Resonance Capture Research Articles

Resonance-Averaged Solar Torque Dynamics for Tumbling Satellites

Observations indicate that the spin states of retired and otherwise defunct satellites are diverse and can change significantly over time. Understanding defunct satellite spin state evolution is important for solar radiation pressure modeling, active debris removal, satellite servicing, and space situational awareness. Research has shown that many defunct satellites in geosynchronous earth orbit (GEO) are primarily driven by solar radiation torques via the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect. Recent exploration of YORP-driven nonprincipal axis tumbling has uncovered rich dynamic behavior, including tumbling cycles, spin–orbit coupling, and tumbling period resonances. Radar and optical observations of the defunct Geostationary Operational Environmental Satellite (GOES) 8 strongly suggest that it has been captured in a tumbling resonance at least once since 2018. Motivated by these findings, we develop a numerical resonance-averaged dynamic model to understand YORP-driven resonance capture, building on our earlier nonresonant averaging framework. This resonance-averaged model illuminates resonance capture mechanisms. Also, by averaging over the satellite’s rotation, this model is roughly 20 times faster to propagate than the full (Euler) dynamics. Overall, this allows for rapid, broad exploration to determine resonance capture durations, spin states changes, and the influence of initial spin rate and resonance order on resonance strength. This resonance-averaged model can be easily applied to other environmental perturbations.

Amorphous cobalt oxide decorated halloysite nanotubes for efficient sulfamethoxazole degradation activated by peroxymonosulfate

In this study, a new hollow nanotube material, 30% Co–CHNTs was prepared by the impregnation–chemical reduction–calcination method. This material can be used as a peroxymonosulfate (PMS) activator to catalyse the degradation of sulfamethoxazole (SMX). The best reaction conditions that correspond to the degradation rate of SMX, up to 97.5%, are as follows: the concentration of SMX is 10 mg L−1, the amount of catalyst is 0.20 g L−1, the dosage is 1.625 mM, and the solution pH is 6.00. X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectrometry (ICP-OES) show that the calcined composites mainly stimulate an increase in the content of bivalent cobalt in PMS and reduce the leaching of cobalt ions after the reaction. Additionally, the 30% Co–CHNTs + PMS reaction system exhibits a reasonable SMX degradation rate in a natural organic matter solution and excellent stability after three repeated experiments. Furthermore, the possible degradation mechanism in the 30% Co–CHNTs + PMS reaction system was analysed through electron paramagnetic resonance (EPR) and free-radical capture experiments, and it was observed that the non-radical degradation of 1O2 plays a leading role in SMX degradation. Finally, according to the nine degradation intermediates detected by liquid chromatography-mass spectrometry (LC–MS), four possible SMX degradation routes were proposed. This study proved that a 30% Co–CHNTs heterogeneous catalyst is easily prepared, inexpensive, and environmentally friendly and has potential application in antibiotic wastewater treatment.

Anisotropy and polarization of x-ray line emissions in the dielectronic recombination of hydrogenlike Fe25+ ions

We present a systematic study of the anisotropy and polarization of x-ray line emissions in $KLL$ dielectronic recombination of hydrogenlike ${\mathrm{Fe}}^{25+}$ ions. For the $KLL$ dielectronic recombination considered, it consists of a resonant electron capture plus a two-step radiative decay. While the anisotropy and polarization of the first-step decay photons are calculated by using the flexible atomic code, those of the second-step decay photons are obtained with two methods, i.e., the formalism of the deorientation factor and density matrix theory. Resonance strengths are presented as well to synthesize the dielectronic satellite line spectra. The synthetic spectra including the correction of anisotropy and polarization effects show better agreement with existing experiments than previous calculations. This indicates that these effects are important for the intensity distribution of the dielectronic satellite lines.

Resonance Capture of Electrons by Molecules near the Threshold of Ionization

Resonance Capture of Electrons by Molecules near the Threshold of Ionization

Nondestructive Quantitative Analysis of Difficult-to-Measure Radionuclides 107Pd and 99Tc.

