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This study describes a technique for automated and accurate inductance estimation in synchronous DC–DC buck and boost converters. The method of inductor value estimation is based on the dependence of the steady-state output voltage on the inductance value, in the case of a fixed inductor peak current. The measurement algorithm yields effective inductance value, and is aimed to be executed once during the start-up procedure under light load current condition. As the measurement is performed during the start-up sequence with low-load current, a dedicated current sensor with high accuracy can be employed, allowing to target high measurement accuracy in the range of ±5%. The presented technique is developed to enable the automated design of a digital controller for general purpose DC–DC converter but can be used in different applications such as analogue feedback-loop adjustment or improving the digital current estimator accuracy. [ABSTRACT FROM AUTHOR]

On the basis of serious electromagnetic interference (EMI) produced by power electronic equipment, parasitic capacitance existing between transistor and heat sink is considered as the main factor disturbing common-mode loop. Calculation model of parasitic capacitance is established by using finite element method and electrostatic field principle, and computing method is also derived. EMI improvement method for converter system is proposed by controlling the parasitic capacitance impedance. Experimental results show that changing the permittivity and thickness of the thermal conductive adhesive which are filled between the transistor heat-conducting plate and heat sink to can reduce the conducted interference. [ABSTRACT FROM AUTHOR]

The measurement of modal impedances of switching-mode power supplies (SMPSs) is of paramount importance in electromagnetic compatibility applications, especially when designing electromagnetic interference filters to suppress the conducted and radiated electromagnetic emissions is the target. A novel measurement technique that makes use of an impedance analyzer and a coupling transformer and allows extracting the complex value of common- and differential-mode noise source impedance of an SMPS is proposed. The measurement procedure is first studied from the theoretical point of view, then experimentally validated with passive components, and eventually implemented in a CISPR-25 conducted emission test setup to measure the magnitude and phase of modal impedances of an automotive SMPS under different operation conditions. [ABSTRACT FROM AUTHOR]

The symmetrical monopolar configuration is the prevailing scheme configuration for high voltage direct current (HVDC) interconnectors utilizing the modular multilevel converter (MMC) topology. However, the rigid bipolar configuration is gaining significance, as first projects are currently in planning stage. The purpose of this paper is to analyse both HVDC scheme configurations with regard to cable voltage stresses originating from short-circuit faults. The study focuses on HVDC cables with extruded insulation connected to MMCs equipped with half-bridge (HB) submodules. Basic design aspects in rigid bipolar configuration such as the station grounding concept are discussed. Moreover, various station internal as well as dc faults are examined by means of electromagnetic transient (EMT) simulations. Occurring cable voltage stresses are analyzed with respect to voltage polarity, peak value and wave front-parameters and compared in symmetrical monopolar and rigid bipolar configuration. It is demonstrated that cable overvoltages with same polarity as the dc operating voltage are significantly reduced in schemes operating in rigid bipolar configuration. Voltage reversals caused by the discharge process during a cable fault are nearly independent of the selected scheme configuration. Obtained results are relevant with regard to upcoming projects in rigid bipolar configuration and provide insights to further refine insulation co-ordination aspects related to dc cable systems. [ABSTRACT FROM AUTHOR]

This article addresses the issue of asynchronous partially mode-dependent filtering for networked Markov switching repeated scalar nonlinear systems (MSRSNSs) subject to quantized measurements (QMs). Especially, a novel partially mode-dependent filter (PMDF) is constructed, where the signal transmission of a filter mode occurred randomly and is modeled by a Bernoulli distributed sequence. The designed PMDF is different from state mode, which is governed by an asynchronous switching rule. By utilizing a diagonally dominant-type Lyapunov functional (DDTLF), sufficient conditions ensure that the existence of the PMDF and the $l_{2}-l_{\infty }$ performance index are derived. Finally, an economic example is adopted to substantiate the applicability of the developed theoretical results. [ABSTRACT FROM AUTHOR]

This letter presents a multi-objective probabilistic model for the optimal selection of pilot buses in secondary voltage regulation (SVR) of transmission grids. The pilot-bus selection (PS) problem is formulated in the form of a stochastic multi-objective optimization problem (SMOP). The resultant SMOP is solved toward the non-dominated sorting genetic algorithm (NSGA-II) together with a fuzzy set theory. The applicability of the proposed PS model is examined on a classical test system as well as a practical transmission grid. [ABSTRACT FROM AUTHOR]

