Fault Tolerance in Programmable Metasurfaces: The Beam Steering Case

Metasurfaces, the two-dimensional counterpart of metamaterials, have caught great attention thanks to their powerful control over electromagnetic waves. Recent times have seen the emergence of a variety of metasurfaces exhibiting not only countless functionalities, but also a reconfigurable or even programmable response. Reconfigurability, however, entails the integration of tuning and control circuits within the metasurface structure and, as this new paradigm moves forward, new reliability challenges may arise. This paper examines, for the first time, the reliability problem in programmable metamaterials by proposing an error model and a general methodology for error analysis. To derive the error model, the causes and potential impact of faults are identified and discussed qualitatively. The methodology is presented and instantiated for beam steering, which constitutes a relevant example for programmable metasurfaces. Results show that performance degradation depends on the type of error and its spatial distribution and that, in beam steering, error rates over 10% can still be considered acceptable

Error analysis of programmable metasurfaces for beam steering

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Recent years have seen the emergence of programmable metasurfaces, where the user can modify the electromagnetic (EM) response of the device via software. Adding reconfigurability to the already powerful EM capabilities of metasurfaces opens the door to novel cyber-physical systems with exciting applications in domains such as holography, cloaking, or wireless communications. This paradigm shift, however, comes with a non-trivial increase of the complexity of the metasurfaces that will pose new reliability challenges stemming from the need to integrate tuning, control, and communication resources to implement the programmability. While metasurfaces will become prone to failures, little is known about their tolerance to errors. To bridge this gap, this paper examines the reliability problem in programmable metamaterials by proposing an error model and a general methodology for error analysis. To derive the error model, the causes and potential impact of faults are identified and discussed qualitatively. The methodology is presented and exemplified for beam steering, which constitutes a relevant case for programmable metasurfaces. Results show that performance degradation depends on the type of error and its spatial distribution and that, in beam steering, error rates over 20% can still be considered acceptable.This work has been supported by the European Commission under grant H2020-FETOPEN-736876 (VISORSURF) and by ICREA under the ICREA Academia programme. The person and base station icons in Figure 1 were created by Jens Tärningand Clea Doltz from the Noun Project.Peer ReviewedPostprint (author's final draft

Economic growth and environmental pollution in Iran: evidence from manufacturing and services sectors

This article aims to answer the question of whether the manufacturing (and mining) and services sectors in Iran should be reconstructed or grown as before, in order to improve the environmental quality. The global warming, if not global burning, is a dire warning about environmental pollution dangers to everyone, living on the Earth. In this field, Iran is a good candidate due to its significantly high share of CO2 emissions in proportion to the low share of economic growth in the world which can be remedied by economic growth, based on Environmental Kuznets Hypothesis (EKH). We employ the Auto-Regressive Distributed Model (ARDL) to examine the long run equilibrium relationship between CO2 emission and economic growth. The results show that, regarding EKC, the nexus of CO2 emissions and economic growth in either sector is in a sharply ascending phase. It implies that if manufacturing (and mining) and services sectors inflate, the quality of environment will decline owing to the intensive and pollutant energy-using structures. Thus, rather than growing, they should be reconstructed by importing cleaner and more efficient technologies and developing internal inventions

A current and future study on non-isolated DC`DCconverters for photovoltaic applications.

Photovoltaic (PV) is a fast growing segment among renewable energy (RE) systems, whose development is owed to depleting fossil fuel and climate-changing environmental pollution. PV power output capacity, however, is still low and the associated costs still high, so efforts continue to develop PV converter and its controller, aiming for higher power-extracting efficiency and cost effectiveness. Different algorithms have been proposed for Maximum Power Point Tracking (MPPT). Since the choice of right converter for different application has an important influence in the optimum performance of the photovoltaic system, this paper reviews the state-of-the-art in research works on non-isolated DC–DC buck, boost, buck–boost, Cúk and SEPIC converters and their characteristics, to find a solution best suiting an application with Maximum Power Point Tracking. Review shows that there is a limitation in the system's performance according to the type of converter used. In can be concluded that the best selection of DC–DC converter which is really suitable and applicable in the PV system is the buck–boost DC–DC converter since it is capable of achieving optimal operation regardless of the load value with negotiable performance efficiency and price issue

Novel Highly Porous Ceramic and Metal Aerogels from Xerogel Powder Precursors, and Methods for their Production and Use

The present invention discloses novel methods for producing highly porous ceramic and/or metal aerogel monolithic objects that are hard, sturdy, and resistant to high temperatures. These methods comprise preparing nanoparticulate oxides of metals and/or metalloids via a step of vigorous stirring to prevent gelation, preparing polymer-modified xerogel powder compositions by reacting said nanoparticulate oxides with one or more polyfunctional monomers, compressing said polymer-modified xerogel powder compositions into shaped compacts, and carbothermal conversion of the shaped xerogel compacts via pyrolysis to provide the highly porous ceramic and/or metal aerogel monolithic objects that have the same shapes as to their corresponding xerogel compact precursors. Representative of the highly porous ceramic and/or metal aerogel monolithic objects of the invention are ceramic and/or metal aerogels of Si, Zr, Hf, Ti, Cr, Fe, Co, Ni, Cu, Ru, Au, and the like. Examples include sturdy, shaped, highly porous silicon carbide (SiC), silicon nitride (Si3 N4), zirconium carbide (ZrC), hafnium carbide (HfC), chromium carbide (Cr3 C2 ), titanium carbide (TiC), zirconium boride (ZrB2 ), hafnium boride (HfB2 ), and metallic aerogels of iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), ruthenium (Ru), gold (Au), and the like. Said aerogel monolithic objects have utility in various applications such as, illustratively, in abrasives, in cutting tools, as catalyst support materials such as in reformers and converters, as filters such as for molten metals and hot gasses, in bio-medical tissue engineering such as bone replacement materials, in applications requiring strong lightweight materials such as in automotive and aircraft structural components, in ultra-high temperature ceramics, and the like

