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文章速递A Mathematical Comparison of the Schwarzschild and Kerr Metrics 认领
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作者 J.-F. Pommaret 《现代物理(英文)》 2020年第10期1672-1710,共39页
A few physicists have recently constructed the generating compatibility conditions (CC) of the Killing operator for the Minkowski (M), Schwarzschild (S) and Kerr (K) metrics. They discovered second order CC, well know... A few physicists have recently constructed the generating compatibility conditions (CC) of the Killing operator for the Minkowski (M), Schwarzschild (S) and Kerr (K) metrics. They discovered second order CC, well known for M, but also third order CC for S and K. In a recent paper (DOI:10.4236/jmp.2018.910125) we have studied the cases of M and S, without using specific technical tools such as Teukolski scalars or Killing-Yano tensors. However, even if S(<em>m</em>) and K(<em>m</em>, <em>a</em>) are depending on constant parameters in such a way that S <span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">&rarr;</span></span></span></span> M when <em>m</em> <span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">&rarr;</span></span></span></span> 0 and K<span style="white-space:nowrap;"><span style="white-space:nowrap;">&rarr;</span></span><span style="white-space:nowrap;"><span style="white-space:nowrap;"></span></span> S when <em>a</em> <span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">&rarr;</span></span></span></span> 0, the CC of S do not provide the CC of M when <em>m</em> <span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">&rarr;</span></span></span> 0 while the CC of K do not provide the CC of S when a <span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">&rarr;</span></span></span> 0. In this paper, using tricky motivating examples of operators with constant or variable parameters, we explain why the CC are depending on the choice of the parameters. In particular, the only purely intrinsic objects that can be defined, namely the extension modules, may change drastically. As the algebroid bracket is compatible with the <em>prolongation/projection</em> (PP) procedure, we provide for the first time all the CC for K in an intrinsic way, showing that they only depend on the underlying Killing algebra and that the role played by the Spencer operator is crucial. We get K < S < M with 2 < 4 < 10 for the Killing algebras and explain why the formal search of the CC for M, S or K are strikingly different, even if each Spencer sequence is isomorphic to the tensor product of the Poincaré sequence for the exterior derivative by the corresponding Lie algebra. 展开更多
关键词 Formal Integrability Involutivity Compatibility Condition Janet Sequence Spencer Sequence Minkowski Metric Schwarzschild Metric Kerr Metric
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深度学习方法在上海市PM2.5浓度预报中的应用 认领
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作者 马井会 曹钰 +2 位作者 余钟奇 瞿元昊 许建明 《中国环境科学》 EI CAS CSCD 北大核心 2020年第2期530-538,共9页
为提升PM2.5浓度预报能力,尤其是对PM2.5重污染的预报能力,以中尺度气象-化学耦合模式系统(WRF-Chem)为基础,结合中尺度WRF气象预报数据、地面及高空气象观测数据、PM2.5浓度观测数据,基于人工智能深度学习序列到序列的算法建立了上海市... 为提升PM2.5浓度预报能力,尤其是对PM2.5重污染的预报能力,以中尺度气象-化学耦合模式系统(WRF-Chem)为基础,结合中尺度WRF气象预报数据、地面及高空气象观测数据、PM2.5浓度观测数据,基于人工智能深度学习序列到序列的算法建立了上海市PM2.5统计预报模型.结果表明,人工智能深度学习算法(Seq2seq)明显修正了WRF-Chem模式由于模型非客观性造成的偏差,提高了上海市PM2.5浓度的预报能力;该算法优化和修正了WRF-Chem模式结果,并通过检验发现可以使PM2.5浓度预报值与实况值间的相关系数由0.51上升至0.79,均方根误差由25.9μg/m3下降至15.01μg/m3.而单独使用套索法(Lasso)线性回归算法对WRF-Chem模式优化效果不理想.基于Seq2seq的PM2.5浓度预报修正模型能够有效提升预报精度. 展开更多
