Low Coefficient Sensitivity Research Articles

The effectiveness of intervention measures on MERS-CoV transmission by using the contact networks reconstructed from link prediction data.

Mitigating the spread of infectious diseases is of paramount concern for societal safety, necessitating the development of effective intervention measures. Epidemic simulation is widely used to evaluate the efficacy of such measures, but realistic simulation environments are crucial for meaningful insights. Despite the common use of contact-tracing data to construct realistic networks, they have inherent limitations. This study explores reconstructing simulation networks using link prediction methods as an alternative approach. The primary objective of this study is to assess the effectiveness of intervention measures on the reconstructed network, focusing on the 2015 MERS-CoV outbreak in South Korea. Contact-tracing data were acquired, and simulation networks were reconstructed using the graph autoencoder (GAE)-based link prediction method. A scale-free (SF) network was employed for comparison purposes. Epidemic simulations were conducted to evaluate three intervention strategies: Mass Quarantine (MQ), Isolation, and Isolation combined with Acquaintance Quarantine (AQ + Isolation). Simulation results showed that AQ + Isolation was the most effective intervention on the GAE network, resulting in consistent epidemic curves due to high clustering coefficients. Conversely, MQ and AQ + Isolation were highly effective on the SF network, attributed to its low clustering coefficient and intervention sensitivity. Isolation alone exhibited reduced effectiveness. These findings emphasize the significant impact of network structure on intervention outcomes and suggest a potential overestimation of effectiveness in SF networks. Additionally, they highlight the complementary use of link prediction methods. This innovative methodology provides inspiration for enhancing simulation environments in future endeavors. It also offers valuable insights for informing public health decision-making processes, emphasizing the importance of realistic simulation environments and the potential of link prediction methods.

Sparse FIR Filter Design With k-Max Sparsity and Peak Error Constraints

FIR filters have boosted the development of digital signal processing, beamformers, and so on, due to their stability and low coefficient sensitivity. Generally, the design of FIR filters follows two main principles, i.e., the specification on the response error and the low implementation complexity. In this brief, we describe the sparsity of the filter coefficients using the k-maximum function, which equals to <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -norm under mild conditions and has no restriction on the magnitude of nonzero coefficients. In order to avoid possible violation of specifications on response errors caused by frequency discretization, we estimate the frequencies at which the magnitude of the response error is maximized when constructing linear problems in the proposed algorithm. To address the nonlinearity and nonconvexity of the resulted optimization problem, we transform it into a piecewise linear concave optimization (PLCO) problem. Considering the fact that a PLCO problems is reduced to a linear programming (LP) problem locally, we outline an iterative algorithm by solving a series of LP problems and provide a brief complexity analysis. Numerical experiments on the propose method and some state-of-the-art methods are performed, the result of which shows the excellent performance of the propose method on balancing the sparsity and computational efficiency.

Low temperature coefficient and low line sensitivity subthreshold curvature‐compensated voltage reference

SummaryA high‐order curvature‐compensated subthreshold voltage reference is proposed in this paper. The proposed curvature‐compensated voltage reference consists of two supply‐independent first‐order voltage references and a curvature compensation circuit. The supply‐independent first‐order voltage reference uses a negative feedback loop which improves the line sensitivity and eliminates the demand of operational amplifier, whereas the curvature compensation circuit provides high‐order temperature‐compensated output reference voltage. The proposed curvature‐compensated voltage reference provides an output reference voltage of 118.54 mV with a temperature coefficient of 21.5 ppm/°C over a wide temperature range of −60°C to 120°C. The power supply rejection ratio and line sensitivity are observed as −68.64 dB (for the frequency range of 1 Hz to 100 Hz) and 0.035%/V (for the supply voltage varies from 0.85 V to 2.5 V), respectively. The values of output noise at the frequencies of 1 kHz and 10 kHz without using any capacitive filter are obtained as 179.13 nV/ √ Hz and 123.87 nV/ √ Hz, respectively.

