期刊文献+
共找到11,066篇文章
< 1 2 250 >
每页显示 20 50 100
关于格的凸子格格 预览
1
作者 张懿慧 吴妙玲 《内蒙古工业大学学报:自然科学版》 2019年第2期81-85,共5页
本文对格的凸子格格进行了研究,给出了凸子格的两种定义,同时证明了这两个定义的等价性,得到了凸子格格是分配格、幂集格的充分必要条件,研究了凸子格格对格的刻画问题和凸子格的数量问题.
关键词 偏序集 子格 凸子格
在线阅读 免费下载
Caution in building a Burgers circuit for studying secondary dislocations
2
作者 Wen-Sheng Xu Wen-Zheng Zhang 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第6期1192-1197,共6页
As the Burgers vector of a secondary dislocation may not conform to the translation vectors in the periodic pattern in a high-resolution transmission electron microscope(HRTEM) image, a Burgers circuit directly constr... As the Burgers vector of a secondary dislocation may not conform to the translation vectors in the periodic pattern in a high-resolution transmission electron microscope(HRTEM) image, a Burgers circuit directly constructed according to an HRTEM image may render a wrong Burgers vector. The HRTEM images of the habit plane(HP) of δ precipitate in an Inconel 718 alloy were re-examined by using different Burgers circuits, as an example. Evidence is found for predicted secondary dislocation associated with a down step. The Burgers vector of the dislocation is 1/6[112]/1/3[001]δ, determined with the Burgers circuit built on the reference of the displacement shift completely lattice(DSCL). It is consistent with both the calculated and the measured result of the major defects in the habit plane. Different Burgers vectors due to different Burgers circuits were explained quantitatively. The present study has a general implication for the determination of the Burgers vectors of secondary interfacial dislocations in other systems. 展开更多
关键词 Dislocation BURGERS vector BURGERS CIRCUIT COINCIDENCE site LATTICE (CSL) Displacement shift COMPLETELY LATTICE (DSCL) LATTICE CORRESPONDENCE
S-格上的同余关系 预览
3
作者 齐彩霞 阳城 +1 位作者 郭兰坤 刘丽 《四川师范大学学报:自然科学版》 CAS 北大核心 2019年第1期25-29,共5页
引入S-格上的同余和伪同余,并研究两者的内在联系;给出S-格上的同态定理,推广了经典格上同余的相关结论;讨论分配S-格上同余关系,并证明分配S-格上的任意二元关系H可自然诱导1个包含H的最小S-格同余.
关键词 S-格 同余 伪同余 同态 S-分配格
在线阅读 免费下载
Development of a particle swarm optimization based support vector regression model for titanium dioxide band gap characterization 预览
4
作者 Taoreed O.Owolabi 《半导体学报:英文版》 EI CAS CSCD 2019年第2期49-55,共7页
Energy band gap of titanium dioxide(TiO2) semiconductor plays significant roles in many practical applications of the semiconductor and determines its appropriateness in technological and industrial applications such ... Energy band gap of titanium dioxide(TiO2) semiconductor plays significant roles in many practical applications of the semiconductor and determines its appropriateness in technological and industrial applications such as UV absorption, pigment,photo-catalysis, pollution control systems and solar cells among others. Substitution of impurities into crystal lattice structure is the most commonly used method of tuning the band gap of TiO2 for specific application and eventually leads to lattice distortion. This work utilizes the distortion in the lattice structure to estimate the band gap of doped TiO2, for the first time, through hybridization of a particle swarm optimization algorithm(PSO) with a support vector regression(SVR) algorithm for developing a PSO-SVR model. The precision and accuracy of the developed PSO-SVR model was further justified by applying the model for estimating the effect of cobalt-sulfur co-doping, nickel-iodine co-doping, tungsten and indium doping on the band gap of TiO2 and excellent agreement with the experimentally reported values was achieved. Practical implementation of the proposed PSO-SVR model would further widen the applications of the semiconductor and reduce the experimental stress involved in band gap determination of TiO2. 展开更多
关键词 band gap LATTICE DISTORTION crystal LATTICE parameters particle SWARM optimization support vector regression titanium dioxide
