T N (the N-fold torus). This result has been used to explain the existence of the N-3 constants of motion discovered by Watanabe and Strogatz for Kuramoto oscillator networks. In this work we investigate geometric consequences of this Möbius group action. The dynamics of Kuramoto phase models can be further reduced to 2D reduced group orbits, which have a natural geometry equivalent to the unit disk \
NOx Emission Reduction by Oscillating Combustion
Energy Technology Data Exchange (ETDEWEB)
John C. Wagner
2004-03-31
High-temperature, natural gas-fired furnaces, especially those fired with preheated air, produce large quantities of NO{sub x} per ton of material processed. Regulations on emissions from industrial furnaces are becoming increasingly more stringent. In addition, competition is forcing operators to make their furnaces more productive and/or efficient. Switching from preheated air to industrial oxygen can increase efficiency and reduce NO{sub x}, but oxygen is significantly more costly than air and may not be compatible with the material being heated. What was needed, and what was developed during this project, is a technology that reduces NO{sub x} emissions while increasing furnace efficiency for both air- and oxy-fired furnaces. Oscillating combustion is a retrofit technology that involves the forced oscillation of the fuel flow rate to a furnace. These oscillations create successive, fuel-rich and fuel-lean zones within the furnace. Heat transfer from the flame to the load increases due to the more luminous fuel-rich zones, a longer overall flame length, and the breakup of the thermal boundary layer. The increased heat transfer shortens heat up times, thereby increasing furnace productivity, and reduces the heat going up the stack, thereby increasing efficiency. The fuel-rich and fuel-lean zones also produce substantially less NO{sub x} than firing at a constant excess air level. The longer flames and higher heat transfer rate reduces overall peak flame temperature and thus reduces additional NO{sub x} formation from the eventual mixing of the zones and burnout of combustibles from the rich zones. This project involved the development of hardware to implement oscillating combustion on an industrial scale, the laboratory testing of oscillating combustion on various types of industrial burners, and the field testing of oscillating combustion on several types of industrial furnace. Before laboratory testing began, a market study was conducted, based on the
NOx Emission Reduction by Oscillating combustion
Energy Technology Data Exchange (ETDEWEB)
Institute of Gas Technology
2004-01-30
High-temperature, natural gas-fired furnaces, especially those fired with preheated air, produce large quantities of NO{sub x} per ton of material processed. Regulations on emissions from industrial furnaces are becoming increasingly more stringent. In addition, competition is forcing operators to make their furnaces more productive and/or efficient. Switching from preheated air to industrial oxygen can increase efficiency and reduce NO{sub x}, but oxygen is significantly more costly than air and may not be compatible with the material being heated. What was needed, and what was developed during this project, is a technology that reduces NO{sub x} emissions while increasing furnace efficiency for both air- and oxy-fired furnaces. Oscillating combustion is a retrofit technology that involves the forced oscillation of the fuel flow rate to a furnace. These oscillations create successive, fuel-rich and fuel-lean zones within the furnace. Heat transfer from the flame to the load increases due to the more luminous fuel-rich zones, a longer overall flame length, and the breakup of the thermal boundary layer. The increased heat transfer shortens heat up times, thereby increasing furnace productivity, and reduces the heat going up the stack, thereby increasing efficiency. The fuel-rich and fuel-lean zones also produce substantially less NO{sub x} than firing at a constant excess air level. The longer flames and higher heat transfer rate reduces overall peak flame temperature and thus reduces additional NO{sub x} formation from the eventual mixing of the zones and burnout of combustibles from the rich zones. This project involved the development of hardware to implement oscillating combustion on an industrial scale, the laboratory testing of oscillating combustion on various types of industrial burners, and the field testing of oscillating combustion on several types of industrial furnace. Before laboratory testing began, a market study was conducted, based on the
Neutrino Oscillations Present Status and Future Plans
Thomas, Jennifer
2008-01-01
This book reviews the status of a very exciting field - neutrino oscillations - at a very important time. The fact that neutrinos have mass has only been proved in the last few years and the acceptance of that fact has opened up a whole new area of study to understand the fundamental parameters of the mixing matrix. The book summarizes the results from all the experiments which have played a role in the measurement of neutrino oscillations and briefly describes the scope of some new planned experiments. Contributions include a theoretical introduction by Stephen Parke from FNAL, as well as art
Interaction of low- and high-frequency oscillations in resonant systems with distributed interaction
Bulgakov, S. A.; Vavriv, D. M.
1991-03-01
The oscillation dynamics of synchronized resonant oscillators with distributed interaction in the presence of LF modulation of the beam is analyzed. It is shown that the interaction of LF and HF oscillations can lead to the excitation of stochastic oscillations. Conditions and scenarios of the generation of such oscillations are established for oscillators with soft and hard oscillation-excitation modes.
Multifrequency Oscillator-Type Active Printed Antenna Using Chaotic Colpitts Oscillator
Directory of Open Access Journals (Sweden)
Bibha Kumari
2014-01-01
Full Text Available This paper presents a new concept to realize a multifrequency Oscillator-type active printed monopole antenna. The concept of period doubling route to chaos is exploited to generate the multiple frequencies. The chaotic Colpitts oscillator is integrated with the printed monopole antenna (PMA on the same side of the substrate to realize an Oscillator-type active antenna where the PMA acts as a load and radiator to the chaotic oscillator. By changing the bias voltage of the oscillator, the antenna can be made to operate at single or multiple frequencies. To test the characteristics of the antenna at single and multiple frequencies of operation, two similar prototype models of printed monopole broadband antennas are developed. One of these antennas used at transmit side is fed by the chaotic Colpitts oscillator while the other is used as the receive antenna. It is observed that the antenna receives single or multiple frequencies simultaneously for particular values of the bias voltage of the oscillator at the transmit end.
A family of memristor-based reactance-less oscillators
Zidan, Mohammed A.
2013-05-03
In this paper, we present for the first time a family of memristor-based reactance-less oscillators (MRLOs). The proposed oscillators require no reactive components, that is, inductors or capacitors, rather, the ‘resistance storage’ property of memristor is exploited to generate the oscillation. Different types of MRLO family are presented, and for each type, closed form expressions are derived for the oscillation condition, oscillation frequency, and range of oscillation. Derived equations are further verified using transient circuit simulations. A comparison between different MRLO types is also discussed. In addition, detailed fabrication steps of a memristor device and experimental results for the first MRLO physical realization are presented.
State space modeling of Memristor-based Wien oscillator
Talukdar, Abdul Hafiz Ibne
2011-12-01
State space modeling of Memristor based Wien \\'A\\' oscillator has been demonstrated for the first time considering nonlinear ion drift in Memristor. Time dependant oscillating resistance of Memristor is reported in both state space solution and SPICE simulation which plausibly provide the basis of realizing parametric oscillation by Memristor based Wien oscillator. In addition to this part Memristor is shown to stabilize the final oscillation amplitude by means of its nonlinear dynamic resistance which hints for eliminating diode in the feedback network of conventional Wien oscillator. © 2011 IEEE.
Generalized model for Memristor-based Wien family oscillators
Talukdar, Abdul Hafiz Ibne
2012-07-23
In this paper, we report the unconventional characteristics of Memristor in Wien oscillators. Generalized mathematical models are developed to analyze four members of the Wien family using Memristors. Sustained oscillation is reported for all types though oscillating resistance and time dependent poles are present. We have also proposed an analytical model to estimate the desired amplitude of oscillation before the oscillation starts. These Memristor-based oscillation results, presented for the first time, are in good agreement with simulation results. © 2011 Elsevier Ltd.
Frequency stabilization in nonlinear MEMS and NEMS oscillators
Lopez, Omar Daniel; Antonio, Dario
2014-09-16
An illustrative system includes an amplifier operably connected to a phase shifter. The amplifier is configured to amplify a voltage from an oscillator. The phase shifter is operably connected to a driving amplitude control, wherein the phase shifter is configured to phase shift the amplified voltage and is configured to set an amplitude of the phase shifted voltage. The oscillator is operably connected to the driving amplitude control. The phase shifted voltage drives the oscillator. The oscillator is at an internal resonance condition, based at least on the amplitude of the phase shifted voltage, that stabilizes frequency oscillations in the oscillator.
Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver
Directory of Open Access Journals (Sweden)
S. Coco
2008-01-01
Full Text Available This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase noise performance is obtained by using a very high Q dielectric resonator.
Polymerization and oscillation stuttering in a filamentous model of the subcellular Min oscillation
Rutenberg, Andrew; Sengupta, Supratim; Sain, Anirban; Derr, Julien
2011-03-01
We present a computational model of the E. coli Min oscillation that involves polymerization of MinD filaments followed by depolymerization stimulated by filament-end zones of MinE. Our stochastic model is fully three-dimensional, and tracks the diffusion and interactions of every MinD and MinE molecule. We recover self-organized Min oscillations. We investigate the experimental phenomenon of oscillation stuttering, which we relate to the disruption of MinE tip-binding at the filament scale.
Majorana wave-function oscillations, fermion parity switches, and disorder in Kitaev chains
Hegde, Suraj S.; Vishveshwara, Smitha
2016-09-01
We study the decay and oscillations of Majorana fermion wave functions and ground-state (GS) fermion parity in one-dimensional topological superconducting lattice systems. Using a Majorana transfer matrix method, we find that Majorana wave-function properties are encoded in the associated Lyapunov exponent, which in turn is the sum of two independent components: a "superconducting component," which characterizes the gap induced decay, and the "normal component," which determines the oscillations and response to chemical potential configurations. The topological phase transition separating phases with and without Majorana end modes is seen to be a cancellation of these two components. We show that Majorana wave-function oscillations are completely determined by an underlying nonsuperconducting tight-binding model and are solely responsible for GS fermion parity switches in finite-sized systems. These observations enable us to analytically chart out wave-function oscillations, the resultant GS parity configuration as a function of parameter space in uniform wires, and special parity switch points where degenerate zero energy Majorana modes are restored in spite of finite size effects. For disordered wires, we find that band oscillations are completely washed out leading to a second localization length for the Majorana mode and the remnant oscillations are randomized as per Anderson localization physics in normal systems. Our transfer matrix method further allows us to (i) reproduce known results on the scaling of midgap Majorana states and demonstrate the origin of its log-normal distribution, (ii) identify contrasting behavior of disorder-dependent GS parity switches for the cases of even versus odd number of lattice sites, and (iii) chart out the GS parity configuration and associated parity switch points as a function of disorder strength.
Roles of protein ubiquitination and degradation kinetics in biological oscillations.
Directory of Open Access Journals (Sweden)
Lida Xu
Full Text Available Protein ubiquitination and degradation play important roles in many biological functions and are associated with many human diseases. It is well known that for biochemical oscillations to occur, proper degradation rates of the participating proteins are needed. In most mathematical models of biochemical reactions, linear degradation kinetics has been used. However, the degradation kinetics in real systems may be nonlinear, and how nonlinear degradation kinetics affects biological oscillations are not well understood. In this study, we first develop a biochemical reaction model of protein ubiquitination and degradation and calculate the degradation rate against the concentration of the free substrate. We show that the protein degradation kinetics mainly follows the Michaelis-Menten formulation with a time delay caused by ubiquitination and deubiquitination. We then study analytically how the Michaelis-Menten degradation kinetics affects the instabilities that lead to oscillations using three generic oscillation models: 1 a positive feedback mediated oscillator; 2 a positive-plus-negative feedback mediated oscillator; and 3 a negative feedback mediated oscillator. In all three cases, nonlinear degradation kinetics promotes oscillations, especially for the negative feedback mediated oscillator, resulting in much larger oscillation amplitudes and slower frequencies than those observed with linear kinetics. However, the time delay due to protein ubiquitination and deubiquitination generally suppresses oscillations, reducing the amplitude and increasing the frequency of the oscillations. These theoretical analyses provide mechanistic insights into the effects of specific proteins in the ubiquitination-proteasome system on biological oscillations.
ROBUST CONTROL OF OSCILLATIONS IN AGRICULTURAL TRACTORS
DEFF Research Database (Denmark)
Andersen, T. O.; Hansen, M. R.; Conrad, Finn
2003-01-01
for agricultural tractors equiped with hicth and implements. A control strategy is developed to make the implement counteract the movement of the tractor and thereby reducing the pitching oscillation. The control strategy is based on a linear plant model with constant or slowly varying parameters. Using...
Influence of core electrons on plasmon oscillations
Lipparini, E.; Pederiva, Francesco
1993-09-01
Core electrons constitute a polarizable background which tends to screen the plasma oscillations. The influence of core electrons on plasmon dispersion is studied with sum rule techniques. Analytical expressions are derived for the surface plasmon of flat surfaces and of small metal particles. Core polarization explains semiquantitatively the blue-shift of the surface plasmon recently observed in silver systems.
Control of partial synchronization in chaotic oscillators
Indian Academy of Sciences (India)
2015-02-07
Feb 7, 2015 ... Abstract. A design of coupling is proposed to control partial synchronization in two chaotic oscil- lators in a driver–response mode. A control of synchrony between one response variables is made possible (a transition from a complete synchronization to antisynchronization via amplitude death and vice ...
Liquid Oscillations in a U-Tube
Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco; Navarro, Luis Barba
2018-01-01
In hydrostatics, pressure measurement with U-gauges and their relationship to density is a well-known experiment. Very little is studied or experimented with the dynamics of the movement of a liquid in a U-tube probably due to its theoretical complexity but, after all, it is a simple damped oscillating system. In this paper we present a relatively…
Synchronization of oscillators in complex networks
Indian Academy of Sciences (India)
This being the most conservative assumption will cover the largest class of oscillators including those which have multiple, disjoint α regions of stability as can ..... intake of food and energy which will be fruitful only if the new networks are a great improvement and provide the organisms some evolutionary advantages. In.
Parametric resonance in neutrino oscillations in matter
Indian Academy of Sciences (India)
simple exact analytic solution. We will discuss this solution in Д6Д 2 and 4. ..... metric resonance conditions with respect to variations of the nadir angle – has a simple explanation. It is related to the fact that, due to ..... see [8,17,18]. The analogy with a pendulum with vertically oscillating point of support was discussed in [11].
Chemical Oscillations-Basic Principles and Examples
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 2. Chemical Oscillations - Basic Principles and Examples ... Protein Science and Engineering Unit Institute of Microbial Technology Sector 39A Chandigarh 160 036; Department of Chemistry and Centre for Advanced Studies in Chemistry ...
Information cloning of harmonic oscillator coherent states
Indian Academy of Sciences (India)
Abstract. We show that in the case of unknown harmonic oscillator coherent states it is possible to achieve what we call perfect information cloning. By this we mean that it is still possible to make arbitrary number of copies of a state which has exactly the same information content as the original unknown coherent state.
Acoustic power measurements of oscillating flames
Valk, M.
1981-01-01
The acoustic power of an oscillating flame is measured. A turbulent premixed propane/air flame is situated near a pressure antinode of a standing wave in a laboratory combustion chamber. This standing wave is generated by a piston. The fluctuating heat release of the flame will supply acoustic power
Page 1 Anharmonic oscillators Acknowledgements Financial ...
Indian Academy of Sciences (India)
Anharmonic oscillators. Acknowledgements. Financial assistance of CSIR, India, is gratefully acknowledged. One of us (AKC) is also thankful to CSIR for providing a research associateship. References. 1 G Herzberg, Molecular spectra and molecular structure (Van Nostrand Reinhold, NY,. 1950) Vol 1. 2 C Kittel ...
On entanglement in neutrino mixing and oscillations
Energy Technology Data Exchange (ETDEWEB)
Blasone, Massimo; Dell' Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio, E-mail: blasone@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)
2010-06-01
We report on recent results about entanglement in the context of particle mixing and oscillations. We study in detail single-particle entanglement arising in two-flavor neutrino mixing. The analysis is performed first in the context of Quantum Mechanics, and then for the case of Quantum Field Theory.
Hyperchaotic circuit with damped harmonic oscillators
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
2001-01-01
A simple fourth-order hyperchaotic circuit with damped harmonic oscillators is described. ANP3 and PSpice simulations including an eigenvalue study of the linearized Jacobian are presented together with a hardware implementation. The circuit contains two inductors with series resistance, two ideal...
Information cloning of harmonic oscillator coherent states
Indian Academy of Sciences (India)
We show that in the case of unknown harmonic oscillator coherent statesit is possible to achieve what we call perfect information cloning. By this we mean that it is still possible to make arbitrary number of copies of a state which has exactly the same information content as the original unknown coherent state. By making use ...
Accelerator-based neutrino oscillation experiments
Energy Technology Data Exchange (ETDEWEB)
Harris, Deborah A.; /Fermilab
2007-12-01
Neutrino oscillations were first discovered by experiments looking at neutrinos coming from extra-terrestrial sources, namely the sun and the atmosphere, but we will be depending on earth-based sources to take many of the next steps in this field. This article describes what has been learned so far from accelerator-based neutrino oscillation experiments, and then describe very generally what the next accelerator-based steps are. In section 2 the article discusses how one uses an accelerator to make a neutrino beam, in particular, one made from decays in flight of charged pions. There are several different neutrino detection methods currently in use, or under development. In section 3 these are presented, with a description of the general concept, an example of such a detector, and then a brief discussion of the outstanding issues associated with this detection technique. Finally, section 4 describes how the measurements of oscillation probabilities are made. This includes a description of the near detector technique and how it can be used to make the most precise measurements of neutrino oscillations.
