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In the present work we use the contiuum model to study the dynamic behavior of the oscillator array when an injection signal having a time dependent frequency is applied for modulation purposes.
The ICARUS collaboration has completed a search for muon-neutrino disappearance in the context of the 3+1 sterile neutrino model using data collected with the Booster Neutrino Beam at Fermilab during 2022-2023 (ICARUS Run 2). Events are reconstructed with two different reconstruction frameworks and we select events with 1 muon, at least 1 proton, and no pions in the final state. A new fitting framework, called PROfit, was developed for this analysis and used for the final results presented here. As a single detector oscillation search this analysis is systematics limited, but the tools shown here will serve as a building block for future SBN searches where systematics will be constrained by the addition of a near detector. I will discuss the details of the analysis with a focus on the fitting framework, mock data studies, and the final fitting procedure during the data unboxing.
The ICARUS collaboration has completed a search for muon-neutrino disappearance in the context of the 3+1 sterile neutrino model using data collected with the Booster Neutrino Beam at Fermilab during 2022-2023 (ICARUS Run 2). Events are reconstructed with two different reconstruction frameworks and we select events with 1 muon, at least 1 proton, and no pions in the final state. A new fitting framework, called PROfit, was developed for this analysis and used for the final results presented here. As a single detector oscillation search this analysis is systematics limited, but the tools shown here will serve as a building block for future SBN searches where systematics will be constrained by the addition of a near detector. I will discuss the details of the analysis with a focus on the fitting framework, mock data studies, and the final fitting procedure during the data unboxing.
The aerodynamics of a biconvex airfoil cascade oscillating in torsion is investigated using the unsteady aerodynamic influence coefficient technique. For subsonic flow and reduced frequencies as large as 0.9, airfoil surface unsteady pressures resulting from oscillation of one of the airfoils are measured using flush-mounted high-frequency-response pressure transducers. The influence coefficient data are examined in detail and then used to predict the unsteady aerodynamics of a cascade oscillating at various interblade phase angles. These results are correlated with experimental data obtained in the traveling-wave mode of oscillation and linearized analysis predictions. It is found that the unsteady pressure disturbances created by an oscillating airfoil excite wind tunnel acoustic modes which have detrimental effects on the experimental data. Acoustic treatment is proposed to rectify this problem.
The aerodynamics of a biconvex airfoil cascade oscillating in torsion is investigated using the unsteady aerodynamic influence coefficient technique. For subsonic flow and reduced frequencies as large as 0.9, airfoil surface unsteady pressures resulting from oscillation of one of the airfoils are measured using flush-mounted high-frequency-response pressure transducers. The influence coefficient data are examined in detail and then used to predict the unsteady aerodynamics of a cascade oscillating at various interblade phase angles. These results are correlated with experimental data obtained in the traveling-wave mode of oscillation and linearized analysis predictions. It is found that the unsteady pressure disturbances created by an oscillating airfoil excite wind tunnel acoustic modes, which have detrimental effects on the experimental results. Acoustic treatment is proposed to rectify this problem.
SNO+ Collaboration reports its second spectral analysis of reactor antineutrino oscillation using 286 ton-yr of new data. The measured energies of reactor antineutrino candidates were fitted to obtain the second-most precise determination of the neutrino mass-squared difference Δ𝑚$^{2}_{21}$=(7.96$^{+0.48}_{ −0.42}$) × 10 −5 eV2. Constraining Δ𝑚$^{2}_{21}$ and sin 2 𝜃 12 with measurements from long-baseline reactor antineutrino and solar neutrino experiments yields Δ𝑚$^{2}_{21}$=(7.58$^{+0.18}_{−0.17}$) × 10 −5 eV 2 and sin 2 𝜃 12 = 0.308 ± 0.013. This fit also yields a first measurement of the flux of geoneutrinos in the Western Hemisphere, with 73$^{+47}_{−43}$ TNU at SNO+.
An oscillation in the OGO-3 roll control channel, resulting from the EP-5 and EP-6 boom motion coupling into the control channel and causing loss of attitude control, is investigated. The study includes (1) an analysis of the OGO-3 and OGO-2 flight data to determine the nature and extent of the roll oscillation phenomena, (2) design analysis of the complete attitude control subsystem (ACS) to evolve changes which would prevent recurrences of the coupled ACS boom oscillation observed on OGO-3, and (3) analog simulations to verify the performance of the design changes selected. Portions of OGO-3 and OGO-2 flight data are illustrated and the major flexible body oscillation are identified. A model of the major flexible appendage dynamics is developed and is shown analytically and through analog simulations to reproduce the OGO-3 oscillation phenomena. The design changes which were found necessary are: a reversal delay logic for the roll reaction wheels, widening of the solar array dead zone from 0.5 to 1.0 deg, and modification of the OPEP control loop to include a filter and stabilizing feedback loops.
