An efficient hybrid genetic algorithm to design finite impulse response filters

Although genetic algorithms (GAs) have proved their ability to provide answers to the limitations of more conventional methods, they are comparatively inefficient in terms of the time needed to reach a repeatable solution of desired quality. An inappropriate selection of driving parameters is frequently blamed by practitioners. The use of hybrid schemes is interesting but often limited as they are computationally expensive and versatile. This paper presents a novel hybrid genetic algorithm (HGA) for the design of digital filters. HGA combines a pure genetic process and a dedicated local approach in an innovative and efficient way. The pure genetic process embeds several mechanisms that interact to make the GA self-adaptive in the management of the balance between diversity and elitism during the genetic life. The local approach concerns convergence of the algorithm and is highly optimized so as to be tractable. Only some promising reference chromosomes are submitted to the local procedure through a specific selection process. They are more likely to converge towards different local optima. This selective procedure is fully automatic and avoids excessive computational time costs as only a few chromosomes are concerned. The hybridization and the mechanisms involved afford the GA great flexibility. It therefore avoids laborious manual tuning and improves the usability of GAs for the specific area of FIR filter design. Experiments performed with various types of filters highlight the recurrent contribution of hybridization in improving performance. The experiments also reveal the advantages of our proposal compared to more conventional filter design approaches and some reference GAs in this field of application.     

设计稳定约束最小二乘无限冲击响应滤波器的序列最小化方法

无限冲击响应(infinite impulse response, IIR)数字滤波器不具有内禀稳定性, 因此在其实际设计中要施加稳定性约束. 稳定三角形条件是一种充分必要且线性的稳定性约束条件, 为了充分利用该条件, 本文使用基于二阶因子迭代更新的序列最小化技术将IIR滤波器的约束最小二乘设计问题转化为一系列的约束最小二乘子问题, 在每一个子问题中, 有且只有一个二阶分母因子连同整个分子被优化, 其他的二阶分母因子保持不变. 设计实例表明此方法能比现有方法得到性能更好的滤波器.     

Electromagnetic design of microwave filters using the finite element method

We present two complex microwave filter designs using the finite element method (FEM). A metallic cavity, loaded by low-loss dielectric plates is first optimized to obtain a high unloaded quality factor resonator. An original synthesis approach is then proposed to design a three-pole dielectric loaded cavity filter. The FEM is also applied to characterize a filter element, a dielectric resonator (DR) coupled on a whispering gallery mode (WGM) to two microstrip lines. A generalized [S] matrix is computed. Different elements are then put together to generate complex filtering responses. © 1997 John Wiley & Sons, Inc. Int J Microwave Millimeter-Wave CAE 7: 167–179, 1997.     

Influence and tuning of tunable screws for microwave filters using least squares support vector regression

This article presents an approach that can analyze the influence of tunable screws and perform a computer‐aided tuning for microwave filters. In the approach, a machine‐learning model that reveals the influence of tunable screws on the filter response is first developed by least squares support vector regression, according to some data from the tuning experience of filters. Then a computer‐aided tuning procedure based on the model is proposed, and the obtained adjusting amount of tunable screws can assist an unskilled operator to perform a fast and accurate tuning. The approach is validated by some experiments and the results confirm the effectiveness. The approach is particularly suitable to the computer‐aided tuning of volume‐producing filters. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

Optimum design of 6‐18 GHz ultra‐wideband microstrip filters with arbitrary source and load impedances by the least mean squares Method

In this article, the method of least mean squares (LMS) is employed to design ultra‐wideband (UWB) filters with various input and output port impedances in 6‐18 GHz frequency range. Optimization process on the circuit dimensions is done by MATLAB and AWR microwave office softwares utilizing exact closed‐form relations for microstrip transmission lines and microstrip T‐junction discontinuities. The advantages of this method are its simplicity, fast design time, including impedance matching. Two design examples are depicted in the article. To validate the designed structures, the circuit model results are compared with full‐wave analysis and measurements. The first design example corresponds to equal source and load impedances. For this design, maximum measured transmission coefficient in the frequency range 5.9‐16.6 GHz is obtained as ?12 dB, upper out‐of‐band rejection around image frequency is better than ?17 dB and lower out‐of‐band rejection at 5 GHz is obtained better than ?30 dB. The second design example describes the case of unequal source and load impedances.     