Microgrid islanding can improve the reliability of distribution networks by enabling load to be supplied even after a fault has occured nearby. The generation and load devices in microgrids are commonly interfaced by power electronics, causing a lack of inertia in the network. When microgrids transition from grid-connected to islanded operation after a fault, fast dynamics occur which have to be evaluated to assess stability during and after the transition. Their stability can be evaluated by time-domain simulations, however detailed and validated models of power electronic loads and distributed energy resources are required. This paper proposes component-based models of different types of power electronic loads, and single and three phase distributed energy resources. The models are validated with a variety of voltage and frequency transient experiments. A case study is performed where a modified version of the Cigre European LV residential network is islanded after a fault occurs. The results of the proposed, constant impedance and exponential load models are compared. The results indicate that the proposed models should be used for accurate analysis of the voltage and frequency stability during microgrid islanding simulations. [ABSTRACT FROM AUTHOR]

In order to understand how geometric errors propagate and how deviations accumulate in a six-axis motion platform (SMP), a new geometric error model based on the stream of variation (SOV) theory is presented in this paper. SOV theory is widely used in industrial engineering with several steps or phases. The conventional geometric error model only calculates the initial and final orientation, yet the deviations after each step in the whole process are still unknown, which are critical parameters in measuring the product quality. In this new error modeling method, each step in the alignment and welding process in SMP can be considered as a station. Thus, the deviations can also be derived after each station, which is beneficial for error identification. Based on the new error modeling approach involving SOV theory, the validation of an optimized configuration is developed by a series of calculations results. By observing the deviations after each station, the optimized configuration can improve accuracy and reduce power loss compared to a traditional configuration. The new error modeling approach based on SOV theory is systematic and comprehensive, and can be applied in other similar environments. [ABSTRACT FROM AUTHOR]

The use of photovoltaic (PV) systems as the energy source of electrical distributed generators (DG) is gaining popularity, due to the progress of power electronics devices and technologies. Large-scale solar PV power plants are becoming the preferable solution to meet the fast growth of electrical energy demand, as they can be installed in less than one year, as compared to around four years in the case of conventional power plants. Modular multilevel inverters (MMIs) are the best solution to connect these large-scale PV plants to the medium-voltage (MV) grid, due to their numerous merits, such as providing better power quality, having higher efficiency, providing better reliability, and their scalability. However, MMIs are still progressing and need some improvement before they can be implemented safely in the industrial, medium, and high voltage networks. The main purpose of this paper is to review the present MMIs topologies when used in PV applications. The review aims to present a comprehensive study of the various recent submodule circuits associated with MMI topologies. Maximum power point tracking (MPPT) control schemes for PV inverters will be explored extensively. Then, the different control strategies of PV MMIs will be presented and compared to give a holistic overview of the submodules balancing techniques, ranges, and capabilities under balanced and unbalanced grid conditions. In addition, the paper will discuss the future of PV MMIs systems in electricity networks.

A switch-mode power amplifier topology that can achieve both a high conversion efficiency and low-output signal distortion is introduced. Such systems are desirable for ultra-high precision amplifiers that, for example, drive actuators in nanometre-accuracy mechatronic positioning applications in integrated semiconductor manufacturing. An efficient Class-D power stage, which is limited in output signal quality due to its inherent half-bridge interlock time, is combined through a magnetically coupled inductor with a dual buck conversion stage that does not require interlock time and, due to its circulating bias current that defines the half-bridge switching waveforms, achieves very low-harmonic output signal distortion. The control system can seamlessly adjust the current sharing of the two converter stages such that overall conversion efficiencies over 95% and output total harmonic distortion values below −100 dB are achievable at power levels up to several kilowatts. Detailed computer simulations demonstrate the feasibility of the concept.

Here, the setup of a three-phase 100 A linear amplifier is proposed. This work focusses on the use of this linear amplifier as power element for machine-emulation. In contrast to common power electronics, a linear amplifier avoids ripple content in the output current caused by switched-mode operation.

A current-mode buck regulator with delay-based hysteretic control for microcontroller applications is proposed. Unlike conventional hysteretic buck regulators with accurate explicit hysteretic bands, the proposed design relies only on the inherent delay of a low-speed single-threshold comparator to realize the hysteretic band, and can be seamlessly used across all loads in continuous conduction mode and discontinuous conduction mode without modifying the controller's parameters. Moreover, without additional adaptation circuits or frequency regulation loops, the proposed delay-based hysteretic operation does not increase variations in the switching frequency with process and temperature, and results in even less variations in the switching frequency with the input and output voltages when compared to corresponding designs with accurate explicit hysteretic bands. The simplicity of the design reduces silicon area and quiescent current significantly, which in turns enables achieving high efficiency at both heavy and light load conditions as strictly required by low-power microcontrollers. The regulator is designed in a 65 nm digital CMOS technology. It occupies 0.18 mm2 and supports a wide range of input voltages (1.8–4.2 V), output voltages (0.9–1.5 V), and load current (up to 300 mA). Measurement results show that the proposed regulator achieves 95% peak efficiency, while achieving between 62% and 87% efficiency at 10-μA load across all operating conditions. [ABSTRACT FROM AUTHOR]