在线阅读 下载PDF
Resistance Calculation of Pentagonal Lattice Structure of Resistors
5
作者 M.Q.Owaidat J.H.Asad 《理论物理通讯:英文版》 SCIE CAS CSCD 2019年第8期935-938,共4页
In this study, the effective resistance between any two lattice sites in a two-dimensional pentagonal lattice structure of identical resistors is determined by means of the lattice Green’s function method.Some numeri... In this study, the effective resistance between any two lattice sites in a two-dimensional pentagonal lattice structure of identical resistors is determined by means of the lattice Green’s function method.Some numerical results of the resistance for small separations between lattice sites are presented. 展开更多
关键词 LATTICE Green’s function pentagonal LATTICE RESISTANCE NUMERICAL RESULTS
并行LLL算法研究综述 预览
6
作者 刘洋 陈经纬 +1 位作者 冯勇 吴文渊 《计算机工程与应用》 CSCD 北大核心 2019年第16期36-41,共6页
Lenstra-Lenstra-Lovasz(LLL)格基约化算法自1982年被提出以来,已被成功应用于计算机代数、编码理论、密码分析、算法数论、整数规划等众多领域。经过三十多年的发展,串行LLL算法的理论分析和实际效率都已得到显著改进,但仍不能满足密... Lenstra-Lenstra-Lovasz(LLL)格基约化算法自1982年被提出以来,已被成功应用于计算机代数、编码理论、密码分析、算法数论、整数规划等众多领域。经过三十多年的发展,串行LLL算法的理论分析和实际效率都已得到显著改进,但仍不能满足密码分析等领域处理较大规模问题的需要。因此,并行LLL算法研究被寄予厚望。对并行LLL算法的研究现状进行了综述,总结了当前并行LLL算法设计与分析中存在的问题和难点,并对其未来发展趋势进行了展望。 展开更多
关键词 格基约化 LLL算法 并行计算
在线阅读 下载PDF
NTRU密码算法的安全性分析 预览
7
作者 李超 杨智超 《河南师范大学学报:自然科学版》 CAS 北大核心 2019年第1期17-25,共9页
随着量子计算的快速发展,目前主流的公钥密码体制如RSA、ECC等均已找到多项式时间复杂度的量子求解算法.NTRU密码算法由于至今未找到有效的量子求解算法,被认为具有抗量子计算攻击的能力,加之其具有加解密速度快、内存需求小等特点,已... 随着量子计算的快速发展,目前主流的公钥密码体制如RSA、ECC等均已找到多项式时间复杂度的量子求解算法.NTRU密码算法由于至今未找到有效的量子求解算法,被认为具有抗量子计算攻击的能力,加之其具有加解密速度快、内存需求小等特点,已经在公钥密码领域受到了广泛关注.首先介绍NTRU密码算法的加解密流程以及算法的改进方案,然后从格攻击和非格攻击两方面分析NTRU密码算法的安全性,重点介绍格攻击在子域上的最新进展,以及解密错误攻击的提出和改进. 展开更多
关键词 NTRU 密码分析 格算法
在线阅读 免费下载
A coupled-channel lattice study of the resonance-like structure Zc(3900)
8
作者 陈婷 陈莹 +7 位作者 宫明 刘川 刘柳明 刘玉斌 刘朝峰 马建平 Markus Werner 张剑波 《中国物理C:英文版》 SCIE CAS CSCD 2019年第10期24-37,共14页
In this exploratory study, near-threshold scattering of D and D^-* meson is investigated using lattice QCD with Nf=2+1+1 twisted mass fermion configurations. The calculation is performed in the coupled-channel Lü... In this exploratory study, near-threshold scattering of D and D^-* meson is investigated using lattice QCD with Nf=2+1+1 twisted mass fermion configurations. The calculation is performed in the coupled-channel Lüscher finite-size formalism. The study focuses on the channel with I^G(J^PC)=1^+(1+^+-) where the resonance-like structure Zc(3900) was discovered. We first identify the two most relevant channels and the lattice study is performed in the two-channel scattering model. Combined with the two-channel Ross-Shaw theory, scattering parameters are extracted from the energy levels by solving the generalized eigenvalue problem. Our results for the scattering length parameters suggest that for the particular lattice parameters that we studied, the best fit parameters do not correspond to the peak in the elastic scattering cross-section near the threshold. Furthermore, in the zero-range Ross-Shaw theory, the scenario of a narrow resonance close to the threshold is disfavored beyond the 3σ level. 展开更多
关键词 Luescher FORMALISM LATTICE QCD computation EXOTIC MESONS
基于手机蓝牙与FPGA的多功能琴键设计 预览
9
作者 覃琴 《电子世界》 2019年第10期145-146,共2页
在大众生活环境和质量普遍改善、业余文化生活需求不断提升的情况下,人们对电子琴系统设计的要求也越来越高。本文介绍了一种手机蓝牙与FPGA的多功能琴键设计方法,可实现手机蓝牙触屏控制弹奏的暂停与启动,也可通过蓝牙模块传输音乐到... 在大众生活环境和质量普遍改善、业余文化生活需求不断提升的情况下,人们对电子琴系统设计的要求也越来越高。本文介绍了一种手机蓝牙与FPGA的多功能琴键设计方法,可实现手机蓝牙触屏控制弹奏的暂停与启动,也可通过蓝牙模块传输音乐到手机存储、回放。蓝牙模块HC-05负责接收无线数据并交由FPGA处理。用户通过操作安卓APP界面按钮实现对Lattice可编程FPGA多功能琴键进行无线控制。设计具有一定的实用价值。 展开更多
关键词 蓝牙模块 FPGA 多功能 设计 手机 琴键 LATTICE 无线控制
在线阅读 下载PDF
Dynamical properties of ultracold Bose atomic gases in one-dimensional optical lattices created by two schemes
10
作者 朱江 边成玲 王红晨 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第9期175-179,共5页
