Coupling Loop Research Articles

An improved derivative‐based phase‐locked loop for single‐phase grid synchronization under abnormal grid conditions

SummaryGenerating a quadrature signal in a single‐phase system using a second‐order generalized integrator (SOGI) requires accurate frequency information. The standard SOGI phase‐locked loop (PLL) includes frequency feedback to the SOGI. However, during grid abnormalities such as voltage sag/swell and phase angle jumps, the SOGI‐PLL faces frequency disturbances that propagate to the phase detector (PD) and affects the quadrature signal generator (QSG). Furthermore, the SOGI‐PLL having two loops dependent on each other creates loop coupling phenomena; either a change in phase or frequency affects each other. SOGI‐PLL is tuning sensitive, as the SOGI block has a gain that needs to be adjusted, increases the complexity, and affects the performance of the system. There is a trade‐off between SOGI gain and PLL parameters that needs to be considered for adequate parameter design to provide accurate grid synchronization while maintaining the stability of the system. To attain better performance, researchers have proposed derivative‐based PLL (DPLL). The conventional DPLL faces challenges to noise and harmonics amplification. This paper presents an improved DPLL for single‐phase grid synchronization under adverse grid conditions. The improved derivative‐based PLL (IDPLL) comprises two improved derivative‐based quadrature signal generator (IDQSG) blocks to extract the phase‐error information for accurately estimating phase and frequency. The detailed mathematical modeling and bode plot for the IDQSG and IDPLL are presented. The proposed IDQSG eliminates the requirement of gain tuning, hence reducing complexity. Moreover, there is no interdependent loop in the IDPLL, which significantly improves the dynamic performance. A hardware setup is developed to evaluate the performance of the system in real‐time. The experimental results are obtained using an field programmable gate array (FPGA)‐based controller.

Dual-Loop μ-Synthesis Direct Thrust Control for Turbofan Engines

As the power unit of an aircraft, the engine’s primary task is to provide the demanded thrust, making research on direct thrust control crucial. However, being a complicated multivariable system, effective multivariable direct thrust control methods are currently lacking. The main content of this paper is threefold. First, it presents a dual-loop multivariable μ-synthesis direct thrust control scheme for mixed-exhaust low-bypass turbofan engines, which is a typical rotationally symmetric machine. The scheme adjusts fuel flow for thrust control and nozzle area to control the turbine pressure ratio, ensuring thrust tracking while maintaining the engine’s key parameters within safe limits. Second, a fast, accurate thrust estimation algorithm based on aerodynamic thermodynamics and component characteristics is introduced. At last, considering the model uncertainties between off-design and design points, a weight function frequency shaping μ-synthesis control design method is proposed to address internal loop coupling and external disturbance suppression. Nonlinear simulations within the flight envelope show that μ-synthesis direct thrust control achieves robust servo tracking and disturbance rejection, with a maximum steady-state thrust error of no more than 0.1%, and the key parameters are not over their safety boundaries.

Textronic Capacitive Sensor with an RFID Interface.

This article presents an innovative combination of textile electrical circuits with advanced capabilities of electronic RFID sensors, indicating the revolutionary nature of the development of textronics, which is used in various areas of life, from fashion to medicine. A review of the literature relating to the construction of textronic RFID identifiers and capacitive textronic sensors is performed. Various approaches to measuring capacity using RFID tags are discussed. This article focuses on presenting the concept of a capacitive sensor with an RFID interface, consisting of a microelectronic part and a textile part. The textile part is based on the WL4007 material, where antennas and capacitive sensors are embroidered using SPARKFUN DEV 11791 conductive thread. The antenna is a half-wave dipole designed to operate at a frequency of 860 MHZ. The microelectronic part is sewn to the textile part and consists of a microcontroller, an RFID-integrated circuit and a coupling loop, placed on the PCB. The embroidered antenna is coupled with a loop on the microelectronic module. This article focuses on presenting various designs of textronic electrodes, enabling various types of measurements. Article presents capacitance measurements of individual sensor electrodes, made using a measuring bridge and a built RFID tag. The sensors' capacity measurement results are shown.

