In the FFT computation, the butterflies play a central role, since they allow calculation of complex terms. In this calculation, involving multiplications of input data with appropriate coefficients, the optimization ...
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In the FFT computation, the butterflies play a central role, since they allow calculation of complex terms. In this calculation, involving multiplications of input data with appropriate coefficients, the optimization of the butterfly can contribute for the reduction of power consumption of FFT architectures. In this paper different and dedicated structures for the 16 bit-width radix-2 and radix-4 DIT butterflies are implemented, where the main goal is to minimize the number of arithmetic operators in order to produce power-efficient structures. Firstly, we improve a radix-2 butterfly previously presented in literature, reducing one adder and one subtractor in the structure. After that, part of this optimized radix-2 butterfly is used to reduce the number of real multipliers in the radix-4 butterfly. The main results show that the optimization guarantees reduced power consumption for radix-2 butterfly, when compared with previous works from the literature. Moreover, the use of part of the optimized radix-2 into the radix-4 structure leads to the reduction of power consumption for this structure.
Digital filters are widely used in digital systems, which can make use of integer arithmetic to achieve higher performance. The use of integer operands can compromise the filter operation, due to the inherently error ...
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Digital filters are widely used in digital systems, which can make use of integer arithmetic to achieve higher performance. The use of integer operands can compromise the filter operation, due to the inherently error caused by truncation operations. Addressing this kind of problem, we propose an IIR filter for biomedical signals using the truncation error feedback (TEF), in which a feedback signal is obtained from the division remainder of the truncation operation. Two dedicated fully-sequential and parallel architectures were implemented and simulated using VHDL language, and synthesized in Cadence environment using the 45 nm Nangate Open Cell Library. A simulated ECG signal was used as input to verify the functionality of an IIR high pass filter with TEF. The results of our analysis indicate that the use of TEF can be an important approach in digital systems, where integer arithmetic for computation is adequate for performance requirements. Using this feedback signal, the design specifications of the filter remained significantly the same compared to the filter specification, independently of the cut-off and sample frequency ratio.
This paper presents an power-efficient imprecise radix-4 multiplier applied to filtering Hi-Res (High Resolution) audio. The proposed multiplier was based on an imprecise 2×2 (m=2) multiplication block in order t...
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ISBN:
(纸本)9781509061143
This paper presents an power-efficient imprecise radix-4 multiplier applied to filtering Hi-Res (High Resolution) audio. The proposed multiplier was based on an imprecise 2×2 (m=2) multiplication block in order to implement optimized 2's complement radix-2 m array multipliers. The imprecise 2×2 multiplication block was previously proposed in literature, and presents as main characteristic a tunable error that enables the building of an imprecise radix-4 multiplier with a reduced number of logic gates. Since in the radix-2 m multiplier architecture the operands are split into groups of m bits, then, the m=2 imprecise multiplier is used as a basic component in its structure. Our work deals with different levels of approximation in the radix-2 m multiplier. We present four different approximate radix-4 multipliers architectures to be used in sequential FIR filters implemented in hardware. The filters are described in VHDL and synthesized for ASIC in Cadence RTL Compiler tool using Nangate 45nm standard cells. The power reports are evaluated using real input vectors from Hi-Res audio sequences in order to obtain valid power dissipation results. The imprecise FIR filters present area and power reductions of up to 5.7% and 12.5% when compared to the precise designs without compromising the Signal to Noise Ratio (SNR) of recorded 24-bit@192kHz Hi-Res audio signals.
This paper proposes a novel approximate computing algorithm for the Sum of Absolute Transformed Differences (SATD) to meet energy efficiency in CMOS accelerator circuits. It is based on the pruning of least significan...
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This paper proposes a novel approximate computing algorithm for the Sum of Absolute Transformed Differences (SATD) to meet energy efficiency in CMOS accelerator circuits. It is based on the pruning of least significant coefficients in the 2-D Hadamard Transform (HT) which is the most compute intensive kernel in the SATD. The SATD is a metric for block matching that is used in video coding standards like the new High Efficiency Video Coding (HEVC). This metric is used to provide better results in mode decision when compared to the Sum of Absolute Differences (SAD) at the expense of larger amount of arithmetic operations as well as higher energy consumption. We present 6 different approximate SATD 4×4 architectures that were synthesized for a 45 nm PDK. Results for the approximate architecture with 10 discarded HT coefficients show energy per operation reduction of 70.7% and BD-PSNR reduction of just -0.008 dB, for a 1080p video sequence.
KAGRA is a newly built gravitational wave observatory, a laser interferometer with a 3 km arm length, located in Kamioka, Gifu prefecture, Japan. In this article, we describe the KAGRA data management system, i.e...