An optical lattice could be produced either by splitting an input light(splitting scheme) or by reflecting the input light by a mirror(retro-reflected scheme).We study quantum dynamical properties of an atomic Bose-Ei... An optical lattice could be produced either by splitting an input light(splitting scheme) or by reflecting the input light by a mirror(retro-reflected scheme).We study quantum dynamical properties of an atomic Bose-Einstein condensate(BEC) in the two schemes.Adopting a mean field theory and neglecting collision interactions between atoms, we find that the momentum and spatial distributions of BEC are always symmetric in the splitting scheme which, however, are asymmetric in the retro-reflected scheme.The reason for this difference is due to the local field effect.Furthermore, we propose an effective method to avoid asymmetric diffraction. 展开更多
关键词 optical lattice BOSE-EINSTEIN CONDENSATE local field effect
Lattice Boltzmann method for simulating flows in open-channel with partial emergent rigid vegetation cover 预览
11
作者 Zhong-hua Yang Feng-peng Bai +1 位作者 Wen-xin Huai Cheng-guang Li 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第4期717-724,共8页
Flows in open-channel with partial emergent rigid vegetation cover are simulated using the lattice Boltzmann method (LBM) described by the 2-D nonlinear shallow water equations. The effect of vegetation is represented... Flows in open-channel with partial emergent rigid vegetation cover are simulated using the lattice Boltzmann method (LBM) described by the 2-D nonlinear shallow water equations. The effect of vegetation is represented with the vegetation roughness coefficient, which is related to the vegetation density, diameter of the vegetation elements and drag coefficient. The model is verified by three numerical tests: flow in a 180° curved open channel with partial vegetation cover at the outer bank, flow in a rectangular channel with a finite patch of vegetation and flow in a rectangular channel with a vegetated bank. Numerical results are compared with the experimental data, and the good agreement proved that the presented model can model the vegetated channel flows correctly. 展开更多
关键词 Open-channel flow RIGID VEGETATION lattice BOLTZMANN method (LBM) shallow water equations VEGETATION ROUGHNESS coefficient
在线阅读 下载PDF
Lattice-Based Double-Authentication-Preventing Ring Signature for Security and Privacy in Vehicular Ad-Hoc Networks
12
作者 Jinhui Liu Yong Yu +4 位作者 Jianwei Jia Shijia Wang Peiru Fan Houzhen Wang Huanguo Zhang 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第5期575-584,共10页
Amidst the rapid development of the Internet of Things (loT), Vehicular Ad-Hoc NETwork (VANET), a typical loT application, are bringing an ever-larger number of intelligent and convenient services to the daily lives o... Amidst the rapid development of the Internet of Things (loT), Vehicular Ad-Hoc NETwork (VANET), a typical loT application, are bringing an ever-larger number of intelligent and convenient services to the daily lives of individuals. However, there remain challenges for VANETs in preserving privacy and security. In this paper, we propose the first lattice-based Double-Authentication-Preventing Ring Signature (DAPRS) and adopt it to propose a novel privacy-preserving authentication scheme for VANETs, offering the potential for security against quantum computers. The new construction is proven secure against chosen message attacks. Our scheme is more efficient than other ring signature in terms of the time cost of the message signing phase and verification phase, and also in terms of signature length. Analyses of security and efficiency demonstrate that our proposed scheme is provably secure and efficient in the application. 展开更多
关键词 Vehicular AD-HOC NETwork(VANET) PRIVACY security Double-Authentication-Preventing Ring Signature(DAPRS) LATTICE
Mott transition in ruby lattice Hubbard model
13
