Constant Throughput Research Articles

Flexible FPGA 1D DCT hardware architecture for HEVC

In this work, we propose a flexible 1D DCT hardware design with a constant throughput of 32 pixels per cycle for all transform block (TB) size modes. The design supports all TB sizes defined in the HEVC standard. Flexibility is achieved by multiplexing only the outputs, which results in lower data path delays compared to other proposed designs. Also, the additional partial butterfly units are transferred to the output of transformation cores. The transformation operation is done in a single stage to minimize the latency of the design and reduce hardware usage. The highly parallel input reduces the need for a very high operational frequency, which is suitable for low-power FPGA designs. Four different reusable transformation cores are used that are designed using parallel Multiple Constant Multiplication (MCM) units to further reduce the calculation time. The design was implemented on the Virtex UltraScale + device. The implementation has hardware usage of 21,818 LUTs, and it can reach the maximal throughput of 4.90 Gsps at the working frequency of 153 MHz which is enough to support the video resolutions of up to 8192 × 4320@60fps. Comparison with the other works shows that DCT FPGA implementation without DSPs can reach the performance of the ASICs with trade-offs in power consumption.

The IAU recommended photometric system for ultraviolet astronomy

In the current era when access to space is becoming easier and at a lower cost thanks to the standardised cubesat technology, numerous missions are expected to be launched to observe, particularly, at ultraviolet wavelengths. Given the reduced dimensions of the telescope that a cubesat can carry, most of these missions will be focused on photometric surveys of a reduced sample of targets of interest, and therefore each mission will define their own photometric bands according to their scientific objectives and orbital constraints. However, in order to provide a coherent view of the ultraviolet sky, the data should be post-processed under a common framework. In 2017, the IAU working group on ultraviolet astronomy identified the need to define such a common framework for the upcoming ultraviolet missions, and coordinated the definition of a standard set of photometric bands that could serve for homogenizing the current and future data. This paper presents the procedure adopted by the working group for the definition of the standard photometric system, that was approved by the IAU during the General Assembly Business Sessions held in August, 2021. The photometric system consists of seven bands, denoted as UV1-UV7, all included in the range 115 - 400 nm. Some of these bands are based on existing filters, while others have been defined as theoretical bands with constant throughput. This system is to be regarded as a set of synthetic bands for post-processing the data of any mission, and an example of its application to the SPARCS cubesat is also included. The photometric bands are publicly available and can be downloaded from https://www.nuva.eu/uv-photometry/.

A Reconfigurable Multiple Transform Selection Architecture for VVC

Video coding plays an important role in the highly information-based world as videos contribute the largest part of network traffic. The latest video coding standard Versatile Video Coding (VVC) introduces a new transform scheme multiple transform selection (MTS), which brings considerable coding gains at the expense of high coding complexity. In this article, we propose a reconfigurable MTS architecture that supports all transform types in VVC with square and rectangular sizes ranging from 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 4 to 32 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 32. Firstly, we explore the features of three types of transform matrices and extract the features that are beneficial to designing a unified architecture. Then, we present an improved calculation scheme for general transforms, where the transform matrix is decomposed into two simpler matrices to increase the similarity and decrease the complexity of matrices involved in three types of transform operations. Thanks to the improved calculated scheme, a unified shift-adder unit (SAU) is designed and highly reused by different types. Moreover, we provide a twirling two-point splicing (T2S) scheme to improve reusability and deal with issues of data mismatch when conducting discrete cosine transform (DCT)-II of different sizes. As a consequence, an architecture with constant throughput of 32 pixels/cycle is implemented and specified in Verilog HDL. The synthesis results indicate that the application specific integrated circuit (ASIC)-based and field-programmable gate array (FPGA)-based hardware architectures achieve significant advantages both in area reduction and power consumption compared to existing methods in the literature.