Recurring events. Power oscillations in BWRs
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-12-01
During almost two decennia, the recurrence of power oscillations in domestic and foreign BWRs has represented a challenge to one important design safety criterion, even if the occurred power oscillations have not resulted in conditions exceeding the specified fuel design limits. Several reasons may explain the recurrence. One reason has been a worldwide trend for an aggressive fuel economy optimisation, which from time to another has resulted in reduced core stability margins. Another reason relates to the analytical tools for prediction of core stability. These tools were scarce during many years. A third aspect is that adequate and reliable core monitors were not early available for installation at the plants. Issues related to power oscillations have during many years received attention from both the regulatory body and utilities, and from the fuel manufacturers. The present report provides examples of important corrective actions which support this conclusion. However, recent events indicate that the complex issue of BWR power oscillations has not been suitably solved, at least domestically.
A common oscillator for perceptual rivalries?
Carter, Olivia L; Pettigrew, John D
2003-01-01
Perceptual rivalry is an oscillation of conscious experience that takes place despite univarying. if ambiguous, sensory input. Much current interest is focused on the controversy over the neural site of binocular rivalry, a variety of perceptual rivalry for which a number of different cortical regions have been implicated. Debate continues over the relative role of higher levels of processing compared with primary visual cortex and the suggestion that different forms of rivalry involve different cortical areas. Here we show that the temporal pattern of disappearance and reappearance in motion-induced blindness (MIB) (Bonneh et al, 2001 Nature 411 798-801) is highly correlated with the pattern of oscillation reported during binocular rivalry in the same individual. This correlation holds over a wide range of inter-individual variation. Temporal similarity in the two phenomena was strikingly confirmed by the effects of the hallucinogen LSD, which produced the same, extraordinary, pattern of increased rhythmicity in both kinds of perceptual oscillation. Furthermore. MIB demonstrates the two properties previously considered characteristic of binocular rivalry. Namely the distribution of dominance periods can be approximated by a gamma distribution and, in line with Levelt's second proposition of binocular rivalry, predominance of one perceptual phase can be increased through a reduction in the predominance time of the opposing phase. We conclude that (i) MIB is a form of perceptual rivalry, and (ii) there may be a common oscillator responsible for timing aspects of all forms of perceptual rivalry.
The strange case of the "oscillating" catalysts
Busico, [No Value; Cipullo, R; Kretschmer, W; Talarico, G; Vacatello, M; Castelli, VV
2002-01-01
The field of stereoselective propene polymerization has been dramatically innovated by the discovery of homogeneous metallocene-based catalysts with well-defined and tunable molecular structure. Of all, "oscillating" metallocenes are probably the most ingenious and challenging example of catalyst
Novel candidate genes associated with hippocampal oscillations.
Jansen, R.; Timmerman, J.; Loos, M.; Spijker, S.; van Ooyen, A.; Brussaard, A.B.; Mansvelder, H.D.; Smit, A.B.; de Gunst, M.; Linkenkaer-Hansen, K.
2011-01-01
The hippocampus is critical for a wide range of emotional and cognitive behaviors. Here, we performed the first genome-wide search for genes influencing hippocampal oscillations. We measured local field potentials (LFPs) using 64-channel multi-electrode arrays in acute hippocampal slices of 29 BXD
Self-oscillating inverter with bipolar transistors
Baciu, I.; Cunţan, C. D.; Floruţa, M.
2016-02-01
The paper presents a self-oscillating inverter manufactured with bipolar transistors that supplies a high-amplitude alternating voltage to a fluorescent tube with a burned filament. The inverter is supplied from a low voltage accumulator that can be charged from a photovoltaic panel through a voltage regulator.
Neutrino oscillations: Recent results and future directions
Indian Academy of Sciences (India)
A brief introduction to the phenomena of vacuum neutrino oscillations and resonant flavour conversion is presented with a heavy pedagogic leaning. Variants of these ideas, e.g., neutrino helicity flip in a magnetic field, violation of the equivalence principle, etc. are outlined. A few vexing issues pertaining to the quantum ...
Sobolev spaces associated to the harmonic oscillator
Indian Academy of Sciences (India)
2Departamento de Matemática, Facultad de Ciencias, Universidad Autónoma de. Madrid, Spain. E-mail: bbongio@math.unl.edu.ar; joseluis.torrea@uam.es. MS received 27 September 2005. Abstract. We define the Hermite–Sobolev spaces naturally associated to the harmonic oscillator H = − + |x|2. Structural properties ...
Exponentially tapered Josephson flux-flow oscillator
DEFF Research Database (Denmark)
Benabdallah, A.; Caputo, J. G.; Scott, Alwyn C.
1996-01-01
We introduce an exponentially tapered Josephson flux-flow oscillator that is tuned by applying a bias current to the larger end of the junction. Numerical and analytical studies show that above a threshold level of bias current the static solution becomes unstable and gives rise to a train of flu...
Control of partial synchronization in chaotic oscillators
Indian Academy of Sciences (India)
2015-02-07
Feb 7, 2015 ... A design of coupling is proposed to control partial synchronization in two chaotic oscillators in a driver–response mode. ... Department of Mathematics, University of Technology and Management, Shillong 793 003, India; Central Instrumentation Division, CSIR-Indian Institute of Chemical Biology, Kolkata ...
CHAOTIC DUFFING TYPE OSCILLATOR WITH INERTIAL DAMPING
DEFF Research Database (Denmark)
Tamaševicius, Arunas; Mykolaitis, Gytis; Kirvaitis, Raimundas
2009-01-01
A novel Duffing-Holmes type autonomous chaotic oscillator is described. In comparison with the well-known non-autonomous Duffing-Holmes circuit it lacks the external periodic drive, but includes two extra linear feedback sub-circuits, namely a direct positive feedback loop, and an inertial negative...... feedback loop. SPICE simulation and hardware experimental results are presented....
Seasonality and mechanisms of tropical intraseasonal oscillations
Hazra, Abheera; Krishnamurthy, V.
2018-01-01
This study has compared the monsoon intraseasonal oscillation (MISO) during the boreal summer and Madden Julian Oscillation (MJO) during the boreal winter. Based on MISO and MJO in high-resolution three-dimensional diabatic heating, the possible mechanisms are discussed through observational analyses of dynamical and thermodynamical variables. The MISO and MJO are extracted as nonlinear oscillations during boreal summer and winter, respectively, by applying multi-channel singular spectrum analysis on daily anomalies of diabatic heating over the Indo-Pacific region. Lead and lag relations among moisture, temperature and surface fields relative to diabatic heating are analyzed to compare the mechanisms of MISO and MJO. While both the oscillations show eastward propagation, MISO has a strong northward propagation and MJO has a weak southward propagation as well. The analysis shows that MJO and MISO are essentially driven by the same mechanisms but with some difference in the meridional propagation. The westerly shear leads the diabatic heating, while the vorticity has weak correlation. Large-scale circulation creates positive moisture preconditioning before convection and negative moisture preconditioning before suppressed conditions. A positive lower level horizontal advection of temperature and upper level temperature tendencies lead the convective state while a negative lower level horizontal advection of temperature and upper level temperature tendencies lead the suppressed state. There is positive feedback from the SST to atmosphere. The difference in the meridional propagation of MISO and MJO is hypothesized to be because of the different differential heating meridionally during the two seasons.
Oscillating from Neurosecretion to Multitasking Dopamine Neurons
Directory of Open Access Journals (Sweden)
David R. Grattan
2016-04-01
Full Text Available In this issue of Cell Reports, Stagkourakis et al. (2016 report that oscillating hypothalamic TIDA neurons, previously thought to be simple neurosecretory neurons controlling pituitary prolactin secretion, control dopamine output via autoregulatory mechanisms and thus could potentially regulate other physiologically important hypothalamic neuronal circuits.
Pattern formation in arrays of chemical oscillators
Indian Academy of Sciences (India)
The spatiotemporal patterns obtained include clustering, mixed dynamics, inhomogeneous steady states and amplitude death. ... Amplitude death (AD) results in a homogeneous steady state, where all oscillators go to identical steady states ..... Barring the boundary cells, one observes near phase flip and near synchrony ...
Retinal oscillations carry visual information to cortex
Directory of Open Access Journals (Sweden)
Kilian Koepsell
2009-04-01
Full Text Available Thalamic relay cells fire action potentials that transmit information from retina to cortex. The amount of information that spike trains encode is usually estimated from the precision of spike timing with respect to the stimulus. Sensory input, however, is only one factor that influences neural activity. For example, intrinsic dynamics, such as oscillations of networks of neurons, also modulate firing pattern. Here, we asked if retinal oscillations might help to convey information to neurons downstream. Specifically, we made whole-cell recordings from relay cells to reveal retinal inputs (EPSPs and thalamic outputs (spikes and then analyzed these events with information theory. Our results show that thalamic spike trains operate as two multiplexed channels. One channel, which occupies a low frequency band (<30 Hz, is encoded by average firing rate with respect to the stimulus and carries information about local changes in the visual field over time. The other operates in the gamma frequency band (40-80 Hz and is encoded by spike timing relative to retinal oscillations. At times, the second channel conveyed even more information than the first. Because retinal oscillations involve extensive networks of ganglion cells, it is likely that the second channel transmits information about global features of the visual scene.
Assessing the quality of stochastic oscillations
Indian Academy of Sciences (India)
is small, and that no microscopic model will show oscillations if that parameter is large. The transition between these two regimes ... on the epidemiology of Hantavirus in wild rodent populations. This project, de- voted to ... certain sense and regimes in which one-individual changes are small, constitute a sensible limit of the ...
Neuronal Network Mechanisms of Gamma Oscillations
Viriyopase, A.
2017-01-01
Neuronal oscillations at various frequency bands play an important role in neuronal information processing. In this thesis, we mathematically and computationally investigated the properties of the gamma band (30-80 Hz) with different networks: a simplified network with two neurons, a large network
Magneto-elastic Oscillations and Magnetar QPOs
Stergioulas, N.; Gabler, M.; Cerdá-Durán, P.; Font, J. A.; Müller, E.
2012-07-01
The origin of the quasi-periodic oscillations (QPOs) observed in the giant flares of soft gamma-ray repeaters (SGRs) remains uncertain. Current models explore the idea that long-term quasi-periodic oscillations are trapped at the turning points of the continuum of torsional magneto-elastic oscillations in the magnetar's interior. After reviewing recent work in this field, we describe our latest efforts using two-dimensional, general-relativistic, magneto-hydrodynamical simulations, coupled to evolutions of shear waves in the solid crust, in order to explore the viability of this model when a purely dipolar magnetic field is assumed. We demonstrate the existence of three different regimes (a) B 1015 G, where magneto-elastic oscillations reach the surface and approach the behavior of purely Alfvén QPOs. Our results do not leave much room for a crustal-mode interpretation of observed QPOs in SGR giant flares, in the case of a purely dipolar magnetic field. On the other hand, the observed QPOs could originate from Alfvén-like, global, turning-point QPOs in models with dipolar magnetic field strengths in the narrow range of 5 × 1015 G ≤ B ≤ 1.4 × 1016 G. To agree with estimates for magnetic field strengths in known magnetars, a more complicated magnetic field structure or superfluidity of the neutrons and superconductivity of the protons should be taken into account.
Active Emulsions: Synchronization of Chemical Oscillators
Fraden, Seth
2012-02-01
We explore the dynamical behavior of emulsions consisting of nanoliter volume droplets of the oscillatory Belousov-Zhabotinsky (BZ) reaction separated by a continuous oil phase. Some of the aqueous BZ reactants partition into the oil leading to chemical coupling of the drops. We use microfluidics to vary the size, composition and topology of the drops in 1D and 2D. Addition of a light sensitive catalyst to the drops and illumination with a computer projector allows each drop to be individually perturbed. A variety of synchronous regimes are found that systematically vary with the coupling strength and whether coupling is dominated by activatory or inhibitory species. In 1D we observe in- and anti-phase oscillations, stationary Turing patterns in which drops stop oscillating, but form spatially periodic patterns of drops in the oxidized and reduced states, and more complex combinations of stationary and oscillatory drops. In 2D, the attractors are more complex and vary with network topology and coupling strength. For hexagonal lattices as a function of increasing coupling strength we observe right and left handed rotating oscillations, mixed oscillatory and Turing states and finally full Turing states. Reaction -- diffusion models based on a simplified description of the BZ chemistry and diffusion of messenger species reproduce a number of the experimental results. For a range of parameters, a simplified phase oscillator model provides an intuitive understanding of the complex synchronization patterns. [4pt] ``Coupled oscillations in a 1D emulsion of Belousov--Zhabotinsky droplets,'' Jorge Delgado, Ning Li, Marcin Leda, Hector O. Gonzalez-Ochoa, Seth Fraden and Irving R. Epstein, Soft Matter, 7, 3155 (2011).
Generalized Boltzmann formalism for oscillating neutrinos
Strack, P.; Burrows, A.
2005-05-01
In the standard approaches to neutrino transport in the simulation of core-collapse supernovas, one will often start from the classical Boltzmann equation for the neutrino’s spatial, temporal, and spectral evolution. For each neutrino species, and its antiparticle, the classical density in phase space, or the associated specific intensity, will be calculated as a function of time. The neutrino radiation is coupled to matter by source and sink terms on the “right-hand side” of the transport equation and together with the equations of hydrodynamics this set of coupled partial differential equations for classical densities describes, in principle, the evolution of core collapse and explosion. However, with the possibility of neutrino oscillations between species, a purely quantum-physical effect, how to generalize this set of Boltzmann equations for classical quantities to reflect oscillation physics has not been clear. To date, the formalisms developed have retained the character of quantum operator physics involving complex quantities and have not been suitable for easy incorporation into standard supernova codes. In this paper, we derive generalized Boltzmann equations for quasiclassical, real-valued phase-space densities that retain all the standard oscillation phenomenology, including the matter-enhanced resonant flavor conversion (Mikheev-Smirnov-Wolfenstein effect), neutrino self-interactions, and the interplay between decohering matter coupling and flavor oscillations. With this formalism, any code(s) that can now handle the solution of the classical Boltzmann or transport equation can easily be generalized to include neutrino oscillations in a quantum-physically consistent fashion.
A study of neutrino oscillations in MINOS
Energy Technology Data Exchange (ETDEWEB)
Raufer, Tobias Martin [Univ. College, Oxford (United Kingdom)
2007-01-01
MINOS is a long-baseline neutrino oscillations experiment located at Fermi National Accelerator Laboratory (FNAL), USA. It makes use of the NuMI neutrino beamline and two functionally identical detectors located at distances of ~1km and ~735km from the neutrino production target respectively. The Near Detector measures the composition and energy spectrum of the neutrino beam with high precision while the Far Detector looks for evidence of neutrino oscillations. This thesis presents work conducted in two distinct areas of the MINOS experiment: analysis of neutral current and charged current interactions. While charged current events are only sensitive to muon neutrino disappearance, neutral current events can be used to distinguish oscillations into sterile neutrinos from those involving only active neutrino species. A complete, preliminary neutral current study is performed on simulated data. This is followed by a more detailed investigation of neutral current neutrino interactions in the MINOS Near Detector. A procedure identifying neutral current interactions and rejecting backgrounds due to reconstruction failures is developed. Two distinct event classification methods are investigated. The selected neutral current events in the Near Detector are used to extract corrections to the neutral current cross-section in the MINOS Monte Carlo simulation as a function of energy. The resulting correction factors are consistent with unity. The main MINOS charged current neutrino disappearance analysis is described. We present the Monte Carlo tuning procedure, event selection, extrapolation from Near to Far Detector and fit for neutrino oscillations. Systematic errors on this measurement are evaluated and discussed in detail. The data are consistent with neutrino oscillations with the following parameters: 2.74 $+0.44\\atop{-0.26}$ x 10^{-3} eV^{2} and sin^{2}(2θ_{23}) > 0.87 at 68% confidence level.
Oscillations in atmospheric water above Switzerland
Directory of Open Access Journals (Sweden)
K. Hocke
2017-10-01
Full Text Available Cloud fraction (CF, integrated liquid water (ILW and integrated water vapour (IWV were continuously measured from 2004 to 2016 by the TROpospheric WAter RAdiometer (TROWARA in Bern, Switzerland. There are indications for interannual variations of CF and ILW. A spectral analysis shows that IWV is dominated by an annual oscillation, leading to an IWV maximum of 24 kg m−2 in July to August and a minimum of 8 kg m−2 in February. The seasonal behaviour of CF and ILW is composed by both the annual and the semiannual oscillation. However, the annual oscillation of CF has a maximum in December while the annual oscillation of ILW has a maximum in July. The semiannual oscillations of CF and ILW are strong from 2010 to 2014. The normalized power spectra of ILW and CF show statistically significant spectral components with periods of 76, 85, 97 and 150 days. We find a similarity between the power spectra of ILW and CF with those of zonal wind at 830 hPa (1.5 km above Bern. Particularly, the occurrence of higher harmonics in the CF and ILW spectra is possibly forced by the behaviour of the lower-tropospheric wind. The mean amplitude spectra of CF, ILW and IWV show increased short-term variability on timescales less than 40 days from spring to fall. We find a weekly cycle of CF and ILW from June to September with increased values on Saturday, Sunday and Monday.
