Fast algorithms for block toeplitz matrices with toeplitz entries

This paper deals with efficient triangularization, inversion and system solution of block Toeplitz matrices with Toeplitz entries. Fast algorithms are developed which taking into advantage the joint Toeplitz structure, reduce by a factor of two the complexity of existing algorithms for general block Toeplitz matrices.     

A symmetric rank-revealing toeplitz matrix decomposition

In signal and image processing, regularization often requires a rank-revealing decomposition of a symmetric Toeplitz matrix with a small rank deficiency. In this paper, we present an efficient factorization method that exploits symmetry as well as the rank and Toeplitz properties of the given matrix.     

基于Toeplitz矩阵的波束空间新算法

为保留渡束空间算法优点,降低算法对阵列的要求,及对相干信号源有效,提出了基于Toeplitz矩阵的波束空间多重信号处理算法-BST-MUSIC.算法将任意阵列的波束域输出及均匀线阵的阵元输出综合处理得到Toeplitz矩阵,对其修正处理后采用MUSIC算法进行DOA估计.由推导过程知:算法能够增强或抑制指定空域内的信号;能使相干信源等效为独立信源;在任意阵列与均匀线阵阵元不重合情况下能够有效地抑制噪声;只需一个子阵为均匀线阵,降低了算法对阵列的要求.     

连续时间混沌系统的参数自适应同步

针对参数不一致系统以及同步无法实现的系统，基于误差渐进稳定收敛到零的原理，提出参数自适应加反馈同步法。数值模拟表明，通过选择合适的反馈系数，能够成功地实现混沌同步，并进一步将结果推广到超混沌系统。     

Parametric identification of low-frequency disturbances in radio engineering systems

An approach to solving the problem of identifying low-frequency random disturbances is examined in a suboptimal way. An example of the calculation of the introduced approach is given.     

Parametric coupling between modes of propagation in nonconservative systems

The small-signal theory of the parametric coupling of two waves in the presence of attenuation is summarized. The example chosen to illustrate the effects of losses on parametric coupling is two transmission lines coupled by a temporally and spatially varying capacitance. Included are analyses of contra- and co-flow parametric coupling, i.e., group velocities of the waves in the opposite and the same directions, respectively, with the pumping frequency either the sum or difference of the frequencies of the two waves. Contra-flow coupling with sum frequency pmnping is discussed in detail and it is found that the solutions for the mode amplitudes with loss are exponential, while without losses they are sinusoidal.     

Formation of the block toeplitz matrix for two-dimensional PLSI Polynomials

The planar least-squares inverse (PLSI) polynomials are used for stabilization of two-dimensional unstable recursive filters. In order to obtain the PLSI polynomials, the main work involved consists in forming a set of linear equations and then solving them. In this paper we present an efficient and simple method to form the necessary set of linear equations (i.e., the required coefficient matrix) for a chosen pattern and order of the desired PLSI polynomial, starting from the denominator polynomial of a two-dimensional unstable recursive filter.This work was financed by the Alexander von Humboldt Foundation, Bonn.On leave from the Department of Electrical and Electronics Engineering, S.V. University, Tirupati-517502, A.P., India.     

Parametric adaptive control of multimachine power systems with nonlinear loads

The novel concepts and definitions of M derivative and M bracket for nonlinear differential algebraic system (NDAS) are introduced, and some related revised results that are similar to the classic differential geometric theory are given. The normal forms of NDAS model are obtained by multi-input multi-output (MIMO) feedback linearization technique. The control expressions derived are based on the linear system theory and the requirements of tracking targets when the relative degree of the system is less than the dimension of the system and the special designated conditions are satisfied. The parametric adaptive controller is obtained for the multimachine power systems with nonlinear loads and undetermined or unknown parameters by the Lyapunov stability theory and method.     

