Showing papers on "Decoupling (electronics) published in 2020"

Is Green Growth Possible

Abstract: The notion of green growth has emerged as a dominant policy response to climate change and ecological breakdown. Green growth theory asserts that continued economic expansion is compatible with our...

A systematic review of the evidence on decoupling of GDP, resource use and GHG emissions, part II: synthesizing the insights

Abstract: Strategies toward ambitious climate targets usually rely on the concept of "decoupling"; that is, they aim at promoting economic growth while reducing the use of natural resources and GHG emissions. GDP growth coinciding with absolute reductions in emissions or resource use is denoted as "absolute decoupling", as opposed to "relative decoupling", where resource use or emissions increase less so than does GDP. Based on the bibliometric mapping in part I (Wiedenhofer et al., this issue), we synthesize the evidence emerging from the selected 835 peer-reviewed articles. We evaluate empirical studies of decoupling related to final/useful energy, exergy, use of material resources, as well as CO2 and total GHG emissions. We find that relative decoupling is frequent for material use as well as GHG and CO2 emissions but not for useful exergy, a quality-based measure of energy use. Primary energy can be decoupled from GDP largely to the extent to which the conversion of primary energy to useful exergy is improved. Examples of absolute long-term decoupling are rare, but recently some industrialized countries have decoupled GDP from both production- and, weaklier, consumption-based CO2 emissions. We analyze policies or strategies in the decoupling literature by classifying them into three groups: (1) Green growth, if sufficient reductions of resource use or emissions were deemed possible without altering the growth trajectory. (2) Degrowth, if reductions of resource use or emissions were given priority over GDP growth. (3) Others, e.g. if the role of energy for GDP growth was analyzed without reference to climate change mitigation. We conclude that large rapid absolute reductions of resource use and GHG emissions cannot be achieved through observed decoupling rates, hence decoupling needs to be complemented by sufficiency-oriented strategies and strict enforcement of absolute reduction targets. More research is needed on interdependencies between wellbeing, resources and emissions.

A Comprehensive Survey on “Various Decoupling Mechanisms With Focus on Metamaterial and Metasurface Principles Applicable to SAR and MIMO Antenna Systems”

Abstract: Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming capability, which can be utilized for controlling radiation pattern for electromagnetic (EM) interference immunity in wireless systems. However, with the growing demand for compact array antennas, the physical footprint of the arrays needs to be smaller and the consequent of this is severe degradation in the performance of the array resulting from strong mutual-coupling and crosstalk effects between adjacent radiating elements. This review presents a detailed systematic and theoretical study of various mutual-coupling suppression (decoupling) techniques with a strong focus on metamaterial (MTM) and metasurface (MTS) approaches. While the performance of systems employing antenna arrays can be enhanced by calibrating out the interferences digitally, however it is more efficient to apply decoupling techniques at the antenna itself. Previously various simple and cost-effective approaches have been demonstrated to effectively suppress unwanted mutual-coupling in arrays. Such techniques include the use of defected ground structure (DGS), parasitic or slot element, dielectric resonator antenna (DRA), complementary split-ring resonators (CSRR), decoupling networks, P.I.N or varactor diodes, electromagnetic bandgap (EBG) structures, etc. In this review, it is shown that the mutual-coupling reduction methods inspired By MTM and MTS concepts can provide a higher level of isolation between neighbouring radiating elements using easily realizable and cost-effective decoupling configurations that have negligible consequence on the array’s characteristics such as bandwidth, gain and radiation efficiency, and physical footprint.

Dual-Band Metasurface-Based Decoupling Method for Two Closely Packed Dual-Band Antennas

Abstract: In this communication, a metasurface-based decoupling method (MDM) is proposed to reduce the mutual couplings at two independent bands of two coupled multiple-input-multiple-output (MIMO) antennas. The metasurface superstrate is composed of pairs of non-uniform cut wires with two different lengths. It is compact in size and effective in decoupling two nearby dual-band patch antennas that are strongly coupled in the H-plane with the edge-to-edge spacing of only 0.008 wavelength at low-frequency band (LB). The antenna is fabricated and measured and the results show that the isolation between two dual-band antennas can be improved to more than 25 dB at both 2.5–2.7 GHz and 3.4–3.6 GHz bands, while their reflection coefficients remain to be below −10 dB after the metasurface superstrate is introduced. Moreover, the total efficiency is improved by about 15% in the low band and the envelope correlation coefficient (ECC) between the two antennas is reduced from 0.46 to 0.08 at 2.6 GHz and 0.08 to 0.01 at 3.5 GHz. The proposed method can find plenty of applications in dual-band MIMO and 5G communication systems.

