Modular Filter Research Articles

A Functional Composition Approach to Filter Sharpening and Modular Filter Design

Designing and implementing systems as an interconnection of smaller subsystems is a common practice for modularity and standardization of components and design algorithms. Although not typically cast in this framework, many of these approaches can be viewed within the mathematical context of functional composition. This paper re-interprets and generalizes within the functional composition framework one such approach known as filter sharpening, i.e. interconnecting filter modules which have significant approximation error in order to obtain improved filter characteristics. More specifically, filter sharpening is approached by determining the composing polynomial to minimize the infinity-norm of the approximation error, utilizing the First Algorithm of Remez. This is applied both to sharpening for FIR, even-symmetric filters and for the more general case of subfilters that have complex-valued frequency responses including causal IIR filters and for continuous-time filters. Within the framework of functional composition, this paper also explores the use of functional decomposition to approximate a desired system as a composition of simpler functions based on a two-norm on the approximation error. Among the potential advantages of this decomposition is the ability for modular implementation in which the inner component of the functional decomposition represents the subfilters and the outer the interconnection.

Design of Vacuum‐Cleaned Dust Filters with Modular Filter Units

AbstractFor vacuum‐cleaned dust filters with a small moving suck‐off nozzle as cleaning device no calculation methods exist to determine design parameters like the needed traverse velocity of the nozzle or the filter area. A method to calculate the total filter area or the number of parallel working filter modules with fixed filter area is presented. Well‐known equations for the design of a cleanable multichamber jet‐pulse filter were modified to take into account a continuous regeneration of a vacuum‐cleaned dust filter by a suck‐off nozzle. For vacuum cleaning of the filter it was considered that the regeneration period depends on the suck‐off nozzle traverse velocity and the unique cleaning pattern and length of the suck‐off nozzle traverse pathway. An example for the calculation of the necessary number of parallel working modules for the determination of the filter area of large filter apparatus with vacuum cleaning is described.

Power-performance enhancement of two-dimensional RNS-based DWT image processor using static voltage scaling

Digital image processing is widely used in fast and high-performance applications. The high speed and functional requirements of such applications, however, lead to increased power consumption. Hence, finding a way to solve the power-performance issues is of great importance. In this paper, we present the power-performance enhancement of a two-dimensional (2D) discrete wavelet transform (DWT) image processor using the residue number system (RNS) and the static voltage scaling (SVS) scheme. The aim of this paper is to investigate the effects of the RNS and SVS scheme on the proposed image processor. The original contributions of the proposed design include a low-complexity hardware architecture of the RNS-based filter banks, optimized transposition units and exploiting the SVS scheme to reduce the power consumption. The multiplierless scheme of the RNS-based filter banks and the binary-coded number format are used to save on hardware complexity, while modular arithmetics and 6-bit dyadic fraction filter coefficients are applied to improve the system performance. The bi-orthogonal discrete wavelet transform CDF97 is chosen to compress the images due to its multi-resolution features and its ability to localize finite signals. The proposed design has been synthesized using the generic library SAED90nmEDK with the Synopsys Design Compiler (DC).

High-speed filtration using highly porous fiber media for advanced and compact particle removal

Since its recent introduction to the filtration industry, one of the major concerns about the use of fiber in water treatment has been its applicability for high-rate filtration while minimizing the build-up of headloss. In this study, a compact, modular filter employing non-woven, highly porous polypropylene fiber as filter media was investigated for the treatment of turbid water under high filtration rates. The impact of different operating variables such as polyaluminum chloride (PAC) dose and filtration rate on the effluent turbidity and headloss were investigated. Due to the fiber's high porosity, the filter was able to retain solids at a filtration rate of up to 1,500 m/day without headloss. When PAC was added, the effluent turbidity decreased significantly with the lowest observed when the dose was 1 mg/L. Furthermore, the effluent turbidity was found to increase with the filtration rate. During all the experiments, no headloss was observed except when the filtration rate was 2,250 m/day or when the PAC dose was 5 mg/L. In terms of its compactness and applicability at very high filtration rates, the polypropylene fiber filter can have a considerable advantage compared to other filters.

Reliable and low error dual modular redundancy FIR filter with wide protection window

Reliable and low error dual modular redundancy FIR filter with wide protection window

Modular filter convergence theorems for abstract sampling type operators

We study the problem of approximating a real-valued function f by considering sequences of general operators of sampling type, which include both discrete and integral ones. This approach gives a unitary treatment of various kinds of classical operators, such as Urysohn integral operators, in particular convolution integrals, and generalized sampling series.

Modular filter convergence theorems for Urysohn integral operators and applications

We prove some versions of modular convergence theorems for nonlinear Urysohn-type integral operators with respect to filter convergence. We consider pointwise filter convergence of functions giving also some applications to linear and nonlinear Mellin operators. We show that our results are strict extensions of the classical ones.