Demand response (DR) is envisaged to be of significance for enhancing the flexibility of power systems. The distributed nature of residential demand-side resources necessitates the introduction of an aggregator/retailer to represent the flexible demand in the electricity market. However, the objectives of the residential consumers, the retailer, and the system operator might not be aligned. This paper presents a multi-perspective model which integrates the optimization problems of these strategic decision makers within a single framework for evaluation of residential thermal DR. The multi-perspective model is formulated as a bilevel optimization problem and incorporates detailed building state-space models of residential thermal demand. Comparison of the multi-perspective model with existing market-based models shows that it is able to provide a holistic view of residential DR by capturing the interactions in both the retail and wholesale markets. The results also show that centralized optimization models would over-estimate the system value of DR in the presence of strategic market participants. Detailed sensitivity analyses using the multi-perspective model reveal interesting insights on the welfare distribution aspects of DR. The results show that in addition to consumers’ flexibility, retail contract design will also play a major role in determining the welfare distribution among the involved entities. [ABSTRACT FROM AUTHOR]

This paper introduces a novel modeling approach that allows to obtain fast simulations of pulsewidth-modulated dc–dc switched-mode power supplies (SMPS). The proposed methodology combines the use of precise switched models during transient evolutions and averaged models during steady-state or slowly varying conditions. In that way, the resulting mixed modeling approach enables to obtain the detailed switching behavior of SMPS in the context of long-term simulations. The commutation between models is automatically performed in runtime by an algorithm that detects the transient or slowly varying condition according to the evolution of some model variables. When the precise switched model is used, the mentioned algorithm also adjusts the averaged model parameters so that its results are accurate irrespective of the operating point. This paper also describes the implementation of the methodology in the Modelica language and reports simulation experiments showing that the results are as accurate as those obtained using precise switched models, but several times faster. [ABSTRACT FROM AUTHOR]

This paper addresses two problems in the context of two-party communication complexity of functions. First, it concludes the line of research which can be viewed as demonstrating qualitative advantage of quantum communication in the three most common communication “layouts”: two-way interactive communication, one-way communication and simultaneous message passing (SMP). I demonstrate a functional problem $ { \widetilde {cEq}_{T}}$ , whose communication complexity is $O\left ({(\log n)^{2}}\right)$ in the quantum version of the SMP and $\tilde \Omega \left ({ \sqrt {n}}\right)$ in the classical (randomized) version of SMP. Second, this paper contributes to understanding the power of the weakest commonly studied regime of quantum communication–SMP with quantum messages and without shared randomness (the latter restriction can be viewed as a somewhat artificial way of making the quantum model “as weak as possible”). Our function $ { \widetilde {cEq}_{T}}$ has an efficient solution in this regime as well, which means that even lacking shared randomness, quantum SMP can be exponentially stronger than its classical counterpart with shared randomness. [ABSTRACT FROM AUTHOR]

The short-term reliability of the ultra-high-voltage dc (UHVdc) systems has enormous influence on the security of the whole power system. The frequency and duration (F&D) algorithm based on the Markov process (MP) will reduce the accuracy of the short-term reliability indices, due to the exponentially distributed parameters and the strict premises for the state aggregation and combination. In this paper, the short-term aggregation algorithm based on the semi-MP (SMP) is improved. The aggregated transfer rates are obtained by the definition of the semi-Markov kernel elements and the invariability of the transfer probabilities before and after aggregation. The algorithm is applied to the series structure system, which is common in UHVdc. The aggregated kernel matrix and instantaneous transfer probability matrix are derived from those before aggregation directly. A new method is proposed to describe the combined transfer rates by matrices combination and deleting the nonexistent states and transitions, which requires less calculation effort. The Erlang and Weibull distributions are first used to fit the bell-shaped probability density functions (PDFs) of the repair times of the equipments in the UHVdc. The numerical examples show that, compared with the SMP algorithm, the traditional F&D algorithm overestimates the instantaneous equivalent outage hours of the UHVdc. The error is originated from that the F&D algorithm regards the aggregated system as a MP while it is non-Markovian. To show the effectiveness of the bell-shaped repair time, the Erlang and Weibull distributions are compared with the exponential one by the reliability indices. The differences are result from the different PDFs of these distributions. [ABSTRACT FROM AUTHOR]

In this paper, a systematic and analytical study of non-isolated topologies belonging to the family of reduced redundant power processing (R2P2) converters is presented. Based on this study, all the non-isolated R2P2 topologies that can be implemented in reality are derived. Detailed examples clarify all possible cases of this analysis. In addition to this, the voltage ratio and the efficiency for each one of the R2P2 configurations are calculated, being further illustrated with examples. A comparison among configurations is also discussed with criteria the high step-up voltage gain and efficiency, aiming for high-power applications. One of these R2P2 converters is selected for further examination, as the most suitable for such applications. The theoretical analysis, as well as the calculations of the step-up voltage ratio and efficiency of the selected converter, is compared to experimental results conducted on a 2-kW laboratory prototype designed to operate in various step-up voltage ratios and in a high-power range, proving the effectiveness of the proposed investigation. [ABSTRACT FROM AUTHOR]

