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AbstractThe electrical characterization of materials, particularly superconductors, semiconductors, and those undergoing metal-insulator transitions (MITs), relies significantly on resistivity and Hall measurements as a function of temperature. The van der Pauw four-point probe method is commonly used for such measurements, which involves resistance measurements for different circuit configurations connected to sample contacts. However, repeating these measurements at different temperatures is challenging and time consuming. This study introduces a novel approach utilizing a switching circuit controlled by an Arduino device and a LabVIEW program to automate resistance measurements for different electrical configurations. The effectiveness of this setup was demonstrated by testing V2O3 thin film samples deposited on Al2O3 (001) substrates using DC magnetron sputtering. The MIT temperature of the sample was 115 K during heating and 100 K during cooling. The sample exhibited p-type charge carriers with a Hall coefficient of 1.3 ± 0.1 x 10−4 cm3/C and Hall mobility of 1.7 x 10−1 cm2/V∙s, which is consistent with findings from other studies employing commercial equipment. [ABSTRACT FROM AUTHOR]

In the current communication era, 2G voice services coexist with higher generation mobile network voice services like Voice over Long Term Evolution (VoLTE) in 4G and Voice over New Radio (VoNR) in 5G. Subscribers registered in the 5G network, but their voice option is in 4G so voice calls can be handled through the Evolved Packet System (EPS) Fallback or Radio access technology (RAT) Fallback. Similarly, subscribers register in a 4G network, but their voice option is in 3G or 2G so voice calls can be handled through Circuit Switched Fallback (CSFB). To provide uninterrupted voice service in such wireless networks usually handoff calls (HCs) receive higher priority than new calls (NCs). So, some guard radio resources (i.e., channels in 2G or RBs in 4G or 5G) may be reserved in each cell to handle this type of HCs. If more channels are reserved for HCs, then the handoff call-dropping probability (HCDP) will be decreased and at that time the new call-blocking probability (NCBP) will be increased. So, by considering the target HCDP if channels are reserved for HC, then HCDP will remain below the target and NCBP will be minimum. In this paper first, we proposed an optimal channel reservation (OCR) policy that reserves guard channels according to the given target HCDP. Second, we compared our OCR policy with fractional channel (FC), limited fractional channel (LFC), and uniform fractional channel (UFC) policies. Finally, we observed the performance of all these policies considering the Global System for the Mobile Communication (GSM) network. [ABSTRACT FROM AUTHOR]

Due to the reduction in transistor size, test engineers face a severe issue in power minimization. VLSI circuit's power dissipation has become a vital concern due to the switching activity of the Circuit Under Test (CUT). Switching activity is a significant factor in determining power consumption for CMOS VLSI circuits. In this paper, we formulate a distance estimation technique and reordering using the Tversky index. Here, the distance between the test vectors is calculated using the Tversky index with the formation of an adjacency matrix, and reordering is performed. The experimental results of the proposed method have been compared to different distance measures and existing techniques. It shows that the switching activity is reduced from 52.5% to 21.5%, and the average power reduction is from 42% to 14.6% when the distance is estimated on reordering using the Tversky index measure. Thus, the Tversky index distance measure performs better than the Hamming, gray, and Linear feedback shift register (LFSR) methods. Switching activity estimation for complex ISCAS circuits has been performed and compared with existing methods for superior performance. We have also developed a Built in Self-Test (BIST) for the C17 benchmark circuit, which uses the Tversky counter as a test pattern generator using the TANNER EDA tool. Thus, an efficient deterministic BIST for the C17 benchmark circuit was designed to detect all the stuck-at faults, and the same procedure can be used to create BIST for all CUT and precomputed test sets for real-time field testing. [ABSTRACT FROM AUTHOR]

In this paper, we present an easy and systematic design approach to realize a dual beam reflector antenna at Ka-band which produces a narrow beam and a wide beam in the boresight. These two beams can be independently selected mechanically or by means of an electronic switching circuit. An exclusive systematic design approach has been presented. Simple mathematical expressions have been used for the design of the reflector and feed horns. The complete antenna has been realized with aluminum and its performances were experimentally validated. It yields ≈11.44% impedance bandwidth. It produces ≈ 35.4 dBi gain in the narrow beam mode with a half power beamwidth of ≈ 4.4° × 3.7° and about ≈ 11.3 dBi gain in the wide beam mode with a 3 dB beamwidth of ≈ 46.5° × 46° at 28 GHz. In this present work, the patterns are swapped between a narrow-beam and a wide-beam in the broadside. The ratio of the wide-beamwidth to the narrow-beamwidth is about 11:1, which is substantially different from all earlier investigations. [ABSTRACT FROM AUTHOR]

This research aims to design a robust adaptive tracking controller for Chua's switched nonlinear circuit systems. The proposed adaptive composite nonlinear approach is modified in order to provide a robust controller with improved performance in the presence of uncertainties and input saturation. It is demonstrated that by employing an integral sliding mode controller that is based on a linear matrix inequality (LMI), the resultant closed-loop system can attain an exponentially boundedly stable. This technique ensures robustness to the impacts of uncertainties and input saturation and reduces the chattering phenomenon. Eventually, a simulation example of Chua's circuit system is utilised to reveal the performance and advantages of the offered approach. [ABSTRACT FROM AUTHOR]