Blockchain databases: Encrypted for efficient and secure NoSQL key-store

Databases have revealed many vulnerabilities in which hackers can penetrate and gain access to the data. Blockchains have been proven useful to protect against fraud and data miners, exemplified in cryptocurrencies. In this paper, we propose a blockchain database framework as a non-relational database structure that integrates the properties of blockchains and databases. The independent variables when testing this database were the Append, Delete, Query, and Update functions in the database framework. We predicted that the Append, Query, and Update functions would have a logarithmic runtime and linear throughput; while the Delete function would have a constant runtime and throughput. The database was tested with about 150,000 operations with the server and client locally running. We observed the runtime was slightly positively correlated while the Delete was not positively correlated with the number of operations in the Append, Query, and Update functions. The throughput of the Append, Query, and Update functions were significantly negatively correlated with the number of operations. The blockchain database framework displayed end-to-end encryption and feasibility with this experiment. One possible application of the database framework is in the financial industry, as there is a one-to-one correspondence with user and transaction.

Numerical study of influence of mould width on freestanding adjustable combination electromagnetic brake in continuous casting mould

A mathematical model was developed to describe the behavior of liquid steel flow and the steel/slag interface at a constant casting throughput in moulds of different widths. The impact of mould width (MW) on the liquid steel flow and the steel/slag interface was analyzed. Further it was examined whether a freestanding adjustable combination electromagnetic brake (FAC-EMBr) was conducive to controlling and improving the liquid steel flow. The results indicate that increasing MW decreased impact strength of the jet, upward backflow, and surface velocity––this was beneficial for reducing the meniscus height. Adjustment of the current intensity would enable the control of the behaviour of the liquid steel flow and meniscus, as well as reduce the dependence on matching the electromagnetic parameters and process parameters. This simplifies the operational process. As the MW increased to 1600 mm, an excessive input current of the vertical pole (IV = 250 A) significantly decreased the upward backflow velocity; this was not conducive to melting the mould powder.

FPGA based Speech Separation using IPD Features

The problem of speaker separation is an established field in science and goes back to the cocktail party problem defined in 1953. For decades, methods have been improved and developed, but the computational complexity is rarely considered just as the possibility to use hardware acceleration mechanisms. For this reason, this paper addresses the research question: how speaker separation can be realized on embedded systems by exploiting parallelization and intelligent hardware/software partitioning. For this purpose, a concept is described which uses an FPGA for parallelization to separate a speech signal from an intended direction providing a constant throughput rate. The implementation results show the independence of FPGA resources except BRAM size, proving the scalability of the concept, just as the real-time capabilities.

An Efficient Architecture and High-Throughput Implementation of CCSDS-123.0-B-2 Hybrid Entropy Coder Targeting Space-Grade SRAM FPGA Technology

Nowadays, hyperspectral imaging is recognized as cornerstone remote sensing technology. The explosive growth in image data volume and instrument data rates, compete with limited on-board storage resources and downlink bandwidth, making hyperspectral image data compression a mission critical on-board processing task. The Consultative Committee for Space Data Systems (CCSDS) extended the previous issue of the CCSDS-123.0 Recommended Standard for multi- and hyperspectral image compression to provide with Near-Lossless compression functionality. A key feature of the CCSDS-123.0-B-2 is the improved Hybrid Entropy Coder, which at low bit rates, provides substantially better compression performance than the Issue 1 entropy coders. In this paper, we introduce a high-throughput hardware implementation of the CCSDS-123.0-B-2 Hybrid Entropy Coder. The introduced architecture exploits the systolic design pattern to provide modularity and latency insensitivity in a deep and elastic pipeline achieving a constant throughput of 1 sample/cycle with a small FPGA resource footprint. This architecture is described in portable VHDL RTL and is implemented, validated and demonstrated on a commercially available Xilinx KCU105 development board hosting a Xilinx Kintex Ultrascale XCKU040 SRAM FPGA, and thus, is directly transferable to Xilinx Radiation Tolerant Kintex UltraScale XQRKU060 space-grade devices for space deployments. Moreover, state-of-the-art SpaceFibre (ECSS-E-ST-50-11C) serial link interface and test equipment were used in the validation platform to emulate an on-board deployment. The introduced CCSDS-123.0-B-2 Hybrid Entropy Encoder achieves a constant throughput performance of 305 MSamples/s. To the best of our knowledge, this is the first published fully-compliant architecture and high-throughput implementation of the CCSDS-123.0-B-2 Hybrid Entropy Coder, targeting space-grade FPGA technology.

