Stability of model-reference systems with random impulsive inputs

The stability of the gain-adjusting loop of a simple model-reference adaptive-control system is investigated. The input to system and model is a sequence of impulses of random magnitude. The resulting behaviour is determined by an infinite product, and from this a necessary and sufficient criterion for the stability of the adaptive-loop gain is deduced.     

Solution of nonlinear time-variant systems with random inputs

The adjoint method of analysis and Booton's equivalent-gain technique for nonlinearities can be combined, using a successive-approximation method, to analyse nonlinear time-varying systems where the input is random. The solution is performed on an analogue computer. Logic control of the computer speeds the calculation.     

Suboptimal digital control systems with bounded control inputs

Bounds on the control inputs to a linear system are dealt with in a manner suitable for online computer control. The method guarantees that for r control inputs the constrained optimum will be located in, at most, r steps.     

A hybrid modeling method for mechanical systems

In this paper, a system identification method for hybrid systems switched by the magnitude of velocity and displacement is proposed. First, it is shown that the regression vector space of a mechanical system switched by the magnitude of velocity cannot be separated by a hyperplane. Then a method based on support vector machines with a polynomial kernel is proposed. The effectiveness of the proposed method is shown by simulations and experiments.     

A digital calibration method for synthetic aperture radar systems

A basic method to calibrate imagery from synthetic aperture radar (SAR) systems is presented. SAR images are calibrated by monitoring all the terms of the radar equation. This procedure includes the use of both external (calibrated reference reflectors) and internal (system-generated calibration signals) sources to monitor the total SAR system transfer function. To illustrate the implementation of the procedure, two calibrated SAR images (X-band, 3.2-cm wavelength) are presented, along with the radar cross-section measurements of specific scenes within each image. The sources of error within the SAR image calibration procedure are identified     

An efficient approach to ARMA modeling of biological systems withmultiple inputs and delays

Presents a new approach to AutoRegressive Moving Average (ARMA or ARX) modeling which automatically seeks the best model order to represent investigated linear, time invariant systems using their input/output data. The algorithm seeks the ARMA parameterization,which accounts for variability in the output of the system due to input activity and contains the fewest number of parameters required to do so. The unique characteristics of the proposed system identification algorithm are its simplicity and efficiency in handling systems with delays and multiple inputs. The authors present results of applying the algorithm to simulated data and experimental biological data. In addition, a technique for assessing the error associated with the impulse responses calculated from estimated ARMA parameterizations is presented. The mapping from ARMA coefficients to impulse response estimates is nonlinear, which complicates any effort to construct confidence bounds for the obtained impulse responses. Here a method for obtaining a linearization of this mapping is derived, which leads to a simple procedure to approximate the confidence bounds     

激光陀螺随机误差建模方法研究

随机误差是陀螺的主要误差。为了减小随机误差对激光陀螺精度的影响。介绍了依据激光陀螺漂移数据建立时间序列模型的方法并进行了建模实验,并在此基础上采用卡尔曼滤波算法对激光陀螺的漂移数据进行了处理,取得了较好的效果。结果表明,此方法能有效地抑制激光陀螺的随机误差,提高激光陀螺的精度。     

A quadratic sigmoid neural equalizer for nonlinear digital magneticrecording channels

A new neural equalizer is proposed in order to compensate for intersymbol interference and to mitigate nonlinear distortions in digital magnetic recording systems. The proposed equalizer uses the quadratic sigmoid function as the activation function. The performance of the proposed equalizer is compared to those of a decision-feedback equalizer (DFE) and a neural decision feedback equalizer (NDFE) in terms of bit-error rate in nonlinear digital magnetic recording channels. Simulation results demonstrate that the proposed equalizer outperforms both DFE and NDFE     

Reliability modeling of multi-state degraded systems with multi-competing failures and random shocks

In this paper, we develop a generalized multi-state degraded system reliability model subject to multiple competing failure processes, including two degradation processes, and random shocks. The operating condition of the multi-state systems is characterized by a finite number of states. We also present a methodology to generate the system states when there are multi-failure processes. The model can be used not only to determine the reliability of the degraded systems in the context of multi-state functions, but also to obtain the states of the systems by calculating the system state probabilities. Several numerical examples are given to illustrate the concepts.     

