Tuning Speed Research Articles

Switched-Capacitor Tuning for Three-Phase Wireless Power Receiver Based on Perturbation and Observation Method

To realize the tuning of three-phase dynamic wireless power receivers for rail vehicles, a non-real-time static self-tuning scheme based on the switched capacitor and the perturbation and observation (P&O) method is studied. First, the reactance regulation characteristics of the parallel and the series switched capacitor are discussed and compared. Then, to avoid the sophisticated mistuning detection, in the case of only observing the output voltage, the feasibility of using the P&O method to tune three phases of the receiver sequentially is analyzed. Furthermore, theoretical analysis shows that the switched capacitor can also be used to control the current phase difference between the three phases. Thereby, by introducing the current phase difference control, a fast three-phase simultaneous tuning strategy is proposed without additional hardware. Afterward, the self-tuning control scheme for the star-connected series-compensated receiver with the parallel and series switched capacitor is design in detail and be applied to a scaled-down prototype of a three-phase dynamic wireless power transfer system for verification. The result shows that the receiver can be tuned within the ±5% deviation of the main compensation capacitance, and the tuning speed of the proposed simultaneous tuning of three phases is about three times that of the sequence tuning.

Physical work principles of digital computational synthesizers of multiphase signals

Modern systems of radio engineering systems are very widely used in radar and radio communications. An important component of the work of radio systems is the creation of diagnostic equipment with high resolution, noise immunity, improved security and reliability, which become more accessible with the advent of digital computer frequency synthesizers. Digital computer synthesizers using the direct digital signal synthesis method are the main nodes of modern diagnostic equipment for radar and radio communication systems. The article considers a number of advantages of digital computing synthesizers, which include a wide range of synthesized frequencies, an extremely small step of the frequency grid, extremely fast frequency tuning speed, phase continuity during frequency tuning, low phase noise, a simple algorithm for generating complex signals, the possibility of independent amplitude control, phase and frequency of the synthesized signal. The principles of construction and structural and circuitry solutions of digital computational synthesizers based on the method of direct digital synthesis of frequencies and signals are given. The principle of constructing structures of digital multiphase signal synthesizers is proposed, in which the initial phases of the synthesized signals can be set in software. Structural diagrams of digital computational synthesizers based on digital code storage devices and with an M-shaped law of frequency variation which allow synthesizing signals with amplitude, frequency and phase modulation in the frequency range from 0.001 to 400 MHz are presented.

A Novel Moment of Inertia Identification Strategy for Permanent Magnet Motor System Based on Integral Chain Differentiator and Kalman Filter

In a motor control system, the parameters tuning of speed and position controller depend on the value of the moment of inertia. A new moment of inertia identification scheme for permanent magnet motor system was proposed in this paper. This is an extension of the existing acceleration deceleration methods, which solves the large moment of inertia identification error caused by variable angular acceleration, large calculation error of inertia torque, and large measurement noise in the acceleration process. Based on the fact that the angular acceleration is not constant and the sampling signal is noisy, the integral chain differentiator was used to calculate the instantaneous angular acceleration at any time and suppress the sampling signal noise at the same time. The error function with instantaneous angular acceleration and inertia torque as parameters was designed to estimate the moment of inertia. In order to calculate the inertia torque accurately, viscous friction torque was considered in the calculation of inertia torque, and Kalman filter was used to estimate the total load torque to solve the problem of under rank of motor motion equation. Simulation and experimental results showed that the proposed method could effectively identify the moment of inertia in both noisy and noiseless environments.

Functional Differentiation of Mouse Visual Cortical Areas Depends upon Early Binocular Experience.