关键词 SEQUENCE to sequence模型 PM2.5浓度预报 WRF-Chem 上海市
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Log-behavior of Two Sequences Related to the Elliptic Integrals 认领
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作者 Brian Yi SUN James Jing-Yu ZHAO 《应用数学学报:英文版》 SCIE CSCD 2020年第3期590-602,共13页
Two interesting sequences arose in the study of the series expansions of the complete elliptic integrals,which are called the Catalan-Larcombe-French sequence{Pn}n≥0 and the Fennessey-Larcombe-French sequence{Vn}n≥0... Two interesting sequences arose in the study of the series expansions of the complete elliptic integrals,which are called the Catalan-Larcombe-French sequence{Pn}n≥0 and the Fennessey-Larcombe-French sequence{Vn}n≥0 respectively.In this paper,we first establish some criteria for determining log-behavior of a sequence based on its three-term recurrence.Then we prove the log-convexity of{Vn~2-V(n-1)V(n+1)}n≥2 and{n!Vn}n≥1,the ratio log-concavity of{Pn}n≥0 and the sequence{An}n≥0 of Apéry numbers,and the ratio log-convexity of{Vn}n≥1. 展开更多
关键词 the Catalan-Larcombe-French sequence the Fennessey-Larcombe-French sequence Apéry numbers LOG-CONCAVE log-convex three-term recurrence
Phase Transitions Governed by the Fifth Power of the Golden Mean and Beyond 认领
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作者 Hans Hermann Otto 《凝固态物理国际期刊(英文)》 2020年第3期135-158,共24页
In this contribution results from different disciplines of science were compared to show their intimate interweaving with each other having in common the golden ratio <i><span style="font-family:Verdana;... In this contribution results from different disciplines of science were compared to show their intimate interweaving with each other having in common the golden ratio <i><span style="font-family:Verdana;">φ</span></i><span style="font-family:Verdana;"> respectively its fifth power </span><i><span style="font-family:Verdana;">φ</span></i><sup><span style="font-family:Verdana;">5</span></sup><span style="font-family:Verdana;">. The research fields cover model calculations of statistical physics associated with phase transitions, the quantum probability of two particles, new physics of everything suggested by the information relativity theory (</span><i><span style="font-family:Verdana;">IRT</span></i><span style="font-family:Verdana;">) including explanations of cosmological relevance, the </span><i><span style="font-family:Verdana;">ε</span></i><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">infinity theory, superconductivity, and the </span><i><span style="font-family:Verdana;">Tammes</span></i><span style="font-family:Verdana;"> problem of the largest diameter of </span><i><span style="font-family:Verdana;">N</span></i><span style="font-family:Verdana;"> non-overlapping circles on the surface of a sphere with its connection to viral morphology and crystallography. Finally, </span><i><span style="font-family:Verdana;">Fibo</span><span style="font-family:Verdana;">nacci</span></i><span style="font-family:Verdana;"> anyons proposed for topological quantum</span><span style="font-family:Verdana;"> computation (</span><i><span style="font-family:Verdana;">TQC</span></i><span style="font-family:Verdana;">) were briefly described in comparison to the recently formulated reverse </span><i><span style="font-family:Verdana;">Fibonacci</span></i><span style="font-family:Verdana;"> approach using the </span><span style="font-family:Verdana;"><em>Jani</em></span></s 展开更多