Numerical Analysis of Filter-Based Stabilization for Evolution Equations

We consider filter-based stabilization for evolution equations (in general) and for the Navier--Stokes equations (in particular). The first method we consider is to advance in time one time step by a given method and then to apply an (uncoupled and modular) filter to get the approximation at the new time level. This filter-based stabilization, although algorithmically appealing, is viewed in the literature as introducing far too much numerical dissipation to achieve a quality approximate solution. We show that this is indeed the case. We then consider a modification: Evolve one time step, filter, deconvolve, then relax to get the approximation at the new time step. We give a precise analysis of the numerical diffusion and error in this process and show it has great promise, confirmed in several numerical experiments.

A Bit-Rate Aware Scalable H.264/AVC Deblocking Filter Using Dynamic Partial Reconfiguration

In H.264/AVC, a deblocking filter improves visual quality by reducing the presence of blocking artifacts in decoded video frames. The deblocking filter accounts for one third of the computational complexity of the decoder. This paper exploits the scalability on the hardware and the algorithmic level to synergize the performance and to reduce the computational complexity. First, we propose a modular deblocking filter architecture which can be scaled to adapt to the required computing capability for various bit-rates, resolutions, and frame rate of video sequences. The scalable architecture is based on FPGA using dynamic partial reconfiguration. This desirable feature of FPGAs makes it possible for different hardware configurations to be implemented during run-time. The proposed design can be scaled to filter up to four different edges simultaneously, resulting in significant reduction of total processing time. Secondly, our experiments show that significant reduction in computational complexity can be achieved by the increased presence of skipped macroblocks at lower bit-rates, thus, avoiding redundant filtering operations. The implemented architecture is evaluated using the Xilinx Virtex-4 ML410 FPGA board. The design operates at a maximum frequency of 103 MHz. The reconfiguration is done through Internal Configuration Access Port (ICAP) to achieve maximum performance needed by real time applications.

Study of modular transfer function-based optieal low-pass filter evaluation model and experiment

To evaluate the performance of optical low pass filter (OLPF) accurately, a new 2D digital imaging system model including an OLPF was created for the first time using the modular transfer function (MTF). An evaluation function was also established based on this model. To manifest the model and its evaluation, three typical OLPFs were studied. The results show that the Δ value of each filter undergoes a slow and slight decrease and then rapidly increases when the ideal optical system cutoff frequency is increased. The optieal system embedded with the 2-chip-4-point type OLPF created a better image than those with the other two OLPF's when the F number is greater than 44; whereas the OLPF of 3-chip-8-point type worked best when the F number is lower than 44 When the F number of the optical system is 28, namely, with a spatial cutoff frequency of 649 lp/mm, the filter of 3-chip-8-point type performs better than that of the 2-chip-4-point and 3-chip-4-point types. The Δ value of the first filter is 283% and 375%, lower than that of the other two filters, respeatively. That is, the filter performance is 283% and 375% higher. Finally, spatial frequency test shows that the moiré fringe and false colors can be seen in the last two pictures, while in the first, these effects are well eliminated. The theoretical calculations agree with the experimental results.

Bag filters for TPP

Cleaning of TPP flue gases with bag filters capable of pulsed regeneration is examined. A new filtering element with a three-dimensional filtering material formed from a needle-broached cloth in which the filtration area, as compared with a conventional smooth bag, is increased by more than two times, is proposed. The design of a new FRMI type of modular filter is also proposed. A standard series of FRMI filters with a filtration area ranging from 800 to 16,000 m2 is designed for an output more than 1 million m3/h of with respect to cleaned gas. The new bag filter permits dry collection of sulfur oxides from waste gases at TPP operating on high-sulfur coals. The design of the filter makes it possible to replace filter elements without taking the entire unit out of service.

Modular active noise air filter speaker and microphone assembly

An air induction system comprises an air induction body and air filter to provide filtered air to a vehicle engine. A microphone is disposed within the air filter. A control unit may receive signals from the microphone. The control unit may further control a speaker, which produces a noise canceling sound to thereby reduce engine noise associated with the air induction system.

Designing bandpass filters in 8 – 14 ?m range for Si and Ge substrates

Modular bandpass spectral filter for germanium and silicon substrates in 8 - 14 μm band applications have been proposed. The design approach, similar to antireflection coating design has been adopted to make the model simple with lesser number of layers. The full width half maximum (FWHM) value of the filter for the two substrates is varied by varying the refractive index of a single layer in the multilayer stack. The design is also analyzed for zero and 45 degree angles of incidence. The analysis has shown that the designed configuration exhibits identical behavior for these two substrates. The proposed configuration could be used for different optical and optoelectronic applications.

Parallel Recursive Computation of the Inverse Legendre Moment Transforms for Signal and Image Reconstruction

The inverse Legendre moment transform plays an important role in the field of image analysis applications. A recursive algorithm based on Clenshaw's recurrence formula is derived for the fast computation of the inverse Legendre moment transform for signal and image reconstruction purposes. The reconstruction can be implemented effectively using recursive equations. The presented algorithm is particularly suitable for parallel very large-scale integrated circuit (VLSIC) implementation due to its regular, modular, and simple filter structure.