A Class of IIR Filters Synthesized Using Frequency-Response Masking Technique

This letter presents a class of infinite impulse response (IIR) filters synthesized using a system of IIR subfilters based on the frequency-response masking (FRM) technique. In the proposed class of filters, the bandedge shaping filters are a parallel connection of two allpass filters, and the masking filters are approximately linear phase IIR filters composed of a parallel connection of a delay line and an allpass filter. A design method which jointly optimizes the IIR subfilters is introduced. The proposed class of IIR filters has lower coefficient sensitivity and roundoff noise compared with conventional IIR filters.

Design of Narrow Transition Band Digital Filter: An Analytical Approach

Frequency response masking (FRM) approach, is widely used to reduce the transition width of FIR filter which includes several advantages like lower coefficient sensitivity, higher computation speed and low power consumption. This paper proposes a novel interpolated bandpass method (IBM) for the synthesis of linear phase, narrow transition band FIR filter with less complexity. Simulation results have shown the magnitude response of several lowpass FIR filters with narrow transition bandwidth, as designed with the aid of proposed approach. Supremacy of the proposed algorithm has also been established in terms of frequency response characteristics and hardware complexity over a number of state-of-the-art techniques of recent interest. Simulation results have identified an improvement of ∼18.89%, 44.62%, 38.75%, 41.2% and 29.5% in terms of transition bandwidth when compared with several example filters under consideration. In addition to this, hardware cost resulting from the proposed narrow-band FIR filter is analyzed by implementing it on Artix field programmable gate array (FPGA) chip and consequently power consumption of the resulting filter has been estimated using Xilinx Power Estimator (XPE)-2018.1. Finally, the designed narrow transition band FIR filter is used in filtered-orthogonal frequency division multiplexing (F-OFDM) based quadrature amplitude modulated (QAM) system and the resultant bit error rate (BER) performance has been studied.

On the Passivity of Wave Digital Networks

With inventing the wave digital (WD) filters almost fifty years ago, Alfred Fettweis laid the foundation to a completely new approach for the digital modeling of passive analog filter circuits. Soon it became clear that not only classical filter structures could be modeled by the WD concept, but also other linear and nonlinear electrical circuits and, moreover, even general physical systems, including those being described by partial differential equations. Of particular significance is the fact that this approach makes it possible to transfer the important physical concepts of passivity and losslessness from the analog to the digital domain. As a result, properly designed passive WD filters exhibit a very low coefficient sensitivity which considerably reduces the hardware requirements. This is clearly one important issue of the WD concept. However, even more important are the excellent stability properties which can be achieved by applying the concepts of passivity and incremental passivity. In this paper a review of these latter properties and its consequences will be presented. It will in particular be discussed how the passivity can be preserved even under finite arithmetic conditions.

Design and FPGA implementation of multiplierless comb filter

SummaryThe main objective of this paper is to design and implement minimum multiplier, low latency structures of a comb filter. Multipliers are the most area and power consuming elements; therefore, it is desirable to realize a filter with minimum number of multipliers. In this paper, design of comb filters based on lattice wave digital filters (LWDF) structure is proposed to minimize the number of multipliers. The fundamental processing unit employed in LWDF requires only one multiplier. These lattice wave digital comb filters (LWDCFs) are realized using Richards' and transformed first‐order and second‐order all‐pass sections. The resulting structural realizations of LWDCFs exhibit properties such as low coefficient sensitivity, high dynamic range, high overflow level, and low round‐off noise. Multiplier coefficients of the proposed structures are implemented with canonic signed digit code (CSDC) technique using shift and add operations leading to multiplierless implementation. This contributes in reduction of number of addition levels which reduces the latency of the critical loop. A field programmable gate array (FPGA) platform is used for evaluation and testing of the proposed LWDCFs to acquire advantages of the parallelism, low cost, and low power consumption. The implementation of the proposed LWDCFs is accomplished on Xilinx Spartan‐6 and Virtex‐6 FPGA devices. By means of examples, it is shown that the implementations of the proposed LWDCFs attain high maximum sampling frequency, reduced hardware, and low power dissipation compared with the existing comb filter structures. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Multiplierless Multiple-Stage Cascaded FIR Filter Design