The mammalian visual cortex contains multiple retinotopically defined areas that process distinct features of the visual scene. Little is known about what guides the functional differentiation of visual cortical areas during development. Recent studies in mice have revealed that visual input from the two eyes provides spatiotemporally distinct signals to primary visual cortex (V1), such that contralateral eye-dominated V1 neurons respond to higher spatial frequencies than ipsilateral eye-dominated neurons. To test whether binocular visual input drives the differentiation of visual cortical areas, we used two-photon calcium imaging to characterize the effects of juvenile monocular deprivation (MD) on the responses of neurons in V1 and two higher visual areas, LM (lateromedial) and PM (posteromedial). In adult mice of either sex, we find that MD prevents the emergence of distinct spatiotemporal tuning in V1, LM, and PM. We also find that, within each of these areas, MD reorganizes the distinct spatiotemporal tuning properties driven by the two eyes. Moreover, we find a relationship between speed tuning and ocular dominance in all three areas that MD preferentially disrupts in V1, but not in LM or PM. Together, these results reveal that balanced binocular vision during development is essential for driving the functional differentiation of visual cortical areas. The higher visual areas of mouse visual cortex may provide a useful platform for investigating the experience-dependent mechanisms that set up the specialized processing within neocortical areas during postnatal development.SIGNIFICANCE STATEMENT Little is known about the factors guiding the emergence of functionally distinct areas in the brain. Using in vivo Ca2+ imaging, we recorded visually evoked activity from cells in V1 and higher visual areas LM (lateromedial) and PM (posteromedial) of mice. Neurons in these areas normally display distinct spatiotemporal tuning properties. We found that depriving one eye of normal input during development prevents the functional differentiation of visual areas. Deprivation did not disrupt the degree of speed tuning, a property thought to emerge in higher visual areas. Thus, some properties of visual cortical neurons are shaped by binocular experience, while others are resistant. Our study uncovers the fundamental role of binocular experience in the formation of distinct areas in visual cortex.

Golden eagle optimizer: A nature-inspired metaheuristic algorithm

This paper proposes a nature-inspired swarm-based metaheuristic for solving global optimization problems called Golden Eagle Optimizer (GEO). The core inspiration of GEO is the intelligence of golden eagles in tuning speed at different stages of their spiral trajectory for hunting. They show more propensity to cruise around and search for prey in the initial stages of hunting and more propensity to attack in the final stages. A golden eagle adjusts these two components to catch the best possible prey in feasible region the shortest possible time. This behavior is mathematically modeled to highlight exploration and exploitation for a global optimization method. The performance of the proposed algorithm is tested and confirmed using 33 benchmark test functions and a scalability test. Results were compared to that of six other well-known algorithms, which revealed GEO’s superiority, which indicates that it can find the global optimum and avoid local optima effectively. The Multi-Objective Golden Eagle Optimizer (MOGEO) is also proposed to solve multi-objective problems. The performance of MOGEO is also tested and verified on ten multi-objective benchmark functions. Results were compared to that of two other multi-objective algorithms, which showed that it can approximate true Pareto optimal solutions better than the other two algorithms. The software (toolbox) and source code for GEO and MOGEO are also provided, which are publicly available.

Modeling and Speed Tuning of a PMSM with Presence of Fissure Using Dragonfly Algorithm

This paper presents a robust trajectory tracking control for a Permanent Magnet Synchronous Motor (PMSM) with consideration a fault, parametric uncertainties and external disturbances by effectively integrating robust optimal linear quadratic control. One kind of fault is considered in the machine, particularly the presence of fissure rotor. The dynamic model of the PMSM with the presence of fissure presents highly non-linear behaviors, which means that tuning is quite complicated, which the tuning was chosen through swarm intelligence optimization (Dragonfly Algorithm). A sensitivity analysis is carried out, in order to limit the search range to minimize the evaluation time. This methodology was used to diminish these defects during motor operation. Simulation results show that the optimal linear quadratic control method has a robust fault-tolerant performance.

A novel deep interval prediction model with adaptive interval construction strategy and automatic hyperparameter tuning for wind speed forecasting

Wind energy is a renewable energy source with great development potential. However, its inherent instability and randomness have brought great challenges to the maximum utilization of wind energy. Wind speed forecasting is one of the most effective ways to mitigate these challenges, which plays an important role in the operational management and decision-making of wind power system operators. In this study, a novel wind speed interval prediction model based on gated recurrent unit, Variational Mode Decomposition, and Particle Swarm Optimization was proposed. The original wind speed sequence was decomposed into several smoother sub-sequences through the Variational Mode Decomposition algorithm, and corresponding sub-models were established based on the gated recurrent unit. To better supervise the training process, artificial prediction intervals with adaptive adjustment strategies were devised. Moreover, the Particle Swarm Optimization algorithm was adopted to search for the optimal superposition weights of PIs to achieve the integral optimization of the model. The qualitative and quantitative performance of the proposed method has been fully tested and verified in a series of real cases.