Task-based programming models such as OpenMP 5.0 and OmpSs are simple to use and powerful enough to exploit task parallelism of applications over multicore, manycore and heterogeneous systems. However, their software-only runtimes introduce relevant overhead when targeting fine-grained tasks, resulting in performance losses. To overcome this drawback, we present a hardware runtime Picos++ that accelerates critical runtime functions such as task dependence analysis, nested task support, and heterogeneous task scheduling. As a proof-of-concept, the Picos++ hardware runtime has been integrated with a compiler infrastructure that supports parallel task-based programming models. A FPGA SoC running Linux OS has been used to implement the hardware accelerated part of Picos++, integrated with a heterogeneous system composed of 4 symmetric multiprocessor (SMP) cores and several hardware functional accelerators (HwAccs) for task execution. Results show significant improvements on energy and performance compared to state-of-the-art parallel software-only runtimes. With Picos++, applications can achieve up to 7.6x speedup and save up to 90 percent of energy, when using 4 threads and up to 4 HwAccs, and even reach a speedup of 16x over the software alternative when using 12 HwAccs and small tasks. [ABSTRACT FROM AUTHOR]

Here, the setup of a three-phase 100 A linear amplifier is proposed. This work focusses on the use of this linear amplifier as power element for machine-emulation. In contrast to common power electronics, a linear amplifier avoids ripple content in the output current caused by switched-mode operation. [ABSTRACT FROM AUTHOR]

This article demonstrates the design and performance of a single-pole single-throw (SPST) microfluidically reconfigurable switch. The switch is formed by placing a microfluidic channel over a microstrip line gap discontinuity. A selectively metallized plate located inside the microfluidic channel is repositioned with fluid flow to capacitively load the discontinuity to achieve the RF switching functionality. Different from prior works based on external micropumps, the SPST switch is integrated with a piezoelectric actuator. The switch layout is optimized to obtain a low actuation time. A switch prototype is characterized to exhibit low insertion loss (0.42 dB) at 30 GHz and wide bandwidth (18 GHz). It operates with rise and fall times down to 1.12 ms. It is actuated by three million switching cycles with no performance degradation. To the best of our knowledge, the presented switch exhibits the lowest reconfiguration time, highest operation frequency, and the highest reliability among the microfluidically reconfigurable devices reported in recent literature. [ABSTRACT FROM AUTHOR]

This letter presents a thermally reconfigurable antenna with beam-direction- and beamwidth-switching capability using origami reflectors with smart shape memory polymer (SMP) hinges. The proposed antenna consists of a single monopole antenna with four origami reflectors. We employ SMP hinges to actuate the origami reflectors. When all origami reflectors are unfolded on the ground plane (Mode I), the monopole antenna exhibits omnidirectional radiation because the reflectors operate as dummies. When two origami reflectors are folded perpendicular to the ground plane, forming a corner reflector (Mode II), the proposed antenna operates as a directional antenna. Beam direction can be switched to 45°, 135°, 225°, and 315° by actuating various origami reflector pairs, with increased peak gain from 4.5 dBi (Mode I) to 11 dBi (Mode II). When one origami reflector is folded perpendicular to the ground plane (Mode III), the 3 dB beamwidth increases from 52° (Mode II) to 140° (Mode III). Beam direction of Mode III can also be switched through 0°, 90°, 180°, and 270° by actuating each origami reflector. The proposed antenna performance was successfully demonstrated from electromagnetic simulation and measurement. [ABSTRACT FROM AUTHOR]

This paper describes a method for estimating model parameters $\varepsilon _{s}$ and $\Delta \varepsilon = \varepsilon _{s} - \varepsilon _{\infty }$ from the peaks in the imaginary permittivity and loss-tangent spectra. The analysis describes how measured parameters obtained from an impedance spectrometer, the magnitude of the impedance, and phase angle, are directly converted into complex permittivity and loss tangent. As an application, the method is used to detect and quantify the crystallization of skim-milk powder, which shows a dramatic change in the Debye parameters as it converts from the amorphous to crystalline state. [ABSTRACT FROM AUTHOR]

In this brief, we consider the anti-windup design for stochastic semi-Markovian switching systems (S-MSSs) with saturation nonlinearity and stochastic disturbance. In the system under consideration, stochastic S-MSSs with the semi-Markovian process can describe more complex systems in a practical control process. The main motivation of this brief is that the practical system described by stochastic S-MSSs always needs to consider the actuator saturation. To deal with this kind of complex problem, sufficient conditions for stochastic stability (SSY) analysis is developed by the Lyapunov function method. Then, the anti-windup strategy is constructed to make the dynamical system achieves SSY and maximize the domain of attraction. Finally, the simulation results of the practical system show the validity of the proposed method. [ABSTRACT FROM AUTHOR]