Novel coupling schemes for microwave resonator filters

This paper introduces novel coupling schemes for microwave resonator filters. It is shown that higher order filter characteristics can be obtained from lower order sections, which are connected in parallel between the source and load, by proper superposition of the individual lower order responses. This property can be used in modular filter design by focusing on separate sections of the filter one at a time. In addition, some of these coupling schemes exhibit zero-shifting properties, whereby transmission zeros can be shifted from one side of the passband to the other by simply changing the resonant frequencies of the resonators while keeping all the coupling coefficients unchanged. Several novel filter designs of different kinds (microstrip, planar waveguide cavity, and dual-mode types) are introduced to prove the new method and to give an idea of the extended design possibilities. Good agreement between measured, computed, and synthesized results is demonstrated.

Multi converter approach to active power filtering using current source converters

Active power filtering is performed by detecting the line current and voltage signals, generating a current equal-but-opposite to the distortion current using a power converter and injecting the compensating current into the power line. In such applications, it is desirable to combine high power and high switching frequency while minimizing the losses. This asks for special converter topologies and control techniques. In this paper, a multi-converter active power-line filter, based on current-source converter (CSC) modules, is proposed. The power rating and switching frequency of each CSC module is equal to those required for the filtering job divided by the number of modules. The control system utilizes two linear adaptive neurons (ADALINE's) to process the signals obtained from the line. The first ADALINE (the current ADALINE) extracts the harmonic components of the distorted line current signal and the second ADALINE (the voltage ADALINE) estimates the fundamental component of the line voltage signal. The outputs of both ADALINE's are used to construct the modulating signals of the filter modules. The proposed modular active filter offers the following advantage: (1) high efficiency due to low conduction and switching losses; (2) high reliability; and (3) high serviceability. The proposed active power-line filter treats the AC system on a per-phase basis, has fast response and adapts to the load variations. Theoretical expectations are verified by digital simulation using EMTDC simulation package.

00/00830 Reactance one-port compensator and modular active filter for voltage and current harmonic reduction in nonlinear distribution systems: A comparative study

00/00830 Reactance one-port compensator and modular active filter for voltage and current harmonic reduction in nonlinear distribution systems: A comparative study

Reactance one-port compensator and modular active filter for voltage and current harmonic reduction in nonlinear distribution systems: A comparative study

Abstract Harmonic distortion levels in electrical distribution systems have escalated recently due to the increasing presence of nonlinear and electronically-switched loads. This paper presents a comparative study between two different approaches to cancel harmonic distortion in nonlinear distribution systems. A modular active filter based on linear adaptive neuron (ADALINE) extraction technique and a reactance one-port compensator, that is in current resonance with the load, were designed and tested utilizing a secondary distribution feeder. Both attenuation and diversity effects have been taken into consideration during the design procedure. Filter sensitivity to elements’ values deviation and operating point variation were examined. The harmonic analysis was carried out in the time-domain using the EMTDC package.

A Modular Analog NLMS Structure for Adaptive Filtering

This paper proposes a modular Analog Adaptive filter (AAF) algorithm, in which the coefficient adaptation is carried out by using a time varying step size analog normalized LMS (NLMS) algorithm, which is implemented as an external analog structure. The proposed time varying step size is estimated by using the first element of the crosscorrelation vector between the output error and reference signal, and the first element of the crosscorrelation vector between the output error and the adaptive filter output signal, respectively. Proposed algorithm reduces distortion when additive noise power increases or DC offsets are present, without significatively decreasing the convergence rate nor increasing the complexity of the conventional NLMS algorithms. Simulation results show that proposed algorithm improves the performance of AAF when DC offsets are present. The proposed VLSI structure for the time varying step size normalized NLMS algorithm has, potentially, a very small size and faster convergence rates than its digital counterparts. It is suitable for general purpose applications or oriented filtering solution such as echo cancellation and equalization in cellular telephony in which high performance, low power consumption, fast convergence rates and small size adaptive digital filters (ADF) are required. The convergence performance of analog adaptive filters using integrators like first order low pass filter is analyzed.

Combining constructed wetlands and aquatic and soil filters for reclamation and reuse of water

Reclamation and reuse of water and nutrients at their source provide the opportunity to use simple, less costly technologies and lessens potentials for catastrophic effects due to centralized treatment system failures. The combination of multiple treatment environments within constructed wetlands can provide water quality suitable for reuse. A current project in rural Chatham County, NC, uses simple, aesthetically pleasing treatment components constructed both outdoors and indoors to reclaim domestic sewage for toilet flushing, landscape irrigation and aesthetic water features. A courtyard containing constructed wetlands and a solarium with modular soil filter components and aquatic chambers are designed to treat sewage from within a small business facility and to provide recreational space for its 60 employees. The combination of vertical flow and horizontal flow constructed wetlands with fill and draw controls provides the necessary environments for nitrification–denitrification, removal of organic materials and phosphorus adsorption reactions. The system is designed to treat and reuse 4500 l day −1 (1200 gal day −1) of domestic sewage from the business. Some of the plants used are selectively bred or genetically engineered to maximize their water reclamation potential. Utilization of simple treatment and reuse technology has permitted the business owner to renovate an abandoned and deteriorating school building into a home for two thriving and internationally based businesses and to protect the water quality of a nearby reservoir.