A high conversion gain, low noise up-conversion mixer for 5G New Radio band (850 MHz) Internet of Thing (IoT) applications implemented in UMC 0.18 μm standard CMOS technology is presented. The proposed mixer is based on the Flipped voltage follower current mirror with a passive switching circuit. The proposed up-conversion mixer achieves a noise figure (NF) of 4.4 dB, maximum Conversion Gain (CG) of 33.85 dB, maximum input third-order intercept point (IIP3) of 33.16 dBm, and output third-order intercept point (OIP3) of 11.89 dBm. It has a total power consumption of 23.58 mW with a 1.2 V supply voltage. The overall chip area of the design is 26.5 µm × 54.9 µm. [ABSTRACT FROM AUTHOR]

This paper introduces a new structure of a multi-level inverter (MLI) to generate high-level AC voltages using a low number of switches with a quasi-sine waveform. The small number of driver circuits utilised in bidirectional switches is a salient characteristic of this inverter. Also, the number of conducting switches at each voltage level is low in this structure. This results in lower conduction losses of the switches. The proposed topology can be used as the cascaded structure with different approaches to select the value of voltage sources. Power losses are discussed for the proposed structure. To compare the proposed multi-level inverter and demonstrate its superiority, a comparison has been made with some recently presented topologies. According to the comparison results, the advantage of the proposed structure is producing high voltage levels with a smaller number of switches and driver circuits. To prove the suitable performance of the proposed MLI, a 21-level symmetric and 37-level asymmetric inverter containing 14 switches are designed and simulated in the MATLAB/Simulink program. A laboratory prototype for each of these inverters is implemented. The experimental results finely verify the simulations. Besides, an accurate comparison with recently introduced multilevel inverters has been carried out to confirm the effectiveness and superiority of the proposed structure. [ABSTRACT FROM AUTHOR]

In this paper, a nine-level inverter topology is proposed with the least number of switches and other components for fault tolerant (FT) operation. The proposed fault tolerant topology requires only one additional switch to execute the fault tolerant operation. The proposed topology also results in reduced total harmonic distortion (THD) as compared with other reported fault tolerant topologies for a 9-level output. A detailed analysis of the topology is presented and the fault tolerant operation is demonstrated under any single, double, triple, and quadruple switch faults using MATLAB/ Simulation and OPALRT hardware in loop (HIL) real time simulator. The proposed concept is validated for single and multiple switch faults and R-L load variation on a low scale laboratory hardware set-up. [ABSTRACT FROM AUTHOR]

Multilevel Inverters (MLI) created a milestone due to increasing demand in high power medium voltage applications. To decrease the harmonics content and stress across power semiconductor devices, multilevel inverters are used. In this paper, a nine-level inverter is presented with a auxiliary circuit that requires a minimum number of power devices compared to the traditional MLI topologies. The suggested nine-level inverter's control circuitry is controlled by an ATmega8 microcontroller in this study. Opto-isolators with galvanic isolation supply the triggering pulses to operate switches. A nine-level inverter to power 100 W load is implemented using two proposed auxiliary circuits for renewable energy applications. The presented nine-level inverter's control switches are driven using a DC level shifting method. The suggested inverter's functionality and feasibility are confirmed by the experimental and simulation findings. [ABSTRACT FROM AUTHOR]

Raining, fog, lightning, insulation failure and short circuit are the major reason for fault occurrence in smart grids of distribution systems. This work arranges the distribution system as a radial network (closed loop structure). Generally, the radial network is suffered from both transient and permanent faults. This work uses the harris hawks optimization (HHO) algorithm to find and isolate such faults. Self-isolation separates faulted sections from the distribution system to provide a nonstop power supply. Accurate self-identification and permanent isolation of faulty sections are the main objective functions of HHO, which reduces the complexity and energy loss of the self-isolation process. The harris hawks optimized self-isolation (HHOSI) algorithm continuously monitors the smart grid relays, switches and circuit breakers through a wireless sensor network (WSN) to identify the faulty part. The proposed algorithm is implemented in the MATLAB platform and analyzed the performance of a self-isolation scheme for 5 minutes. As a result, the proposed method attains 32.38% performance improvement over AEC and 18.06% over the LO-ADI method. [ABSTRACT FROM AUTHOR]

Discrete-time queueing systems have widespread applications in packet switching networks, internet protocol, Broadband Integrated Services Digital Network (B-ISDN), circuit switched time-division multiple access etc. In this paper, we analyze an infinite-buffer discrete-time group-arrival queue with single and multiple vacation policy where processing/transmission/service times dynamically vary with batch-size under service. The bivariate probability generating function of queue length and server content distribution has been derived first, and from that we extract the joint probabilities in terms of roots of the characteristic equation. We also find the joint distribution at arbitrary and pre-arrival slot. Discrete phase type distribution plays a noteworthy role in order to regulate the high transmission error through a particular channel. In view of this, numerical illustrations include the service time distribution to follow the discrete phase type distribution. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of hybrid control for a class of switched uncertain systems. The switched system under consideration is subject to structured uncertain dynamics in a linear fractional transformation (LFT) form and time-varying input delays. A novel hybrid controller is proposed, which consists of three major components: the integral quadratic constraint (IQC) dynamics, the continuous dynamics, and the jump dynamics. The IQC dynamics are developed by leveraging methodologies from robust control theory and are utilised to address the effects of time-varying input delays. The continuous dynamics are structured by feeding back not only measurement outputs but also some system's internal signals. The jump dynamics enforce a jump (update/reset) at every switching time instant for the states of both IQC dynamics and continuous dynamics. Based on this, robust stability of the overall hybrid closed-loop system is established under the average dwell time framework with multiple Lyapunov functions. Moreover, the associated control synthesis conditions are fully characterised as linear matrix inequalities, which can be solved efficiently. An application example on regulation of a nonlinear switched electronic circuit system has been used to demonstrate effectiveness and usefulness of the proposed approach. [ABSTRACT FROM AUTHOR]