A Novel Slot-Array Defected Ground Structure for Decoupling Microstrip Antenna Array

Abstract: In this article, a novel slot-array defected ground structure (DGS) for decoupling microstrip antenna array is proposed. The slot-array DGS is etched surrounding each antenna element on the ground plane and parallel to the radiating edges of each antenna element. The decoupling mechanism is elucidated via an equivalent circuit model and the coupled current field analysis, which reveals slot-array DGS has the spatial band-stop characteristic and changes the direction of the partially coupled current, respectively. Both characteristics of the slot-array DGS contribute to mutual coupling reduction. Three practical design examples of applying slot-array DGS to single-linearly polarized (LP), dual-LP, and compact circularly polarized (CP) antenna array are given to illustrate the design process and considerations. The simulated and measured results show that about 50 dB isolation enhancement is obtained by using the slot-array DGS when the edge-to-edge spacing between CP antenna elements is 0.057 wavelength. Additionally, a wheel-shaped absorber based on the electromagnetic loss material is designed and fabricated to reduce the backward radiation caused by slot-array DGS. The absorber has an absorptivity of more than 95% in the frequency range of 1.2–1.35 GHz and suppresses the backward radiation over 12.5 dB in the plane phi = 0° and 16.1 dB in the plane phi = 90° without deteriorating other antenna performances.

Weak-Field-Based Self-Decoupling Patch Antennas

Abstract: In this article, a new self-decoupling method, namely weak-field-based decoupling technique, is proposed and validated based on inset-fed patch antenna arrays. The self-decoupling effect is realized by taking advantage of the inherent weak-field area created by the feeding structure and proposed inset-fed patch. By strategically arranging the array element in the weak-field area of the adjacent antenna element, the coupling strength between adjacent elements can be controlled under a very low level without the need of any additional decoupling circuitry or structures. A two-element patch antenna array was first developed and analyzed, achieving a peak isolation level of 61 dB. Afterward, a four-element linear patch antenna array was designed, fabricated, and measured to further validate the proposed technique. With the distinct advantages of simple structure and effective isolation enhancement, the proposed self-decoupling method is very promising for MIMO applications.

The environmental state and the glass ceiling of transformation

Abstract: What are the capacities of the state to facilitate a comprehensive sustainability transition? It is argued that structural barriers akin to an invisible ‘glass ceiling’ are inhibiting any such tran...

Decomposing the decoupling of CO2 emissions and economic growth in China’s iron and steel industry

Abstract: Building a low-carbon industry is essential for the development of a sustainable economy. To study the relationship between carbon emissions and economic growth of China’s iron and steel (IS) industry, this paper first measures the decoupling relationship between carbon emissions and added value of the IS industry from 2001 to 2016 based on the Tapio decoupling model. The causal-chain decomposition model is then used to decompose the decoupling index into different factors. Results show that carbon emissions and economic growth of the IS industry have mostly weak decoupling. For the influencing factors, decoupling elasticities of emission reduction and value creation exert negative impacts on overall decoupling, and the former one plays a bigger role. Decoupling elasticities of energy electricity and industrial electrification positively improve the total decoupling, but the effect is not stable yet and needs to be further enhanced. Finally, the grey Verhulst model is used to predict the decoupling state by the end of 2025. Forecasting results show that industry will still be in a weak decoupling, but the decoupling state will get better over time. Corresponding policy suggestions are posited based on the empirical findings to facilitate the green and low-carbon development of the IS industry.

A Decoupling and Matching Network Design for Single- and Dual-Band Two-Element Antenna Arrays

Abstract: This article presents a new decoupling and matching network (DMN) design for symmetric, single- and dual-band two-element antenna arrays. The DMNs use parallel-line-based coupling elements. The decoupling between the output ports of the proposed DMN and the reflection coefficients at these ports is obtained using the scattering parameters of the coupled antenna array and those of the DMN. These are clearly expressed as functions of the DMN's design parameters. These design parameters are determined using a simple numerical method to provide high inter-element isolation and good impedance matching for the array. To verify the proposed synthesis procedure, three DMN example designs are considered. These include one for a single-band array and two for dual-band arrays having different frequency ratios. Prototypes of these antennas along with their DMNs were designed, fabricated, and experimentally characterized. In each case, a good agreement between the measured and theoretical results is achieved. Simulation and measurement results show that the proposed DMN design and its associated synthesis procedure can be employed to significantly improve the interelement isolation of single- and dual-band, two-element arrays in various scenarios.

Identifying Surface Reaction Intermediates in Plasma Catalytic Ammonia Synthesis

Abstract: Ammonia synthesis by plasma catalysis has emerged as an alternative process for decoupling nitrogen fixation from fossil fuels. Plasma activation can potentially circumvent the limitations of conve...

Decoupling and Teaming up: The Rise and Proliferation of Transnational Municipal Networks in the Field of Migration:

Abstract: Cities claim an ever-larger role in migration governance, often by means of progressive policies that “decouple” the local from the national. The literature on this “local turn” has generally faile...

