Sharif Digital Repository

The averaged switch modeling approach is a powerful method for representing the behavior of a wide variety of converters through equivalent circuits. The model is not linear and it is common to perform a small signal linearization about an operating point and design a linear controller. Models obtained with such method involve considerable approximation and produce results that are limited for high performance controller designs. In this paper a piecewise affine approximation technique is introduced for modeling PWM converters. This model is much more precise in predicting the dynamic response of averaged nonlinear model comparing the linear model. This paper also presents a piecewise linear... 

In this paper we propose a novel structure of a discrete-time mixed-signal linear equalizer designed for analog front end of Gigabit Ethernet receivers. The circuit is an FIR filter which involves 6 taps based on a coefficient-rotating structure. Here, a simple structure is used for merging digital to analog conversion of the filter's coefficients and multipliers needed for 6 taps. This structure results in high speed and low power dissipation as well as less A/D converter complexity. Simulated in a 0.18 um CMOS technology, this equalizer operates at 125 MHz while dissipating 10 mw from a 1.8 V power supply. © 2006 IEEE  

A large-signal linearization method for operational transconductance amplifiers (OTA) using a combination of cross-coupled quadratic cell and a novel non-linear current injection technique is presented in this paper. Post-layout simulations show that for 180 nm CMOS process with a 1.8 V power supply, total harmonic distortion (THD) at 1.5 V peak-to-peak and 5 kHz input is less than −46 dB. Also, the dynamic range (DR) at given THD is 68 dB with power consumption of 0.64 mW. To verify the performance, the proposed OTA is used to design a new configurable filter in high-frequency range using N-path filter methodology. Universal Butterworth Gm-C active filters are embedded in the proposed... 

There is a growing interest, both from the theoretical as well as experimental side, to test the validity of the quantum superposition principle, and of theories which explicitly violate it by adding nonlinear terms to the Schrödinger equation. We review the original argument elaborated by Gisin (1989 Helv. Phys. Acta 62 363), which shows that the non-superluminal-signaling condition implies that the dynamics of the density matrix must be linear. This places very strong constraints on the permissible modifications of the Schrödinger equation, since they have to give rise, at the statistical level, to a linear evolution for the density matrix. The derivation is done in a heuristic way here... 

The aim of this study is to reduce the computational load in model predictive control of multi-input nonlinear systems. First, the nonlinear system which has a high number of states and inputs is decomposed into several subsystems by solving a linear integer programming problem offline. Then, the model of each subsystem is revised by considering the effect of coupling and interactions of other subsystems. Next, the robust model predictive technique based on linear matrix inequalities is employed to compute control signal for each subsystem. An industrial chemical reaction example is used to illustrate the effectiveness of the proposed method. © 2017 IEEE  

The state-space averaging applied to switched networks generally results in nonlinear systems. It is common to perform a small signal linearization about an operating point to obtain a linear system. When the variations in signals are large, e.g., in PFC rectifiers, the small signal approximation produces results that are susceptible to instability problems. In this paper a class of piecewise linear models merged by fuzzy system are introduced for PWM converters. The necessary and sufficient and conditions for stability of fuzzy models using fuzzy state-feedback controllers are given. The results obtained are illustrated with a buck-boost converter. The simulation and experimental results... 

Design of a classical controller is based on output feedback and structure of the controller. From modern control point of view, the information of input signals, output signals and internal behavior of the system are presented in state space model. In this paper, modern control is used to increase small-disturbance stability of power systems. Although many of existing power plants prefer to use classical Power System Stabilizers (PSS), these controllers have their own problems. Digital implementation of modern controllers is considered as a good advantage of modern PSS. In this paper, a modern control based PSS is designed for Bistun power plant and its output results are compared to the... 

In this paper, we consider the problem of data transmission for {K}- user interference channel (IC) with no channel state information (CSI) at transmitters. Each pair of transceivers with the aid of a particular precoder and a switching pattern structure tries to place its desired signal in a subspace which is linearly independent of interference signals. We show that if the channel values are known only to the receivers, the sum degrees-of-freedom (DoF) of the linear interference alignment (IA) with reconfigurable antenna at receivers is rac {{ { Kr}}}{ {r}^{2}- {r}+ {K}} , where {r} = left lceil{ {rac {sqrt {1+4 {K}}-1}{2}} }ight ceil . For previous methods when 3 leq {K} leq 10^{4} , the...