On the construction of transitional filter nomographs

The construction of nomographs for transitional classical filters is described. Gain functions of classical filters are related to filter requirements resulting in a formulation for the general gain nomograph. The transitional filters that are products of approximating polynomials are incorporated into the general gain nomograph resulting in transitional filter nomographs that are sums of the individual nomographs. Nomographs for transitional filters using alternative forms where poles are interpolated are also considered. The resulting nomographs allow for quick optimization of transitional filter frequency response in many cases. Design examples are submitted and discussed. The proposed transitional filter nomographs provide the engineer with increased insight into the selection of classical transitional filters with optimum frequency response.     

Iterated gain-based stochastic filters for dynamic system identification

We propose a novel form of nonlinear stochastic filtering based on an iterative evaluation of a Kalman-like gain matrix computed within a Monte Carlo scheme as suggested by the form of the parent equation of nonlinear filtering (Kushner–Stratonovich equation) and retains the simplicity of implementation of an ensemble Kalman filter (EnKF). The numerical results, presently obtained via EnKF-like simulations with or without a reduced-rank unscented transformation, clearly indicate remarkably superior filter convergence and accuracy vis-à-vis most available filtering schemes and eminent applicability of the methods to higher dimensional dynamic system identification problems of engineering interest.     

Nomographs and filters

This paper presents the nomographs for additional classical filters, including ultraspherical, Legendre, modified associated Legendre, Papoulis, Halpern, Bessel, Gaussian, and synchronously-turned. It also identifies inaccuracies in the earlier nomographs. The basic theory of nomographs and their utilization in developing filter nomographs is presented.     

Approximate lower bound for the SNR of matched filters

For the simple binary detection problem of detecting a known signal in the presence of additive noise, the matched filter is well known to yield the highest output signal-to-noise ratio (SNR). When the detection is carried out in discrete time, selecting an optimal filter length for a specific detection problem is important. Bounds on the SNR of the matched filter can assist in this selection. Exact bounds on the SNR can be computed in terms of the eigenvalues of the noise covariance matrix, but these bounds can be difficult to compute. An approximate lower bound for the SNR has been suggested recently by Martinez and Thomas (see Ref. (2), Franklin Inst. Vol. 321, No. 5, pp. 251–260, 1986). A supplement to this bound which is more accurate for small values of filter length is discussed in this paper. Some examples which delineate a comparison between the two approximate bounds are presented.     

Optimum non-linear Wiener filters

General conditions are given for the optimality of non-linear Wiener filters which minimize the mean-square difference between the desired and actual filter outputs. These conditions, which are a generalization of the Wiener–Hopf equation are applied to the Gaussian case and the kernels of the optimum realizable and unrealizable systems are derived.     

设备更新经典问题经典性解法的再辨析

多个学科如工程经济、技术经济以及管理会计中都会论及到关于是继续使用旧设备还是对其进行更新的案例，然而不同学科甚至不同学者对其解法却有不同的观点。赵国杰教授在其著作中针对工程经济学的经典性解法提出质疑，并相应提出了基于供求均衡原则的新方法。本文通过分析认为新方法提出的疑问是多余的，而且新方法的解法是不合理的，最后得出原经典性解法仍然经典的结论。     

System functions for 2D linear phase frequency sampling filters

In this paper, four frequency sampling filter system functions which are classified as Type 1-1, Type 1-2, Type 2-1 and Type 2-2, are developed. Each type of these frequency sampling filter interpolates a frequency response through a specific set of frequency samples and also uses these frequency samples as coefficients in each of their implementations. Each of these system functions are further developed for 2D linear phase filters that have real impulse responses and for 2D linear phase filters that have real impulse responses and fourfold symmetry. The approximate conditions for which these frequency sampling filters can implement narrowband 2D linear phase filters and narrowband 2D linear phase filters with fourfold symmetry more efficiently than direct convolution filters are also derived.     

适用于海事卫星终端的体声波滤波器设计

近年来,国际海事卫星应用范围的扩展对终端设备的微型化与抗噪性提出了更高的要求,薄膜体声波滤波器成为人们关注的焦点。相对于传统滤波器,体声波滤波器具有更高的谐振频率和温度稳定性,更低的损耗和成本,同时可以实现芯片集成。本文介绍了FBAR体声波滤波器的工作原理与设计模型,在此基础上设计出了适用于BGAN下行频段的窄带滤波器。为实现材料参数的实时调整,本文采用Mason模型,通过改变串并联单元级数与面积比,最终设计出滤波器频带为1525~1559Mhz,带外抑制60dB,插损4.3dB。     

Transient responses of m-derived filters

The analytic expressions of the unit-impulse and the unit-step responses ofthe classical m-derived and the composite filters are derived. The equations have been computed by means of an IBM 360 Model 44 digital computer. Normalized curves of the unit-step response are presented. They are completely universal and can be applied to specific situations by rescaling the axes.     