作者 保安 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期256-262,共7页
Mott transition in a ruby lattice with fermions described by the Hubbard model including on-site repulsive interaction is investigated by combining the cellular dynamical mean-field theory and the continuous-time quan... Mott transition in a ruby lattice with fermions described by the Hubbard model including on-site repulsive interaction is investigated by combining the cellular dynamical mean-field theory and the continuous-time quantum Monte Carlo algorithm.The effect of temperature and on-site repulsive interaction on the metallic–insulating phase transition in ruby lattice with fermions is discussed based on the density of states and double occupancy.In addition,the magnetic property of each phase is discussed by defining certain magnetic order parameters.Our results show that the antiferromagnetic metal is found at the low temperature and weak interaction region and the antiferromagnetic insulating phase is found at the low temperature and strong interaction region.The paramagnetic metal appears in whole on-site repulsive interaction region when the temperature is higher than a certain value and the paramagnetic insulator appears at the middle scale of temperature and on-site repulsive interaction. 展开更多
关键词 MOTT transition RUBY LATTICE HUBBARD model cellular dynamical MEAN-FIELD theory
格的模糊子集的模糊理想度 预览
14
作者 朱翔 廖祖华 《郑州大学学报:理学版》 CAS 北大核心 2019年第2期107-112,共6页
利用蕴涵运算给出了模糊理想度的新概念,它能够刻画格上的一个模糊子集满足模糊理想条件的程度.通过研究模糊理想度的性质以及与水平集的关系,给出了模糊理想度的几种等价刻画.最后讨论了模糊子集簇交的模糊理想度、模糊直积的模糊理想... 利用蕴涵运算给出了模糊理想度的新概念,它能够刻画格上的一个模糊子集满足模糊理想条件的程度.通过研究模糊理想度的性质以及与水平集的关系,给出了模糊理想度的几种等价刻画.最后讨论了模糊子集簇交的模糊理想度、模糊直积的模糊理想度,以及一个模糊子集在同态映射下像与原像的模糊理想度. 展开更多
关键词 蕴涵 同态 模糊理想
在线阅读 免费下载
Boundary scheme for lattice Boltzmann modeling of micro-scale gas flow in organic-rich pores considering surface diffusion
15
作者 左鸿 邓守春 李海波 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第3期84-96,共13页
We propose a boundary scheme for addressing multi-mechanism flow in a porous medium in slip and early transition flow regimes, which is frequently encountered in shale gas reservoirs. Micro-gaseous flow in organic-ric... We propose a boundary scheme for addressing multi-mechanism flow in a porous medium in slip and early transition flow regimes, which is frequently encountered in shale gas reservoirs. Micro-gaseous flow in organic-rich shale involves a complex flow mechanism. A self-developed boundary scheme that combines the non-equilibrium extrapolation scheme and the combined diffusive reflection and bounce-back scheme(half-way DBB) to embed the Langmuir slip boundary into the single-relaxation-time lattice Boltzmann method(SRT-LBM) enables us to describe this process, namely, the coupling effect of micro-gaseous flow and surface diffusion in organic-rich nanoscale pores. The present LBM model comes with the careful consideration of the local Knudsen number, local pressure gradient, viscosity correction model, and regularization procedure to account for the rarefied gas flows in irregular pores. Its validity and accuracy are verified by several benchmarking cases, and the calculated results by this boundary scheme accord well with our analytical solutions.This boundary scheme shows a higher accuracy than the existing studies. Additionally, a subiteration strategy is presented to tackle the coupled micro-gaseous flow and surface diffusion, which necessitates the iteration process matching of these two mechanisms. The multi-mechanism flow in the self-developed irregular pores is also numerically investigated and analyzed over a wide range of parameters. The results indicate that the present model can effectively capture the coupling effect of micro-gaseous flow and surface diffusion in a tree-like porous medium. 展开更多
关键词 lattice BOLTZMANN method(LBM) surface diffusion Langmuir slip model BOUNDARY SCHEME
