High-throughput Channel Research Articles

Intercalation of Fe-montmorillonite for developing nacre-inspired flexible all-solid-state supercapacitor with circular economy approach

The concept of circular economy has gained attention for developing environmentally friendly and sustainable next-generation flexible supercapacitors. Montmorillonite (MMT) has been used to intercalate Fe ions (Fe-MMT) in designing an asymmetric flexible all-solid-state supercapacitor (FASC). The negative electrode was fabricated using PEDOT:PSS, and the positive nanocomposite electrode was made of Fe-MMT, PEDOT:PSS, and PVA, along with a gel electrolyte. Fe-MMT exhibited redox properties, allowing for the reaction of Fe2+/3+/Fe3+ during the charge-discharge cycle, as measured through in-situ X-ray absorption near-edge spectroscopy combined with cyclic-voltammetric measurements. The Fe-MMT nanocomposite exhibited a unique hierarchical nacre-like superstructure, characterized by synchrotron-based transmission X-ray imaging and X-ray diffraction, providing outstanding stability of the charge-discharge cycle under dynamic twisting and high-throughput channels to enhance charge diffusion. The maximum power density achieved was 2181 W kg−1 at 0.83 W h kg−1, and the maximum energy density was 3.27 W h kg−1 at 549 W kg−1. The active cations of the MMT-based electrodes could be further acquired from wastewater recycling, making this an eco-supercapacitor according to the concept of the circular economy. The use of MMT as a cation-exchange material demonstrates its potential for environmentally sustainable energy storage applications.

Guest Editorial: Advances in Parallel Graph Processing: Algorithms, Architectures, and Application Frameworks

The papers in this special section explore recent advancements in parallel graph processing. In the sphere of modern data science and data-driven applications, graph algorithms have achieved a pivotal place in advancing the state of scientific discovery and knowledge. Nearly three centuries of ideas have made graph theory and its applications a mature area in computational sciences. Yet, today we find ourselves at a crossroads between theory and application. Spurred by the digital revolution, data from a diverse range of high throughput channels and devices, from across internet-scale applications, are starting to mark a new era in data-driven computing and discovery. Building robust graph models and implementing scalable graph application frameworks in the context of this new era are proving to be significant challenges. Concomitant to the digital revolution, we have also experienced an explosion in computing architectures, with a broad range of multicores, manycores, heterogeneous platforms, and hardware accelerators (CPUs, GPUs) being actively developed and deployed within servers and multinode clusters. Recent advances have started to show that in more than one way, these two fields—graph theory and architectures–are capable of benefiting and in fact spurring new research directions in one another. This special section is aimed at introducing some of the new avenues of cutting-edge research happening at the intersection of graph algorithm design and their implementation on advanced parallel architectures.

Inclusion of connate water in enhanced gas recovery reservoir simulations

Enhanced natural gas recovery (EGR) with supercritical (sc)CO2 sequestration offers the prospect of increased natural gas recovery. High-fidelity reservoir simulations offer a method to quantify the risk of contamination of produced gas by the injected scCO2. Simulations of scCO2 mixing with the reservoir gas have been reported; however the effects of connate water on EGR have not been effectively explored. We extend a prior EGR simulation tool (Patel, May and Johns, 2016; Ref. [1]) to incorporate connate water accounting for its effect on dispersivity and permeability; chemical equilibrium is modelled using a novel, computationally efficient Lagrange multiplier-based approach.The code is applied to a ‘quarter five-spot’ benchmark scenario. The inclusion of connate water generally resulted in a reduction in breakthrough time and a decrease in methane recovery. The connate water's largest effect was to change the scCO2 flow field, which sank towards the reservoir floor, flooded the lowermost accessible layers and entered the production well via a high throughput channel (‘coning’). The magnitude of these effects were, however, sensitive to well perforation depth, the influence of which was subsequently studied systematically. Well perforation depth was found to determine the duration of these sinking and coning events in a non-linear manner.

Microparticle trajectories in a high-throughput channel for contact-free fractionation by dielectrophoresis

Continuous, contact-free fractionation of sensitive microparticles at high throughput is a challenge. For this purpose, we developed a sheath flow assisted dielectrophoretic (DEP) field-flow separator with a tailored arrangement of cylindrical interdigitated electrodes (cIDE) and observed size-dependent trajectories of dispersed particles. Using a voltage input of 200Veff at a frequency of 200kHz, polystyrene particles (45, 25, and 11µm in diameter) levitated to different heights along the channel length due to a negative DEP force. Experimental observations agree well with simulated particle trajectories that were obtained by a modified Lagrangian particle tracking model in combination with Laplace's and Navier–Stokes equations. By exploiting the size-dependent levitation height difference the desired particle size fraction can be collected at a specific channel length. The required channel length of the proposed cIDE separator increases with decreasing particle size to be separated. The quality of theoretical fractionation, which we quantify by resolution, improves strongly with reduced collector width, reduced volume flow rate and increased voltage input. The sensitivity of these dependencies increases with decreasing particle size. We calculated a theoretical throughput of up to 47mLmin−1 when trading-off design and operation parameters, allowing for contact-free fractionation of sensitive microparticles with negligible shear stress.

