Modular Filter Research Articles

Multilevel split-path adaptive filtering and its unification with discrete Walsh transform adaptation

It has been shown that the convergence speed of an adaptive transversal filter can be made faster if the filter is split into a pair of symmetric/antisymmetric linear phase subfilters. In this brief, a generalized multilevel splitting approach is proposed which enables the realization of a modular split-path adaptive filter. It is demonstrated that an LMS FIR filter of length 2L, where L is an integer, can be decomposed into a set of parallel single-parameter subfilters by a novel L-step splitting procedure. The convergence behavior of the new filter configuration is improved noticeably and is confirmed experimentally. A unified perspective of the multilevel split-path adaptive filtering method with the discrete Walsh transform adaptation is also established.

An intelligent filter control system using fuzzy logic for APS insertion device beamlines

A modular filter has been designed for the white-beam undulator/wiggler beamlines at the Advanced Photon Source. For a typical hard x-ray application, the filter assembly consists of four filter banks, and each bank has five beam apertures. Therefore a maximum of 625 filter combinations is mechanically possible. To prevent any mistaken setup, which could either damage the filter itself or downstream optical components, a programmable logic controller (PLC) based protection system has been designed. Fuzzy logic was used in this system to limit the memory size and improve the system performance. Ten different storage-ring beam currents and ten insertion-device gap setups have been chosen to cover a large dynamic operation range. Aspects of the system fuzzy logic design as well as an example of the calculated results for the control database are presented in this paper.

Modular filter design for the white-beam undulator/wiggler beamlines at the Advanced Photon Source

A new filter has been designed at Argonne National Laboratory that is intended for the use in undulator/wiggler beamlines at the Advanced Photon Source. The water-cooled frame allows up to four individual filter foil banks simultaneously in the beam path. Additionally, the bottom of each frame holds two thin (20 μm) uncooled carbon filters in tandem for low-energy filtering. Therefore a maximum of 625 filter selection combinations is theoretically possible. The design is compact and modular, with great flexibility for the users. To prevent accidental movement of the filter, effort has been taken to provide a mechanically locked, fail-safe actuator system. Programming aspects are under development as part of the general personnel and equipment protection system to provide an intelligent control system. Aspects of the design and operational principles of the filter are presented in this paper.

Design and maintenance of a closed artificial seawater system for long-term holding of bivalve shellfish

To study the potential for transmission of Perkinsus karlssoni, an apicomplexan parasite, among bivalve hosts, a long-term laboratory-scale, closed, artificial seawater system for shellfish was designed. Species of shellfish utilised were as follows: bay scallops, Argopecten irradians; blue mussels, Mytilus edulis; eastern oysters, Crassostrea virginica; European oysters, Ostrea edulis; sea scallops, Placopecten megallanicus; softshell clams, Mya arenaria; and quahaugs, Mercenaria mercenaria. All shellfish used were juveniles with shell heights of 10–25 mm. The design was duplicated for control and experimental systems with a combined population of 1600 individual shellfish. The maximum biomass in each system was estimated at < 1 kg/m 3. Each system included six, 400 litre rectangular fibreglass tanks, a modular pump and filter unit (particle and activated carbon filters and ultra-violet sterilisers), a biological filter and a refrigeration unit. The total volume of water for each system was 2300 litres of artificial seawater (Instant Ocean ®). The mean water temperature of 22°C was achieved by thermostat-controlled room temperature. Salinity was maintained between 27 and 31‰ by addition of either freshwater or artificial seawater. Shellfish were fed daily a mixed diet of carboy-cultured algae and spray-dried algae. Mean values for water quality parameters in both systems were as follows: NH 3 < 0·004 mg/litre; NO 2 − < 0·01 mg/litre; NO 3 − < 19·16 mg/litre; and pH 8·0–8·4. The system design was adequate in maintaining healthy bivalves for a period of 22 months, with the exception of the sea scallops which succumbed to warm water. Mean monthly shellfish survival rates were 79·9–100% in the control and 74·8–98·9% in the experimental system. A method of controlling water temperature other than via room temperature should reduce slight seasonal temperature fluctuations.

Applications of 3-D LCR networks in the design of 3-D recursive filters for processing image sequences

Applications of three-dimensional (3D) LCR prototype networks in the design of 3D recursive filters are reviewed and several types of new and useful 3D LCR prototype filters are proposed and classified. These 3D LCR prototype filters can be used to design 3D recursive filters for the processing of image sequences involving 3D spatio-temporal-domain linear-trajectory (LT) and planar-wave (PW) component signals. Among the new proposed filters, a 3D planar-rejection (PR) filter can be used to reject an undesired spatially-varying or spatially-static background LT component signal; a 3D planar-pass/planar-rejection (PP-PR) filter can be tuned to enhance a desired 3D LT component signal and, at the same time, reject an undesired 3D LT component signal. A technique for implementing the 3D filter transfer functions is proposed that employs 3D differential or 3D integral operators, leading to highly-parallel and modular 3D recursive filter structures that are efficient in computation. A simple design procedure is described and examples of image sequence processing are given.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A simple method for cable compensation with fast pulse transmission applications

