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This article proposes an isolated high‐efficiency resonant LED driver with wide‐input voltage range. The proposed converter is developed by integrating LCC resonant converter and buck‐boost converter. In this topology, the LCC network provides many features including the integration of buck‐boost filter inductor and the transformer magnetizing inductance. In addition, the LCC network provides zero voltage switching (ZVS) operation of the main switches and zero current switching (ZCS) operation of the rectifier diodes over a wide variation of duty cycle operation. Also, load‐independent output current characteristic with improved efficiency is obtained at the resonant frequency operation which is well‐suited for LED applications. Other topology variations of the proposed converter generating step‐up and step‐down voltage gains are introduced for applications with different input voltage ranges. To validate the theoretical analysis and LED driver operation, a 50 W laboratory prototype of the proposed LED driver is implemented for the wide input voltage of 18–40 V to deliver 500 mA output current to a string of 1–30 LEDs, which corresponds to an output voltage range of 3.3–100 V. [ABSTRACT FROM AUTHOR]

Abstract A novel magnetic coupling resonance wireless power transfer (MCR‐WPT) system, which has constant‐current (CC) and constant‐voltage (CV) output characteristics suiting for batteries charging, is proposed in this paper. The hybrid compensation topology is adopted; in detail, the LCL‐P circuit topology is used in the CC mode, while the LCL‐S topology is used in the CV mode. Since the switchable components are only located at the receiving side of WPT, the switching can be controlled by the receiving side based on the batteries’ state without data communication between transmitting side and receiving side. Furthermore, an adjustable frequency tuning method which is based on proportion integration (PI) closed‐loop controlled by the transmitting side is applied to maximize the current of the transmitting coil. This method also can solve the frequency splitting problem, improving the stability and power of the system while the distance of the two sides changes. The performance of the proposed WPT system is verified by simulation and experiments. The experiment results show that the load current variation is less than 3% in the CC mode and the load voltage changes less than 5% in the CV mode, as the load resister changes from 5 to 20 Ω.

A novel magnetic coupling resonance wireless power transfer (MCR‐WPT) system, which has constant‐current (CC) and constant‐voltage (CV) output characteristics suiting for batteries charging, is proposed in this paper. The hybrid compensation topology is adopted; in detail, the LCL‐P circuit topology is used in the CC mode, while the LCL‐S topology is used in the CV mode. Since the switchable components are only located at the receiving side of WPT, the switching can be controlled by the receiving side based on the batteries' state without data communication between transmitting side and receiving side. Furthermore, an adjustable frequency tuning method which is based on proportion integration (PI) closed‐loop controlled by the transmitting side is applied to maximize the current of the transmitting coil. This method also can solve the frequency splitting problem, improving the stability and power of the system while the distance of the two sides changes. The performance of the proposed WPT system is verified by simulation and experiments. The experiment results show that the load current variation is less than 3% in the CC mode and the load voltage changes less than 5% in the CV mode, as the load resister changes from 5 to 20 Ω. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a fully soft switched high step‐up DC–DC converter based on quasi‐Z‐source converter. The voltage gain is boosted by combining coupled inductors and switched capacitor techniques. Moreover, a ZVT cell comprising of only a single switch and an inductor coupled to the quasi‐Z‐source inductor is utilized to reduce the magnetic cores and realize soft switching for all semiconductors without imposing any extra voltage or current stress on the converter elements. The main switch operates at zero voltage switching and zero current switching (ZCS) at turn‐on which is independent of the load and duty cycle variations. Hence, soft switching condition for the main switch at turn‐off is easily provided by a snubber capacitor. In addition, the reverse recovery problem of all the converter diodes is significantly mitigated by ZCS at turn‐off while the continuous current at the input source is maintained. In order to verify the theoretical analysis and the proposed converter operation, a converter prototype is implemented at 300 W and 100 kHz. Finally, a comprehensive comparison is performed between the proposed converter and other high step‐up converters based on quasi‐Z‐source structure, to demonstrate the merits of the proposed converter.

Abstract An ultra‐low quiescent current tri‐mode DC–DC boost converter is proposed in this paper, which can efficiently handle loads from 1 μA to 300 mA, providing 5‐V output from 3 to 4.2‐V input. Hysteresis current mode control is adopted to realize seamless mode switching between continuous conduction mode (CCM) and discontinuous conduction mode (DCM). In order to deal with the light load situation, this paper proposes a quasi burst mode (QBM). In this mode, most of the modules are turned off and only the QBM controller, low‐power current bias and sample and hold circuit are retained, which significantly reduces the static current of the converter, and thus improves the light load efficiency. Meanwhile, the average current of error amplifier and comparator are reduced significantly by dynamic biasing. Finally, the efficiency of the converter is greatly improved and kept at a reasonable output ripple. The proposed converter is implemented in a 0.13‐μm BCD process design and manufacturing. The test results show that the quiescent current of the converter is only 780 nA, which can achieve a peak efficiency of 95.6%, and ensure that the efficiency is maintained above 80% in the load range of 10 μA to 300 mA.

Abstract This paper aims to comprehensively analyze, critically discuss, and provide a step‐by‐step design guideline for a previously proposed Modified Switched‐Inductor type Buck‐Boost (MSIBB) converter which is based on a boost converter. The MSIBB converter is originally based on switched‐inductor phenomena whereby two inductors are switched in a proper sequence to ensure appreciable buck as well as boost characteristics. Appreciable buck and boost characteristics are desirable specifically in low power applications. In regulated low power applications, DC‐DC switching power converters undergo frequent mode‐shift from buck to boost, and vice versa. At the overlap between input/output voltage, the converters efficiency does not suffer significantly, but the wide input‐voltage operating area compels the regulated converters to operate at extreme values of the duty cycle, that is, close to 0 and 1, which causes lower efficiency. A high‐efficiency switching converter is required specifically for low‐power applications that can ensure voltage step‐up and step‐down without resorting to operating at extreme values of the duty‐cycle. In this perspective, switched‐inductors based converter, termed as MSIBB converter, was previously proposed. The MSIBB converter exhibits appreciable voltage‐gain, and experiences lesser current/voltage stress on the semiconductor components. In particular, it has comparable Maximum Switch Stress Factor that generally translates to alleviated switch conduction and switching losses. Besides, the inductors minimum peak stored energy is comparatively lower, reflecting reduced physical size of the inductors as well as reduced onboard losses, and therefore better caters to low power applications. Detailed analysis of the converter and step‐by‐step approach for design example, and comparative analysis are carried out, besides providing some experimental results from the previously proposed converter.