关键词 Golden Mean Phase Transitions Hard-Hexagon Respectively Hard-Square Gas Model Quantum Probability Information Relativity Theory (IRT) ε-Infinity Theory Superconductivity Tammes Problem Viral Morphology Helical Microtubules Janičko Number Sequence Topological Quantum Computation Fibonacci Lattice CRYSTALLOGRAPHY
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Image Encryption and Decryption Based on Chaotic Algorithm 认领
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作者 Ruyue Tian 《应用数学与应用物理(英文)》 2020年第9期1814-1825,共12页
This paper analyzes the problems in image encryption and decryption based on chaos theory. This article introduces the application of the two-stage Logistic algorithm in image encryption and decryption, then by inform... This paper analyzes the problems in image encryption and decryption based on chaos theory. This article introduces the application of the two-stage Logistic algorithm in image encryption and decryption, then by information entropy analysis it is concluded that the security of this algorithm is higher compared with the original image;And a new image encryption and decryption algorithm based on the combination of two-stage Logistic mapping and <i>M</i> sequence is proposed. This new algorithm is very sensitive to keys;the key space is large and its security is higher than two-stage Logistic mapping of image encryption and decryption technology. 展开更多
关键词 Chaos Algorithm Image Encryption and Decryption Two-Stage Logistic Mapping M Sequence
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Modified Atomic Orbital Calculations of Energy of the (2<i>s</i><sup>2</sup><sup>1</sup><i>S</i>) Ground-State, the (2<i>p</i><sup>2</sup><sup>1</sup><i>D</i>);(3<i>d</i><sup>2</sup><sup>1</sup><i>D</i>) and (4<i>f</i><sup>2</sup><sup>1</sup><i>I</i>) Doubly Excited States of Helium Isoelectronic Sequence from H<sup>-</sup>to Ca<sup>18+</sup> 认领
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作者 Malick Sow Ibrahima Sakho +9 位作者 Boubacar Sow Abdou Diouf Youssou Gning Babou Diop Matabara Dieng Abdourahmane Diallo Mamadou Diouldé Ba Jean Kouhissoré Badiane Mamadi Biaye Ahmadou Wagué 《应用数学与应用物理(英文)》 2020年第1期85-99,共15页
We report in this paper the ground-state energy 2s2 1S and total energies of doubly excited states 2p2 1D, 3d2 1D, 4f2 1I of the Helium isoelectronic sequence from H- to Ca18+. Calculations are performed using the Mod... We report in this paper the ground-state energy 2s2 1S and total energies of doubly excited states 2p2 1D, 3d2 1D, 4f2 1I of the Helium isoelectronic sequence from H- to Ca18+. Calculations are performed using the Modified Atomic Orbital Theory (MAOT) in the framework of a variational procedure. The purpose of this study required a mathematical development of the Hamiltonian applied to Slater-type wave function [1] combining with Hylleraas-type wave function [2]. The study leads to analytical expressions