Analytical Time-domain Model Research Articles

2-D Analytical Model for Computing Eddy-Current Loss in Nonlinear Thick Steel Laminations

In this article, we propose an analytical method to compute the eddy-current loss in nonlinear thick steel laminations (3–12 mm) by considering the return path of the eddy currents. Initially, a 2-D finite-element (FE) model is applied to segregate losses measured from toroidal material samples into hysteresis and eddy-current loss components to use them as reference. Afterward, a 2-D analytical time-domain model is proposed for the eddy currents based on the solution of the 2-D field problem. The time-domain model is then used to derive a simple frequency-domain eddy-current loss formulation for the sinusoidal flux density case with the inclusion of a skin-effect correction factor, which accounts for the nonlinearity of the material. Highly accurate results are obtained from the proposed model compared to FE reference results with a mean relative error of 5.1% in the nonlinear region.

Modeling and Performance Analysis of MLGNR Interconnects

In this work, we have presented the temperature-dependent analytical time domain model for top-contact multilayer graphene nanoribbon (TC-MLGNR) and side-contact multilayer graphene nanoribbon (SC-MLGNR) interconnects for 16[Formula: see text]nm technology node. Using this analytical model, the effective mean free path (MFP) is calculated for different temperatures and then the resistance of GNR interconnect is calculated. The lower resistance of MLGNR is one of the important factors to reduce interconnect delay. The equivalent capacitance for TC-MLGNR is also calculated. It is observed that the performance of graphene interconnects seriously deteriorates due to the presence of the interlayer capacitance. The presence of this interlayer capacitance increases the equivalent capacitance which is the dominant factor that inhibits the performance of TC-MLGNR interconnects. Further, the delay ratio between copper and TC-MLGNR for different interconnect lengths and for three different temperatures (233[Formula: see text]K, 300[Formula: see text]K, 378[Formula: see text]K) is calculated. It is observed that for longer interconnect lengths, the improvement in delay in TC-MLGNR is less as compared to traditional copper-based interconnect at low temperature. Further, power delay product (PDP) of copper and TC-MLGNR for different interconnect lengths and for three different temperatures is also calculated. It is shown that TC-MLGNR interconnects have better PDP than copper interconnects. The crosstalk analysis is performed to estimate the noise and overshoot/undershoot in TC-MLGNR and SC-MLGNR interconnects. It is shown that SC-MLGNR interconnect has better performance as far as the crosstalk is concerned as compared to that of Cu and TC-MLGNR interconnects.

Analytical Modeling of Silicon Microring and Microdisk Modulators With Electrical and Optical Dynamics

We propose an analytical time-domain model for microring and microdisk modulators, which considers both their electrical and optical properties. Theory of the dynamics of microring/microdisk is discussed, and general solutions to the transfer matrix representation are presented. Both static and dynamic predictions from the model are compared to measurement results to demonstrate the accuracy of our model. Static predictions and measurements are presented for power and phase responses, whereas dynamic predictions and measurements are presented for small-signal and large-signal operations. The model verifies that the chirping and modulation bandwidth of the modulators depend on the detuning state. Finally, the accuracy and scalability of several techniques employed in the model are discussed.

Compact models and delay computation of sub-threshold interconnect circuits

Ultra-low power designs extensively exploit the sub-threshold region of operation of Complementary metal-oxide semiconductor (CMOS) circuits. Though sub-threshold circuit operation shows huge potential towards satisfying the ultra-low power requirement, increased crosstalk and delay have become serious design challenges particularly for sub-threshold interconnects. In this paper, novel analytical time-domain models governing the output voltage and crosstalk-induced delay of CMOS gates driving coupled resistive---capacitive interconnect in sub-threshold domain are presented. Subsequently, the transient analysis of simultaneously switching two and three coupled interconnects is carried out. It is demonstrated that the modeling of driver by linear resistance can lead to about 38 % average error in the estimation of propagation delay. The numerical results illustrate that the proposed model quite accurately estimates the performance of coupled on-chip interconnects. An average error of less than 7 % is observed in estimation of waveform shape and delay.

Signal to Noise Ratio Penalty Analysis for Radio over Free Space Optical Systems

Due to ever-increasing demand for capacity and quality in wireless communication links, lead to inspire researchers to innovate new design methodologies and concepts over wireless systems and networks with the ultimate aim of achieving a next-generation network. These researches must ensures data rates similar to those offered by optical fiber systems but at the fraction of its deployment cost. Among the emerging technologies is the new innovative radio on freespace optics system, referred to as Radio over Free Space Optics (RoFSO), which is the main interest of this paper. RoFSO systems have been recognized as a promising wireless interconnecting technology. Such system combines the radio over fiber (RoF) technology comprising heterogeneous wireless services and Fiber Space Optics (FSO) link. In this paper, an analytical time-domain model is presented to analyze the radio over free space optical (RoFSO) systems considering scintillation effect with the log-normal distribution. This analytical model uses a dual-drive MachZehnder modulator (DD-MZM) and photodetector (PD) for optical single sideband (OSSB) signals.