MMIC Cavity Oscillator at 50 and 94 GHz Project
National Aeronautics and Space Administration — An innovative, ultra low noise, single chip cavity oscillator is proposed. The oscillator is fully integrated on standard MMIC process. It operates in the frequency...
Oscillations in critical shearing, application to fractures in glaciers
Directory of Open Access Journals (Sweden)
A. Pralong
2006-01-01
Full Text Available Many evidences of oscillations accompanying the acceleration of critical systems have been reported. These oscillations are usually related to discrete scale invariance properties of the systems and exhibit a logarithmic periodicity. In this paper we propose another explanation for these oscillations in the case of shearing fracture. Using a continuum damage model, we show that oscillations emerge from the anisotropic properties of the cracks in the shearing fracture zone. These oscillations no longer exhibit a logarithmic but rather a power-law periodicity. The power-periodic oscillation is a more general formulation. Its reduces to a log-periodic oscillation when the exponent of the power-law equals one. We apply this model to fit the measured displacements of unstable ice masses of hanging glaciers for which data are available. Results show that power-periodic oscillations adequately fit the observations.
Kappa-effect and brightness oscillations of stars
Zhugzhda, Y. D.; Roth, M.; Herzberg, W.
2012-12-01
In this paper the theory of visibility and darkening functions for the brightness oscillations of stars is outlined. For this the non-grey approximation is used and the effect of opacity disturbances on stellar brightness oscillations is explored for different types of stars. An explanation of the Procyon paradox is proposed. Special features of the brightness oscillations are discussed. The effect of opacity fluctuations on the damping of p-mode oscillations is considered. Furthermore, the photospheric kappa-mechanism is discussed.
Mixed Mode Oscillations due to the Generalized Canard Phenomenon
DEFF Research Database (Denmark)
Brøns, Morten; Krupa, Martin; Wechselberger, Martin
2006-01-01
Mixed mode oscillations combine features of small oscillations and large oscillations of relaxation type. We describe a mechanism for mixed mode oscillations based on the presence of canard solutions, which are trajectories passing from a stable to an unstable slow manifold. An important ingredient...... on mixed mode periodic orbits with Farey sequences of the form 1s. We also show how to generalize the context of one fast variable to an arbitrary number of fast variables....
Phase patterns of coupled oscillators with application to wireless communication
Energy Technology Data Exchange (ETDEWEB)
Arenas, A.
2008-01-02
Here we study the plausibility of a phase oscillators dynamical model for TDMA in wireless communication networks. We show that emerging patterns of phase locking states between oscillators can eventually oscillate in a round-robin schedule, in a similar way to models of pulse coupled oscillators designed to this end. The results open the door for new communication protocols in a continuous interacting networks of wireless communication devices.
Driven damped harmonic oscillator resonance with an Arduino
Goncalves, A. M. B.; Cena, C. R.; Bozano, D. F.
2017-07-01
In this paper we propose a simple experimental apparatus that can be used to show quantitative and qualitative results of resonance in a driven damped harmonic oscillator. The driven oscillation is made by a servo motor, and the oscillation amplitude is measured by an ultrasonic position sensor. Both are controlled by an Arduino board. The frequency of free oscillation measured was campatible with the resonance frequency that was measured.
Noise Exposure in TKA Surgery; Oscillating Tip Saw Systems vs Oscillating Blade Saw Systems.
Peters, Michiel P; Feczko, Peter Z; Tsang, Karel; van Rietbergen, Bert; Arts, Jacobus J; Emans, Peter J
2016-12-01
Historically it has been suggested that noise-induced hearing loss (NIHL) affects approximately 50% of the orthopedic surgery personnel. This noise may be partially caused by the use of powered saw systems that are used to make the bone cuts. The first goal was to quantify and compare the noise emission of these different saw systems during total knee arthroplasty (TKA) surgery. A second goal was to estimate the occupational NIHL risk for the orthopedic surgery personnel in TKA surgery by quantifying the total daily noise emission spectrum during TKA surgery and to compare this to the Dutch Occupational Health Organization guidelines. A conventional sagittal oscillating blade system with a full oscillating blade and 2 newer oscillating tip saw systems (handpiece and blade) were compared. Noise level measurements during TKA surgery were performed during cutting and hammering, additionally surgery noise profiles were made. The noise level was significantly lower for the oscillating tip saw systems compared to the conventional saw system, but all were in a range that can cause NIHL. The conventional system handpiece produced a considerable higher noise level compared to oscillating tip handpiece. NIHL is an underestimated problem in the orthopedic surgery. Solutions for decreasing the risk of hearing loss should be considered. The use of oscillating tip saw systems have a reduced noise emission in comparison with the conventional saw system. The use of these newer systems might be a first step in decreasing hearing loss among the orthopedic surgery personnel. Copyright © 2016 Elsevier Inc. All rights reserved.
Direct observation of surface-state thermal oscillations in SmB6 oscillators
Casas, Brian; Stern, Alex; Efimkin, Dmitry K.; Fisk, Zachary; Xia, Jing
2018-01-01
SmB6 is a mixed valence Kondo insulator that exhibits a sharp increase in resistance following an activated behavior that levels off and saturates below 4 K. This behavior can be explained by the proposal of SmB6 representing a new state of matter, a topological Kondo insulator, in which a Kondo gap is developed, and topologically protected surface conduction dominates low-temperature transport. Exploiting its nonlinear dynamics, a tunable SmB6 oscillator device was recently demonstrated, where a small dc current generates large oscillating voltages at frequencies from a few Hz to hundreds of MHz. This behavior was explained by a theoretical model describing the thermal and electronic dynamics of coupled surface and bulk states. However, a crucial aspect of this model, the predicted temperature oscillation in the surface state, has not been experimentally observed to date. This is largely due to the technical difficulty of detecting an oscillating temperature of the very thin surface state. Here we report direct measurements of the time-dependent surface-state temperature in SmB6 with a RuO2 microthermometer. Our results agree quantitatively with the theoretically simulated temperature waveform, and hence support the validity of the oscillator model, which will provide accurate theoretical guidance for developing future SmB6 oscillators at higher frequencies.
Shortest loops are pacemakers in random networks of electrically coupled axons
Directory of Open Access Journals (Sweden)
Nikita eVladimirov
2012-04-01
Full Text Available High-frequency oscillations (HFOs are an important part of brain activity in health and disease. However, their origins remain obscure and controversial. One possible mechanism depends on the presence of sparsely distributed gap junctions that electrically couple the axons of principal cells. A plexus of electrically coupled axons is modeled as a random network with bidirectional connections between its nodes. Under certain conditions the network can demonstrate one of two types of oscillatory activity. Type I oscillations (100-200 Hz are predicted to be caused by spontaneously spiking axons in a network with strong (high-conductance gap junctions. Type II oscillations (200-300 Hz require no spontaneous spiking and relatively weak (low-conductance gap junctions, across which spike propagation failures occur. The type II oscillations are reentrant and self-sustained. Here we examine what determines the frequency of type II oscillations. Using simulations we show that the distribution of loop lengths is the key factor for determining frequency in type II network oscillations. We first analyze spike failure between two electrically coupled cells using a model of anatomically reconstructed CA1 pyramidal neuron. Then network oscillations are studied by a cellular automaton model with random network connectivity, in which we control loop statistics. We show that oscillation periods can be predicted from the network's loop statistics. The shortest loop, around which a spike can travel, is the most likely pacemaker candidate.The principle of one loop as a pacemaker is remarkable, because random networks contain a large number of loops juxtaposed and superimposed, and their number rapidly grows with network size. This principle allows us to predict the frequency of oscillations from network connectivity and visa versa. We finally propose that type I oscillations may correspond to ripples, while type II oscillations correspond to so-called fast ripples.
On quantum harmonic oscillator being subjected to absolute ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 88; Issue 1. On quantum ... In a quantum harmonic oscillator (QHO), the energy of the oscillator increases with increased frequency. ... This new function, which corresponds to new sets of particles, has scope to raise the quantum oscillator energy (QOE) up to infinity.
Quantum dissipative effect of one dimension coupled anharmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Sulaiman, A. [Badan Pengkajian dan Penerapan Teknologi, BPPT Bld. II (19thfloor), Jl. M.H. Thamrin 8, Jakarta 10340 (Indonesia); Indonesia Center for Theoretical and Mathematical Physics (ICTMP), Jl. Ganesha 10, Bandung 40132 (Indonesia); Zen, Freddy P. [Theoretical Physics Laboratory (THEPI), Department of Physics, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Indonesia Center for Theoretical and Mathematical Physics (ICTMP), Jl. Ganesha 10, Bandung 40132 (Indonesia)
2015-04-16
Quantum dissipative effect of one dimension coupled anharmonic oscillator is investigated. The systems are two coupled harmonic oscillator with the different masses. The dissipative effect is studied based on the quantum state diffusion formalism. The result show that the anharmonic effect increase the amplitude but the lifetime of the oscillation depend on the damping coefficient and do not depend on the temperature.
Towards minimum achievable phase noise of relaxation oscillators
Geraedts, P.F.J.; van Tuijl, Adrianus Johannes Maria; Klumperink, Eric A.M.; Wienk, Gerhardus J.M.; Nauta, Bram
2013-01-01
A relaxation oscillator design is described, which has a phase noise rivaling ring oscillators, while also featuring linear frequency tuning. We show that the comparator in a relaxation-oscillator loop can be prevented from contributing to 1/f2 colored phase noise and degrading control linearity.
New solutions of stokes problem for an oscillating plate using ...
African Journals Online (AJOL)
New solutions of stokes problem for an oscillating plate using Laplace transform. Ehsan Ellahi Ashraf, Muhammad R Mohyuddin. Abstract. An exact solution of the flow of a Newtonian fluid on a porous plate is obtained when the plate at y = 0 is oscillating with the amplitude β and oscillating frequency ω with the assumption ...
The designer's guide to high-purity oscillators
Hegazi, Emad; Abidi, Asad
2006-01-01
Presents a comprehensive theory and design methodology for the design of LC CMOS oscillators used in every wireless transmission system. This book introduces the subject of phase noise and oscillators from the very first principles, and attempts to carry the reader to a very intuitive circuit-driven theory of phase noise in LC oscillators.
Shape oscillation of bubbles in the acoustic field
Matsumoto, Keishi; Ueno, Ichiro
2009-01-01
The authors introduce dynamics of multiple air bubbles exposed to ultrasonic wave while ascending in water in the present fluid dynamics video. The authors pay attention to the shape oscillation and the transition from the volume to the shape oscillations of the bubble. Correlation between the bubble size and the mechanism of the excitation of the shape oscillation is introduced.
Oscillations in deviating difference equations using an iterative technique
Directory of Open Access Journals (Sweden)
George E Chatzarakis
2017-07-01
Full Text Available Abstract The paper deals with the oscillation of the first-order linear difference equation with deviating argument and nonnegative coefficients. New sufficient oscillation conditions, involving limsup, are given, which essentially improve all known results, based on an iterative technique. We illustrate the results and the improvement over other known oscillation criteria by examples, numerically solved in Matlab.
Phase-frequency calibration of a sine wave oscillator using ...
African Journals Online (AJOL)
A method of measuring phase changes within the positive feedback loop of a sine wave oscillator without terminating the oscillations is presented. This involves the use of a reference network, outside the loop, which is an exact replica of the positive feedback network of the oscillator. Such phase changes produce new ...
ajansen; kwhitefoot; panteltje1; edprochak; sudhakar, the
2014-07-01
In reply to the physicsworld.com news story “How to make a quantum random-number generator from a mobile phone” (16 May, http://ow.ly/xFiYc, see also p5), which describes a way of delivering random numbers by counting the number of photons that impinge on each of the individual pixels in the camera of a Nokia N9 smartphone.
Functional role of frontal alpha oscillations in creativity.
Lustenberger, Caroline; Boyle, Michael R; Foulser, A Alban; Mellin, Juliann M; Fröhlich, Flavio
2015-06-01
Creativity, the ability to produce innovative ideas, is a key higher-order cognitive function that is poorly understood. At the level of macroscopic cortical network dynamics, recent electroencephalography (EEG) data suggests that cortical oscillations in the alpha frequency band (8-12 Hz) are correlated with creative thinking. However, whether alpha oscillations play a functional role in creativity has remained unknown. Here we show that creativity is increased by enhancing alpha power using 10 Hz transcranial alternating current stimulation (10 Hz-tACS) of the frontal cortex. In a study of 20 healthy participants with a randomized, balanced cross-over design, we found a significant improvement of 7.4% in the Creativity Index measured by the Torrance Test of Creative Thinking (TTCT), a comprehensive and most frequently used assay of creative potential and strengths. In a second similar study with 20 subjects, 40 Hz-tACS was used instead of 10 Hz-tACS to rule out a general "electrical stimulation" effect. No significant change in the Creativity Index was found for such frontal 40 Hz stimulation. Our results suggest that alpha activity in frontal brain areas is selectively involved in creativity; this enhancement represents the first demonstration of specific neuronal dynamics that drive creativity and can be modulated by non-invasive brain stimulation. Our findings agree with the model that alpha recruitment increases with internal processing demands and is involved in inhibitory top-down control, which is an important requirement for creative ideation. Copyright © 2015 Elsevier Ltd. All rights reserved.
Automated Marx’s Composite Oscillator Method
Tateno, Hiroto; Taniguchi, Hideaki
1980-01-01
Marx’s composite oscillator method has been successfully automated for measuring internal friction and Young’s modulus. The apparatus automatically finds the mechanical resonant frequency of the composite oscillator and keeps the strain amplitude constant, so that internal friction and the modulus can easily be measured and directly recorded on an X-t recorder. This device enables us to observe continuously the time dependence of the pinning and unpinning processes of dislocation by point defects. The error in strain amplitude is suppressed to within ±0.1%, while the internal friction value changes by 2 orders of magnitude. The operation of this system has been analyzed by automatic control theory, and the theoretical results are in good agreement with the experiment results. The analysis and the application of this method are presented here together with some experimental results.
Asymptotic representation of relaxation oscillations in lasers
Grigorieva, Elena V
2017-01-01
In this book we analyze relaxation oscillations in models of lasers with nonlinear elements controlling light dynamics. The models are based on rate equations taking into account periodic modulation of parameters, optoelectronic delayed feedback, mutual coupling between lasers, intermodal interaction and other factors. With the aim to study relaxation oscillations we present the special asymptotic method of integration for ordinary differential equations and differential-difference equations. As a result, they are reduced to discrete maps. Analyzing the maps we describe analytically such nonlinear phenomena in lasers as multistability of large-amplitude relaxation cycles, bifurcations of cycles, controlled switching of regimes, phase synchronization in an ensemble of coupled systems and others. The book can be fruitful for students and technicians in nonlinear laser dynamics and in differential equations.
Improving the precision of noisy oscillators
Moehlis, Jeff
2014-04-01
We consider how the period of an oscillator is affected by white noise, with special attention given to the cases of additive noise and parameter fluctuations. Our treatment is based upon the concepts of isochrons, which extend the notion of the phase of a stable periodic orbit to the basin of attraction of the periodic orbit, and phase response curves, which can be used to understand the geometry of isochrons near the periodic orbit. This includes a derivation of the leading-order effect of noise on the statistics of an oscillator’s period. Several examples are considered in detail, which illustrate the use and validity of the theory, and demonstrate how to improve a noisy oscillator’s precision by appropriately tuning system parameters or operating away from a bifurcation point. It is also shown that appropriately timed impulsive kicks can give further improvements to oscillator precision.
Self-oscillating resonant power converter
DEFF Research Database (Denmark)
2014-01-01
The present invention relates to resonant power converters and inverters comprising a self-oscillating feedback loop coupled from a switch output to a control input of a switching network comprising one or more semiconductor switches. The self-oscillating feedback loop sets a switching frequency...... of the power converter and comprises a first intrinsic switch capacitance coupled between a switch output and a control input of the switching network and a first inductor. The first inductor is coupled in-between a first bias voltage source and the control input of the switching network and has...... a substantially fixed inductance. The first bias voltage source is configured to generate an adjustable bias voltage applied to the first inductor. The output voltage of the power converter is controlled in a flexible and rapid manner by controlling the adjustable bias voltage....
Neutrino Oscillation Experiments at Nuclear Reactors
Gratta, Giorgio
2000-01-01
In this paper I give an overview of the status of neutrino oscillation experiments performed using nuclear reactors as sources of neutrinos. I review the present generation of experiments (Chooz and Palo Verde) with baselines of about 1 km as well as the next generation that will search for oscillations with a baseline of about 100 km. While the present detectors provide essential input towards the understanding of the atmospheric neutrino anomaly, in the future, the KamLAND reactor experiment represents our best opportunity to study very small mass neutrino mixing in laboratory conditions. In addition KamLAND with its very large fiducial mass and low energy threshold, will also be sensitive to a broad range of different physics.
