Validating Experiment for the Reaction H2 + NH2- by Dynamical Computations on an Accurate Full-Dimensional Potential Energy Surface

Ion-neutral molecular reactions play key roles in the field of ion related chemistry. As a prototypical multi-channel ion-molecular reaction, the reaction H2 + NH2- → NH3 + H- has been studied for decades. In this work, we develop a globally accurate potential energy surface (PES) for the title system H2 + NH2- based on nearly hundreds of thousands points over a wide dynamically relevant region. The permutational invariants polynomials neural network (PIP-NN) method is used for fitting and the total root mean squared error (RMSE) is extremely small, only 0.026 kcal mol-1. Extensive dynamical and rate coefficient calculations are carried out on this new PIP-NN PES by the quasi-classical trajectory (QCT) method. The calculated rate coefficients for H2 / D2 + NH2- agree well with the experimental results that show a inverse temperature dependence from 50 to 300 K, consistent with the capture nature of this barrierless reaction. A significant kinetic isotope effect has been well reproduced by the QCT computations. In addition, we report a unique phenomenon of significant reactivity suppression by exciting the rotational mode of H2, particular at low collision energies. Further analysis shows that the excitation of rotational mode of H2 would prevent the formation of the reactant complex and thus suppress reactivity.

Hurricane dynamics and rapid intensification via dynamical systems indicators

<p>Although the lifecycle of hurricanes is well understood, it is a struggle to represent their dynamics in numerical models, under both present and future climates. We consider the atmospheric circulation as a chaotic dynamical system, and show that the formation of a hurricane corresponds to a reduction of the phase space of the atmospheric dynamics to a low-dimensional state. This behavior is typical of Bose-Einstein condensates. These are states of the matter where all particles have the same dynamical properties. For hurricanes, this corresponds to a "rotational mode" around the eye of the cyclone, with all air parcels effectively behaving as spins oriented in a single direction. This finding paves the way for new parametrisations when simulating hurricanes in numerical climate models.</p>

Mode specific dynamics in multichannel reaction NH+ + H2

The vibrational and rotational mode specificity of the multichannel NH+ + H2 reaction is studied on a recently constructed ab initio based global potential energy surface using an initial state...

The application of vibrational-rotational operation mode in vibratory drive

In this paper an analysis of the resultant flux linkage vector ψ0 of double-way feed motor (DFM) ​​in the vibrational-rotational mode is shown. It is used for vibration-based diagnostics of various equipment with AC drives. In the case of using DFM in the vibrational-rotational mode the accuracy of motion law implementation is higher than using the standart induction motor. The results of research obtained with the help of a mathematical model of the DFM that allows to explore the special operating modes such as oscillating, polyharmonical, vibrational-rotational and creeping speed ones. The urgency of DFM operational mode and its practical significance as a method of control for vibration-based diagnostics systems are also given herein. The influence of the load parameters on the dynamic parameters of the executive vibratory drive is shown.

Acoustic Investigation of Textile Fabrics

Why is it possible to distinguish between different textile fabrics by just touching them and moving your hand over them and listening to the sound? Particularly for high-quality woven fabrics, e.g. used for tailor-made suits, it is quite common that the dressmaker listens to the sound as their hand rubs the fabric. Can this approach be translated into a technical measurement? What could a sound analysis tell us about the fabric properties? As a first simple approach, we used a record player to rotate different cotton fabrics, and tested fine tips from diverse materials, such as plastic pipettes, pens, glass tips, etc. Our results show clear differences between the textile fabrics, which can be attributed to different yarn, knitted or woven structures. While the rotational mode of investigation impedes fully automated fast Fourier transform (FFT) evaluations, our first results suggest de¬veloping this promising method further.

Characteristics of Atmospheric Kinetic Energy Spectra during the Intensification of Typhoon Lekima (2019)

The intensification of Typhoon Lekima (2019) is simulated with the Weather Research and Forecasting model to study the atmospheric horizontal kinetic energy (HKE) spectra and corresponding spectral HKE budgets under the control of real tropical cyclone (TC). The results show that the TC has the ability to modify the canonical atmospheric energy spectrum during its evolution, which is dominated by its rotational mode. With the intensification of Lekima, the HKE spectrum in the troposphere swells over the central mesoscale and develops an arc-like shape. The stronger the TC, the more pronounced the arc-like shape is and the smaller scale it extends to. The roles various physical processes play at different heights and horizontal scales during the intensification of Lekima are investigated and the dependence of the effect of physical processes on scale and height is revealed. Meanwhile, the potential relationship between the intensification of TC, the activation of energy activity at smaller scales, and the downscale extension of the arc-like spectral shape is found.