A novel current-mode second-order notch filter configuration employing single CDBA and reduced number of passive components

A novel current-mode second-order notch filter configuration is proposed. The presented circuit uses single current differencing buffered amplifier (CDBA) and minimum passive components. High output impedance of the proposed filter enables the circuit to be cascaded without requiring any impedance matching device. It has also low passive sensitivities. The theoretical results are verified with PSPICE simulations.     

一种新型CMOS电流控制电流传输器

提出了一种基于共源共栅电流镜的CMOS电流控制电流传输器(CCCⅡ)电路。该电路由跨导线性环电路和共源共栅电流镜构成。相对于基于基本电流镜的CMOS电流控制电流传输器,该电路具有输出阻抗更大以及电流传输精度更高的优点。分析了电路的工作原理,给出了实验结果,验证了电路的正确性。     

Multi-input single-output filter with reduced number of passive elements employing single current conveyor

A new biquadratic universal filter configuration realising second-order low-pass, band-pass, and high-pass functions employing single current conveyor is proposed. Using this configuration high-pass, low-pass and band-pass filters can be realized with little modifications. The circuit employs a second-generation current conveyor (CCII+), and only four passive components. Since the current conveyor is a high performance active element, the circuit proposed is suitable for wide band applications. The derived filters can be easily cascaded and use reduced number of passive components compared to previously reported counterparts. To illustrate the design possibilities provided by the introduced circuit current mode multifunction filters are constructed and tested.     

电流控制电流传输器的温度补偿技术

针对于目前CMOS电流控制电流传输器(CCCII)中普遍存在的温度依赖性问题,提出一个新的温度补偿技术。这种技术主要使用电流偏置电路和分流电路为CCCII产生偏置电流,其中偏置电路中的电流和μC′OX成正比。基于0.5μm CMOS工艺参数,运用HSPICE仿真软件,对提出的电路进行仿真,仿真结果验证了电路的正确性。     

采用电流传输器实现低通滤波器的精确补偿及仿真

以一个用第二代电流传输器（ＣＣＩＩ） 实现三阶低通滤波器的例子来分析电路工作在非理想状态下的精确补偿方式,并进行计算机仿真,最后得出补偿后该电路具有有源低灵敏度的结论     

模拟滤波器的数字化

从分析硬件模拟滤波器电路原理图开始,利用MatLab计算滤波器参数,将硬件滤波器数字化、软件化;给出了滤波器的C伪代码,并验证了硬件滤波器和导出的软件滤波器特性的一致性。     

基于匹配滤波技术的特征信号提取的仿真和实现

激光测高仪的回波信号中包含目标物的粗糙度、倾斜度、反射率等信息,对于复杂地物特征的回波信号,采用多通道匹配滤波技术不仅可以获得高的信噪比,还可以保证信号的保真度。     

改进的Gabor滤波算法及其在FPGA中的实现

针对指纹图像核心区域方向变化剧烈及用软件实现图像增强速度慢的缺点,提出了一种适应于硬件并行处理的基于改进的Gabor滤波的指纹图像增强算法,并用硬件描述语言在可编程逻辑门阵列(FPGA)上实现,同时介绍了系统的工作过程及总体结构.实验结果表明,改进的Gabor滤波能使图像的断裂处得到很好的连接,指纹图像信息明显增强,并且在速度方面利用硬件实现远远高于软件.实验表明,FPGA在图像处理方面满足实时性的要求,适用于图像增强的系统.     

Globalized matrix-explicit Newton-GMRES for the high-order accurate solution of the Euler equations

Implicit methods for finite-volume schemes on unstructured grids typically rely on a matrix-free implementation of GMRES and an explicit first-order accurate Jacobian for preconditioning. Globalization is typically achieved using a global timestep or a CFL based local timestep. We show that robustness of the globalization can be improved by supplementing the pseudo-timestepping method commonly used with a line search method. The number of timesteps required for convergence can be reduced by using a timestep that scales with the local residual. We also show that it is possible to form the high-order Jacobian explicitly at a reasonable computational cost. This is demonstrated for cases using both limited and unlimited reconstruction. This exact Jacobian can be used for preconditioning and directly in the GMRES method. The benefits of improvements in preconditioning and the elimination of residual evaluations in the inner iterations of the matrix-free GMRES method are substantial. Computational results focus on second- and fourth-order accurate schemes with some results for the third-order scheme. Overall computational cost for the matrix-explicit method is lower than the matrix-free method for all cases. The fourth-order matrix-explicit scheme is a factor of 1.6-3 faster than the matrix-free scheme while requiring about 50-100% more memory.     

On filter theory of residuated lattices

The aim of this paper is to develop the filter theory of general residuated lattices. First, we extend some particular types of filters and fuzzy filters in BL-algebras and MTL-algebras naturally to general residuated lattices, and further enumerate some relative results obtained in BL-algebras or MTL-algebras, which still hold in general residuated lattices. Next, we introduce the concepts of regular filters and fuzzy regular filters to general residuated lattices, which are two new types of filters and fuzzy filters, and derive some of their characterizations. Finally, we discuss the relations between (fuzzy) regular filters and several other special (fuzzy) filters, and also characterize some special classes of residuated lattices by filters or fuzzy filters.     