Optimization Design and Control of Single-Stage Single-Phase PV Inverters for MPPT Improvement

Abstract: Due to the inherent double-frequency (2 f 0) ripple in single-stage single-phase photovoltaic grid-connected inverters, the maximum power point tracking (MPPT) will inevitably be affected. To improve the MPPT performances, a passive LC power decoupling circuit with a robust second-order sliding-mode control (SOSMC) is thus proposed in this article. With the passive LC decoupling path, the double-frequency pulsation on the dc link is effectively cancelled out. Thus, the MPPT accuracy is significantly enhanced, and the utilization of a small dc-link capacitor becomes possible. However, resonance between the LC circuit and the main dc-link capacitor may appear, which can be damped through an active damping method. Additionally, the proposed SOSMC ensures good steady-state, dynamic performance (voltage fluctuation and settling time), and the robustness of the dc-link voltage, which is also beneficial to MPPT control in terms of high accuracy and fast dynamics. The systematic design of SOSMC is presented, and a detailed parameter optimization design of LC decoupling circuit is discussed. Experimental tests are performed on a 2.5-kW single-stage single-phase grid-connected inverter, and the results validate the effectiveness of the proposed strategy.

A General and Systematic Method to Design Neutralization Lines for Isolation Enhancement in MIMO Antenna Arrays

Abstract: A general and systematic approach is the first time proposed in this paper to design the neutralization line (NL) for isolation enhancement in multiple-input multiple-output (MIMO) antenna arrays. Each NL consists of a metal strip and a reactive component attached at its middle position. It is connected with every two antenna radiators to generate an additional coupling path against the original antenna coupling for isolation enhancement. A general network model that leads to a systematic design procedure is developed to meet the required isolation criteria. Three practical examples are presented and used to verify the proposed NL-based decoupling technique (DT). The measurement results align well with simulations. For all these examples, good impedance matching, isolation over 25 dB, total radiation efficiencies over 70%, and very low envelop correlation coefficients (ECCs) can be achieved simultaneously after adopting the proposed NL DT. Compared with previous decoupling works using parasitic elements, decoupling networks or NLs, the proposed method can achieve either a much wider decoupling bandwidth or a much smaller antenna separation distance while keeping a low design complexity along with systematic design procedure.

A Novel Wideband Decoupling Network for Two Antennas Based on the Wilkinson Power Divider

Abstract: In this article, a wideband decoupling network (DN) is presented based on the Wilkinson power divider (WPD). The DN is composed of 2 two-way unequal WPDs, three transmission lines (TLs), and two reactive components. Two techniques are introduced for the wideband performance: 1) by using the WPD with high output isolation, the antenna matching becomes independent of antenna decoupling. So, the decoupled antennas with the proposed DN could perform broad impedance bandwidths without using matching networks and 2) the DN is designed to minimize antennas’ coupling coefficients at two frequencies, which collectively contribute to a broader decoupling bandwidth. In addition, rigorous design formulas are presented along with systematic design procedures. Based on this, the TL lengths and component reactances can be precisely calculated instead of being fitted to achieve high antenna isolation. Two decoupling cases using the proposed DN and its simplified model are presented and compared to give an intuitive illustration of the wideband mechanism. The measurement results for decoupling case #1 show that a very wide isolation bandwidth of 23.7%, total efficiency over 65%, and the envelope correlation coefficients (ECCs) less than 0.05 can be achieved simultaneously using the proposed DN.

Adaptive robust decoupling control of multi-arm space robots using time-delay estimation technique

Abstract: The most distinctive difference between a space robot and a base-fixed robot is its free-flying/floating base, which results in the dynamic coupling effect. The mounted manipulator motion will disturb the position and attitude of the base, thereby deteriorating the operational accuracy of the end effector. This paper focuses on decoupling or counteracting the coupling between the manipulator and the base. The dynamics model of multi-arm space robots is established using the composite rigid dynamics modeling approach to analyze the dynamic coupling force/torque. An adaptive robust controller that is based on time-delay estimation (TDE) and sliding mode control (SMC) is designed to decouple the multi-arm space robot. In contrast to the online computation method, the proposed controller compensates for the dynamic coupling via the TDE technique and the SMC can complement and reinforce the robustness of the TDE. The global asymptotic stability of the proposed decoupling controller is mathematically proven. Several contrastive simulation studies on a dual-arm space robot system are conducted to evaluate the performance of the TDE-based SMC controller. The results of qualitative and quantitative analysis illustrate that the proposed controller is simpler and yet more effective.