Enhanced terahertz focusing for a graphene-enabled active metalens.

Graphene-based terahertz (THz) metasurfaces have the advantages of ultra-small thickness, electrical tunability, and fast tuning speed. However, many such structures suffer low efficiency, especially for transmissive devices. Here we propose a hybrid structure for focusing THz waves with tunability and enhanced focusing efficiency, which is composed of a graphene-loaded metallic metasurface sandwiched by two mutually orthogonal gratings. Experimental results show that due to the multi-reflection between the metasurface layer and the grating layer, the focusing efficiency is enhanced by 1.8 times, and the focal length of the metalens is increased by 0.61 mm when the applied gate voltage on the graphene is increased from 0 V to 1.4 V. We hope the proposed structure may open a new avenue for reconfigurable THz metasurfaces with high efficiencies.

Electromagnetic radiation-based IC device identification and verification using deep learning

The electromagnetic radiation of electronic equipment carries information and can cause information leakage, which poses a serious threat to the security system; especially the information leakage caused by encryption or other important equipment will have more serious consequences. In the past decade or so, the attack technology and means for the physical layer have developed rapidly. And system designers have no effective method for this situation to eliminate or defend against threats with an absolute level of security. In recent years, device identification has been developed and improved as a physical-level technology to improve the security of integrated circuit (IC)-based multifactor authentication systems. Device identification tasks (including device identification and verification) are accomplished by monitoring and exploiting the characteristics of the IC’s unintentional electromagnetic radiation, without requiring any modification and process to hardware devices, thereby providing versatility and adapting existing hardware devices. Device identification based on deep residual networks and radio frequency is a technology applicable to the physical layer, which can improve the security of integrated circuit (IC)-based multifactor authentication systems. Device identification tasks (identification and verification) are accomplished by passively monitoring and utilizing the inherent properties of IC unintended RF transmissions without requiring any modifications to the analysis equipment. After the device performs a series of operations, the device is classified and identified using a deep residual neural network. The gradient descent method is used to adjust the network parameters, the batch training method is used to speed up the parameter tuning speed, the parameter regularization is used to improve the generalization, and finally, the Softmax classifier is used for classification. In the end, 28 chips of 4 models can be accurately identified into 4 categories, then the individual chips in each category can be identified, and finally 28 chips can be accurately identified, and the verification accuracy reached 100%. Therefore, the identification of radio frequency equipment based on deep residual network is very suitable as a countermeasure for implementing the device cloning technology and is expected to be related to various security issues.

MEMS-actuated metasurface Alvarez lens

Miniature lenses with a tunable focus are essential components for many modern applications involving compact optical systems. While several tunable lenses have been reported with various tuning mechanisms, they often face challenges with respect to power consumption, tuning speed, fabrication cost, or production scalability. In this work, we have adapted the mechanism of an Alvarez lens – a varifocal composite lens in which lateral shifts of two optical elements with cubic phase surfaces give rise to a change in the optical power – to construct a miniature, microelectromechanical system (MEMS)-actuated metasurface Alvarez lens. Implementation based on an electrostatic MEMS generates fast and controllable actuation with low power consumption. The utilization of metasurfaces – ultrathin and subwavelength-patterned diffractive optics – as optical elements greatly reduces the device volume compared to systems using conventional freeform lenses. The entire MEMS Alvarez metalens is fully compatible with modern semiconductor fabrication technologies, granting it the potential to be mass-produced at a low unit cost. In the reported prototype operating at 1550 nm wavelength, a total uniaxial displacement of 6.3 µm was achieved in the Alvarez metalens with a direct-current (DC) voltage application up to 20 V, which modulated the focal position within a total tuning range of 68 µm, producing more than an order of magnitude change in the focal length and a 1460-diopter change in the optical power. The MEMS Alvarez metalens has a robust design that can potentially generate a much larger tuning range without substantially increasing the device volume or energy consumption, making it desirable for a wide range of imaging and display applications.