数控直流电流源的设计

设计并制作了一个高精度数控直流电流源。数控直流电流源的模拟控制电路部分采用串联反馈式控制方式;以AT89C52单片机为核心辅之以ZLG7289、MAX531、TLC2543、X5045等串行接口芯片构成数字控制部分。单片机实时将预置值和实测值进行比较、调整控制,提高了电流源的输出精度,经实验证明具有较高的控制精度。     

基于第三代电流传输器的滤波器设计

提出一种基于第三代电流传输器(CCⅢ)的电流模式二阶滤波器的实现方法,导出的电流模式连续时间二阶滤波器结构比较简单,可实现低通、高通、带通3种滤波。这3种滤波的无源和有源灵敏度较低。本文提出的电路基于TMSC 0.35μm CMOS工艺,在2.5V电源电压工作条件下,采用Hspice在LEVEL49模型参数下对整个电路进行仿真。     

Measurement of urea, creatinine and urea to creatinine ratio using enzyme based chemical current conveyor (CCCII+)

A system potentially capable of providing continuous analogue computation of (i) urea concentration, (ii) creatinine concentration and (iii) urea-to-creatinine ratio, important markers for the prediction of renal failure is described. The system utilises two enzyme modified chemical current-conveyors, CCCII+, to obtain the outputs directly related to the urea and creatinine concentrations. The devices have been separately prepared by immobilising urease and creatinine deiminase (CD) enzymes onto the input ISFET surfaces. The primary experimental results of the system demonstrate a linear response covering a normal physiological range of urea between 2.5 and 8.3 mM and creatinine between 44 and 106 μM. We propose that this system has the potential for real-time monitoring and suitable for medical determination for renal dysfunctionality.     

自适应陷波器在远场涡流检测中的应用

远场涡流中干扰对有用信号的影响极大 ,因此消除干扰便成为远场涡流检测的关键。提出一种用数字信号处理的技术来实现干扰的消除。同原有的模拟处理方式相比 ,具有更准确跟踪频率和可控带宽等优点。     

有源电力滤波器的鲁棒重复电流控制策略研究

针对传统的电流环PI控制存在稳态误差和相角偏移等问题,提出了一种有源电力滤波器的鲁棒重复电流控制策略,详细分析了鲁棒重复控制策略的具体实现方法。仿真和试验结果表明,该控制策略在实现有源电力滤波器输出补偿电流准确跟踪指令电流的同时,提高了有源电力滤波器的抗干扰性能,显著改善了有源电力滤波器的动静态性能。     

A cumulant-based method for the direct estimation of the spatial Wiener filter

In this paper we propose a new algorithm for performing blind source separation and signal recovery for the narrowband case. This algorithm seeks to estimate and implement the Wiener filter directly, using the second- and fourth-order cumulants. The estimated filter is asymptotically consistent with or without noise, and is not subject to the bound imposed by pre-whitening as with some existing algorithms. In many cases it nearly achieves the clairvoyant Wiener limit as performance studies show.     

Improvement of the accuracy in boundary element method based on high-order discretization

The boundary element method (BEM) is a popular method to solve various problems in engineering and physics and has been used widely in the last two decades. In high-order discretization the boundary elements are interpolated with some polynomial functions. These polynomials are employed to provide higher degrees of continuity for the geometry of boundary elements, and also they are used as interpolation functions for the variables located on the boundary elements. The main aim of this paper is to improve the accuracy of the high-order discretization in the two-dimensional BEM. In the high-order discretization, both the geometry and the variables of the boundary elements are interpolated with the polynomial function P_m, where m denotes the degree of the polynomial. In the current paper we will prove that if the geometry of the boundary elements is interpolated with the polynomial function P_m+1 instead of P_m, the accuracy of the results increases significantly. The analytical results presented in this work show that employing the new approach, the order of convergence increases from O(L₀)^m to O(L₀)^m+1 without using more CPU time where L₀ is the length of the longest boundary element. The theoretical results are also confirmed by some numerical experiments.     

On the nice behaviour of the Gaussian projection filter with small observation noise

When projecting on the manifold of Gaussian densities, the projection filter has been shown to be equal to a McShane-Fisk-Stratonovich (MFS) derivation of the Gaussian assumed density filter. Starting from this point, we study the asymptotic behaviour of the Gaussian projection filter when the covariance of the observation noise tends to zero. We prove that the mean square difference between the true state of the system and the estimate given by the projection filter is bounded by a constant which is proportional to the magnitude of the observation noise.     

On the divergence of information filter for multi sensors fusion

The paper deals with the divergence of information filter in multi sensor target tracking problem using bearing only measurements. Information filter has a number of advantages in terms of computational requirements over Kalman filter for target tracking applications. Compared to Kalman filter it also has the advantage that one can start estimation even without an initial estimate. But this filter is seen to diverge after tracking for a short period of time, even when the target is moving at a constant velocity. A technique to overcome this problem has been discussed in this paper. The information update equations of the conventional information filter are modified in terms of fuzzy function of error and change of error, and the results have been found to be encouraging. The efficacy of the technique in preventing divergence is demonstrated in the context of tracking a maneuvering target also.     

三电平有源电力滤波器模型预测电流控制方法研究

针对现有有源电力滤波器大多使用数字化控制器实现,存在系统延时的问题,提出了一种模型预测电流控制方法,并将其应用于三电平有源电力滤波器控制系统中。该方法根据实际有源电力滤波器控制系统模型设计质量函数,在每个采样周期内,对变频器27个电压矢量分别进行评估,选取使质量函数取值最小的电压矢量来控制下一周期开关导通,使有源电力滤波器的补偿电流快速跟踪参考值。仿真结果表明,该方法不仅能使有源电力滤波器实现高性能补偿,而且极大地减小了数字系统的固有延时。