841 research outputs found
Electrochemical transport in CuCl/HCl(aq) electrolyzer cells and stack of the Cu–Cl cycle
No full textThis paper develops a comprehensive predictive model for the CuCl/HCl(aq) electrolyzer stack in the electrochemical unit of the Cu–Cl cycle of hydrogen production. A strong aqueous anolyte is fed into the stack and forms complex speciation. The unit single cell is modeled to predict the decomposition voltage by applying the Gibbs energy minimization method (GEM). The kinetic correlations are incorporated to take into account the overpotential losses during the hydrogen generation process under a non-equilibrium condition with the stack under potential. To evaluate the single-cell contribution to the average performance of stack, a hydrodynamic analysis reveals the anolyte and catholyte flow distribution using a finite element method for solutions of the equation of mass and momentum conservation equations of the flow field. Using the simulated stack, the voltage spread across the individual cells in the stack, cell and stack voltage efficiency, and the sensitivity of stack performance under the operating conditions, are investigated. It is shown that the speciation model has good agreement with data in past literature. With an increase in the stack operating temperature from 25 °C to 65 °C, the average stack efficiency improves from 68% to 72%. Cells close to the anolyte or catholyte input ports possess a higher voltage efficiency than other cells. This is mainly due to less electrolyte received by the cells placed in the middle of the stack for the X-shape bipolar modules, resulting in less decomposition potential
Design and Evaluation of a novel holding stack management tool
No full textBefore an aircraft enters the Terminal Manoeuvring Area (TMA) a delay may need to be introduced due to capacity limits. An Air Traffic Controller (ATCo) has the opportunity to introduce a holding procedure. When multiple aircraft need to be delayed in this form a holding stack may be formed. This holding stack is formed above the Initial Approach Fix (IAF). Current industry standard is able to achieve an accuracy within two minutes of planned Estimated Approach Time (EAT), at which the aircraft is planned to fly over the IAF and proceed to the TMA. In this research a display tool to aid Area Controllers (ACC) in realising a more accurate delivery and improving their situational awareness is designed, called the Stack Planner (SP). The SP assists controllers with choosing an optimal holding leg time for aircraft in the holding stack to adjust their IAF flyover time. The display aims to assist ATCo by showing the possible space of their control actions as well as system constraints. In an initial proof-of-concept experiment, comparing the SP display with a baseline state of the art display, promising results are found; the SP display shows a more manageable workload with increased situational awareness that scales with scenario complexity. The new display also shows the potential to move from minute accuracy to second accuracy. Future studies would need to investigate the extent to which scenario complexity plays a role in accuracy of delivery for both baseline and SP displays.Aerospace Engineerin
Anna C. Wilson - 210216 About 1919
No full textThe wooden passenger steamer "Anna C. Wilson", built in 1912, sailed between Grand Haven and Saugatuck, Michigan. Constructed with one stack, as shown here, the ship was modified by her final owner, Edward Hinz. He added a dummy second stack when he bought her in 1931
A proposed mechanism for super-pipelined instruction-issue for ILP stack
No full textA resurgence of interest in hardware stack-machine architectures, in which an implicitly addressed operand stack mode of computation is used, has followed closely in the wake of the growth of Java technology. However hardware for direct execution of stack-based machine level operations suffer from a lack of development in areas of advanced machine architecture, in particular where instruction-level parallelism is concerned. In this paper the author proposes a mechanism for super-pipelined issue of stack-based instructions to support an in-order issue policy with out-of-order completion, and introduces some preliminary results in order to illustrate possible trade-offs and issues likely to be valuable focal points for a full performance assessment in future work
Node-indri: Moving the indri toolkit to the modern web stack
No full textWe introduce node-indri, a Node.js module that acts as a wrapper around the Indri toolkit, and thus makes an established IR toolkit accessible to the modern web stack. node-indri exposes many of Indri’s functionalities and provides direct access to document content and retrieval scores for web development (in contrast to, for instance, the Pyndri wrapper). This setup reduces the amount of glue code that has to be developed and maintained when researching search interfaces, which today tend to be developed with specific JavaScript libraries such as React.js, Angular.js or Vue.js. The node-indri repository is open-sourced at https://github.com/felipemoraes/node-indri.Web Information System