Electro-optically tunable laser with ultra-low tuning power dissipation and nanosecond-order wavelength switching for coherent networks

The huge amount of data traffic behind the rapid growth of cloud computing is putting pressure on the operation of mobile fronthauls and data center networks so there is a need to improve their power consumption and latency. We developed an electro-optically tunable laser diode employing a tunable filter that is practically tuned even with small refractive index change of the electro-optic effect. The laser shows a small tuning power dissipation of less than 10 mW for a practical tuning range of over 35 nm with a linewidth of about 350 kHz. We also achieved high-speed optical switching of less than 50 ns for 100 Gb/s coherent signals. In addition to its application in optical communications, the electro-optically tunable laser diode is also beneficial to laser sensing applications because its higher tuning speed increases the time resolution of the sensing system. Furthermore, a narrow linewidth, conventionally difficult to reconcile with high-speed tuning, can also enable a longer sensing distance and/or a higher signal-to-noise ratio when using coherent detection. Our result shows that we can use the electro-optic effect to overcome the limitations of conventional tunable laser diodes and drastically change optical communications and laser sensing systems.

ANT COLONY OPTIMIZATION PARAMETER SELECTION FOR SHORTEST PATH PROBLEM

Abstract. The shortest path problem has been studied to be solved through diverse deterministic and also stochastic approaches such as Ant Colony Optimization. One of the most challenging issues with the implication of Ant Colony Optimization to solve the shortest path problem is parameter selection and tuning which is found crucial to improve the computational performance of problem-solving. To tune parameters, it is vital to observe the response of each parameter to different values and study their effect on the final results. In this research, two experiments are designed and conducted to study the behavior of parameters in terms of generated results and computational performance. In the first experiment, evaporation, updating, and transition rule parameters are studied by iterative execution of shortest path generation between nodes considering different parameter values. In the second experiment, the number of initial ants is studied. Inspecting the results, it is observed that to avoid premature stagnation decreasing α value is recommended. On the other hand, ρ is observed to be considered for tuning of speed and number of diffusions of the algorithm. Moreover, it is realized that a high Q value would result in more correct results. Inspecting the initial number of ants, a threshold is realized where increasing the number of ants over this threshold would drastically result in more optimized paths.

Silk Fibroin 3D Microparticle Scaffolds with Bioactive Ceramics: Chemical, Mechanical, and Osteoregenerative Characteristics

Preparation of 3D scaffolds for bone tissue engineering (BTE) is a challenging task as it requires appropriate pore size and porosities, mechanical properties, and controlled bioerosion rate. The focus of this work is the fabrication of silk fibroin (SF) 3D microparticle scaffolds with the incorporation of hydroxyapatite (HA) and calcium sulfate (CaS) as bioceramics. Physicochemical characterization shows ≈30% filler loading and ≈40% optimum porosity with >100 μm pore size for these filled/unfilled scaffolds. Nanoindentation studies show improved Young's modulus at microparticle level with the incorporation of bioceramics. SF‐HA scaffolds showed three fold increase in Young's modulus, whereas SF‐CaS showed two fold increase. In vitro bioerosion study results in early bioerosion with SF‐CaS scaffold, whereas prolonged bioerosion with SF‐HA scaffold. In vitro osteoregenerative potential is analyzed by estimating alkaline phosphatase (ALP), bone morphogenetic protein‐2 (BMP‐2), and osteocalcin (OCN). SF CaS supports early stage differentiation while SF 50% HA predominantly supports late stage. The expression of TNF‐α suggests a reduced risk of immune rejection. This work, therefore, concludes that although SF supports bone tissue regeneration, the choice of bioceramic enhances the applicability in various clinical scenarios by providing a controlled bioerosion rate, tunable speed of osteoregeneration, and improved load bearing capacities.

Nodes of Ranvier during development and repair in the CNS.