Eye pattern evaluation in high-speed digital systems analysis byusing MTL modeling

A method for simulating the eye pattern of high-speed digital signals propagated on printed circuit boards using multiconductor transmission-line modeling is proposed in this paper. The approach takes into account the frequency-dependent properties of the dielectric materials of the board and of the conductors. The validation is performed by comparing the modeling with measurements taken from the literature, and directly performed on test boards specially design for this study     

A nonlinear filtered‐x prediction error method algorithm for digital predistortion in digital subscriber line systems

Digital predistortion of nonlinear systems is an important topic in many practical applications. This paper considers direct predistortion of a Volterra system by connecting in tandem an adaptive Volterra predistorter. The coefficients of the predistorter can be recursively estimated using the nonlinear filtered‐x least mean squares (NFxLMS) algorithm. In this paper, the prediction error method (PEM) is used to derive a novel nonlinear filtered‐x PEM (NFxPEM) algorithm. A simulation study on Volterra systems shows that the NFxPEM algorithm more significantly suppresses spectral regrowth and converges much faster than the NFxLMS algorithm. Also, the NFxPEM algorithm is used in this paper to design more efficient digital predistorter—as compared with the NFxLMS algorithm—for digital subscriber line systems. Copyright © 2012 John Wiley & Sons, Ltd.     

A flexible array synthesis method using quadratic programming

A highly flexible synthesis method for an arbitrary array is proposed to best approximate a desired array pattern in a minimum-mean-square-error sense. The basic idea of the technique is to form a quadratic program with its cost function given by the mean-square error between the array response and a properly selected pattern described by a known mathematical function. This quadratic program can be a constrained or unconstrained optimization problem depending on the requirements of the desired array pattern. In formulating the quadratic program, no assumption has been made on the gain/phase response or characteristics of the individual array elements. Therefore, one can synthesize an array of arbitrary shape to any appropriate pattern with the characteristic of the array elements taken into consideration as long as one is able to model the array accurately. The proposed method is used to synthesize arrays of different shapes, linear as well as planar arrays (including rectangular and circular planar arrays), using a Chebyshev polynomial or zero function as a design template, to illustrate the feasibility of the proposed method     

A computer modeling approach for LSI digital structures

The paper presents a novel modeling approach to LSI MOST circuits performed at the gate level. A macromodel is analytically derived and provides a direct relationship between the input function and output response of the gate. This approach or macromodeling has been implemented for over 10 000 devices in LSI with only 32K of computer core and very fast computing time. The method employed relates directly the performance parameters (e.g., turn-on voltage, rise, and fall times, etc.) to the device parameters. An insight into the propagation delay of LSI structures is gained by statistically studying the transient performance of the system using Monte-Carlo techniques. Experimental results give ample evidence of good agreement with the computed results, for which various values of x0, oxide thickness, are used.     

A survey of digital computer memory systems

Many types of storage and memory systems have been proposed for use in digital computing systems. This survey paper discusses only the various systems whose reaction time is faster than human reaction time, employing a historical approach to the subject. Criteria for evaluation are discussed, and comparisons given among the different systems as to general applicability, ease of construction and use, speed of operation, latency time, memory span, and economy     

基于离散对数和二次剩余的门限数字签名体制

本文将数字签名体制与Shamir秘密分享方案相结合提出了一种门限数字答名体制，其安全性基于有限域上求解离散对数的困难性和在特定条件下求解二次剩余的困难性。提出了在该体制中防止恶意参与者利用假“部分签名”进行欺诈以阻止签名、非法用户或签名的生成者伪造签名的有效措施。     

Analysis of LMS algorithm with inputs from cyclostationary random processes

The least mean square (LMS) algorithm is investigated for inputs from nonstationary random processes having periodic (period P) statistics. By defining P different coefficient vectors, each vector can be shown to converge in the mean' to a biased solution which is dependent upon the algorithm step size mu .<>     

Analysis of nonlinear systems with multiple inputs

Analytical modeling of communication receivers to account for their nonlinear response to multiple input signals is discussed. The method is based on the application of the Wiener-Volterra analysis of nonlinear functionals. The derived analytical relations were embodied in a computer program which provides nonlinear transfer functions of large circuits specified by their parameters. This method was applied to the prediction of behavior of communication receivers in the presence of interference. Examples illustrate the method and demonstrate its validity in the small-signal region.     

A high speed, fully digital IC random number generator

System-on-a-chip solutions require hardware based integrated circuit random number generators for trustworthy transmission of information. This paper presents, a fully digital, high speed ASIC random number generator based on ring oscillators. Prototypes have been designed and fabricated in HHNEC's 0.25 μm eFlash process with a supply voltage of 2.5 V. The circuit occupies 0.052 mm² and dissipates 0.095 W of power. IC design level experiences, measurements, analysis of measurements and statistical test results are also demonstrated. Instead of resilient function, employed in the previous ring oscillators based design, which decreases the throughput by a factor of 16, we propose to use only a simple Von Neumann corrector which improves this result by a factor of 4. We achieved fulfilled test results from NIST 800-22 test suit after Von Neumann corrector with a sampling frequency of 74 MHz. Since, Von Neumann corrector is used as a post-processor, the throughput becomes 18.5 Mbps. Furthermore, we propose to use doubled ring oscillators structure, thus, a 125 Mbps throughput, which is the highest data rate to date with fulfilled test results, is attained without any postprocessing. The results were repeatable numerous times.