Terahertz meta-chip switch based on C-ring coupling

Terahertz switch is one of the key components of future communication, radar, and imaging systems. Limited by the strong electromagnetic coupling in subwavelength scale, the traditional terahertz switch is difficult to meet the increasing application requirements. In this paper, a parallel topology terahertz meta-chip switch based on the combination of equivalent circuit theory and electromagnetic coupling is proposed. The meta-chip is realized by adjusting the density of two-dimensional electron gas of InP-HEMT, which converts the electromagnetic coupling between the microstructure and microstrips. By using the 90 nm gate length InP-HEMT process, a C-ring loaded meta-chip is fabricated and tested in this paper. The results show an insertion loss lower than 1 dB with a 10 dB switching ratio, which is 20% higher than that without C-ring while ensuring the rather low insertion loss. It shows that the presented mechanism has positive significance for the design of terahertz band functional devices.

Areas Important for Ecological Connectivity Throughout Canada

Governments around the world have acknowledged the importance of conserving ecological connectivity to help reverse the decline of biodiversity. In this study we employed recent methodological developments in circuit theory to conduct the first pan-Canadian analysis of multi-species connectivity for all terrestrial regions of the country, at a spatial grain sufficient to support local land-management decisions. We developed a movement cost surface with a limited number of thematic categories using the most recently updated land cover data available for the country. We divided the country into 17 tiles and used a wall-to-wall, omnidirectional mode of Circuitscape on each tile in order to assess ecological connectivity throughout entire landscapes as opposed to strictly among protected areas. The resulting raw current density map of Canada revealed heterogenous patterns of current density across the country, strongly influenced by geography, natural barriers, and human development. We included a validation analysis of the output current density map with independent wildlife data from across the country and found that mammal and herpetofauna locations were predicted by areas of high current density. We believe our current density map can be used to identify areas important for connectivity throughout Canada and thereby contribute to efforts to conserve biodiversity.

Discussion and Analysis of Dumbbell Defect-Ground-Structure (DB-DGS) Resonators for Sensing Applications from a Circuit Theory Perspective

Microstrip transmission lines loaded with dumbbell defect-ground-structure (DB-DGS) resonators transversally oriented have been exhaustively used in microwave circuits and sensors. Typically, these structures have been modelled by means of a parallel LC resonant tank series connected to the host line. However, the inductance and capacitance of such model do not have a physical meaning, since this model is inferred by transformation of a more realistic model, where the DB-DGS resonator, described by means of a resonant tank with inductance and capacitance related to the geometry of the DB-DGS, is magnetically coupled to the host line. From parameter extraction, the circuit parameters of both models are obtained by considering the DB-DGS covered with semi-infinite materials with different dielectric constant. The extracted parameters are coherent and reveal that the general assumption of considering the simple LC resonant tank series-connected to the line to describe the DB-DGS-loaded line is reasonable with some caution. The implications on the sensitivity, when the structure is devoted to operating as a permittivity sensor, are discussed.

Modeling thermal processes using electrical equivalent circuits in digital twins of technical devices

One of the promising areas of digitalization of the economy today is associated with the concept of digital twins of technical systems. Digital twins based on simulation models of technical devices, which are calibrated according to the results of experimental studies on a real-time device are of great interest. Such models allow us to conduct preventive analysis of the operation consequences of these devices in various modes. Thus, a problem occurs to develop parametrically coupled models of physical processes of various natures that underlie the principles of operation of these devices. Currently, for these purposes, simulation software packages are used. MatLab Simulink software is the most popular one. However, not all such software packages provide tools to work with chain models of all physical processes that are of the user interest. Thus, the purpose of this article is to develop methods to construct digital twins of technical devices using models of arbitrary physical processes (in particular, thermal) based on electrical equivalent circuits. It unifies the task of modeling processes based on circuit theory. To develop the method to construct digital twins, the authors have applied the phenomenon of isomorphism of equations of physical processes based on the theory of circuits that is based on the theory of ordinary differential equations. The simulation has been carried out in the MatLab Simulink environment using the SimScape library for modeling physical processes. Assumptions typical for circuit theory are made during simulation. A method has been developed to construct simulation models based on the use of electrical equivalent circuits of physical processes of an arbitrary nature. In contrast to existing approaches, where the analogy method is used to simulate one of the processes of the researcher interest, it is proposed to develop a single integrated model of all physical processes underlying the operation of this class of devices. It will reduce the level of requirements for simulation systems by limiting the requested functionality of these systems to electrical circuits only. The proposed method can be used as the basis for the development of digital twins of technical devices that allow simulating their operation in arbitrary modes, considering a variety of related factors of different physical nature.