which are carried out under special MAXIMA computational program. This first proposed MAOT variational procedure, leads to accurate results in good agreement as well as with available other theoretical results than experimental data. In the present work, a new correlated wave function is presented to express analytically the total energies for the 2s2 1S ground state and each doubly 2p2 1D, 3d2 1D, 4f2 1I excited states in the He-like systems.The present accurate data may be a useful guideline for future experimental and theoretical studies in the (nl2) systems. 展开更多
关键词 MODIFIED Atomic Orbital Theory Variational Calculations Correlated WAVEFUNCTION Energies GROUND-STATE Doubly Excited States HELIUM Isoelectronic Sequence Atoms and Ions
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Isolation and Molecular Characterization of <i>Mycoplasma mycoides</i>Subspecie <i>mycoides</i>in 3 Agro Ecological Zones of Nasarawa State, Nigeria 认领
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作者 Livinus Terhemba Ikpa Dauda Garba Bwala +6 位作者 Paul Idoko Ankeli Adamu Ahmad Kaikabo Mugla Salma Maichibi Issa Atanda Maurina Jerry Ngutor Abenga Nicholas Douglas Nwankpa Mohammed Ignatius Adah 《兽医学(英文)》 2020年第2期15-26,共12页
Contagious bovine pleuropneumonia is a disease caused by Mycoplasma mycoides subspecie mycoides, a transboundary animal disease causing serious devastation to cattle producers in Africa. The study was designed to iden... Contagious bovine pleuropneumonia is a disease caused by Mycoplasma mycoides subspecie mycoides, a transboundary animal disease causing serious devastation to cattle producers in Africa. The study was designed to identify and characterize the pathogenic member of mycoplasma cluster the Mycoplasma mycoides subspecie mycoides (Mmm) isolated from cattle infected with the disease. Three hundred (300) samples of nasal swabs and pleural fluid from cattle showing signs of CBPP were analyzed using culture and biochemical identification techniques and polymerase chain reaction (PCR) using specific primers to determine the prevalence of contagious bovine pleuropneumonia in Nasarawa State, Nigeria. Isolation recorded a prevalence of 4% and PCR recorded a prevalence of 67.7%. Isolates subjected to PCR analysis produced an amplicon size of 548 bp and 1.1 k bp respectively for the Mycoplasma mycoides cluster and Mycoplasma mycoides subspecie mycoides. Sequencing of the 16 S rRNA gene blast search revealed 96% to 99% sequence homology of Mycoplasma mycoides subspecie mycoides compared with 14 available sequences in the gen bank at NCBI. Based on this investigation mass vaccination of cattle is recommended, isolation and PCR techniques could be used as diagnostic tools for CBPP disease in three agro ecological zones of Nasarawa state, Nigeria. 展开更多
关键词 Polymerase Chain Reaction AMPLICON Size Specific Primer Sequence HOMOLOGY MYCOPLASMA mycoides
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M序列伪码调相脉冲多普勒引信抗干扰性能研究 认领 被引量:1
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作者 于洪海 闫晓鹏 +2 位作者 贾瑞丽 李泽 王建涛 《兵工学报》 EI CAS CSCD 北大核心 2020年第3期417-425,共9页
针对基于m序列伪码调相的脉冲多普勒引信伪随机序列可选择范围少、易被破解等问题,提出基于M序列伪码调相的脉冲多普勒引信抗干扰方法。利用M序列非线性结构复杂、数量巨大而不易被截获和重构的特性,设计了基于M序列的伪码调相脉冲多普... 针对基于m序列伪码调相的脉冲多普勒引信伪随机序列可选择范围少、易被破解等问题,提出基于M序列伪码调相的脉冲多普勒引信抗干扰方法。利用M序列非线性结构复杂、数量巨大而不易被截获和重构的特性,设计了基于M序列的伪码调相脉冲多普勒引信;理论推导了引信探测过程中的各级响应表达式,并以处理增益为指标对M序列伪码调相脉冲多普勒引信抗干扰性能进行定量计算。理论计算和实验研究结果表明,与m序列相比,基于M序列的伪码调相脉冲多普勒引信能够进一步提高其抗有源干扰的能力。 展开更多