Low-complexity scheduling algorithms with constant queue length and throughput guarantees

Distributed scheduling algorithms based on carrier sense multiple access (CSMA) are optimal in terms of the throughput and the steady-state queue lengths. However, they take a prohibitively long time to reach the steady-state, often exponential in the network size. Therefore for large networks that operate over a finite time horizon, apart from the guarantees on the steady-state queue lengths, performance guarantees on the short-term (i.e., transient) queuing behaviour are also required. To that end, we propose distributed scheduling algorithms that are guaranteed to have O(1) expected queue lengths not just in the steady-state but at every time instant, where O(⋅) is with respect to the network size. Further, our algorithms have O(1) complexity and support a constant fraction of the maximum throughput for typical wireless topologies. The central idea of our algorithms is to resolve collisions among pairs of conflicting nodes by assigning a master–follower hierarchy. The master–follower hierarchy can either be chosen randomly or based on the topology of the conflict graph, leading to different performance guarantees.In addition to these hierarchical collision resolution algorithms, which are primarily designed for the conflict graph-based interference model, we also propose an Aloha-based algorithm for the K-neighbour collision tolerance interference model, which is a generalization of the conflict graph model. We show that the proposed Aloha-based algorithm supports a constant fraction of the maximum throughput for typical wireless topologies.

Lightweight Hardware Transform Design for the Versatile Video Coding 4K ASIC Decoders

Versatile Video Coding (VVC) is the next generation video coding standard finalized in July 2020. VVC introduces new coding tools enhancing the coding efficiency compared to its predecessor High Efficiency Video Coding (HEVC). These new tools have a significant impact on the VVC software decoder complexity estimated to 2 times HEVC decoder complexity. In particular, the transform module includes in VVC separable and non-separable transforms named Multiple Transform Selection (MTS) and Low Frequency Non-Separable Transform (LFNST) tools, respectively. In this paper, we present an area-efficient hardware architecture of the inverse transform module for a VVC decoder. The proposed design uses a total of 64 regular multipliers in a pipelined architecture targeting Application-Specific Integrated Circuit (ASIC) platforms. It consists in a multi-standard architecture that supports the transform modules of recent MPEG standards including Advanced Video Coding (AVC), HEVC and VVC. The architecture leverages all primary and secondary transforms’ optimisations including butterfly decomposition, coefficients zeroing and the inherent linear relationship between the transforms. The synthesized results show that the proposed method sustains a constant throughput of 1 sample per cycle and a constant latency for all block sizes. The proposed hardware inverse transform module operates at 600 MHz frequency enabling to decode in real-time 4K video at 30 frames per second in 4:2:2 chroma sub-sampling format. The proposed module has been integrated in an ASIC UHD decoder targeting energy-aware decoding of VVC videos on consumer devices.

Screening of alkali‐assisted storage conditions to define the operational window of deacetylation within storage systems in the bioenergy supply chain