Abstract A fully soft switched high step‐up/down bidirectional converter is presented in this paper. The high voltage conversion ratio is achieved by a pair of coupled inductors along with a switched capacitor while all active switches operate at zero voltage switching. To provide soft switching condition for the main switches and absorb the leakage inductance energy of coupled inductors, active clamp circuits are utilized for both operating modes. Furthermore, all active switches body diodes which are utilized as converter diodes turn off at zero current switching (ZCS) and thus, the reverse recovery problem is eradicated. Additionally, the voltage stress of the main switches is reduced in comparison with the basic bidirectional buck/boost converter and thus, their drain‐source resistance is relatively lower which leads to considerably lower conduction loss. All the mentioned advantages along with relatively low number of components contribute to the converter efficiency. Theoretical analysis of the proposed converter is presented in detail for both operating modes and the experimental results from the implementation of a 300 W prototype circuit confirm the validity of the converter performance. A comprehensive comparison table between the proposed converter and the recent counterpart bidirectional converters is presented to demonstrate the converter advantages.

This paper presents a fully soft switched high step‐up DC–DC converter based on quasi‐Z‐source converter. The voltage gain is boosted by combining coupled inductors and switched capacitor techniques. Moreover, a ZVT cell comprising of only a single switch and an inductor coupled to the quasi‐Z‐source inductor is utilized to reduce the magnetic cores and realize soft switching for all semiconductors without imposing any extra voltage or current stress on the converter elements. The main switch operates at zero voltage switching and zero current switching (ZCS) at turn‐on which is independent of the load and duty cycle variations. Hence, soft switching condition for the main switch at turn‐off is easily provided by a snubber capacitor. In addition, the reverse recovery problem of all the converter diodes is significantly mitigated by ZCS at turn‐off while the continuous current at the input source is maintained. In order to verify the theoretical analysis and the proposed converter operation, a converter prototype is implemented at 300 W and 100 kHz. Finally, a comprehensive comparison is performed between the proposed converter and other high step‐up converters based on quasi‐Z‐source structure, to demonstrate the merits of the proposed converter. [ABSTRACT FROM AUTHOR]

Abstract This article suggests a non‐isolated high step‐up interleaved DC–DC topology for renewable energy applications. Two three‐winding coupled‐inductors along with two voltage multiplier cells are used to enhance the voltage gain significantly. One interesting aspect of this new topology is that high duty cycles are not required to achieve high voltage gains; this is done by adjusting the turn ratio of the coupled inductors. Moreover, the presented interleaved converter enjoys not only having less current stress due to the interleaving structure, but also showing 16% increase in voltage gain compared to the best similar boost topologies. Additional elements are designed for the purpose of soft switching and gain increase, which have little effect on the cost, weight and size of the proposed converter. Interestingly, the voltage stresses both on the switching devices and passive elements are much less than the output voltage. Furthermore, the coupled inductor's leakage inductance energy is recovered by employing a passive clamp circuit to minimize stresses across the semiconductors; therefore, efficiency is improved. The suggested converter is analyzed in the steady state, and a 400 W experimental setup was implemented; the outcomes verify the practicality of the proposed boost converter in accordance with the analysis.

An ultra‐low quiescent current tri‐mode DC–DC boost converter is proposed in this paper, which can efficiently handle loads from 1 μA to 300 mA, providing 5‐V output from 3 to 4.2‐V input. Hysteresis current mode control is adopted to realize seamless mode switching between continuous conduction mode (CCM) and discontinuous conduction mode (DCM). In order to deal with the light load situation, this paper proposes a quasi burst mode (QBM). In this mode, most of the modules are turned off and only the QBM controller, low‐power current bias and sample and hold circuit are retained, which significantly reduces the static current of the converter, and thus improves the light load efficiency. Meanwhile, the average current of error amplifier and comparator are reduced significantly by dynamic biasing. Finally, the efficiency of the converter is greatly improved and kept at a reasonable output ripple. The proposed converter is implemented in a 0.13‐μm BCD process design and manufacturing. The test results show that the quiescent current of the converter is only 780 nA, which can achieve a peak efficiency of 95.6%, and ensure that the efficiency is maintained above 80% in the load range of 10 μA to 300 mA. [ABSTRACT FROM AUTHOR]

A fully soft switched high step‐up/down bidirectional converter is presented in this paper. The high voltage conversion ratio is achieved by a pair of coupled inductors along with a switched capacitor while all active switches operate at zero voltage switching. To provide soft switching condition for the main switches and absorb the leakage inductance energy of coupled inductors, active clamp circuits are utilized for both operating modes. Furthermore, all active switches body diodes which are utilized as converter diodes turn off at zero current switching (ZCS) and thus, the reverse recovery problem is eradicated. Additionally, the voltage stress of the main switches is reduced in comparison with the basic bidirectional buck/boost converter and thus, their drain‐source resistance is relatively lower which leads to considerably lower conduction loss. All the mentioned advantages along with relatively low number of components contribute to the converter efficiency. Theoretical analysis of the proposed converter is presented in detail for both operating modes and the experimental results from the implementation of a 300 W prototype circuit confirm the validity of the converter performance. A comprehensive comparison table between the proposed converter and the recent counterpart bidirectional converters is presented to demonstrate the converter advantages. [ABSTRACT FROM AUTHOR]

