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Torsional vibration signal analysis is promising for diagnosing gear faults in planetary gearboxes. However, early-stage fault signatures are relatively-weak and may be ignored or wrongly identified in conventional demodulation analysis, especially under time-varying speed conditions. Two main contributions are made in this paper. Firstly, an analytical model of planetary gearbox torsional vibration signal is established, by jointly considering the gear mesh vibration, torsional resonance, and other time-invariant components. The gear fault characteristics under time-varying speeds are accordingly revealed explicitly. Furthermore, inspired by the unique time-frequency structure of the torsional vibration signal, the multi-band torsional vibration amplitude demodulation method is proposed for gear fault feature extraction. The proposed method combines the gear fault features in multiple characteristic frequency bands in torsional vibration signal, so that the influences from adjacent carrier frequencies, independent frequency harmonics and random noises can be eliminated in amplitude demodulation. As a result, the obtained amplitude demodulated order spectrum outperforms conventional envelope order spectrum and narrow-band amplitude demodulated order spectrum in revealing relatively weak gear fault features. Both numerical simulation and laboratory experiments are conducted, to demonstrate the correctness of the established analytical model and the advantages of the proposed multi-band torsional vibration amplitude demodulation method. Localized fault on the sun, planet and ring gears are successfully diagnosed.

Over the past two decades, the prominence of physical attacks on electronic devices, designed to extract confidential information, has surged. These attacks exploit the inherent physical characteristics of integrated circuits (ICs), leading to information leakage. While several cutting-edge countermeasures have been developed to thwart attempts at obtaining sensitive data, the potential of shielding as a defensive mechanism has not been comprehensively explored within the realm of ICs. Shielding, with its capabilities encompassing the reduction of electromagnetic (EM) radiation leakage, detection of penetration attempts, and the obfuscation of adversaries’ measurement efforts, presents an intriguing avenue for safeguarding information. Remarkably, the investigation into the efficacy of shielding in minimizing EM radiation leakage and consequently curtailing information leakage has been somewhat limited in the context of ICs. This limitation extends to various aspects, including the topological configuration of shields, the development of a comprehensive analytical model for leakage assessment, and the simulation capacity prior to the silicon fabrication stage. Previous state-of-the-art (SOTA) reports have primarily concentrated on the prevention of probing or penetration of shielding mechanisms. In our research, we contribute a fully refined analytical model tailored for IC shielding, capable of accurately estimating fields in presence of shields and evaluating security against a spectrum of IC hardware (HW) attacks. Importantly, we introduce a simulation methodology employing CAD tools, IC Process Design Kit (PDK), and Ansys HFSS to evaluate shielding performance within layouts directly imported from a commercial CAD and IC PDKs, following the integration of full-chip tools.

Silicon carbide three-level active neutral point clamped converters (SiC 3L-ANPC) have emerged as promising solutions for medium-voltage high-capacity applications. However, compared to traditional two-level converters, they exhibit a relatively higher presence of stray parameters. The combined impact of high $\text{d}v/\text{d}t$ , $\text{d}i/\text{d}t$ and multiple stray parameters during the switching transient process can lead to non-ideal behaviors, including voltage and current overshoots, along with oscillations. These issues contribute to increased switching losses and limitations in power handling. Therefore, a thorough evaluation of the switching transient process becomes imperative to ensure the proper design and protection of 3L-ANPC converters. An analytical model is proposed in this article that accurately characterizes the switching transient process of SiC 3L-ANPC converters. The model is developed based on a comprehensive analysis of the switching transient mechanism. By focusing on specific pivotal moments within the transient process, the model significantly reduces computational time. Moreover, these distinct moments carry explicit physical significance and possess universal applicability. Experimental results validate the effectiveness of the proposed model, showcasing a maximum calculation error of less than 6% for transient overshoots. The insights presented in this article provide guidance for designing circuit parameters in SiC 3L-ANPC converters, aiding in the mitigation of overvoltage issues.

In this work, we present the design and modeling of a new type of choke horn antenna. It incorporates a rectangular waveguide and a rectangular choke acting as a parasitic element. The four-sided geometry of the antenna is applicable to systems that utilize rectangular waveguides. Also, it can overcome the need for rectangular-to-circular transition of transmission line or mode conversion. The main objective of this paper is to develop a model that calculates the far field radiation characteristics of the proposed antenna (analytical part) and to incorporate a finite element method (FEM) solver that adds to the theoretical solution (empirical part), which finally leads to obtaining a hybrid model. The omnidirectional radiation property of the choke is demonstrated, which gives an insight into the influence of this parasitic element on the total radiated power. The same observations made on the rectangular choke can be translated to the circular choke as well. At an operating frequency of 2.45 GHz, the design is numerically and experimentally validated. Also, the demonstrated hybrid model can leverage the integration of supervised machine learning (ML) models by exporting radiation variables such as gain and half-power beamwidth (HPBW) and performing predictions based on the training data from the model. Therefore, we incorporate gradient boosting and neural network ML algorithms, which are tailored to the desired radiation pattern parameters.

This paper examines and compares the performance characteristics of inner and outer rotor surface permanent magnet (SPM) machines. Notably, this research distinguishes itself through a rigorous methodology that carefully selects an optimization dataset rather than relying on arbitrary data. Consequently, this methodology has yielded valuable insights in two significant aspects: 1) The trends of key design parameters for both inner and outer rotor types, such as split ratio, aspect ratio, and magnet-gap ratio, are revealed using the optimization dataset. 2) The torque-to-weight ratio values between the inner and outer rotor types are investigated from various perspectives. Through this analysis, it becomes numerically evident that a significant advantage can be obtained using the outer rotor type compared to the inner rotor type. Overall, this study provides valuable insights for researchers, particularly those involved in the initial design stage of SPM machines for both rotor types.