A Method to Reduce PDN Impedance Based on Multicapacitor Loop Coupling

A Method to Reduce PDN Impedance Based on Multicapacitor Loop Coupling

Fourier series-based modelling of the effects of thermal coupling on the transient dynamics of component loops in a coupled natural circulation loop

Energy efficiency in process industry and passive safety systems in nuclear power plants necessitate the use of buoyancy driven heat exchangers. The current study presents a 1-D numerical model of the buoyancy driven fluid system in a Coupled Natural Circulation Loop (CNCL) comprising water as the working fluid. In this study water at different temperatures is considered as the operating fluid in each of the loops. The study employs a 1-D model derived using a semi-analytical Fourier series. A validation study was carried out using the relevant literature to verify the mathematical model. A detailed parametric study on individual NCLs and their coupled system was conducted by varying the cross-sectional area keeping the other parameters constant to gain insights into the effect of thermal coupling on the long-term transient dynamics of each of the individual loops of the CNCL system, for stable, unstable – periodic, and unstable – chaotic conditions. The dynamics were analysed using the difference between transient buoyancy and viscous forces, and it was found that the overall heat transfer coefficient influences the coupling behaviour and the dynamics of the component loops in a CNCL. At lower values of the overall heat transfer coefficient, the component loops in the CNCL nearly retain their independent behaviour, i.e., the component loops hardly influence each other. It was also found that the temperature dependent fluid properties influence the stability of the CNCL system in some cases.

Faa1 membrane binding drives positive feedback in autophagosome biogenesis via fatty acid activation.

Autophagy serves as a stress response pathway by mediating the degradation of cellular material within lysosomes. In autophagy, this material is encapsulated in double-membrane vesicles termed autophagosomes, which form from precursors referred to as phagophores. Phagophores grow by lipid influx from the endoplasmic reticulum into Atg9-positive compartments and local lipid synthesis provides lipids for their expansion. How phagophore nucleation and expansion are coordinated with lipid synthesis is unclear. Here, we show that Faa1, an enzyme activating fatty acids, is recruited to Atg9 vesicles by directly binding to negatively charged membranes with a preference for phosphoinositides such as PI3P and PI4P. We define the membrane-binding surface of Faa1 and show that its direct interaction with the membrane is required for its recruitment to phagophores. Furthermore, the physiological localization of Faa1 is key for its efficient catalysis and promotes phagophore expansion. Our results suggest a positive feedback loop coupling phagophore nucleation and expansion to lipid synthesis.

An Adaptive Reclosing Scheme for Cross-Line Faults on Double-Circuit Wind Power Outgoing Lines with Shunt Reactors

Wind turbines are vulnerable to negative sequence current injection, the conventional automatic reclosing scheme for wind power outgoing lines, since we may inject negative sequence components into the system and reclose it without distinguishing the nature of the fault through rectification. Moreover, reclosing in permanent faults could induce a secondary impact on the system. To solve the above problems, an adaptive reclosing scheme for cross-line faults on double-circuit wind power outgoing lines with shunt reactors is proposed. Firstly, a new tripping strategy and a single-side partial-phase reclosing method are proposed for multiple types of outgoing line faults, while, simultaneously, phase-to-phase coupling loops are established. Secondly, the criteria of fault nature are established based on the fault phase shunt reactor current and fault phase voltage characteristics, and transient faults are rapidly and accurately distinguished from permanent ones according to the criteria. Finally, the theoretical derivation and simulation experiments are conducted on the PSCAD/EMTDC platform to demonstrate that the proposed adaptive reclosing method is applicable to avoid the injection of negative sequence currents into wind turbines. Meanwhile, the success rate of reclosing for wind power outgoing line is significantly improved and the continuity of power transmission on the wind farm(s) is ensured.