It is well known that multiplierless finite impulse response (FIR) filters in multiple-stage cascade form can achieve lower hardware cost and lower coefficient sensitivity than that of single stage design. In this work, a novel algorithm is proposed for the design of multiplierless multiple-stage cascaded FIR filters. Unlike to the conventional algorithms in which the number of stages is fixed and usually is fixed to two, the number of stage in the proposed algorithm is automatically determined. The design examples show that the proposed algorithm significantly outperforms the best existing algorithm in terms of hardware cost and the design time is also saved.

General formulation of shift and delta operator based 2-D VLSI filter structures without global broadcast and incorporation of the symmetry

Having local data communication (without global broadcast of signals) among the elements is important in very large scale integration (VLSI) designs. Recently, 2-D systolic digital filter architectures were presented which eliminated the global broadcast of the input and output signals. In this paper a generalized formulation is presented that allows the derivation of various new 2-D VLSI filter structures, without global broadcast, using different 1-D filter sub-blocks and different interconnecting frameworks. The 1-D sub-blocks in z-domain are represented by general digital two-pair networks which consist of direct-form or lattice-type FIR filters in one of the frequency variables. Then, by applying the sub-blocks in various frameworks, 2-D structures realizing different transfer functions are easily obtained. As delta discrete-time operator based 1-D and 2-D digital filters (in $$\gamma $$ -domain) were shown to offer better numerical accuracy and lower coefficient sensitivity in narrow-band filter designs when compared to the traditional shift-operator formulation we have covered both the conventional z-domain filters as well as delta discrete-time operator based filters. Structures realizing general 2-D IIR (both z- and $$\gamma $$ -domains) and FIR transfer functions (z-domain only) are presented. As symmetry in the frequency response reduces the complexity of the design, IIR transfer functions with separable denominators, and transfer functions with quadrantal magnitude symmetry are also presented. The separable denominator frameworks are needed for quadrantal symmetry structures to guarantee BIBO stability and thus presented for both the operators. Some limitations of having exact symmetry with separable 1-D denominator factors are also discussed.

Design of Discrete-Valued Linear Phase FIR Filters in Cascade Form

Digital filters in cascade form enjoy many advantages over their equivalent single-stage realizations in that lower coefficient sensitivity, higher throughput, reduced computational and smaller implementation cost can be achieved. However, the numerical design and optimization of such structure are of much more difficulty than the single-stage case if the filter coefficients are restricted to be of discrete values. This is mainly due to the non-convexity of the constraints, which rules out the possibility of employing sophisticated convex optimization techniques as well as the guaranteed global optimality. In this work, a general-purpose algorithm is proposed for the design of linear phase finite impulse response (FIR) filters in cascade form with discrete coefficients. The proposed algorithm decomposes the overall filter into subfilters during the traverse of a tree search of the overall filter. Discrete-valued linear phase FIR filters are able to be searched and decomposed into both symmetric and non-symmetric subfilters. The optimization complexity is of the same order as the single-stage filter optimization. Design examples have shown that the proposed algorithm is capable of achieving notable reduction in both implementation cost and adder depth compared with their single-stage optimum designs.

Unified theory of symmetry for two-dimensional complex polynomials using delta discrete-time operator