This article suggests a non‐isolated high step‐up interleaved DC–DC topology for renewable energy applications. Two three‐winding coupled‐inductors along with two voltage multiplier cells are used to enhance the voltage gain significantly. One interesting aspect of this new topology is that high duty cycles are not required to achieve high voltage gains; this is done by adjusting the turn ratio of the coupled inductors. Moreover, the presented interleaved converter enjoys not only having less current stress due to the interleaving structure, but also showing 16% increase in voltage gain compared to the best similar boost topologies. Additional elements are designed for the purpose of soft switching and gain increase, which have little effect on the cost, weight and size of the proposed converter. Interestingly, the voltage stresses both on the switching devices and passive elements are much less than the output voltage. Furthermore, the coupled inductor's leakage inductance energy is recovered by employing a passive clamp circuit to minimize stresses across the semiconductors; therefore, efficiency is improved. The suggested converter is analyzed in the steady state, and a 400 W experimental setup was implemented; the outcomes verify the practicality of the proposed boost converter in accordance with the analysis. [ABSTRACT FROM AUTHOR]

The fault detection issue is investigated for complex stochastic delayed systems in the presence of positivity constraints and semi-Markov switching parameters. By choosing a mode-dependent fault detection filter (FDF) as a residual generator, the corresponding fault detection is formulated as a positive $\mathscr {L}_{1}$ filter problem. Attention is focused on the design of a mode-dependent FDF to minimize the error between the residual signal and the fault signal. The designed FDF features good sensitivity of the faults and robustness against the external disturbances. Subsequently, by means of the linear copositive Lyapunov functional (LCLF), stochastic stability is proposed to satisfy an expected $\mathscr {L}_{1}$ -gain performance. Some solvability conditions for the desired mode-dependent FDF are established with the help of a linear programming approach. Finally, an application example of a data communication network model is provided to demonstrate the effectiveness of the theoretical findings. [ABSTRACT FROM AUTHOR]

This brief is devoted to protocol-based control method design for semi-Markov switching systems with dynamic quantization. Essential different from the semi-Markov process with arbitrary switchings, by proposing a novel semi-Markov process subjected to a deterministic switching signal, a generalized framework of semi-Markov switching systems is set up. With respect to the quantization range of the dynamic quantizer, an improved event-triggered protocol associated with the quantizer parameter is proposed. On account of mode-dependent Lyapunov theory, sufficient conditions are established to ensure the stochastic finite-time boundedness of the resulting system. In the end, a tunnel diode circuit model shows the practicability and effectiveness of the presented method. [ABSTRACT FROM AUTHOR]

This article is concerned with the issue of quantized sliding-mode control (SMC) design methodology for nonlinear stochastic switching systems subject to semi-Markovian switching parameters, T–S fuzzy strategy, uncertainty, signal quantization, and nonlinearity. Compared with the previous literature, the quantized control input is first considered in studying T–S fuzzy stochastic switching systems with a semi-Markovian process. A mode-independent sliding surface is adopted to avoid the potential repetitive jumping effects. Then, by means of the Lyapunov function, stochastic stability criteria are proposed to be dependent of sojourn time for the corresponding sliding-mode dynamics. Furthermore, the fuzzy-model-based SMC law is proposed to ensure the finite-time reachability of the sliding-mode dynamics. Finally, an application example of a modified series dc motor model is provided to demonstrate the effectiveness of the theoretical findings. [ABSTRACT FROM AUTHOR]

In this article, we demonstrate a new strategy for achieving a kind of shape-controlled tunable microwave absorbers based on shape memory polymers (SMPs). Using the heat-driven shape memory effect of SMPs, a frequency-tunable absorber and a magnitude-tunable absorber are designed. Both of the designs consist of a periodic metallic array printed on both sides of the FR4 substrate, SMPs’ substrate (VeroWhitePlus) in the middle layer, and a metallic ground at the bottom. The equivalent circuit models are introduced to analyze the operational principles of the two absorbers. Furthermore, the functionalities of the designed shape-controlled tunable absorbers are investigated by full-wave simulations. For the frequency-tunable absorber design, the simulated results indicate that the resonant frequency can be tuned from 11.3 to 13.5 GHz with a frequency shift of 2.2 GHz. For the other design, the simulated results show that the reflection coefficient can be tuned from −17.00 to −1.34 dB. The proposed frequency shift responses and magnitude modulation responses are experimentally demonstrated by fabricating two prototypes containing 33 $\times33$ units. The above designs overcome the limitation of the traditional electrically adjustable wave absorber requiring an external power supply, providing a new paradigm for the design of tunable devices. [ABSTRACT FROM AUTHOR]

This article is to predict and cancel differential-mode (DM) noise for high-power thyristor (HPT) trigger circuits and improve the reliability of capacitive pulsed power supply (CPPS). A lumped model of HPT trigger circuit is developed for the DM noise prediction within a concerning frequency range. The generation mechanism and propagation path of the DM noise are systematically studied. To attenuate the DM noise, a DM filter is proposed and discussed. The component parameters of the filter are investigated to improve its DM noise suppression effect. The DM spectrum for the HPT trigger circuit and the insertion losses of the DM filter are simulated and analyzed. Ultimately, DM spectrum tests are carried out. Both the simulated and measured results validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