DAMPING OF SUBSYNCHRONOUS MODES OF OSCILLATIONS
Directory of Open Access Journals (Sweden)
JAGADEESH PASUPULETI
2006-06-01
Full Text Available The IEEE bench mark model 2 series compensated system is considered for analysis. It consists of single machine supplying power to infinite bus through two parallel lines one of which is series compensated. The mechanical system considered consists of six mass, viz, high pressure turbine, intermediate pressure turbine, two low pressure turbines, generator and an exciter. The excitation system considered is IEEE type 1 with saturation. The auxiliary controls considered to damp the unstable subsynchronous modes of oscillations are Power System Stabilizer (PSS and Static var Compensator (SVC. The different cases of power system stabilizer and reactive power controls are adapted to study the effectiveness of damping these unstable subsynchronous modes of oscillations.
Parametric excitation of a linear oscillator
Butikov, Eugene I.
2004-07-01
The phenomenon of parametric resonance is explained and investigated both analytically and with the help of a computer simulation. Parametric excitation is studied for the example of the rotary oscillations of a simple linear system—mechanical torsion spring pendulum excited by periodic variations of its moment of inertia. Conditions and characteristics of parametric resonance and regeneration are found and discussed in detail. Ranges of frequencies within which parametric excitation is possible are determined. Stationary oscillations at the boundaries of these ranges are investigated. The simulation experiments aid greatly an understanding of basic principles and peculiarities of parametric excitation and complement the analytical study of the subject in a manner that is mutually reinforcing.
Parametric excitation of a linear oscillator
Energy Technology Data Exchange (ETDEWEB)
Butikov, Eugene I [St Petersburg State University, St Petersburg (Russian Federation)
2004-07-16
The phenomenon of parametric resonance is explained and investigated both analytically and with the help of a computer simulation. Parametric excitation is studied for the example of the rotary oscillations of a simple linear system-mechanical torsion spring pendulum excited by periodic variations of its moment of inertia. Conditions and characteristics of parametric resonance and regeneration are found and discussed in detail. Ranges of frequencies within which parametric excitation is possible are determined. Stationary oscillations at the boundaries of these ranges are investigated. The simulation experiments aid greatly an understanding of basic principles and peculiarities of parametric excitation and complement the analytical study of the subject in a manner that is mutually reinforcing.
Amplitude dependent shift of betatron oscillation center
Directory of Open Access Journals (Sweden)
Yoshihiko Shoji
2014-06-01
Full Text Available We have analytically calculated and measured the amplitude-dependent shift of the betatron oscillation center at the electron storage ring, NewSUBARU. The shift is due to nonzero average horizontal deflections at the normal sextupole magnets. The shifted center forms a displaced closed orbit and is measured by a closed orbit distortion measurement system, although no single electron runs on this orbit. The measured shifts by betatron oscillations agreed with the theoretical calculation except the variation of data points, which did not obey the ring symmetry. Additional measurements, whose results included the effect of the circumference shift, experimentally proved the amplitude dependent circumference shift for the first time. We also discuss some applications of the shift, which has never been previously analyzed.
Bessel beams with spatial oscillating polarization
Fu, Shiyao; Zhang, Shikun; Gao, Chunqing
2016-01-01
Bessel beams are widely used in optical metrology mainly because of their large Rayleigh range (focal length). Radial/azimuthal polarization of such beams is of interest in the fields of material processing, plasma absorption or communication. In this paper an experimental set-up is presented, which generates a Bessel-type vector beam with a spatial polarization, oscillating along the optical axis, when propagating in free space. A first holographic axicon (HA) HA1 produces a normal, linearly polarized Bessel beam, which by a second HA2 is converted into the spatial oscillating polarized beam. The theory is briefly discussed, the set-up and the experimental results are presented in detail. PMID:27488174
Singular Isotonic Oscillator, Supersymmetry and Superintegrability
Directory of Open Access Journals (Sweden)
Ian Marquette
2012-09-01
Full Text Available In the case of a one-dimensional nonsingular Hamiltonian H and a singular supersymmetric partner H_a, the Darboux and factorization relations of supersymmetric quantum mechanics can be only formal relations. It was shown how we can construct an adequate partner by using infinite barriers placed where are located the singularities on the real axis and recover isospectrality. This method was applied to superpartners of the harmonic oscillator with one singularity. In this paper, we apply this method to the singular isotonic oscillator with two singularities on the real axis. We also applied these results to four 2D superintegrable systems with second and third-order integrals of motion obtained by Gravel for which polynomial algebras approach does not allow to obtain the energy spectrum of square integrable wavefunctions. We obtain solutions involving parabolic cylinder functions.
Relic neutrino decoupling including flavour oscillations
Energy Technology Data Exchange (ETDEWEB)
Mangano, Gianpiero [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II and INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Naples (Italy); Department of Physics, Syracuse University, Syracuse, NY 13244-1130 (United States); Miele, Gennaro [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II and INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Naples (Italy); Pastor, Sergio [Instituto de Fisica Corpuscular (CSIC-Universitat de Valencia), Ed. Institutos de Investigacion, Apdo. 22085, E-46071 Valencia (Spain)]. E-mail: pastor@ific.uv.es; Pinto, Teguayco [Instituto de Fisica Corpuscular (CSIC-Universitat de Valencia), Ed. Institutos de Investigacion, Apdo. 22085, E-46071 Valencia (Spain); Pisanti, Ofelia [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II and INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Naples (Italy); Serpico, Pasquale D. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, D-80805 Munich (Germany)
2005-11-21
In the early universe, neutrinos are slightly coupled when electron-positron pairs annihilate transferring their entropy to photons. This process originates non-thermal distortions on the neutrino spectra which depend on neutrino flavour, larger for {nu}{sub e} than for {nu}{sub {mu}} or {nu}{sub {tau}}. We study the effect of three-neutrino flavour oscillations on the process of neutrino decoupling by solving the momentum-dependent kinetic equations for the neutrino spectra. We find that oscillations do not essentially modify the total change in the neutrino energy density, giving N{sub eff}=3.046 in terms of the effective number of neutrinos, while the small effect over the production of primordial {sup 4}He is increased by O(20%), up to 2.1x10{sup -4}. These results are stable within the presently favoured region of neutrino mixing parameters.
Future neutrino oscillation physics in Japan
Energy Technology Data Exchange (ETDEWEB)
Kajita, Takaaki [Research Center for Cosmic Neutrinos, Institute for Cosmic Ray Research, Univ. of Tokyo, Kashiwa-no-ha 5-1-5, Kashiwa, Chiba 277-8582 (Japan)
2007-06-15
T2K is the next generation neutrino oscillation experiment. It will start in 2009. The main goals are the discovery of non-zero {theta}{sub 13} and precise measurements of sin{sup 2}2{theta}{sub 23} and {delta}m{sub 23}{sup 2}. If non-zero {theta}{sub 13} is observed, T2K hopes to proceed to the next phase. With two identical detectors placed in Kamioka and Korea for the J-PARC neutrino beam, it will be possible to determine the CP violation phase and the neutrino mass hierarchy. In addition, this setup can determine the octant of {theta}{sub 23} by the observation of solar oscillation effect.
Experimental observation of Rabi oscillations in photonic lattices.
Shandarova, Ksenia; Rüter, Christian E; Kip, Detlef; Makris, Konstantinos G; Christodoulides, Demetrios N; Peleg, Or; Segev, Mordechai
2009-03-27
We demonstrate spatial Rabi oscillations in optical waveguide arrays. Adiabatic transitions between extended Floquet-Bloch modes associated with different bands are stimulated by periodic modulation of the photonic lattice in the propagation direction. When the stimulating modulation also carries transverse momentum, the transition becomes indirect, equivalent to phonon-assisted Rabi oscillations. In solid state physics such indirect Rabi oscillations necessitate coherent phonons and hence they have never been observed. Our experiments suggest that phonon-assisted Rabi oscillations are observable also with Bose-Einstein condensates, as well as with other wave systems-where coherence can be maintained for at least one period of the Rabi oscillation.
Entanglement of higher-derivative oscillators in holographic systems
Energy Technology Data Exchange (ETDEWEB)
Dimov, Hristo, E-mail: h_dimov@phys.uni-sofia.bg [Department of Physics, Sofia University, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Mladenov, Stefan, E-mail: smladenov@phys.uni-sofia.bg [Department of Physics, Sofia University, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Rashkov, Radoslav C., E-mail: rash@phys.uni-sofia.bg [Department of Physics, Sofia University, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstr. 8–10, 1040 Vienna (Austria); Vetsov, Tsvetan, E-mail: vetsov@phys.uni-sofia.bg [Department of Physics, Sofia University, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria)
2017-05-15
We study the quantum entanglement of coupled Pais–Uhlenbeck oscillators using the formalism of thermo-field dynamics. The entanglement entropy is computed for the specific cases of two and a ring of N coupled Pais–Uhlenbeck oscillators of fourth order. It is shown that the entanglement entropy depends on the temperatures, frequencies and coupling parameters of the different degrees of freedom corresponding to harmonic oscillators. We also make remarks on the appearance of instabilities of higher-derivative oscillators in the context of AdS/CFT correspondence. Finally, we advert to the information geometry theory by calculating the Fisher information metric for the considered system of coupled oscillators.
Colpitts Chaotic Oscillator Coupling with a Generalized Memristor
Directory of Open Access Journals (Sweden)
Ling Lu
2015-01-01
Full Text Available By introducing a generalized memristor into a fourth-order Colpitts chaotic oscillator, a new memristive Colpitts chaotic oscillator is proposed in this paper. The generalized memristor is equivalent to a diode bridge cascaded with a first-order parallel RC filter. Chaotic attractors of the oscillator are numerically revealed from the mathematical model and experimentally captured from the physical circuit. The dynamics of the memristive Colpitts chaotic oscillator is investigated both theoretically and numerically, from which it can be found that the oscillator has a unique equilibrium point and displays complex nonlinear phenomena.
Scaling effect of spin-torque nano-oscillators
Directory of Open Access Journals (Sweden)
Xiaohui Chao
2017-05-01
Full Text Available We have investigated the impact of device size on the characteristics of spin-torque nano-oscillators by studying the frequency and linewidth of the oscillator as a function of current density utilizing micromagnetic simulations at room temperature. Upon reduction of the device size from 40 down to 10 nm, thermal noise flattens the frequency and linewidth trends with current density and lowers the threshold current density of the oscillation. The magnetization vector trajectories reveal that irregular oscillations exist in smaller devices. Our findings suggest that a 20 × 20 nm2 spin-torque oscillator could be a viable candidate for a magnetic read sensor.
Spice Modeling of the Vilnius Chaotic Oscillator
Peters, Randall D.
2005-01-01
``A simple chaotic oscillator for educational purposes'' was recently described in the literature [1]. In addition to their hardware description, the authors of this paper generated a bifurcation diagram from the model equations presented in their paper. In the present treatment of their circuit the `simulation program for integrated circuit engineering' (Spice) has been used to generate some insightful graphs that were not shown by the Lithuania group.
High frequency pressure oscillator for microcryocoolers
Vanapalli, Srinivas; ter Brake, Hermanus J.M.; Jansen, Henricus V.; Zhao, Yiping; Holland, Herman J.; Burger, Johannes Faas; Elwenspoek, Michael Curt
2008-01-01
Microminiature pulse tube cryocoolers should operate at a frequency of an order higher than the conventional macro ones because the pulse tube cryocooler operating frequency scales inversely with the square of the pulse tube diameter. In this paper, the design and experiments of a high frequency pressure oscillator is presented with the aim to power a micropulse tube cryocooler operating between 300 and 80 K, delivering a cooling power of 10 mW. Piezoelectric actuators operate efficiently at ...
Atomic Oscillator Strengths In The Vacuum Ultraviolet
Nave, Gillian; Sansonetti, C. J.; Szabo, C. I.
2008-05-01
Transitionsin singly-ionized and doubly-ionized iron-group elements give rise to prominent emission lines from a wide variety of astrophysical objects. Although the database of experimental oscillator strengths of Fe II has also been greatly extended by the FERRUM project, few experimental oscillator strengths are available in the region below 1600 Å, where many levels that give rise to emission lines at longer wavelengths have their dominant decays. The established way to measure accurate oscillator strengths for atomic lines combines the measurement of a lifetime of an upper energy level with a separate measurement of the branching fractions of all the lines emitted from that level. This technique relies on being able to observe all the spectral lines emitted by the upper level, which range down to Ly-α or below for many fluorescence lines. We have developed techniques to measure branching fractions in the vacuum ultraviolet using our 10.7-m normal incidence grating spectrograph. For this we use phosphor image plates as replacements for the photographic plates previously used on this instrument. Image plates are sensitive to wavelengths from the X-ray region to 2200 Å, and have a linear intensity response with a dynamic range of at least 10000. We have recorded spectra of iron-neon hollow cathode and Penning discharges, using a deuterium standard lamp for radiometric calibration. We will present the first measurements of oscillator strengths using this technique. We are also investigating methods of radiometric calibration below 1150 Å using hollow cathode standard lamps. This will enable us to measure branching ratios down to 800 Å or below. This work is partially funded by NASA under the inter-agency agreement W-10,255.
Microgeometrical cavitation in oscillating slider contacts
Wietzel, U.
1994-04-01
This paper deals with microgeometrically-determined cavitation in oscillating slider bearings. After explaining the difference in the origin of cavitation in journal and linear bearings, the theoretical idea of a computer simulation program on the basis of a combined microhydryodynamic/solid-solid-contact approach is introduced. With the help of this program, slider surface geometry, inertia effects, lubricant properties, normal load, and lubricant film temperatures were found as parameters of microcavitation.
Dynamics of microcapsules in oscillating shear flow
Zhao, Mengye; Bagchi, Prosenjit
2011-11-01
We present a three-dimensional numerical study on the dynamics of deformable capsules in sinusoidally oscillating shear flow. We consider capsules of spherical and oblate spheroid resting shapes. For spherical resting shapes, we find an identical deformation response during positive and negative vorticities. However, the deformation response becomes unequal and shows complex behavior for nonspherical resting shapes. The average elongation is higher in the retarding phase of the shear flow than in the accelerating phase. Primarily two types of dynamics are observed for nonspherical shapes: a clockwise/counter-clockwise swinging motion in response to the altering flow direction that occurs at both high and low values of shear rate amplitudes, and a continuous/unidirectional tumbling motion that occurs at intermediate values. The unidirectional tumbling motion occurs despite the fact that the time-average vorticity is zero. Such a tumbling motion is accompanied by a continuous tank-treading motion of the membrane in the opposite direction. We obtain phase diagram that shows existence of two critical shear rates and two oscillation frequencies. The unidirectional tumbling motion occurs in the intermediate range, and the clockwise/counter-clockwise swinging motion occurs otherwise. We also find that the dynamics is highly sensitive to the initial condition. A swinging is generally observed when the capsule is released aligned with the extensional or compressional axis of the shear flow, and a tumbling is observed otherwise. These results suggest the possibility of chaotic behavior of cells in time-dependent flows. We provide explanations of such complex dynamics by analyzing the coupling between the shape and angular oscillation and the imposed flow oscillation.
Quantum state transfer via Bloch oscillations
Tamascelli, Dario; Olivares, Stefano; Rossotti, Stefano; Osellame, Roberto; Paris, Matteo G. A.
2016-01-01
The realization of reliable quantum channels, able to transfer a quantum state with high fidelity, is a fundamental step in the construction of scalable quantum devices. In this paper we describe a transmission scheme based on the genuinely quantum effect known as Bloch oscillations. The proposed protocol makes it possible to carry a quantum state over different distances with a minimal engineering of the transmission medium and can be implemented and verified on current quantum technology hardware. PMID:27189630
Oscillations of a string with concentrated masses
Energy Technology Data Exchange (ETDEWEB)
Gomez, B J [Instituto de Fisica Rosario (CONICET-UNR), Bv. 27 de Febrero 210 Bis, 2000 Rosario (Argentina); Repetto, C E [Instituto de Fisica Rosario (CONICET-UNR), Bv. 27 de Febrero 210 Bis, 2000 Rosario (Argentina); Stia, C R [Instituto de Fisica Rosario (CONICET-UNR), Bv. 27 de Febrero 210 Bis, 2000 Rosario (Argentina); Welti, R [Dto. de Fisica, Esc. de Formacion Basica, Facultad de Ciencias Exactas, IngenierIa y Agrimensura, Universidad Nacional de Rosario, Av. Pellegrini 250, 2000 Rosario (Argentina)
2007-09-15
In this work, the oscillations of a homogeneous string fixed at both ends, and loaded with a finite number of masses, are studied. Through a simple device, the cases with one and two concentrated masses are analysed in detail. The normal modes are observed and the corresponding frequencies are recorded. The experimental results and the solutions of the wave equation that satisfy suitable boundary conditions are compared. The theoretical and experimental results are in very good agreement.
Using Oscillating Sounds to Manipulate Sleep Spindles.