Fast and accurate switching loss models that can be used for different devices are crucial for optimization-based converter design. This paper proposes a novel data sheet based, fully analytical loss model for a SiC MOSFET and Schottky diode half-bridge including parasitics. In the model, nonlinear device characteristics are approximated by multi-step piecewise constants. Furthermore, a small number of assumptions are used to derive and to solve the approximated nonlinear differential equations for obtaining the switching losses. To evaluate the model, a new accuracy measure is proposed for a fair accuracy comparison with existing models. The proposed model is also comprehensively verified by double pulse tests using 5 SiC MOSFET (with different structures) and Schottky diode pairs from different manufacturers. The proposed fully analytical model exhibits on average the best accuracy with a high computational efficiency (less than 1 ms per operating point) compared to state-of-the-art analytical switching loss models, as validated by using both data sheet information and measured device characteristics.

The permanent magnet synchronous motors are widely used for the propulsion of electric vehicles. These motors have good performance, but result expensive because the permanent magnets installed on their rotor contain rare earths. A promising solution to reduce the cost of the motors is to replace the magnets with an excitation coil, which requires to transfer its own supply power to the rotor of the motor. The power transfer is performed by means of a rotary transformer. This paper develops a simplified steady state model of the rotary transformer which allows to asses with good accuracy the position of some points in the waveforms of the currents in the primary and secondary coils of the transformer and in the excitation coil. The inputs of the model are the inductive parameters of the transformer itself and the electrical parameters of the power switches that compose the inverter that supplies the primary coil and of the diodes that form the rectifier connected to the secondary coil. The accuracy of the analytical expressions that give the position of the points on the current waveforms is verified by comparison with the results obtained from simulations and with the current waveforms acquired from a prototypal transformer available in the lab.

This paper proposes analytical modeling and design of a 27.12 MHz single-switch dc-dc converter with galvanic isolation using a PCB transformer. The ODE-based analytical approach provides a more accurate circuit design by considering the high-order harmonics and non-ideal components such as the diode capacitances. The proposed dimensionless mathematical model simplifies the design of the desired circuit model and requires less tuning procedure. In addition, the effective analytical model offers the design curves to obtain the optimized circuit parameters at any duty ratio. Meanwhile, the multilayer planar PCB transformer is designed to achieve the isolation and high power density for the high-frequency dc-dc converter. Based on Neumann’s formula, the analytical model of the PCB transformer is proposed to calculate the inductances for the spiral structure accurately in the high-frequency conditions. As a result, the computational burden for calculating the coil inductances is alleviated using the proposed method. The simulation and experimental results using a 3W converter prototype verify the effectiveness and feasibility of the analytical modeling and design of the proposed converter.

Rotary electromagnetic fault current limiter (FCL) is an emerging technology for limiting fault currents in the power network. The device consists of two movable air-core spherical reactor rings (i.e., inner and outer rings). The movable feature allows the reactor rings to rotate, and form a proper mutual positional displacement. This can limit the fault current since the effective inductance of the device is dependent to the mutual angular position of the reactor rings. Due to the unconventional structure, to this date, the design process has solely been based on finite element (FE) method. This paper aims to analytically validate the theory and the overall functionality of the device in both the steady state and transient regime. For this propose, the resistance and the inductance of the device are first computed at normal operating condition using the basic theory of engineering electromagnetics. Next, performance characteristics such as electromagnetic torque, rotational displacement of the reactors, effective inductance of the device, and the network current are calculated at the faulty condition. For verification purposes, analytical results are compared with via FE simulation and experimental test.

In this paper, a new accurate and comprehensive analytical model of harmonic and interharmonic distortion produced by a single-phase AC/DC diode bridge rectifier (DBR) is presented. Its main and new characteristic is the ability to consider the presence of interharmonics in addition to harmonics in the voltage at the terminals of DBR due to the background distortion. Analytical expressions able to predict DC voltage and AC current either in time or frequency domains are obtained. Several numerical and experimental tests have been performed showing very accurate results. The proposed model presents all the advantages of analytical models (e.g., fastness); therefore, it can be easily integrated with iterative harmonic and interharmonic analysis procedures. Subsequent applications are the possibility to perform parametric analyses and probabilistic studies, to derive harmonically and interharmonically coupled admittance matrices, to help in introducing standard limits for interharmonics.

This paper presents an approach to evaluate capacitance developed by perforated membrane of RF MEMS switch with high accuracy. An analytical model is developed for both upstate and downstate of switch by including parasitic and fringing field capacitance in parallel plate capacitance model. The proposed analytical model includes the ligament efficiency term directly in the formula which reduce the efforts to calculate it individually for various perforation sizes. The capacitance analysis has been carried out by varying the physical parameters to optimize the switch dimensions and these analytical results are compared with the simulation results carried out by 3D FEM tool COMSOL multiphysics for validation. The proposed analytical model results are then compared with benchmark models to understand the efficiency of proposed model in estimating the up and downstate capacitances. The proposed analytical model proved to be good with less error percentage of 2.13% at upstate and 2.59% at downstate whereas the other benchmark models gives greater than 5% error. The switch is then fabricated using 4-mask surface micromachining process and experimental evaluation of capacitance at both upstate and downstate is carried out by DC probe station. Experimentally, the upstate capacitance is obtained as 37.4 fF and downstate as 2.43 pF and the analytical models exhibited low error percentage of 3.95% at upstate and 2.05% at downstate condition for µ = 0.5.

In this work, for the first time, we have investigated an analytical model for β-MIS-(AlGa)2O3/Ga2O3 ion-sensitive FET by using commercial Silvaco and MATLAB tools for non-ideality behavior around the isoelectric point. Gouy-Chapman-Stern theory is used to analyze the electrical double layer with the electrolyte. Al2O3 is used as a dielectric between (AlGa)2O3 and electrolyte. The pH sensor detects the variation in hydrogen ion concentration in the aqueous solution. Different electrolyte concentrations (1 mM, 0.01 M, 0.1 M) are used in aqueous solution to find sensitive parameters such as surface potential, charge density, Alpha, βint, Cdiff and CDL for different pH values. Changes in surface potential and other sensitive parameters affect the intensity of 2DEG at the interface of (AlGa)2O3 and Ga2O3 in β-MIS-(AlGa)2O3/Ga2O3 HEMT. The behavior of pH- sensitive parameters are also discussed before and after the isoelectric point. Variation in electrolyte concentration shows that lower electrolyte concentration has high sensitivity. Effects of variation of pH on potential, H+ and OH− concentration with bulk distance have also been discussed. Transfer characteristics, threshold voltage, ION/IOFF of β-MIS-(AlGa)2O3/Ga2O3 HEMT have been investigated for different pH values. Threshold voltage increases with pH when pH moves from acidic to basic medium. [ABSTRACT FROM AUTHOR]