Saltatory conduction of action potentials along myelinated axons depends on the nodes of Ranvier - small unmyelinated axonal domains where voltage-gated sodium channels are concentrated. Our knowledge of the complex molecular composition of these axonal domains continues to accumulate, although the mechanisms of nodal assembly, which have been elucidated in the PNS, remain only partially understood in the CNS. Besides the key role of the nodes in accelerating conduction, nodal variations are thought to allow the fine tuning of axonal conduction speed to meet information processing needs. In addition, through their multiple glial contacts, nodes seem to be important for neuron-glia interactions. As we highlight in this Review, the disorganization of axonal domains has been implicated in the pathophysiology of various neurological diseases. In multiple sclerosis, for example, nodal and perinodal disruption following demyelination, with subsequent changes in ion channel distribution, leads to altered axonal conduction and integrity. The nodal clusters regenerate concurrently with but also prior to remyelination, allowing the restoration of axonal conduction. In this article, we review current knowledge of the organization and function of nodes of Ranvier in the CNS. We go on to discuss dynamic changes in the nodes during demyelination and remyelination, highlighting the impact of these changes on neuronal physiology in health and disease as well as the associated therapeutic implications.

Broadband Light Amplitude Tuning Characteristics of SnSe2 Coated Microfiber

Broadband light amplitude tuning characteristics are demonstrated in a 2-D tin diselenide (SnSe2) nanosheets coated microfiber (MF) structure (SnSe2CMF). Due to the strong absorption characteristics of SnSe2 in broadband wavelengths, the transmitted optical power (TOP) of SnSe2CMF can be tuned by external pump lights with different wavelengths (405, 532, and 660 nm) over a broadband spectrum (1520–1620 nm). Five wavelengths are extracted in order to investigate the tuning performance. The TOP of SnSe2CMF increases with the pump light power and a maximum tuning efficiency of ∼0.3074 dB/mW is achieved. In terms of tuning speed, the minimum response time is ∼3.7/3.9 ms. The experimental results have qualitatively good agreement with the simulations predicted by FEM models. The demonstrated structure has the advantages of broad tuning bandwidth and high tuning efficiency. Therefore, it might be a promising candidate for building high performance broadband fiber-optic sensors and modulators.

Electro-Optically Switchable Optical True Delay Lines of Meter-Scale Lengths Fabricated on Lithium Niobate on Insulator Using Photolithography Assisted Chemo-Mechanical EtchingSupported by the National Key R&D Program of China (Grant No. 2019YFA0705000), the National Natural Science Foundation of China (Grant Nos. 11734009, 61590934, and 11874375), the Strategic Priority Research Program of CAS (Grant No. XDB16030300), and the Key Project of the

Optical true delay lines (OTDLs) of low propagation losses, small footprints and high tuning speeds and efficiencies are of critical importance for various photonic applications. Here, we report fabrication of electro-optically switchable OTDLs on lithium niobate on insulator using photolithography assisted chemo-mechanical etching. Our device consists of several low-loss optical waveguides of different lengths which are consecutively connected by electro-optical switches to generate different amounts of time delay. The fabricated OTLDs show an ultra-low propagation loss of ∼ 0.03 dB/cm for waveguide lengths well above 100 cm.

The Structure of the Exciter of a Dielkometric System for Research of Biological Objects Using an Adaptive Interference Canceller