An analysis of the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) data is presented to provide a more complete description of the stratospheric 5-year semi-decadal (SD) oscillation (Mayr et al., 2007). The zonal-mean temperature and zonal wind data from the Atmospheric Research R-1 analysis are employed, covering the years from 1962 to 2002 in the altitude range from 10 to 30km. For diagnostic purposes, the data are separated into the hemispherically symmetric and anti-symmetric components, and spectral analysis is applied to identify the signatures of the SD oscillations. Through the synthesis or filtering of spectral features, the SD modulations of the annual oscillation (AO) and quasi-biennial oscillation (QBO) are delineated. In agreement with the earlier findings, the magnitude of the SD oscillation is more pronounced when the 30-month QBO dominates during the years from 1975 to 1995. This is consistent with results from a numerical model, which shows that such a QBO generates the SD oscillation through interaction with the 12-month AO. In the zonal winds, the SD oscillation in the NCEP data is confined to equatorial latitudes, where it modulates the symmetric AO and QBO by about 5 m/s below 30 km. In the temperature data, the effect is also seen around the equator, but it is much larger at polar latitudes where the SD oscillation produces variations as large as 2 K. Our data analysis indicates that the SD oscillation is mainly hemispherically symmetric, and it appears to originate at equatorial latitudes where most of the energy resides.
NOvA is a long-baseline accelerator neutrino experiment with sensitivity to effects beyond the standard three-flavor oscillation framework. In this work, we study invisible neutrino decay within neutrino oscillations in the context of the NOvA experiment and its impact on measurement of the standard three-flavour parameters. Neutrino decay has been implemented in the oscillation probability calculation and validated against the standard no-decay case. Here we present the current status of the analysis, focusing on oscillation probabilities and neutrino event rate predictions including invisible neutrino decay.
The present investigation is concerned with an important class of power conditioning networks, taking into account self-oscillating dc-to-square-wave transistor inverters. The considered circuits are widely used both as the principal power converting and processing means in many systems and as low-power analog-to-discrete-time converters for controlling the switching of the output-stage semiconductors in a variety of power conditioning systems. Aspects of piecewise-linear modeling are discussed, taking into consideration component models, and an equivalent-circuit model. Questions of singular point analysis and state plane representation are also investigated, giving attention to limit cycles, starting circuits, the region of attraction, a hard oscillator, and a soft oscillator.
A quantitative analysis is made of a linear four-step model for photosynthetic molecular oxygen evolution in which each photochemical trapping center or an associated enzyme cycles through five oxidation states. Based on data obtained with isolated chloroplasts, a number of aspects were considered, including the two perturbations which damp the oscillation of the oxygen flash yield in a flash sequence. The kinetics and the mechanism of deactivation was another aspect investigated.
The present analysis of free liquid drops' inviscid oscillations proceeds through solution of Bernoulli's equation to obtain the free surface shape and of Laplace's equation for the velocity potential field. Results thus obtained encompass drop-shape sequences, pressure distributions, particle paths, and the temporal evolution of kinetic and surface energies; accuracy is verified by the near-constant drop volume and total energy, as well as the diminutiveness of mass and momentum fluxes across drop surfaces. Further insight into the nature of oscillations is provided by Fourier power spectrum analyses of mode interactions and frequency shifts.
The analysis of the chordwise load distribution and its sensitivity to the various system parameters represents the next phase of the overall study and is the subject of the present two volume report. The present volume is a compilation of all of the time history response data obtained during the test program previously described. The data have been tabulated in the form of Fourier coefficients for reasons of compactness and for ease by the user to reproduce the unsteady component of the individual pressures and the complete (unsteady plus steady state components) integrated load results. This data volume contains the individual pressure response time histories along the chord followed by the corresponding integrated load results. A further description of these data tables can be found in the text that follows.