Considering the expanding demand for nuclear waste management of the spent nuclear fuel materials in near future, a nondestructive analytical scheme applicable to one of the most difficult-to-measure nuclides 107Pd, which emits no decay γ-rays and whose half-life is too long to be decayed out during a human lifetime, was designed. The scheme consists of a sophisticated instrument capable of the detection of γ-rays by Ge detectors coupled with time-of-flight measurement of neutrons and a high-intensity pulsed neutron beam and can simultaneously perform time-of-flight-coupled prompt γ-ray analysis (TOF-PGA) as well as PGA and neutron resonance capture analysis (NRCA). The analytical capability for simulated samples of the Tc-platinum group metals (Tc-PGMs) obtained by the group-partitioning process of spent nuclear fuels, which contain not only 107Pd but also 99Tc and other difficult-to-measure fission products, was evaluated. It was confirmed that although PGA and NRCA can accurately analyze both nuclides in individual, single substances, only TOF-PGA can analyze 107Pd as well as 99Tc in the Tc-PGM-simulated sample. The TOF-PGA measurement technique can be widely used for the nondestructive analysis of 107Pd and 99Tc in nuclear wastes.

Preparation of a Gangue-Based X-type Zeolite Molecular Sieve as a Multiphase Fenton Catalyst and Its Catalytic Performance.

In this study, a series of X-type zeolite molecular sieve catalysts, modified with copper (Cu-X), were prepared by an alkali fusion–hydrothermal synthesis using coal gangue from Inner Mongolia. These catalysts were used in the degradation of the methylene blue dye by a Fenton-like reaction. Characterization results showed that Cu is considered to be present in the surface structure of the zeolite in the form of doped Cu ions and metal oxide. It is believed that Cu2+ is the main active site involved in the Fenton reaction. The X-ray photoelectron spectroscopy (XPS) spectra indicated that Cu2+ and Cu+ coexist in the catalysts and participate together in the Fenton reaction. The degradation of methylene blue by the Cu-X catalysts was investigated to determine the optimal catalytic conditions in terms of six aspects: catalyst dosage, initial solution concentration, initial pH of the solution, H2O2 dosage, copper loading, and reaction temperature. The experimental results showed that CX-1.0 had excellent activity and stability for the degradation and decolorization of the methylene blue dye, which could completely degrade the dye within 90 min, and the total organic carbon removal rate reached as high as 97.8%. Electron spin resonance (ESR) and radical capture experiments showed that •OH played a dominant role in the Fenton-like reaction. Combined with XPS, ESR, and catalytic tests, the redox cycle of Cu+/Cu2+ was found to be accelerating the generation of reactive radicals in the Fenton system.

Методы спектроскопии диссоциативного захвата электронов и теории функционала плотности для моделирования биологической активности производных хиноксалина

The molecules of 2-methylquinoxalin and 2,3-dimethylquinoxalin were studied by mass spectrometry of negative ions of resonant capture of slow (0-15 eV) electrons. These compounds have antimicrobial, antifungal, bactericidal and preservative properties, and are widely used in medicine and the food industry. The average lifetime of molecular negative ions (NI)relative to electron auto-cleavage is measured experimentally. The most probable structures of fragment ions ([M – H]–, formed during the decay of molecular NI, are revealed. Within the framework of the Arrhenius approximation, the value of the adiabatic electron affinity (EAa) was estimated. It is found that the theoretical values of EAa calculated by the B3LYP/6-31+G(d) method with minimal addition of diffuse functions as the difference between the total energies of the neutral molecule and the radical anion correlate with the values of EAa obtained from the experiment.

Historical glass mosaic tesserae: a multi-analytical approach for their characterization

We present a completely non-destructive approach to analyse a set of historical glass mosaic tesserae. Aim of the study is to obtain a qualitative and quantitative characterization of the glass matrix in terms of elements and mineralogical phases. Several non-destructive techniques have been applied like Particle-Induced X-ray Emission, Particle-Induced Gamma-ray Emission, micro-Raman spectroscopy, neutron resonance capture analysis and neutron activation analysis in order to combine different technique strengths and to explore the effect of different range sizes for the analysis. Yet, best practices require the use of combined analysis and different skills. The paradigm of a non-destructive multi-analytical approach is suggested for a comprehensive investigation in non-homogeneous real samples, like historical glass mosaic tesserae.