Finite-Time Feedforward Decoupling and Precise Decentralized Control for DC Microgrids Towards Large-Signal Stability

Abstract: This paper is initiated by considering an emerging practical issue that dc microgrids should be able to operate with a large-signal stability sense when feeding both resistive loads and constant power loads (CPLs). To be more specific, the stability should be ensured in the presence of large variations of integrated renewable sources and CPLs, system internal uncertainties, external disturbances, coupled interactions, and other adverse effects. From a control point of view, we intentionally propose a general solution to realize the exact decentralized tracking control task for interconnected systems. First, an alternative finite-time feedforward decoupling mechanism is presented, which is essentially different from existing design approaches via feedback domination or recursive cancellation processes. Second, a composite controller can be straightforwardly built from the system information since it is detached from stability analysis. One major advantage of the proposed design framework is that it reduces the design complexity and therefore facilitates the practical implementations. As a direct application, a simple decentralized composite controller is constructed for an autonomous dc microgrid system. Both numerical simulation and experimental comparison results show that a large-signal stability is achieved for dc microgrids under a range of different situations.

Phase Compensation for Decoupling of Large-Scale Staggered Dual-Polarized Dipole Array Antennas

Abstract: Staggered array antenna is a common array configuration for large-scale array antennas due to its favorable radiation characteristics and relatively large element spacing. In developing a compact staggered dipole array, the most challenging issue is how to simultaneously reduce the four mutual couplings taking place between adjacent co-polarized antenna elements with diversified phase laggings. A large difference in the phase of different mutual couplings makes simultaneous reduction of all the mutual couplings by applying the recently developed array-antenna decoupling surface (ADS) technique difficult. In this article, a phase compensation method by using a staple-shaped probe for alleviating the largest phase offset is proposed conceptually and verified experimentally. With the proposed phase compensation method, the ADS technique can be effectively applied to a compact staggered dipole array with a wideband simultaneous decoupling. The design guideline for the phase compensation probe is presented by EM simulation and a parametric study. Two practical design examples of dual polarized staggered dipole arrays are given to demonstrate the effectiveness of the proposed phase compensation method in conjunction with ADS, showing a promising potential for wideband simultaneous decoupling of a large-scale dual polarized staggered dipole array-antenna.

Mutual Coupling Reduction in a Multi-band MIMO Antenna Using Meta-Inspired Decoupling Network

Abstract: This article presents a unique meta-inspired decoupling method to reduce the isolation in a multi-band MIMO antenna. The proposed textile-based antenna is designed to cover the frequency spectra of IEEE 802.11a and b/g/n (2.4–2.484 GHz and 5.15–5.85 GHz) WLAN applications. The isolation improvement in multiple WLAN frequencies are achieved by a modified SRR meta-inspired structure without upsetting the parameters of the MIMO antenna. The maximum isolation improvement of around 10 dB is obtained at 2.4 GHz (S21 9 respectively over the desired bands. The measured results show a good agreement with the simulated one.

A Configurable Virtual Impedance Method for Grid-Connected Virtual Synchronous Generator to Improve the Quality of Output Current

Abstract: There are two significant problems for the virtual synchronous generator (VSG) under the nonideal grid, including power coupling and current distortion. Although the virtual impedance (VI) is often used to decouple the control of active power and reactive power, it can neither suppress current harmonics nor solve current imbalance caused by the nonideal grid. Therefore, this paper proposes the configurable virtual impedance (CVI) approach to improve both the power coupling and the output current quality. The proposed methodology could aid the independent design of the virtual sequence impedance (VSI) for any harmonics, of which the virtual fundamental positive sequence impedance can be used to realize power decoupling, and the other VSI is designed to mitigate current aberration. Due to the requirements of VSI, the novel harmonic extraction algorithm (NHEA) based on the state space model is presented to separate the positive-sequence component (PSC), negative-sequence component (NSC), and zero-sequence component (ZSC) in the fundamental and harmonic current. Then, under this harmonic extractor, 90° phase lead for each SC can be easily achieved by means of simple vector rotation. Excellent extraction performance of the NHEA and remarkable ability of current quality control and power decoupling regarding CVI are demonstrated by simulations and experiments.

Control Strategies and Power Decoupling Topologies to Mitigate 2ω-Ripple in Single-Phase Inverters: A Review and Open Challenges

Abstract: This paper provides a comprehensive review of the control approaches and the power-decoupling topologies to mitigate 2ω-ripple problem in the single-phase inverters, its solutions, and discusses open challenges yet to be addressed. The cause and effects of 2ω-ripple problem and its solution based on the passive and active power-decoupling techniques are discussed. A subcategory of the active power-decoupling technique nominated as the control-oriented compensation technique is reviewed in detail, this technique can achieve the ripple-mitigation at the source through the control but not necessarily adds extra circuit or active filter to the system. The control-oriented compensation techniques can be applied in the two-stage DC-DC-AC converters and the single-stage inverters having a front-end control capability with the H-bridge such as in the quasi-switched-boost inverters. The merits and associated challenges of these techniques are listed and summarized in a tabular form. Finally, a conclusive discussion with open challenges is presented.