Brief communication: Lower-bound estimates for residence time of energy in the atmospheres of Venus, Mars and Titan

The residence time of energy in a planetary atmosphere, τ, which was recently introduced and computed for the Earth's atmosphere (Osácar et al., 2020), is here extended to the atmospheres of Venus, Mars and Titan. τ is the timescale for the energy transport across the atmosphere. In the cases of Venus, Mars and Titan, these computations are lower bounds due to a lack of some energy data. If the analogy between τ and the solar Kelvin–Helmholtz scale is assumed, then τ would also be the time the atmosphere needs to return to equilibrium after a global thermal perturbation.

Achieving High Exciton Utilization with Folded π-Molecules

π-Molecules play important roles in many applications such as organic light emitting devices, photocatalysis, photovoltaics, biosensors and medicine. Very often, high-performance π-conjugated molecules are of great research interest. However, owing to the conflict between the design of efficient π structure (good rigidity and planarity) and efficient π aggregates (minimum face-to-face π effect), it is challenging for traditional planar π or recently emerged twisted π molecules to realize very high exciton utilization in solid state. Herein, we report a new π skeleton, folded π, to achieve high exciton utilization in solids. Folded π-based molecules tend to form molecular packing patterns that are rich in π interactions, favoring the suppression of unfavorable energy dissipation pathways such as molecular thermal perturbation. Meanwhile, the potential face-to-face π effect between planar π is well prevented by the hydrogen atoms around the π planes. As a result of effective packing, all the synthesized π-based molecules show very high exciton utilization in solids.

Brief Communication: Residence Time of Energy in the Atmospheres of Venus, Earth, Mars and Titan

The concept of residence time of energy in a planetary atmosphere τR, recently introduced and computed for the Earth's atmosphere (Osácar et al., 2020), is here extended to the atmospheres of Venus, Mars and Titan. After a global thermal perturbation, τR is the time scale the atmosphere needs to return to equilibrium. The residence times of energy in the atmospheres of Venus, Earth, Mars and Titan have been computed. In the cases of Venus, Mars and Titan, these are mere lower bounds due to a lack of some energy data.

Analysis of Heat Transfer in Particle Velocity Sensor with Three-Wire Configuration

Particle velocity sensor (PVS) plays an important role in determining the type and location of a sound source. In this presentation, analytical model of heat transfer in PVS with a three-wire (SHS) configuration was first presented. By comparing with the thermal diffusion motion, the forced convection exerts a smaller influence on the temperature distribution. Thus, variation in forced convection could induce the formation of a thermal perturbation field. The overall temperature distribution model of a PVS is made up of a steady temperature field and a thermal perturbation field. With the derived model, PVS with SHS configuration has smaller thermal noise and higher signal-to-noise ratio in comparision with a two-wire (SS) configuration under the same conditions. Optimized parameters of structure design and heating power could be obtained via the analysis model. Also, this model gives optimal output performance and frequency-dependent characteristic curve. Numerical results are found to be in good agreement with the analytical solutions and experimental data, which verify the correctness of analytical model and numerical method. The study provides a basis for a theoretical and numerical analysis.