Ultra-wideband, wide angle, asymmetric transmission based chiral metasurface for C and X band applications

A multi-layered chiral device manifesting asymmetric transmission (AT) facilitating one-way channeling of electromagnetic (EM) waves, based on the inherent polarization is presented. The designed metasurface depicts a high transmission contrast with an efficiency above 80% for an ultra-wide operational range of 6.3–12.3 GHz, constituting a fractional bandwidth of 64%. As an additional feature, the reported metasurface yields robustness against oblique incidences up to 45$$^\circ $$ ∘ while maintaining high transmission efficiency. This report also introduces a unique analogy of the AT based communication system with logic-gates by formulating its truth-table and logic circuit. Furthermore, new insights of AT magnitude’s dependence to oblique incidences are presented on the account of surface impedance mismatch due to TE and TM polarization with varying incidence angle. Moreover, avoidance of grating lobes and the associated transmission deterioration through utilization of electrically small periodic metasurface is presented. The results have been numerically and practically validated yielding state-of-the-art features. Operating within C and X band, the reported work is an ideal candidate for practical AT applications.

Ultra-wideband, Wide Angle, Asymmetric Transmission based Chiral Metasurface for C and X Band Applications

A multi-layered chiral device manifesting asymmetric transmission (AT) facilitating one-way channeling of electromagnetic (EM) waves, based on the inherent polarization is presented. The designed metasurface depicts a high transmission contrast with an efficiency above 80% for an ultra-wide operational range of 6.3-12.3 GHz, constituting a fractional bandwidth of 64%. As an additional feature, the reported metasurface yields robustness against oblique incidences up to 45◦ while maintaining high transmission efficiency. This report also introduces a unique analogy of the AT based communication system with logic-gates by formulating its truth-table and logic circuit. Furthermore, new insights of AT magnitude’s dependence to oblique incidences are presented on the account of surface impedance mismatch due to TE and TM polarization with varying incidence angle. Moreover, avoidance of grating lobes and the associated transmission deterioration through utilization of electrically small periodic metasurface is presented. The results have been numerically and practically validated yielding state-of-the-art features. Operating within C and X band, the reported work is an ideal candidate for practical AT applications.

Tipping points induced by parameter drift in an excitable low-order model of the wind-driven ocean circulation

<p>A quasi-geostrophic, low-order model of the wind-driven ocean circulation is used to illustrate tipping points induced by time-dependent forcing in excitable chaotic systems. When the wind stress amplitude G is constant in time, our model has a bifurcation from low-amplitude oscillations to high-amplitude relaxation oscillations (ROs) at a wind intensity value G<sub>c</sub>. In the presence of time-dependent wind stress, the corresponding tipping point time t<sub>tp</sub> is defined as the time at which ROs arise. Numerical experiments are carried out using ensemble simulations in the presence of different drift rates of monotonically increasing forcing. Additional experiments include small periodic perturbations of such forcing. The results indicate substantial sensitivity of t<sub>tp</sub> and G(t<sub>tp</sub>) Rate-induced tipping, coexisting pullback attractors and total independence from initial states are found for subsets of parameter space. Besides, nonlinear resonance occurs in the presence of periodic perturbations for periods comparable to the RO time scale. The small periodic perturbation can be thought of as the seasonal-to-interannual variability in the wind stress, while the monotonically increasing component stands for the effect of amplification in the midlatitude winds due to anthropogenic warming.</p>

Specific features of sandstones of Upper Devonian Tayokuyakhinskaya Formation on southeastern slope of the Kanin Kamen range (Kanin Peninsula)

The results of studying the lithological and geochemical characteristics of sandstones of the Upper Devonian Tayaokuyakhinskaya Formation in the southeastern part of the Kanin Nos Peninsula are presented. The accumulation of sandstones of the Tayaokuyakhinskaya Formation occurred in the absence of volcanic activity in a shallow basin with small periodic fluctuations in sea level, which led to a change in the degree of maturity, sorting, and the ratio of clay and sandy components in the rock. The accumulation of the psammitic strata occurred due to the destruction and redeposition of weakly weathered sedimentary rocks in a moderately warm climate. It was established that the formation of the composition of sandstones was influenced by at least two sources of clastic material — garnet-bearing crystalline shales and feldspar-quartz sandstones metamorphosed into the greenschist facies. The latter, most likely, were the source of the indicative gold contents found in the Devonian clastic rocks.

Perancang Alat Sistem Monitoring Volume Air Pada Tangki Air Berbasis Telegram Dengan Mikrokontroler NodeMCU

At this time the world is experiencing a Covid-19 outbreak which has resulted in all activities being restricted and must implement health protocols to prevent the transmission of the corona virus. One of these health protocols is washing hands regularly. Padang State Polytechnic is an educational institution that applies health protocols by providing water tanks in several places so that everyone who comes to Padang State Polytechnic can wash their hands easily. The water tank available at the Padang State Polytechnic does not have a specific schedule for filling it. This causes the officer in charge to always check the condition of the water tank. At the Padang State Polytechnic, the number of water tanks available is not small. Periodic inspection of the water tank becomes ineffective and causes not all of the water to be fully filled or that there is also a tank that is not filled. Therefore, the Water Volume Monitoring System tool in a Telegram Based Water Tank with a NodeMCU Microcontroller can make it easier for officers to monitor the state of the water via telegram so that the water tank monitoring process at Padang State Polytechnic becomes more effective. The water volume monitoring system tool is built with NodeMCU Microcontroller technology and the Telegram application to check notifications.

How do conservative backbone curves perturb into forced responses? A Melnikov function analysis

Weakly damped mechanical systems under small periodic forcing tend to exhibit periodic response in a close vicinity of certain periodic orbits of their conservative limit. Specifically, amplitude-frequency plots for the conservative limit have often been noted, both numerically and experimentally, to serve as backbone curves for the near resonance peaks of the forced response. In other cases, such a relationship between the unforced and forced response was not observed. Here, we provide a systematic mathematical analysis that predicts which members of conservative periodic orbit families will serve as backbone curves for the forced–damped response. We also obtain mathematical conditions under which approximate numerical and experimental approaches, such as energy balance and force appropriation, are justifiable. Finally, we derive analytic criteria for the birth of isolated response branches (isolas) whose identification is otherwise challenging from numerical continuation.

Acoustic resonance in periodically sheared glass: damping due to plastic events

Using molecular dynamics simulation, we study acoustic resonance in a low-temperature model glass by applying a small periodic shear at a boundary wall.