Independently tunable dual Fano resonances based on plasmonic MIM Sagnac loop coupling Taiji resonator

In this paper, we first propose and demonstrate independently tunable dual Fano resonances based on a plasmonic structure composed of MIM (metal-insulator-metal) Sagnac loop with embedded Taiji resonator. An S-shaped crossover branch inside the Taiji ring resonator can tailor the propagating modes into their counter-propagating directions, finally tuning the number of whispering-gallery modes (WGMs) in Taiji resonator. Both Fano resonances originate from the interference between the discrete state generated from WGMs in Taiji resonator and continuous state from modes propagating in the plasmonic Sagnac loop. By stuffing a silver circle area (SCA) inside S-shaped branch, dual Fano resonances can be tuned independently as SCA has different sizes or locates at different places. Fano resonance would be influenced and shifted strongly when SCA locates at the energy intensity valley of WGM, while without any influence as SCA situates at the energy intensity peak of WGM. Thanks to the strong sub-wavelength light confinement of dual Fano resonances based on MIM plasmonic system, an optical refractometric sensor with figure of merit (FOM) of 100/RIU and high sensitivity of 1899 nm/RIU is demonstrated. Furthermore, this hybrid structure is also used for temperature sensing of ethanol with the maximal sensitivity of −0.793 nm/°C. This compact plasmonic Sagnac loop coupling Taiji resonator demonstrates impressive practical prospects for high-sensitivity biochemical sensors, nonlinear optics, and optical modulation.

Synchronously tunable combined four-channel ferrite filter

The original design of the synchronously tunable combined four-channel ferrite filter is given. It is a functional unit consisting of four microwave systems of ferrite filters with coupling loops (one such microwave system in each channel) and a common magnetic system for these filters, which ensures their synchronous tuning in the frequency range of 2-4 GHz. The structural solution of the microwave system in the form of a module allows one to obtain both a bandpass ferrite filter and a band-reject ferrite filter. The results of experimental research are provided. They showed that such a four-channel controllable ferrite filter has not only improved design and technological indicators but also a high decoupling between channels. It can be successfully used not only in measuring equipment but also in modern multichannel microwave communication equipment and radar.

Description of the State primary standard for length, velocity, and acceleration units at the oscillating movement of solid body NDETU AUV-04-2019

The article describes the state of metrological assurance in Ukraine, the field of vibration measurements, the composition of the State primary standard for length, velocity, and acceleration at oscillating movement NDETU AUV-04-2019, and its general characteristics and functioning principles. And attention is paid to the key comparisons in which this standard had taken part. The ways of standard upgrading are considered.

On the number of subproblem iterations per coupling step in partitioned fluid‐structure interaction simulations

AbstractIn literature, the cost of a partitioned fluid‐structure interaction scheme is typically assessed by the number of coupling iterations required per time step, while ignoring the internal iterations within the nonlinear subproblems. In this work, we demonstrate that these internal iterations have a significant influence on the computational cost of the coupled simulation. Particular attention is paid to how limiting the number of iterations within each solver call can shorten the overall run time, as it avoids polishing the subproblem solution using unconverged coupling data. Based on systematic parameter studies, we investigate the optimal number of subproblem iterations per coupling step. In addition, this work proposes a new convergence criterion for partitioned algorithms that is based solely on the number of subproblem iterations required to reach the subproblem residual tolerances and therefore does not require any additional convergence tolerance for the coupling loop.

Post-earthquake rapid assessment for loop system in substation using ground motion signals

This study proposes a rapid assessment framework for loop systems in substations after earthquakes, in which multiple one-to-one machine learning (ML) models are established targeting a series of electrical equipment in a loop system and predicting the seismic response levels using ground motion parameters. A multi-input-multi-output assessment model for the loop system is then developed by multi-objective optimization for the performance of various ML models, utilizing swarm intelligence evolution technology to tune the model’s internal architecture. A case analysis of an 800 kV filter loop system demonstrates the efficacy of this method. In this case, the integration of gradient boosting regression tree and non-dominated sorting genetic algorithm with an elite strategy is proposed. This approach not only simplifies the number of objects by addressing coupling loop systems as units but also requires only ground motion signals, thereby avoiding sensor installations on equipment and electromagnetic interference, making it particularly suitable for assisting post-earthquake emergencies in substations.

