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971.
Quantum Bayesian computation is an emerging field that levers the computational gains available from quantum computers. They promise to provide an exponential speed-up in Bayesian computation. Our article adds to the literature in three ways. First, we describe how quantum von Neumann measurement provides quantum versions of popular machine learning algorithms such as Markov chain Monte Carlo and deep learning that are fundamental to Bayesian learning. Second, we describe quantum data encoding methods needed to implement quantum machine learning including the counterparts to traditional feature extraction and kernel embeddings methods. Third, we show how quantum algorithms naturally calculate Bayesian quantities of interest such as posterior distributions and marginal likelihoods. Our goal then is to show how quantum algorithms solve statistical machine learning problems. On the theoretical side, we provide quantum versions of high dimensional regression, Gaussian processes and stochastic gradient descent. On the empirical side, we apply a quantum FFT algorithm to Chicago house price data. Finally, we conclude with directions for future research. 相似文献
972.
多通道磁共振成像方法采用多个接收线圈同时欠采样k空间以加快成像速度,并基于后处理算法重建图像,但在较高加速因子时,其图像重建质量仍然较差.本文提出了一种基于PCAU-Net的快速多通道磁共振成像方法,将单通道实数U型卷积神经网络拓展到多通道复数卷积神经网络,设计了一种结构不对称的U型网络结构,通过在解码部分减小网络规模以降低模型的复杂度.PCAU-Net网络在跳跃连接前增加了1×1卷积,以实现跨通道信息交互.输入和输出之间利用残差连接为误差的反向传播提供捷径.实验结果表明,使用规则和随机采样模板,在不同加速因子时,相比常规的GRAPPA重建算法和SPIRiT重建方法,本文提出的PCAU-Net方法可高质量重建出磁共振复数图像,并且相比于PCU-Net方法,PCAU-Net减少了模型参数、缩短了训练时间. 相似文献
973.
针对半片光伏组件电致发光(electroluminescence,EL)缺陷自动识别过程中训练用样本不足导致模型过拟合的问题,采用深度卷积生成对抗网络(deep convolutional generative adversarial networks,DCGANs)生成可控制属性的半片光伏组件EL图像,再采用多尺度结构相似性(multiscale structural similarity,MS-SSIM)指标对生成的EL图像与拍摄的EL图像之间的相似程度进行了评估。评估结果得到,使用DCGANs生成的所有类型半片光伏组件的EL图像与拍摄的EL图像的MS-SSIM指标都大于0.55,大部分的MS-SSIM值在0.7附近。在分类模型的训练过程中,测试集准确率随着训练集中生成图像数量的增加而升高,当生成图像数量达到6 000张时,测试集准确率达到97.92%。实验结果表明,采用DCGANs能够生成高质量且可控制属性的半片光伏组件EL图像,较好地解决因缺少训练样本而导致的模型过拟合问题。 相似文献
974.
Dimuon events induced by charm-quark productions from neutrino deep inelastic scattering (DIS) processes have been studied in traditional DIS experiments for decades. The recent progress in neutrino telescopes makes it possible to search for such dimuon events at energies far beyond the laboratory scale. In this study, we construct a simulation framework to calculate yields and distributions of dimuon signals in an IceCube-like km3 scale neutrino telescope. Owing to the experimental limitation in the resolution of double-track lateral distance, only dimuons produced outside the detector volume are considered. Detailed information about simulation results for a 10-year exposure is presented. As an earlier paper[Physical Review D 105, 093005 (2022)] and ours report on a similar situation, we use that paper as a baseline to conduct comparisons. We then estimate the impacts of different calculation methods of muon energy losses. Finally, we study the experimental potential of dimuon searches under the hypothesis of single-muon background only. Our results based on a simplified double-track reconstruction indicate a moderate sensitivity, especially with the ORCA configuration. Further developments on both the reconstruction algorithm and possible detector designs are thus required and are under investigation. 相似文献
975.
组合单元法在砂井地基有限元分析中的应用 总被引:1,自引:0,他引:1
针对砂井地基的平面应变有限元分析,本文首次将组合单元法引入到砂井地基的分析中,提出砂墙组合单元。该单元对常规等参元进行改进,在单元内部同时考虑砂井的涂抹作用和井阻作用,从而克服了常规有限元法在计算砂井地基时单元数和节点数过多的缺点。将砂墙组合单元加入USAP有限元计算软件,工程算例分析结果表明:与已有的各砂井地基的平面应变解答和荷兰的基础工程有限元分析软件PLAXIS相比,解答合理并有效地考虑砂井的涂抹作用和井阻作用;与常规有限元法相比,在保证计算精度的前提下,减少了可观的单元数和节点数,降低了计算的工作量。 相似文献
976.
Despite the increase in horizontal well applications, scaling fluid displacement in porous medium with horizontal wells is
yet to be fully investigated. Determining the conditions under which horizontal wells may lead to better oil recovery is of
great importance to the petroleum industry. In this paper, a numerical sensitivity study was performed for several well configurations.
The study is performed in order to reveal the functional relationships between the scaling groups governing the displacement
and the performance of immiscible displacements in homogeneous reservoirs produced by horizontal wells. These relationships
can be used as a quick prediction tool for the fractional oil recovery for any combinations of the scaling groups, thus eliminating
the need for the expensive fine-mesh simulations. In addition, they provide the condition under which a horizontal well configuration
may yield better recovery performance. These results have potential applications in modeling immiscible displacements and
in the scaling of laboratory displacements to field conditions. 相似文献
977.
978.
The macroscopic dynamics of a kinetic equation involving a model wave-particle collision operator of plasma physics is investigated.
The Chapman-Enskog asymptotics is first considered in the framework of a hydrodynamic scaling. The obtained macroscopic model
still involves a kinetic variable, the particle energy in the rest frame of the fluid, but shares similarities with the compressible
Navier-Stokes equation of gas dynamics. Then a diffusive scaling is examined under the hypothesis of small perturbations of
a global equilibrium. In this case, the macroscopic model couples the usual incompressible Navier-Stokes with a diffusion
equation for the energy distribution function of the particles, constrained by an extended version of the Boussinesq relation.
In both cases, the effect of a Lorentz force term is developed, in the perspective of plasma physical modelling.
Received June 16, 1997 相似文献
979.
980.
Cobalt‐Catalyzed Allylation of Heterobicyclic Alkenes: Ligand‐Induced Divergent Reactivities
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Yuan Huang Chao Ma Yi Xin Lee Rui‐Zhi Huang Prof. Yu Zhao 《Angewandte Chemie (International ed. in English)》2015,54(46):13696-13700
The allylation of heterobicyclic alkenes is presented for the first time. By using an inexpensive cobalt salt as the catalyst and easy‐to‐handle potassium allyltrifluoroborate as the reagent, an unprecedented formal hydroallylation of the bicyclic alkenes is realized in high efficiency. When a chiral cobalt/bis(phosphine) complex is used instead, the alternative ring‐opening products can be obtained in high yield and excellent enantioselectivity. 相似文献