The objective of this article isto developa comprehensive mathematical model of a three-phase induction motor to facilitate stator interturn (SIT) fault related study. A detailed analytical model that includes accurate inductance modeling considering rotor slot harmonics (RSH) under healthy as well as SIT faults is described. The proposed model is developed analytically in a step-by-step manner incorporating the features of RSH. A detailed but simplified analysis considering both magnetomotive force harmonics and air-gap flux harmonics has been presented. An asymmetric model is proposed, including SIT faults, in a single phase of the induction motor in the next stage of the modeling. The effect of saturation has also been considered in the model. The proposed model is validated by comparing the simulation results in transient, steady state, and frequency domain with the experimental results. Comparison shows a high degree of correlation with the results of the actual motor. The contributions of this work are justified by comparing the proposed model with the existing models. This article also shows that a frequency signature related to RSH present in the line current is capable of characterizing the SIT faults. [ABSTRACT FROM AUTHOR]

This article presents a low detent force double-sided permanent-magnet synchronous linear motor (DS-PMSLM), which contains two flat-type stators and a mover. The mover is constituted of a fiberglass support plate and Halbach array permanent magnets attached on both surfaces of this plate, which provides a large thrust force and low mover mass for high dynamic response. For the sake of reducing the thrust ripple, a modulation method of the cogging and end forces is proposed based on the destructive interference. The even-order harmonics in cogging and end forces are reduced by adjusting the width of the side slots and the lengths of end teeth, respectively. In order to reduce the odd-order harmonics of the detent force, the cogging force and end force are modulated to reverse phases and identical amplitudes by changing the equivalent lengths of four end teeth. An integrated subdomain analytical model considering the cogging and end effects is built to optimize five structural parameters of the stators for low detent force. Finally, the prototype and testing platforms are set up and the experimental results validate that the proposed DS-PMSLM can achieve a low thrust ripple of less than 1.5 $ \%$. [ABSTRACT FROM AUTHOR]

Surface-mounted permanent magnet (SPM) machines with skewed slots as vehicle drives are widely used. Due to skewed slots, electromagnetic characteristics are modulated by the skew effect. To analyze the skew effect, Maxwell’s equations-based 3-D analytical model is proposed. Based on differences in 3-D air-gap flux density distribution, the mechanism by which the skew effect modulates cogging torque, flux linkage, and back electromotive force (EMF) is investigated. The effectiveness of the theory about the skew effect is verified by both the finite element method (FEM) and the experimental result. [ABSTRACT FROM AUTHOR]

The paper is aimed at an investigation of the features of a tubular-linear synchronous quasi-Halbach machine (T-LSM) where the radially-magnetized PMs are substituted by four equal segments with parallel magnetization. This substitution is done in an attempt to improve the machine cost-effectiveness which makes it a viable candidate to equip free-piston engine-based series hybrid propulsion systems. The study is initiated by an analytical formulation of the air gap flux density considering (i) the case of the conventional quasi-Halbach T-LSM and (ii) the case of the segmented pole one. The comparison between the two T-LSMs is extended to a 3D finite element analysis (FEA)-based investigation of their no- and on-load features. Following the prototyping of the quasi-Halbach T-LSM with segmented poles, selected features predicted by 3D FEA are experimentally-validated. It is shown that while the PM segmentation slightly affects the machine back-EMF and cogging force, it has a remarkable fallout on its force production capability which makes it necessary the assessment of the cost-performance trade-off.

The development of the Internet of Things (IoT) has shown significant contributions to many application areas, such as smart cities, smart homes, and smart farming, including aquarium control systems. Important things in an aquarium system are the level of ammonia in the water and the temperature of the water. Other research proposes several systems to make the aquarium control system robust for the aquarium monitoring and control system. However, those systems have weaknesses; namely, the user must actively access information to the server. This paper proposes a robust aquarium control system using the decision tree regression (DTR) algorithm. The development of this system was to overcome the problem of aquarium control by remote users. An accurate and real-time system is needed to monitor the aquarium so that it does not reach dangerous and critical points, such as in the case of an increase in water temperature. We did tests by developing an aquarium system connected to a server and an application that acts as a controller. Our measurements check the delay of sending data from the sensor to the server, process delay, actuator delay, user delay, and delay in reaching the aquarium’s critical point. The measurement of the system’s robustness is by calculating the probability of the information arrival to the user in the period of the critical point compared to the time needed to reach the critical point. Furthermore, we also made an analytical model based on the probability density function of the delay covered in this system. Analytically and experimentally, we show that the system can meet the needs of aquarium monitoring and control in an IoT-based environment.

Prefetching offers the potential to significantly improve performance by speculatively loading application data so that it is available before it is needed. By their very nature, prefetching techniques are application behavior dependant. This implies that no universal prefetching solution exists. A combination of prefetching strategies need to be used to target a diverse set of applications. In this work, we develop the first comprehensive mathematical framework that allows a designer to better understand the prefetching opportunities of an application. We first use dynamic analysis to study the memory access behavior of an application and measure a series of metrics to both identify the optimized schedule, and estimate its achievable performance. To validate our model, we implement and evaluate three different prefetching strategies: helper threads, software prefetching and FPGA prefetching. We show that, for each individual scenario, our framework correctly generates the optimized schedule of prefetches and predicts the performance improvement with an accuracy of more than 95%. Using our framework, developers can choose the best prefetching strategy and parameters for their specific workload and use case.