关键词 伪码调相脉冲多普勒引信 抗干扰性能 M序列 M序列 处理增益
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一些正弦函数级数的敛散性 认领
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作者 杜先云 任秋道 《绵阳师范学院学报》 2020年第5期1-4,15共5页
本文给出任意项级数收敛判定方法:如果级数∑n=1∞ an的项添加括号后所成的级数收敛且limn→∞an=0,则该级数收敛.由此获得:设C={ai|ai∈Z,i=0,1,…,k},D={a2j|a2j=2r2j+1∈C,r2j∈Z},E={a2j+1|a2j+1=2r2j+1+1∈C,r2j+1∈Z}且|D|=2p+1,|... 本文给出任意项级数收敛判定方法:如果级数∑n=1∞ an的项添加括号后所成的级数收敛且limn→∞an=0,则该级数收敛.由此获得:设C={ai|ai∈Z,i=0,1,…,k},D={a2j|a2j=2r2j+1∈C,r2j∈Z},E={a2j+1|a2j+1=2r2j+1+1∈C,r2j+1∈Z}且|D|=2p+1,|E|=2q,p,q∈Z,则级数∑n=1∞sinπ/2(a0nk+a1nk-1+…+ak)/n发散,否则收敛.同时得到:∑n=1∞sinπ/2n2s+1/n收敛,级数∑n=1∞sinπ/2n2s/n发散,其中s∈N. 展开更多
关键词 数列 数列收敛 级数收敛
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免疫相关基因在绝经后骨质疏松症患者外周血白细胞中的表达 认领
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作者 陈天宁 杨铁毅 +4 位作者 邵进 孔德策 刘树义 周文超 张岩 《中国组织工程研究》 CAS 北大核心 2020年第25期4033-4038,共6页
背景:目前认为骨骼是一种免疫器官,在骨髓中形成的多种免疫细胞可与骨骼系统的细胞相互作用,共同调控骨代谢。研究绝经后骨质疏松症的发病机制,寻找其治疗的分子靶标和信号通路,有助于其预防和治疗。目的:利用RNA-Seq技术,探讨绝经后骨... 背景:目前认为骨骼是一种免疫器官,在骨髓中形成的多种免疫细胞可与骨骼系统的细胞相互作用,共同调控骨代谢。研究绝经后骨质疏松症的发病机制,寻找其治疗的分子靶标和信号通路,有助于其预防和治疗。目的:利用RNA-Seq技术,探讨绝经后骨质疏松症患者外周血白细胞中与免疫相关的基因表达谱的变化。方法:选取因发生骨折住院治疗的绝经后0-20年的女性40人,首先采用Lunar Prodigy双能X射线骨密度仪扫描后,分为骨量正常组(T>-1)和骨质疏松组(T<-2.5)。全转录组测序(RNA-seq)分别抽取2组各5人的外周血样本,分离白细胞后提取总RNA,筛选2组的表达差异基因并进行GO富集分析,筛选免疫相关表达基因并进行KEGG信号通路分析,收集2组各20人的外周血样本采用Real-time PCR验证KEGG PATHWAY生物信息学分析的结果。研究方案的实施符合上海市浦东新区公利医院的相关伦理要求(20170301)。结果与结论:①骨质疏松组与骨量正常组相比,表达差异在2倍以上且具有统计学意义的基因为187个(其中表达上调131个,表达下调56个),其中与免疫相关的表达差异基因为29个(其中表达上调25个,表达下调4个);②KIR3DL1、KIR3DL2、KIR2DL4、KLRD1及HSPA6在2组中的表达差异有显著性意义(P<0.05);③结果说明,KEGG信号通路分析显示上述5个基因在自然杀伤细胞介导的细胞毒作用中发挥重要作用。KIR3DL1、KIR3DL2、KIR2DL4、KLRD1及HSPA6参与的自然杀伤细胞介导的细胞毒作用可能与绝经后骨质疏松症的发生密切相关。 展开更多
关键词 绝经后骨质疏松症 外周血白细胞 RNA SEQUENCE 免疫相关基因
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PCR Based Detection and Phylogenetic Analysis of Fowl Adenovirus Strains Isolated from 2019 Epidemic from Punjab and Sindh, Pakistan 认领
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作者 Nadeem Sharif Muhammad Danish Mehmood +5 位作者 Syed Zeeshan Haider Naqvi Huma Anwar ul-Haq Syed Shoaib Ahmed Muhammad Usman Ghani Muhammad Shoaib Mubashir Hussain 《美国分子生物学期刊(英文)》 2020年第3期246-258,共13页
Hydro-Pericardium Hepatitis (HPH) is an emerging infectious disease of commercial poultry, caused by different serotypes of Fowl Adeno Virus. The vertical transmission of the virus into the progeny may results in deva... Hydro-Pericardium Hepatitis (HPH) is an emerging infectious disease of commercial poultry, caused by different serotypes of Fowl Adeno Virus. The vertical transmission of the virus into the progeny may results in devastating damage, causing huge economic losses to its farmers. In present study, molecular typing is performed on basis of partially conserved hexon gene sequences, using a unique set of primers having common reverse oligo for simultaneous detection of FAdV1, FAdV-4 and FAdV-11. A total of 14 fowl adeno virus strains were isolated from 100 suspected adeno virus liver samples, collected from different districts in Pakistan, between 2018 and 2019. FASTA’s sequence alignment and phylogenetic analysis revealed that out of the 14, one isolate which belonged to