AbstractOvercoming biomass heterogeneity and associated recalcitrance to thermal, chemical, and enzymatic depolymerization is a necessary but challenging aspect of valorizing lignocellulosic biomass to fuels and chemicals. This study explores how this recalcitrance can be reduced during the supply chain unit operation of storage, which is required for seasonally harvested agricultural residues to maintain constant throughput at a biorefinery. In this work, partial alkali pretreatment was performed just prior to corn stover entering storage, which had the benefit of providing a high pH environment entering storage such that soluble sugars were preserved and saponified acetyl groups in hemicellulose. This work investigated a range of viable conditions where saponification and preservation occur simultaneously by varying the moisture content (40% and 60%) and concentrations of sodium hydroxide (low and high) during aerobic and anaerobic storage. Anaerobic conditions preserved overall dry matter below 5% in the three scenarios evaluated, and the highest alkali loading solubilized up to 15% lignin, 18% xylan, and 50% of acetate, meanwhile doubling the extractable components. Scanning electron microscopy images highlighted potential physical impacts including cell‐wall disruption near vascular bundles, pitting within parenchyma cells, and cell‐wall distortion. Techno‐economic assessment indicated that this storage approach and associated logistics system is economically competitive with a conventional approach using low‐moisture bales. © 2021 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Investigation of Oil Droplet Breakup during Atomization of Emulsions: Comparison of Pressure Swirl and Twin-Fluid Atomizers

The goal of this study was to investigate oil droplet breakup in food emulsions during atomization with pressure swirl (PS), internal mixing (IM), and external mixing (EM) twin-fluid atomizers. By this, new knowledge is provided that facilitates the design of atomization processes, taking into account atomization performance as well as product characteristics (oil droplet size). Atomization experiments were performed in pilot plant scale at liquid volume flow rates of 21.8, 28.0, and 33.3 L/h. Corresponding liquid pressures in the range of 50–200 bar and air-to-liquid ratios in the range of 0.03–0.5 were applied. Two approaches were followed: oil droplet breakup was initially compared for conditions by which the same spray droplet sizes were achieved at constant liquid throughput. For all volume flow rates, the strongest oil droplet breakup was obtained with the PS nozzle, followed by the IM and the EM twin-fluid atomizer. In a second approach, the concept of energy density EV was used to characterize the sizes of resulting spray droplets and of the dispersed oil droplets in the spray. For all nozzles, Sauter mean diameters of spray and oil droplets showed a power-law dependency on EV. PS nozzles achieved the smallest spray droplet sizes and the strongest oil droplet breakup for a constant EV. In twin-fluid atomizers, the nozzle type (IM or EM) has a significant influence on the resulting oil droplet size, even when the resulting spray droplet size is independent of this nozzle type. Overall, it was shown that the proposed concept of EV allows formulating process functions that simplify the design of atomization processes regarding both spray and oil droplet sizes.

Impact and feasibility of a membrane pre-concentration step in kraft recovery

Emerging robust membrane systems can perform the first section of black liquor (BL) concentration by separating clean water from the black liquor stream using only mechanical pressure. By doing so, they can reduce the steam and energy required for BL concentration. Because of the high osmotic pressure of strong BL, a membrane system would not replace evaporators but would operate in series, performing the first section of BL concentration. In this work, we use a multi-effect evaporator (MEE) model to quantify the steam and energy savings associated with installing membrane systems of different sizes. When maintaining a constant BL solids throughput, we find that a pulp mill could reduce steam usage in its evaporators by up to 65%. Alternatively, a membrane system could also serve to increase BL throughput of the recovery train. We find that a membrane system capable of concentrating BL to 25% could double the BL solids throughput of a mill’s evaporators at the same steam usage. We also demonstrate that installing a membrane system before an MEE would minimally affect key operating parameters such as steam pressures and BL solids concentrations in each effect. This indicates that installing a membrane pre-concentration system would be nonintrusive to a mill’s operations.