An overview of median and stack filtering
No full textWithin the last two decades a small group of researchers has built a useful, nontrivial theory of nonlinear signal processing around the median-related filters known as rank-order filters, order-statistic filters, weighted median filters, and stack filters. This required significant effort to overcome the bias, both in education and research, toward linear theory, which has been dominant since the days of Fourier, Laplace, and
Multimode resistive switching in nanoscale hafnium oxide stack as studied by atomic force microscopy
No full textThe nanoscale resistive switching in hafnium oxide stack is investigated by the conductive atomic force microscopy (C-AFM). The initial oxide stack is insulating and electrical stress from the C-AFM tip induces nanometric conductive filaments. Multimode resistive switching can be observed in consecutive operation cycles at one spot. The different modes are interpreted in the framework of a low defect quantum point contact theory. The model implies that the optimization of the conductive filament active region is crucial for the future application of nanoscale resistive switching devices. Published by AIP Publishing.NSFC [61376084, 61421005, 61334007]; Beijing Municipal Science and Technology Plan Projects [Z151100000915071]; IMEC's industrial affiliation program on RRAM; China Scholarship Council (CSC)SCI(E)[email protected]; [email protected]
Light field reconstruction from projection modeling of focal stack
No full textThis paper aims to reconstruct the object-side light field from the focal stack focusing on different imaging planes. In the forward problem, the focal stack was modeled as projections of the light field. Based on projection modeling, both the filtered-backprojection(FBP) method and the Landweber iterative scheme of solving the inverse problem regarding light field reconstruction from focal stack were derived by applying the methods of computerized tomography(CT). The experimental results show that the high-precision light field can be reconstructed via FBP and Simultaneous-Algebraic-Reconstruction-Technique(SART) algorithm, and depth and surface of the scene can be reconstructed via the reconstructed light field. (C) 2017 Optical Society of AmericaNational Basic Research Program of China (973 Program) [2015CB351803]; National Science Foundation of China [61372150, 61421062, 61520106004]; Sino-German Center [GZ 1025]SCI(E)ARTICLE1011377-113882
Will Quantum Computers Scale without Inter-Chip Comms? A Structured Design Exploration to the Monolithic vs Distributed Architectures Quest
No full textBeing a very promising technology, with impressive advances in the recent years, it is still unclear how quantum computing will scale to satisfy the requirements of its most powerful applications. Although continued progress in the fabrication and control of qubits is required, quantum computing scalability will depend as well on a comprehensive architectural design considering a distributed multi-core approach as an alternative to the traditional monolithic version, hence including a communications perspective. However, this goes beyond introducing mere interconnects. Rather, it implies consolidating the full communications stack in the quantum computer structure. In this paper, we propose a double full-stack architecture encompassing quantum computation and quantum communications, which we use to address the monolithic versus distributed question with a structured design methodology. For that, we revisit the different quantum computing layers to capture and model their essence by highlighting the open design variables and performance metrics. Using behavioral models and actual measurements from existing quantum computers, the results of simulations suggest that multicore architectures may effectively unleash the full quantum computer potential.Accepted Author ManuscriptQCD/Almudever La
Degradation study of a reversible solid oxide cell (rSOC) short stack using distribution of relaxation times (DRT) analysis
No full textReversible solid oxide cells (rSOC) can convert excess electricity to valuable fuels in electrolysis cell mode (SOEC) and reverse the reaction in fuel cell mode (SOFC). In this work, a five - cell rSOC short stack, integrating fuel electrode (Ni-YSZ) supported solid oxide cells (Ni-YSZ parallel to YSZ vertical bar CGO parallel to LSC-CGO) with an active area of 100 cm(2), is tested for cyclic durability. The fuel electrode gases of H-2/N-2:50/50 and H-2/H2O:20/80 in SOFC and SOEC mode, respectively, are used during the 35 reversible operations. The voltage degradation of the rSOC is 1.64% kh(-1) and 0.65% kh(-1) in SOFC and SOEC mode, respectively, with fuel and steam utilisation of 52%. The post-cycle steady-state SOEC degradation of 0.74% kh(-1) suggests improved lifetime during rSOC conditions. The distribution of relaxation times (DRT) analysis suggests charge transfer through the fuel electrode is responsible for the observed degradation. (C) 2022 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.SCI-STI-JV
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