Characterizing Spectral Channels of Visible Emission Line Coronagraph of Aditya-L1

Aditya-L1 is India’s first solar mission with the Visible Emission Line Coronagraph (VELC), which consists of three spectral channels taking high-resolution spectroscopic observations of the inner corona up to 1.5 Rʘ at 5,303, 7,892, and 10,747 Å. In this work, we present a strategy for the slit width optimization of the VELC using synthetic line profiles by taking into account the instrument characteristics and coronal conditions for log(T) varying from 6 to 6.5. The synthetic profiles are convolved with simulated instrumental scattered light and noise to estimate the signal-to-noise ratio (SNR), which will be crucial to designing the future observation plans. We find that the optimum slit width for VELC turns out to be 50 μm, providing sufficient SNR for observations in different solar conditions. We also analyzed the effect of plasma temperature on the SNR at different heights in the VELC field of view for the optimized slit width. We also studied the expected effect of the presence of a CME on the spectral channel observations. This analysis will help to plan the scientific observations of VELC in different solar conditions.

Insertion loss of periodic cylindrical shells with helical slit

We propose periodic shells with helical slit to overcome the lacuna in periodic C scatterers, where the first Bragg band is considerably reduced on increasing width of the slit. The key discovery of this research indicates that, by changing the upright slit of the C scatterers to helical slits, larger insertion loss (IL) is achieved around the first Bragg band without compromising the local resonance band. Comparing the performance of periodic shells without slit or cylindrical scatterers, it is found that IL becomes larger at first Bragg band. The pitch, thickness of the shell and width of helical slit can be altered to adjust the resonance of the proposed shells. On decreasing the pitch or increasing the slit width, the resonance band shifts toward high frequencies without much alteration in acoustic attenuation of bandwidth. Additionally, below threshold pitch, the said peak merges with first Bragg band and broadens with prominent IL. The calculated band structure authenticates the bandwidth of the first Bragg band, and the additional sharp peak in IL can be attributed to local resonance of the periodic scatterers.

Seismic Behavior of Nonductile RC Frame Slotted with Corrugated Steel Plate Shear Walls

Two specimens of nonductile reinforced concrete (RC) frame (ND-1) and nonductile RC frame retrofitted by corrugated steel plate shear walls slotted with columns (ND-2) are established by finite element. These specimens have same dimensions and steel skeletons. Finite element models had been verified by the existing experimental results. The hysteresis curves, skeleton curves, ductility, and stiffness curves of Specimen ND-1 and Specimen ND-2 are compared. The results show that the reinforcement effect is significant. Twenty-four models are built to study the seismic behavior on different influence parameters. The parameters are slit width, thickness of corrugated steel plate shear walls, concrete strength of nonductile RC frame, and boundary conditions of corrugated steel plate shear walls at slotted parts. The results indicate that the strength is declined with the increase of slit width. With the increase of thickness and concrete strength, the strength and stiffness are enhanced. The strength is larger with the boundary than without. Slit width and thickness have an important impact on the stiffness. Concrete strength and boundary conditions have little impact on stiffness. The strengthened nonductile RC frames have enough ductility.

Experimental Study on Ultrasonic Vibration-Assisted WECDM of Glass Microstructures with a High Aspect Ratio

With the rapid development of micro-electro-mechanical systems (MEMSs), the demand for glass microstructure is increasing. For the purpose of achieving high quality and stable machining of glass microstructures with a high aspect ratio, ultrasonic vibration is applied into the micro-wire electrochemical discharge machining (WECDM), which is proposed as ultrasonic vibration-assisted WECDM with a micro helical electrode. Firstly, the formation of a gas film on the surface of the helical electrode in WECDM machining is simulated, meaning the thickness of the gas film can be reduced by adding suitable ultrasonic amplitude, thus reducing the critical voltage, then the machining localization and stability were enhanced. Then, the micro helical electrode with a diameter of 100 μm is used to carry out sets of experiments that study the influence of ultrasonic amplitude, machining voltage, duty factor, pulse frequency, and feed rate on the slit width. The experimental results show that the machining stability and quality are significantly improved by adding suitable ultrasonic amplitude. When the amplitude was 5.25 μm, the average slit width was reduced to 128.63 μm with a decrease of 20.78%. Finally, with the optimized machining parameters, micro planar coil structure and microcantilever structure with a high aspect ratio were fabricated successfully on the glass plate. It is proved that ultrasonic vibration-assisted WECDM with the micro helical electrode method can meet the requirements of high aspect ratio microstructure machining for hard and brittle materials.

Fractional Young double-slit numerical experiment with Gaussian wavepackets

In the present work, we consider the transmission properties of a Gaussian wavepacket when transmits through few double and multi-slit systems in a fractional medium. For this purpose, we have solved the two-dimensional fractional Schrodinger equation utilizing a split-step Fourier method. Then, we have investigated the effects of different parameters such as the number of slits, slit width, barrier width, layer width, layer heights, fractional order, and wavepacket width on the transmission coefficient, and wavepacket evolution.