Design and analysis of a coupling coil structure for high‐efficiency wireless charging system for consumer electronics

SummaryThis paper introduces a novel type of coupling coil structure that can be used for wireless charging of consumer electronics. The coupling loop configuration includes an eight‐shaped transceiver coil and dual rectangular coils integrated on the printed circuit board (PCB). Moreover, when numerous transmitting coils of this structure are staged in parallel, it can sustain a consistent mutual inductance even when the receiver coil is not aligned, which can efficiently stabilize output power during charging. The article first models three different coil structures based on circuit theory and simulates their electromagnetic fields in commercial software and then performs a comparison among the three types of coils. Finally, it verifies the anti‐offset capability of the modified structure through a 25 W wireless power transmission experimental platform. The experimental outcomes are in accordance with the simulation and theoretical analysis, and compared with traditional dual‐transmitting coil structures, better overall power transmission efficiency has been achieved.

Multi-wavelength sub-100 Hz linewidth Brillouin fiber laser with cascaded SBS polarization parity-time symmetry

A multi-wavelength sub-100 Hz linewidth Brillouin fiber laser (BFL) with cascaded stimulated Brillouin scattering (SBS) polarization parity-time (PT) symmetry is proposed and experimentally investigated. Multi-order Stokes wave generation using a structure consisting of a main fiber ring (MFR) and a sub fiber loop (SFL). The MFR is used to excite the Stokes laser and to guarantee single longitudinal mode (SLM) operation of the generated stokes laser of each order and the SFL cascades each Stokes lasing emission to act as a Brillouin pump for the next order of Stokes generation. A Sagnac loop in the MFR consisting of optical coupler (OC), polarization beam splitter (PBS) and two polarization controllers (PCs), is used to achieve cascaded SBS polarization PT symmetry. By tuning the PC to control the polarization state of each order linearly polarized light injected into PBS at each order, thus controlling the gain and loss of the loop corresponding to the two backpropagating light waves. When the gain and loss of the coupling loops are the same in magnitude and greater than the coupling coefficient, the cascaded SBS polarization PT symmetry is broken, resulting in SLM operation for each order of Stokes waves. Experimental results reveal that thirteen Stokes waves were obtained from two different output ports at an erbium-doped fiber amplifier (EDFA) output power of 28 dBm. The measured linewidths at — 20 dB power were 0.34, 0.39, 0.33, 0.4, 0.39 and 0.43 kHz for the 1st-6th order Stokes emission, corresponding to linewidths of 17.1, 19.6, 16.6, 20.1 19.6 and 21.6 Hz, respectively, while the maximum side mode suppression ratios (SMSRs) were measured to be 47, 45, 49, 44, 41 and 41 dB for the 1st-6th order Stokes emission. Within 60 min of the stability experiment, the wavelength and power stability were ±2 pm and ±0.6 dB, respectively. Compared with previous studies, the present design guarantees the operation of SLM for each order of Stokes waves with sub-100 Hz laser linewidth.

Correlations of receptor desensitization of gain-of-function GABRB3 variants with clinical severity.

Genetic variants associated with developmental and epileptic encephalopathies have been identified in the GABRB3 gene that encodes the β3 subunit of GABAA receptors. Typically, variants alter receptor sensitivity to GABA resulting in either gain- or loss-of-function, which correlates with patient phenotypes. However, it is unclear how another important receptor property, desensitization, contributes to the greater clinical severity of gain-of-function variants. Desensitization properties of 20 gain-of-function GABRB3 variant receptors were evaluated using two-electrode voltage-clamp electrophysiology. The parameters measured included current decay rates and steady-state currents. Selected variants with increased or reduced desensitization were also evaluated using whole-cell electrophysiology in transfected mammalian cell lines. Of the 20 gain-of-function variants assessed, 13 were found to alter receptor desensitization properties. Seven variants reduced desensitization at equilibrium, which acts to worsen gain-of-function traits. Six variants accelerated current decay kinetics, which limits gain-of-function traits. All affected patients displayed severe clinical phenotypes with intellectual disability and difficult-to-treat epilepsy. Nevertheless, variants that reduced desensitization at equilibrium were associated with more severe clinical outcomes. This included younger age of first seizure onset (median 0.5 months), movement disorders (dystonia and dyskinesia), epilepsy of infancy with migrating focal seizures (EIMFS) and risk of early mortality. Variants that accelerated current decay kinetics were associated with slightly milder phenotypes with later seizure onset (median 4 months), unclassifiable developmental and epileptic encephalopathies or Lennox-Gastaut syndrome and no movement disorders. Our study reveals that gain-of-function GABRB3 variants can increase or decrease receptor desensitization properties and that there is a correlation with the degree of disease severity. Variants that reduced the desensitization at equilibrium were clustered in the transmembrane regions that constitute the channel pore and correlated with greater disease severity, while variants that accelerated current decay were clustered in the coupling loops responsible for receptor activation and correlated with lesser severity.