Resonance Capture for a Mercurian Orbiter in the Vicinity of Sun

In this work, the problem of resonance caused by some gravitational potentials due to Mercury and a third body, namely the Sun, together with some non-gravitational perturbations, specifically coronal mass ejections and solar wind in addition to radiation pressure, are investigated. Some simplifying assumptions without loss of accuracy are employed. The considered force model is constructed. Then the Delaunay canonical set is introduced. The Hamiltonian of the problem is obtained then it is expressed in terms of the Deluanay canonical set. The Hamiltonian is re-ordered to adopt it to the perturbation technique used to solve the problem. The Lie transform method is surveyed. The Hamiltonian is doubly averaged. The resonance capture is investigated. Finally, some numerical simulations are illustrated and are analyzed. Many resonant inclinations are revealed.

Studies on the damping mechanism of shape memory alloy-spring tuned vibration absorber attached to a multi-degree-of-freedom structure

To mitigate the adverse structural responses, an improved version of the traditional tuned vibration absorber has been proposed based on the shape memory alloy spring, referred as the shape memory alloy-spring tuned vibration absorber. The finite element numerical models of the multi-degree-of-freedom structure (e.g., transmission tower) and shape memory alloy-spring tuned vibration absorber are developed by using the commercial software ANSYS, and the nonlinear behavior of the shape memory alloy spring is validated based on a previous experimental study. The damping mechanism of the shape memory alloy-spring tuned vibration absorber attached to a multi-degree-of-freedom structure under seismic excitations is investigated, and the nonlinear hysteretic behavior of the shape memory alloy spring is also discussed. The results show that the proposed damper has a two-stage damping mechanism, and its control performance is remarkable. Because the coupled system response is sensitive to the amplitude level, the optimal configuration of the shape memory alloy-spring tuned vibration absorber can be obtained by parametric analysis. Particularly, because of the nonlinear target energy transfer and transient resonance capture mechanism, the shape memory alloy-spring tuned vibration absorber exhibits stable control ability under different seismic waves, indicating a good stability in vibration control of a multi-degree-of-freedom system.

Ameliorating the positive temperature feedback coefficient for an MSR fueled with transuranic elements

Transuranic (TRU) elements can be used as an alluring fuel in a graphite-moderated Molten Salt Reactor (MSR) with liquid fuel and online reprocessing. However, the positive temperature feedback coefficient (TFC) stemming from the resolvable fission resonances of Pu-239 and Pu-241 at thermal neutron energies should be addressed. The aim of this study is to propose an effective solution to ameliorate the positive TFC, by adding Er-167 into the fuel salt or adjusting the minor actinides (MA) ratio in TRU. Er-167, with a strong capture resonance cross section of about 10,000 barns at 0.5 eV, is one of the most promising poisons. After adding Er-167 into the fuel salt with hectogram scale, the fuel TFC is decreased significantly to below −10 pcm/K and the total TFC to −2 pcm/K correspondingly. Similar to Er-167, some MA isotopes, especially Np-237 (at 0.5 eV) and Am-241 (at 0.3 eV, 0.6 eV and 1.1 eV) reveal significant capture resonance cross sections (>1000 barns). In this way, increasing the MA ratio in TRU is another available approach to obtain a negative TFC. The simulated results show that adjusting the MA ratio up to 50% can ameliorate the TFC efficiently. Combing the negative TFC and the salt solubility limit, only a narrow region of the fuel volume fraction lower than 25% can meet the two requirements, and the eligible region becomes smaller for a lower MA ratio.

A study of the 1/2 retrograde resonance: periodic orbits and resonant capture

We describe the families of periodic orbits in the 2-dimensional 1/2 retrograde resonance at mass ratio 0.001, analyzing their stability and bifurcations into 3-dimensional periodic orbits. We explain the role played by periodic orbits in adiabatic resonance capture, in particular how the proximity between a stable family and an unstable family with a nearly critical segment, associated with Kozai separatrices, determines the transition between distinct resonant modes observed in numerical simulations. Combining the identification of stable, critical and unstable periodic orbits with analytical modeling, resonance capture simulations and computation of stability maps helps to unveil the complex 3-dimensional structure of resonances.

