22,290 research outputs found
On some universal sums of generalized polygonal numbers
For those with are
called generalized -gonal numbers. Sun [13] studied for what values of
positive integers the sum is universal over (i.e., any has the form
with ). We prove that
and are universal over , as conjectured by Sun. Sun also conjectured that any can be
written as and with
; in contrast, we show that and
are universal over . Our proofs are essentially
elementary and hence suitable for general readers.Comment: Final published versio
Thermoelectric DC conductivities with momentum dissipation from higher derivative gravity
We present a mechanism of momentum relaxation in higher derivative gravity by
adding linear scalar fields to the Gauss-Bonnet theory. We analytically
computed all of the DC thermoelectric conductivities in this theory by adopting
the method given by Donos and Gauntlett in [arXiv:1406.4742]. The results show
that the DC electric conductivity is not a monotonic function of the effective
impurity parameter : in the small limit, the DC conductivity is
dominated by the coherent phase, while for larger , pair creation
contribution to the conductivity becomes dominant, signaling an incoherent
phase. In addition, the DC heat conductivity is found independent of the
Gauss-Bonnet coupling constant.Comment: 1+19 pages, 2 figures,typos in Eq.(40) correcte
3E: Energy-Efficient Elastic Scheduling for Independent Tasks in Heterogeneous Computing Systems
Reducing energy consumption is a major design constraint for modern heterogeneous computing systems to minimize electricity cost, improve system reliability and protect environment. Conventional energy-efficient scheduling strategies developed on these systems do not sufficiently exploit the system elasticity and adaptability for maximum energy savings, and do not simultaneously take account of user expected finish time. In this paper, we develop a novel scheduling strategy named energy-efficient elastic (3E) scheduling for aperiodic, independent and non-real-time tasks with user expected finish times on DVFS-enabled heterogeneous computing systems. The 3E strategy adjusts processorsβ supply voltages and frequencies according to the system workload, and makes trade-offs between energy consumption and user expected finish times. Compared with other energy-efficient strategies, 3E significantly improves the scheduling quality and effectively enhances the system elasticity
Authorship Attribution Using a Neural Network Language Model
In practice, training language models for individual authors is often
expensive because of limited data resources. In such cases, Neural Network
Language Models (NNLMs), generally outperform the traditional non-parametric
N-gram models. Here we investigate the performance of a feed-forward NNLM on an
authorship attribution problem, with moderate author set size and relatively
limited data. We also consider how the text topics impact performance. Compared
with a well-constructed N-gram baseline method with Kneser-Ney smoothing, the
proposed method achieves nearly 2:5% reduction in perplexity and increases
author classification accuracy by 3:43% on average, given as few as 5 test
sentences. The performance is very competitive with the state of the art in
terms of accuracy and demand on test data. The source code, preprocessed
datasets, a detailed description of the methodology and results are available
at https://github.com/zge/authorship-attribution.Comment: Proceedings of the 30th AAAI Conference on Artificial Intelligence
(AAAI'16
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Photodissociation Dynamics of Free Radicals Using High-n Rydberg Atom Time-of-Flight Spectroscopy
Free radicals are open-shell systems that have one or more unpaired valence electrons, and are thus short-lived and highly reactive. Free radicals can be found as important reactive intermediates in a wide range of chemical environments, for example, combustion, atmospheric chemistry, plasma, and interstellar chemistry. The photodissociation studies of free radicals can provide spectroscopic and electronic excited state information of free radicals, probe excited-state potential energy surfaces (PESs), their interactions, and their influence on reaction dynamics, and provide benchmarks for theoretical studies of the open-shell systems. The photodissociation dynamics of free radicals were studied using the high-n Rydberg H-atom time-of-flight technique. Several systems were investigated in the dissertation. The hydroxyl radical (OH), which is a prototypical diatomic radical, has been examined via several rovibrational levels in the A2Ξ£+ state. The H + O(3PJ) product branching ratios and angular distributions from the A2Ξ£+ state were obtained. Sequential two-photon excitations to the 22Π and B2Ξ£+ repulsive states were observed, leading to the H + O(1D) and H + O(1S) products, respectively. Ultraviolet (UV) photodissociation of a series of alkyl radicals, ethyl (C2H5), n-butyl (n-C4H9), i-butyl (i-C4H9), t-butyl (t-C4H9), and 1-pentyl (1-C5H11), via their Rydberg states were observed to have two main dissociation channels: (i) direct dissociation from the electronic excited state, and (ii) unimolecular dissociation after internal conversion from the electronic excited state to the ground state. 2-Propenyl radical (CH2CCH3), in the alkenyl category, undergoes unimolecular dissociation on the ground electronic state following the UV photoexcitation and internal conversion from the excited state. Vinoxy radical (CH2CHO) is a prototypical unsaturated alkoxy radical. After photoexcitation to the B Μ2A" state, the vinoxy radical undergoes unimolecular dissociation following internal conversion to the ground state (X Μ2A") and the first excited state (A Μ2A'). The UV photodissociation of thiomethoxyl radical (CH3S), a sulfur system, is similar to that of the ethyl radical and has two main channels: (i) direct dissociation on the repulsive PES, and (ii) unimolecular dissociation after internal conversion from the electronic excited state to the ground electronic state
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