基于FIR神经网络的风电场虚拟风速传感器

风电机组风速传感器易发故障,故障可能导致机组安全风险和发电量损失。针对现行的故障处理方法因与机组控制策略紧密耦合而日益面临挑战,提出了一种基于数据处理的虚拟风速传感器原理与方法：由风电场上风向测量风速计算下风向推算风速,用推算风速取代故障传感器。着重讨论了基于FIR神经网络的推算风速计算方法和计算模型,探讨了系统实现的关键技术。实验证明了虚拟传感器的误差在机组控制系统可接受的程度内。提出的方法独立于机组自身属性,具有普遍适用性,可部署在任意类型的场,在物理传感器故障时向机组提供风速信号,支撑风电机组持续安全运行。     

Iterative constrained weighted least squares estimator for TDOA and FDOA positioning of multiple disjoint sources in the presence of sensor position and velocity uncertainties

Sensor position and velocity uncertainties are known to be able to degrade the source localization accuracy significantly. This paper focuses on the problem of locating multiple disjoint sources using time differences of arrival (TDOAs) and frequency differences of arrival (FDOAs) in the presence of sensor position and velocity errors. First, the explicit Cramér–Rao bound (CRB) expression for joint estimation of source and sensor positions and velocities is derived under the Gaussian noise assumption. Subsequently, we compare the localization accuracy when multiple-source positions and velocities are determined jointly and individually based on the obtained CRB results. The performance gain resulted from multiple-target cooperative positioning is also quantified using the orthogonal projection matrix. Next, the paper proposes a new estimator that formulates the localization problem as a quadratic programming with some indefinite quadratic equality constraints. Due to the non-convex nature of the optimization problem, an iterative constrained weighted least squares (ICWLS) method is developed based on matrix QR decomposition, which can be achieved through some simple and efficient numerical algorithms. The newly proposed iterative method uses a set of linear equality constraints instead of the quadratic constraints to produce a closed-form solution in each iteration. Theoretical analysis demonstrates that the proposed method, if converges, can provide the optimal solution of the formulated non-convex minimization problem. Moreover, its estimation mean-square-error (MSE) is able to reach the corresponding CRB under moderate noise level. Simulations are included to corroborate and support the theoretical development in this paper.     

A new neural network technique for the design of multilayered microwave shielded bandpass filters

In this work, we propose a novel technique based on neural networks, for the design of microwave filters in shielded printed technology. The technique uses radial basis function neural networks to represent the non linear relations between the quality factors and coupling coefficients, with the geometrical dimensions of the resonators. The radial basis function neural networks are employed for the first time in the design task of shielded printed filters, and permit a fast and precise operation with only a limited set of training data. Thanks to a new cascade configuration, a set of two neural networks provide the dimensions of the complete filter in a fast and accurate way. To improve the calculation of the geometrical dimensions, the neural networks can take as inputs both electrical parameters and physical dimensions computed by other neural networks. The neural network technique is combined with gradient based optimization methods to further improve the response of the filters. Results are presented to demonstrate the usefulness of the proposed technique for the design of practical microwave printed coupled line and hairpin filters. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Optimization techniques for the efficient design of low‐cost satellite filters considering new light materials

In this article a suitable combination of design techniques is used to efficiently design low‐cost satellite waveguide filters with rounded corners of large radius because of milling with low tolerances. Three filters have been manufactured using a magnesium body, which is lighter than the aluminium presently used in the space industry. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

On the existence of the nonlinear weighted least squares estimate for a three-parameter Weibull distribution

The problem of nonlinear weighted least squares fitting of the three-parameter Weibull distribution to the given data (w_i,t_i,y_i), i=1,…,n, is considered. The part w_i>0 of the data stands for the data weights. It is shown that the best least squares estimate exists provided that the data satisfy just the following two natural conditions: (i) 0<t₁<t₂<?<t_n and (ii) 0<y₁<y₂<?<y_n<1. To support this, an illustrative numerical example is given.     

Per-layer transmit and receive filters design for Tomlinson-Harashima precoding in multiuser MIMO systems

In this paper,the per-layer design for Tomlinson-Harashima precoding (THP) in the downlink of multiuser multiple-input multiple-output (MIMO) systems is investigated.In these systems,the number of the receivers is equal to that of the transmit antennas.Based on the criterion of maximum system sum-capacity,we study two per-layer joint transmit and receive filters design schemes with receive antenna beamforming (RAB) and receive antenna selection (RAS),respectively.Moreover,the differences of the equivalent channel gains and capacities between these two schemes are analyzed theoretically.Simulation results show that by these per-layer schemes,the system sum-rate is improved significantly with respect to the per-user processing scheme.     