This article investigates the input–output finite-time stability (IO-FTS) for nonlinear hidden semi-Markov switching systems (S-MSSs) via the asynchronous sliding mode control (SMC) approach. Under the assumption that a detector is set up to estimate the mode value, the mode of the original system is not directly accessible. The asynchrony between the system and controller is described as a hidden semi-Markov model (HSMM). Many practical factors, such as semi-Markov switching parameters, finite-time interval, asynchronous phenomenon, uncertain parameters, and nonlinearity, are taking into account during the SMC design process. We aim to design an efficient finite-time asynchronous SMC scheme under a hidden semi-Markov switching effect. A novel sliding switching surface (SSS) is constructed, in which the SMC law rises asynchronously with original S-MSSs. Then, by means of finite-time stability, an asynchronous SMC law is synthesized to guarantee that the associated hidden S-MSSs fulfill the reaching condition within a finite time. Furthermore, sufficient conditions are derived in view of the IO-FTS of sliding mode dynamics under the framework of a novel inequality lemma. Results are given for the application of this control design method to a single-link robot arm model (SLRAM). [ABSTRACT FROM AUTHOR]

The emerging 4D printing techniques open new horizons for fabricating self-actuated deformable objects by combing strength of 3D printing and stimuli-responsive shape memory materials. This article focuses on designing self-actuated deformable solids for 4D printing such that a solid can be programmed into a temporary shape and later recovers to its original shape after heating. To avoid a high material cost, we choose a dual-material strategy that mixes an expensive thermo-responsive shape memory polymer (SMP) material with a common elastic material, which however leads to undesired deformation at the shape programming stage. We model this shape programming process as two elastic models with different parameters linked by a median shape based on customizing a constitutive model of thermo-responsive SMPs. Taking this material modeling as a foundation, we formulate our design problem as a nonconvex optimization to find the distribution of SMP materials over the whole object as well as the median shape, and develop an efficient and parallelizable method to solve it. We show that our proposed approach is able to design self-actuated deformable objects that cannot be achieved by state of the art approaches, and demonstrate their usefulness with three example applications. [ABSTRACT FROM AUTHOR]

The purpose of web service composition is to satisfy complex requirements by constructing a composite service through loosely coupling web services over the Internet. Services available for composition may experience changes in performance and reliability at any time. Therefore, it is desirable to estimate performance and reliability of the composite service based on the data of atomic services such that it is checked up before service deployment whether the service-level agreement is satisfied. In this article, a phase-type expansion approach to establish an expanded homogeneous continuous time Markov chain of composite web services is proposed. By explicitly including failure states and restart states into the model, both performance and reliability can be computed for the composite service via phase-type fitting method based on the observations on execution times of atomic services. Experimental results based on real-world web services are provided to demonstrate the efficacy of the proposed approach. [ABSTRACT FROM AUTHOR]

Constrained motion planning is a challenging field of research, aiming for computationally efficient methods that can find a collision-free path on the constraint manifolds between a given start and goal configuration. These planning problems come up surprisingly frequently, such as in robot manipulation for performing daily life assistive tasks. However, few solutions to constrained motion planning are available, and those that exist struggle with high computational time complexity in finding a path solution on the manifolds. To address this challenge, we present Constrained Motion Planning Networks X (CoMPNetX). It is a neural planning approach, comprising a conditional deep neural generator and discriminator with neural gradients-based fast projection operator. We also introduce neural task and scene representations conditioned on which the CoMPNetX generates implicit manifold configurations to turbo-charge any underlying classical planner such as sampling-based motion planning methods for quickly solving complex constrained planning tasks. We show that our method finds path solutions with high success rates and lower computation times than state-of-the-art traditional path-finding tools on various challenging scenarios. [ABSTRACT FROM AUTHOR]

In this article, the issue of positive $\mathcal {L}_{1}$ filter design is investigated for positive nonlinear stochastic switching systems subject to the phase-type semi-Markov jump process. Many complicated factors, such as semi-Markov jump parameters, positivity, T–S fuzzy strategy, and external disturbance, are taken into consideration. Practical systems under positivity constraint conditions and unpredictable structural changes are characterized by positive semi-Markov jump systems (S-MJSs). First, by the key properties of the supplementary variable and the plant transformation technique, phase-type S-MJSs are transformed into Markov jump systems (MJSs), which means that, to an extent, these two kinds of stochastic switching systems are mutually represented. Second, with the help of the normalized membership function, the associated nonlinear MJSs are transformed into the local linear MJSs with specific T–S fuzzy rules. Third, by choosing the linear copositive Lyapunov function (LCLF), stochastic stability (SSY) criteria are given for the corresponding system with $\mathcal {L}_{1}$ performance. Some solvability conditions for positive $\mathcal {L}_{1}$ filter are constructed under a linear programming framework. Finally, an epidemiological model illustrates the effectiveness of the theoretical findings. [ABSTRACT FROM AUTHOR]

In this article, a novel single-switch, high step-up dc–dc converter based on three-winding coupled inductor and voltage multiplier circuit (VMC) is proposed. And on this basis, pump capacitor unit (PCU) is integrated to achieve a very high voltage gain. The converter makes full use of the advantages of three-winding coupled inductor, skillfully combines it with the VMC, and integrates the PCU that can be used in superposition to further improve the voltage gain. The voltage stress of the switch is reduced by using a passive clamping circuit to recycle the leakage energy of the coupled inductor. The operating principle and steady-state analysis of the presented converter in continuous conduction mode are introduced in detail. Moreover, the comparative analysis shows that under the same conditions, the proposed converter has higher voltage gain and lower voltage stress than others. Several advantages include high voltage gain, low voltage stress, low turns ratio of coupled inductor, and high conversion efficiency, make the proposed converter very suitable for new energy generation applications, such as photovoltaic systems. Finally, the feasibility of the proposed converter and the correctness of theoretical analysis are verified by a 500-W prototype at 50 kHz switching frequency. [ABSTRACT FROM AUTHOR]

