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关键词： 量子计算机   加密技术   超级计算机   量子密码   物理定律   微观世界   量子力学   超高性能  

摘要： 无法窃听!全面解读终极安全加密技术!近几年,基于原子和电子等微观世界的物理定律--“量子力学”的原理,而衍生出的量子计算机和量子密码等新技术备受关注。量子密码被誉为“即使使用能在未来开发出的、具有超高性能的超级计算机和量子计算机也绝对无法破解的终极安全加密技术”。

关键词： 团簇Mo_(3)S_(4)   密度泛函理论   极化率   催化  

摘要： 为了探究微观状态下,团簇Mo_(3)S_(4)内部电子的变化情况及其催化机理,基于密度泛函理论的B3LYP方法对团簇Mo_(3)S_(4)的几何构型进行优化和频率计算,得到一、三重态各4种优化构型。文中计算并讨论了该团簇的极化率、能隙差以及Mo、S原子和各原子间的电子自旋密度,研究结果表明:构型1(3)的极化率各向异性不变量最小,说明构型1(3)对于外场的响应最弱,受外场影响的难度更大。当受外场作用时重态构型的电子云发生形变程度小于除构型2(1)以外的一重态构型,其中构型2(1)的极化率最小,原子间的相互作用力最强,结构最紧凑且最不易发生变形。比较三重态构型的电子自旋密度发现,构型1(3)的外围电子自旋密度分布均匀,内部原子间成键强度相近,其构型稳定性优于其他三重态构型。在催化反应中,构型4(1)的能隙差最小,化学反应能力最大,催化活性最好。

关键词： Algebra   Integral transforms   Optical, image and video signal processing   Image recognition   Image sensors   Integral transforms   Computer vision and image processing techniques   Video signal processing   Data handling techniques   Spatial and pictorial databases  

摘要： Face detection is playing a pivotal role for crowd counting and abnormal events detection. However, it is vulnerable to face presentation attacks by printed photos, videos, and 3D masks of real human faces. Although numerous detection techniques based on deep learning have been employed to address the problem of face presentation attacks, there are still several weaknesses in these approaches, such as high algorithm complexity and a lack of detection ability. To overcome these weaknesses, a method based on a multilevel fusion network with Laplacian embedding (MFNet-LE) for the detection of face presentation attacks is proposed. First, a shallow network that contains just three layers was developed, which makes the model faster. Then, an optimised multilevel fusion strategy was developed to combine the input with the output of all previous layers to improve the detection ability of the method. Finally, a Laplacian embedding algorithm is introduced to maintain the inter-class discrimination and penalise the intra-class distance. Under the joint supervision of Laplacian loss and softmax loss, the proposed approach can obtain more discriminative features, which enhance the accuracy of attack detection. Experiments were conducted with three public databases for face presentation attacks: CASIA FASD, Idiap Replay Attack database and MSU USSA. The results demonstrate that the MFNet-LE model can outperform the state-of-the-art methods.

关键词： 量子力学  

ISBN: (纸本)9787520393966

摘要： “量子逻辑”作为“来源于量子力学的逻辑”或“为量子力学提供解释的逻辑”是一个多元化的体系。众多量子逻辑系统与经典逻辑一样，都是人们对非形式化推理以特定的方式进行抽象（形式化）而得到的。这些量子逻辑系统的存在为逻辑多元主义提供了充分的实例，特别是使（某种）三值逻辑、次协调逻辑等原本独立于量子力学而存在的非经典逻辑与量子力学的解释问题联系起来，进而使它们也像经典逻辑一样有了描述或解释现实世界的能力，而不仅仅是数学游戏。传统的逻辑多元主义者通常不重视量子力学和量子逻辑，其结果就是即便他们成功地论证了逻辑多元主义，非经典逻辑对于很多人仍然是可有可无的。但在量子力学解释问题中情况发生了翻天覆地的变化：在经典逻辑框架内做出的解释甚至有可能比非经典逻辑更难接受，于是“修改逻辑”这一选项就变得自然多了。可以说，量子力学解释问题为非经典逻辑提供了崭新的应用场景，为逻辑多元主义找到了更有力的论证思路。

关键词： quantum dynamics   MCTDH   diffusion maps  

摘要： Grid-based schemes for simulating quantum dynamics, such as the multi-configuration time-dependent Hartree (MCTDH) method, provide highly accurate predictions of the coupled nuclear and electronic dynamics in molecular systems. Such approaches provide a multi-dimensional, time-dependent view of the system wavefunction represented on a coordinate grid;in the case of non-adiabatic simulations, additional information about the state populations adds a further layer of complexity. As such, wavepacket motion on potential energy surfaces which couple many nuclear and electronic degrees-of-freedom can be extremely challenging to analyse in order to extract physical insight beyond the usual expectation-value picture. Here, we show that non-linear dimensionality reduction (NLDR) methods, notably diffusion maps, can be adapted to extract information from grid-based wavefunction dynamics simulations, providing insight into key nuclear motions which explain the observed dynamics. This approach is demonstrated for 2-D and 9-D models of proton transfer in salicylaldimine, as well as 8-D and full 12-D simulations of cis-trans isomerization in ethene;these simulations demonstrate how NLDR can provide alternative views of wavefunction dynamics, and also highlight future developments.