Flight-test systems analysis techniques are applied to the case of aircraft automation-induced oscillations(AIO). Emerging technological advancements in flight control automation and artificial intelligence have created a need for evaluating the age-old aerial phenomenon of undesired aircraft oscillations. This paper is an overview on the study of AIO as interactions between human pilot, software engineer, and vehicle dynamics(e.g., latency) with the presence of winds aloft. Flight-test evaluation included a broad, non-comprehensive theory on cyclical and non-cyclical oscillations and a preliminary evaluation of the ecosystem from software engineer, airspace architect, and human test pilot.
The Solar Dynamics Observatory (SDO) was launched on February 11, 2010 from Kennedy Space Center on an Atlas V launch vehicle into a geosynchronous transfer orbit. SDO carries a suite of three scientific instruments, whose observations are intended to promote a more complete understanding of the Sun and its effects on the Earth's environment. After a successful launch, separation, and initial Sun acquisition, the launch and flight operations teams dove into a commissioning campaign that included, among other things, checkout and calibration of the fine attitude sensors and checkout of the Kalman filter (KF) and the spacecraft s inertial pointing and science control modes. In addition, initial calibration of the science instruments was also accomplished. During that process of KF and controller checkout, several interesting observations were noticed and investigated. The SDO fine attitude sensors consist of one Adcole Digital Sun Sensor (DSS), two Galileo Avionica (GA) quaternion-output Star Trackers (STs), and three Kearfott Two-Axis Rate Assemblies (hereafter called inertial reference units, or IRUs). Initial checkout of the fine attitude sensors indicated that all sensors appeared to be functioning properly. Initial calibration maneuvers were planned and executed to update scale factors, drift rate biases, and alignments of the IRUs. After updating the IRU parameters, the KF was initialized and quickly reached convergence. Over the next few hours, it became apparent that there was an oscillation in the sensor residuals and the KF estimation of the IRU bias. A concentrated investigation ensued to determine the cause of the oscillations, their effect on mission requirements, and how to mitigate them. The ensuing analysis determined that the oscillations seen were, in fact, due to an oscillation in the IRU biases. The low frequencies of the oscillations passed through the KF, were well within the controller bandwidth, and therefore the spacecraft was actually following the oscillating biases, resulting in movement of the spacecraft on the order of plus or minus 20 arcsec. Though this level of error met the ACS attitude knowledge requirement of [35, 70, 70] arcsec, 3 sigma, the desire of the ACS and instrument teams was to remove as much of the oscillation as possible. The Kearfott IRUs have an internal temperature controller, designed to maintain the IRU temperature at a constant temperature of approximately 70 C, thus minimizing the change in the bias drift and scale factors of the mechanical gyros. During ground testing of the observatory, it was discovered that the 83-Hz control cycle of the IRU heaters put a tremendous amount of stress on the spacecraft battery. Analysis by the power systems team indicated that the constant charge/discharge on the battery due to the IRU thermal control cycle could potentially limit the life of the battery. After much analysis, the decision was made not to run the internal IRU heaters. Analysis of on orbit data revealed that the oscillations in the IRU bias had a connection to the temperature of the IRU; changes in IRU temperature resulted in changes in the amplitude and period of the IRU biases. Several mitigating solutions were investigated, the result of which was to tune the KF with larger IRU noise assumptions which allows the KF to follow and correct for the time-varying IRU biases.
An analytical procedure based on Navier-Stokes equations was developed for representing unsteady flow patterns around oscillating obstacles. A variational formulation of the Helmholtz vorticity equation was discretized in finite element form and integrated numerically. At each step of the numerical integration the velocity field around the obstacle was determined from the finite element solution of Poisson's equation. The time-dependent boundary conditions around the oscillating obstacle were introduced as external constraints at each time step of the numerical integration. The obtained results for a cylinder and an airfoil were illustrated in the form of streamlines and vorticity and pressure distributions.
Finite element procedures are presented for the numerical solution of transonic flow over lifting and oscillating airfoils based on small disturbance theory. The algorithm is simple and effective in handling the mixed flow problem and, for airfoil in free air, treats the entire flow domain by making use of the far field asymptotic solution. Numerical results are presented and compared with experimental data and those obtained by finite difference relaxation techniques.
In order to compare and assess potential improvements, two control systems were modeled; the original first flight or prototype aircraft system, and a modification of the prototype system, which essentially reduced the overall gain for the takeoff and landing phase. In general, the overall system gain reduction of the modified flight control system was sufficient to avoid lateral pilot-induced oscillation tendencies. Lowering the system gain reduced the tendency to rate saturate, which resulted in correspondingly higher critical pilot gains for the same control input.