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181.
A Pd/C‐CeO2 Anode Catalyst for High‐Performance Platinum‐Free Anion Exchange Membrane Fuel Cells
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Dr. Hamish A. Miller Dr. Alessandro Lavacchi Dr. Francesco Vizza Dr. Marcello Marelli Dr. Francesco Di Benedetto Dr. Francesco D'Acapito Yair Paska Miles Page Dr. Dario R. Dekel 《Angewandte Chemie (International ed. in English)》2016,55(20):6004-6007
One of the biggest obstacles to the dissemination of fuel cells is their cost, a large part of which is due to platinum (Pt) electrocatalysts. Complete removal of Pt is a difficult if not impossible task for proton exchange membrane fuel cells (PEM‐FCs). The anion exchange membrane fuel cell (AEM‐FC) has long been proposed as a solution as non‐Pt metals may be employed. Despite this, few examples of Pt‐free AEM‐FCs have been demonstrated with modest power output. The main obstacle preventing the realization of a high power density Pt‐free AEM‐FC is sluggish hydrogen oxidation (HOR) kinetics of the anode catalyst. Here we describe a Pt‐free AEM‐FC that employs a mixed carbon‐CeO2 supported palladium (Pd) anode catalyst that exhibits enhanced kinetics for the HOR. AEM‐FC tests run on dry H2 and pure air show peak power densities of more than 500 mW cm?2. 相似文献
182.
Moran Balaish Prof. Emanuel Peled Prof. Diana Golodnitsky Prof. Yair Ein‐Eli 《Angewandte Chemie (International ed. in English)》2015,54(2):436-440
Non‐aqueous lithium–oxygen batteries are considered as most advanced power sources, albeit they are facing numerous challenges concerning almost each cell component. Herein, we diverge from the conventional and traditional liquid‐based non‐aqueous Li–O2 batteries to a Li–O2 system based on a solid polymer electrolyte (SPE‐) and operated at a temperature higher than the melting point of the polymer electrolyte, where useful and most applicable conductivity values are easily achieved. The proposed SPE‐based Li‐O2 cell is compared to Li–O2 cells based on ethylene glycol dimethyl ether (glyme) through potentiodynamic and galvanostatic studies, showing a higher cell discharge voltage by 80 mV and most significantly, a charge voltage lower by 400 mV. The solid‐state battery demonstrated a comparable discharge‐specific capacity to glyme‐based Li–O2 cells when discharged at the same current density. The results shown here demonstrate that the safer PEO‐based Li–O2 battery is highly advantageous and can potentially replace the contingent of liquid‐based cells upon further investigation. 相似文献
183.
We study finite convergence of the modified cyclic subgradient projections (MCSP) algorithm for the convex feasibility problem
(CFP) in the Euclidean space. Expanding control sequences allow the indices of the sets of the CFP to re-appear and be used
again by the algorithm within windows of iteration indices whose lengths are not constant but may increase without bound.
Motivated by another development in finitely convergent sequential algorithms that has a significant real-world application
in the field of radiation therapy treatment planning, we show that the MCSP algorithm retains its finite convergence when
used with an expanding control that is repetitive and fulfills an additional condition. 相似文献
184.
Isocyanate-terminated polyethylene oxide (PEO) was prepared by reaction of hydroxyl-terminated PEO of different molecular weights and toluene diisocyanate (TDI), at a molar ratio of 1:2. Reaction was carried out with and without catalyst (dibutyltin dilaurate). When catalyst was used, some chain extension accompanied the endcapping reaction. When endcapping reaction was carried out without catalyst, chain extension was minimal as determined from endgroup analysis and viscosity measurements. It was also found that secondary reactions of the terminal isocyanate groups led to further increase in solution viscosity after completion of the endcapping reaction. 相似文献
185.
Let G be a bipartite graph, with k|e(G). The zero-sum bipartite Ramsey number B(G, Zk) is the smallest integer t such that in every Zk-coloring of the edges of Kt,t, there is a zero-sum mod k copy of G in Kt,t. In this article we give the first proof that determines B(G, Z2) for all possible bipartite graphs G. In fact, we prove a much more general result from which B(G, Z2) can be deduced: Let G be a (not necessarily connected) bipartite graph, which can be embedded in Kn,n, and let F be a field. A function f : E(Kn,n) → F is called G-stable if every copy of G in Kn,n has the same weight (the weight of a copy is the sum of the values of f on its edges). The set of all G-stable functions, denoted by U(G, Kn,n, F) is a linear space, which is called the Kn,n uniformity space of G over F. We determine U(G, Kn,n, F) and its dimension, for all G, n and F. Utilizing this result in the case F = Z2, we can compute B(G, Z2), for all bipartite graphs G. © 1998 John Wiley & Sons, Inc. J. Graph Theory 29: 151–166, 1998 相似文献
186.
Let M be a compact 3-manifold whose interior admits a complete hyperbolic structure. We let Λ(M) be the supremum of λ0(N) where N varies over all hyperbolic 3-manifolds homeomorphic to the interior of N. Similarly, we let D(M) be the infimum
of the Hausdorff dimensions of limit sets of Kleinian groups whose quotients are homeomorphic to the interior of M. We observe
that A(M) = D(M)(2 − D(M)) if M is not handlebody or a thickened torus. We characterize exactly when A(M) = 1 and D(M) = 1
in terms of the characteristic submanifold of the incompressible core of M. 相似文献
187.
Yair Caro 《Archiv der Mathematik》1989,52(3):289-297
188.
Yair Tauman 《Israel Journal of Mathematics》1982,43(1):75-96
We give a complete characterization of games inpNA of the formf
o μ (where μ is a vector of finite number of non-atomic probability measures, andf is a real valued function on the range of μ withf(0)=0). Specifically, we show thatf
o μ is inpNA iff “f is continuous at μ” (the definition of the latter is given in the paper).
This work was supported by National Science Foundation Grant SOC 75-21820-A01 at the Institute for Mathematical Studies in
the Social Sciences, Stanford University. 相似文献
189.
High resolution analysis of voiced speech signals in Parkinsonian patients using a pitch synchronous pole-zero model is introduced. A modified estimation error is defined leading to an accurate and consistent determination of the excitation instants of the model. An infinite resolution in determining these instants, despite the finite sampling interval, is achieved by mapping the discrete (digitized) problem into a continuous one. The proposed analysis was found to be useful in analyzing Parkinsonian speech where the goal was to detect and quantify the Parkinsonian tremor and rigidity from sustained voiced sounds. 相似文献
190.
A general primal—dual algorithm for linearly constrained optimization problems is formulated in which the dual variables are updated by a dual algorithmic operator. Convergence is proved under the assumption that the dual algorithmic operator implies asymptotic feasibility of the primal iterates with respect to the linear constraints. A general result relating the minimal values of an infinite sequence of constrained problems to the minimal value of a limiting problem (constrained by the limit of the sequence of constraints sets) is established and invoked. The applicability of the general theory is demonstrated by analyzing a specific dual algorithmic operator. This leads to the MART algorithm for constrained entropy maximization used in image reconstruction from projections. 相似文献