Asymmetric Transmission Mechanism Research Articles

Differential impacts of COVID-19 on Indian sectors: Resilience of pharmaceuticals and automobiles, contrasting with negative effects on IT and real estate - An ARIMA-GARCH analysis

The COVID-19 pandemic had a profound impact on financial markets worldwide, including those in India, and it has resulted in increased volatility with spillover effects across various industries. This study provides insights into the differential impact of COVID-19 on various industries in India by employing the ARIMA-GARCH model. The study utilized daily data spanning from 2017 to 2023 to examine industry responses during the COVID-19 pandemic, delineating three distinct periods: 2017 to 2021, denoting the pre pandemic era; 2020 to 2023, encompassing the turbulent during-COVID phase; and 2021 to 2023, representing the post-COVID era. In this study, the IT and real estate sectors are considered dependent variables, while the automotive and pharmaceutical sectors are regarded as independent variables. The primary aim is to uncover the complex influence of the IT industry on the automotive, pharmaceutical, and real estate sectors during these time frames; and to elucidate how the real estate industry reciprocally affects these sectors. Our empirical analysis provides insights into the asymmetric transmission mechanism of spillovers. By disentangling overall shocks into macroeconomic impacts affecting all sectors and industrial influences exclusive to specific sectors, we discern that macroeconomic shocks, rather than industrial shocks, primarily dictate the asymmetry in spillover transmission dynamics. This study contributes to a comprehensive understanding of how industries responded to the unprecedented challenges posed by the pandemic, offering valuable insights for strategic decision-making and policy formulation in the post-COVID-19 era.

Non‐Interleaved Bilayer Complex‐Amplitude Janus Metasurface Enabling Energy‐Tailorable Bidirectional Wave Modulation

AbstractJanus metasurfaces have attracted significant attention due to their key feature of asymmetric transmission in numerous practical applications, such as asymmetric data inscription in communications and dual side displays in smart mobile devices. More compact and integrated spatial wave modulation components call for implementations of non‐interleaved bilayer complex‐amplitude (CA) Janus metasurfaces. Here, by introducing composite geometry phase into propagation phase, direction‐dependent decoupling relation between amplitude and phase engineering is derived, and the mechanism of energy‐tailorable bidirectional wave modulation is elucidated via extremely simple single‐pixeled Janus elements. A non‐interleaved bilayer CA Janus metasurface is thus proposed. Bidirectional amplitude‐phase profiles with both‐transmission (T–T) or transmission–reflection‐integration (T–R) operational modes can readily be achieved. Numerical analysis and experimental verification of direction‐dependent energy allocation and reciprocal asymmetric holograms are performed to demonstrate the excellent manipulation accuracy and decorrelation under bidirectional illuminations. On this basis, a series of coplanar image syntheses, including frequency–polarization multitasking and T–R dual‐channel multiplexing, based on the proposed bidirectional CA modulation mechanism are experimentally demonstrated in the microwave region. This asymmetric transmission mechanism will promote developments of Janus metasurfaces for multichannel processing and information multiplexing applications in miniaturized and highly integrated systems.

Geographical Indications and Price Volatility Dynamics of Lamb Prices in Spain

For decades, food quality standards have attracted the interest of governance institutions and regulation authorities, who have responded to the increasing and demanding societal challenges. In addition, the open debate on significant variability and unusually high levels of agrifood prices recorded in 2007 and later in 2011 affect the behavior of the chain actors involved. As an attempt to bring together these wide concerns within a quantitative framework, a comparative analysis of the performance of the price volatility dynamics allowing for asymmetric behavior along the supply chain of a protected geographical indication (PGI)-certified lamb and its corresponding non-PGI counterpart, both located in the same region of Spain, was undertaken using weekly farm-retail prices for the period 2011–2018. The results indicate the existence of significant volatilities and an asymmetric transmission mechanism along the non-PGI-certified lamb supply chain, whereas the PGI-certified supply chain is impacted by volatility effects, yet characterized by symmetric behavior, which may suggest a high degree of relative market efficiency.

Analysis and design of new chiral metamaterials with asymmetric transmission characteristics

Asymmetric transmission (AT) metamaterials are extensively studied and applied in the fields of polarization converters and photodiodes. In order to further improve the properties of polarization conversion and unidirectional conduction in the high frequency band and to implement their tunability, the novel chiral electromagnetic metamaterials are studied. By the topology optimization technique, a new type of double-layer L-shaped variant metamaterial structure with excellent asymmetric transmission characteristics is designed. The objective function is to maximize the asymmetric transmission coefficient for the linear polarization wave. The rotationally symmetrical design domain is determined by considering polarization conversion and computation efficiency simultaneously. The design domain of upper layer is divided into two parts which are both the 180° rotationally symmetrical. The design domain of the upper layer and lower layer are the 90° rotationally symmetrical around the <i>x</i> and <i>z</i> axis respectively. Therefore, the number of design variables is only 18. Asymmetric transmission of linear polarization wave in the K band and Ka band are implemented. Numerical simulation results and experimental results show that the optimized chiral metamaterial has excellent asymmetric transmission characteristics, and its asymmetric transmission coefficient reaches 0.8562 at a frequency of 21.65 GHz and 0.8175 at a frequency of 28.575 GHz. Its asymmetric transmission mechanism is expounded by analyzing the electric field and surface current distribution at the resonance frequency. Based on the optimized chiral metamatertials, the reasonable geometric parameters are selected and the rotation angle of the metal layer is changed in order to further achieve the tunable AT characteristics. First, the influences of the dielectric substrate layer, the thickness of the metal layer and the side length of the grid on resonance frequency and asymmetric transmission coefficient are analyzed respectively, which provides the basis for the reasonable adjustment of the structural parameters to obtain better asymmetric transmission characteristics. After the reasonable geometric parameters are determined, the rotational angle of the upper metal layer and lower metal layer are changed. The linearly and circularly polarized wave are simultaneously achieved in the K band. In this article, the topology optimization technique is used to design the asymmetric transmission chiral metamaterial structure. The design process has a clear direction. The optimized asymmetric transmission chiral metamaterial has the simple structure type and the easy tunability of its asymmetric transmission characteristics. It can be used widely and easily in the fields of polarization converters and photodiodes. This design method has a broad application prospect in the chiral metamaterial field.