Antony, James W; Paller, Ken A
2017-03-01
EEG oscillations known as sleep spindles have been linked with various aspects of cognition, but the specific functions they signal remain controversial. Two types of EEG sleep spindles have been distinguished: slow spindles at 11-13.5 Hz and fast spindles at 13.5-16 Hz. Slow spindles exhibit a frontal scalp topography, whereas fast spindles exhibit a posterior scalp topography and have been preferentially linked with memory consolidation during sleep. To advance understanding beyond that provided from correlative studies of spindles, we aimed to develop a new method to systematically manipulate spindles. We presented repeating bursts of oscillating white noise to people during a 90-min afternoon nap. During stage 2 and slow-wave sleep, oscillations were embedded within contiguous 10-s stimulation intervals, each comprising 2 s of white noise amplitude modulated at 12 Hz (targeting slow spindles), 15 Hz (targeting fast spindles), or 50 Hz followed by 8 s of constant white noise. During oscillating stimulation compared to constant stimulation, parietal EEG recordings showed more slow spindles in the 12-Hz condition, more fast spindles in the 15-Hz condition, and no change in the 50-Hz control condition. These effects were topographically selective, and were absent in frontopolar EEG recordings, where slow spindle density was highest. Spindles during stimulation were similar to spontaneous spindles in standard physiological features, including duration and scalp distribution. These results define a new method to selectively and noninvasively manipulate spindles through acoustic resonance, while also providing new evidence for functional distinctions between the 2 types of EEG spindles.
Aligning Plasma-Arc Welding Oscillations
Norris, Jeff; Fairley, Mike
1989-01-01
Tool aids in alignment of oscillator probe on variable-polarity plasma-arc welding torch. Probe magnetically pulls arc from side to side as it moves along joint. Tensile strength of joint depends on alignment of weld bead and on alignment of probe. Operator installs new tool on front of torch body, levels it with built-in bubble glass, inserts probe in slot on tool, and locks probe in place. Procedure faster and easier and resulting alignment more accurate and repeatable.
Multidecadal oscillations in rainfall and hydrological extremes
Willems, Patrick
2013-01-01
Many studies have anticipated a worldwide increase in the frequency and intensity of precipitation extremes and floods since the last decade(s). Natural variability by climate oscillations partly determines the observed evolution of precipitation extremes. Based on a technique for the identification and analysis of changes in extreme quantiles, it is shown that hydrological extremes have oscillatory behaviour at multidecadal time scales. Results are based on nearly independent extremes extrac...
High frequency pressure oscillator for microcryocoolers
Vanapalli, S.; ter Brake, H. J. M.; Jansen, H. V.; Zhao, Y.; Holland, H. J.; Burger, J. F.; Elwenspoek, M. C.
2008-04-01
Microminiature pulse tube cryocoolers should operate at a frequency of an order higher than the conventional macro ones because the pulse tube cryocooler operating frequency scales inversely with the square of the pulse tube diameter. In this paper, the design and experiments of a high frequency pressure oscillator is presented with the aim to power a micropulse tube cryocooler operating between 300 and 80K, delivering a cooling power of 10mW. Piezoelectric actuators operate efficiently at high frequencies and have high power density making them good candidates as drivers for high frequency pressure oscillator. The pressure oscillator described in this work consists of a membrane driven by a piezoelectric actuator. A pressure ratio of about 1.11 was achieved with a filling pressure of 2.5MPa and compression volume of about 22.6mm3 when operating the actuator with a peak-to-peak sinusoidal voltage of 100V at a frequency of 1kHz. The electrical power input was 2.73W. The high pressure ratio and low electrical input power at high frequencies would herald development of microminiature cryocoolers.
Oscillating instanton solutions in curved space
Lee, Bum-Hoon; Lee, Chul H.; Lee, Wonwoo; Oh, Changheon
2012-01-01
We investigate oscillating instanton solutions of a self-gravitating scalar field between degenerate vacua. We show that there exist O(4)-symmetric oscillating solutions in a de Sitter background. The geometry of this solution is finite and preserves the Z2 symmetry. The nontrivial solution corresponding to tunneling is possible only if the effect of gravity is taken into account. We present numerical solutions of this instanton, including the phase diagram of solutions in terms of the parameters of the present work and the variation of energy densities. Our solutions can be interpreted as solutions describing an instanton-induced domain wall or braneworld-like object rather than a kink-induced domain wall or braneworld. The oscillating instanton solutions have a thick wall and the solutions can be interpreted as a mechanism providing nucleation of the thick wall for topological inflation. We remark that Z2 invariant solutions also exist in a flat and anti-de Sitter background, though the physical significance is not clear.
Synchronization of mobile chaotic oscillator networks
Energy Technology Data Exchange (ETDEWEB)
Fujiwara, Naoya, E-mail: fujiwara@csis.u-tokyo.ac.jp [Center for Spatial Information Science, The University of Tokyo, 277-8568 Chiba (Japan); Kurths, Jürgen [Potsdam Institute for Climate Impact Research (PIK), 14473 Potsdam, Germany and Institute for Complex Systems and Mathematical Biology, University of Aberdeen, Aberdeen (United Kingdom); Díaz-Guilera, Albert [Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain and Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, Barcelona (Spain)
2016-09-15
We study synchronization of systems in which agents holding chaotic oscillators move in a two-dimensional plane and interact with nearby ones forming a time dependent network. Due to the uncertainty in observing other agents' states, we assume that the interaction contains a certain amount of noise that turns out to be relevant for chaotic dynamics. We find that a synchronization transition takes place by changing a control parameter. But this transition depends on the relative dynamic scale of motion and interaction. When the topology change is slow, we observe an intermittent switching between laminar and burst states close to the transition due to small noise. This novel type of synchronization transition and intermittency can happen even when complete synchronization is linearly stable in the absence of noise. We show that the linear stability of the synchronized state is not a sufficient condition for its stability due to strong fluctuations of the transverse Lyapunov exponent associated with a slow network topology change. Since this effect can be observed within the linearized dynamics, we can expect such an effect in the temporal networks with noisy chaotic oscillators, irrespective of the details of the oscillator dynamics. When the topology change is fast, a linearized approximation describes well the dynamics towards synchrony. These results imply that the fluctuations of the finite-time transverse Lyapunov exponent should also be taken into account to estimate synchronization of the mobile contact networks.
The stability of large oscillating bubbles
Blake, John; Pearson, Antony
2002-11-01
In a most remarkable paper, in October 1942, Penney & Price developed a theory for the stability of large oscillating bubbles; in their case they were interested in underwater explosions. Much of our current understanding on the stability of oscillating bubbles can be traced to the theoretical and experimental insight shown in this paper. While interest in this particular area continues with regard ship survivability to underwater explosions, other newer areas include the oscillatory behaviour of of seismic airgun generated bubbles. Apart from large volume oscillations with a characteristic period, the other dominant parameter is associated with buoyancy. An appropriate parameter is chosen that provides a measure of the distance of migration of a bubble over one period. An analytical and computational analysis of this class of problem reveals that this pressure gradient driven instability, normally observed in the form of a high speed liquid jet threading the bubble, is the most dominant surface instability, a characteristic feature borne out in most experimental and practical applications due to the presence of an incipient pressure gradient associated with hydrostatics, dynamics or boundaries
Decadal Oscillation of Fall Temperature in Taiwan
Directory of Open Access Journals (Sweden)
Jau-Ming Chen
2008-01-01
Full Text Available This study verifies the existence of an evident decadal oscillation in fall (September - November temperature for Taiwan. It has an island-wide spatial pattern and a central frequency of 11 years. Acorresponding decadal-oscillation mode of tropical sea surface temperature (SST is found to be largely responsible for inducing the decadal temperature oscillation for Taiwan via the following regulating processes. On a decadal timescale, periods of decadal warming in Taiwan concur with major cold anomalies in tropical SST over the eastern Indian Ocean and the central Pacific. These cold SST anomalies modulate tropical Walker circulation so as to produce anomalous descending centers in their regions. Meanwhile, the complementary anomalous ascending motion and anomalous low-level convergence center occur near the Maritime continent. These anomalous ascending and descending centers act as tropical forcing sources to evoke a low-level Rossby-wave-like circulation anomaly in the Asian-Pacific regions. Taiwan is surrounded by a low-level anomalous high to its east and an anomalous low to its west. These circulations induce anomalous flows from the south to warm Taiwan via anomalous warm advection. The above regulating processes reverse in polarity during periods of decadal cooling in Taiwan.
Seasonal predictability of the North Atlantic Oscillation
Vellinga, Michael; Scaife, Adam
2015-04-01
Until recently, long-range forecast systems showed only modest levels of skill in predicting surface winter climate around the Atlantic Basin and associated fluctuations in the North Atlantic Oscillation at seasonal lead times. Here we use a new forecast system to assess seasonal predictability of winter North Atlantic climate. We demonstrate that key aspects of European and North American winter climate and the surface North Atlantic Oscillation are highly predictable months ahead. We demonstrate high levels of prediction skill in retrospective forecasts of the surface North Atlantic Oscillation, winter storminess, near-surface temperature, and wind speed, all of which have high value for planning and adaptation to extreme winter conditions. Analysis of forecast ensembles suggests that while useful levels of seasonal forecast skill have now been achieved, key sources of predictability are still only partially represented and there is further untapped predictability. This work is distributed under the Creative Commons Attribution 3.0 Unported License together with an author copyright. This license does not conflict with the regulations of the Crown Copyright.
Direct limits on the oscillation frequency.
Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Agelou, M; Agram, J-L; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Askew, A; Asman, B; Assis Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, P; Banerjee, S; Barberis, E; Bargassa, P; Baringer, P; Barnes, C; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Binder, M; Biscarat, C; Black, K M; Blackler, I; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Blumenschein, U; Boehnlein, A; Boeriu, O; Bolton, T A; Borcherding, F; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Burdin, S; Burke, S; Burnett, T H; Busato, E; Buszello, C P; Butler, J M; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Chapin, D; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Claes, D; Clément, B; Clément, C; Coadou, Y; Cooke, M; Cooper, W E; Coppage, D; Corcoran, M; Cousinou, M-C; Cox, B; Crépé-Renaudin, S; Cutts, D; Cwiok, M; da Motta, H; Das, A; Das, M; Davies, B; Davies, G; Davis, G A; De, K; de Jong, P; de Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Demine, P; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Doidge, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Edwards, T; Ellison, J; Elmsheuser, J; Elvira, V D; Eno, S; Ermolov, P; Estrada, J; Evans, H; 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Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rani, K J; Ranjan, K; Rapidis, P A; Ratoff, P N; Renkel, P; Reucroft, S; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Royon, C; Rubinov, P; Ruchti, R; Rud, V I; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schmitt, C; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sengupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shephard, W D; Shivpuri, R K; Shpakov, D; Siccardi, V; Sidwell, R A; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smith, R P; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Song, X; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stark, J; Steele, J; Stevenson, K; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strang, M A; Strauss, M; Ströhmer, R; Strom, D; Strovink, M; Stutte, L; Sumowidagdo, S; Sznajder, A; Talby, M; Tamburello, P; Taylor, W; Telford, P; Temple, J; Tiller, B; Titov, M; Tokmenin, V V; Tomoto, M; Toole, T; Torchiani, I; Towers, S; Trefzger, T; Trincaz-Duvoid, S; Tsybychev, D; Tuchming, B; Tully, C; Turcot, A S; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; van den Berg, P J; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vartapetian, A; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Seguier, F; Vint, P; Vlimant, J-R; Von Toerne, E; Voutilainen, M; Vreeswijk, M; Wahl, H D; Wang, L; Warchol, J; Watts, G; Wayne, M; Weber, M; Weerts, H; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Womersley, J; Wood, D R; Wyatt, T R; Xie, Y; Xuan, N; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, C; Yu, J; Yurkewicz, A; Zatserklyaniy, A; Zeitnitz, C; Zhang, D; Zhao, T; Zhao, Z; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zutshi, V; Zverev, E G
2006-07-14
We report results of a study of the B(s)(0) oscillation frequency using a large sample of B(s)(0) semileptonic decays corresponding to approximately 1 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2006. The amplitude method gives a lower limit on the B(s)(0) oscillation frequency at 14.8 ps(-1) at the 95% C.L. At delta m(s) = 19 ps(-1), the amplitude deviates from the hypothesis A= 0(1) by 2.5 (1.6) standard deviations, corresponding to a two-sided C.L. of 1% (10%). A likelihood scan over the oscillation frequency, delta m(s), gives a most probable value of 19 ps(-1) and a range of 17 < delta m(s) < 21 ps(-1)at the 90% C.L., assuming Gaussian uncertainties. This is the first direct two-sided bound measured by a single experiment. If delta m(s) lies above 22 ps(-1), then the probability that it would produce a likelihood minimum similar to the one observed in the interval 16-22 ps(-1) is (5.0 +/- 0.3)%.
Oscillation results for certain fractional difference equations
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Zhiyun WANG
2017-08-01
Full Text Available Fractional calculus is a theory that studies the properties and application of arbitrary order differentiation and integration. It can describe the physical properties of some systems more accurately, and better adapt to changes in the system, playing an important role in many fields. For example, it can describe the process of tumor growth (growth stimulation and growth inhibition in biomedical science. The oscillation of solutions of two kinds of fractional difference equations is studied, mainly using the proof by contradiction, that is, assuming the equation has a nonstationary solution. For the first kind of equation, the function symbol is firstly determined, and by constructing the Riccati function, the difference is calculated. Then the condition of the function is used to satisfy the contradiction, that is, the assumption is false, which verifies the oscillation of the solution. For the second kind of equation with initial condition, the equivalent fractional sum form of the fractional difference equation are firstly proved. With considering 0<α≤1 and α>1, respectively, by using the properties of Stirling formula and factorial function, the contradictory is got through enhanced processing, namely the assuming is not established, and the sufficient condition for the bounded solutions of the fractional difference equation is obtained. The above results will optimize the relevant conclusions and enrich the relevant results. The results are applied to the specific equations, and the oscillation of the solutions of equations is proved.
Skyrmion motion driven by oscillating magnetic field.
Moon, Kyoung-Woong; Kim, Duck-Ho; Je, Soong-Geun; Chun, Byong Sun; Kim, Wondong; Qiu, Z Q; Choe, Sug-Bong; Hwang, Chanyong
2016-02-05
The one-dimensional magnetic skyrmion motion induced by an electric current has attracted much interest because of its application potential in next-generation magnetic memory devices. Recently, the unidirectional motion of large (20 μm in diameter) magnetic bubbles with two-dimensional skyrmion topology, driven by an oscillating magnetic field, has also been demonstrated. For application in high-density memory devices, it is preferable to reduce the size of skyrmion. Here we show by numerical simulation that a skyrmion of a few tens of nanometres can also be driven by high-frequency field oscillations, but with a different direction of motion from the in-plane component of the tilted oscillating field. We found that a high-frequency field for small skyrmions can excite skyrmion resonant modes and that a combination of different modes results in a final skyrmion motion with a helical trajectory. Because this helical motion depends on the frequency of the field, we can control both the speed and the direction of the skyrmion motion, which is a distinguishable characteristic compared with other methods.
Thermal explosion in oscillating ambient conditions
Novozhilov, Vasily
2016-01-01
Thermal explosion problem for a medium with oscillating ambient temperature at its boundaries is considered. This is a new problem in thermal explosion theory, not previously considered in a distributed system formulation, but important for combustion and fire science. It describes autoignition of wide range of fires (such as but not limited to piles of biosolids and other organic matter; storages of munitions, explosives, propellants) subjected to temperature variations, such as seasonal or day/night variation. The problem is considered in formulation adopted in classical studies of thermal explosion. Critical conditions are determined by frequency and amplitude of ambient temperature oscillations, as well as by a number of other parameters. Effects of all the parameters on critical conditions are quantified. Results are presented for the case of planar symmetry. Development of thermal explosion in time is also considered, and a new type of unsteady thermal explosion development is discovered where thermal runaway occurs after several periods of temperature oscillations within the medium. PMID:27443235
Numerical Analysis of an Oscillating Micromixer
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B. Dennai
2009-12-01
Full Text Available Micromixing is particularly interesting for many microfluidic applications. In micrometric size devices, reaching an efficient mixing is often difficult, due to laminarization of the flow. Several solutions are proposed in the literature to overcome this issue. As an example, efficient mixing may be obtained using a secondary pulsed flow to destabilize the diffusion layer between the two fluids to mix. This layer is then stretched and folded, which leads to an improved chaotic mixing [Dodge et al., 2004]. However, this technique requires a specific actuation, which makes the microsystem more complex. In this paper, we study an autopulsating micromixer based on a microfluidic oscillator, the principle of which takes advantage of the Coanda effect. Oscillations of the flow are self generated, which widely simplifies the micromixer design. Different geometries are numerically investigated both for liquid and gaseous fluids using the CFD Code. The simulated frequency of oscillations is compared with analytical predictions and experimental data obtained in a millimetric sized mixer. Mixing efficiency is quantified and discussed in function of the flow structure, both for incompressible and compressible fluids, for millimetric and micrometric sizes
Electron beam modification of vanadium dioxide oscillators
Energy Technology Data Exchange (ETDEWEB)
Belyaev, Maksim; Velichko, Andrey; Putrolaynen, Vadim; Perminov, Valentin; Pergament, Alexander [Petrozavodsk State University, Petrozavodsk (Russian Federation)
2017-03-15
The paper presents the results of a study of electron-beam modification (EBM) of VO{sub 2}-switch I-V curve threshold parameters and the self-oscillation frequency of a circuit containing such a switching device. EBM in vacuum is reversible and the parameters are restored when exposed to air at pressure of 150 Pa. At EBM with a dose of 3 C cm{sup -2}, the voltages of switching-on (V{sub th}) and off (V{sub h}), as well as the OFF-state resistance R{sub off}, decrease down to 50% of the initial values, and the oscillation frequency increases by 30% at a dose of 0.7 C cm{sup -2}. Features of physics of EBM of an oscillator are outlined considering the contribution of the metal and semiconductor phases of the switching channel. Controlled modification allows EBM forming of switches with preset parameters. Also, it might be used in artificial oscillatory neural networks for pattern recognition based on frequency shift keying. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Oscillating side-branch enhancements of thermoacoustic heat exchangers
Swift, Gregory W.