In energy harnessing applications there are instances where energy should be transferred from a low-power, low-leakage backup battery to a temporary power delivery output capacitor. The high power delivery feature of the storage capacitor usually comes at the price of higher leakage current and thus it cannot replace the long-term energy storage backup battery. This paper presents a CMOS capacitor charger circuit which connects a long term low power battery to a short-burst high power delivery capacitor. The proposed circuit uses a switching output stage with an external inductor to reduce the dissipation during the capacitor charge-up cycle. A sigma-delta modulation approach is used to control the power switches. Under low power transfer scenarios which perform transfer in a longer duration, the proposed approach shows better performance compared with previously presented techniques. It is shown that under different transfer durations the control section only consumes 970nWs. The efficiency of the proposed circuit is more than 90% for average input powers in the 0.7 mW to 2 mW range. [ABSTRACT FROM AUTHOR]

In this paper, a higher level symmetrical and asymmetrical multilevel inverter (MLI) with reduced device count is proposed for renewable energy systems. Multilevel inverters are recently gaining importance in renewable energy systems and other DC to AC conversion applications due to reducing voltage stress, low total harmonic distortion (THD) and high-quality output as compared to classical inverters. This paper present a basic cell unit of reduced device count (RDC) MLI with six switching devices is proposed. The topology has advantages of reduced device count over existing topologies for the same number of output levels, thus improving operating efficiency and reliability. Upon cascading two such basic cells with 12 devices synthesizes a 49 level output with an estimated THD of 1.63%. The other advantages accrued due to reduced device count are a reduction in switch driver circuits, less number of required dc voltage sources, less installation space and reduction in cost. The major benefit of the proposed topology is that it can deliver power from an asymmetrical source to load even under sudden variation in environmental conditions. The proposed MLI topology is simulated in MATLAB/Simulink environment and a laboratory prototype is developed and tested in the lab. The control paradigm is developed as the Simulink model, which is interfaced with dSPACE DS-1104 for generating control pulses to drive switches of proposed MLI topology. The experimental results validate the concept and paradigm of the proposed MLI topology. [ABSTRACT FROM AUTHOR]

Nowadays, manufacturing control systems can respond more effectively to exigent market requirements and real-time demands. Indeed, they take advantage of changing their structural and behavioural arrangements to tailor the control solution from a diverse set of feasible configurations. However, the challenge of this approach is to determine efficient mechanisms that dynamically optimise the configuration between different architectures. This paper presents a dynamic hybrid control architecture that integrates a switching mechanism to control changes at both structural and behavioural level. The switching mechanism is based on a genetic algorithm and strives to find the most suitable operating mode of the architecture with regard to optimality and reactivity. The proposed approach was tested in a real flexible job shop to demonstrate the applicability and efficiency of including an optimisation algorithm in the switching process of a dynamic hybrid control architecture. [ABSTRACT FROM AUTHOR]

Sediment microbial fuel cells (SMFCs) have served as an alternative technique to suppress phosphorus release from lake sediments to water bodies and thus mitigate eutrophication. However, the phosphorus regulation mechanism remains unclear. The purpose of this research was to understand the electrochemical influence of an SMFC on the phosphorus concentration in interstitial water. In this study, a lab-scale SMFC was applied to acetate-spiked sediments (ace+) and unspiked sediments (sed) with closed-circuit (CC)/open-circuit (OC) columns, and the circuitry was switched to investigate the relationship between electron transfer and phosphorus concentration. The dissolved total phosphorus (DTP) concentration in the sediment interstitial water in CC columns significantly decreased to below 0.1 mg/L, whereas the DTP in OC columns remained high for nine weeks. After switching the circuit, the DTP in OC→CC columns dropped but that in CC→OC columns increased within one week. At the end of the experimental period, the DTP concentrations in CC/sed, CC/ace+, OC/sed, and OC/ace+ columns were 0.10 ± 0.02, 0.03 ± 0.00, 0.82 ± 0.01, and 1.66 ± 0.12 mg/L, respectively. The respective estimated anode capacitances of those columns were 2.05 ± 0.49, 5.15 ± 0.14, 0.72 ± 0.19, and 0.71 ± 0.12 nF. We concluded that the phosphorus may have been electrochemically attracted and retained on the anode in the sediment because the adsorbed DTP contents and the increased anode capacitances were strongly correlated. Thus, SMFCs can be used for suppressing phosphorus release from eutrophic lake sediments. [ABSTRACT FROM AUTHOR]

