227 research outputs found

    Generalized Hilbert Operator Acting on Bloch Type Spaces

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    Let μ\mu be a positive Borel measure on the interval [0,1). For α>0\alpha>0, the Hankel matrix Hμ,α=(μn,k,α)n,k0\mathcal{H}_{\mu,\alpha}=(\mu_{n,k,\alpha})_{n,k\geq 0} with entries μn,k,α=[0,1)Γ(n+α)n!Γ(α)tn+kdμ(t)\mu_{n,k,\alpha}=\int_{[0,1)}\frac{\Gamma(n+\alpha)}{n!\Gamma(\alpha)}t^{n+k}d\mu(t) formally induces the operator Hμ,α(f)(z)=n=0(k=0μn,k,αak)zn\mathcal{H}_{\mu,\alpha}(f)(z)=\sum_{n=0}^{\infty}\left(\sum_{k=0}^{\infty} \mu_{n, k,\alpha} a_{k}\right)z^{n} on the space of all analytic functions f(z)=k=0akzkf(z)=\sum_{k=0}^{\infty}a_{k}z^{k} in the unit disc D\mathbb{D}. In this paper, we characterize the measures μ\mu for which Hμ,α\mathcal{H}_{\mu,\alpha} (α2\alpha\geq 2) is a bounded (resp., compact) operator from the Bloch type space Bβ\mathscr{B}_{\beta} (0<β<0<\beta<\infty) into Bα1\mathscr{B}_{\alpha-1}. We also give a necessary condition for which Hμ,α\mathcal{H}_{\mu,\alpha} is a bounded operator by acting on Bloch type spaces for general cases

    A permeability model for the hydraulic fracture filled with proppant packs under combined effect of compaction and embedment

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    The authors acknowledge the financial support from Science Foundation of China University of Petroleum, Beijing (No. 2462014YJRC060 and No.2462014YJRC059)Peer reviewedPostprin

    Pretraining in Deep Reinforcement Learning: A Survey

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    The past few years have seen rapid progress in combining reinforcement learning (RL) with deep learning. Various breakthroughs ranging from games to robotics have spurred the interest in designing sophisticated RL algorithms and systems. However, the prevailing workflow in RL is to learn tabula rasa, which may incur computational inefficiency. This precludes continuous deployment of RL algorithms and potentially excludes researchers without large-scale computing resources. In many other areas of machine learning, the pretraining paradigm has shown to be effective in acquiring transferable knowledge, which can be utilized for a variety of downstream tasks. Recently, we saw a surge of interest in Pretraining for Deep RL with promising results. However, much of the research has been based on different experimental settings. Due to the nature of RL, pretraining in this field is faced with unique challenges and hence requires new design principles. In this survey, we seek to systematically review existing works in pretraining for deep reinforcement learning, provide a taxonomy of these methods, discuss each sub-field, and bring attention to open problems and future directions

    GPUMemSort: A High Performance Graphics Co-processors Sorting Algorithm for Large Scale In-Memory Data

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    In this paper, we present a GPU-based sorting algorithm,GPUMemSort, which achieves high performance insorting large-scale in-memory data by take advantage ofGPU processors. It consists of two algorithms: an in-corealgorithm, which is responsible for sorting data in GPUglobal memory efficiently, and an out-of-core algorithm,which is responsible for dividing large-scale data intomultiple chunks that fit GPU global memory.GPUMemSort is implemented based on NVIDIA’s CUDAframework and some critical and detailed optimizationmethods are also presented. The tests of differentalgorithms have been run on multiple data sets. Theexperimental results show that our in-core sorting canoutperform other comparison-based algorithms andGPUMemSort is highly effective in sorting large-scale inmemorydata

    A New Architecture for Application-aware Cognitive Multihop Wireless Networks

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    In this article, we propose a new architecture for AC-MWN. Cognitive radio is a technique to adaptively use the spectrum so that the resource can be used more efficiently in a low-cost way. A multihop wireless network can be deployed quickly and flexibly without fixed infrastructure. In our proposed new architecture, we study backbone routing schemes with network cognition, and a routing scheme with network coding and spectrum adaptation. A testbed is implemented to test the proposed schemes for AC-MWN. In addition to basic measurements, we implement a video streaming application based on the proposed AC-MWN architecture using cognitive radios. Preliminary results demonstrate that the proposed AC-MWN is applicable, and is valuable for future low-cost and flexible communication networks
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