Evaluating the topological charge density with the symmetricmulti-probing method
16
作者 熊光仪 张剑波 邹优豪 《中国物理C:英文版》 SCIE CAS CSCD 2019年第3期29-36,共8页
We evaluate the topological charge density of SU(3) gauge fields on a lattice by calculating the trace of the overlap Dirac matrix employing the symmetric multi-probing(SMP) method in 3 modes. Since the topological ch... We evaluate the topological charge density of SU(3) gauge fields on a lattice by calculating the trace of the overlap Dirac matrix employing the symmetric multi-probing(SMP) method in 3 modes. Since the topological charge Q for a given lattice configuration must be an integer number, it is easy to estimate the systematic error(the deviation of Q to the nearest integer). The results demonstrate a high efficiency and accuracy in calculating the trace of the inverse of a large sparse matrix with locality by using the SMP sources when compared to using point sources.We also show the correlation between the errors and probing scheme parameter rmin, as well as lattice volume NL and lattice spacing a. It is found that the computational time for calculating the trace by employing the SMP sources is less dependent on NL than by using point sources. Therefore, the SMP method is very suitable for calculations on large lattices. 展开更多
关键词 lattice QCD TOPOLOGICAL charge PROBING METHOD large SPARSE matrix INVERSE trace
模型论方法在格中的应用 预览
17
作者 陆煜杰 陈国龙 《佳木斯大学学报:自然科学版》 CAS 2019年第1期159-160,共2页
模型论方法在抽象代数,数论,拓扑学,概率论等领域有着重要的应用.运用模型论中的紧致性定理和完全理论对格中的相关性质进行研究,证明满足一定条件下的格是子格,完备∧-半格和完备格。
关键词 模型论 紧致性定理 完全理论
在线阅读 下载PDF
Interface structure prediction via CALYPSO method
18
作者 Bo Gao Pengyue Gao +3 位作者 Shaohua Lu Jian Lv Yanchao Wang Yanming Ma 《科学通报:英文版》 SCIE EI CSCD 2019年第5期301-309,共9页
The atomistic structures of solid–solid interfaces are of fundamental interests for understanding physical properties of interfacial materials.However,determination of interface structures faces a substantial challen... The atomistic structures of solid–solid interfaces are of fundamental interests for understanding physical properties of interfacial materials.However,determination of interface structures faces a substantial challenge,both experimentally and theoretically.Here,we propose an efficient method for predicting interface structures via the generalization of our in-house developed CALYPSO method for structure prediction.We devised a lattice match toolkit that allows us to automatically search for the optimal latticematched superlattice for construction of the interface structures.In addition,bonding constraints(e.g.,constraints on interatomic distances and coordination numbers of atoms)are imposed to generate better starting interface structures by taking advantages of the known bonding environment derived from the stable bulk phases.The interface structures evolve by following interfacially confined swarm intelligence algorithm,which is known to be efficient for exploration of potential energy surface.The method was validated by correctly predicting a number of known interface structures with only given information of two parent solids.The application of the developed method leads to prediction of two unknown grain boundary(GB)structures(r-GB and p-GB)of rutile TiO2∑5(2 1 0)under an O reducing atmosphere that contained Ti^3+as the result of O defects.Further calculations revealed that the intrinsic band gap of p-GB is reduced to 0.7 eV owing to substantial broadening of the Ti-3 d interfacial levels from Ti3+centers.Our results demonstrated that introduction of grain boundaries is an effective strategy to engineer the electronic properties and thus enhance the visible-light photoactivity of TiO2. 展开更多
关键词 Solid-solid interface Structure PREDICTION METHOD LATTICE MISMATCH TiO2 GRAIN boundary
Design and simulation of an innovative cylinder fabricated by selective laser melting