The solar photovoltaic system often encounters partial shading issues which invariably affect the output power generation from the PV array. Partial shading conditions cannot be discarded but able to be diminished using reconfiguration techniques. A new square dynamic reconfiguration algorithm is critically analyzed in this paper for the partial shaded Photovoltaic System. However, several other dynamic reconfiguration algorithms exist, the proposed square dynamic reconfiguration technique extracts maximum power from the PV array using a feasible switching circuit. In this method, an 8 × 8 PV array splits into four quadrants of each 4 × 4 matrix is investigated and a switching matrix is introduced between the quadrants in this proposed square dynamic reconfiguration algorithm. Each quadrant possesses an equal number of rows and columns. The row current in terms of the short circuit current of each row is utilized to categorize the different cases. The simulation work of this proposed SDR method is conducted in MATLAB Simulink software for 8 × 8 matrices and the experimentation is accomplished using a test setup of a 4 × 4 PV array. Randomly seven shading types are considered to verify the effectiveness of our work. In the switching matrix, only 16 switches are taken to extract a maximum power of 136 W out from the 160 W experimentation 4 × 4 PV array test set up under partial shading. The herein conducted research work provides an innovative and simpler reconfiguration algorithm because of its lesser number of switches in the switching circuit with a convenient operation to generate power during partial shading conditions. [ABSTRACT FROM AUTHOR]

In this paper, an Isolated Three-Port Interleaved Flyback Boost Converter (ITPIFBC) operated micro-inverter is presented to interface the Photovoltaic (PV) power generation system with the three-phase power distribution network. The integration of interleaved flyback boost circuit reduces the switching and conduction losses of the converter. The addition of a voltage multiplier circuit in the secondary side of the high-frequency transformer enhances the voltage gain and reduces the voltage stresses of the semiconductor devices used in the rectification part of the circuit. The introduction of a voltage multiplier circuit reduces the required turn's ratio, power rating and voltage rating of the IGBTs and diodes. The duty cycle of the converter controls the power flow between the two independent power sources. The voltage control loop incorporated with the maximum power point tracking algorithm regulates the output voltage of the converter. In this work, the design, operation principle and implementation of the ITPIFBC based micro-inverter are discussed. The dynamic behavior of the proposed micro-inverter is validated by developing the 4 kW, 400 V model in both software and hardware. The simulation and experimental results showed the superior performance of the ITPIFBC converter in boosting the input voltage under various test conditions. [ABSTRACT FROM AUTHOR]

An improved Random Swapping Thermometer Coding (RSTC) Dynamic Element Matching (DEM) method is presented for Nyquist-rate Digital to Analog converters (DACs). In contrast to the RSTC DEM method, the presented method prevents the Spurious-free dynamic range (SFDR) reduction in DACs in low signal frequencies. Also, while "RSTC with the restricted jumping technique" method is unable to prevent the SFDR reduction in low frequencies for non-full-scale sinusoidal signals, this new method prevents the SFDR reduction in low frequencies for both full-scale and non-full-scale sinusoidal signals. The Fast fourier transform (FFT) analysis for a behavioural model of a 6-Bit thermometer coded DAC at F i n = 0.02 F s ( F i n is the signal frequency and F s is the sample rate) shows 2.1 dB SFDR improvement in comparison to "RSTC with the restricted jumping technique" method. In addition, the presented method achieves a reasonable trade-off between SFDR and Switching activity in comparison to other DEM methods. [ABSTRACT FROM AUTHOR]

Dopingless Tunnel Field Effect Transistor is a prominent device because of its low sub-threshold swing and fast switching speed. In this paper, DL-TFET is investigated for enhancing the performance parameters by applying different engineering techniques. The hetero-junction is implemented in the DL-TFET for increasing the ION current. Further, for reducing the ambipolar current and enhancing the ON-characteristics by introducing the non-uniform oxide layer, hetero-gate and then further optimization is done by varying the "x" compositions of In1-xGaxAs for source side material. The various staggered hetero-gate hetero-junction DL-TFET structures with different EBeff are comparatively investigated for analyzing their performance parameters. Among them, highly staggered Hetero-junction DL-TFET with EBeff = 0.374 eV shows better performance as lower threshold voltage, higher ION current, high transconductance and lower sub-threshold swing. So, the In0.45Ga0.55As/In0.25Ga0.75As based hetero-gate at TG = 4.2 eV and Θ = 7.59° heterojunction DL-TFET structure can be chosen for fast switching and advanced circuit application. [ABSTRACT FROM AUTHOR]

Inverter-based distributed generation (DG) units in microgrid (MG) call for robust and precise control methods that attain high performance under both normal and unbalanced conditions. Efficient control scheme needs to be investigated for the proper operation of a microgrid in both grid-tied and islanding condition. Using the excellent performance of slide mode controller(SMC) for nonlinear loads and the ability of proportional resonant(PR) controller to precisely track reference sinusoidal signal, a cascaded SMC and PR controller has been proposed for stable operation of microgrid. The phenomenon of chattering a drawback in SMC is eliminated by using fixed frequency switching of the inverter circuit using smooth control law in a narrow boundary layer. For effective sharing of the loads among different DER's during isolation mode of operation a droop controller is proposed. The proposed controller showed excellent results for linear and nonlinear loading. To analyze the performance of droop controller, proposed for parallel operation of two DG units, simulations are performed under linear and distorted load conditions. Results obtained shows that proposed cascaded controller and droop controller improves the output by the reduction of the total harmonic distortion (THD), high degree of robustness, fast response time, and efficient power sharing among DG units. [ABSTRACT FROM AUTHOR]

