Phase transition to chimera state in two populations of oscillators interacting via a common external environment

We consider two populations of coupled oscillators, interacting each other through a common external environment. The external environment is synthesized by the contributions from all oscillators of both populations. Such indirect coupling via an external medium arises naturally in many fields, e.g., dynamical quorum sensing in coupled biological and chemical systems. We analyze the existence and stability of a variety of stationary states on the basis of the OttAntonsen reduction method, which reveals that the interaction via an external environment gives rise to unusual collective behaviors such as the uniform drifting, non-uniform drifting and chimera states. We present a complete bifurcation diagram, which provides the underlying mechanism of the phase transition towards chimera state with the route of incoherence → uniform drift → non-uniform drift → chimera.

A multi-temperature universe can allow a sub-MeV dark photon dark matter

An analysis of sub-MeV dark photon as dark matter is given which is achieved with two hidden sectors, one of which interacts directly with the visible sector while the second has only indirect coupling with the visible sector. The formalism for the evolution of three bath temperatures for the visible sector and the two hidden sectors is developed and utilized in solution of Boltzmann equations coupling the three sectors. We present exclusion plots where the sub-MeV dark photon can be dark matter. The analysis can be extended to a multi-temperature universe with multiple hidden sectors and multiple heat baths.

Co-Simulation by Indirect Coupling of a Brushless Single-Phase Synchronous Generator

This paper describes and simulates the transient process of self-excitation of a single-phase brushless capacitor-exciter synchronous generator (BCESG) by Finite Element Method (FEM). To simul the BCESG the coupling between the magnetic circuit and the electrical circuit the Method of Co-Simulation by Indirect Coupling is applied. The Total Harmonic Distortion of the terminal voltage is calculated and the main harmonics identified by Fast Fourier Transform (FFT).

Performing an Indirect Coupled Numerical Simulation for Capacitor Discharge Welding of Aluminium Components

Capacitor discharge welding (CDW) for projection welding provides very high current pulses in extremely short welding times. This requires a quick follow up behaviour of the electrodes during the softening of the projection. The possibilities of experimental process investigations are strongly limited because of the covered contact zone and short process times. The Finite Element Method (FEM) allows highly resoluted analyses in time and space and is therefore a suitable tool for process characterization and optimization. To utilize this mean of optimization, an indirect multiphysical numerical model has been developed in Ansys Mechanical APDL. This model couples the physical environments of thermal–electric with structural analysis. It can master the complexity of large deformations, short current rise times and high temperature gradients. A typical ring projection has been chosen as the joining task. The selected aluminium alloys are EN-AW-6082 (ring projection) and EN-AW-5083 (sheet metal). This paper presents the investigated material data, the model design and the methodology for an indirect coupling of the thermal–electric with the structural physic. The electrical contact resistance is adapted to the measured voltage in the experiment. The limits of the model in Ansys Mechanical APDL are due to large mesh deformation and decreasing element stiffness. Further modelling possibilities, which can handle the limits, are described.

On the Potential of Time Delay Neural Networks to Detect Indirect Coupling between Time Series

Determining the coupling between systems remains a topic of active research in the field of complex science. Identifying the proper causal influences in time series can already be very challenging in the trivariate case, particularly when the interactions are non-linear. In this paper, the coupling between three Lorenz systems is investigated with the help of specifically designed artificial neural networks, called time delay neural networks (TDNNs). TDNNs can learn from their previous inputs and are therefore well suited to extract the causal relationship between time series. The performances of the TDNNs tested have always been very positive, showing an excellent capability to identify the correct causal relationships in absence of significant noise. The first tests on the time localization of the mutual influences and the effects of Gaussian noise have also provided very encouraging results. Even if further assessments are necessary, the networks of the proposed architecture have the potential to be a good complement to the other techniques available in the market for the investigation of mutual influences between time series.

Refined measurement of SecA-driven protein transport reveals indirect coupling to ATP turnover

The universally conserved Sec system is the primary method cells utilise to transport proteins across membranes. Until recently, measuring the activity – a prerequisite for understanding how biological systems works – has been limited to discontinuous protein transport assays with poor time resolution, or used as reporters large, non-natural tags that interfere with the process. The development of an assay based on a split super-bright luciferase (NanoLuc) changed this. Here, we exploit this technology to unpick the steps that constitute post-translational transport in bacteria. Under the conditions deployed, transport of the model pre-protein substrate proSpy occurs at 200 amino acids per minute with the data best fit by a series of large, ∼30 amino acid, steps each coupled to many (100s) ATP hydrolysis events. Prior to that, there is no evidence for a distinct, rate-limiting initiation event. Kinetic modelling suggests that SecA-driven transport activity is facilitated by the substrate (polypeptide) concentration gradient – in keeping with classical membrane transporters. Furthermore, the features we describe are consistent with a non-deterministic motor mechanism, such as a Brownian ratchet.