group A showed 27% similarity with FAdV-1, while three isolates showed 99%, 95% & 45% similarity to FAdV-4 (Group C). Whereas, ten isolates showed more than 99% similarity to FAdV-11 (Group D). The serotypes FAdV1, FAdV-4 and FAdV-11 are prevailing in the breeder and broilers. These results hold great importance in rapid, reliable and simultaneous detection of the three FAdV serotypes. Therefore, fowl adeno virus vaccine production for commercial poultry shall be according to the prevalent field serotypes. 展开更多
关键词 Hydro-Pericardium Hepatitis (HPH) Hexon Gene Polymerase Chain Reaction Phylogenetic Analysis Sanger’s Sequence
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On the Occurrences of Fractures in Wrench Zones 认领
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作者 Shuping Chen 《力学国际期刊(英文)》 2020年第3期27-38,共12页
The formation conditions and time sequences for various types of wrench-related fractures are not clear. Based on a parabola-type failure criterion, this paper has gotten new insights on those questions. In a simple s... The formation conditions and time sequences for various types of wrench-related fractures are not clear. Based on a parabola-type failure criterion, this paper has gotten new insights on those questions. In a simple shear, the occurrence of either tensional fractures or Riedel shears is controlled by the ratio (Rtc) of tensile strength to cohesion. In a pure shear, the occurrence of either second order tensional fractures or second order Riedel shears is controlled by the ratio (Rtci) of tensile strength to cohesion, given a constant inner frictional coefficient. Where the Rtc or the Rtci is less than a certain value, the en echelon tensional fractures will occur first. Where the Rtc or the Rtci is bigger than the certain value, the Riedel shears will occur first. Where the Rtc or the Rtci is equal to the certain value, the en echelon tensional fractures and the Riedel shears will occur simultaneously. The understandings will enhance the research on wrench related fractures and will be of significance in petroleum exploration and development, because fractures are both important accumulation spaces and key migration paths for oil and gas. 展开更多
关键词 WRENCH Simple SHEAR PURE SHEAR Tensional Fracture Riedel SHEAR Time SEQUENCE
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一道数列极限题的注记 认领
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作者 赵军方 《大学数学》 2020年第1期110-114,共5页
用几何方法分析了高等数学中的一道数列求极限的题目,直观地显示了该数列趋向于极限的方式.并把极限的结果从实数域中拓展到复数域中,指出了该数列在复数域趋向于极限的方式是螺旋的,在实数域中趋向于极限的方式是沿直线靠近的.最后类... 用几何方法分析了高等数学中的一道数列求极限的题目,直观地显示了该数列趋向于极限的方式.并把极限的结果从实数域中拓展到复数域中,指出了该数列在复数域趋向于极限的方式是螺旋的,在实数域中趋向于极限的方式是沿直线靠近的.最后类比该数列,构造出相似数列的求极限问题. 展开更多
关键词 数列 极限 复数数列 几何解释
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Exact Solution to an Extremal Problem on Graphic Sequences with a Realization Containing Every 2-Tree on k Vertices 认领
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作者 De Yan ZENG Dong Yang ZHAI Jian Hua YIN 《数学学报:英文版》 SCIE CSCD 2020年第4期462-486,共25页