Analysis of coupled two-phase natural circulation loops by developing HEM and DFM based numerical models

The coupled two-phase natural circulation loop based passive systems find numerous applications, particularly in nuclear reactors where safety is paramount. However, the loops coupling, system conditions (specific to the reactor type), and inherent coupled loops feedback make their dynamics more complex. Hence, the models used should be capable of predicting such intricate coupled dynamics for precise forecasting of passive systems performance. With this objective, the present analyses deliberate the transients of such coupled two-phase loops linked to coupling configurations and operating conditions. Generalized two-phase models based on Homogeneous Equilibrium (HEM) and Drift Flux (DFM) with flashing, wall and fluid conduction, water-steam property formulation, etc., are developed and employed. Validation studies substantiate the prediction capability of these models for various cooler-heater orientations. Subsequently, predicted the start-up transients of vertically and horizontally coupled two-phase loops. The analyses revealed that coupling configurations, heater-cooler orientations and system conditions significantly influence the coupled loops. Further, the influences of various geometrical and operating parameters on the dynamics of coupled loops are investigated. It elucidated the differences in the parameter's effect on single-phase and two-phase coupled loops. The study also identified the vital parameters strongly influencing the coupled loops based on sensitivity analysis. The models and findings will be applied to evaluate the performance of coupled loop-based passive safety systems in nuclear reactors.

High-Gain and Wideband Circularly Polarized Endfire Leaky-Wave Antenna Array Based on the Complementary Dipole

A circularly polarized (CP) endfire leaky-wave antenna (LWA) array with the merits of high-gain and broad operation band is proposed in this communication. This array configuration is composed of double-row antenna cells arranged linearly, which derives from the performance of the complementary dipole (loop and electric dipole). By introducing the coupling loop and the electric dipole along both side of a metallic parallel strip line (PSL), the effective radiation is generated from this structure due to the periodic perturbation. Based on the intrinsic 90° phase differences of the complementary dipole, CP performance is easily achieved by turning the antenna unit size reasonably. Similar to the yagi antenna, this linearly antenna array achieves an endfire radiation. A fabricated prototype has verified the design concept, which shows that the proposed antenna has a relative impedance bandwidth of 51.1%, 3dB axial ratio (AR) bandwidth of 25%, and the gain of 1.1-13.59dBi within the operation band.

An ultra‐wideband MIMO system with multi‐loop mode for full‐screen smartphone applications

AbstractIn this letter, an ultra‐wideband (UWB) eight‐element multiple‐input multiple‐output (MIMO) antenna system with multi‐loop modes for fifth‐generation (5G) smartphones is presented. The antenna unit has a simple structure and is composed of an inverted U‐shaped feeding strip and an L‐shaped grounding radiation strip with a hollow out in the middle. Owing to the generation of two coupling loop modes, the working bandwidth of the proposed antenna unit covers 3.2−6.4 GHz. Besides, the simulated and measured results show that the isolation between any two antennas is better than 12.0 dB, and the total efficiency of each element is higher than 50%. Meanwhile, the measured radiation pattern, envelope correlation coefficients, channel capacity loss, mean effective gain, and diversity gain are also given in this letter. The above results demonstrate that the MIMO system has the advantages of simple structure, convenient manufacture, and superior performance.