This paper deals with the fault detection observer design problem for switched system with all modes unstable. First, the error system model is presented. With the consideration of the instability caused by the unobservable condition of (A i , C i) , a switching signal is obtained via average dwell time method and discretised Lyapunov function. By means of linear matrix inequalities, sufficient conditions pledging exponential stability and H ∞ performance are proposed. Through transferring the observer design problem into H ∞ performance analysis, proper observer gain is obtained via solving these LMIs. In the end, the validity of the proposed Luenberger observer is verified by an example. [ABSTRACT FROM AUTHOR]

Wireless Mobile Communications have undergone major "generational" changes since MacDonald of Bell Telephone Laboratories introduced the concept of cellular communications in 1979. Over the last four decades, the technology has evolved from the first generation, 1 G, followed by 2 G, 3 G, and 4 G, to reach today's threshold of the fifth generation, 5 G. In order to grasp the magnitude of the impact 5 G is having on our society (5 G internet is expected cover up to 65% of the world's population by the end of 2025!), it is essential to understand the historical development of the previous generations. This review describes and explains the technology from 1 G to 4 G, culminating with the current state-of-the-art of 5 G, and its expected performance over the next ten years. We cover the major technical features of 5 G that differentiate them from the previous generations, in particular,the introduction of the MM-Wave spectrum combined with MIMO, Multiple Input-Multiple Output antenna arrays. We single out these two features as they provide orders of magnitude increases in channel capacity (20 Gb/s Downlink data transfer rates with reduced latency of 1 ms) and internet connectivity on the order of billions. We conclude with related 5 G marketing data, some of it related to the smart phone, a marvel of engineering and a credit to human creativity. 5 G is committed to connecting billions of devices with billions of people, both wirelessly and via the internet. Such a technical advance is a game-changer! [ABSTRACT FROM AUTHOR]

Rapid developments in the field of high-power, high-voltage applications have led to a tremendous increase in the popularity and utility of multilevel inverters. The requirement of reduced harmonics coupled with an ever-increasing demand for clean and renewable energy sources has led to a great interest in the multilevel inverter. This paper presents a novel architecture of a single-phase multilevel inverter that utilizes fewer power electronic switches and driver circuits than various popular multilevel inverter circuits. The design presented is generalized in nature, thereby allowing for the generation of any number of levels in the output voltage. The working and modes of operation of the 9-level symmetrical configuration of the proposed topology is extensively elaborated. Simulation results from MATLAB Simulink as well as real-time hardware results have been included to verify the existence and proper working of the proposed 9-level symmetrical and 15-level asymmetrical inverter. Comparison results with other discussed configurations are also included to further establish the advantages possessed by the proposed circuit. [ABSTRACT FROM AUTHOR]

This paper introduces a Four-Switch Three-Phase Shunt Active Power Filter (FSTP-APF) based on One Cycle Control (OCC) technique for compensating the currents of three phase non-linear loads. The power stage of FSTP-APF uses only four semiconducting switches which leads to reduce the overall cost of APF. The proposed technique retains the advantages of the conventional OCC, such as no reference current calculation, no need for using Phase-Locked Loop (PLL), very simple control circuit and constant switching frequency. In addition, the modification reduces the number of semiconductor switches, reduces the filter output inductances, reducing the number of sensors to only four sensors, two of them for measuring supply currents and the others for measuring DC-link voltages, and the control algorithm becomes simpler. The feasibility and performance of the proposed technique are demonstrated through the simulation and experimental verifications. [ABSTRACT FROM AUTHOR]

A low-profile multi-input-multi-output (MIMO)/diversity antenna suitable for wireless local area network (WLAN) applications is presented. In the proposed antenna, two identical elements (each of size 20 × 47 mm2) are designed to operate at 2.4 GHz and other two identical elements (each of size 20.5 × 20 mm2) at 5.8 GHz. All elements of the proposed diversity antenna are printed on 1.6 mm thick FR-4 substrate in a coplanar configuration. By optimizing the distance between the antenna elements (in horizontal and vertical directions), optimal isolation and diversity performance are achieved. Compared to a single feed dual-band antenna, the MIMO/diversity antenna has the ability to transmit or receive the 2.4 and 5.8 GHz signals simultaneously, without any external switching circuit between the module and the proposed antenna. [ABSTRACT FROM AUTHOR]

Operation of isolating switches and circuit breakers in fully enclosed gas insulated substations (GIS) produces very fast transient overvoltage (VFTO). According to IEC61321-1, VFTO contains four frequency components with frequencies ranging from 0.1 MHz to 100 MHz. Therefore, the VFTO measurement system needs to have good transient response and steady state response and puts high requirements on the measurement frequency band. As a measurement method that does not need to modified GIS, the differentiating-integrating measurement system has the characteristics of high frequency bandwidth and high voltage divider ratio. In this paper, the theoretical derivation and numerical calculation of the equivalent circuit of differentiating-integrating measurement are carried out, and the simulation of time domain, frequency domain and synthetic VFTO waveform as excitation source was constructed, and its performance is fully verified, which proves that this system can meet the needs of VFTO measurement. [ABSTRACT FROM AUTHOR]