The incessantly increasing demand for highly dense storage medium in this era of big-data has led to the development of 3D NAND Flash memories. 3D NAND Flash based SSDs have revolutionized edge storage and become an integral part of the data warehouses and the cloud storage systems. The conventional 3D NAND flash memory with greater than hundred stacked word-line (WL) layers suffer from channel tapering and non-uniformity in the threshold voltage of cells in different WL layers which necessitates the use of different programming voltages for different WL layers and a complex error-correction circuitry. A non-uniform vertical (Gaussian) channel doping profile alleviates the threshold voltage non-uniformity and leads to a significant reduction in the complexity of the error-correction circuitry and a simple (uniform) programming scheme for all WLs. Although behavioral models have been proposed to utilize 3D NAND flash memory for circuit and system-level applications, an analytical model is important to understand the intricate details of the device physics and propose design guidelines for efficient cell design. To this end, in this paper, for the first time, we have proposed an analytical model for the characteristic length, surface potential and inner potential of the Macaroni-body 3D NAND flash cell with vertical Gaussian doping profile. A strong agreement between the analytical model and the TCAD simulations for different gate lengths (down to 25 nm), inner and outer radius, channel and oxide thickness of the 3D NAND flash cell validates the efficacy of the developed model.

This paper proposes a method to develop an analytical model and/or numerical resolution of the quality factor of quarter-wavelength n-section coaxial stepped impedance resonators (SIRs). The topology is based on cascaded coaxial sections nested within each other. Thanks to the SIR effect, this type of geometrical arrangement offers practical degrees of freedom to modulate the size of the resonator in both longitudinal and transverse dimensions. Moreover, in an air-filled configuration, it provides interesting quality factor, although this depends on its shape factor at any given frequency. In this paper, we show the added value of using an analytical model or numerical resolution for the quality factor, to be able to optimize the topology. To demonstrate the advantages of this model and the numerical method, comparisons of two- and three-section coaxial SIRs at two different frequencies are proposed and discussed. To validate the analytical model and numerical resolution, the values are compared with ones obtained in eigenmodes ANSYS HFSS with electromagnetic simulation tool.

This work presents a novel abc-based model applicable to surface-mounted permanent magnet AC (SM-PMAC) machines with sinusoidal and non-sinusoidal back-electromotive force (back-emf). It is capable of predicting the electromagnetic performance metrics such as torque waveforms, machine inductances, flux linkages and back-emf. The closed form expressions of the model, which can be evaluated with a high computational efficiency, are derived from basic geometric and winding parameters. Validation of the model is carried out numerically and experimentally with a very good match in results. Finally, the computational efficiency of the model is highlighted by considering a multi-objective evolutionary optimization design of SM-PMAC machine with a relatively large number of design parameters, where results are presented and discussed.

Torque ripples cause acoustic noise, fluctuation in speed, vibration, and reduce lifetime of the motor. The double salient structure of Flux Switching Motor (FSM) has a high air-gap permeance variation that produces high torque ripples. This paper presents an analytical model to reduce air-gap permeance variation and torque ripples of the proposed octane modular stator 8slots-6poles single-phase Electrically Excited (EE) FSM. Furthermore, the rotor pole shaping technique is used to minimize the air-gap permeance variation and therefore, torque ripples of the proposed design are reduced. The electromagnetic performance of EEFSM is analyzed via the Finite Element Analysis (FEA) method. For the proposed design magnetic flux harmonics are reduced by 71% and back-EMF harmonics are suppressed by 48.5%. Torque ripples of the proposed EEFSM are reduced by 20%, cogging torque is diminished by 42.7% and average torque is enhanced by 5.8%. Finally, the prototype is fabricated and tested experimentally. Calculated values and experimental results are in good agreement and the difference is 3.5%-5%.

Brushless doubly fed reluctance generator (BDFRG) provides a good substitute for the doubly fed induction generator for the wind energy applications due to the nonexistence of the slip rings. Real time modelling of the BDFRG is a challenge due to the high leakage inductance of the stator windings. While the magnetic saturation of the iron parts affects the inductances values, therefore studying the effect of magnetic saturation on the BDFRG performance is important. In this paper, a BDFRG model including iron saturation is built. The finite element (FE) analysis using FEMM software is used to generate the relationship between the generator currents and the inductances, the generated data are recorded in a lookup table. A Simulink model of the BDFRG driven wind turbine, with two cases of constant and variable inductances, are developed and verified with FE analyses at range of wind speeds above and below the synchronous speed. The lookup table proposes is verified using finite element analysis at different modes of operation of wind speed and compared with the constant inductance model to show the importance of saturation inclusion in the generator model for accurate generator modelling representation.

Crosstalk fault avoidance codings (CACs) is extensively utilized. Among promising existing CACs methods, the one which has attracted much attention due to worst-case crosstalk fault delay prevention is One-Lambda Codes (OLCs). Unfortunately, two challenging issues are coming their way: 1- Exact model is required to estimate an exact delay of wires to provide accurate OLCs. 2- OLCs codec suffers from high energy consumption and overhead caused by critical path and area occupation. In this research, an accurate probability model is introduced to overcome these problems by Accurate Crosstalk Model (ACM) prediction. If crosstalk faults show up, ACM can estimate the communication channels delay by using 5-wire delay. It can help to improve the recently proposed analytical model that suffers from a lack of accuracy. Next, we present an accurate UP-Down OLC (UD-OLC) based on the numeral system and can eliminate transition patterns, including OLC-induced patterns, completely. In comparison with the other state-of-the-art OLCs, the UD-OLC mapping algorithm effectively alleviates wires energy consumption and average latency by up to 61% and 27%. Experimental results also reveal that this an overhead efficient numeral-based method benefits from the overhead degradation in terms of dynamic power, area, and critical path by up to 52%, 45%, and 20%, respectively when we compared it to the others.