Summary: This paper analyses current‐fed (current source) isolated dc‐dc converters that are proposed for various renewable energy and dc microgrid applications, such as photovoltaic, fuel cell, or energy storage systems. The analysis addresses current‐fed (boost) full‐bridge converters that achieve clamping and soft switching without dedicated external auxiliary circuits, such as snubbers or clamps. Such converters have certain limitations that can lead to degraded performance and feasibility due to high circulating energy or low silicone utilization at some operating points. The current study reveals these limitations, highlighting advantages and drawbacks of selected snubberless converters at different operating conditions. The relation between the rms input current and the isolation transformer primary current as well as the cumulative rms current of primary semiconductors is used as figure of merit for converter characterization. This approach can be extended and applied to other topology types and used as a universal tool for performance assessment of snubberless converters without auxiliary circuits for particular operating conditions in various systems. [ABSTRACT FROM AUTHOR]

In this paper, a nonisolated high step-up dc/dc converter, belonging to the family of reduced redundant power processing converters (R2P2), is investigated for high-power applications. The selection of this topology as the most suitable for such applications among those belonging to the R2P2 family is justified. Emphasis is given on the theoretical analysis of the real step-up voltage ratio of the converter, and voltage and current stresses under continuous and discontinuous conduction modes of operation, taking into account the nonideality of the topology components, namely the parasitic resistances of semiconductor devices and inductors and the voltage drop of diodes. The theoretical analysis and the behavior of the selected converter are experimentally validated through a 2 kW prototype. Moreover, the overall efficiency of the chosen converter is experimentally investigated for various step-up voltage ratios and for a high-power range, considering a waste heat recovery system for a maritime application. [ABSTRACT FROM AUTHOR]

In the face of a worldwide teacher shortage and, in the United States, a critical shortage of special education teachers, there is an urgent demand for appropriate educational resources. For people with intellectual and developmental disabilities (I/DDs), in particular, there is a compelling need to develop educational tools and strategies to facilitate independence and self-sufficiency and address poor employment outcomes in adulthood. [ABSTRACT FROM AUTHOR]

While the intersection of blockchain and Industrial Internet of Things (IIoT) has received considerable research interest lately, the conflict between the high resource requirements of blockchain and the generally inadequate performance of IIoT devices has not been well tackled. On one hand, due to the introductions of mathematical concepts, including Public Key Infrastructure, Merkle Hash Tree, and Proof of Work (PoW), deploying blockchain demands huge computing power. On the other hand, full nodes should synchronize massive block data and deal with numerous transactions in peer-to-peer network, whose occupation of storage capacity and bandwidth makes IIoT devices difficult to afford. In this paper, we propose a lightweight blockchain system called LightChain, which is resource-efficient and suitable for power-constrained IIoT scenarios. Specifically, we present a green consensus mechanism named Synergistic Multiple Proof for stimulating the cooperation of IIoT devices, and a lightweight data structure called LightBlock to streamline broadcast content. Furthermore, we design a novel Unrelated Block Offloading Filter to avoid the unlimited growth of ledger without affecting blockchain's traceability. The extensive experiments demonstrate that LightChain can reduce the individual computational cost to 39.32% and speed up the block generation by up to 74.06%. In terms of storage and network usage, the reductions are 43.35% and 90.55%, respectively. [ABSTRACT FROM AUTHOR]

In cognitive radio, most spectrum sensing algorithms are model-based and their detection performance relies heavily on the accuracy of the assumed statistical model. In this letter, we propose a convolutional neural network-based deep learning algorithm for spectrum sensing. Compared with model-based spectrum sensing algorithms, our proposed deep learning approach is data-driven and requires neither signal-noise probability model nor primary user (PU) activity pattern model. The proposed algorithm simultaneously takes in the present sensing data and historical sensing data, with which the inherent PU activity pattern can be learned to benefit the detection of PU activity. With extensive numerical simulations, results show that the proposed algorithm outperforms the estimator-correlator detector and the hidden Markov model-based detector in terms of correct detection probability. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of $\mathscr {L}_\infty$ control for positive delay systems with semi-Markov process. The system is subjected to a semi-Markov process that is time-varying, dependent on the sojourn time, and related to Weibull distribution. The main motivation for this paper is that the practical systems such as the communication network model (CNM) described by positive semi-Markov jump systems (S-MJSs) always need to consider the sudden change in the operating process. To deal with the corresponding problem, some criteria about stochastic stability and $\mathscr {L}_\infty$ boundedness are presented for the open-loop positive S-MJSs. Further, some necessary and sufficient conditions for state-feedback controller satisfying $\mathscr {L}_\infty$ boundedness and positivity of the resulting closed-loop system is established in standard linear programming. Finally, the practical system about the CNM is given to verify the validity of the proposed method. [ABSTRACT FROM AUTHOR]

