18,580 research outputs found
Ge Nanowires Anode sheathed with Amorphous Carbon for Rechargeable Lithium batteries
Interdisciplinary School of Green EnergyThe composite electrode composed of single crystalline Ge NWs sheathed with amorphous carbon showed excellent electrochemical properties of large reversible capacity, high coulombic efficiency, excellent rate capability and stable cycle performance. c-Ge NWs synthesized by using thermal decomposition of C2H2 gas at 700 °C under Ar atmosphere after SLS (solution-liquid-solid) growth were found to have good performance during cycling with Li. The rate capability for charging was shown reversible capacity of 963 mAh/g with a coulombic efficiency of 90% and 700 mAh/g at the rate of 6C (= 4800mA/g). Capacity retention after 100 cycles was 72% at the rate of 0.5C. The improved electrochemical performance of c-Ge-NWs fabricated in our experiment was attributed to the formation of amorphous Ge NWs during cycling and a homogenous carbon coating on Ge NWs. Thus, these results suggest that the use of nanowires structure can be promising for alloy anode materials in lithium ion batteries
Dirichlet series of Rankin-Cohen Brackets
Given modular forms and of weights and , respectively,
their Rankin-Cohen bracket corresponding to a nonnegative
integer is a modular form of weight , and it is given as a
linear combination of the products of the form for . We use a correspondence between quasimodular forms and sequences of
modular forms to express the Dirichlet series of a product of derivatives of
modular forms as a linear combination of the Dirichlet series of Rankin-Cohen
brackets
A perturbative approach to a class of Fokker-Planck equations
In this paper we present a direct perturbative method to solving certain
Fokker-Planck equations, which have constant diffusion coefficients and some
small parameters in the drift coefficients. The method makes use of the
connection between the Fokker-Planck and Schr\"odinger equations. Two examples
are used to illustrate the method. In the first example the drift coefficient
depends only on time but not on space. In the second example we consider the
Uhlenbeck-Ornstein process with a small drift coefficient. These examples show
that the such perturbative approach can be a useful tool to obtain approximate
solutions of Fokker-Planck equations with constant diffusion coefficients.Comment: 5 pages, no figure
DeepStory: Video Story QA by Deep Embedded Memory Networks
Question-answering (QA) on video contents is a significant challenge for
achieving human-level intelligence as it involves both vision and language in
real-world settings. Here we demonstrate the possibility of an AI agent
performing video story QA by learning from a large amount of cartoon videos. We
develop a video-story learning model, i.e. Deep Embedded Memory Networks
(DEMN), to reconstruct stories from a joint scene-dialogue video stream using a
latent embedding space of observed data. The video stories are stored in a
long-term memory component. For a given question, an LSTM-based attention model
uses the long-term memory to recall the best question-story-answer triplet by
focusing on specific words containing key information. We trained the DEMN on a
novel QA dataset of children's cartoon video series, Pororo. The dataset
contains 16,066 scene-dialogue pairs of 20.5-hour videos, 27,328 fine-grained
sentences for scene description, and 8,913 story-related QA pairs. Our
experimental results show that the DEMN outperforms other QA models. This is
mainly due to 1) the reconstruction of video stories in a scene-dialogue
combined form that utilize the latent embedding and 2) attention. DEMN also
achieved state-of-the-art results on the MovieQA benchmark.Comment: 7 pages, accepted for IJCAI 201
Tilings of the Sphere by Edge Congruent Pentagons
We study edge-to-edge tilings of the sphere by edge congruent pentagons,
under the assumption that there are tiles with all vertices having degree 3. We
develop the technique of neighborhood tilings and apply the technique to
completely classify edge congruent earth map tilings.Comment: 36 pages, 34 figure
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