This article describes a novel analytical methodology for eddy current losses simulation in the windings of permanent magnet synchronous machines. The methodology is based on subdomain modeling technique in conjunction with solving of ordinary differential equations system. The main advantage of the proposed method is high accuracy and significant reduction of simulation time in comparison with finite-element modeling (FEM) technique that is frequently used for eddy current loss modeling. The proposed model allows fast and accurate evaluation of proximity and skin effect in conductors in time domain for an arbitrary current waveform and machine duty cycle. The main difference from previously presented analytical methods is the possibility to evaluate losses for a wider range of conductors geometries, regardless their shape, dimensions, location in the stator slots, and rotor speed. The main contribution and novelty of the proposed analytical approach is simultaneous implementation of subdomain modeling technique and strands segmentation concept followed by the eddy current effect representation through the equivalent circuit. This approach allows reducing the computational time while keeping the accuracy close to the FEM result. The proposed model was compared to FEM, using different types and sizes of conductors and also validated experimentally. [ABSTRACT FROM AUTHOR]

With the emergence of electric vehicles and electric aircraft technologies, lightweight motors have become a requirement. Conventional motors are generally made up of coils, permanent magnets, heavy iron stators, and rotor cores. This article presents complete analytical modeling and design of a novel coreless multi-phase magnetic resonant motor (MMRM), conceptualized through the approach of magnetic resonance coupling. The removal of magnetic iron cores drastically reduces the weight of the resulting motor. The stator and rotor cores of the motor are made of reinforced plastic fibers and can be 3-D printed. Unrelated to the general operating principle of the existing conventional electric motors, resonant wireless power transfer (WPT) is the key feature of these motors. All the essential machine characteristics, such as self-inductance, mutual inductance, torque, and frequency domains, are fully developed. The mathematical modeling of the machine’s physical phenomena is linked to its operation by simulation. This article shows the design concept and discusses the simulation procedure used to verify the developed analytical model through a finite-element analysis (FEA) from the established modeling topology equivalent to the proposed configuration motor model. Although the design is straightforward, an accurate analytical modeling and analysis are significant challenges to consider. [ABSTRACT FROM AUTHOR]

In amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs), the conduction mechanism of percolation and trap-limited conduction prevails within the limits of gate voltage. In these limits, the gate voltage-dependent mobility follows a power law. The temperature dependence of gate-functioned mobility is modeled by introducing very few empirical parameters (P and $\gamma $), where P follows the Arrhenius equation and $\gamma $ is found to be constant for varying temperature ranges. The proposed model effectively incorporates the combined effects of mobility as a function of temperature and gate voltages of the device using a single formulation for accurate thermal characterization. This model reproduces the measured characteristics of oxide TFT for a wide temperature range with an average error less than 2.5%. The model is implemented in Verilog-A to facilitate circuit simulations. Further, an 11-stage Ring-Oscillator is simulated with the proposed model. These results are compared with the measured circuit response under similar testing conditions to validate the model accuracy in the complete region of operation over a wide range of temperature variations. These simulation results show a good agreement with measured results within 8% accuracy, reinforcing the model validation. [ABSTRACT FROM AUTHOR]

This article develops a nonlinear analytical model (NAM) for predicting the magnet loss of surface-mounted permanent-magnet (PM) motors considering nonlinearity effect and slotting effect. The analytical expression of vector magnetic potential in the PM region is derived from Hague’s equation for slotless air-gap, and then, it is extended for slotted air-gap based on the conformal mapping method. The PMs, iron nonlinearity, and winding current contributing to the eddy current are all represented by equivalent current in the analytical model. The key of the proposed model is to solve the equivalent current of iron nonlinearity from the improved magnetic circuit model (IMCM) of iron region, where the air flux source is proposed to replace the air reluctance. It is found that the iron saturation can decrease the amplitude of flux density and therefore reduce the magnet loss. Based on the NAM, the magnet loss can be obtained with high accuracy and high efficiency, which is a powerful tool for the optimization of magnet loss in the motor design. The effectiveness of the proposed model is verified by the finite-element method. [ABSTRACT FROM AUTHOR]

This work aims at proposing an analytical model for the variability of the threshold voltage and drain current in junctionless nanowire transistors. The model is continuous in all operation regions and has been validated through Monte Carlo simulations using a physically based drain current model and 3-D numerical simulations. A discussion about the influences of each variability source based on the proposed model is carried out. Finally, the modeled results are compared to the experimental data for a fully physical validation. [ABSTRACT FROM AUTHOR]

This article analyzed and compared the complex permeance model (CPM) and nonlinear analytical model (NAM) for surface-mounted permanent magnet (SPM) motor using a voltage source inverter (VSI). For linear CPM, the slotting effect is represented using the improved complex permeance function that describes the real slot shape rather than infinitely deep slot. NAM is extended from CPM and it replaces the magnetic potential drop of stator iron by the equivalent virtual current in the slot-opening and tooth-tip to account for the nonlinearity effect. The nonlinear inductance of SPM motor including the main phase inductance, slot leakage inductance, tooth-tip leakage inductance, and end winding leakage inductance is calculated using the frozen permeability method, which is the key to solve the electric circuit with VSI. The instantaneous back electromotive force (EMF) is calculated from the nonlinear back EMF coefficient and the back EMF neglecting iron nonlinearity. The electromagnetic torque obtained from motor model is used in the mechanical model and then the rotational speed and rotor position are obtained for the electric circuit model. Hence, the iterative solving process for the motor system is established to calculate the transient performance of SPM motor using VSI. Compared with CPM, NAM can greatly improve the calculation accuracy, which is also validated by both finite-element model and experiment. Besides, the proposed NAM is computationally efficient, which is useful for both motor design and motor control. [ABSTRACT FROM AUTHOR]

To facilitate the active magnetic bearing (AMB) design and analysis, an accurate and fast model that considers both rotor eccentricity and the saturation effect is necessary. In this article, a novel hybrid analytical model (HAM) for effective calculation of the magnetic field of the AMB is proposed. Eccentricity and local saturation are considered in the proposed HAM. In the proposed HAM, the stator and rotor are modeled by elementary subdomains (ESDs) and the air-gap is modeled by magnetic equivalent circuit (MEC). Direct coupling between the solutions in the ESD regions with MEC completes the whole model matrices. Compared to the existing literature, the proposed model considers both the rotor eccentricity and material nonlinearity. The effectiveness and accuracy of the proposed HAM are validated by both the finite element model and experimental results. The results show that the proposed HAM can accurately predict the magnetic quantities of the AMB. [ABSTRACT FROM AUTHOR]

