John McAllister

Heavy metal concentrations in surface sediments in a nearshore environment, Jurujuba Sound, Southeast Brazil

Sixty-four surface sediment samples and seven cored samples were collected from the partially closed bay of Jurujuba Sound, an inlet of Guanabara Bay in Southeast Brazil. Analysis of metals, including Pb, Zn, Ni, Cu and Cr, shows levels consistent with those typically found in urbanised and industrialised estuarine environments. Metal enrichment is concentrated around the inshore margin of the Sound and is significantly in excess of background, geological concentrations observed in basal muds from the seven cores. In the absence of industrialisation within the steep, but limited catchment that feeds into the Sound, the metal enrichment, particularly of Pb, Zn and Cu, is ascribed to the uncontrolled discharge of untreated sewage waste and urban surface runoff. This has increased markedly since the beginning of rapid urbanisation following the linking of the area by bridge to Rio de Janeiro in 1974.

FPGA-based Implementation of Signal Processing Systems

Field programmable gate arrays (FPGAs) are an increasingly popular technology for implementing digital signal processing (DSP) systems. By allowing designers to create circuit architectures developed for the specific applications, high levels of performance can be achieved for many DSP applications providing considerable improvements over conventional microprocessor and dedicated DSP processor solutions. The book addresses the key issue in this process specifically, the methods and tools needed for the design, optimization and implementation of DSP systems in programmable FPGA hardware. It presents a review of the leading-edge techniques in this field, analyzing advanced DSP-based design flows for both signal flow graph- (SFG-) based and dataflow-based implementation, system on chip (SoC) aspects, and future trends and challenges for FPGAs. The automation of the techniques for component architectural synthesis, computational models, and the reduction of energy consumption to help improve FPGA performance, are given in detail. Written from a system level design perspective and with a DSP focus, the authors present many practical application examples of complex DSP implementation, involving: high-performance computing e.g. matrix operations such as matrix multiplication; high-speed filtering including finite impulse response (FIR) filters and wave digital filters (WDFs); adaptive filtering e.g. recursive least squares (RLS) filtering; transforms such as the fast Fourier transform (FFT). FPGA-based Implementation of Signal Processing Systems is an important reference for practising engineers and researchers working on the design and development of DSP systems for radio, telecommunication, information, audio-visual and security applications. Senior level electrical and computer engineering graduates taking courses in signal processing or digital signal processing shall also find this volume of interest.

Reconfigurable Computing: Architectures, Tools and Applications

Clustering of a large number of data points is a computational demanding task that often needs the be accelerated in order to be useful in practice. The focus of this work is on the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, which is one of the state-of-the-art clustering algorithms, targeting its acceleration using an FPGA device. The paper presents a novel, optimised and scalable architecture that takes advantage of the internal memory structure of modern FPGAs in order to deliver a high performance clustering system. Results show that the developed system can obtain average speed-ups of 32x in real-world tests and 202x in synthetic tests when compared to state-of-the-art software counterparts.

Benthic foraminifera distribution in high polluted sediments from Niterói Harbor (Guanabara Bay), Rio de Janeiro, Brazil

Dockyards and harbors are recognized as being important locations where sediment-associated pollutants can accumulate, which constitutes an environmental risk to aquatic life due to potential uptake and accumulation of heavy metals in the biota. The aim of this paper is to assess the concentrations and the effects of some heavy metals in the benthic foraminifera assemblage in Niterói Harbor. Low concentrations in the benthic foraminifera as well as the dominance of indicative species such as Ammonia tepida, Buliminella elegantissima and Bolivina lowmani can be associated with an environment under stress. In addition, the occurrence of test abnormalities among foraminifera may represent a useful biomarker for evaluating long-term environmental impacts in a coastal region.

QR Decomposition-Based Matrix Inversion for High Performance Embedded MIMO Receivers

Real-time matrix inversion is a key enabling technology in multiple-input multiple-output (MIMO) communications systems, such as 802.11n. To date, however, no matrix inversion implementation has been devised which supports real-time operation for these standards. In this paper, we overcome this barrier by presenting a novel matrix inversion algorithm which is ideally suited to high performance floating-point implementation. We show how the resulting architecture offers fundamentally higher performance than currently published matrix inversion approaches and we use it to create the first reported architecture capable of supporting real-time 802.11n operation. Specifically, we present a matrix inversion approach based on modified squared Givens rotations (MSGR). This is a new QR decomposition algorithm which overcomes critical limitations in other QR algorithms that prohibits their application to MIMO systems. In addition, we present a novel modification that further reduces the complexity of MSGR by almost 20%. This enables real-time implementation with negligible reduction in the accuracy of the inversion operation, or the BER of a MIMO receiver based on this.