The issue of sliding-mode control (SMC) design is studied for a class of nonlinear semi-Markovian switching systems (S-MSSs) via T–S fuzzy approach. Compared with previous literature, novel integral sliding-mode surfaces (ISMSs) are developed to depend on the designed controller gains and projection matrices. The aim of this work is to design an appropriate fuzzy SMC law under complex stochastic semi-Markovian switching process. For this purpose, the novel ISMSs are developed under the T–S fuzzy modeling framework. Then, based on the weak infinitesimal operator theory, sufficient conditions are given for stochastic stability criteria relying on the sojourn-time. Furthermore, an appropriate fuzzy SMC law is proposed to drive the state signals onto the predefined fuzzy manifold. Finally, an electric circuit model illustrates the effectiveness of the theoretical findings. [ABSTRACT FROM AUTHOR]

This article presents an LED driver for lighting and visible light communication (VLC), which utilizes the light of the LEDs to wirelessly transmit data by modulating their instantaneous current. The solution proposed in this article seeks to unite the high efficiency of switched-mode power supplies with the wide bandwidth of linear power amplifiers (LPAs) to achieve high-speed communications. The hybrid converter processes the energy from a 48-V dc bus with an efficiency of 94% while supplying a 20-W LED load, and providing 3.68 MHz of bandwidth for VLC. Details regarding frequency limitations are provided in terms of a Laplace model. The impact of the LPA on the overall efficiency is mitigated by adopting specific design constraints. Finally, experimental results are shown from a prototype working with signals aimed at multicarrier multilevel modulations based on orthogonal frequency division multiplexing. [ABSTRACT FROM AUTHOR]

This letter presents a millimeter-wave (mmWave) tri-modal patch antenna with a size of $0.46\,\lambda _{0}\times 0.46\,\lambda _{0}\times 0.11\,\lambda _{0}$ , in which $\lambda _{0}$ is the wavelength in air at the center frequency. It is the first example of a tri-modal patch antenna in the mmWave frequency range. Compared to previous sub-6 GHz tri-modal patches, special approaches to handle the three port excitation at mmWave are required. The radiation performance with various feeding structures, fabrication approaches, and the challenges of designing tri-modal patch antennas in mmWave bands are detailed. The advantage of utilizing the tri-modal patch concept is that with proper excitation, a compact three-port antenna can be designed to exhibit broadside radiation and low mutual coupling within a single element. Experimental results demonstrate a three-port antenna operating at 26 GHz with an impedance bandwidth and realized gain of 5.4% and 5.0 dBi, respectively, which is suitable for use as a unit cell in mmWave massive multiple-input--multiple-output (MIMO) antenna applications. [ABSTRACT FROM AUTHOR]

This article presents a new hybrid-mode pulse-frequency-modulation control method for an LLC resonant converter. In the proposed control method, the primary-side resonant current sensing signal of the current-mode control variable is combined with a ramp signal of the voltage-mode control variable to determine an operating frequency. Then, the proposed control method mainly modulates the ramp signal in accordance with the output load condition. Therefore, the control-to-output voltage transfer function has both the current-mode control and voltage-mode control characteristics that provide fast frequency response and stable output voltage regulation in a light-load condition. In addition, since the ramp signal is also used for slope compensation of the resonant current sensing signal, an external slope compensation circuit is not required. A small-signal ac modeling and loop analysis of the proposed method verify the advantages. The proposed control method is implemented into a field programmable gate array (FPGA) board with an analog front-end board. An experiment is carried out on a 288-W LLC resonant converter. The result shows that the proposed control method provides fast dynamic performance and stable operation under a light-load condition without an additional slope compensation circuit. [ABSTRACT FROM AUTHOR]

This brief investigates the sliding mode control (SMC) for semi-Markov jump cyber-physical systems (S-MJCPSs) under randomly occurring deception attacks (RODA). It is assumed that the adversaries inject false data into the control signal in probability. First, a mode-dependent sliding surface is designed under the framework of integral form. Second, the criteria to ensure stochastic stability (SS) of the corresponding system are proposed, which establishes the theoretical framework of semi-Markov Lyapunov function. Third, an appropriate SMC law under attacks and uncertainties is constructed to drive the states of S-MJCPSs onto the switching manifold in finite time. Finally, the simulation study on a single-link robot arm model (SLRAM) is provided to demonstrate the obtained results. [ABSTRACT FROM AUTHOR]

Four-dimensional printing (4DP) is a newly emerged technology that uses smart materials for additive manufacturing and thus enables shape and/or property change upon stimulus after the printing process. Present study on 4DP has been focused on open-loop stimulus, which can hardly ensure high shape precision and predictable final states. In this article, a new closed-loop 4DP (CL4DP) process supplementing 4D printed actuation with closed loop control methods is proposed. Image feedback is used for enhancing the conventional open loop 4DP morphing process and a controller is implemented to regulate the intensity of the stimulus accordingly in real-time. To achieve precise control, a nonlinear affine system model is built by model identification with measurement data to describe the dynamic shape recovery process of the 4D-printed shape memory polymer (SMP). Precise shape control is achieved and the effects of controller parameters on the precision of CL4DP are studied. Traditionally, SMP has a discrete number of selected steady states. With CL4DP, such steady states can be continuous and arbitrary. [ABSTRACT FROM AUTHOR]

This article proposes a winding condition monitoring scheme for inverter-fed permanent magnet synchronous machine (PMSM) based on high frequency (HF) current injection. By setting specific current references for the HF positive and negative sequence current regulators, HF current can be injected into different phase winding pairs, and then the HF line voltage deviations are extracted for winding condition monitoring. The amplitude of the extracted HF line voltage deviation is defined as the condition indicator to evaluate the condition of phase winding. In the proposed method, the conditions of all phase windings can be separately monitored, where not only inter-turn short-circuit fault (ISF) in one phase but also ISFs in multiple phases can be accurately identified. Simulations and experiments have been carried out to validate the proposed method. It shows that the proposed method has high sensitivity to ISF and negligible sensitivity to the operation conditions of the PMSM. [ABSTRACT FROM AUTHOR]