Recent studies have proved that sustainable saturation operation of Ferrite Power Inductors (FPIs) allows reducing the inductor size and increasing the power density in Switch-Mode Power Supply (SMPS) applications. This paper discusses a new behavioral model for reliable prediction of ac power loss in FPIs, including the effects of saturation. The new model has been identified by means of the Genetic Programming (GP) algorithm combined with a Multi-Objective Optimization (MOO) technique, starting from large sets of power loss experimental measurements. The proposed ac power loss model uses as input variables the voltage and switching frequency imposed to the inductor by the SMPS operation, while the dc inductor current is used as a parameter expressing the impact of saturation. Such quantities can be easily determined for whatever converter topology and in real-world switching operation, thus confirming the readiness and the easiness-to-use of the proposed behavioral model. The results of experimental tests presented in this paper prove the reliability of the power loss predictions, also by correctly accounting for the impact of inductors saturation. [ABSTRACT FROM AUTHOR]

Shared mesh protection (SMP) is a protection mechanism that recovers traffic delivery against failures on a working path as rapidly as linear protection. In addition, it allows for resource sharing among the protection paths with different endpoints in a mesh network by coordinating the use of shared resources when multiple protection paths compete for these resources. Owing to limited protection resources and the preemption in consequence of priority comparison, the SMP introduces a new optimization problem whose objective is to find the optimal priority assignment that maximizes the number of protected services against any failure case for a given SMP network. In this paper, we recognize that the problem of finding the optimal solution is NP-hard and propose min-degree and capacity-density approximation algorithms, whose approximation ratios are presented with the maximum degree of services and the maximum capacity of segments of an SMP network. Moreover, we propose a depth-based algorithm that always finds the optimal solution for a hypertree-shaped SMP network. We compare the performance of the proposed algorithms in terms of the protection ratio, which we define in this paper. [ABSTRACT FROM AUTHOR]

In many applications, including integer-forcing linear multiple-input and multiple-output (MIMO) receiver design, one needs to solve a successive minima problem (SMP) on an $n$ -dimensional lattice to get an optimal integer coefficient matrix $\boldsymbol {A}^\star \in {Z}^{n\times n}$. In this paper, we first propose an efficient optimal SMP algorithm with an ${\mathcal {O}}(n^{2})$ memory complexity. The main idea behind the new algorithm is it first initializes with a suitable suboptimal solution, which is then updated via a novel algorithm with only ${\mathcal {O}}(n^{2})$ flops in each updating, until $\boldsymbol {A}^{\star }$ is obtained. Different from existing algorithms which find $\boldsymbol {A}^\star $ column by column through using a sphere decoding search strategy $n$ times, the new algorithm uses a search strategy once only. We then rigorously prove the optimality of the proposed algorithm. Furthermore, we theoretically analyze its complexity. In particular, we not only show that the new algorithm is $\Omega (n)$ times faster than the most efficient existing algorithm with polynomial memory complexity, but also assert that it is even more efficient than the most efficient existing algorithm with exponential memory complexity. Finally, numerical simulations are presented to illustrate the optimality and efficiency of our novel SMP algorithm. [ABSTRACT FROM AUTHOR]

Microfluidically switched feed networks are introduced to realize millimeter-wave beam-steering focal plane arrays (FPAs). Switching functionality is achieved by a selectively metallized plate (SMP) repositionable within a microfluidic channel that is brought in close proximity to the microstrip line feed network of an FPA. The feed network is strategically designed to exhibit gap discontinuities that are sequentially overlapped by the SMP metallizations. The capacitive couplings between the SMP metallizations and the gap discontinuities are designed to achieve wideband (~20 GHz) switching functionality with low insertion loss (IL < 0.2 dB). Transmission line theory is utilized to demonstrate that the feed network offers 38% fractional bandwidth with ≤7 dB IL for linear arrays of 32 elements. This performance constitutes a significant improvement over the recently reported resonant feed network based realization of microfluidic beam-steering FPAs (MFPAs). Experimental verification is carried out through the design and fabrication of a 30 GHz eight-element FPA. The FPA exhibits measured gains ranging between 20.2 and 22.6 dBi. Loss budget breakdown confirms the low-loss performance of the microfluidically switched feed networks (≤3 dB). The required microfluidic actuation range is 4.2 mm and $10\times $ lower than that of the prior work. This allows to achieve a faster beam-steering speed (0.27 s versus 5.25 s of previous designs). An integrated sensing approach for detecting the SMP position is also presented for the first time to facilitate the use of presented MFPAs with closed-loop position control. [ABSTRACT FROM AUTHOR]