Abstract A simple method for compensating signal cable effects on fast pulse transmission is described. The effects which are compensated here are mainly the long tail, that appears when fast signals are transmitted through cables, and the deterioration of the rise time. The method described is rather general and suitable for many applications, including circuit design and off-line analysis. It characterizes cables by a summation of exponentials, which has proved to be an accurate and relatively easy to implement representation. The compensation network is then implemented in the frequency domain by means of pole-zero cancellation. The computer simulation results are presented and a modular active filter topology and design procedure are discussed. Experimental results using commercial cables are also included. The method has been used for acquiring and processing signals from the Spaghetti calorimeter which is currently being developed at CERN.

ARMA parameter estimation using a novel recursive estimation algorithm with selective updating

The authors investigate an extension of a recursive estimation algorithm (the so-called optimal bounding ellipsoid or OBE algorithm) which features a discerning update strategy. In particular, an extension of the algorithm to ARMA (autoregressive moving-average) parameter estimation is presented along with a convergence analysis. The extension is similar to the extended least-squares (ELS) algorithm. However, the convergence analysis is complicated due to the discerning update strategy, which incorporates an information-dependent updating factor. The virtues of such an update strategy are more efficient use of the input data in terms of information processing and a modular adaptive filter structure which would facilitate the development of a parallel-pipelined signal processing architecture. It is shown that if the input noise is bounded and the moving-average parameters satisfy a certain magnitude bound, then the a posteriori prediction errors are uniformly bounded. With an additional persistence-of-excitation condition, the parameter estimates are shown to converge to a neighborhood of the true parameters, and the a priori prediction errors are shown to be asymptotically bounded. Simulation results show that the parameter estimation error for the EOBE algorithm is comparable to that for the ELS algorithm. >

Design and function of closed seawater systems for culturing loliginid squids

The life cycle of loliginid squids has been completed in recirculating seawater systems. Two systems were required: a 2 m diameter circular culture tank (CT) with adjoining 2 m circular filter tank (3000 liters total volume of natural seawater) for culture of hatchlings, 1–60 days old; and a 6 × 2·6 × 1 m raceway culture tank (RW) with a smaller adjoining rectangular filter tank (14 850 liters total volume of artificial seawater) for the grow-out of adults. Both systems were equipped with temperature control apparatus, modular filter units (particle filters and activated carbon), foam fractionators, biological filters (crushed oyster shell) and UV sterilizers. The systems carried low bioloads, < 1·0 g/m 3 and as high as 0·8 kg/m 3, respectively. Water quality was excellent: NH 4N was below 0·01 mg/liter in the CT and 0·10 mg/liter in the RW: NO 2N was below 0·01 mg/liter in the CT and 0·03 mg/liter in the RW; NO 3N was below 12 mg/liter in the CT and below 50 mg/liter in the RW; and pH was above 8·0 in both systems. The design of the systems proved to be behaviorally and physiologically suitable for squids and two species grew to adult size and produced viable young. These systems are compared to other squid maintenance and rearing systems and marine recirculating seawater systems.

A sliced first-quadrant second-order two-dimensional digital filter chip set for modular filter implementation

Modular Miter structures for two-dimensional (2-D) filters were investigated and a filter function suitable for modular implementation of 2-D digital filters determined. Given this transfer function, a two-chip set was implemented in S micron NMOS technology. This chip set performs an all-pole or all-zero filtering operation in 4-bit slices (i.e. the wordlength is indefinitely expandable in an expansion chain) on a 512 × 512 pixel array using two's complement arithmetic. The chip set may be used as a building block for implementing general first-quadrant 2-D digital filters.

Parallel modular FIR digital filter

A parallel modular FIR digital filter structure is described which can achieve arbitrarily high sampling rates. Unlike pipeline and other published structures, the filter throughput need not be limited by the slowest arithmetic component in the system. High-speed performance is obtained by synchronous operation of a number of cooperating processors. This correspondence outlines the structure and gives cost/performance equations relating filter throughput and delay to component speed and the number of processors.

A Modular Nitrification Filter Design Based on a Study of the Kinetics of Nitrification of Marine Bacteria

ABSTRACTThe scope and significance of the problem of maintaining the quality of the water in recirculating mariculture systems is discussed. A quantitative study of the kinetics of important nutrient cycles is proposed as a means of establishing minimum system volumes, optimization of design, and the requisite environmental controls. Significant results in a study of inorganic nutrient nitrogen cycling and toxicity in recirculating systems is reported. A modular filter design suggested by a study of the kinetics of nitrification in marine systems demonstrates how a knowledge of kinetic and chemical factors can lead to more efficient water treatment hardware.