A novel cage-secondary permanent magnet (PM) linear eddy current brake (ECB) with wide speed range and its analytical model are presented in this article. Differ from the existed PM ECB, the proposed ECB owns the variable parameters cage-secondary structure. This unique secondary structure can keep braking force at a large constant value from high speed to low speed by changing the secondary parameters in different speed ranges. First, both the structure and working principle of the proposed ECB are given. Then, a new analytical model combined with multilayer theory is proposed, where the saturation of secondary iron teeth and the end effect are considered. Based on the magnetic field distribution result, the characteristics of proposed ECB are analyzed. Third, the accuracy and validity of the analysis results are verified by the finite-element method and prototype experiments. Moreover, based on the genetic algorithm, the optimal secondary parameters are obtained with the objective of maximum braking force at each speed. [ABSTRACT FROM AUTHOR]

It is recognized that the rotor with shielding cylinder (SC) is one of the effective measures to restrain the rotor eddy current loss (RECL) for high-speed surface-mounted permanent magnet synchronous motors (PMSMs). At present, the RECL of PMSMs with multilayer composite rotor structure is mainly analyzed by the finite element method (FEM), which has obvious shortcomings in time-consumption and the mesh generation of thin SC. In this paper, a multi-layer subdomain analytical model for calculating the RECL of high-speed PMSMs with both non-ferromagnetic retaining sleeve and SC is proposed by taking the effects of eddy current reaction, stator slotting and current harmonics into account. Moreover, the 3-D distribution coefficient of eddy current in the SC is derived by the equivalent impedance method and the effects of temperature on the conductivity of the SC and RECL are obtained through equivalent thermal network (ETN) model. Based on the analytical model, the SC parameters are calculated to obtain the variation ranges when the RECL is minimum. Finally, the C-shape core experiment was built up to verify the correctness of the multilayer analytical model under different shielding layer conductivities and thicknesses. [ABSTRACT FROM AUTHOR]

We report GaN-based vertical Schottky barrier diodes (SBDs) with embedded floating islands (FIs). The incorporation of FI structure can break the theoretical limit of unipolar vertical GaN devices by homogenizing the electric field distribution within the drift layer. To facilitate comprehensive understanding and structural design of FI SBDs, analytical models for both conducting state and blocking state of GaN FI SBDs are established and verified by TCAD simulation. Parametric optimization for the reverse characteristics of GaN FI SBDs is also carried out systematically. We found that the doping concentration, height of p-GaN FIs, and spacing between adjacent p-GaN FIs are closely associated with the electric field distribution and the reverse breakdown characteristics of vertical FI SBDs. An optimum Baliga’s figure of merit (FOM) of 4.98 GW/cm2 can be achieved, which features a 79.14% enhancement compared with the conventional SBD. The results can provide systematic design guidelines for GaN vertical power electronic systems toward high-voltage, high-speed, and high-power applications. [ABSTRACT FROM AUTHOR]

The longest-chain and Greedy Heaviest Observed Subtree (GHOST) protocols are the two most famous chain-selection protocols to address forking in Proof-of-Work (PoW) blockchain systems. Inclusive protocol was proposed to lower the loss of miners who produce stale blocks and increase the blockchain throughput. This paper aims to make an analytical-model-based quantitative comparison of their capabilities against selfish mining attack. Analytical models have been developed for the longest-chain protocol but less to the GHOST protocol. However, the blockchain dynamics and evolution are different when adopting different chain-selection protocols. Therefore, the corresponding analytical models and/or the formulas of calculating metrics (such as miner profitability and system throughput) may be different. To address these challenges, this paper first develops a novel Markov model and the formulas of evaluation metrics, in order to analyze a GHOST-based blockchain system under selfish mining attack. Then extensive experiments are conducted for comparison and we observe that: (i) The GHOST protocol is more resistant to selfish mining attack than the longest-chain protocol from the aspect of relative revenue of selfish miners. (ii) Inclusive protocol can promote the security (evaluated in terms of miner profitability) improvement of the system which has little total computational power or a high forking probability. Additionally, the longest-chain protocol is more sensitive to inclusive protocol than GHOST protocol. (iii) It is hard for each of the two common-used difficulty adjustment algorithms to achieve higher system throughput and security. [ABSTRACT FROM AUTHOR]

The high operating voltage and switching speed of silicon carbide (SiC) MOSFETs have significant impacts on parasitic elements. This leads to a limitation in the performance of the devices. Especially in the bridge-leg configuration, the coupling of the parasitic elements, in the upper and lower bridge-legs, produces knock-on effects, which complicates the modeling development to reveal the underlying mechanisms. This paper presents a detailed piecewise linear analytical model for bridge-leg configured SiC MOSFETs, which takes into account their characteristics and all parasitic elements. The novelty of the proposed model lies in the fact that the critical parameters in each stage are distinguished flexibly and emphatically according to their influence weights to the corresponding main variables. Therefore, the complexity of the model which considers all parasitic elements is reduced but the critical impacts on the switching processes are carefully kept. The turn-on and turn-off processes are analyzed stage-by-stage in detail with the derived critical parameters equivalent circuits, and the mechanism underlying how each critical parameter influences the model is revealed individually. Furthermore, based on this model, the impact mechanisms and trends of the switching rate variation, the power loop attenuation oscillation, and the driver loop crosstalk phenomenon for different critical parameters are analyzed emphatically. Double pulse measurements with a 600 V/20A SiC MOSFETs based bridge-leg test circuit are used for the experimental verification of the accuracy of the model and the trends of the critical parameters' impacts.