An important task in the development of sources of electromagnetic vibrations used in the design of dielkometrical systems for biological objects is to reduce the level of interference of the electromagnetic vibrations source in the output spectrum. Methods for suppressing side components in the output spectrum conflict with the dynamic characteristics of the electromagnetic vibrations source, in particular, they do not meet the requirements for the tuning speed in the specified wave ranges. (Research purpose) The research purpose is in developing the basic structure of the exciter of the dielkometric system for the study of biological objects, allowing obtaining previously unacceptable values of suppression of the comparison frequency and its harmonics. (Materials and methods) Authors applied the compensation method to obtain the required spectral and dynamic characteristics of the electromagnetic vibrations source. The article sets the problem of adaptive noise compensation, which was solved using a quasi-optimal method, the method of the minimum of the average square error. (Results and discussion) The article proposes the basic structure of the exciter of the dielkometric system for the study of biological objects. It was shown that the adaptive method results in suppression of side components in the spectrum of the output signal source while maintaining the required speed. The spectral components of the output signal of the electromagnetic source were studied using a functional method. It was found that there is an effective convergence of the transfer functions of adaptive filters of the adaptive compensator of side components to the nonlinear transfer function of the corresponding orders of the dynamic system. (Conclusions) The article presents the developed structure of the exciter of the dielkometrical system using an adaptive compensator of side components, which allows to obtain previously unacceptable values of suppression of the comparison frequency and its harmonics. It was found that the use of this structure of the exciter will improve the dynamic characteristics of the dielkometrical system as a whole. It was found that the use of adaptive filters increases the speed of the exciter by 5-10 times.

Pump-Color Selective Control of Ultrafast All-Optical Switching Dynamics in Metaphotonic Devices.

Incorporating active materials into metamaterials is expected to yield exciting advancements in the unprecedented versatility of dynamically controlling optical properties, which sheds new light on the future optoelectronics. The exploration of emerging semiconductors into terahertz (THz) meta‐atoms potentially allows achieving ultrafast nanodevices driven by various applications, such as biomedical sensing/imaging, ultrawide‐band communications and security scanners. However, ultrafast optical switching of THz radiation is currently limited to a single level of tuning speed, which is a main hurdle to achieve multifunctionalities. Here, a hybrid metadevice which can realize the pump‐wavelength controlled ultrafast switching response by the functionalization of double photoactive layers is demonstrated experimentally. A whole cycle of electromagnetically induced transparency switching with a half‐recovery state changes from 0.78 ns to 8.8 ps as pump wavelength varies from near infrared to near ultraviolet regions. The observed pump‐color selective switching speed changing from nanosecond scale to picosecond scale is ascribed to the wavelength‐dependent penetration length of Ge and the contrasting defect states between noncrystalline Ge and epitaxial Si layers. It is believed that the schemes regarding pump‐color controllable ultrafast switching behavior introduced here can inspire more innovations across the field of ultrafast photonics and can boost the reconfigurable metamaterial applications.

Ultrafast and wide tunable VCSEL using graphene passive cavity

A novel approach for achieving ultrafast and wide tunable vertical-cavity surface-emitting lasers (VCSELs) is presented. The design is based on incorporating multiple graphene flakes separated by SiO2 dielectric in a λ/2 cavity and placing multiquantum wells in one of the quarter wave layers of the bottom mirrors. The device concept enhances both the wavelength tuning range and tuning speed which is attractive for many photonic applications. By applying a gate voltage on the graphene flakes, the effective refractive index of the cavity can be changed with ultrahigh speed. We have shown that 2 graphene flakes inside a 5 µm-diameter passive cavity provides tuning speed as high as 32 GHz and wavelength tuning range of 3.8 nm. The tuning speed increases to 52 GHz when the device diameter is reduced to 3 µm. The effect of spacer thickness and the number of graphene flakes on the performance characteristics of the device is investigated. Our analysis shows that tuning speed as high as 2 GHz and wavelength tuning range of ~ 12 nm is obtained for VCSEL that incorporates 6 graphene flakes separated by 10 nm SiO2 spacers and biased in parallel. The tuning speed can be increased to ~ 16 GHz when the flakes are biased in series at the expense of higher gate voltage. A tradeoff between the wavelength tuning range and the tuning speed is obtained.

Wideband Signal Analyzer Based on Time-Interleaved ADCs with Digital Calibration

This paper presents a novel architecture of wideband signal analyzer based on time-interleaved ADCs. Architecture of signal analyzer include improved method of digital calibration of ADC channels operating in the time-interleaved mode of input signals. This method is based on the least squares method. The advantage of the proposed method is high speed and high accuracy of ADC channels tuning in comparison with the majority of existing methods, which are based on the least squares method. The results of simulation modeling of the proposed method, including spectral analysis of the output signal before and after calibration, are presented. The comparison of the proposed method with existing methods is performed.