Sedimentological evidence of human impact on a nearshore environment: Jurujuba Sound, Rio de Janeiro State, Brazil

Abstract The sedimentological and geochemical characteristics of nearshore deposits are examined using cores collected from a semi-enclosed marine embayment. Recent urbanization within the contributing catchment has stimulated the rapid accumulation of heterogeneous sediment rich in the kaolinite/illite clays that are characteristic of regional topsoils. Sediments also contain a high concentration of lead derived from street dust and elevated levels of copper and zinc associated with the uncontrolled discharge of untreated sewage wastes from disposal sources around the bay. Radiocarbon dating of shell fragments at depth in the cores places an earlier phase of accelerated but uncontaminated deposition in the 17th century, possibly as a result of early land clearance by European colonists.

Real-Valued Fixed-Complexity Sphere Decoder for High Dimensional QAM-MIMO Systems

The development of high performance, low computational complexity detection algorithms is a key challenge for real-time multiple-input multiple-output (MIMO) communication system design. The fixed-complexity sphere decoder (FSD) algorithm is one of the most promising approaches, enabling quasi-ML decoding accuracy and high performance implementation due to its deterministic, highly parallel structure. However, it suffers from exponential growth in computational complexity as the number of MIMO transmit antennas increases, critically limiting its scalability to larger MIMO system topologies. In this correspondence, we present a solution to this problem by applying a novel cutting protocol to the decoding tree of a real-valued FSD algorithm. The new real-valued fixed-complexity sphere decoder (RFSD) algorithm derived achieves similar quasi-ML decoding performance as FSD, but with an average 70% reduction in computational complexity, as we demonstrate from both theoretical and implementation perspectives for quadrature amplitude modulation (QAM)-MIMO systems.

The contribution of heavy metal pollution derived from highway runoff to Guanabara Bay sediments: Rio de Janeiro / Brazil

In this study, geochemical and particle size analyses of thirty-four street sediment samples collected from an urban environment around Guanabara Bay, shows highway run-off to be a potential source of heavy metals for the pollution of near-shore sedimentary deposits. Concentrations of Fe, Mn, Zn, Cu, Pb, Cr and Ni were found to be higher in these sediments when compared to concentrations found in samples from the natural environment, where an Enrichment Factor (EF) index was used to distinguish between natural and anthropogenic sources. Particle size analysis shows these sediments to be predominantly composed of sand and no distribution pattern was observed between the sand, silt and clay fractions. High levels of organic matter and heavy metals would indicate that these street run-off materials are a potential source of pollution for the near-shore sediments of Guanabara Bay.

Targeting FPGA DSP Slices for a Large Integer Multiplier for Integer Based FHE

Homomorphic encryption offers potential for secure cloud computing. However due to the complexity of homomorphic encryption schemes, performance of implemented schemes to date have been unpractical. This work investigates the use of hardware, specifically Field Programmable Gate Array (FPGA) technology, for implementing the building blocks involved in somewhat and fully homomorphic encryption schemes in order to assess the practicality of such schemes. We concentrate on the selection of a suitable multiplication algorithm and hardware architecture for large integer multiplication, one of the main bottlenecks in many homomorphic encryption schemes. We focus on the encryption step of an integer-based fully homomorphic encryption (FHE) scheme. We target the DSP48E1 slices available on Xilinx Virtex 7 FPGAs to ascertain whether the large integer multiplier within the encryption step of a FHE scheme could fit on a single FPGA device. We find that, for toy size parameters for the FHE encryption step, the large integer multiplier fits comfortably within the DSP48E1 slices, greatly improving the practicality of the encryption step compared to a software implementation. As multiplication is an important operation in other FHE schemes, a hardware implementation using this multiplier could also be used to improve performance of these schemes.

FPGA based soft-core SIMD processing: A MIMO-OFDM Fixed-Complexity Sphere Decoder case study

To enable reliable data transfer in next generation Multiple-Input Multiple-Output (MIMO) communication systems, terminals must be able to react to fluctuating channel conditions by having flexible modulation schemes and antenna configurations. This creates a challenging real-time implementation problem: to provide the high performance required of cutting edge MIMO standards, such as 802.11n, with the flexibility for this behavioural variability. FPGA softcore processors offer a solution to this problem, and in this paper we show how heterogeneous SISD/SIMD/MIMD architectures can enable programmable multicore architectures on FPGA with similar performance and cost as traditional dedicated circuit-based architectures. When applied to a 4×4 16-QAM Fixed-Complexity Sphere Decoder (FSD) detector we present the first soft-processor based solution for real-time 802.11n MIMO.