Motion Magnification in Solar Imaging Data Sequences in the Sub-pixel Regime

The capability of the motion-magnification technique for the detection of transverse oscillations, such as kink oscillations of solar coronal loops observed with an imaging telescope, in the sub-pixel regime is investigated. The technique is applied to artificial-image sequences imitating harmonic transverse displacements of the loop, observed in the optically thin regime. Motion magnification is found to work well on the analysis of sub-pixel, $\geq 0.01$ ≥ 0.01 pixel oscillations, and it is characterised by linear scaling between the magnified amplitude and input amplitude. Oscillations of loops with transverse density profiles of different steepness are considered. After magnification, the original transverse profiles are preserved sufficiently well. The motion-magnification performance is found to be robust in noisy data, for coloured noise with spectral indices ranging from 0 to 3, and additional Poisson noise with a signal-to-background-noise ratio down to unity. Our findings confirm the reliability of the motion-magnification technique for applications in magnetohydrodynamic seismology of the solar corona.

Dynamic acceleration response of a rock slope with a horizontal weak interlayer in shaking table tests

The weak interlayer in a rock slope often plays a significant role in seismic rockslides; however, the effect of weak interlayer on the seismic slope response and damage process is still not fully understood. This study presents a series of shaking test tests on two model slopes containing a horizontal weak interlayer with different thicknesses. A recorded Wenchuan earthquake ground motion was scaled to excite the slopes. Measurements from accelerometers embedded at different elevations of slope surface and slope interior were analyzed and compared. The effect of the weak interlayer thickness on the seismic response was highlighted by a comparative analysis of the two slopes in terms of topographic amplification, peak accelerations, and deformation characteristics as the input amplitude increased. It was found that the structure deterioration and nonlinear response of the slopes were manifested as a time lag of the horizontal accelerations in the upper slope relative to the lower slope and a reduction of resonant frequency and Fourier spectral ratio. Test results show that under horizontal acceleration, both slopes exhibited significant topographic amplification in the upper half, and the difference in amplification between slope face and slope interior was more pronounced in Slope B (with a thin weak interlayer) than in Slope A (with a thick weak interlayer). A four-phased dynamic response process of both slopes was observed. Similar deformation characteristics including development of strong response zone and macro-cracks, vertical settlement, horizontal extrusion and collapse in the upper half were observed in both slopes as the input amplitude increased; however, the deformations were more severe in Slope B than in Slope A, suggesting an energy isolation effect of the thick interlayer in Slope A.

Frequency-Adaptable Tuned Mass Damper Using Metal Cushions

A frequency-adaptable tuned mass damper (FATMD) using metal cushions as tuneable stiffness components is presented. The dynamic properties of the cushions with respect to stiffness and damping are investigated experimentally in this context. The natural frequency of the experimental FATMD is found to be dependent on the precompression of the metal cushions, which behave like nonlinear springs, yielding an adjustable frequency range from 67 to 826 Hz. As the precompression is increased, the stiffness increases while the damping characteristics decrease, the effect of which was quantified using a viscous mass damper model as a first approximation. Measurements have been carried out under five different excitation amplitudes to investigate the amplitude dependency of the resonance frequency. The FATMD was largely unaffected by changes in input amplitude. It was concluded that metal cushions show great potential for use in FATMDs, surpassing the utility of elastomers, especially with respect to their temperature stability.

Biomechanical properties of a buzz-pollinated flower

Approximately half of all bee species use vibrations to remove pollen from plants with diverse floral morphologies. In many buzz-pollinated flowers, these mechanical vibrations generated by bees are transmitted through floral tissues, principally pollen-containing anthers, causing pollen to be ejected from small openings (pores or slits) at the tip of the stamen. Despite the importance of substrate-borne vibrations for both bees and plants, few studies to date have characterized the transmission properties of floral vibrations. In this study, we use contactless laser vibrometry to evaluate the transmission of vibrations in the corolla and anthers of buzz-pollinated flowers of Solanum rostratum , and measure vibrations in three spatial axes. We found that floral vibrations conserve their dominant frequency (300 Hz) as they are transmitted throughout the flower. We also found that vibration amplitude at anthers and petals can be up to greater than 400% higher than input amplitude applied at the receptacle at the base of the flower, and that anthers vibrate with a higher amplitude velocity than petals. Together, these results suggest that vibrations travel differently through floral structures and across different spatial axes. As pollen release is a function of vibration amplitude, we conjecture that bees might benefit from applying vibrations in the axes associated with higher vibration amplification.

Research on an Electromagnetic Actuator for Vibration Suppression and Energy Regeneration

This paper proposes an electromagnetic actuator that concurrently realizes two working functions of vibration suppression and energy regeneration. The actuator consists of four permanent magnetic rings, three soft iron rings, three coils, and three springs. The design of the electromagnetic actuator is based on finite element method (FEM) analysis, and the prototype is based on this analysis. Based on the prototype, the characteristics of the electromagnetic actuator, which has an output force–current coefficient of 39.49 N/A, are explored. A control algorithm with a position controller and an acceleration controller are applied to the actuator. When an impulse excitation is input to the electromagnetic actuator, the acceleration of the controlled object decreases from 114.26 m/s2 to 3.14 m/s2 here. Moreover, when the sinusoidal excitation with a 3 mm amplitude and 5 Hz frequency is input to the electromagnetic actuator, the vibration amplitude of the controlled object is 0.045 mm, suppressed within 1.46% when compared with the input signal. The peak value of the regenerated electromotive force is 1.97 V here, and the actuator efficiency for regenerating energy is 11.59%. The experimental results with multiple frequencies and amplitudes also show that the amplitude of the controlled object can be suppressed within 5.5%, and that the ratio of the electromotive force (EMF) to the input amplitude is 0.13. The results indicate that this electromagnetic actuator can suppress vibrations effectively and regenerate energy from vibrations.