The complexity in the design and implementation of 2-D filters can be reduced considerably if the symmetries that might be present in the frequency responses of these filters are utilized. As the delta operator (?-domain) formulation of digital filters offers better numerical accuracy and lower coefficient sensitivity in narrow-band filter designs when compared to the traditional shift-operator formulation, it is desirable to have efficient design and implementation techniques in ?-domain which utilize the various symmetries in the filter specifications. Furthermore, with the delta operator formulation, the discrete-time systems and results converge to their continuous-time counterparts as the sampling periods tend to zero. So a unifying theory can be established for both discrete- and continuous-time systems using the delta operator approach. With these motivations, we comprehensively establish the unifying symmetry theory for delta-operator formulated discrete-time complex-coefficient 2-D polynomials and functions, arising out of the many types of symmetries in their magnitude responses. The derived symmetry results merge with the s-domain results when the sampling periods tend to zero, and are more general than the real-coefficient results presented earlier. An example is provided to illustrate the use of the symmetry constraints in the design of a 2-D IIR filter with complex coefficients. For the narrow-band filter in the example, it can be seen that the ?-domain transfer function possesses better sensitivity to coefficient rounding than the z-domain counterpart.

Guest Editorial: Low-Power Digital Filter Design Techniques and Their Applications

Welcome to this Special Issue on Low-Power Digital Filter Design Techniques and Their Applications. Digital filters are essential elements of many signal processing systems and everyday electronics such as radios, cell phones, and biomedical devices. With the ever-increasing popularity of portable devices in communication, medical, and audio/video systems, the computational efficiency and power consumption of digital filters have become increasingly a matter of concern, as digital filters usually involve a large number of arithmetic operations, especially for the finite impulse response (FIR) filters. While FIR filters do have merits in stability, linear phase property, and low coefficient sensitivity, they consume more power than their infinite impulse response (IIR) equivalents in general. There has been consistent effort to develop low-power techniques for FIR filters in the past half century, such as multirate filtering, subfilter approaches, and multiplierless filtering. In multirate filtering, arithmetic units are shifted to the lower frequency end, resulting in reduced power at low operation frequencies. In subfilter approaches, filters are connected in series and/or parallel to form a network, where the frequency responses of different frequency intervals are taken care of by different filters or filter pairs. The overall number of non-trivial coefficients can be significantly reduced by cleverly arranging the subfilters. A very successful subfilter structure is the frequency-response masking (FRM) structure, which was first proposed in 1986 by Y.C. Lim. In 1979 Lim pioneered multiplierless filter-

Evolutionary synthesis of low-sensitivity digital filters using adjacency matrix

An evolutionary synthesis method to generate digital filters with low coefficient sensitivity is presented. The method uses a chromosome coding based on the graph adjacency matrix representation. It is shown that the proposed chromosome representation enables to easily verify and avoid the generation of topologically invalid and non-computable individuals during the evolutionary process. The efficiency of the proposed algorithm is tested in the synthesis of two low-pass digital filters and the results are compared with other examples found in the literature.

Symmetry Study for Delta- Operator-Based 2-D Digital Filters

The complexity in the design and implementation of two-dimensional (2-D) filters can be considerably reduced if we utilize the symmetries that might be present in the frequency response of these filters. As the delta-operator formulation of digital filters offers better numerical accuracy and lower coefficient sensitivity in narrowband filter designs when compared to the traditional shift-operator formulation, it is desirable to have efficient design and implementation techniques in gamma-domain which utilize the various symmetries in filter specifications. With this motivation, we comprehensively establish the theory of constraints for delta-operator formulated discrete-time real-coefficient polynomials and functions, arising out of the many types of symmetries in their magnitude responses. We also show that as sampling time tends to zero, the gamma-domain symmetry constraints merge with those of s-domain symmetry constraints. We then present a least square error criterion based procedure to design 2-D digital filters in gamma-domain that utilizes the symmetry properties of the magnitude specification. A design example is provided to illustrate the savings in computational complexity resulting from the use of the gamma-domain symmetry constraints

Evolutionary synthesis of digital filter structures using genetic programming

This paper presents a synthesis method for infinite-impulse response (IIR) digital filter structures using genetic programming with automatically defined functions (GP-ADF). In the proposed method, digital filter structures are represented as S-expressions with subroutines, which are written directly from the set of difference equations. This paper also shows the condition for the constructing the S-expressions that represent the filter structures without delay-free loops. Numerical examples synthesize two-filter structures: the low-coefficient sensitivity fourth-order filter structure and the low-output roundoff noise second-order filter structure.