TUT and TABU transitional filters

Transitional XY filters (TXY) are considered with characteristics that vary smoothly from those of filter X to those of filter Y as a parameter is varied continuously. Emphasis is placed on transitional ultraspherical—Thomson (TUT) filters and transitional ultraspherical “a”-ultraspherical “b” (TABU) filters.     

Event-triggered optimal and suboptimal distributed Kalman consensus filters for sensor networks

This paper studies the distributed Kalman consensus filtering problem based on the event-triggered (ET) protocol for linear discrete time-varying systems with multiple sensors. The ET strategy of the send-on-delta rule is employed to adjust the communication rate during data transmission. Two series of Bernoulli random variables are introduced to represent the ET schedules between a sensor and an estimator, and between an estimator and its neighbor estimators. An optimal distributed filter with a given recursive structure in the linear unbiased minimum variance criterion is derived, where solution of cross-covariance matrix (CCM) between any two estimators increases the complexity of the algorithm. In order to avert CCM, a suboptimal ET Kalman consensus filter is also presented, where the filter gain and the consensus gain are solved by minimizing an upper bound of filtering error covariance. Boundedness of the proposed suboptimal filter is analyzed based on a Lyapunov function. A numerical simulation verifies the effectiveness of the proposed algorithms.     

量子纠缠和经典热光的关联成像

关联成像理论和实验证明了光可以用特殊的方式传递经典信息文章中将介绍纠缠光和热光的关联成像实验．并从理论上分析经典热光源和双光子纠缠源在关联性质上的差异。     

Rational approximation of three-dimensional digital filters

Two techniques are developed for approximating a given three-dimensional (3-D) digital filter by a 3-D rational function. The one is by a general 3-D rational function and the other by a 3-D rational function which is separable in the denominator. Each technique relies on the use of mixed first and second information, in the form of a finite portion of the impulse response and its autocorrelation sequence. The approximation is performed by solving a set of linear equations. The separable-denominator approximation is more advantageous due to the guaranteed stability and reduced amount of calculations.     

Block implementation of two-dimensional digital filters

A novel principle known as block transformation is developed for the block implementation of two-dimensional (2-D) digital filters. It employs the one-dimensional (1-D) block implementation concept forwarded by Burrus (7) as a basic tool. Using this block transformation principle three distinct forms of 2-D block equations are derived. The generalized nature of the approach presented here facilitates the straightforward extension of this technique to higher dimensional digital filters.     

Phase segregation of polymerizable lipids to construct filters for separating lipid-membrane-embedded species

Supported lipid bilayer (SLB) platforms have been developed to transport and separate membrane-embedded species in the species'' native bilayer environment. In this study, we used the phase segregation phenomenon of lipid mixtures containing a polymerizable diacetylene phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DiynePC), and a nonpolymerizable phospholipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), to create filter barrier structures in SLBs. Upon exposing the phase segregated samples to UV light, the DiynePC-rich domains could become crosslinked and remain fixed on the surface of the support, while the DOPC-rich regions, where no crosslinking could happen, could be removed later by detergent washing, and thus became the void regions in the filter. During the filter fabrication process, we used the laminar flow configuration in a microfluidic channel to control the spatial locations of the feed region and filter region in the SLB. The flow in a microfluidic channel was also used to apply a strong hydrodynamic shear stress to the SLB to transport the membrane-embedded species from the feed region to the filter region. We varied the DiynePC/DOPC molar ratio from 60/40 to 80/20 to adjust the cutoff size of the filter barriers and used two model membrane-embedded species of different sizes to examine the filtering capability. One of the model species, Texas Red 1,2-dihexa-decanoyl-sn-glycero-3-phosphoethanolamine triethylammonium salt (Texas Red DHPE), had a single-lipid size, and the other species, cholera toxin subunit B-GM1 complex, had a multilipid size. When the DiynePC/DOPC molar ratio was 60/40, both species had high penetration ratios in the filter region. However, when the ratio was increased to 70/30, only the Texas Red DHPE, which was the smaller of the two model species, could penetrate the filter to a considerable extent. When the ratio was increased to 80/20, neither of the model species could penetrate the filter region. The results showed the possibility of using phase segregation of a mixture containing a polymerizable lipid and a nonpolymerizable lipid to fabricate filter barrier structures with tunable cutoff sizes in SLBs.