We deal with quadratic stabilisation for switched systems which are composed of a finite set of affine subsystems, where both subsystem matrices and affine vectors in the vector fields are switched independently, and no single subsystem has desired quadratic stability. We show that if a convex combination of subsystem matrices is Hurwitz and another convex combination of affine vectors is zero, then we can design a state-dependent switching law and an output-dependent switching law such that the entire switched system is quadratically stable at the origin. If the convex combination of affine vectors is not zero, we discuss the quadratic stabilisation to a convergence set defined by the convex combination of subsystem matrices and that of affine vectors. We extend the discussion to switched uncertain affine systems with norm bounded uncertainties, and establish a quadratically stabilising state-dependent switching law based on an H ∞ norm condition for a combination of subsystems. Several numerical examples show effectiveness of the results. [ABSTRACT FROM AUTHOR]

This paper describes a new three-phase rectifier circuit using the partial switching strategy. A passive method to be composed of a diode rectifier circuit and an active method with the high-frequency switching were used for the circuit to convert from A.C. into D.C. mainly. However, the passive method and the active method had a problem of low power factor and low efficiency, each other. In contrast, the partial switching strategy realizes high efficiency and high power factor and low harmonics to a moderate degree. Therefore the single-phase partial switching voltage doubler rectifier circuit was applied to air conditioner. By the superior performance, most air conditioner adopts the partial switching strategy. In this paper, circuit configuration and a principle of operation and the experimental result of the three-phase partial switching rectifier circuit are reported. [ABSTRACT FROM AUTHOR]

In this paper, a novel adaptive dynamic sliding mode control(ADSMC) methodology is developed for space manipulator control systems with external disturbance. The proposed ADSMC approach can make the systems stable and accurately track the desired signals in the presence of external disturbances. Firstly, the simplified dynamic model of the manipulator is introduced. Then, the proposed adaptive dynamic sliding mode(ADSM) controller is given, which is proved to be able to guarantee high tracking accuracy via effectively estimating the disturbance boundary. Finally, experimental results show that the dynamic sliding mode controller proposed in this paper can not only track the desired trajectory, but also present strong robustness for external disturbance, meanwhile effectively reduce the chattering phenomenon generated by switching between different sliding mode surfaces. [ABSTRACT FROM AUTHOR]

The effect of weather conditions on the generation of harmonics in PV systems is investigated. A PV model, including the inverting stage, is considered. The output of the equivalent PV model is fed to the load via an inverter and transformer. The analysis is conducted by using a dataset of weather conditions in a North American city. Two converter techniques, which form the basis for the majority of converters, are used to validate the proposed approach: a square-wave inverter with 60 Hz switching, and pulse width modulation (PWM). Probability density functions and probability distribution models with best fit are determined as aids for improving the quality of the power generated for different range of converter values and the best is selected in this article. The long-term effects of weather conditions on harmonics produced by PV inverters are considered. The results show the variability in amplitude of each harmonic component, the boundaries of each harmonic component, and which harmonic magnitudes occur more frequently. The classic PV DC-AC conversion system has been modeled using MATLAB. The work is validated by using different ranges of dataset for two different converters and the results improved the importance of the proposed work. Also, the results agree with previous studies that have been carried with a different method which could be considered as another way of validation for the proposed work. Based on the generated harmonic variation cases, the appropriate parameter values for dynamic adaptive circuit switching of the filtering system and determining the capacity of the storage system could be determined. [ABSTRACT FROM AUTHOR]

A method of obtaining a multiplier cum divider by using (1) a pulse with integrated multiplier and (2) a time division multiplier is explained in this paper. Both the multipliers use a sawtooth wave as a reference clock. Including sawtooth wave generator, the circuit uses six op-amps, three analogue switches, and a peak detector. Verification of the feasibility of the circuit configuration is established by way of test results on a proto type. [ABSTRACT FROM AUTHOR]

A new topology of DC–DC boost converter using the voltage lift technique is introduced in this paper. Based on the conventional boost converter topology, the capacitor–inductor–capacitor (CLC) cells are constructed in the circuit to build multiple 'lift' in the structure and finally increase the voltage gain. Between each CLC cell, a diode is used to switch the operation of each cell. In the proposed topology, there are salient features including: (1) single switch in the circuit, (2) low switching voltage, (3) common ground between the source and the load, and (4) higher voltage gain than the traditional boost converter. The circuit with three lifts will be discussed in detail and to expand the utility of this design, N-lift topology using multiple CLC cells is also developed in this paper. Mathematical analysis and software-based simulation results illustrate features of this design. And, hardware-based experimental tests provide the potential value of this topology. Both the voltage gain and the power transferring efficiency are high, and these can demonstrate the value in both industrial and domestic utilities. [ABSTRACT FROM AUTHOR]

The paper describes an electrical analogue for aiding the solution of the classical transportation problem. It is based on the Simplex method of solution due to Dantzig. Two simple basic circuits, a feasibility circuit and a cost comparison circuit, are provided for each source and destination pair. Switching enables the feasible routes to be selected and then explored for comparative costs. The procedure is iterative. By not being self-optimizing but aiming to eliminate the routine hand calculation a flexible machine is provided with simple components. [ABSTRACT FROM AUTHOR]