2003-05-13
A regenerator-based engine or refrigerator has a regenerator with two ends at two different temperatures, through which a gas oscillates at a first oscillating volumetric flow rate in the direction between the two ends and in which the pressure of the gas oscillates, and first and second heat exchangers, each of which is at one of the two different temperatures. A dead-end side branch into which the gas oscillates has compliance and is connected adjacent to one of the ends of the regenerator to form a second oscillating gas flow rate additive with the first oscillating volumetric flow rate, the compliance having a volume effective to provide a selected total oscillating gas volumetric flow rate through the first heat exchanger. This configuration enables the first heat exchanger to be configured and located to better enhance the performance of the heat exchanger rather than being confined to the location and configuration of the regenerator.
Temporal structure of neuronal population oscillations with empirical model decomposition
Energy Technology Data Exchange (ETDEWEB)
Li Xiaoli [Institute of Electrical Engineering, Yanshan University, Qinhuangdao 066004 (China)]. E-mail: xiaoli.avh@gmail.com
2006-08-07
Frequency analysis of neuronal oscillation is very important for understanding the neural information processing and mechanism of disorder in the brain. This Letter addresses a new method to analyze the neuronal population oscillations with empirical mode decomposition (EMD). Following EMD of neuronal oscillation, a series of intrinsic mode functions (IMFs) are obtained, then Hilbert transform of IMFs can be used to extract the instantaneous time frequency structure of neuronal oscillation. The method is applied to analyze the neuronal oscillation in the hippocampus of epileptic rats in vivo, the results show the neuronal oscillations have different descriptions during the pre-ictal, seizure onset and ictal periods of the epileptic EEG at the different frequency band. This new method is very helpful to provide a view for the temporal structure of neural oscillation.
An analytical formulation for phase noise in MEMS oscillators.
Agrawal, Deepak; Seshia, Ashwin
2014-12-01
In recent years, there has been much interest in the design of low-noise MEMS oscillators. This paper presents a new analytical formulation for noise in a MEMS oscillator encompassing essential resonator and amplifier nonlinearities. The analytical expression for oscillator noise is derived by solving a second-order nonlinear stochastic differential equation. This approach is applied to noise modeling of an electrostatically addressed MEMS resonator-based square-wave oscillator in which the resonator and oscillator circuit nonlinearities are integrated into a single modeling framework. By considering the resulting amplitude and phase relations, we derive additional noise terms resulting from resonator nonlinearities. The phase diffusion of an oscillator is studied and the phase diffusion coefficient is proposed as a metric for noise optimization. The proposed nonlinear phase noise model provides analytical insight into the underlying physics and a pathway toward the design optimization for low-noise MEMS oscillators.
Typical patterns of oscillations in three-phase circuit
Hisakado, Takashi; Ukai, Shota
Symmetrical three-phase circuits are fundamental models of power systems. Although the circuits have structural symmetry, asymmetric patterns of oscillations have been observed in real power systems. This paper describes an approach to understanding typical patterns of oscillations in the three-phase circuits using symmetry. In order to figure out oscillation patterns, we introduce a three LC ladder circuit which has a higher symmetry than the three-phase circuit. Using only the symmetries of the three LC ladder circuit, we classify periodic oscillations and construct a lattice of those modes. Further, extending the method to almost periodic oscillations, we decompose and characterize typical almost periodic oscillations by their symmetry. Finally, by observing a global phase space in the three LC ladder circuit, we confirm typical oscillations in the three-phase circuit.
Classification of attractors for systems of identical coupled Kuramoto oscillators
Energy Technology Data Exchange (ETDEWEB)
Engelbrecht, Jan R. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Mirollo, Renato [Department of Mathematics, Boston College, Chestnut Hill, Massachusetts 02467 (United States)
2014-03-15
We present a complete classification of attractors for networks of coupled identical Kuramoto oscillators. In such networks, each oscillator is driven by the same first-order trigonometric function, with coefficients given by symmetric functions of the entire oscillator ensemble. For N≠3 oscillators, there are four possible types of attractors: completely synchronized fixed points or limit cycles, and fixed points or limit cycles where all but one of the oscillators are synchronized. The case N = 3 is exceptional; systems of three identical Kuramoto oscillators can also posses attracting fixed points or limit cycles with all three oscillators out of sync, as well as chaotic attractors. Our results rely heavily on the invariance of the flow for such systems under the action of the three-dimensional group of Möbius transformations, which preserve the unit disc, and the analysis of the possible limiting configurations for this group action.
Oscillations of the Outer Boundary of the Outer Radiation Belt During Sawtooth Oscillations
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Jae-Hun Kim
2006-09-01
Full Text Available We report three sawtooth oscillation events observed at geosynchronous orbit where we find quasi-periodic (every 2-3 hours sudden flux increases followed by slow flux decreases at the energy levels of ˜50-400 keV. For these three sawtooth events, we have examined variations of the outer boundary of the outer radiation belt. In order to determine L values of the outer boundary, we have used data of relativistic electron flux observed by the SAMPEX satellite. We find that the outer boundary of the outer radiation belt oscillates periodically being consistent with sawtooth oscillation phases. Specifically, the outer boundary of the outer radiation belt expands (namely, the boundary L value increases following the sawtooth particle flux enhancement of each tooth, and then contracts (namely, the boundary L value decreases while the sawtooth flux decreases gradually until the next flux enhancement. On the other hand, it is repeatedly seen that the asymmetry of the magnetic field intensity between dayside and nightside decreases (increases due to the dipolarization (the stretching on the nightside as the sawtooth flux increases (decreases. This implies that the periodic magnetic field variations during the sawtooth oscillations are likely responsible for the expansion-contraction oscillations of the outer boundary of the outer radiation belt.
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Sheng-Jun Wang
2011-06-01
Full Text Available Cerebral cortical brain networks possess a number of conspicuous features of structure and dynamics. First, these networks have an intricate, non-random organization. They are structured in a hierarchical modular fashion, from large-scale regions of the whole brain, via cortical areas and area subcompartments organized as structural and functional maps to cortical columns, and ﬁnally circuits made up of individual neurons. Second, the networks display self-organized sustained activity, which is persistent in the absence of external stimuli. At the systems level, such activity is characterized by complex rhythmical oscillations over a broadband background, while at the cellular level, neuronal discharges have been observed to display avalanches, indicating that cortical networks are at the state of self-organized criticality. We explored the relationship between hierarchical neural network organization and sustained dynamics using large-scale network modeling. It was shown that sparse random networks with balanced excitation and inhibition can sustain neural activity without external stimulation. We ﬁnd that a hierarchical modular architecture can generate sustained activity better than random networks. Moreover, the system can simultaneously support rhythmical oscillations and self-organized criticality, which are not present in the respective random networks. The underlying mechanism is that each dense module cannot sustain activity on its own, but displays self-organized criticality in the presence of weak perturbations. The hierarchical modular networks provide the coupling among subsystems with self-organized criticality. These results imply that the hierarchical modular architecture of cortical networks plays an important role in shaping the ongoing spontaneous activity of the brain, potentially allowing the system to take advantage of both the sensitivityof critical state and predictability and timing of oscillations for efficient
Energy Technology Data Exchange (ETDEWEB)
Dotsenko, Viktor S [Landau Institute for Theoretical Physics, Russian Academy of Sciences, Moscow (Russian Federation)
2011-03-31
In the last two decades, it has been established that a single universal probability distribution function, known as the Tracy-Widom (TW) distribution, in many cases provides a macroscopic-level description of the statistical properties of microscopically different systems, including both purely mathematical ones, such as increasing subsequences in random permutations, and quite physical ones, such as directed polymers in random media or polynuclear crystal growth. In the first part of this review, we use a number of models to examine this phenomenon at a simple qualitative level and then consider the exact solution for one-dimensional directed polymers in a random environment, showing that free energy fluctuations in such a system are described by the universal TW distribution. The second part provides detailed appendix material containing the necessary mathematical background for the first part. (reviews of topical problems)
MEMS-BASED OSCILLATORS: A REVIEW
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Jamilah Karim
2014-05-01
Full Text Available ABSTRACT: This paper presents an overview of microelectromechanical (MEMS based oscillators. The accuracy and stability of the reference frequency will normally limit the performance of most wireless communication systems. MEMS technology is the technology of choice due to its compatibility to silicon, leading to integration with circuits and lowering power consumption. MEMS based oscillators also provide the potential of a fully integrated transceiver. The most commonly used topology for MEMS based oscillators are pierce oscillator circuit topology and TIA circuit topology. Both topologies result in very competitive output in terms of phase noise and power consumption. They can be used for either higher or lower Rx. The major difference between both topologies is the number of transistors used. TIA circuit used more number of transistor compare to pierce circuit. Thus design complexity of the TIA is higher. Pierce circuit is simpler, provide straightforward biasing and easier to design. The highly integratable of MEMS-based oscillators have made them much needed in future multiband wireless system. So that future wireless systems are able to function globally without any problem. ABSTRAK: Kertas kerja ini membentangkan gambaran keseluruhan mikroelektromekanikal (MEMS berdasarkan pengayun. Ketepatan dan kestabilan frekuensi rujukan sering membataskan perlaksanaan kebanyakan sistem komunikasi tanpa wayar. Teknologi MEMS merupakan teknologi pilihan memandangkan ia serasi dengan silikon; membolehkan integrasi dengan litar dan penggunaan tenaga yang rendah. Pengayun berdasarkan MEMS juga berpotensi sebagai integrasi penuh penghantar-terima. Topologi yang sering digunakan untuk pengayun berdasarkan MEMS adalah topologi litar pengayun pencantas dan topologi litar TIA. Keputusan bagi kedua-dua topologi adalah amat kompetitif dari segi fasa bunyi dan penggunaan tenaga. Ia boleh digunakan untuk meninggikan atau merendahkan Rx. Perbezaan utama
Equatorial Oscillations in Jupiter's and Saturn's Atmospheres
Flasar, F. Michael; Guerlet, S.; Fouchet, T.; Schinder, P. J.
2011-01-01
Equatorial oscillations in the zonal-mean temperatures and zonal winds have been well documented in Earth's middle atmosphere. A growing body of evidence from ground-based and Cassini spacecraft observations indicates that such phenomena also occur in the stratospheres of Jupiter and Saturn. Earth-based midinfrared measurements spanning several decades have established that the equatorial stratospheric temperatures on Jupiter vary with a cycle of 4-5 years and on Saturn with a cycle of approximately 15 years. Spectra obtained by the Composite Infrared Spectrometer (CIRS) during the Cassini swingby at the end of 2000, with much better vertical resolution than the ground-based data, indicated a series of vertically stacked warm and cold anomalics at Jupiter's equator; a similar structurc was seen at Saturn's equator in CIRS limb measurements made in 2005, in the early phase of Cassini's orbital tour. The thermal wind equation implied similar patterns of mean zonal winds increasing and decreasing with altitude. On Saturn the peak-to-pcak amplitude of this variation was nearly 200 meters per second. The alternating vertical pattern of wanner and colder cquatorial tcmperatures and easterly and westerly tendencies of the zonal winds is seen in Earth's equatorial oscillations, where the pattern descends with time, The Cassini Jupiter and early Saturn observations were snapshots within a limited time interval, and they did not show the temporal evolution of the spatial patterns. However, more recent Saturn observations by CIRS (2010) and Cassini radio-occultation soundings (2009-2010) have provided an opportunity to follow the change of the temperature-zonal wind pattern, and they suggest there is descent, at a rate of roughly one scale height over four years. On Earth, the observed descent in the zonal-mean structure is associated with the absorption of a combination of vertically propagating waves with easlerly and westerly phase velocities. The peak-to-peak zonal wind
Measuring Antineutrino Oscillations with the MINOS Experiment
Energy Technology Data Exchange (ETDEWEB)
Evans, Justin John [Univ. of Oxford (United Kingdom)
2008-09-01
MINOS is a long baseline neutrino oscillation experiment. A manmade beam of predominantly muon neutrinos is detected both 1 km and 735 km from the production point by two functionally identical detectors. A comparison of the energy spectra measured by the two detectors shows the energy-dependent disappearance of muon neutrinos characteristic of oscillations and allows a measurement of the parameters governing the oscillations. This thesis presents work leading to measurements of disappearance in the 6% $\\bar{v}$_{μ} background in that beam. A calibration is developed to correct for time-dependent changes in the responses of both detectors, reducing the corresponding uncertainty on hadronic energy measurements from 1.8% to 0.4% in the near detector and from 0.8% to 0.4% in the far detector. A method of selecting charged current $\\bar{v}$_{μ} events is developed, with purities (efficiencies) of 96.5% (74.4%) at the near detector, and 98.8% (70.9%) at the far detector in the region below 10 GeV reconstructed antineutrino energy. A method of using the measured near detector neutrino energy spectrum to predict that expected at the far detector is discussed, and developed for use in the $\\bar{v}$_{μ} analysis. Sources of systematic uncertainty contributing to the oscillation measurements are discussed. In the far detector, 32 charged current $\\bar{v}$_{μ} events are observed below a reconstructed energy of 30 GeV, compared to an expectation of 47.8 for Δ$\\bar{m}$_{atm}^{2} = Δ$\\bar{m}$_{atm}^{2}, sin^{2}(2$\\bar{θ}$_{23}) = sin^{2}(2θ_{23}). This deficit, in such a low-statistics sample, makes the result difficult to interpret in the context of an oscillation parameter measurement. Possible sources for the discrepancy are discussed, concluding that considerably more data are required for a definitive solution. Running MINOS with a dedicated $\\bar
Emergence and coherence of oscillations in star networks of stochastic excitable elements
Kromer, Justus A.; Schimansky-Geier, Lutz; Neiman, Alexander B.
2016-04-01
We study the emergence and coherence of stochastic oscillations in star networks of excitable elements in which peripheral nodes receive independent random inputs. A biophysical model of a distal branch of sensory neuron in which peripheral nodes of Ranvier are coupled to a central node by myelinated cable segments is used along with a generic model of networked stochastic active rotators. We show that coherent oscillations can emerge due to stochastic synchronization of peripheral nodes and that the degree of coherence can be maximized by tuning the coupling strength and the size of the network. Analytical results are obtained for the strong-coupling regime of the active rotator network. In particular, we show that in the strong-coupling regime, the network dynamics can be described by an effective single active rotator with rescaled parameters and noise.
Emergence and coherence of oscillations in star networks of stochastic excitable elements
Kromer, Justus A; Neiman, Alexander B
2015-01-01
We study the emergence and coherence of stochastic oscillations in star networks of excitable elements in which peripheral nodes receive independent random inputs. A biophysical model of a distal branch of sensory neuron in which peripheral nodes of Ranvier are coupled to a central node by myelinated cable segments is used along with a generic model of networked stochastic active rotators. We show that coherent oscillations can emerge due to stochastic synchronization of peripheral nodes and that the degree of coherence can be maximized by tuning the coupling strength and the size of the network. Analytical results are obtained for the strong coupling regime of the active rotator network. In particular, we show that in the strong coupling regime the network dynamics can be described by an effective single active rotator with rescaled parameters and noise.
Matula, Dominik
2013-01-01
The author summarizes some previous results concerning random triangles. He describes the Gaussian triangle and random triangles whose vertices lie in a unit n-dimensional ball, in a rectangle or in a general bounded convex set. In the second part, the author deals with an inscribed triangle in a triangle - let ABC be an equilateral triangle and let M, N, O be three points, each laying on one side of the ABC. We call MNO inscribed triangle (in an equi- laterral triangle). The median triangle ...