A simple graph G is a 2-tree if G=K3,or G has a vertex v of degree 2,whose neighbors are adjacent,and G-v is a 2-tree.Clearly,if G is a 2-tree on n vertices,then |E(G)|=2 n-3.A non-increasing sequence π=(d1,...,dn) o... A simple graph G is a 2-tree if G=K3,or G has a vertex v of degree 2,whose neighbors are adjacent,and G-v is a 2-tree.Clearly,if G is a 2-tree on n vertices,then |E(G)|=2 n-3.A non-increasing sequence π=(d1,...,dn) of nonnegative integers is a graphic sequence if it is realizable by a simple graph G on n vertices.[Acta Math.Sin.Engl.Ser.,25,795-802(2009)] proved that if k≥2,n≥9/2 k^22+19/2 k and π=(d1,...,dn) is a graphic sequence with∑i=1^n di>(k-2)n,then π has a realization containing every 1-tree(the usual tree) on k vertices.Moreover,the lower bound(k-2)n is the best possible.This is a variation of a conjecture due to Erdos and Sos.In this paper,we investigate an analogue problem for 2-trees and prove that if k≥3 is an integer with k≡i(mod 3),n≥ 20[k/3] 2+31[k/3]+12 and π=(d1,...,dn) is a graphic sequence with ∑i=1^n di>max{k-1)(n-1), 2 [2 k/3] n-2 n-[2 k/3] 2+[2 k/3]+1-(-1)i}, then π has a realization containing every 2-tree on k vertices.Moreover,the lower bound max{(k-1)(n-1), 2[2 k/3]n-2 n-[2 k/3] 2+[2 k/3]+1-(-1)i}is the best possible.This result implies a conjecture due to [Discrete Math.Theor.Comput.Sci.,17(3),315-326(2016)]. 展开更多
关键词 Degree sequence graphic sequence REALIZATION 2-tree
文章速递JIT生产方式在现代汽车装配制造中的应用 认领
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作者 史晓薇 《现代制造技术与装备》 2020年第10期154-156,共3页
现代汽车制造业采用柔性生产方式,以实现品种多、批量小、交货期严格的订单式生产,使企业迅速准确地适应市场变化,增加企业竞争力。保证生产线高效运转的同时,大幅降低零件库存成本尤为重要,因此JIT生产方式在汽车制造企业中得到了广泛... 现代汽车制造业采用柔性生产方式,以实现品种多、批量小、交货期严格的订单式生产,使企业迅速准确地适应市场变化,增加企业竞争力。保证生产线高效运转的同时,大幅降低零件库存成本尤为重要,因此JIT生产方式在汽车制造企业中得到了广泛应用。 展开更多
关键词 汽车装配 JIT生产方式 信息系统 排序
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The Asymptotic Attractor of the Damped Navier-Stokes System 认领
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作者 Qian JIANG Tingwei RUAN Hong LUO 《数学研究及应用:英文版》 CSCD 2020年第3期313-319,共7页
In this paper, the asymptotic attractor of the 2-D damped and driven Navier-Stokes equation is studied by constructing a finite-dimensional solution sequence, and it is proved that this solution sequence approximates ... In this paper, the asymptotic attractor of the 2-D damped and driven Navier-Stokes equation is studied by constructing a finite-dimensional solution sequence, and it is proved that this solution sequence approximates the global attractor infinitely after a long time. The dimension estimate of the asymptotic attractor is obtained in the end. 展开更多
关键词 asymptotic attractor asymptotic solution sequence damped navier-stokes equation
伊通盆地梁家构造带扇体预测及成藏条件分析 认领
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作者 王雷 袁立川 +5 位作者 邹晓品 柯钦 张莹 王泽权 闫巧洁 王芳 《物探化探计算技术》 CAS 2020年第1期1-8,共8页
伊通盆地梁家构造带为富油区带,多口井获工业油气流,油气成藏主控因素为构造背景下的岩性油藏。由于梁家构造带源近流短,储层横向变化快,预测难度大。利用层序地层学原理建立等时格架,在此基础上开展层序约束扇体和砂体预测,预测出了扇... 伊通盆地梁家构造带为富油区带,多口井获工业油气流,油气成藏主控因素为构造背景下的岩性油藏。由于梁家构造带源近流短,储层横向变化快,预测难度大。利用层序地层学原理建立等时格架,在此基础上开展层序约束扇体和砂体预测,预测出了扇体范围和砂体分布。结合构造特征及源储配置关系分析,进一步明确二号断层下降盘鼻状构造背景下的扇三角洲前缘水下分流河道砂体为油气富集区带,为井位部署和储量升级提供借鉴。 展开更多
关键词 梁家构造带 层序 扇体 控藏
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Novel Primate Bocaparvovirus Species 3 Identified in Wild Macaca Mulatta in China 认领
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作者 Yuanyun Ao Zhaojun Duan 《中国病毒学:英文版》 SCIE CAS CSCD 2020年第1期34-42,共9页