19
作者 Guang MENG Bin JI +3 位作者 Han HAN Chengzhang GU Renbang LIN Fujun PENG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第1期133-142,共10页
Additive Manufacturing(AM) processing has attracted wide attention due to its advantages, e.g., rapid prototyping and free design. In aeronautic and astronautic engineering, it is especially attractive to apply AM pro... Additive Manufacturing(AM) processing has attracted wide attention due to its advantages, e.g., rapid prototyping and free design. In aeronautic and astronautic engineering, it is especially attractive to apply AM processing, especially Selective Laser Melting(SLM), into primary structures that always occupy most of the whole mass of aircraft or spacecraft. In this paper, an innovative lattice sandwich structure that is suitable to be manufactured with SLM is adopted to design the typical cylinder under axial compression. Firstly, the mechanical properties of pyramidal lattice are investigated, and the bearing capacity of the lattice sandwich cylinder is given analytically for each failure mode. Secondly, a composite cylinder is re-designed in the form of lattice sandwich structure, which sizes are ultimately obtained through optimization. Finally, finite element model of the innovative cylinder is established and several kinds of imperfection are introduced to simulate the defects caused by SLM. Numerical result shows that the lattice sandwich design can obviously enhance the bearing capacity of cylindrical shell even though the original one is designed with composite material. In other words, SLM has great potential in improving the primary structure of spacecraft in the future. 展开更多
关键词 AXIAL compression CYLINDER Failure IMPERFECTION LATTICE SANDWICH structure Selective laser MELTING
Periodically modulated interaction effect on transport of Bose–Einstein condensates in lattice with local defects
20
作者 朱坤强 鱼自发 +3 位作者 高吉明 张爱霞 徐红萍 薛具奎 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第1期245-250,共6页
We theoretically investigate the periodically modulated interaction effect on the propagation properties of a traveling plane wave in a Bose–Einstein condensate(BEC) trapped in a deep annular lattice with local defec... We theoretically investigate the periodically modulated interaction effect on the propagation properties of a traveling plane wave in a Bose–Einstein condensate(BEC) trapped in a deep annular lattice with local defects both analytically and numerically. By using the two-mode ansatz and the tight-binding approximation, a critical condition for the system preserving the superfluidity is obtained analytically and confirmed numerically. We find that the coupled effects of periodic modulated atomic interactions, the quasi-momentum of the plane wave, and the defect can control the superfluidity of the system. Particularly, when we consider the periodic modulation in the system with single defect, the critical condition for the system entering the superfluid regime depends on both the defect and the momentum of the plane wave. This is different from the case for the system without the periodic modulation, where the critical condition is only determined by the defect. The modulation and quasi-momentum of the plane wave can enhance the system entering the superfluid regime. Interestingly, when the modulated amplitude/frequency, the defect strength, and the quasi-momentum of the plane wave satisfy a certain condition, the system will always be in the superfluid region. This engineering provides a possible means for studying the periodic modulation effect on propagation properties and the corresponding dynamics of BECs in disordered optical lattices. 展开更多
关键词 Bose–Einstein CONDENSATE periodic modulation SUPERFLUIDITY LATTICE with defects
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