Interference-aware high-throughput channel allocation mechanism for CR-VANETs

The incorporation of cognitive radio (CR) technology in vehicular ad hoc networks (VANETs) has given birth to a new network, namely CR-VANET, which facilitates the vehicular network to achieve communication efficiency in many resource-demanding applications including video and audio streaming, collision warning, gaming, etc. One of the primary challenges in this CR-VANET network is to allocate high-throughput licensed channels to the application requests in face of interference between the primary users (PUs) and the secondary users (SUs) and among the SUs on the channels. In this paper, we address the channel allocation problem in CR-VANET with the objective of system-wide throughput maximization while maintaining the application quality-of-service (QoS) requirements in terms of channel throughput and packet delivery delay for data transmission. We develop conflict graphs of link-band pairs to describe the interference relationship among source-destination vehicle pairs on different channels and determine independent sets of vehicle pairs that can communicate simultaneously to maximize the spatial reuse of the licensed channels. Finally, we formulate a high-throughput channel allocation problem as a mixed-integer linear programming (MILP) problem. Through extensive simulations, we demonstrate that the proposed interference-aware high-throughput channel allocation mechanism (HT-CAM) provides with better network performances compared to state-of-the-art protocols.

LoadingZones

Internet connectivity is nowadays an ubiquitous service. However, on the road we obtain access using costly and limited data cellular network subscriptions. This, along with significant network congestion, severely limits network use. Opportunistic access to indoor APs is limited by three factors. First, establishing a link to an AP requires a significant amount of time, and, second, links on the street usually have poor quality. Third, the lifetime of this link is very short in a moving car, due to indoor APs generally covering small areas of the street. Combined, these factors thwart opportunistic use of APs for Internet access. In this paper, we propose a novel approach that leverages the large number of parked cars to separate these three factors and tackle them independently: a parked car can connect to an AP with a link that, despite its poor quality, has a long lifetime. A moving vehicle can instead benefit from the better link with a parked car and use it as a relay. As our experiments show, our approach enables the use of this free, high throughput channel for a number of non time-sensitive applications, thus reducing cost and the load on the cellular network.

Using Transmission Lines for Global On-Chip Communication

The growing number of cores in chip multiprocessors increases the importance of interconnection for overall system performance and energy efficiency. Compared to traditional distributed shared-memory architectures, chip-multiprocessors (CMPs) offer a different set of design constraints and opportunities. As a result, a conventional packet-relay multiprocessor interconnect architecture is a valid, but not necessarily optimal, design point. Worsening wire delays, energy-inefficient routers, and the decreased importance of in-field scalability, make the conventional packet-switched network-on-chip a less attractive option. An alternative solution uses well-engineered transmission lines as communication links. These transmission lines, along with simple, practical circuits using modern complementary metal-oxide-semiconductor technology, can provide low latency, low energy, high throughput channels which can be used as a shared-medium point-to-point link. The design of the transmission lines and transceiver circuits has important architectural impact. This paper includes a first-step design effort for these components, particularly when used for a globally shared-medium bus. For medium-scale CMPs, this interconnect backbone can eliminate the need for packet switching and provide energy, as well as performance benefits when compared to a conventional mesh interconnect. We will provide a design of such a system from the ground up, including design of the transmission lines, transceiver circuits, and a simple, yet effective, architectural design for a shared-medium interconnect, and show that such a design can be a compelling alternative to packet-switched networks for CMPs.

Strong-Incentive, High-Throughput Channel Assignment for Noncooperative Wireless Networks

Channel assignment is a very important topic in wireless networks. In this paper, we study FDMA channel assignment in a noncooperative wireless network, where devices are selfish. Existing work on this problem has considered Nash Equilibrium (NE), which is not a very strong solution concept and may not guarantee a good system performance. In contrast, in this work, we introduce a payment formula to ensure the existence of a Strongly Dominant Strategy Equilibrium (SDSE), a different solution concept that gives participants much stronger incentives. We show that, when the system converges to an SDSE, it also achieves global optimality in terms of system throughput. Furthermore, we extend our work to the case in which some radios have a limited tunability. We show that in such a case, nevertheless, it is generally impossible to have a similar SDSE solution; with additional assumptions on the numbers of radios and the types of channels, etc., we can again achieve an SDSE solution that guarantees optimal system throughput. Besides this extension, we also consider other extensions of our strategic game to achieve throughput fairness and to deal with possibly inconsistent information caused by players joining and leaving. Finally, we evaluate our design with simulated experiments. Numerical results verify that the system does converge to the globally optimal channel assignment with the proposed payment formula, and that the system throughput is significantly higher than that achievable with the random-based and NE-based channel assignment schemes.

High-throughput channel arrays for inhibitor testing: Proof of concept for AA2024-T3

A high-throughput test has been developed for screening aqueous corrosion inhibitors on aluminium AA2024-T3. The method adapts basic microfluidic technology to create multiple channels in polydimethylsiloxane, which allow solutions to flow over the surface of the alloy, causing severe corrosion within hours if no inhibitor is present. In three-channel experiments under various channel conditions, corrosion rates were accelerated up to 15 times when compared to standard immersion tests. In addition, 10-channel experiments were conducted to simultaneously test 10 different inhibitors, and the results were compared visually and to actual corrosion results obtained quantitatively via solution analyses.

Communication Limits Due to Photon Detector Jitter

Detector jitter, the random delay from the time a photon is incident on a single-photon-counting detector (SPD) to the time an electrical pulse is produced in response to that photon, is characterized for a number of SPDs. The jitter is modeled as a weighted sum of Gaussians. The performance in detector jitter is measured by determining the capacity of a communications channel utilizing a given detector. It is observed that the loss, measured as the ratio of the signal power required to achieve a specified capacity in the presence of jitter to that in the absence of jitter, goes as the square of the normalized jitter standard deviation (the standard deviation of the jitter in slotwidths). The loss is small when the normalized jitter is less than one, and becomes significant beyond that point. This loss must be taken into account when evaluating detectors for very high throughput channels.