Improving Energy Efficiency on SDN Control-Plane Using Multi-Core Controllers

Software-defined networks have become more common in data centers. The programmability of these networks is a great feature that allows innovation to be deployed fast, following the increasing number of new applications. This growth comes with a cost of more processing power and energy consumption. Many researchers have tackled this issue using existing routing techniques to dynamically adjust the network forwarding plane to save energy. On the control-plane, researchers have found algorithms for positioning the controller in a way to reduce the number of used links, thus reducing energy. These strategies reduce energy consumption at the expense of processing power of the controllers. This paper proposes a novel approach to energy efficiency focused on the network’s control-plane, which is complementary to the many already existing data-plane solutions. It takes advantage of the parallel processing capabilities of modern off-the-shelf multicore processors to split the many tasks of the controller among the cores. By dividing the tasks among homogeneous cores, one can lower the frequency of operations, lowering the overall energy consumption while keeping the same quality of service level. We show that a multicore controller can use an off-the-shelf multicore processor to save energy while keeping the level of service. We performed experiments based on standard network measures, namely latency and throughput, and standard energy efficiency metrics for data centers such as the Communication Network Energy Efficiency (CNEE) metric. Higher energy efficiency is achieved by a parallel implementation of the controller and lowering each core’s frequency of operation. In our experiments, we achieved a drop of 28% on processor energy use for a constant throughput scenario when comparing with the single-core approach.

Low Bit-Depth ADCs for Multi-bit Quanta Image Sensors

A 1024 $\times $ 896 test chip is presented in this article to explore a low-power readout circuit for a multi-bit quanta image sensor (QIS). Five well-known analog-to-digital converter (ADC) approaches [flash, pipeline, successive approximation register (SAR), cyclic, and single-slope (SS)] are studied, and two types of ADCs, namely, SAR ADCs and SS ADCs, are implemented in the sensor. The ADC power dissipations are compared under the condition of constant imaging throughput in counting photoelectrons. In QIS devices, one LSB corresponds to one photoelectron. Measurement results show that the power consumption of SAR ADC is better than that of the SS ADC and decreases by a factor of 17 when the resolution is changed from 1 b to 6 bits. By contrast, the power consumption of the SS ADCs decreases by a factor of 2.5. Thus, SAR ADCs seem more suitable for use in low-power multi-bit QIS.

Throughput Sensitivity Analysis in Closed Loop Manufacturing Systems for Hairpin Stator Production

With the development of the electrical vehicle (EV) field, multiple closed loop manufacturing systems (CLMS) handling will have a predominant role in near future industry, since they are used to produce key elements of EVs. Nevertheless, literature for multiple CLMS is not wide and developed. This work is developed from an industrial case of multiple CLMS in EV industry. Through the system analysis, a phenomenon called near flatness (NF) arouse our interest. It identifies the capability of a CLMS to keep a nearly constant throughput when the number of items circulating in the CLMS varies. Further analysis about the relationship between NF and system parameters is carried out. Numerical results, obtained through discrete event simulation, show that NF phenomenon is related to the efficiency in isolation of the machines and the balancing in terms of system processing time. Finally, practical guidelines for multiple CLMS handling, related to NF, are provided.

Decentralized and Secure Communication Architecture for FANETs using Blockchain

Abstract Flying Ad Hoc networks, (FANETs) in recent years, have actively been used in monitoring landscape, military and mapping terrains. However, with the advent of the emerging concept of smart cities and new business applications, these flying devices and drones have found a new use case in the medical and governance sector. But these networks suffer from the major problem of centralization. Although centralization does provide reliability and efficiency but also poses the threat of a single point of failure. Meanwhile, blockchain widely known for its decentralization is heavily researched and can be utilized in this case to offer a solution to the problem of centralization of FANETs. Therefore, in this paper, we propose a decentralized architecture of flying ad hoc nodes based on blockchain and using Practical byzantine fault tolerance (PBFT) for consensus among nodes. By employing PBFT, the architecture is not only computationally efficient and fast. In addition, we have used a gossip protocol for passing messages among nodes. Lastly, we have simulated the working of our model and the experimental results show that the proposed method works with nearly constant throughput and latency while increasing the network size and approximately constant message overhead with increase transaction for given network size.