Parametric instability of optical amplifier noise in long-distanceoptical transmission systems

In this paper, the optical amplifier noise accumulation in long-distance optical transmission systems is analyzed under the influence of the parametric process caused by the Kerr effect and group-velocity dispersion. By considering the input signal as a continuous-wave (CW) carrier and the optical amplifier noise as the small modulation, the general theory on the evolution of the optical amplifier noise along the system is proposed. This theory enables us to treat all of the noise enhancement effects, the so called parametric instability, discussed so far in a unified manner. The validation of the theory is finally confirmed by using extensive computer simulations     

Parametric gain in multiwavelength systems: a new approach to noiseenhancement analysis

In the paper, we introduce a new formalism to study noise enhancement induced by parametric gain in wavelength-division-multiplexed (WDM) systems. We also analyze the phenomenon impact in a typical long-haul, dispersion-compensated link, and show its peculiar relevance in WDM systems     

The fundamental subspace sequences of matrix pencils: A toeplitz matrix unified characterization

The geometric theory of the domain of an ordered pair (F, G) of matrices or the geometry associated with matrix pencils provides a unifying framework for the study of algebraic, dynamic and feedback properties of linear singular systems. The key concepts and tools of the geometry are the notions of the (F, G)-, (G, F)-invariance and a set of subspace sequences. In this paper, an alternative characterization of these sequences is given based on the properties of the partitioned null spaces of appropriate sequences of Toeplitz matrices defined by the (F, G) pair. The results provide a simple procedure for the computation of the limit spaces of these sequences and clearly cover corresponding problems of the singular, implicit systems theory.     

Parametric cumulant based phase estimation of 1-D and 2-Dnonminimum phase systems by allpass filtering

This paper proposes a parametric cumulant-based phase-estimation method for one-dimensional (1-D) and two-dimensional (2-D) linear time-invariant (LTI) systems with only non-Gaussian measurements corrupted by additive Gaussian noise. The given measurements are processed by an optimum allpass filter such that a single Mth-order (M⩾3) cumulant of the allpass filter output is maximum in absolute value. It can be shown that the phase of the unknown system of interest is equal to the negative of the phase of the optimum allpass filter except for a linear phase term (a time delay). For the phase estimation of 1-D LTI systems, an iterative 1-D algorithm is proposed to find the optimum allpass filter modeled either by an autoregressive moving average (ARMA) model or by a Fourier series-based model. For the phase estimation of 2-D LTI systems, an iterative 2-D algorithm is proposed that only uses the Fourier series-based allpass model. A performance analysis is then presented for the proposed cumulant-based 1-D and 2-D phase estimation algorithms followed by some simulation results and experimental results with real speech data to justify their efficacy and the analytic results on their performance. Finally, the paper concludes with a discussion and some conclusions     

A Model of Terahertz Parametric Process Including Spontaneous Parametric Down-conversion

Journal of Infrared, Millimeter, and Terahertz Waves - A new numerical model of terahertz parametric process is demonstrated, which takes the spontaneous parametric down-conversion into...     

Parametric mode locking

The conditions under which a synchronously pumped intracavity parameter generation causes mode locking in a homogeneously broadened laser are investigated experimentally and theoretically. An expression for the steady-state duration of parametric mode-locked pulses is derived and compared with experimental results. Contributions from both parametric AM and FM mode locking are included, and the conditions to optimize pulse narrowing, frequency upconversion, and active dispersion compensation are determined and discussed     

Multiple-Idler Parametric Amplifiers

The input resistance and noise performance of multiple-idler parametric amplifiers are examined in this paper. General expressions applicable to any given amplifier are derived. Simplifications resulting from a sinusoidal elastance variation permit writing an expression for the input resistance of an amplifier having any given number of idlers by inspection. These expressions are then applied to examine the properties of an amplifier having two idlers. The conditions required for minimum noise performance are derived, and it is found that high pump frequencies and external resistive loading of one idler are required. When the two-idler amplifier is compared to a conventional single-idler amplifier under those conditions which permit operation of the same diode at the same signal and pump frequencies, it is found that an improvement in noise figure results. However, the single idler amplifier pumped at the optimum frequency is capable of better noise performance, because minimum noise conditions cannot be satisfied for the two-idler device at this pump frequency. When below-signal-frequency pumping is utilized in the two-idler amplifier, the reduction in required pump power is substantial, but the noise figure is degraded by a minimum of approximately 3 dB.     

Parametric photovoltaic cell

A new way of converting light energy into electric power is presented. A capacitor is charged periodically under influence of the chopped light flux. Electric energy stored in the capacitor can be increased by the parametric effect, i.e. the reduction of the capacitance value. The energy conversion process is analysed. The possible applications and limitations of this device are indicated and discussed.