A relational bipartite communication problem is presented that has an efficient quantum simultaneous-messages protocol, but no efficient classical two-way protocol. [ABSTRACT FROM AUTHOR]

In this brief, we provide three operational boundaries in closed analytical form for a Constant ON-Time buck converter working in continuous current mode. Two of these boundaries are related to the sudden appearance of pulse-bursting induced by either (i) the hysteresis of the comparator that drives the input of the block implementing the circuit control algorithm (hysteresis condition), or (ii) by a period doubling bifurcation (bouncing condition). The third operational boundary corresponds to the saturation condition of the circuit controller which does no longer guarantee an OFF-time larger than the minimum allowed one. These stability boundaries are provided both for the adaptive and the fixed ON-time working modes. [ABSTRACT FROM AUTHOR]

Minimally invasive implantation of subdural electrodes can dramatically benefit the patients with various neurological diseases. In modern clinical practice, the implantation procedure of the electrode arrays remains traumatic for patients and increases postoperative infection risk. Here we report a design and insertion technique of thermally activated shape-memory polymer-based electrode array that can recover up to ten times length deformation. The compressed four-centimeter wide array can be easily packed into a three-millimeter diameter tube and subsequently deployed thought five-millimeter opening in a restricted space between a brain phantom and a simulated skull. The mechanical properties of the developed array are comparable to the materials traditionally employed for the purpose, and the electrical and signal recording properties are preserved after shape deformation and recovery. Additionally, the array is biocompatible and exhibits conformability to a curvy brain surface. The results demonstrate that insertion of the electrode array through a small hole into a restricted space similar to subdural cavity is possible, which may inspire future solution of minimal invasive implantation for patients suffering from epilepsy, amyotrophic lateral sclerosis or tetraplegia. [ABSTRACT FROM AUTHOR]

The industrial internet of things (IIoT) is emerging as a global trend to dramatically enhance the intelligence and efficiency of the industries in recent years. With the emphasis on data communication by IIoT, cyber vulnerabilities are introduced at the same time. As a key subsystem of the industrial automation systems, the supervisory control and data acquisition (SCADA) system is becoming one of the primary targets for cyberattacks in the IIoT paradigm. In this paper, the semi-Markov process (SMP) is employed to model and evaluate the cyberattacks against the SCADA systems considering the insider assistance. Based on the SMP model, the probability distribution of the time-to-compromise the system of the attacks is derived with the Monte Carlo simulation (MCS). Then, a FlipIt game model is developed to investigate the defense and attack strategies of the defender and attacker, and analyze the impacts of the insider assistance. Case studies were carried out to verify the proposed model. The results of the case studies show that the insider assistance will improve the payoff of the attacker and increase the defense action frequency of the system defender. With a high enough defense action frequency, the defender can force the attacker to drop out and eliminate the attack actions. [ABSTRACT FROM AUTHOR]

This brief proposes a high-speed and power-efficient multi-bit cyclic analog-to-digital converter (MC ADC) for CMOS image sensor applications. The proposed 13-bit MC ADC, which uses a 4-bit single-slope (SS) quantizer as a sub-ADC, resolves the sampled input voltage, followed by the cyclic SS quantization operation that repeatedly produces and quantizes the residue voltage. It operates in only seven phases to resolve 13-bit, thus achieving high conversion speed. Moreover, the 4-bit SS quantizer employs a simple and power-efficient structure that includes only the analog circuits of an operational amplifier and a comparator. A test chip with the proposed MC ADC was fabricated using a 0.18- $\mu \text{m}$ standard CMOS process technology. The measurement results show that the proposed MC ADC achieves a differential nonlinearity of +0.5/−0.54 LSB and an integral nonlinearity of +1.7/−2.8 LSB. In addition, the maximum signal-to-noise- and-distortion ratio and the effective number of bits are measured to be 73.14 dB and 11.86-bit, respectively. The measured power consumption per channel is only 87 $\mu \text{W}$ at a sampling frequency of 781 kHz. Moreover, the figure of merit (FoM), which includes the power consumption per channel, row line time, and ADC resolution, is only 13.6 fJ/conversion, achieving the best FoM among the compared works. Therefore, the proposed MC ADC is suitable for CMOS image sensor applications requiring high conversion speed and low power consumption, such as digital single-lens reflex cameras and ultra-high-definition television broadcast cameras. [ABSTRACT FROM AUTHOR]

Water treatment is the most concerned research area as it is closely related to the quality of human life. Capacitive de-ionization (CDI) has become a popular desalination technique for water treatment in recent years; however, transferring CDI technology to practice industrial applications face many problems due to the lack of experience and ability of monitoring on its operation status. Thus, in this article, a novel self-powered smart monitoring platform (SMP) is codesigned with a laboratory-scale CDI cell by providing regulated polarized voltage to prevent faradaic reactions and to evaluate CDI's performance using desalination metrics. The proof-of-concept SMP can acquire sensory data and wirelessly transmit information to the reader by radio-frequency identification (RFID) technique. A laboratory-scale CDI cell is fabricated in house by the cost-effective carbon electrodes with high electrochemical stability. Experiments are conducted to evaluate the function of the system on real-time monitoring of the CDI cell for their conductivity, salt absorption, and charge efficiency. The measurement results demonstrate that the proposed prototype is effective in terms of supplying, monitoring, and diagnosing the operation condition of the CDI cell. Furthermore, the proof-of-concept SMP developed for the CDI reactor can achieve up to 8.8-m communication distance, while consuming 402.6 μW active power during operation. Therefore, it is a suitable choice for low-power and low-cost wireless sensor network. [ABSTRACT FROM AUTHOR]