Primate bocaparvovirus(BOV) is a possible cause of respiratory disorders and gastroenteritis in humans. However, the diversity and evolution of these viruses remain largely unknown, despite the identification of a gro... Primate bocaparvovirus(BOV) is a possible cause of respiratory disorders and gastroenteritis in humans. However, the diversity and evolution of these viruses remain largely unknown, despite the identification of a growing number of BOVs in non-human primates(NHPs). Here, we report the identification of a novel BOV(provisionally named Macaca mulatta bocaparvovirus [MmBOV]) in the feces of wild Macaca mulatta in China by viral metagenomic analysis. Seven of 400 fecal samples from Macaca mulatta were positive for MmBOV. An almost complete genome sequence of 4,831 nucleotides was obtained, which had genomic organization and protein motifs similar to human bocaviruses(HOBVs), and shared characteristically low G/C content and weak codon usage bias. Sequence analyses of NS1, NP1, and VP1 revealed that Mm BOV was most closely related to HBOV4 of Primate bocaparvovirus 2(approximately 68.4%/70.6%, 73.3%/67.6%, and 70.4%/73.1% nucleotide/amino acid identities, respectively). Additionally, phylogenetic analysis revealed that Mm BOV formed an independent peripheral branch, but clustered closely with those of the Primate bocaparvovirus species in the BOV genus(particularly HBOV4). These data strongly suggest that HBOV4 originated from NHP bocaparvoviruses around 200–300 years ago, and that NHPs may act as HBOV reservoirs. Following the International Committee of Taxonomy for Viruses guidelines, we propose Mm BOV as a new species(tentatively named Primate bocaparvovirus 3) in the genus Bocaparvovirus, which is the first report of a novel species of primate BOV. Our data facilitate future research on the genetic diversity and evolution of primate bocaparvoviruses and highlight the importance of bocaparvovirus surveys in wild NHPs. 展开更多
关键词 PRIMATE bocaparvovirus(BOV) NOVEL species MACACA MULATTA Sequence ANALYSIS Phylogenetic ANALYSIS
回声话语的认同功能——基于互动与立场表达的视角 认领
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作者 朱军 《语言教学与研究》 CSSCI 北大核心 2020年第4期91-102,共12页
学界对回声话语的讨论倾向于根据类型确定功能,认为其功能多样化,但缺乏对核心功能的概括和解释。回声话语是一种具有互动性和立场表达功能的话语手段,其核心功能是表明说话者对对方观点或立场不同程度的"认同",主要有认同、... 学界对回声话语的讨论倾向于根据类型确定功能,认为其功能多样化,但缺乏对核心功能的概括和解释。回声话语是一种具有互动性和立场表达功能的话语手段,其核心功能是表明说话者对对方观点或立场不同程度的"认同",主要有认同、趋同、求证、质疑、不认同等类型,另外情感色彩上也有积极和消极之别。"认同"观能够较为统一地解释各种回声话语现象。语料统计还表明,总体上表认同度高的回声话语更为常见,话语序列、会话场景和机构性会话中的权势关系等因素对具体话语功能的选择产生不同程度的影响。 展开更多
关键词 回声话语 认同 核心/具体功能 序列 话语场景
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断裂-层序双控机制下的热液活动及成储效应——以塔里木盆地塔河、玉北地区下奥陶统为例 认领
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作者 孙福宁 胡文瑄 +3 位作者 胡忠亚 刘永立 康逊 朱峰 《石油与天然气地质》 EI CAS CSCD 北大核心 2020年第3期558-575,共18页
塔里木盆地下古生界碳酸盐岩广泛发育,是油气勘探的重要领域。以塔里木盆地塔河、玉北地区下奥陶统为例,通过岩心观察、薄片鉴定、电子探针、C、O、Sr同位素以及REE元素分析,结合测井及地震资料,探讨了断裂系统和层序地层格架中的热液... 塔里木盆地下古生界碳酸盐岩广泛发育,是油气勘探的重要领域。以塔里木盆地塔河、玉北地区下奥陶统为例,通过岩心观察、薄片鉴定、电子探针、C、O、Sr同位素以及REE元素分析,结合测井及地震资料,探讨了断裂系统和层序地层格架中的热液活动及成储效应。研究认为:中-细晶白云岩遭受富硅质热液流体改造强烈,表现为热褪色现象、鞍状白云石充填和充填白云石、方解石、玉髓、黄铁矿等多种矿物组合沉淀,以及较高的SiO2、FeO、MnO、BaO含量、较低的SrO含量和87Sr/86Sr值、偏负的δ18O值、较低的∑REE含量、明显的Eu正异常和Ce负异常。热液流体对白云岩储层的改造主要表现为溶蚀作用、重结晶作用和充填作用三个方面,溶蚀作用形成的次生溶蚀孔隙成为最重要的储集空间。不同尺度断裂和三级层序甚至更短周期层序界面共同构成深部热液流体运移的输导体系,对热液活动及储层发育起到强烈的控制作用,并建立了塔里木盆地塔河、玉北地区下奥陶统蓬莱坝组断裂-层序双控机制下的热液活动及成储效应的概念模型。 展开更多
关键词 富硅质热液 次生溶蚀孔隙 白云岩储层 断裂 层序 下奥陶统 塔里木盆地
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