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The paper reviews some parts of classical potential theory with applications to two-dimensional fluid dynamics, in particular vortex motion. Energy and forces within a system of point vortices are similar to those for point charges when the vortices are kept fixed, but the dynamics is different in the case of free vortices. Starting from Euler’s and Bernoulli’s equations we derive these laws. Letting the number of vortices tend to infinity leads in the limit to considerations of equilibrium distributions, capacity, harmonic measure and many other notions in potential theory. In particular various kinds of Green functions have a central role in the paper, and we make a distinction between electrostatic and hydrodynamic Green functions. We also consider the corresponding concepts in the case of closed Riemann surfaces provided with a metric. From a canonically defined monopole Green function we rederive much of the classical theory of harmonic and analytic forms on Riemann surfaces. In the final section of the paper we return to the planar case, which then reappears in the form of a symmetric Riemann surface, the Schottky double. Bergman kernels, electrostatic and hydrodynamic, come up naturally as well as other kernels, and associated to the Green function there is a certain Robin function which is important for vortex motion, and which also relates to capacity functions in classical potential theory.

Recently, the research on the propagation of hot events has received widespread attention. By analyzing the data of hot events and the data of the common events in the same period on the network, we found that hot events usually break out quickly and opinion leaders and cluster behaviors exist in their propagation process. At the same time, the media public opinion fields of reporting hot events overlap and promote each other. Based on the common factors that drive an event to become a hot event, we used the heat calculation formula and entropy method to put forward the propagation model of hot events based on information coupling and information energy interaction. In the model, the coupling values of different event information are quantified based on the information fragment coupling effect. The heat calculation formula is used to dynamically adjust the propagation probability of different individuals in the propagation process of hot event, and the sensational effect threshold is introduced based on the overall energy value of the event. Finally, we used the real social relationship networks to simulate the evolution propagation process of the hot events, and compared it with the crawling real propagation curve of the events. The proposed model provides a good supplement for the study of the hot events.

The ground state of semiconductor quantum rings (QRs) in the presence of an external magnetic field B is theoretically analyzed. By numerically diagonalizing the effective-mass Hamiltonian of the QRs, the energy and wavefunction of the ground state are obtained. It is found that the energy oscillates as B increases. The evolution of the angular momentum L₀ and the spin S₀ of the ground state in accord with B is revealed. We depict the geometric configuration of the ground state via density functions. Based on an analysis of the wavefunction, it is shown that each configuration is accessible only to a specific group of states having specific L₀ and S₀.

In this work, spectra of energy and fluence of neutrons produced in the conditions of deformed space-time (DST), due to the violation of the local Lorentz invariance (LLI) in the nuclear interactions are shown for the first time. DST-neutrons are produced by a mechanical process in which AISI 304 steel bars undergo a sonication using ultrasounds with 20 kHz and 330 W. The energy spectrum of the DST-neutrons has been investigated both at low (less than 0.4 MeV) and at high (up to 4 MeV) energy. We could conclude that the DST-neutrons have different spectra for different energy intervals. It is therefore possible to hypothesize that the DST-neutrons production presents peculiar features not only with respect to the time (asynchrony) and space (asymmetry) but also in the neutron energy spectra.

HIGHLIGHTS

• •Effectiveness of vice blades flow control method.
• •Improvement mechanism of flow control method on centrifugal pump.
• •Energy redistribution of multi-scale turbulence by flow control method.
• •Design strategy for high-performance centrifugal pump.

The demand for the high-performance centrifugal pumps has grown considerably in order to address various working conditions and application scenarios. Here, a high-performance centrifugal pump capable of great hydraulic and anti-cavitation performance, and low-pressure pulsation and vibration, is realized by adding drainage vice blade to the conventional blade type. The multi-scale turbulence in centrifugal pumps is characterized by the Hybrid RANS/LES method, then the energy distributions are obtained by the proper orthogonal decomposition (POD) method. The experimental methods are employed to study the pressure pulsation and vibration characteristics. The new-type of blades can reconstruct the energy of multi-scale turbulence in centrifugal pump by concentrating the energy on low-frequency large-scale flow structures, while reducing the energy of high-frequency small-scale flow structures. A higher energy of large-scale flow structures can enhance the energy transportation and hydraulic performance in centrifugal pump. The small-scale flow structures with lower energy can suppress high-frequency excitation in flow to avoid the hydraulic resonance, which is essential to improve the dynamic characteristics of the centrifugal pumps. We propose a flow control method that can reconstruct the energy distribution of multi-scale turbulence which can greatly improve its overall performance, suggesting a broad range of promising applications.

In the current era, entire global economies are transitioning to sustainable development because of global warming and climate change. Due to turbulence in environmental issues such as weather shocks, climate change and basic infrastructure and industrial planning, many countries are changing their approach and taking green steps. This paper assesses sustainable finance in India and the ways in which India can mitigate climate changing risk toward zero carbon policy and supporting SDGs 2030. It talks about the physical and transitional climate risks in India like surface temperature, heat wave concourse, etc., and provides a comprehensive analysis of how the corporate sector is imparting its role in sustainable nature through corporate social responsibility (CSR). India is an emerging economy where energy is an essential component. This study analyzes about supply of energy and how India is shifting from traditional energy sources to renewal energy sources.

Thus, the objective of this study is to focus on the initiatives taken by the Indian government for sustainable finance through green bond policy at national and international platforms using the Panchamrit framework adopted by India thereby focusing on India’s sustainable policy support for SDGs 2030. Also, this research proposes numerous recommendations for future sustainable finance research in the context to India, which includes developing and diffusing innovative sustainable financing instruments, magnifying, and managing the profitability and returns of sustainable financing, making sustainable finance more sustainable, and leveraging the power of new-age technologies for sustainable finance.

The possibility of building a quantum computer is critically analyzed. The main point is that the general state of the hypothetical quantum computer with N qubits is characterized by 2^N quantum amplitudes, which are complex numbers restricted by the normalization condition only. It looks highly improbable that it will ever be possible to keep under our control this number of complex parameters even for modest values of $N\sim$ 50 or 100.

This paper investigates the multi-dimensional risk spillover effects of carbon markets with energy, non-energy commodity and stock markets in China before and after the COVID-19 outbreak, through the DY network with GARCHSK-VaR method. The empirical results denote that the total bidirectional risk spillovers of carbon markets become larger after the COVID-19 outbreak than before the COVID-19 outbreak. Interestingly, in both periods, energy is the largest risk contributor to carbon markets, while carbon markets become the net risk contributors to stock markets under COVID-19. Furthermore, compared with Guangdong pilot, the impacts of Hubei pilot on other markets are stronger in both periods. Finally, the dynamic risk spillover effects have obvious differences between before and after the COVID-19 outbreak.