Asymmetric price transmission effect of corn on hog: evidence from China

In this study, we used monthly corn price and hog price data from January 2000 to June 2015 to conduct an empirical analysis based on a smooth transition regression (STR) model. The analysis confirms and explains the asymmetric transmission mechanism and process of the smooth transformation of corn prices to hog prices and measures the mechanism conversion threshold. Using the smooth transformation mechanism and its threshold as its foundations, this study breaks up continuous smooth transfer price volatility transmission effects into completely linear, not completely linear, and nonlinear mechanism states. Based on these states, the influence of corn price on hog price fluctuation is attributed to cost-push inflation, risk stabilisation effects, and the coexistence of cost-push and risk-stabilisation effects from the perspective of adaptive expectations.

An implemented method of asymmetric transmission for arbitrary polarization base in multi-layered chiral meta-surface

Asymmetric transmission of linearly or circularly polarized waves is a well-established property not only for three-layered chiral structures but for multi-layered ones. Here we show a method which can simultaneously implement asymmetric transmission for arbitrary base vector polarized wave in multi-layered chiral meta-surface. We systematically study the implemented method based on a multi-layered chiral structure consisting of a y-shape, a half gammadion and an S-shape in the terahertz gap. A numerical simulation was carried out, followed by an explanation of the asymmetric transmission mechanism in these structures proposed in this work. The simulated results indicate that the multi-layered chiral structure can realize a maximum asymmetric transmission of 0.89 and 0.28 for circularly and linearly polarized waves, respectively, which exhibit magnitude improvement over previous chiral metamaterials. Specifically, the maximum asymmetric transmitted coefficient of the multi-layered chiral structure is insensitivity to the incident angles from 0° to 45° for circularly polarized components. Additionally, we also study the influence of structural parameters on the asymmetric transmission effect for both linearly and circularly polarized waves in detail.

The Interest Rate Unbound?

What have we learned from the recent international experiences with negative interest rates? This paper reviews the evidence. Negative interest rates have proved so unpopular that it is unlikely that a full liberation from the Zero Lower Bound is within sight. The Swiss experience, however, suggests it might be possible to adopt significantly lower interest rates by capitalizing on the unwillingness of banks to transmit negative rates to retail depositors while making it financially feasible for them to do so. The resulting asymmetric transmission mechanism may suit small open economies in need of a negative interest differential.

Unidirectional wave transmission in a diatomic acoustic metamaterial

In this study, we propose the use of dual resonators to design a linear diatomic metamaterial, consisting of several small-sized unit cells, to realize large unidirectional wave transmission in low frequency domain (below 1 kHz). The asymmetric transmission mechanism is theoretically derived and systematically investigated. Numerical results are verified using both lattice structures and continuum models. This passive system does not require external energy supply or result in any frequency conversion. Various wave transmission band gaps, including passing band, stopping band gap, and asymmetric transmission band, can be theoretically predicted and mathematically controlled, which extends the design concept of unidirectional transmission devices. The asymmetric transmission band can be easily altered by careful and deliberate design of the unit size geometrical parameters and material properties. This proposed idea offers a new design concept in wave energy control through unidirectional systems, and may be applied to practical applications such as ultrasound imaging, directional transducer, and noise control.

Asymmetric wave transmission in a diatomic acoustic/elastic metamaterial

Asymmetric acoustic/elastic wave transmission has recently been realized using nonlinearity, wave diffraction, or bias effects, but always at the cost of frequency distortion, direction shift, large volumes, or external energy. Based on the self-coupling of dual resonators, we propose a linear diatomic metamaterial, consisting of several small-sized unit cells, to realize large asymmetric wave transmission in low frequency domain (below 1 kHz). The asymmetric transmission mechanism is theoretically investigated, and numerically verified by both mass-spring and continuum models. This passive system does not require any frequency conversion or external energy, and the asymmetric transmission band can be theoretically predicted and mathematically controlled, which extends the design concept of unidirectional transmission devices.

Mode Converter Optical Isolator Based on Dual Negative Refraction Photonic Crystal

A new design of an optical isolator based on photonic transitions in the interbands of a honeycomb structure that generates a dual negative refraction in a photonic crystal is presented. The involved photonic transition is associated to the perturbation of the dielectric constant of the medium. The band structure is determined using the plane wave method where the transmission spectra, field profile, and mode amplitudes are obtained by applying the finite difference time domain method. Due to the time-dependent perturbation of the refractive index of the medium that constitutes the dual negative refraction, asymmetric transmission mechanism is achieved for one of the desired modes, demonstrating optical isolation. Using the dual negative refraction effect in photonic crystal structure, the optical isolation is reported for only one of the desired optical modes. It is anticipated that the proposed mode conversion mechanism can be employed for designing ultrahigh-speed optical interconnections. The proposed optical isolator model is expected to have a significant impact on designing ultrahigh-speed integrated optical platforms.