关键词： Production data analysis   Production forecasting   Deconvolution   Echo-state networks   Machine learning  

摘要： Production data analysis for low permeability shale reservoirs is crucial in characterizing flow regimes and reservoir properties, and the forecasting of production is essential for portfolio and reservoir management. However, traditional methods have failed due to incorrect physics or complicated convolution from the well control history. In this research, we provide a physics-assisted analytics workflow using Laplacian Eigenmaps Coupled Echo-State Network (LEESN) to facilitate and accelerate the analysis of noisy historical production data. Pressure-rate deconvolution is an ill-posed, complex time-series problem. When using the traditional EchoState Network (ESN), the number of training sets is less than the number of neurons. To solve this problem, we apply LEESN to first deconvolve noisy variable-pressure variable-rate histories into smooth constant-pressure rate responses. The physics-based training features and training algorithm provide additional benefits in addition to the analytic approach by honoring transient flow physics. After training, the constant-pressure rate response can be predicted and used for reservoir characterization, and the trained model could be further used for production and EUR forecasting through long-term rate predictions to the economic limit. The proposed workflow was first validated by synthetic cases where the production data were obtained through simulation. The short-term flow rate history was obtained by specifying highly variable controlling pressures. We also added artificial white Gaussian noise to mimic measured signals collected in the field and input this information into LEESN for deconvolution. The constant-pressure rate response was generated after training to determine flow regimes and properties such as permeability using a traditional transient testing specialized plot. All outcomes from the analytics approach were validated by comparison against the input data of the synthetic simulation model. The advantages of t

关键词： Discrete Wigner distribution function   Open quantum dynamics theory   Quantum Fokker-Planck equation   Hierarchical equations of motion  

摘要： Discretizing a distribution function in a phase space for an efficient quantum dynamics simulation is a non-trivial challenge, in particular for a case in which a system is further coupled to environmental degrees of freedom. Such open quantum dynamics is described by a reduced equation of motion (REOM), most notably by a quantum Fokker-Planck equation (QFPE) for a Wigner distribution function (WDF). To develop a discretization scheme that is stable for numerical simulations from the REOM approach, we employ a two-dimensional (2D) periodically invariant system-bath (PISB) model with two heat baths. This model is an ideal platform not only for a periodic system but also for a non-periodic system confined by a potential. We then derive the numerically "exact" hierarchical equations of motion (HEOM) for a discrete WDF in terms of periodically invariant operators in both coordinate and momentum spaces. The obtained equations can treat non-Markovian heat-bath in a non-perturbative manner at finite temperatures regardless of the mesh size. As demonstrations, we numerically integrate the discrete QFPE for a 2D free rotor and harmonic potential systems in a high-temperature Markovian case using a coarse mesh with initial conditions that involve singularity.

关键词： 哲学思想  

ISBN: (纸本)9787553524481

摘要： 本书是德国哲学家叔本华的哲学著作，主要从世界作为表象及世界作为意志这两大方面来阐述其哲学思想。

关键词： Laplacian matrix   Mixed graph   Skewed converse   Spectral radius   Weighted directed graph  

摘要： The notion of skewed converse of a weighted directed graph is introduced in this article. Several characterizations of singularity of the skewed converse of the weighted directed graphs are provided here. This article provides some upper bounds and lower bounds on the Laplacian spectral radius of weighted directed graphs. Characterizations of the weighted directed graphs that achieve these bounds are also supplied here.

关键词： Quantum-classical   Hybrid bracket   Quantum backreaction  

摘要： Using the example of the harmonic oscillator, we illustrate the use of hybrid dynamical brackets in analyzing quantum-classical interaction. We only assume that a hybrid dynamical bracket exists, is bilinear, and reduces to the pure quantum or classical bracket when acting on pure quantum or classical variables. Any hybrid bracket obeying these natural requirements will produce the same dynamics for pure classical or quantum variables, given a hybrid Hamiltonian. Backreaction is manifested in the evolution of a nonvanishing commutator between classical variables. The more massive the classical system is, the less it is affected by backreaction. Interestingly, we show that while pure variables evolve to violate the pure canonical relations, they always obey the hybrid canonical relations. The dynamics of hybrid variables, on the other hand, is shown to require a fully specified and consistent hybrid bracket, otherwise evolution cannot be defined.