Mehta, Madan Lal
1990-01-01
Since the publication of Random Matrices (Academic Press, 1967) so many new results have emerged both in theory and in applications, that this edition is almost completely revised to reflect the developments. For example, the theory of matrices with quaternion elements was developed to compute certain multiple integrals, and the inverse scattering theory was used to derive asymptotic results. The discovery of Selberg's 1944 paper on a multiple integral also gave rise to hundreds of recent publications. This book presents a coherent and detailed analytical treatment of random matrices, leading
Witt, Annette; Palmigiano, Agostina; Neef, Andreas; El Hady, Ahmed; Wolf, Fred; Battaglia, Demian
2013-01-01
Dynamic oscillatory coherence is believed to play a central role in flexible communication between brain circuits. To test this communication-through-coherence hypothesis, experimental protocols that allow a reliable control of phase-relations between neuronal populations are needed. In this modeling study, we explore the potential of closed-loop optogenetic stimulation for the control of functional interactions mediated by oscillatory coherence. The theory of non-linear oscillators predicts that the efficacy of local stimulation will depend not only on the stimulation intensity but also on its timing relative to the ongoing oscillation in the target area. Induced phase-shifts are expected to be stronger when the stimulation is applied within specific narrow phase intervals. Conversely, stimulations with the same or even stronger intensity are less effective when timed randomly. Stimulation should thus be properly phased with respect to ongoing oscillations (in order to optimally perturb them) and the timing of the stimulation onset must be determined by a real-time phase analysis of simultaneously recorded local field potentials (LFPs). Here, we introduce an electrophysiologically calibrated model of Channelrhodopsin 2 (ChR2)-induced photocurrents, based on fits holding over two decades of light intensity. Through simulations of a neural population which undergoes coherent gamma oscillations—either spontaneously or as an effect of continuous optogenetic driving—we show that precisely-timed photostimulation pulses can be used to shift the phase of oscillation, even at transduction rates smaller than 25%. We consider then a canonic circuit with two inter-connected neural populations oscillating with gamma frequency in a phase-locked manner. We demonstrate that photostimulation pulses applied locally to a single population can induce, if precisely phased, a lasting reorganization of the phase-locking pattern and hence modify functional interactions between the
Directory of Open Access Journals (Sweden)
Annette eWitt
2013-04-01
Full Text Available Dynamic oscillatory coherence is believed to play a central role in flexible communication between brain circuits. To test this communication-through-coherence hypothesis, experimental protocols that allow a reliable control of phase-relations between neuronal populations are needed. In this modeling study, we explore the potential of closed-loop optogenetic stimulation for the control of functional interactions mediated by oscillatory coherence. The theory of nonlinear oscillators predicts that the efficacy of local stimulation will depend not only on the stimulation intensity but also on its timing relative to the ongoing oscillation in the target area. Induced phase-shifts are expected to be stronger when the stimulation is applied within specific narrow phase intervals. Conversely, stimulations with the same or even stronger intensity are less effective when timed randomly. Stimulation should thus be properly phased with respect to ongoing oscillations (in order to optimally perturb them and the timing of the stimulation onset must be determined by a real-time phase analysis of simultaneously recorded local field potentials (LFPs.Here, we introduce an electrophysiologically calibrated model of Channelrhodopsin 2 (ChR2-induced photocurrents, based on fits holding over two decades of light intensity. Through simulations of a neural population which undergoes coherent gamma oscillations —either spontaneously or as an effect of continuous optogenetic driving—, we show that precisely-timed photostimulation pulses can be used to shift phase, even at transduction rates smaller than 25%. We consider then a canonic circuit with two inter-connected neural populations oscillating with gamma frequency in a phase-locked manner. We demonstrate that photostimulation pulses applied locally to a single population can induce, if precisely phased, a lasting reorganization of the phase-locking pattern and hence modify functional interactions between the two
Papadopoulos, Lia; Kim, Jason Z.; Kurths, Jürgen; Bassett, Danielle S.
2017-07-01
Synchronization of non-identical oscillators coupled through complex networks is an important example of collective behavior, and it is interesting to ask how the structural organization of network interactions influences this process. Several studies have explored and uncovered optimal topologies for synchronization by making purposeful alterations to a network. On the other hand, the connectivity patterns of many natural systems are often not static, but are rather modulated over time according to their dynamics. However, this co-evolution and the extent to which the dynamics of the individual units can shape the organization of the network itself are less well understood. Here, we study initially randomly connected but locally adaptive networks of Kuramoto oscillators. In particular, the system employs a co-evolutionary rewiring strategy that depends only on the instantaneous, pairwise phase differences of neighboring oscillators, and that conserves the total number of edges, allowing the effects of local reorganization to be isolated. We find that a simple rule—which preserves connections between more out-of-phase oscillators while rewiring connections between more in-phase oscillators—can cause initially disordered networks to organize into more structured topologies that support enhanced synchronization dynamics. We examine how this process unfolds over time, finding a dependence on the intrinsic frequencies of the oscillators, the global coupling, and the network density, in terms of how the adaptive mechanism reorganizes the network and influences the dynamics. Importantly, for large enough coupling and after sufficient adaptation, the resulting networks exhibit interesting characteristics, including degree-frequency and frequency-neighbor frequency correlations. These properties have previously been associated with optimal synchronization or explosive transitions in which the networks were constructed using global information. On the contrary, by
Everard, Jeremy; Xu, Min; Bale, Simon
2012-03-01
This paper describes a greatly simplified model for the prediction of phase noise in oscillators which use a negative resistance as the active element. It is based on a simple circuit consisting of the parallel addition of a noise current, a negative admittance/resistance, and a parallel (Qlimited) resonant circuit. The transfer function is calculated as a forward trans-resistance (VOUT/IIN) and then converted to power. The effect of limiting is incorporated by assuming that the phase noise element of the noise floor is kT/2, i.e., -177 dBm/Hz at room temperature. The result is the same as more complex analyses, but enables a simple, clear insight into the operation of oscillators. The phase noise for a given power in the resonator appears to be lower than in feedback oscillators. The reasons for this are explained. Simulation and experimental results are included.
Asada, Masahiro; Suzuki, Safumi
2015-07-01
The resonant tunneling diode (RTD) is a candidate for a compact and coherent source in the terahertz frequency range. We show theoretically that the oscillation characteristics of RTDs are strongly affected by the external feedback of partially reflected output power. The oscillation frequency and output power largely change with a small amount of the reflected output power as a periodic function of the position of the reflection object. A change in the current-voltage curve, which can be used for the detection of the external feedback, also occurs.
Energy Technology Data Exchange (ETDEWEB)
Taniguchi, Tomohiro, E-mail: tomohiro-taniguchi@aist.go.jp; Kubota, Hitoshi; Imamura, Hiroshi [National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba 305-8568 (Japan); Tsunegi, Sumito [Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Ave. A. Fresnel, Palaiseau (France)
2015-05-07
Oscillation frequency of spin torque oscillator with a perpendicularly magnetized free layer and an in-plane magnetized pinned layer is theoretically investigated by taking into account the field-like torque. It is shown that the field-like torque plays an important role in finding the balance between the energy supplied by the spin torque and the dissipation due to the damping, which results in a steady precession. The validity of the developed theory is confirmed by performing numerical simulations based on the Landau-Lifshitz-Gilbert equation.
Mutual phase-locking of planar nano-oscillators
Directory of Open Access Journals (Sweden)
K. Y. Xu
2014-06-01
Full Text Available Characteristics of phase-locking between Gunn effect-based planar nano-oscillators are studied using an ensemble Monte Carlo (EMC method. Directly connecting two oscillators in close proximity, e.g. with a channel distance of 200 nm, only results in incoherent oscillations. In order to achieve in-phase oscillations, additional considerations must be taken into account. Two coupling paths are shown to exist between oscillators. One coupling path results in synchronization and the other results in anti-phase locking. The coupling strength through these two paths can be adjusted by changing the connections between oscillators. When two identical oscillators are in the anti-phase locking regime, fundamental components of oscillations are cancelled. The resulting output consists of purely second harmonic oscillations with a frequency of about 0.66 THz. This type of second harmonic generation is desired for higher frequency applications since no additional filter system is required. This transient phase-locking process is further analyzed using Adler's theory. The locking range is extracted, and a criterion for the channel length difference required for realizing phased arrays is obtained. This work should aid in designing nano-oscillator arrays for high power applications and developing directional transmitters for wireless communications.
Combustion-Driven Oscillation in Process Heaters
Energy Technology Data Exchange (ETDEWEB)
Seebold, J.G. [Chevron Corporation (Retired), 198 James Avenue, Atherton, CA 94027 (United States)
2005-10-15
At this moment in thousands of process heaters all over the world there are, to borrow a phrase from the late Carl Sagan, 'billions and billions' of Btu/hr beneficially being released entirely free of pulsation. On those few occasions, perhaps a dozen and a half in my career, when I would get the inevitable 'Why me?' call, I have generally responsed with something like, 'Consider yourself lucky, you have a rare scientific curiosity on your hands'. Reflecting on the solutions ultimately found, I'm reminded that many years ago my friend Abbott Putnam shared with me an early AGA (American Gas Association) field-service bulletin that included a prescription for eliminating combustion-driven oscillations in home heating units; viz., 'Drill a hole; if that doesn't work, drill another hole' or words to that effect. Many times have I wished that I still had a copy of that bulletin and in this paper we will have occasion, once again, to reflect upon the value of that advice. In this paper we will discuss an instance that arose in a pioneering installation of a breakthrough development of 'extremely', to distinguish it from 'ultra', low-NOx lean premix burner technology. We will illustrate how, when and under what circumstances combustion-driven oscillation can arise; we will touch on the many alternatives for its elimination that were considered and investigated; and we will discuss three practical alternatives for eliminating combustion-driven oscillations.
Thermal decay of Coulomb blockade oscillations
Idrisov, Edvin G.; Levkivskyi, Ivan P.; Sukhorukov, Eugene V.
2017-10-01
We study transport properties and the charge quantization phenomenon in a small metallic island connected to the leads through two quantum point contacts (QPCs). The linear conductance is calculated perturbatively with respect to weak tunneling and weak backscattering at QPCs as a function of the temperature T and gate voltage. The conductance shows Coulomb blockade (CB) oscillations as a function of the gate voltage that decay with the temperature as a result of thermally activated fluctuations of the charge in the island. The regimes of quantum T ≪EC and thermal T ≫EC fluctuations are considered, where EC is the charging energy of an isolated island. Our predictions for CB oscillations in the quantum regime coincide with previous findings by Furusaki and Matveev [Phys. Rev. B 52, 16676 (1995), 10.1103/PhysRevB.52.16676]. In the thermal regime the visibility of Coulomb blockade oscillations decays with the temperature as √{T /EC }exp(-π2T /EC) , where the exponential dependence originates from the thermal averaging over the instant charge fluctuations, while the prefactor has a quantum origin. This dependence does not depend on the strength of couplings to the leads. The differential capacitance, calculated in the case of a single tunnel junction, shows the same exponential decay, however the prefactor is linear in the temperature. This difference can be attributed to the nonlocality of the quantum effects. Our results agree with the recent experiment [Nature (London) 536, 58 (2016), 10.1038/nature19072] in the whole range of the parameter T /EC .
Reversing cells and oscillating motility proteins.
Leonardy, Simone; Bulyha, Iryna; Søgaard-Andersen, Lotte
2008-10-01
Cells of the bacterium Myxococcus xanthus organize into two types of patterns depending on their nutritional status, i.e. in the presence of nutrients cells form spreading colonies and in the absence of nutrients cells form fruiting bodies. Formation of both patterns depends on directed cell movements, which, in turn, depend on regulation of motility. M. xanthus cells harbor two motility machines, type IV pili and the A-engine, which act synergistically to generate motive force in the same direction. Periodically, the individual cells reverse their direction of movement. During a reversal the two motility machines switch polarity to generate force in the opposite direction. Recent evidence shows that at the molecular level, reversals involve pole-to-pole oscillations of motility proteins. Between reversals, these proteins localize to the cell poles to stimulate motility and in parallel with a reversal they relocalize between the poles. For two proteins, FrzS and RomR, which are part of the type IV pili and A-engine, respectively, it was directly demonstrated that they oscillate independently of each other but in synchrony, thus, providing evidence that the two motility machines switch polarity independently but synchronously. Protein oscillations are regulated and synchronized by the Frz chemosensory signal transduction system. The correct polarity of the motility systems is likely established by the MglA protein, which is a member of the Ras/Rac/Rho superfamily of small GTPases. In this scenario, MglA establishes the correct polarity of the two motility machines and the Frz-induced synchronized polarity switching maintains the correct polarity of the two motility machines.
Surface magnetostatic oscillations in elliptical bubble domains
Popov, M. A.; Zavislyak, I. V.
2009-01-01
A theory of surface magnetostatic oscillations in magnetic bubble domains with an elliptical cross section is presented. The dependences of the eigenfrequencies of resonant modes on the applied magnetic field are analyzed for a barium hexaferrite sample with allowance made for the change in the domain size due to a variation in the bias magnetic field. The range of frequency tuning in response to a magnetic field ranging from the elliptical instability field to the collapse field is estimated. It is demonstrated that elliptical bubble domains can be used as microminiature resonators operating in the millimeter range.
Relaxing Oscillation of the Machine-Unit
Directory of Open Access Journals (Sweden)
Bohumil Skala
2008-01-01
Full Text Available To understand the behavior of the Earth´s geomagnetic field, many theories have been created. One of the possible approaches is the Rikitake dynamo and chaotic theory. This paper describes the first step, i.e. how to verify the chaotic theory simulated result by a practical test. This first step is the oscillating machine unit. The asynchronous motor working point is moving from the stable part of its torque characteristic to the labile part due to the enormous loading. In the labile part the speed slows down and loading has to be decreased. Then the motor moves back to the stable part of characteristic.
Neutrino Oscillations and Non-standard Interactions
Directory of Open Access Journals (Sweden)
Yasaman Farzan
2018-02-01
Full Text Available Current neutrino experiments are measuring the neutrino mixing parameters with an unprecedented accuracy. The upcoming generation of neutrino experiments will be sensitive to subdominant neutrino oscillation effects that can in principle give information on the yet-unknown neutrino parameters: the Dirac CP-violating phase in the PMNS mixing matrix, the neutrino mass ordering and the octant of θ23. Determining the exact values of neutrino mass and mixing parameters is crucial to test various neutrino models and flavor symmetries that are designed to predict these neutrino parameters. In the first part of this review, we summarize the current status of the neutrino oscillation parameter determination. We consider the most recent data from all solar neutrino experiments and the atmospheric neutrino data from Super-Kamiokande, IceCube, and ANTARES. We also implement the data from the reactor neutrino experiments KamLAND, Daya Bay, RENO, and Double Chooz as well as the long baseline neutrino data from MINOS, T2K, and NOνA. If in addition to the standard interactions, neutrinos have subdominant yet-unknown Non-Standard Interactions (NSI with matter fields, extracting the values of these parameters will suffer from new degeneracies and ambiguities. We review such effects and formulate the conditions on the NSI parameters under which the precision measurement of neutrino oscillation parameters can be distorted. Like standard weak interactions, the non-standard interaction can be categorized into two groups: Charged Current (CC NSI and Neutral Current (NC NSI. Our focus will be mainly on neutral current NSI because it is possible to build a class of models that give rise to sizeable NC NSI with discernible effects on neutrino oscillation. These models are based on new U(1 gauge symmetry with a gauge boson of mass ≲ 10 MeV. The UV complete model should be of course electroweak invariant which in general implies that along with neutrinos, charged
Bistability in Coupled Oscillators Exhibiting Synchronized Dynamics
Olusola, O. I.; Vincent, U. E.; Njah, A. N.; Olowofela, J. A.
2010-05-01
We report some new results associated with the synchronization behavior of two coupled double-well Duffing oscillators (DDOs). Some sufficient algebraic criteria for global chaos synchronization of the drive and response DDOs via linear state error feedback control are obtained by means of Lyapunov stability theory. The synchronization is achieved through a bistable state in which a periodic attractor co-exists with a chaotic attractor. Using the linear perturbation analysis, the prevalence of attractors in parameter space and the associated bifurcations are examined. Subcritical and supercritical Hopf bifurcations and abundance of Arnold tongues — a signature of mode locking phenomenon are found.
Oscillations in a half-empty bottle
Bourges, Andréane; Chardac, Amélie; Caussarieu, Aude; Plihon, Nicolas; Taberlet, Nicolas
2018-02-01
When a half-empty bottle of water is pushed to roll on a flat surface, the oscillations of the fluid inside the bottle induce an overall jerky motion. These velocity fluctuations of the bottle are studied through simple laboratory experiments accessible to undergraduate students and can help them to grasp fundamental concepts in mechanics and hydrodynamics. We first demonstrate through an astute experiment that the rotation of the fluid and the bottle is decoupled. The equations of motion are then derived using a mechanical approach, while the hydrodynamics of the fluid motion is explained. Finally, the theory is tested against two benchmark experiments.
Classical Trajectories from Coherent Quantum Oscillations
Kadin, Alan
2013-03-01
In the conventional Copenhagen interpretation of quantum mechanics, classical behavior arises from microscopic coherent quantum systems only in the presence of decoherence on the macroscopic scale. On the contrary, we derive classical Hamiltonian trajectories for a confined quantum wave directly from coherent phase evolution on the microscopic scale, without decoherence or wavefunction collapse (see also). This suggests that the basis for classical macroscopic physics, including relativity, lies in the microscopic behavior of coherently oscillating quantum fields. An outline of such a theory will be presented, which resolves longstanding paradoxes involving wave-particle duality, quantum entanglement, and the quantum-to-classical transition.
LHC MD 2042: Persistent Injection Oscillations
Karpov, Ivan; Argyropoulos, Theodoros; Baudrenghien, Philippe; Chapochnikova, Elena; Timko, Helga; CERN. Geneva. ATS Department
2018-01-01
This MD note summarizes the measurements performed to study persistent longitudinal oscillations after injection into the LHC. It was found that they build up due to mismatch, and can lead to particle losses and uncontrolled bunch lengthening. For the ﬁrst time, proﬁle measurements and ObsBox data acquisitions were triggered at injection to obtain ﬁrst-turn data. The measurements took place on 16th September 2017 between 14:30 and 19:30, and between 27th November 2017 20:00 and 28th November 2017 04:00.
Radiation linewidth of flux-flow oscillators
DEFF Research Database (Denmark)
Koshelets, V.P.; Dmitriev, P.N.; Ermakov, A.B.