This paper presents a comprehensive $I-V$ model for the evaluation of above threshold DC characteristics of trigate AlGaN/GaN FinFETs for both depletion and inversion mode of operations. For the depletion mode, 2DEG carrier concentration, $n_{s}$ , is evaluated considering the trigate geometry of the device, which is then used to assess drain current $(I_{\text {2D}})$ for both the linear as well as the saturation region of operations. At a relatively higher gate bias, where the 2DEG is fully un-depleted, a significant rise in the drain current is observed which is associated with the creation of two additional side channels in the GaN layer of AlGaN/GaN FinFET, caused by the inversion of carriers. This component of the drain current, referred to as inversion current ( $I_{inv}$ ), is modeled using the solution of a 2D Poisson equation. The total current ( $I_{ds}$ ) is the summation of both the depletion as well as the inversion currents ( $I_{ds} = I_{inv} + I_{\text {2D}}$ ). The developed technique is validated using experimental data and is seen to exhibit a good degree of accuracy. Therefore, the proposed model could serve as a useful tool to predict AlGaN/GaN FinFETs output and transfer characteristics.

To mitigate the ever worsening “Power wall” and “Memory wall” problems, multi-core architectures with multi-level cache hierarchies have been widely accepted in modern processors. However, the complexity of the architectures makes modeling of shared caches extremely complex. In this article, we propose a data-sharing aware analytical model for estimating the miss rates of the downstream shared cache under multi-core scenarios. To avoid time-consuming full simulations of the cache architecture required by conventional approaches, the proposed model can also be integrated with our refined upstream cache analytical model, which also evaluates coherence misses with similar accuracies of state-of-the-art approach with only one tenth time overhead. We validate our analytical model against gem5 simulation results under 13 applications from PARSEC 2.1 benchmark suites. Compared to the results from gem5 simulations under 8 hardware configurations including dual-core and quad-core architectures, the average absolute error of the predicted shared L2 cache miss rates is less than 2% for all configurations. After integrated with the refined upstream model with coherence misses, the overall average absolute error in 4 hardware configurations is degraded to 4.82% due to the error accumulations. As an application case of the integrated model, we also evaluate the miss rates of 57 different multi-core and multi-level cache configurations.

In this paper, a compact model for the double-gate Reconfigurable Field-Effect Transistor (RFET) is presented. Firstly, the physics-based surface potential model is derived by solving Poisson’s equation at different channel regions. Then an explicit expression of drain current is analytically obtained based on the theory of band-to-band tunneling at the Schottky junction. The proposed model shows excellent agreement with TCAD simulations which have been calibrated with experimental data. Finally, the compactible model is implemented in Verilog-A language without convergence problem, and proven by the RFET-based logic circuit.

In this article, a clear analytical model for predicting the performance of permanent magnet (PM) eddy current couplers is proposed. The interaction of the reaction magnetic fields between adjacent eddy current rings was considered for the first time. Based on a magnetic equivalent circuit (MEC) and the Ampere circuital theorem, the accurate distribution of the air gap magnetic field under different slip velocities was deduced in a 2-D model, and the analytical expression of the transmission torque was obtained. 3-D effects were also taken into account to calibrate the model. The validity of the analytical model was verified by comparison with results from the 3-D finite element method (FEM). The comparison shows that the analytical model can accurately predict the magnetic field distribution and transmission torque over a wide range of slip velocity variations. This model can greatly reduce the number of calculations required and save time, and it is suitable for the preliminary design and optimization of PM eddy current couplers. [ABSTRACT FROM AUTHOR]

The cascaded (brushless) doubly fed induction machine (CDFIM) is a promising substitute for the commonly used doubly fed induction machine (DFIM) for wind power application. The CDFIM offers reliable performance and low maintenance due to the absence of slip rings and graphite brushes. In this study, a detailed analytical model for the CDFIM is proposed in order to clearly show the controllable input (i.e., current from the inverter side) and output (i.e., total output torque) relationship. The proposed model is expressed in the frequency (Laplace) domain. Field-oriented (i.e., vector) control approach is adopted in order to achieve a precise dynamic model for the grid-connected CDFIM. The steady-state and dynamic behaviors of derived torque terms are presented and explained individually. Dynamic response of the total output torque is calculated both analytically and numerically in a simulation, and the results are shown to be consistent. Next, the torque-sharing and power-sharing concepts of the CDFIM are presented to further study the system behavior under different rotor velocities. Finally, to verify the proposed model, an experimental setup using a cascaded DFIM was used, and the results are reported. [ABSTRACT FROM AUTHOR]

Axial-flux magnetic-geared double-rotor machines (AMGDRMs) are characterized as a potential key component of the power-splitting system in hybrid electric vehicles (HEVs), but its conventional configuration suffers from the high axial magnetic force. In this article, an interior-modulating-rotor AMGDRM (IMR-AMGDRM) is proposed to solve this problem. To reduce computation burden, an analytical model of the IMR-AMGDRM is proposed based on the subdomain method. The analytical expressions of the magnetic field distribution and electromagnetic performances, such as torque and axial force, are developed. Finally, the results of the proposed analytical model are compared with those of the 3-D finite element analysis (FEA). The influences of the geometrical parameters of the ferromagnetic pole pieces and permanent magnets (PMs) are also investigated by the analytical model and 3-D FEA. The accuracy and the cause of the calculation error of the analytical model are studied. [ABSTRACT FROM AUTHOR]

A new analytical model for the calculation of the shielding effectiveness of multilayer infinite metal meshes is proposed. This model is based on the previously developed one for single- and double-layer metal shielding grids. It enables accurate and fast calculations of the shielding effectiveness of multilayer metal meshes with different air interlayers in a wide frequency range. The proposed model considers the ratio of the wire diameter to the aperture size and the layer interspacing. The model is validated by comparison of the results of calculations with the HFSS simulation results. The model validity in a wide frequency range as well as its calculation speed far bigger than that for HFSS is demonstrated. The results of calculations show that the shielding effectiveness of metal meshes can be effectively improved by increasing the distance between the mesh layers and the ratio of the wire diameter to the aperture size. [ABSTRACT FROM AUTHOR]