Environment, Energy, and Environmental Productivity of Energy: A Decomposition Analysis in China and the US

The global warming, if not global burning, is a dire warning about environmental pollution dangers to everyone, living on the only one Earth. This study aims to measure relative contributors to the environmental quality changes during 2002-2011 using Logarithmic Mean Divisia Index in China and the US. Since these countries are the biggest polluters in the world, the decomposition technique is used to cut their wide environmental issues into the tiny bits of problems, being easy to cope with. Moreover, we employed Environmental Performance Index (EPI) to evolve the concept of Environmental Productivity of Energy (EPE). The results suggest that economic growth and income equality are environmentallyfriendly while energy consumption is environmentally-unfriendly; and the Environmental Productivity of Energy (EPE) and technology progress are environmentally-moody (with various effects on environment). Consequently, the policy makers are advised to develop those economic sectors which are independent of pollutant energies; to replace the black energies by the green ones; and to invest on the research about the products whose demand is price inelastic

Price and Income Elasticities of Gasoline Demand in Iran: Using Static, ECM, and Dynamic Models in Short, Intermediate, and Long Run

Price and income elasticities of gasoline demand show whether the price policy, pursued by the Iranian government, can decrease the high gasoline consumption sufficiently or not. Since the two oil price shocks in 1970 and 1973, interest in the study of oil products demand has increased considerably, especially on gasoline. High gasoline consumption is a serious crisis in Iran, posing economically, politically, and environmentally threats. In this study, the elasticities are estimated over three intervals, short run, intermediate run, and long run in Iran during 1976-2010, by putting the estimates of Error Correction Model (ECM), static model, and dynamic model in an increasing order, respectively. The short run, intermediate run, and long run price elasticities are −0.1538, −0.1618, and −0.3612 and the corresponding income elasticities are 0.2273 - 0.3581, 0.4636, and 0.7284, respectively. Not only do these elasticities imply that the gasoline demand is price and income inelastic but also the adjustment velocity, estimated by ECM, is a low point at −0.1942. Based on the estimations, the gasoline demand responds to the changes of price and income slightly and slowly. Therefore, policy makers should develop more strategies to reduce gasoline consumption, for example, substitute goods, public transportation systems, and environmental standards setting

Economic growth and environmental pollution in Iran: evidence from manufacturing and services sectors

This article aims to answer the question of whether the manufacturing (and mining) and services sectors in Iran should be reconstructed or grown as before, in order to improve the environmental quality. The global warming, if not global burning, is a dire warning about environmental pollution dangers to everyone, living on the Earth. In this field, Iran is a good candidate due to its significantly high share of CO2 emissions in proportion to the low share of economic growth in the world which can be remedied by economic growth, based on Environmental Kuznets Hypothesis (EKH). We employ the Auto-Regressive Distributed Model (ARDL) to examine the long run equilibrium relationship between CO2 emission and economic growth. The results show that, regarding EKC, the nexus of CO2 emissions and economic growth in either sector is in a sharply ascending phase. It implies that if manufacturing (and mining) and services sectors inflate, the quality of environment will decline owing to the intensive and pollutant energy-using structures. Thus, rather than growing, they should be reconstructed by importing cleaner and more efficient technologies and developing internal inventions

Price and Income Elasticities of Gasoline Demand in Iran: Using Static, ECM, and Dynamic Models in Short, Intermediate, and Long Run

Price and income elasticities of gasoline demand show whether the price policy, pursued by the Iranian government, can decrease the high gasoline consumption sufficiently or not. Since the two oil price shocks in 1970 and 1973, interest in the study of oil products demand has increased considerably, especially on gasoline. High gasoline consumption is a serious crisis in Iran, posing economically, politically, and environmentally threats. In this study, the elasticities are estimated over three intervals, short run, intermediate run, and long run in Iran during 1976-2010, by putting the estimates of Error Correction Model (ECM), static model, and dynamic model in an increasing order, respectively. The short run, intermediate run, and long run price elasticities are −0.1538, −0.1618, and −0.3612 and the corresponding income elasticities are 0.2273 - 0.3581, 0.4636, and 0.7284, respectively. Not only do these elasticities imply that the gasoline demand is price and income inelastic but also the adjustment velocity, estimated by ECM, is a low point at −0.1942. Based on the estimations, the gasoline demand responds to the changes of price and income slightly and slowly. Therefore, policy makers should develop more strategies to reduce gasoline consumption, for example, substitute goods, public transportation systems, and environmental standards setting