Spread-spectrum (SS)-based pulsewidth modulation (PWM) techniques play an important role when tackling the electromagnetic interference (EMI) problem in the switch-mode power supply (SMPS) domain. They achieve the best EMI noise reduction and emerge as a promising and very effective solution to comply with electromagnetic standards. The current work provides an insight into the SS techniques: its history, its types, and mainly its ability to mitigate the EMI problem in the SMPS domain. Moreover, it gives a short review of the different SS-based PWM techniques going from the most basic and simple, i.e., the periodic modulation, to the most developed and complex, i.e., the random and chaotic modulations. Besides, a short review of the different implementation methods was addressed and they were categorized into analog and digital implementation techniques where its pros and cons were provided. Finally, a new fast digital implementation method based on a dsPIC33F microcontroller is presented. Its effectiveness was proved and its advantages over the reviewed implementation techniques were recognized. It reached a 20 dBuV EMI level reduction when the digital chaotic and periodic profiles were embedded into a boost converter prototype. [ABSTRACT FROM AUTHOR]

Magnetic components in power electronic equipment usually suffer from nonsinusoidal excitations. In this paper, a brief description about the existing core loss calculation methods for nonsinusoidal excitations is given. Then calculation formulas of aforementioned methods for two typical excitation waveforms, that is, square and rectangular with variable duty cycle ${D}$ , are derived. Core loss of nanocrystalline FT-3KS, under above two nonsinusoidal excitations, is measured on an established test setup. The accuracy and applicability of each method are discussed theoretically and verified experimentally, especially in terms of different duty cycles and frequencies. It is found that the waveform coefficient Steinmetz equation (WcSE) is more applicable for the case of relatively small harmonics content of magnetic field intensity ${H}$ (normal duty cycle region), while the improved generalized Steinmetz equation (IGSE) has better precision where the harmonics count (extreme duty cycle region). In addition, the IGSE can better follow the changing trend of core loss with ${D}$ and have better frequency applicability than WcSE, which is proven to be not valid in low frequency (where the static hysteresis loss dominates). The results can provide reference for core loss prediction under nonsinusoidal excitations. [ABSTRACT FROM AUTHOR]

In this paper, we propose a sparse signal estimation algorithm that is suitable for many wireless communication systems, especially for the future millimeter wave and underwater communication systems. This algorithm is not only asymptotically optimal, but also robust to the distribution of nonzero entries of the sparse signal. Then, we derive its upper bound and lower bound, and show that the mean square error of the proposed algorithm can approach the minimum mean square error bound when the signal noise ratio goes to infinite or zero. Numerical simulations verify our theoretical analysis and also show that the proposed algorithm converges faster than existing algorithms, e.g., turbo-type signal recovery-discrete fourier transform, approximate message passing, etc. [ABSTRACT FROM AUTHOR]

As multimedia services are gaining considerable popularity in the Internet of Things, providing QoE in smart mmIoT becomes a challenging issue. This article conceptualizes a new framework named SMP, to price the QoE rather than the binary data traffic in IoT multimedia services. By introducing PaaR in QoE-driven network scheduling in mmIoTs, a new dimension of price distortion is available in multimedia resource allocation, complementing traditional rate distortion and power distortion resource allocation approaches. This article also discusses open research challenges in SMP resource allocation, including the difficulty of numerical presentation of QoE, the unavailability of packet-level distortion information, and the non-concavity of the utility functions. A case study is presented to illustrate the PaaR potentials of improving QoE through the SMP framework in mmIoTs. [ABSTRACT FROM AUTHOR]

This paper proposes a circuit structure that can improve the power-conversion efficiency \eta e of an AC–DC boost converter. The circuit uses a 1:1 transformer and a voltage boost circuit composed of an inductor, a capacitor, and a diode. The transformer forces the converter to operate in continuous conduction mode for input current, and thereby reduces input ripple. The voltage boost circuit enables the switch to operate in critical conduction mode, so the power loss due to turn-on of switch and reverse recovery of diode is minimized. The proposed converter has high \eta e over a wide range of AC input voltage $V_{{\rm{ac}}}:\,\eta _{e}= 92.9\% $ at $V_{{\rm{ac}}}= {\text{85}}\,{\text{V}} and \eta e= 97.4\% at V{\rm{ac}}= {\text{265}}\,{\text{V}}, when the converter was operated at DC output voltage of 400 V and output power of 500 W. The temperature of the switch stabilized at ∼84 °C for $V_{{\rm{ac}}}= {\text{85}}\,{\text{V}}$ , at ∼70 °C for $V_{{\rm{ac}}}= {\text{110}}\,{\text{V}}$, and at ∼42 °C for $V_{{\rm{ac}}}= {\text{220}}\,{\text{V}}$, whereas that in other AC–DC converters either failed or stabilized at much higher levels. The proposed converter is well suited to systems that require an input voltage range of 85–265 V in root-mean-square value. [ABSTRACT FROM AUTHOR]