In this article, we present an analytical model for the surface potential ($\psi _{s}$) for metal–ferroelectric–insulator–semiconductor (MFIS) negative capacitance field-effect transistors (NCFETs) as a function of the gate voltage, by first developing the models regionwise (weak and strong inversion) and then merging them together in the moderate-inversion region by using a smoothing function. This model for $\psi _{s}$ is used subsequently to obtain the charge and capacitance behavior and eventually to the development of the current–voltage model. It considers various important technology parameters, i.e., substrate doping, ferroelectric (FE) and oxide thicknesses, remnant polarization, and coercive field. All the model results showed an excellent match with those obtained from TCAD simulations. It has also been observed that capacitance matching, and thus, gate control, improves with an increase in the FE thickness and the ratio of the coercive field to remnant polarization, which can be utilized effectively in device and circuit designs for low-power applications. The small-signal parameters, extracted from the current–voltage characteristics, show the first-order continuity, thus making the model suitable for circuit simulation. [ABSTRACT FROM AUTHOR]

This article proposes an accurate and computationally efficient hybrid analytical (HA) model for the air-gap magnetic field computation of asymmetric-stator-pole flux reversal permanent magnet machine, which can provide a thorough insight into the working mechanism by taking the slotting effects into account. The proposed HA model combines the subdomain method and Schwarz–Christoffel (SC) transformation, which can account for the stator and rotor slotting effects, respectively. The subdomain method is first employed to predict the air-gap magnetic field considering the rotor slotting effect by converting the machine geometry to a slotless stator model. Afterward, a complex relative permeance function is obtained by the SC transformation, in which the stator slotting effect is taken into account. Finally, the complete air-gap magnetic field distribution of the machine can be efficiently predicted by the proposed HA analytical model. The effectiveness of the proposed HA model is verified by both finite-element analyses and experimental results. [ABSTRACT FROM AUTHOR]

Estimation of elastomer displacements is crucial for predicting the capacitance variation and studying the sensing performance of capacitive six-axis force/torque(F/T) sensors. This paper presented a novel analytical model to improve the estimation accuracy of elastomer displacements for Y-type elastomer capacitive six-axis F/T sensor. The proposed Y-type elastomer capacitive six-axis F/T sensor consists of three main parts, including a Y-type elastomer, a capacitor and a printed circuit board(PCB). Then, the analytical model is established to estimate the elastomer displacements based on Statics and Timoshenko beam theory. In this analysis, the measurement principle of proposed sensor is depicted and the various elastic beams deformations of the elastomer are analyzed with less simplification. Also, FEA simulation is adopted to verify the accuracy of analytical model. The results showed the maximum relative error is 8.12%. Compared with the analytical model of previous method, these obtained analytical model is confirmed to be accurate and higher efficiency. The proposed analytical model is expected to provide a specific theoretical model of estimation, design and optimization for capacitive six-axis F/T sensors. [ABSTRACT FROM AUTHOR]

Current techniques for evaluating the multilayered coating thickness on carbon fiber-reinforced polymer composites are suboptimal; here, we present a new nondestructive microwave method using an open cavity resonator sensor. When the open end of the cavity is positioned on a conductive polymer composite, a resonant cavity is formed. The coating perturbs the surface impedance, causing a resonance frequency shift. In the modeling, the original endplate perturbation theory for a closed resonant cavity is modified, incorporating the effect of the coating. One-, two- and multilayered coating cases are studied, and a linear relationship is revealed between the resonance frequency shift and the coating thickness change. The accuracy of the model is confirmed by electromagnetic simulation performed with CST software and actual measurements. It is shown that the proposed sensor is insensitive to the conductivity anisotropy of the composite examined, offering easy implementation. For the coating thickness estimation, errors within ±5% have been observed, where two reference cases are used as a simple form of calibration. The method presented here offers efficient on-site evaluation of coatings on composite structures of aircraft and other applications. [ABSTRACT FROM AUTHOR]

In this paper, superposition methods including the superposition of a single stator tooth and the superposition of a single rotor tooth, are proposed to predict the open-circuit performances of flux-reversal permanent magnet (FRPM) machines. By the proposed superposition methods, the electromagnetic performances, such as air-gap flux density, electromotive force, cogging torque, and unbalanced magnetic pull (UMP) are investigated and verified by 2D finite element analysis (FEA). Further, according to the superposition methods, cogging torque reduction techniques can be acquired from both stator side and rotor side. In addition, the influence of stator-slot/rotor-pole-pairs (slot/pole) combination on UMP is also studied, and consequently, a reasonable slot/pole combination rule is suggested to avoid UMP. Then, an improved configuration for UMP reduction is also investigated and verified by FEA. Finally, the prototype machines are manufactured and tested to further verify the theoretical analysis and FEA predictions. [ABSTRACT FROM AUTHOR]

High performance computing (HPC) demands huge memory bandwidth and computing resources to achieve maximum performance and energy efficiency. FPGAs can provide both, and with the help of High Level Synthesis, those HPC applications can be easily written in high level languages. However, the optimization process remains time-consuming, especially when based on trial-and-error bitstream generation. Model-based performance prediction is a practical and fast approach for kernel optimization, specially if done with information from pre-synthesis reports. This article presents an analytical model focused on memory intensive applications that captures the memory behavior and accurately predicts the kernel execution time within seconds rather than hours, as bitstream generation requires. The model has been validated with two DRAM technologies: DDR4 and HBM2, with a set of microbenchmarks and high performance computing applications showing an average error of 11% for DDR4 and 10% for HBM2. Compared with previous studies, our predictions at least halve the estimation error. [ABSTRACT FROM AUTHOR]

In this article, an analytical model to predict the instantaneous torque profile in a synchronous reluctance (SyncRel) machine is developed, which can predict the machine's torque performance based on either inductance or flux-linkage harmonics. High-performance torque-ripple-sensitive applications have stringent torque ripple and noise and vibration requirements to satisfy the overall system requirements. The prediction of the torque ripple is critical in these applications to identify the root cause and then mitigate the torque ripple through design alternations under different loading (current) conditions of the machine. The developed analytical model provides a simpler, intuitive, and significantly less time consuming yet reasonably accurate alternative approach compared to multiple finite-element runs on the same baseline design. The developed analytical model provides design support through fast iterations with design variations or for motor electronic controller implementation. A 2-D finite-element model has been developed to validate the proposed analytical model. The analytical model is also validated with experimental data of a 30-slot four-pole SyncRel machine. [ABSTRACT FROM AUTHOR]