Multi-Amplification-Channel Active EMI Filter Based on Period Spread-Spectrum PWM for Common-Mode EMI Suppression

Due to the existing coupling loop between the motor drive system and the ground, when switching devices in the drive system operate at a high speed, common-mode (CM)-conducted electromagnetic interference (EMI) is generated in the loop. The electromagnetic environment quality of the motor and peripheral equipment is reduced. As a small and lightweight EMI suppression device, the active EMI filter (AEF) can be used in the motor drive system to suppress the CM-conducted EMI. As the unity gain bandwidth of the operational amplifier (OPAMP) in the AEF is fixed, the CM-conducted EMI suppression effect of the AEF is poor. To solve this problem, the multiple-amplification-channel method is used to spread the frequency range of the CM voltage that the AEF can sense; therefore, the frequency of the compensation current output using the AEF is more complete, and a better CM-conducted EMI attenuation effect is obtained. At the same time, a combination of the period frequency carrier modulation (PCFM) and the multi-amplification-channel AEF is adopted so that the CM-conducted EMI in the whole EMI frequency range of the motor drive system is effectively suppressed.

Mechano-electrical interactions and heterogeneities in wild-type and drug-induced long QT syndrome rabbits.

Electromechanical reciprocity - comprising electro-mechanical (EMC) and mechano-electric coupling (MEC) - provides cardiac adaptation to changing physiological demands. Understanding electromechanical reciprocity and its impact on function and heterogeneity in pathological conditions - such as (drug-induced) acquired long QT syndrome (aLQTS) - might lead to novel insights in arrhythmogenesis. Our aim is to investigate how electrical changes impact on mechanical function (EMC) and vice versa (MEC) under physiological conditions and in aLQTS. To measure regional differences in EMC and MEC in vivo, we used tissue phase mapping cardiac MRI and a 24-lead ECG vest in healthy (control) and IKr-blocker E-4031-induced aLQTS rabbit hearts. MEC was studied in vivo by acutely increasing cardiac preload, and ex vivo by using voltage optical mapping (OM) in beating hearts at different preloads. In aLQTS, electrical repolarization (heart rate corrected RT-interval, RTn370) was prolonged compared to control (P<0.0001) with increased spatial and temporal RT heterogeneity (P<0.01). Changing electrical function (in aLQTS) resulted in significantly reduced diastolic mechanical function and prolonged contraction duration (EMC), causing increased apico-basal mechanical heterogeneity. Increased preload acutely prolonged RTn370 in both control and aLQTS hearts (MEC). This effect was more pronounced in aLQTS (P<0.0001). Additionally, regional RT-dispersion increased in aLQTS. Motion-correction allowed us to determine APD-prolongation in beating aLQTS hearts, but limited motion correction accuracy upon preload-changes prevented a clear analysis of MEC ex vivo. Mechano-induced RT-prolongation and increased heterogeneity were more pronounced in aLQTS than in healthy hearts. Acute MEC effects may play an additional role in LQT-related arrhythmogenesis, warranting further mechanistic investigations. KEY POINTS: Electromechanical reciprocity comprising excitation-contraction coupling (EMC) and mechano-electric feedback loops (MEC) is essential for physiological cardiac function. Alterations in electrical and/or mechanical heterogeneity are known to have potentially pro-arrhythmic effects. In this study, we aimed to investigate how electrical changes impact on the mechanical function (EMC) and vice versa (MEC) both under physiological conditions (control) and in acquired long QT syndrome (aLQTS). We show that changing the electrical function (in aLQTS) results in significantly altered mechanical heterogeneity via EMC and, vice versa, that increasing the preload acutely prolongs repolarization duration and increases electrical heterogeneity, particularly in aLQTS as compared to control. Our results substantiate the hypothesis that LQTS is an ‛electro-mechanical', rather than a 'purely electrical', disease and suggest that acute MEC effects may play an additional role in LQT-related arrhythmogenesis.