Achieving High UAV Uplink Throughput by Using Beamforming on Board

High-throughput unmanned aerial vehicle (UAV) communication may unleash the true potential of novel applications for aerial vehicles but also represents a threat for cellular networks due to the high levels of generated interference. In this article, we investigate how a beamforming system installed on board a UAV can be efficiently used to ensure high-throughput uplink UAV communications with minimum impact on the services provided to users on the ground. We study two potential benefits of beamforming, namely, spatial filtering of interference and load balancing, considering different beam switching methodologies. Our analysis is based on system-level simulations followed by a series of measurement campaigns in live Long-Term Evolution (LTE) networks. Our results show that using UAV-side beamforming has a great potential to increase uplink throughput of a UAV while mitigating interference. When beamforming is used, even up to twice as many UAVs may be served within a network compared with UAVs using omni-directional antennas, assuming a constant uplink throughput target. However, to fully exploit the potential of beamforming, a standardized solution ensuring alignment between network operators and UAV manufacturers is required.

An Area-Efficient Variable-Size Fixed-Point DCT Architecture for HEVC Encoding

This paper proposes an area-efficient fixed-point architecture for the computation of the discrete cosine transform (DCT) of multiple sizes in high efficiency video coding (HEVC). This result is obtained by comparing different DCT factorizations in order to find the most suitable one for implementation in the HEVC encoder. The recursive structure of fast algorithms, which decompose the N-point DCT by means of two N/2-point DCTs, is exploited to execute computations of small-size DCTs in parallel, thus maximizing the hardware reusability while maintaining a constant throughput. The simulation results prove that the proposed solution features reduced rate-distortion losses, with relevant complexity saving compared with the state-of-the-art implementations. Finally, the proposed architecture is exploited to design two families of architectures for the 2D-DCT, namely, folded and full-parallel.

The role of far-red spectral states in the energy regulation of phycobilisomes

The main light-harvesting pigment-protein complex of cyanobacteria and certain algae is the phycobilisome, which harvests sunlight and regulates the flow of absorbed energy to provide the photochemical reaction centres with a constant energy throughput. At least two light-driven mechanisms of excited energy quenching in phycobilisomes have been identified: the dominant mechanism in many strains of cyanobacteria depends on the orange carotenoid protein (OCP), while the second mechanism is intrinsically available to a phycobilisome and is possibly activated faster than the former. Recent single molecule spectroscopy studies have shown that far-red (FR) emission states are related to the OCP-dependent mechanism and it was proposed that the second mechanism may involve similar states. In this study, we examined the dynamics of simultaneously measured emission spectra and intensities from a large set of individual phycobilisome complexes from Synechocystis PCC 6803. Our results suggest a direct relationship between FR spectral states and thermal energy dissipating states and can be explained by a single phycobilin pigment in the phycobilisome core acting as the site of both quenching and FR emission likely due to the presence of a charge-transfer state. Our experimental method provides a means to accurately resolve the fluorescence lifetimes and spectra of the FR states, which enabled us to quantify a kinetic model that reproduces most of the experimentally determined properties of the FR states.

Scaling Exponential Backoff

Randomized exponential backoff is a widely deployed technique for coordinating access to a shared resource. A good backoff protocol should, arguably, satisfy three natural properties: (1) it should provide constant throughput, wasting as little time as possible; (2) it should require few failed access attempts, minimizing the amount of wasted effort; and (3) it should be robust, continuing to work efficiently even if some of the access attempts fail for spurious reasons. Unfortunately, exponential backoff has some well-known limitations in two of these areas: it can suffer subconstant throughput under bursty traffic, and it is not robust to adversarial disruption. The goal of this article is to “fix” exponential backoff by making it scalable, particularly focusing on the case where processes arrive in an online, worst-case fashion. We present a relatively simple backoff protocol, R e -B ackoff , that has, at its heart, a version of exponential backoff. It guarantees expected constant throughput with dynamic process arrivals and requires only an expected polylogarithmic number of access attempts per process. R e -B ackoff is also robust to periods where the shared resource is unavailable for a period of time. If it is unavailable for D time slots, R e -B ackoff provides the following guarantees. For n packets, the expected number of access attempts for successfully sending a packet is O (log 2 ( n + D )). For the case of an infinite number of packets, we provide a similar result in terms of the maximum number of processes that are ever in the system concurrently.