Nonlinear Dynamics of a Duffing-Like Negative Stiffness Oscillator: Modeling and Experimental Characterization

In this paper, a negative stiffness oscillator is modelled and tested to exploit its nonlinear dynamical characteristics. The oscillator is part of a device designed to improve the current collection quality in railway overhead contact lines, and it acts like an asymmetric double-well Duffing system. Thus, it exhibits two stable equilibrium positions plus an unstable one, and the oscillations can either be bounded around one stable point (small oscillations) or include all the three positions (large oscillations). Depending on the input amplitude, the oscillator can exhibit linear and nonlinear dynamics and chaotic motion as well. Furthermore, its design is asymmetrical, and this plays a key role in its dynamic response, as the two natural frequencies associated with the two stable positions differ from each other. The first purpose of this study is to understand the dynamical behavior of the system in the case of linear and nonlinear oscillations around the two stable points and in the case of large oscillations associated with a chaotic motion. To accomplish this task, the device is mounted on a shaking table and it is driven with several levels of excitations and with both harmonic and random inputs. Finally, the nonlinear coefficients associated with the nonlinearities of the system are identified from the measured data.

Analisis dan Pengukuran Tanggapan Frekuensi terhadap Redaman Serat Optik

The concept of smart home and cyber home is not the same, even much different. If a smart home or smart home is more aimed at users or home users who lead to conventional homes equipped with digital devices, the concept of cyber home is more to the bandwidth capacity of the internet to complement digital devices in the home. For this reason, Cyber Park Indonesia cooperates with PT Wika Realty. Specifically to develop the housing as a cyber home, Cyber Park Indonesia uses optical fiber. [Kompas, 2017]. This fact states that communication using optical fiber becomes very important so that to optimize the optical fiber system, a study that produces frequency responses to optical fiber attenuation parameters is made. Various sine signal frequency and amplitude values are given as input from an optical fiber dispersing system by looking at the response of the receiver in the form of voltage parameter values. The frequency values given range from 100 Hz to 10 Khz. The linkage of the input amplitude value to the damping value is an output voltage output generated by the amplitude of the amplitude parameter at the sending end. This voltage value comparison is used as the damping parameter of an optical fiber communication system. Giving this frequency will provide the performance of a fiber optic communication system. The resulting voltage value is a constant of changes in the frequency value.

High Resolution Impedance Inversion

ABSTRACTThe identification of clay-rich layers is crucial for development of pre-salt reservoirs. They represent flow barriers and compromise the return of investment of the project if the thickness is misvalued. This issue becomes more relevant for thin clay-rich layers. The solution for the characterization of thin beds is classic: increase of the frequency bandwidth in seismic data. Here, we present a new methodology to derive high-frequency impedance volume. The approach starts with the recovery of low and high-frequency components in seismic data by the application of interactive deconvolution (iterdec). The extended bandwidth data is employed as an input amplitude data to the sparse-spike inversion. The outcome is a high-frequency acoustic impedance volume, which improves the interpretation of thin clay-rich layers. We present a study case of a presalt reservoir to demonstrate that this technique mitigated the location risk of an injection well and helped to maximize the oil swept of its vicinity. Furthermore, we discuss the required adaptations in the sparse-spike inversion workflow, and present the advantages of this approach when compared with conventional inversion results.Keywords: Inversion, resolution, broadband, pre-salt. RESUMOA identificação de camadas argilosas é crucial para o desenvolvimento de reservatórios do pre-sal. Elas atuam como barreira para o fluxo dos fluidos, comprometendo o retorno do investimento no projeto, caso sua espessura seja subavaliada. Esta questão se torna mais relevante no caso the camadas argilosas de pequena espessura. A solução para a caracterização de camadas finas é clássica: torna-se necessário aumentar a banda espectral do dado sísmico. O presente trabalho apresenta a metodologia e os primeiros resultados da incorporação de uma nova metodologia para geração de volumes de impedância de alta resolução. Nesta abordagem, os componentes de baixa e alta frequência do dado sísmico são recuperados através da aplicação de um processo de deconvolução iterativa (iterdec). Em seguida, este dado com banda espectral expandida é utilizado como entrada para uma inversão esparsa, resultando num volume de impedância acústica, que reduz as incertezas na interpretação de camadas argilosas de pouca espessura. Apresenta-se o estudo de caso de um reservatório do pre-sal para demonstrar a efetividade desta técnica na mitigação de risco associado ao posicionamento de um poço injetor, resultando na maximização da varredura de óleo em torno do poço. São apresentadas e discutidas as adaptações necessárias ao fluxo tradicional de inversão e condicionamento de dados sísmicos, bem como as vantagens da aplicação dessa metodologia sobre os resultados da inversão.Palavras-chave: Inversão, resolução, banda-larga, pre-sal.