Multi valley current mode pulse train (MVC-PT) control technology can completely eliminate the low-frequency oscillation phenomenon of DC-DC switching converters operated in continuous conduction mode (CCM). However, this method needs to increase the number of preset value to broaden the output power range, which will increase the complexity and cost of the controller, and reduce the robustness of the system. Meanwhile, the output voltage ripple is uncontrollable and varied with the changes of the load. In this paper, a novel sliding valley current mode PT (SVC-PT) control technique is proposed to solve the above-mentioned problem. The SVC-PT operating principle and the deficiency of MVC-PT method are analysed in details. The approximate discrete-time models of SVC-PT and MVC-PT controlled switching DC-DC converters are constructed and compared. The comparison results verify that the proposed control method can thoroughly lessen the restriction of the controller on the output power range. Moreover, the control circuit is simplified and the output voltage ripple can be controlled. Finally, the simulation and experimental results are present to prove the feasibility and scientific of SVC-PT control technology. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of full state constraints-based adaptive control for a class of switched nonlinear pure-feedback systems under arbitrary switchings. First, the switched pure-feedback system is transformed into a switched strict-feedback system with non-affine terms based on the mean value theorem. Then, by exploiting the common Lyapunov function (CLF) method, the Barrier Lyapunov function method and backstepping, state feedback controllers of individual subsystems and a common Barrier Lyapunov function (CBLF) are constructed, which guarantee that all signals in the closed-loop system are global uniformly bounded under arbitrary switchings, and full state constraints are not violated. Furthermore, the tracking error can converge to a bounded compact set. Two examples, which include a single-link robot as a practical example, are provided to demonstrate the effectiveness of the proposed design method. [ABSTRACT FROM AUTHOR]

A new resonant converter for high-input voltage and high-output current applications is presented to realize the advantages of low turn-on switching losses, low reverse recovery losses, and low voltage stress of power semiconductors. The series-connected half-bridge converter is used to lessen the voltage stress of power switches at V in/2. Therefore, power switches with low voltage stress and low turn-on resistance can be used to reduce the conduction losses on the primary side. For high-output current applications, two transformers series-connected on the primary side and parallel-connected on the secondary side are used to automatically balance the load current so that the low current stress of fast recovery diodes can be used at the output side. The operated switching frequency is controlled to be less than the series resonant frequency of the resonant converter. Therefore, power switches can be turned on at zero-voltage switching and the rectifier diodes can be turned off at zero-current switching. Experimental verifications with a laboratory prototype are provided to demonstrate the performance of the proposed converter. [ABSTRACT FROM AUTHOR]

In this paper, a zero-voltage-switching (ZVS) high step-up three level coupled inductor-based boost converter is proposed. Three-level structure of the proposed converter causes significant reduction of the switches and diodes voltage stress. The leakage inductance that is caused by coupled inductor leads to voltage ringing, the use of the active-clamp circuit in this structure not only eliminates the voltage ringing but also makes all switches turn on and off under ZVS condition that results in improving the efficiency. All the switches in the proposed converter will operate with an appropriate duty cycle for high step-up applications. The proposed converter features, operating principles and analysis are discussed in the paper and to verify the validity of theoretical analysis, the experimental results of a 200-W laboratory prototype with a 4-V input and 400-V output are presented. [ABSTRACT FROM AUTHOR]

A doubly Q-switched 1.06 μm pulsed laser using a novel tape casting YAG/Nd:YAG/YAG composite ceramic with a sandwich structure was demonstrated for the first time. Compared to purely acousto-optical (AO) Q-switching, this laser using an AO Q-switch and Cr4+:YAG saturable absorber simultaneously can generate shorter pulses. The pulsed laser performance was investigated at two modulated repetition rates of 10 and 20 kHz. [ABSTRACT FROM AUTHOR]

This paper considers the problem of anti-windup (AW) control for nonlinear singularly perturbed switched systems with actuator saturation. An AW controller consisting of a dynamic state feedback (DSF) controller and an AW compensator is firstly constructed. Then, two methods are proposed to determine the AW controller gain matrices by a common Lyapunov function. One of which assumes that the singular perturbation parameter ϵ is available and designs ϵ-dependent AW controller gains simultaneously. The other one, which considers the case that ϵ is unknown but sufficiently small, designs the ϵ-independent DSF controller gain matrices first and then designs the ϵ-independent AW compensator gain matrices. Both of the methods are reduced to solving convex optimisation problems and can achieve larger stability bound and basin of attraction than the existing results. Finally, examples are used to illustrate the feasibility and advantages of the proposed methods. [ABSTRACT FROM AUTHOR]

Between 1984 and 2014 over 3400 sell-side analysts changed the primary industry they followed. This article documents that analysts are more likely to change their industries when their absolute and relative forecasting accuracy in that industry is low and when the accuracy in the new industry is high. Analysts are more likely to switch industries at the beginning of their careers, after a recent change of an employing brokerage house, and if they have a history of switching industries before. Analysts are less likely to make a switch when their forecasting activity in the industry is high, when the industry is followed by many analysts and when they are employed by a top brokerage house. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of adaptive output feedback tracking for uncertain switched nonlinear systems, under arbitrary switching. First, an adaptive output feedback controller is designed, which ensures the boundedness of all the closed-loop signals. Then, a novel adaptivebased robust output feedback control is proposed to drive the tracking error to zero, in which the bound of disturbances is not required to be known in advance. Both control algorithms are based on the common Lyapunov function method, without any restrictions on dwell time. To evaluate the performance of the proposed output feedback control schemes, a numerical example is presented and discussed. [ABSTRACT FROM AUTHOR]