Heuristic synthesis of low coefficient sensitivity second-order digital filters using genetic programming

The authors propose a new approach to the synthesis of low coefficient sensitivity second-order digital filter sections using genetic programming (GP). GP is applied to the synthesis problem by establishing a mapping between the filter structures and computer programs. Genetic operators change the computer programs in order to change the connections between the elements in the filter structures, and consequently change the coefficient sensitivities of those filter structures. The fitness measure that includes the coefficient sensitivities enables the selection operator to choose low sensitivity filter structures. In the paper, two coefficient sensitivity measures are used: the magnitude sensitivity and the relative sensitivity. A numerical example is presented to demonstrate that the sensitivity of the filter synthesised by GP is lower than that of other low coefficient sensitivity filter structures proposed so far.

DETERMINATION OF CYCLAMATE RADICAL BY SINGLE-COLUMN ION-CHROMATOGRAPHY WITH A BULK ACOUSTIC WAVE DETECTOR

A chromatographic method based on a combination of single-column ion-chromatography separation with a bulk-acoustic-wave double-cell quartz crystal (DCQC) detector quantification for the determination of cyclamate in foodstuffs and body fluids was developed. The chromatographic system involves the use of a Shimadzu IC-A1 column with 5mM o-phthalic acid/methanol (90:10 V/V) as a mobile phase. The method exhibits an acceptable detection limit and anti-interference ability. The DCQC detector has a low temperature coefficient and high conductance sensitivity. Foodstuff and body fluid sample such as ice cream, beverage, dried fruit of Areca catechu L., and urine were analysed successfully.

Determination of divalent carboxylic acids in traditional Chinese herbal and patent medicines using HPLC with double cell quartz crystal detector

A rapid, simple and sensitive high performance liquid chromatography (HPLC) method combined with a novel double cell quartz crystal (DCQC) detector is described for the determination of divalent carboxylic acids in traditional Chinese herbal and patent medicines. The chromatographic system involves the use of a μBondapak-NH 2 column with 20 mM KH 2PO 4 (pH 3.4, adjusted by H 3PO 4)/acetonitrile (95:5%) as a mobile phase. The DCQC detector has a low temperature coefficient and high conductance sensitivity independent of the background from 7.2 to 2500 μS. Analysis of sample is completed without the use of an ion suppression device.

Synthesis of low-sensitivity second-order digital filters using genetic programming with automatically defined functions

This letter proposes a synthesis method for low coefficient sensitivity second-order IIR digital filter structures using genetic programming with automatically defined functions (GP-ADF). In this letter, digital filter structures are represented as S-expressions with subroutines. It is easy to generate syntactically valid S-expressions and perform the genetic operations, because the representation is suitable for GP. A numerical example uses the fitness measure, including the magnitude sensitivity, and demonstrates that the proposed method can synthesize efficiently very low coefficient sensitivity filter structures.

Design of very low-sensitivity and low-noise recursive filters using a cascade of low order lattice wave digital filters

Among the best structures for implementing recursive digital filters are lattice wave digital (LWD) filters (parallel connections of two all-pass filters). They are characterized by many attractive properties, such as a reasonably low coefficient sensitivity, a low roundoff noise level, and the absence of parasitic oscillations. The main drawback is that if the stopband attenuation is very high, then many bits are required for the coefficient representations. In order to get around this problem, a structure consisting of a cascade of LWD filters is introduced in this paper. The main advantage of the proposed structure, compared with the direct LWD filter, is that the poles of the new structure are further away from the unit circle. Consequently, the number of bits required for both the data and coefficient representations are significantly reduced. The price paid for these reductions is a slight increase in the overall filter order. By properly selecting the number of LWD filters and their orders and optimizing them, their coefficients are implementable by using a few powers of two. Filters of this kind are very attractive in very large-scale integration (VLSI) implementations, where a general multiplier is very costly.