This paper concerns a positive $\mathcal {L}_{1}$ observer for positive nonlinear semi-Markovian switching systems (MSSs) via the expansion of Taylor formula and the fuzzy Lyapunov function approach, in which semi-Markovian switching parameters, positivity, Takagi–Sugeno (T–S) fuzzy, and external disturbance are all considered in a unified framework. A fuzzy Lyapunov function approach with less conservativeness is introduced into the research of positive systems. In the system under consideration, positive S-MSSs with the semi-Markovian process can describe more complex systems in a practical control process. The main motivation of this paper is that the practical system subject to positivity and abrupt changes can be described by positive nonlinear S-MSSs, which always needs to consider the external disturbance. First, by using the normalized membership function approach, positive nonlinear S-MSSs can be represented by local positive T–S fuzzy S-MSSs. Second, by constructing the fuzzy Lyapunov function, some sufficient conditions are proposed for stochastic stability and $\mathcal {L}_{1}$ -gain performance analysis, respectively. Then, a positive $\mathcal {L}_{1}$ observer in a novel standard linear programming condition is designed to guarantee the resulting closed–loop augmented system is positive and stochastically stable with a required $\mathcal {L}_{1}$ -gain performance. Finally, a practical example about the epidemiological model is introduced to show the effectiveness of the main theory. [ABSTRACT FROM AUTHOR]

Recent advances of energy management system in a smart home can lead to load monitoring of electrical appliances for energy saving and reduction of electricity bill. Thus, smart metering technology is getting widely implemented in several electricity distribution networks. Most of the existing research are concentrated towards individual power consumption of different household loads using some machine learning algorithm, which can increase computational burden of the processor. In this article, an improved method for estimation of the individual appliance current is carried out from a group of connected consumer electronics loads. The proposed method consists of two steps, first is to collect and store the current data of individual appliances with varying load for on line application. The second step is to estimate the individual load current using the stored data. In the proposed method, a search-based optimization, i.e., Artificial Bee Colony (ABC) algorithm is used for the estimation of individual electrical load. Suitable simulations and experimental studies are carried out on a practical household system to demonstrate the suitability of the proposed methodology. [ABSTRACT FROM AUTHOR]

The offline Switched Mode Power Supply (SMPS) draw non‐sinusoidal line current from the utility power supply, thereby introducing unwanted harmonics and also generate significant electromagnetic interference (EMI). Power factor correction (PFC) converters can be used to improve the power factor. But they also generate EMI in both Differential Mode (DM) and Common Mode (CM). In this paper, the EMI generated by the flyback PFC converter is addressed. A lumped circuit model for CM conducted EMI generated in a flyback converter, including the HF transformer's parasitics and the components, is considered. The parasitics of the HF transformer are calculated and measured experimentally. Using them, the resonant frequencies of the flyback converter are calculated for validation. A technique for determining the required balancing capacitor to mitigate CM conducted EMI is presented. A novel technique by splitting this balancing capacitor with their mid‐point grounded for further reduction of this EMI is presented. This technique can eliminate the Cy capacitors of the EMI line filter connected between line/neutral to the ground. Hence for the same amount of CM conducted EMI mitigation, the size and the cost of EMI line filters are reduced. Theoretical analysis, simulation results, and experimental verifications are presented. [ABSTRACT FROM AUTHOR]

It is well known that noise source impedance plays a significant role in designing conducted electromagnetic interference (EMI) filters. However, the noise source impedance in a switched‐mode power supply is not easy to extract. In this study, the noise source impedance in a single‐phase inverter is extracted under operating conditions based on a two‐probe approach. First, the noise source modelling and analysis are implemented for the inverter system to illustrate the importance of impedance. Furthermore, the proposed two‐probe method is introduced and then validated by several passive components. Proper and straightforward premeasurement calibrations are needed to eliminate the influence of the probes and cables. The approach can accurately extract the common‐mode and differential‐mode noise source impedances with different configurations according to the characteristics of their propagation paths. Compared with a traditional EMI filter design, the experimental results show that the one designed by the proposed approach can effectively attenuate the conducted EMI noises to meet the requirements with more appropriate and optimised parameters. [ABSTRACT FROM AUTHOR]

Power electronic converters are increasingly used in power systems. However, they are vulnerable components and prone to aging failures, thus affecting overall system reliability. Therefore, their availability modeling especially in large-scale power electronic-based power systems is of paramount importance. This letter introduces four different approaches for converter availability modeling considering aging failures under different maintenance strategies. The accuracy and calculation burden of these approaches are illustrated by numerical analysis. It is shown that the method of device of stages and piece-wise approach are the most applicable methods in the case of corrective and preventive maintenance strategies respectively. [ABSTRACT FROM AUTHOR]

This paper presents an adaptive fixed-time convergent continuous controller designed to solve a stock management problem with the objective to drive stock and supply chain levels at the reference values, subject to loss rate disturbances whose bounds are unknown. The only measurable state of the supply chain is the inventory retailer stock level, whereas the supply line inventory level should be estimated. The designed controller includes a fixed-time convergent differentiator, an adaptive fixed-time convergent disturbance observer, and a fixed-time convergent regulator. The adaptive fixed-time convergent observer is used to estimate a disturbance without excessively increasing the controller gains. The controller design is validated in a case study of stock management. The calculated upper estimate for the total settling (convergence) time and the obtained simulation results confirm the fixed-time convergence and the robustness of the designed controller. [ABSTRACT FROM AUTHOR]