KAGRA is a newly built gravitational wave observatory, a laser interferometer with a 3 km arm length, located in Kamioka, Gifu prefecture, Japan. In this article, we describe the KAGRA data management system, i.e., recording of data, transfer from the KAGRA experiment site to computing resources, as well as data distribution to tier sites, including international sites in Taiwan and Korea. The amount of KAGRA data exceeded 1.0 PiB and increased by about 1.5 TB per day during operation in 2020. Our system has succeeded in data management, and has achieved performance that can withstand observations after 2023, that is, a transfer rate of 20 MB s-1or more and file storage of sufficient capacity for petabyte class. We also discuss the sharing of data between the global gravitational-wave detector network with other experiments, namely LIGO and Virgo. The latency, which consists of calculation of calibrated strain data and transfer time within the global network, is very important from the view of multi-messenger astronomy using gravitational waves. Real-time calbrated data delivered from the KAGRA detector site and other detectors to our computing system arrive with about 4–15 seconds of latency. These latencies are sufficiently short compared to the time taken for gravitational wave event search computations. We also established a high-latency exchange of offline calibrated data that was aggregated with a better accuracy compared with real-time data.
This paper proposes the exploration of approximate adders for the implementation of power-efficient Gaussian and Gradient filters for Image Processing. The Gaussian filter is a convolution operator which is used to bl...
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This paper proposes the exploration of approximate adders for the implementation of power-efficient Gaussian and Gradient filters for Image Processing. The Gaussian filter is a convolution operator which is used to blur images and to remove noise. On the other hand, the Gradient of an image measures how it is changing. Both blocks can be designed in hardware using only shifts and additions. In this work we exploit a set of approximate adders in order to implement energy-efficient filters. The tree of adders of Gaussian and Gradient filters are implemented using one RCA-based approximate adder, as well as an Error-Tolerant Adder ETAI. The approximate architectures are compared to the best precise implementation of the filters. As the Gaussian and Gradient blocks are part of the Canny edge detector algorithm, we have implemented the adder trees of the filters aiming this application. Our main results show that for an efficient power realization of this algorithm, the best strategy consists in the implementation of the Gaussian filter with ETA I adder, and the Gradient filter with the RCA-based adder.
We report on the population properties of compact binary mergers inferred from gravitational-wave observations of these systems during the first three LIGO-Virgo observing runs. The Gravitational-Wave Transient Catalo...
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We report on the population properties of compact binary mergers inferred from gravitational-wave observations of these systems during the first three LIGO-Virgo observing runs. The Gravitational-Wave Transient Catalog 3 (GWTC-3) contains signals consistent with three classes of binary mergers: binary black hole, binary neutron star, and neutron star–black hole mergers. We infer the binary neutron star merger rate to be between 10 and 1700 Gpc−3 yr−1 and the neutron star–black hole merger rate to be between 7.8 and 140 Gpc−3 yr−1, assuming a constant rate density in the comoving frame and taking the union of 90% credible intervals for methods used in this work. We infer the binary black hole merger rate, allowing for evolution with redshift, to be between 17.9 and 44 Gpc−3 yr−1 at a fiducial redshift (z=0.2). The rate of binary black hole mergers is observed to increase with redshift at a rate proportional to (1+z)κ with κ=2.9−1.8+1.7 for z≲1. Using both binary neutron star and neutron star–black hole binaries, we obtain a broad, relatively flat neutron star mass distribution extending from 1.2−0.2+0.1 to 2.0−0.3+0.3M⊙. We confidently determine that the merger rate as a function of mass sharply declines after the expected maximum neutron star mass, but cannot yet confirm or rule out the existence of a lower mass gap between neutron stars and black holes. We also find the binary black hole mass distribution has localized over- and underdensities relative to a power-law distribution, with peaks emerging at chirp masses of 8.3−0.5+0.3 and 27.9−1.8+1.9M⊙. While we continue to find that the mass distribution of a binary’s more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above approximately 60M⊙, which would indicate the presence of a upper mass gap. Observed black hole spins are small, with half of spin magnitudes below χi≈0.25. While the majority of spins are preferentially aligned wi
This paper deals with the optimization of grounding grids geometry. The goal is to reduce the amount of material to deploy a grounding grid, while keeping the system security. The touch voltages, step voltages, GPR an...
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ISBN:
(纸本)9781509023219
This paper deals with the optimization of grounding grids geometry. The goal is to reduce the amount of material to deploy a grounding grid, while keeping the system security. The touch voltages, step voltages, GPR and ground resistance are parameters of grounding grids and are related to safety aspect. Also discussed is a genetic algorithm used for optimizing ground grids, which can assume any form in a limited space of the project. The simulation is based in images method. The results are presented and discussed.
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