Miniaturized planar filters exhibiting flexible placement of three transmission zeros suitable for duplexer design

In this work, we show that a stub‐loaded open‐loop double resonator filter can produce three transmission zeros at finite frequencies close to the passband when designed using our proposed asymmetric feed point topology. We demonstrate that by selecting the length of the stub, the placement of double transmission zeros on either the high side of the passband or the low side of the passband can be selected. This selection can be achieved by using a single design parameter: the stub length. The flexibility in the double zero placement makes these filters particularly advantageous for duplexer designs. Two duplexers are fabricated using the proposed filter topology in a microstrip on a duroid substrate and substrate‐embedded stripline via Low‐Temperature Cofired Ceramic technology (LTCC). The measurements show steep attenuation of approximately 30 dB, close to the filters' passband as well as a compact size down to 0.075λ × 0.17λ.     

Developing a design support system for the exterior form of running shoes using partial least squares and neural networks

The function of sport shoes is to improve sport performance and reduce sports-related injuries. They are commercial products developed by combining sports technology and marketing activities. Numerous studies on research and development, material application, production process improvements, and human physiological measurements for the sport shoe market exist. However, few studies have conducted an in-depth investigation on the design of forms and external appearance for sports shoes.     

An iterative design procedure for the synthesis of generalized dual‐bandpass filters

This article presents an iterative design technique to calculate the optimal position of transmission zeros in dual‐bandpass filters. In the proposed design technique, the characteristic function of the filter is linearized around the displacement of the transmission zeros. A linear system is then obtained and solved in combination with a damping technique used to guarantee the convergence. Design examples which demonstrate the efficiency of the proposed method are presented and an experimental verification at 4 GHz using open‐loop resonators validates the methodology. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Microcomputer program for the design of digital filters

The program presented here is intended to be a design device and learning tool for digital filters. Digital filters designed with the program can be implemented by incorporation within the data analysis programs of the user. The program is written in BASIC for use with the IBM-PC, is intended to be user-friendly, and includes a great deal of filter assistance not found in other programs. An example of program use shows how one filter can be used to remove noise from respiratory waveform data.     

Hierarchical Newton and least squares iterative estimation algorithm for dynamic systems by transfer functions based on the impulse responses

This paper develops a parameter estimation algorithm for linear continuous-time systems based on the hierarchical principle and the parameter decomposition strategy. Although the linear continuous-time system is a linear system, its output response is a highly nonlinear function with respect to the system parameters. In order to propose a direct estimation algorithm, a criterion function is constructed between the response output and the observation output by means of the discrete sampled data. Then a scheme by combining the Newton iteration and the least squares iteration is builded to minimise the criterion function and derive the parameter estimation algorithm. In light of the different features between the system parameters and the output function, two sub-algorithms are derived by using the parameter decomposition. In order to remove the associate terms between the two sub-algorithms, a Newton and least squares iterative algorithm is deduced to identify system parameters. Compared with the Newton iterative estimation algorithm without the parameter decomposition, the complexity of the hierarchical Newton and least squares iterative estimation algorithm is reduced because the dimension of the Hessian matrix is lessened after the parameter decomposition. The experimental results show that the proposed algorithm has good performance.     

On the equivalence of least costly and traditional experiment design for control

In this paper we establish the equivalence between least costly and traditional experiment design for control. We consider experiment design problems for both open and closed loop systems. In open loop, equivalence is established for three specific cases, relating to different parametrisations of the covariance expression (i.e. finite and high order approximations) and model structure (i.e. dependent and independently parameterised plant and noise models). In the closed loop setting, we consider only finite order covariance expressions. H_∞ performance specifications for control are used to determine the bounds on the covariance expression for both the open and closed loop cases.     

A methodology for design of multilayer microwave circuits

This paper reviews and extends the design procedures developed recently for a broad class of multilayer microwave circuits such as couplers, filters, and baluns. Multilayer configurations are now becoming increasingly popular at microwave frequencies due to the several advantages over single-layer configurations. However, systematic design procedures for implementing multilayer circuits have not been available. Examples of multilayer circuits are presented for verifying the extended design procedures. The design procedure reported earlier for coupled line multilayer filters in a homogeneous dielectric substrate environment has been extended to inhomogeneous multilayered microstriplike configurations. Modified procedure is verified by comparing the results with a full-wave electromagnetic simulation. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 455–473, 1998