Multiple players are each given one independent sample, about which they can only provide limited information to a central referee. Each player is allowed to describe its observed sample to the referee using a channel from a family of channels $\mathcal {W}$ , which can be instantiated to capture, among others, both the communication- and privacy-constrained settings. The referee uses the players’ messages to solve an inference problem on the unknown distribution that generated the samples. We derive lower bounds for the sample complexity of learning and testing discrete distributions in this information-constrained setting. Underlying our bounds is a characterization of the contraction in chi-square distance between the observed distributions of the samples when information constraints are placed. This contraction is captured in a local neighborhood in terms of chi-square and decoupled chi-square fluctuations of a given channel, two quantities we introduce. The former captures the average distance between distributions of channel output for two product distributions on the input, and the latter for a product distribution and a mixture of product distribution on the input. Our bounds are tight for both public- and private-coin protocols. Interestingly, the sample complexity of testing is order-wise higher when restricted to private-coin protocols. [ABSTRACT FROM AUTHOR]

A central server needs to perform statistical inference based on samples that are distributed over multiple users who can each send a message of limited length to the center. We study problems of distribution learning and identity testing in this distributed inference setting and examine the role of shared randomness as a resource. We propose a general-purpose simulate-and-infer strategy that uses only private-coin communication protocols and is sample-optimal for distribution learning. This general strategy turns out to be sample-optimal even for distribution testing among private-coin protocols. Interestingly, we propose a public-coin protocol that outperforms simulate-and-infer for distribution testing and is, in fact, sample-optimal. Underlying our public-coin protocol is a random hash that when applied to the samples minimally contracts the chi-squared distance of their distribution to the uniform distribution. [ABSTRACT FROM AUTHOR]

Multiple-input multiple-output visible light communications (MIMO-VLC) have been considered as an advanced technique owing to the enhancement of communication capacity and reliability. However, the performance of MIMO-VLC highly depends on channel correlation, which means that the system performs worse when the channels are more highly correlated. Some studies have developed techniques to alleviate channel correlation and improve the performance of spatial multiplexing MIMO-VLC systems. However, these works have not considered situations where all LEDs and PDs are integrated into a compact structure. In this paper, a single-user spatial multiplexing MIMO-VLC system with densely distributed LEDs (light emitting diodes) and PDs (photodiodes) is proposed. Designs of optimal signal vectors and system structures are introduced, to fulfill multiplexing gains when LEDs and PDs are set close to each other respectively. Numerical simulations are carried out and the results illustrate that the proposed system can realize multiplexing gains over the system where LEDs and PDs are distributed densely, and also outperforms the traditional repetition coding (RC) technique. [ABSTRACT FROM AUTHOR]

Dynamic fault tree (DFT) is a top-down deductive technique extended to model systems with complex failure behaviors and interactions. In two last decades, different methods have been applied to improve its capabilities, such as computational complexity reduction, modularization, intricate failure distribution, and reconfiguration. This paper uses semi-Markov process (SMP) theorem for DFT solution with the motivation of obviating the model state-explosion, considering nonexponential failure distribution through a hierarchical solution. In addition, in the proposed method, a universal SMP for static and dynamic gates is introduced, which can generalize dynamic behaviors like functional dependencies, sequences, priorities, and spares in a single model. The efficiency of the method regarding precision and competitiveness with commercial tools, repeated events consideration, computational complexity reduction, nonexponential failure distribution consideration, and repairable events in DFT is studied by a number of examples, and the results are then compared to those of the selected existing methods. [ABSTRACT FROM AUTHOR]

With the increasing application of Information and Communication Technologies (ICTs), cyberattacks have become more prevalent against Cyber-Physical Systems (CPSs) such as the modern power grids. Various methods have been proposed to model the cybersecurity threats, but so far limited studies have been focused on the defensive strategies subject to the limited security budget. In this paper, the power supply reliability is evaluated considering the strategic allocation of defense resources. Specifically, the optimal mixed strategies are formulated by the Stackelberg Security Game (SSG) to allocate the defense resources on multiple targets subject to cyberattacks. The cyberattacks against the intrusion-tolerant Supervisory Control and Data Acquisition (SCADA) system are mathematically modeled by Semi-Markov Process (SMP) kernel. The intrusion tolerance capability of the SCADA system provides buffered residence time before the substation failure to enhance the network robustness against cyberattacks. Case studies of the cyberattack scenarios are carried out to demonstrate the intrusion tolerance capability. Depending on the defense resource allocation scheme, the intrusion-tolerant SCADA system possesses varying degrees of self-healing capability to restore to the good state and prevent the substations from failure. If more defense resources are invested on the substations, the intrusion tolerant capability can be further enhanced for protecting the substations. Finally, the actuarial insurance principle is designed to estimate transmission companies’ individual premiums considering correlated cybersecurity risks. The proposed insurance premium principle is designed to provide incentive for investments on enhancing the intrusion tolerance capability, which is verified by the results of case studies. [ABSTRACT FROM AUTHOR]

Multiple-input multiple-output (MIMO) is a promising technology to efficiently improve the achievable rate of white light-emitting diodes (LEDs) enabled visible light communication (VLC) systems. Nevertheless, for conventional MIMO techniques such as spatial diversity (SD) and spatial multiplexing (SMP), the working mode of each LED transmitter is independent of users’ spatial positions. In this article, we propose and investigate three user-centric MIMO techniques, including SD/SMP switching, adaptive SMP (aSMP), and SD-aided aSMP (SD-aSMP), for achievable rate improvement of indoor MIMO-VLC systems, by exploiting users’ spatial positions as a new degree of diversity. The analytical and simulation results show that the achievable rate of a 4 × 4 MIMO-VLC system in a typical indoor environment can be significantly improved by applying the user-centric MIMO techniques compared with the conventional ones. More specifically, SD/SMP switching can enjoy both high diversity gain of SD and high multiplexing gain of SMP at different signal-to-noise ratio (SNR) regions, while aSMP mitigates the adverse effect of noise amplification in conventional SMP and SD-aSMP can benefit from additional diversity gain. Furthermore, we also show that the proposed user-centric MIMO techniques outperform conventional MIMO techniques under the condition of only slightly increased computational complexity with limited feedback information. [ABSTRACT FROM AUTHOR]