The formation of domain arrays and domain wall shape instability induced by ion beam irradiation have been studied in congruent lithium tantalate crystal covered by dielectric layer. The dependences of domain radii on exposure dose and array period were obtained. The domain wall shape instability effect (appearance of periodical oriented fingers) for doses above 20 pC was revealed. It was shown that dose increase led to increase of total length of the domain wall with fingers, while the finger number remained approximately constant. The observed results were explained by the kinetic approach based on analogy with first order phase transitions. [ABSTRACT FROM AUTHOR]

We present the results of experimental study of the local switching in single crystals of relaxor ferroelectric Ni-doped strontium barium niobate with various initial domain states using conductive tip of scanning probe microscope. We investigated the domain growth in as-grown domain structure and initial domain states created by: (i) scanning by biased tip, (ii) in-field cooling, and (iii) scanning by electron beam. The dependences of effective domain radius on the voltage and pulse duration were derived. The shape factor, domain wall mobility, and start voltage were revealed. The obtained results can be used for the domain engineering in ferroelectrics. [ABSTRACT FROM AUTHOR]

This paper proposes a novel switching method with the neutral-point voltage control in a single-phase neutral-point-clamped three-level inverter (SP-NPCI) used in photovoltaic systems. A proposed novel switching method for the SP-NPCI improves the efficiency. The main concept is to fix the switching state of one leg. As a result, the switching loss decreases and the total efficiency is improved. In addition, it enables the maximum power-point-tracking operation to be performed by applying the proposed neutral-point voltage control algorithm. This control is implemented by modifying the reference signal. Simulation and experimental results provide verification of the performance of a novel switching method with the neutral-point voltage control. [ABSTRACT FROM AUTHOR]

At present, the detection technology of non-contact ultrasonic and transient earth voltage is widely used in the partial discharge detection of switchgear. The test result is directly related to the diagnosis and evaluation of the insulation state of electrical equipment. In order to characterize the accuracy of PD detection, it is proposed to use the terminal linearity calculation to analyze the linearity of the PD detector in the frequency band. Finally, the linearity test of the UltraTEV Plus PD detector is carried out by setting up a dedicated performance test platform in the laboratory, which verifies the effectiveness of the method and reflects the minimum linearity near the resonant frequency. [ABSTRACT FROM AUTHOR]

A blue-phase liquid crystal display (BPLCD) with single–penetration (S-P) electrodes is proposed to reduce the operating voltage. X-shape inclined-electric field is induced by the S-P electrodes with 2 ~ 3 μm height, which can lower the operating voltage by ~45%, and improve the transmittance compared with BPLCD with conventional in-plane electrodes. Moreover, the wide viewing angle and very small image distortion index can be obtained in this structure with a half-wave biaxial film. The proposed structure shows simple etching control and easy one-drop filling process of blue-phase liquid crystal compared with dual-convex-penetration electrodes. [ABSTRACT FROM AUTHOR]

This paper reports development of a highly sensitive pulsed eddy current (PEC) instrument based on metal-oxide-semiconductor field-effect transistor (MOSFET) switching logic capable of driving high current with varying rise time for testing thick metallic materials. A high dynamic range 24-bit analogue-to-digital converter card is used to effectively differentiate PEC signals from flaw and flaw-free regions. A PEC probe having a cylindrical coil exciter and a giant magneto resistance sensor receiver is used. The developed PEC instrument and probe have reliably detected sub-surface flaws located at 6.0 mm below the surface of an 8.0 mm thick stainless steel plate with a signal-to-noise of 15 dB. [ABSTRACT FROM PUBLISHER]

In this paper, a soft switching DC–DC converter is presented for a hybrid energy storage system (HESS) in an electric vehicle (EV), using fixed boundary layer sliding mode control (FBLSMC) and variable switching frequency modulation. This strategy is aimed at improvement of the transient performance, energy transfer efficiency and system robustness for the HESS which is composed of a battery, an ultracapacitor (UC) and a bidirectional DC–DC converter. The state-space model of such DC–DC converter is firstly established involving all operating modes and system uncertainties. The FBLSMC scheme is proposed for the satisfactory voltage/current tracking despite system uncertainties. It can guarantee the system robustness and avoid the chattering existing in conventional sliding mode control (CSMC). In order to ensure the soft switching under transient load variations, a variable switching frequency modulation method is introduced into the controller. Finally, experimental results confirm that (1) within the full-load range the efficiency of the DC–DC converter with variable switching frequency is ∼96% in contrast to 90% efficiency at hard switching, and (2) the energy delivered by the UC follows the reference closely for EVs. [ABSTRACT FROM AUTHOR]

This paper explains the state of art of switched flux wound-field machines (SFWFMs). The main advantage of these SFWFMs when compared with induction machines, synchronous machines, direct current machines, etc. is that all the active parts such that armature coil and field excitation coil are located on the stator while the rotor part consists of only iron material without windings. This makes the machine more robust, simple structure, and more suitable to be used for high-speed applications, compared to induction machine which has low mechanical strength, less torque desnity, and low power factor. Theories, numerical and technical literature of different SFWFM are described and analysed. Merits and demerits of different SFWFM structure are discussed. This paper categorized SFWFM topologies on the basis of their structure, flux linkage, cogging torque, average torque, and efficiency. [ABSTRACT FROM PUBLISHER]