2001-01-01
The results of linewidth measurements on flux-flow oscillators (FFOs) of a new design with improved parameters are presented. Extensive measurements of the dependence of the free-running FFO linewidth on the differential resistances associated both with the bias current and the control-line current....... A phenomenological model of the FFO linewidth taking into account all known noise sources (both internal and external) is used to explain the FFO linewidth dependence on the experimental parameters. Finally, we discuss the feasibility of using an electronic phase-locking loop (PLL) over the entire FFO operational...
Hydrogen in an oscillating porous vycor glass
Energy Technology Data Exchange (ETDEWEB)
Kondo, Y.; Schindler, M.; Pobell, F. [Universitaet Bayreuth (Germany)
1995-10-01
The authors investigate hydrogen in porous Vycor glass with a torsional oscillator technique. Although our primary purpose is searching for a superfluid transition of hydrogen supercooled in Vycor, we find that hydrogen molecules which are adsorbed and liquefied in Vycor at T > T{sub 3} (triple point of bulk H{sub 2}) leave the Vycor when decreasing the temperature to below a characteristic value T{sub c} < T{sub 3}. We discuss this phenomenon in terms of a free enregy balance between solid/liquid hydrogen inside and outside the Vycor.
Analysis of Bs flavor oscillations at CDF
Energy Technology Data Exchange (ETDEWEB)
Guerreiro Leonardo, Nuno Teotonio Viegas [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2006-09-01
The search for and study of flavor oscillations in the neutral B_{s}B_{s} meson system is an experimentally challenging task. It constitutes a flagship analysis of the Tevatron physics program. In this dissertation, they develop an analysis of the time-dependent B_{s} flavor oscillations using data collected with the CDF detector. The data samples are formed of both fully and partially reconstructed B meson decays: B_{s} → D_{s}π(ππ) and B_{s} → D_{s}lv. A likelihood fitting framework is implemented and appropriate models and techniques developed for describing the mass, proper decay time, and flavor tagging characteristics of the data samples. The analysis is extended to samples of B^{+} and B^{0} mesons, which are further used for algorithm calibration and method validation. The B mesons lifetimes are extracted. The measurement of the B^{0} oscillation frequency yields Δm_{d} = 0.522 ± 0.017 ps^{-1}. The search for B_{s} oscillations is performed using an amplitude method based on a frequency scanning procedure. Applying a combination of lepton and jet charge flavor tagging algorithms, with a total tagging power ϵ'D^{2} of 1.6%, to a data sample of 355 pb^{-1}, a sensitivity of 13.0 ps^{-1} is achieved. They develop a preliminary same side kaon tagging algorithm, which is found to provide a superior tagging power of about 4.0% for the B_{s} meson species. A study of the dilution systematic uncertainties is not reported. From its application as is to the B_{s} samples the sensitivity is significantly increased to about 18 ps^{-1} and a hint of a signal is seen at about 175. ps^{-1}. They demonstrate that the extension of the analysis to the increasing data samples with the inclusion of the same side tagging algorithm is capable of providing an observation of B_{s} mixing beyond the
A global analysis of neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Fogli, G.L. [Dipartimento Interateneo di Fisica “Michelangelo Merlin”, Via Amendola 173, 70126 Bari (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Lisi, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Marrone, A. [Dipartimento Interateneo di Fisica “Michelangelo Merlin”, Via Amendola 173, 70126 Bari (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy); Montanino, D. [Dipartimento di Matematica e Fisica “Ennio De Giorgi”, Via Arnesano, 73100 Lecce (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Lecce, Via Arnesano, 73100 Lecce (Italy); Palazzo, A. [Cluster of Excellence, Origin and Structure of the Universe, Technische Universität München, Boltzmannstraße 2, D-85748 Garching (Germany); Rotunno, A.M. [Dipartimento Interateneo di Fisica “Michelangelo Merlin”, Via Amendola 173, 70126 Bari (Italy)
2013-02-15
We present a global analysis of neutrino oscillation data, including high-precision measurements of the neutrino mixing angle θ{sub 13} at reactor experiments, which have confirmed previous indications in favor of θ{sub 13}>0. Recent data presented at this Conference are also included. We focus on the correlations between θ{sub 13} and the mixing angle θ{sub 23}, as well as between θ{sub 13} and the neutrino CP-violation phase δ. We find interesting indications for θ{sub 23}<π/4 and possible hints for δ∼π, with no significant difference between normal and inverted mass hierarchy.
Chimera states in mechanical oscillator networks
DEFF Research Database (Denmark)
Martens, Erik Andreas; Thutupalli, Shashi; Fourrière, Antoine
2013-01-01
of whether chimeras are indeed characteristic of natural systems. This calls for a palpable realization of chimera states without any fine-tuning, from which physical mechanisms underlying their emergence can be uncovered. Here, we devise a simple experiment with mechanical oscillators coupled...... in our experiments is controlled by elementary dynamical equations from mechanics that are ubiquitous in many natural and technological systems. The symmetry-breaking mechanism revealed by our experiments may thus be prevalent in systems exhibiting collective behavior, such as power grids, optomechanical...
Supersymmetry, quark confinement and the harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Bruce, S A; Minning, P C [Department of Physics, University of Concepcion, PO Box 160C, Concepcion (Chile)
2007-12-07
We study some quantum systems described by noncanonical commutation relations formally expressed as [q-hat,p-hat] = i h-bar(I-hat+{chi}-hatH-hat{sub HO}), where H-hat{sub HO} is the associated (harmonic-oscillator-like) Hamiltonian of the system and {chi}-hat is a Hermitian (constant) operator, i.e. [H-hat{sub HO},{chi}-hat]=O-hat. In passing, we also consider a simple ({chi}-hat=O-hat canonical) model, in the framework of a relativistic Klein-Gordon-like wave equation.
A Thermal Oscillating Two-Stream Instability
DEFF Research Database (Denmark)
Dysthe, K. B.; Mjølhus, E.; Pécseli, H. L.
1983-01-01
A theory for the oscillating two‐stream instability, in which the Ohmic heating of the electrons constitutes the nonlinearity, is developed for an inhomogeneous and magnetized plasma. Its possible role in explaining short‐scale, field‐aligned irregularities observed in ionospheric heating...... experiments is emphasized. The theory predicts that the initial growth of such irregularities is centered around the level of upper hybrid resonance. Furthermore, plane disturbances nearly parallel to the magnetic meridian plane have the largest growth rates. Expressions for threshold, growth rate...
Burst Oscillations: Watching Neutron Stars Spin
Strohmayer, Tod
2010-01-01
It is now almost 15 years since the first detection of rotationally modulated emission from X-ray bursting neutron stars, "burst oscillations," This phenomenon enables us to see neutron stars spin, as the X-ray burst flux asymmetrically lights up the surface. It has enabled a new way to probe the neutron star spin frequency distribution, as well as to elucidate the multidimensional nature of nuclear burning on neutron stars. I will review our current observational understanding of the phenomenon, with an eye toward highlighting some of the interesting remaining puzzles, of which there is no shortage.
Coherent Population Oscillation-Based Light Storage
Neveu, P.; Maynard, M.-A.; Bouchez, R.; Lugani, J.; Ghosh, R.; Bretenaker, F.; Goldfarb, F.; Brion, E.
2017-02-01
We theoretically study the propagation and storage of a classical field in a Λ -type atomic medium using coherent population oscillations (CPOs). We show that the propagation eigenmodes strongly relate to the different CPO modes of the system. Light storage in such modes is discussed by introducing a "populariton" quantity, a mixture of populations and field, by analogy to the dark state polariton used in the context of electromagnetically induced transparency light storage protocol. As experimentally shown, this memory relies on populations and is then—by contrast with usual Raman coherence optical storage protocols—robust to dephasing effects.
Seismic metamaterials based on isochronous mechanical oscillators
Energy Technology Data Exchange (ETDEWEB)
Finocchio, G., E-mail: gfinocchio@unime.it; Garescì, F.; Azzerboni, B. [Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, C.da di Dio, I-98166 Messina (Italy); Casablanca, O.; Chiappini, M. [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via Vigna Murata 605, 00143 Roma (Italy); Ricciardi, G. [Department of Civil, Informatic, Architectural, and Environmental Engineering and Applied Mathematics, C.da di Dio, I-98166 Messina (Italy); Alibrandi, U. [Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576 (Singapore)
2014-05-12
This Letter introduces a seismic metamaterial (SM) composed by a chain of mass-in-mass system able to filter the S-waves of an earthquake. We included the effect of the SM into the mono dimensional model for the soil response analysis. The SM modifies the soil behavior and in presence of an internal damping the amplitude of the soil amplification function is reduced also in a region near the resonance frequency. This SM can be realized by a continuous structure with inside a 3d-matrix of isochronous oscillators based on a sphere rolling over a cycloidal trajectory.
A Design Principle for a Posttranslational Biochemical Oscillator
Directory of Open Access Journals (Sweden)
Craig C. Jolley
2012-10-01
Full Text Available Multisite phosphorylation plays an important role in biological oscillators such as the circadian clock. Its general role, however, has been elusive. In this theoretical study, we show that a simple substrate with two modification sites acted upon by two opposing enzymes (e.g., a kinase and a phosphatase can show oscillations in its modification state. An unbiased computational analysis of this oscillator reveals two common characteristics: a unidirectional modification cycle and sequestering of an enzyme by a specific modification state. These two motifs cause a substrate to act as a coupled system in which a unidirectional cycle generates single-molecule oscillators, whereas sequestration synchronizes the population by limiting the available enzyme under conditions in which substrate is in excess. We also demonstrate the conditions under which the oscillation period is temperature compensated, an important feature of the circadian clock. This theoretical model will provide a framework for analyzing and synthesizing posttranslational oscillators.
Periodic oscillations observed in swirling flows with and without combustion
Gouldin, F. C.; Halthore, R. N.; Vu, B. T.
1985-01-01
Data obtained by laser induced Rayleigh scattering and hot-wire anemometry are used to study periodic oscillations in swirling flows with and without combustion present. Power spectral density functions reveal the presence of energetic, periodic oscillations in the flow. A band of low frequency oscillations (25-100 Hz) is observed on and near the centerline in the presence of a recirculation zone and is attributed to axial oscillations of the recirculation zone which are amplified with combustion by an interaction between the mechanism for flow recirculation and flow changes induced by combustion. High frequency oscillations between 300-500 Hz are observed in an annular region located in the vortex core. A stability analysis is performed, and it is concluded that these oscillations are most likely helical waves resulting from hydrodynamic instability in the vortex core upstream of the test section.
Combined limit on $B^0_s$ oscillation frequency
Moser, H G
1996-01-01
Several techniques were used in ALEPH to search for B0_s oscillations: Dileptons, lepton-jet charge, kaon-lepton correlation, D_s-lepton and D_s-hadron events with multiple initial state tags. In order to achieve the highest sensitivity all these analyses can be combined. This combination is performed using the amplitude-fit technique. In each analysis the amplitude of the B0_s B0_s/bar oscillation is fitted as function of the oscillation frequency. This amplitude parameter should be 0, if no oscillation is observed, or one if an oscillation signal is present. Oscillations can be excluded for a certain frequency if A = 1 can be excluded. The individual amplitude spectra represent measurements of the same physical quantity and can be combined using straightforeward error propagation. The combined lower limit will be presented.
Effect of boundary on controlled memristor-based oscillator
Fouda, Mohamed E.
2012-10-01
Recently, the applications of memristors have spread into many fields and especially in the circuit theory. Many models have been proposed for the HP-memristor based on the window functions. In this paper, we introduce a complete mathematical analysis of the controlled reactance-less oscillator for two different window functions of Joglekar\\'s model (linear and nonlinear dopant drift) to discuss the effect of changing the window function on the oscillator\\'s behavior. The generalized necessary and sufficient conditions based on the circuit elements and control voltages for both the linear and nonlinear models are introduced. Moreover, closed form expressions for the oscillation frequency and duty cycle are derived for these models and verified using PSPICE simulations showing an excellent matching. Finally a comparison between the linear and nonlinear models which shows their effect on the oscillation frequency and conditions of oscillation is introduced. © 2012 IEEE.
The free energy cost of accurate biochemical oscillations
Cao, Yuansheng; Ouyang, Qi; Tu, Yuhai
2015-01-01
Oscillation is an important cellular process that regulates timing of different vital life cycles. However, in the noisy cellular environment, oscillations can be highly inaccurate due to phase fluctuations. It remains poorly understood how biochemical circuits suppress phase fluctuations and what is the incurred thermodynamic cost. Here, we study four different types of biochemical oscillations representing three basic oscillation motifs shared by all known oscillatory systems. We find that the phase diffusion constant follows the same inverse dependence on the free energy dissipation per period for all systems studied. This relationship between the phase diffusion and energy dissipation is shown analytically in a model of noisy oscillation. Microscopically, we find that the oscillation is driven by multiple irreversible cycles that hydrolyze the fuel molecules such as ATP; the number of phase coherent periods is proportional to the free energy consumed per period. Experimental evidence in support of this un...
Random-matrix-theory approach to mesoscopic fluctuations of heat current
Schmidt, Martin; Kottos, Tsampikos; Shapiro, Boris
2013-08-01
We consider an ensemble of fully connected networks of N oscillators coupled harmonically with random springs and show, using random-matrix-theory considerations, that both the average phonon heat current and its variance are scale invariant and take universal values in the large N limit. These anomalous mesoscopic fluctuations is the hallmark of strong correlations between normal modes.
Oscillating hysteresis in the q-neighbor Ising model.
Jȩdrzejewski, Arkadiusz; Chmiel, Anna; Sznajd-Weron, Katarzyna
2015-11-01
We modify the kinetic Ising model with Metropolis dynamics, allowing each spin to interact only with q spins randomly chosen from the whole system, which corresponds to the topology of a complete graph. We show that the model with q≥3 exhibits a phase transition between ferromagnetic and paramagnetic phases at temperature T*, which linearly increases with q. Moreover, we show that for q=3 the phase transition is continuous and that it is discontinuous for larger values of q. For q>3, the hysteresis exhibits oscillatory behavior-expanding for even values of q and shrinking for odd values of q. Due to the mean-field-like nature of the model, we are able to derive the analytical form of transition probabilities and, therefore, calculate not only the probability density function of the order parameter but also precisely determine the hysteresis and the effective potential showing stable, unstable, and metastable steady states. Our results show that a seemingly small modification of the kinetic Ising model leads not only to the switch from a continuous to a discontinuous phase transition, but also to an unexpected oscillating behavior of the hysteresis and a puzzling phenomenon for q=5, which might be taken as evidence for the so-called mixed-order phase transition.
Collective modes of coupled phase oscillators with delayed coupling
Ares, Saúl; Morelli, Luis G.; Jörg, David J.; Andrew C. Oates; Jülicher, Frank
2012-01-01
We study the effects of delayed coupling on timing and pattern formation in spatially extended systems of dynamic oscillators. Starting from a discrete lattice of coupled oscillators, we derive a generic continuum theory for collective modes of long wavelength. We use this approach to study spatial phase profiles of cellular oscillators in the segmentation clock, a dynamic patterning system of vertebrate embryos. Collective wave patterns result from the interplay of coupling delays and moving...
Energy substrates that fuel fast neuronal network oscillations
Directory of Open Access Journals (Sweden)
Lukas V. Galow
2014-12-01
Full Text Available Fast neuronal network oscillations in the gamma-frequency band (30-100 Hz provide a fundamental mechanism of complex neuronal information processing in the hippocampus and neocortex of mammals. Gamma oscillations have been implicated in higher brain functions such as sensory perception, motor activity and memory formation. The oscillations emerge from precise synapse interactions between excitatory principal neurons such as pyramidal cells and inhibitory GABAergic interneurons, and they are associated with high energy expenditure. However, both energy substrates and metabolic pathways that are capable to power cortical gamma oscillations have been less defined. Here, we investigated the energy sources fueling persistent gamma oscillations in the CA3 subfield of organotypic hippocampal slice cultures of the rat. This preparation permits superior oxygen supply as well as fast application of glucose, glycolytic metabolites or drugs such as glycogen phosphorylase inhibitor during extracellular recordings of the local field potential. Our findings are: (i gamma oscillations persist in the presence of glucose (10 mmol/L for greater than 60 minutes in slice cultures while (ii lowering glucose levels (2.5 mmol/L significantly reduces the amplitude of the oscillation. (iii Gamma oscillations are absent at low concentration of lactate (2 mmol/L. (iv Gamma oscillations persist at high concentration (20 mmol/L of either lactate or pyruvate, albeit showing significant reductions in the amplitude. (v The breakdown of glycogen significantly delays the decay of gamma oscillations during glucose deprivation. However, when glucose is present, the turnover of glycogen is not essential to sustain gamma oscillations. Our study shows that fast neuronal network oscillations can be fueled by different energy-rich substrates, with glucose being most effective.
Novel Hyperbolic Homoclinic Solutions of the Helmholtz-Duffing Oscillators
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Yang-Yang Chen
2016-01-01
Full Text Available The exact and explicit homoclinic solution of the undamped Helmholtz-Duffing oscillator is derived by a presented hyperbolic function balance procedure. The homoclinic solution of the self-excited Helmholtz-Duffing oscillator can also be obtained by an extended hyperbolic perturbation method. The application of the present homoclinic solutions to the chaos prediction of the nonautonomous Helmholtz-Duffing oscillator is performed. Effectiveness and advantage of the present solutions are shown by comparisons.