Analytical time-domain turning model with multiple modes

An analytical time domain model is developed to predict the motion of a multi-mode cutting tool during orthogonal turning operations. This model is an extension of a single mode model that finds the solution to the governing delay differential equation (DDE) as a combination of constituent curves (sequential responses) which are independent of the delay term, τ. In the current model, the delay independent constituent curves are found through a recursive state-space solution wherein the individual modal displacements are determined for each sequential response. In this paper, the solution process is described in detail for a two mode system and the resulting analytical time responses are compared with numerical simulations.

Analytical Time-Domain Models for Performance Optimization of Multilayer GNR Interconnects

In this paper, we are proposing novel analytical time domain models for side contact and top contact multilayer graphene nanoribbon (MLGNR) interconnects. Our proposed models give physical insights about the transient behavior of these MLGNRs. The proposed models have been verified with existing data as well as exhaustive simulation and exhibit excellent accuracy. Based on our analysis, we identify limiting factors that need to be considered for the design of optimum top contact MLGNRs that exceed the performance of copper and match that of side contact MLGNR interconnects. Finally, we compare the performance of our optimum top contact MLGNRs with optical interconnects to predict the future roadmap for next generation interconnect technology.

Robustification of iterative learning control and repetitive control by averaging

This paper describes a recently developed averaging technique to robustify iterative learning and repetitive controllers. The robustified controllers are found by minimising cost functions that are averaged over either multiple analytical time-domain models or experimental frequency-domain data. The aim is to produce a technique that is simple and general, and can be applied to any iterative learning control (ILC) or repetitive control (RC) design that involves the minimisation of a cost function. Substantial improvement in convergence to zero tracking error in the presence of model uncertainties has been observed for both ILC and RC by this averaging technique.

Analytical Time-Domain Model for Radio over Free Space Optical (RoFSO) Systems Considering the Scintillation Effect

An analytical time-domain model is presented to analyze a radio over free space optical (RoFSO) system considering the scintillation effect with a log-normal distribution. This analytical model uses a dual-drive Mach-Zehnder modulator (DD-MZM) and photodetector (PD) for typical optical double sideband (ODSB) and single sideband (OSSB) signals. We show the output current of PD as a function of the summation of each frequency component in time domain. Finally, we calculate the received signal power with respect to the power spectral density (PSD) and derive a closed-form average bit error rate (BER) performance.

Analytical time-domain model of transient eddy current field in pulsed eddy current testing

The transient eddy current field is analytically modeled by applying inverse Laplace transform to pulsed eddy current testing. The closed-form solution to transient eddy current field in a complex domain is obtained by using the truncated region eigenfunction expansion (TREE) method and the theory of reflection and transmission of electromagnetic waves. After extensive algebraic transform, the poles of the developed model and corresponding residues are able to be calculated. As a result, partial fraction expansion can be used to split up the complicated complex-domain model into the forms that are listed in the Laplace Transform table. Therefore, it is easy to derive the time-domain solutions to transient eddy current field with step and exponential current excitations respectively. The derived time-domain model not only has some advantages in the sense of implementation and efficiency, but also removes the Gibbs phenomenon. Finally, the inverse Fourier transform of induced voltage in the probe is performed and the good agreement demonstrates the validity of the established model.

Modeling of Dry Sliding Wear Using a Systematic Approach

Virtual life testing is becoming a widely accepted methodology for predicting the life span of products. In this method, reliable models are important to predict different aspects of design performance, one of which is wear. Wear and has been a subject of numerous scientific and empirical investigations. Due to the complex and dynamic nature of the phenomena, there is no general wear model, which can be adopted for all wear problems. A systematic approach to the modelling of dry sliding wear using analytical time domain models is presented in this paper. Given the sliding distance, the model is capable of predicting wear status in transient (running-in) and steady-state operating conditions. The validity of the modelling approach is demonstrated by comparing the predicted results of wear experiments, with that actually measured. For simplicity, the model is based on sliding distance as input variable, while other factors like temperature, load, surface conditions are treated as constant. A simple geometry of sliding polymer-based contacts is used for establishing of wear model.