Oscillating Behaviors - A single-axis Microelectromechanical system gravimeter has recently been developed at the University of Glasgow. The sensitivity and stability of this device was demonstrated by measuring the Earth tides. The success of this device was enabled in part by its extremely low resonant frequency. This low frequency was achieved with a geometric anti-spring design, fabricated using well-established photolithography and dry etch techniques. Analytical models can be used to calculate the results of these non-linear oscillating systems, but the power of finite element analysis has not been fully utilised to explore the parameter space before now. In this article finite element models are used to investigate the behaviour of geometric anti-springs. These computer models provide the ability to investigate the effect of the fabrication material of the device: anisotropic \textless100\textgreater crystalline silicon. This is a parameter that is difficult to investigate analytically, but finite element modelling is used to take anisotropy into account. The finite element models are then used to demonstrate the design of a three-axis gravimeter enabling the gravity tensor to be measured - a significantly more powerful tool than the original single-axis device.

Oscillating Behaviors - In this paper, we examine the asymptotic behavior of an equation that describes two rotors installed on a common oscillating platform. Namely, we establish analytic criteria for self-synchronization of the rotors by means of the Popov method of “a priori integral indices”.

Oscillating Behaviors - There is a constant push for ever increasing performance in traditional computing systems, leading to high power consumption and, in the end, to the incapacity of conventional electronics to handle heavy computing tasks, which usually require learning features. Thus, the development of novel nanoelectronic devices with inherent neuromorphic characteristics and a low energy footprint has become a viable alternative. In order to simulate neuromorphic features utilizing memristive devices, the threshold switching effect is critical, which can be seen in the rich dynamics of metallic conductive filament (CF). In this paper, a realistic model of the unipolar nature of CBRAM devices is exploited to create a memristor-based oscillator that can integrate neuromorphic features. Bipolar memristive devices have been used to match the weight of the neurons in a crossbar configuration. The used physical model for these memristors was fitted to fabricated devices in order to achieve the expected accuracy in the circuit simulation. The oscillator’s output signal and behavior matched the theoretical background of biological neurons. Thus, this approach can be considered as the first step towards the development of low-power oscillation-based neuromorphic hardware with biological-like behavior.

Oscillating Behaviors - The majority of space science missions aim to measure weak slow varying electromagnetic fields and in order to do so, need to meet strict cleanliness requirements. The accurate characterization of equipment in the extremely lowfrequency domain (below several hundred kHz) should include the direct emitted electric field as well as the induced behavior of the device due to the unit-to-unit interaction. Following a detailed characterization at the unit level, the unit-to-unit interaction is attributed to the near field scattering effect, usually considering the scatterer as a small sphere. This way the induced behavior of the unit can be described by an oscillating dipole coherent to the incident field. This work highlights the importance of induced behavior of the units at the system level for accurate system predictions in the case that the scatterer can’t be considered as a small sphere due to dielectric materials or complex unit geometry. The authors aim to characterize the induced behavior by solving the inverse electromagnetic scattering problem through a customized measurement procedure.

Oscillating Behaviors - Wave energy converters (WECs) are still at an earlier stage of development when compared to variable renewable energy systems based on wind or solar power. Indeed, only a few WECs have exported power to electric grids until recently. Thus, the development of mathematical models able to represent essential aspects of the system and its connection to the grid becomes fundamental to assess the impact of integrating wave power to grids. This work develops a fully integrated waveto-wire model, where the electrical model has re-configurable dynamic models of rotary and linear generators (with controllers) to accommodate different types of oscillating-body systems. Such an electrical model is interfaced with the WEC hydrodynamic and mechanical models. A complete wave-to-grid model is presented by integrating the generator system model, an electrical grid interface unit and a network equivalent for the receiving grid in a unified simulation environment with the WEC-Sim, an open-source tool for simulating the dynamic behaviour of WECs. Numerical simulation studies are presented considering different operating conditions for the grid integration of a floating body that is connected to either an hydraulic power take-off system or a direct-drive system.

Oscillating Behaviors - Animals successfully perform many behavioral tasks within the framework of a closed-loop sensorimotor control system during their daily lives. To achieve this, animals receive sensory signals from their environment through various sensory receptors and process these signals in their central nervous systems (CNS). Then, using this sensory feedback, animals produce necessary motor signals and transmit them to their muscles to perform the desired behavior. During this process, animals integrate sensory information perceived by different sensory receptors and they simultaneously stimulate multiple muscle combinations. The goal of this study is to identify the closed-loop sensorimotor control processes of animals during their unconstrained behaviors. To achieve this, we built a novel experimental setup that allows data-driven system identification of the target tracking behavior of zebrafish during rheotaxis. In that, a stimulus target oscillating in the frequency range of 0-2 Hz was presented to the zebrafish. Then, frequency response of the target tracking performance for N=5 fish were estimated.

Oscillating Behaviors - This work presents a self-oscillating mixer (SOM) based on a slow-wave structure for phase-noise reduction. Emphasis is placed on the analysis/optimization methods, which include aspects such as conversion gain, nonlinear distortion, and operation boundaries. In a first stage, the parameters of the slowwave structure are optimized to obtain a low phase-noise spectral density. As an example, a structure based on a unit cell containing a Schiffman section is considered. Then, the SOM behavior is addressed through an analytical model that should enable an understanding of its main operation characteristics. A practical FET-based circuit at 2.3 GHz is simulated with some novel harmonic-balance techniques and experimentally characterized.