Achieving fast wireless access speeds in an already restricted bandwidth (as the frequency spectrum is a finite resource) necessitates highly spectrally efficient communications standards that combine both amplitude-modulation (AM) and phase-modulation (PM). The resulting complex modulation schemes require that the RF power amplifier (PA) be highly linear to preserve the modulation and, hence, the transmitted data (in-band linearity) and simultaneously avoid interfering with users of the rest of the spectrum (out-of-band linearity). Unfortunately, in PA design, linearity and efficiency are contradictory goals; typically, highly linear PAs demonstrate low efficiency and, hence, reduced battery life [1]. [ABSTRACT FROM PUBLISHER]

The visible light communication (VLC) can provide data transmission via the illumination light emitting diodes (LED). This paper introduces a new model to analyze the bit error rate (BER) of binary phase modulation in VLC for an arbitrary modulation depth and data duty cycle while taking into account both the Gaussian and signal-dependent shot noise. The impact of the driver design on the BER and its impact on ripple have not been considered in detail before. We compare two different LED driver schemes, namely directly adapting the driver control loop and binary shunting. We address data rate, BER, and power efficiency, for which we propose to use the extra energy per symbol above unmodulated light. We further introduce an analysis of the effect that (truncated) ripple interference has in the (matched or other) filter of the receiver. Ripple causes a harmful interference in VLC, and thus a BER expression is derived to include its effect. Two approximations are proposed to model the ripple interference, and their accuracies are compared by simulations. A low-pass filtering is proposed to alleviate the impact of ripple interference in VLC system. [ABSTRACT FROM PUBLISHER]

Cache Coherent NUMA (ccNUMA) architectures are a widespread paradigm due to the benefits they provide for scaling core count and memory capacity. Also, the flat memory address space they offer considerably improves programmability. However, ccNUMA architectures require sophisticated and expensive cache coherence protocols to enforce correctness during parallel executions, which trigger a significant amount of on- and off-chip traffic in the system. This paper analyses how coherence traffic may be best constrained in a large, real ccNUMA platform comprising 288 cores through the use of a joint hardware/software approach. For several benchmarks, we study coherence traffic in detail under the influence of an added hierarchical cache layer in the directory protocol combined with runtime managed NUMA-aware scheduling and data allocation techniques to make most efficient use of the added hardware. The effectiveness of this joint approach is demonstrated by speedups of 3.14x to 9.97x and coherence traffic reductions of up to 99 percent in comparison to NUMA-oblivious scheduling and data allocation. [ABSTRACT FROM AUTHOR]

In mobile platforms, RF interference issues caused by the switched-mode power supply (SMPS) ringing noise often arise in the on-the-go mode and the charging mode of the interface power management integrated circuits. In this paper, we introduce the modeling method for the SMPS ringing noise in the conventional two-level dc–dc converters and then, based on the modeling insight from the two-level dc–dc converter, we investigate and validate the modeling of the SMPS ringing noise in the three-level buck converters, which are newly adopted SMPSs for fast charging in mobile devices. To reduce such noise, we propose the novel SMPS noise-managing methodologies that handle the printed-circuit-board-level design optimization in mobile devices. [ABSTRACT FROM PUBLISHER]

With ever-increasing demand of feature-rich portable electronics, single-inductor multiple-output (SIMO) converters are becoming a cost-effective option to provide different supply voltages while maintaining a long battery life. A single-discharge (SDC) control scheme is proposed to simplify the SIMO design, to achieve low cross-regulation, and to support wide range of loads with reasonable power efficiency. A SDC SIMO buck converter with four outputs composed of comparators, phased-locked loop, finite state machine (FSM) controller, and an output stage, is prototyped using TSMC's 0.18-μm BCD process. In addition to the basic switching functions, the FSM controller provides a state skipping feature to allow no-load regulation. Its functionality is verified experimentally and can convert an input voltage from 2.7 to 3.7 V to 1, 1.2, 1.5, and 1.8 V outputs. The simulated peak power conversion efficiency is 86% with a combined output power ranging from 150 to 300 mW. The packaged SDC SIMO converter ICs exhibit a lower measured peak efficiency of 73%, with a cross-regulation of 0.24 mV/mA due to the parasitic bond-wire resistance. The converter prototype can support a wide range of loading conditions, from open circuit to a total output power of 1 W. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a new capacitor degradation evaluation method aimed at failure prediction and suitable for digitally controlled switching mode power supply (SMPS) for servers. Electrolytic capacitors have one of the highest component failure rates in SMPS; therefore, we attempt to detect an equivalent series resistance degradation of the electrolytic capacitor directly from the data fetched to a digital controller of the SMPS. With a SPICE simulation and a rapid control prototyping evaluation, we confirm the degradation can be detected by the data at a transient response under a normal operation without additional circuits. Even only 10% of a load step change, which commonly occurs in SMPS for servers, causes detectable transient response degradation. [ABSTRACT FROM PUBLISHER]