Time-resolved prompt-gamma activation analysis at spallation neutron sources and applications to cultural heritage, security, and radiation protection

The present and future developments of time-resolved prompt-gamma activation analysis (T-PGAA) at pulsed neutron sources is discussed in the framework of the successful history of neutron-activation techniques. A brief description of the state of the art and the most important user facilities using standard prompt-gamma activation analysis (PGAA) is provided. Then, we discuss the challenges and the opportunities for T-PGAA at pulsed neutron sources, and the potential impact for applications to cultural heritage, radiation protection, and security. We notice some inversions of trend needed for the further development of T-PGAA with epithermal and fast neutrons, such as the possibility to use fast and high-efficiency γ-ray scintillators with lower energy resolution (compared to usual high-purity germanium detectors) when the signal from neutron capture resonance is selected. We also suggest how detection systems often used in other fields, such as medical physics, can be of interest and inspiration also in the case of neutron-based investigations. Finally, we present new data of T-PGAA measurements on VESUVIO using neutron energies up to the keV using the scintillators available on the instrument, for samples of gold (of interest in cultural heritage), cadmium (for environmental safety), and tantalum (a material used in biomedical implants).

Measurement of the 72Ge(n,γ) cross section over a wide neutron energy range at the CERN n_TOF facility

The Ge72(n,γ) cross section was measured for neutron energies up to 300keV at the neutron time-of-flight facility n_TOF (CERN), Geneva, for the first time covering energies relevant to heavy-element synthesis in stars. The measurement was performed at the high-resolution beamline EAR-1, using an isotopically enriched GeO272 sample. The prompt capture γ rays were detected with four liquid scintillation detectors, optimized for low neutron sensitivity. We determined resonance capture kernels up to a neutron energy of 43keV, and averaged cross sections from 43 to 300keV. Maxwellian-averaged cross section values were calculated from kT=5 to 100keV, with uncertainties between 3.2% and 7.1%. The new results significantly reduce uncertainties of abundances produced in the slow neutron capture process in massive stars.

Vortex-induced vibration of a cylinder with nonlinear energy sink (NES) at low Reynolds number

Vortex-induced vibration (VIV) is a fluid structure interaction phenomena that can lead to the fatigue failure of high-rise structures. To study the basic principles and method of VIV suppression for a cylinder structure, a two-dimensional simulation model using a cylinder with two degrees of freedom in-line and cross-flow directions is presented herewith. A nonlinear energy sink is added to cylinder structures to assess its impact on vibration suppression. As a result, this study aims to investigate the VIV of cylinder under the action of the NES at low Reynolds numbers. The accuracy of the simulation model is verified by the comparison with the experimental results. Particularly, the VIV response is investigated with different mass ratio $$\beta$$ between the NES and cylinder (namely $$\beta$$ of 0.15, 0.2 and 0.3) at Re = 100 in air environment by analyzing the vibration response, phase diagram, time–frequency and vorticity contours of cylinder and NES oscillator. Three distinct function modes of NES for selected mass ratio $$\beta$$ are also observed. The results indicate that the NES can change between resonance capture states, from weak to strong, when the mass ratio $$\beta$$ increases to a defined value. In this case, the main vibration frequency of the cylinder varies over time, and the motion is in the chaotic state. The NES can also effectively reduce the vibration amplitude in both the in-flow and cross-flow directions.

Tilting Uranus: Collisions versus Spin–Orbit Resonance

Abstract In this paper, we investigate whether Uranus’s 98° obliquity was a by-product of a secular spin–orbit resonance assuming that the planet originated closer to the Sun. In this position, Uranus’s spin precession frequency is fast enough to resonate with another planet located beyond Saturn. Using numerical integration, we show that resonance capture is possible in a variety of past solar system configurations but that the timescale required to tilt the planet to 90° is of the order ∼108 yr—a time span that is uncomfortably long. A resonance kick could tilt the planet to a significant 40° in ∼107 yr only if conditions were ideal. We also revisit the collisional hypothesis for the origin of Uranus’s large obliquity. We consider multiple impacts with a new collisional code that builds up a planet by summing the angular momentum imparted from impactors. Because gas accretion imparts an unknown but likely large part of the planet’s spin angular momentum, we compare different collisional models for tilted, untilted, spinning, and nonspinning planets. We find that a 1 M ⊕ strike is sufficient to explain the planet’s current spin state, but that two 0.5 M ⊕ collisions produce better likelihoods. Finally, we investigate hybrid models and show that resonances must produce a tilt of at least ∼40° for any noticeable improvements to the collision model. Because it is difficult for spin–orbit resonances to drive Uranus’s obliquity to 98° even under these ideal conditions, giant impacts seem inescapable.

Resonant electron capture negative ion mass spectrometry: the state of the art and the potential for solving analytical problems

Resonant electron capture negative ion mass spectrometry: the state of the art and the potential for solving analytical problems

Thymidine and stavudine molecules in reactions with low-energy electrons

The negative ion formation and fragmentation processes in thymidine and stavudine were studied by means of resonant electron capture mass spectrometry in the electron energy range 0–14 eV. Stavudine is a nucleoside analog of thymidine, that differs from the latter by the presence of double bond in the deoxyribose moiety. In the energy range below 5 eV transient negative ions have been found to arise via shape resonances resulting in electron attachment into the empty π*-orbitals. The main fragmentation channels for molecular ions are the H-atom loss and N-glycosidic bond cleavage between sugar and a nucleobase moieties. The dissociative electron attachment cross sections for the fragment negative ions were measured. The structures for some observed anions and neutral counterparts were suggested basing on the thermochemical approach for dissociative reactions energy balance under the support of quantum chemical calculations. The processes of ion formation in thymidine were found to be similar to those revealed previously for deoxyuridine nucleoside. In contrast, very strong dissociative channel was found for stavudine yielding [M–R]– ions (where R is a sugar moiety) in the energy range <3 eV. The efficient fragmentation found for stavudine in the low energy electron attachment reactions may have implications for the design of nucleoside radiosensitizers for cancer therapy.

Suppression of panel flutter response in supersonic airflow using a nonlinear vibration absorber

A nonlinear vibration absorber (NVA) is used to suppress the nonlinear response of a panel flutter in supersonic airflow. The nonlinear aeroelastic equations of a three-dimensional (3-D) panel with an NVA are established using Galerkin’s method, with the aerodynamic load being based on the piston aerodynamic theory. We use the aeroelastic equations to study the nonlinear aeroelastic response behaviors of the 3-D panel with an NVA and then obtain the NVA suppression region. The effects of different NVA parameters on the flutter boundary and the NVA suppression region are examined, and a design technique is developed to find a suitable combination of parameter values to suppress the nonlinear panel flutter response. The results show that the nonlinear aeroelastic responses of the panel are completely suppressed by recurrent transient resonance capture (TRC) and permanent resonance capture (PRC) of the NVA in the NVA suppression region. The phase difference between the transient energy of the panel and the NVA is nearly 180° in PRC. The NVA can suppress the aeroelastic response amplitude of the panel sufficiently only if the transient energy of the panel and NVA are comparable. The NVA parameters can affect the flutter boundaries and the NVA suppression regions with different patterns. The expected suppression response amplitude should be considered in designing the NVA parameters.

Nonlinear normal modes and optimization of a square root nonlinear energy sink

Since the vibration mitigation of nonlinear energy sinks (NESs) needs multi-objective optimization, this paper aims to address this issue with efficient multi-objective particle swarm optimization (MOPSO) methods. A non-polynomial NES model, namely a square root NES (SRNES), is targeted for multi-objective optimization and dynamical analysis on an impulsively excited linear oscillator (LO) and compared with the corresponding polynomial model. Different MOPSO methods are developed to balance the mass and dissipation efficiency of SRNESs by utilizing weighted ranking, external archive, and non-dominated sorting. And nonlinear normal modes (NNMs) are extended for the analysis of SRNESs. The optimization results show the efficient targeted energy transfer (TET) and high robustness of the bistable SRNES in different LO initial and damping conditions. Specifically, more than 95% energy absorption can be easily witnessed, even in a small mass ratio (around 0.003), but the amplitude of the SRNES can be very large. The principal manifestation of the optimal TET is 1:1 resonance capture along with considerable low-frequency components of the SRNES. The optimization results of the SRNESs and the linear vibration absorbers show high similarities, while with a large mass ratio, the SRNESs possess broader range of spring stiffness. In the comparison of the two NES models, the differences are found in potential energy surfaces, NNMs, in-well motion, and vibration attenuation performance. Besides, the SRNESs can be divided into two groups in terms of the conservative dynamics, which can be explained by the polynomial model. The frequency component of in-phase NNMs dominates in the conservative and dissipative dynamics of the SRNESs, which lead to the transition of NNMs in the dissipative dynamics. In summary, the efficient MOPSO methods can be designed for different needs of vibration suppression and structure cost. Furthermore, it is important to directly analyze the non-polynomial nonlinear vibration, because transforming non-polynomial models into polynomial ones may lead to unreasonable or imprecise results. Finally, the NES damping structure and the NES performance in small mass conditions should be enhanced.