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文章速递Minimum Parametrization of the Cauchy Stress Operator 认领
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作者 J.-F. Pommaret 《现代物理(英文)》 2021年第4期453-482,共30页
When D: <span style="white-space:nowrap;"><span style="white-space:nowrap;"><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">... When D: <span style="white-space:nowrap;"><span style="white-space:nowrap;"><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&xi;</span></span></em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&rarr;</span></span><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&eta;</span></span></em><em><span style="white-space:nowrap;"></span></em><em></em></span> </span>is a linear differential operator, a “direct problem” is to find the generating compatibility conditions (CC) in the form of an operator D<sub>1</sub>: <span style="white-space:nowrap;"><span style="white-space:nowrap;"><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&eta;</span></span></em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&rarr;</span></span><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&xi;</span> </span></em></span></span>such that <span style="white-space:nowrap;">D<span style="white-space:nowrap;"><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&xi;</span></span></em></span>=<span style="white-space:nowrap;"><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&eta;</span></span></em></span></span> implies <span style="white-space:nowrap;">D<sub>1</sub><span style="white-space:nowrap;"><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&eta;</span></span></em></span>=0</span>. When D is involutive, the procedure provides successive first order involutive operators D1, ..., D<sub>n</sub>, when the ground manifold has dimension <em>n</em>, a result first found by M. Janet as early as in 1920, in a footnote. However, the link between this “Janet sequence” and the “Spencer sequence” first found by the author of this paper in 1978 is still not acknowledged. Conversely, when D<sub>1</sub> is given, a more difficult “inverse problem” is to look for an operator D: <span style="white-space:nowrap;"><span style="white-space:nowrap;"><em><em><span style="white-space:nowrap;">&xi;</span></em></em><span style="white-space:nowrap;">&rarr;</span><em><em><span style="white-space:nowrap;">&eta;</span></em><em></em><em></em> </em><em></em></span> </span>having the generating CC <span style="white-space:nowrap;">D<sub>1</sub><span style="white-space:nowrap;"><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">&eta;</span></span></em></span><em></em>=0</span>. If this is possible, that is when the differential module defined by D<sub>1</sub> is torsion-free, one shall say that the operator D<sub>1</sub> is parametrized by D and there is no relation in general between D and D<sub>2</sub>. The parametrization is said to be “minimum” if the differential module defined by D has a vanishing differential rank and is thus a torsion module. The solution of this problem, first found by the author of this paper in 1995, is still not acknowledged. As for the applications of the “differential double duality” theory to standard equations of physics (<em>Cauchy</em> and Maxwell equations can be parametrized while <em>Einstein</em> equations cannot), we do not know other references. When <span style="font-size:10.0pt;font-family:;" "="">erator in arbitrary dimension</span>=1 as in control theory, the fact that controllability is a “built in” property of a control system, amounting to the existence of a parametrization and thus not depending on the choice of inputs and outputs, even with variable coefficients, is still not acknowledged by engineers. The parametrization of the <em>Cauchy</em> stress operator in arbitrary dimension <em>n</em> has nevertheless attracted, “separately” and without any general “guiding line”, many famous scientists (G.B. Airy in 1863 for <em>n </em>= 2, J.C. Maxwell in 1863, G. Morera and E. Beltrami in 1892 for <em style="white-space:normal;">n </em><span style="white-space:normal;">= 3</span> , A. Einstein in 1915 for <em style="white-space:normal;">n </em><span style="white-space:normal;">= 4</span> ). The aim of this paper is to solve the minimum parametrization problem in arbitrary dimension and to apply it through effective methods that could even be achieved by using computer algebra. Meanwhile, we prove that all these works are using the <em>Einstein</em> operator which is self-adjoint and not the <em>Ricci</em> operator, a fact showing that the <em>Einstein</em> operator, which cannot be parametrized, has already been exhibited by Beltrami more than 20 years before <em>Einstein</em>. As a byproduct, they are all based on the same confusion between the so-called <em>div</em> operator induced from the <em>Bianchi </em>operator D<sub>2</sub> and the <em>Cauchy</em> operator which is the formal adjoint of the Killing operator D parametrizing the Riemann operator D<sub>1</sub> for an arbitrary <em>n</em>. We prove that this purely mathematical result deeply questions the origin and existence of gravitational waves. We also present the similar motivating situation met in the study of contact structures when <em>n</em> = 3. Like the Michelson and Morley experiment, it is thus an open historical problem to know whether <em>Einstein</em> was aware of these previous works or not, but the comparison needs no comment. 展开更多
关键词 Differential Operator Differential Sequence Killing Operator Riemann Operator Bianchi Operator Cauchy Operator Electromagnetism Elasticity General Relativity Gravitational Waves
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Analysis of the N Protein Sequence Variability in 13 Isolated PRRSV Strains from China 认领
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作者 Yang Xia Baodan Huang +4 位作者 Bin Wu Yi Zhang Maole Yan Yan Li Jida Li 《生物科学与医学(英文)》 2021年第2期63-75,共13页
<strong>Object</strong>: To analyze porcine reproductive and respiratory syndrome virus (PRRSV) strains from 13 infection cases via the N protein gene and its encoded amino acid sequence and to provide a t... <strong>Object</strong>: To analyze porcine reproductive and respiratory syndrome virus (PRRSV) strains from 13 infection cases via the N protein gene and its encoded amino acid sequence and to provide a theoretical basis for the epidemiological study, prevention and control of porcine reproductive and respiratory syndrome (PRRS). <strong>Methods</strong>: In clinically suspected PRRSV infections, viruses were isolated by extracting viral nucleic acid and amplifying the N protein gene by RT-PCR. Then, the product was purified and sequenced to acquire the whole gene sequence of the N protein and its encoded amino acid sequence. DNASTAR software was used to analyze the homology, the genetic evolution and the derivation of the variability of amino acids of the N protein gene from 13 PRRSV strains and classical domestic and foreign strains. <strong>Results</strong>: Among the thirteen strains of PRRSV isolated from this study, ten strains had the greatest homology with the JXA1 strain (98.9% - 100%), and they belonged to the sublineage 8.7. The remaining three strains had the greatest homology with the NADC30 strain (95.4% - 97.1%), and they belonged to lineage one. The analysis of the variability of N protein amino acids showed that there were high frequency mutations in the five loci of 13 isolated strains of PRRSV as follows: 15th amino acid (10/13), 46<sup>th</sup> amino acid (11/13), 91st amino acid (10/13), 109th amino acid (10/13), and 117th amino acid (10/13). <strong>Conclusion</strong>: In recent years, sublineage 8.7 was the dominant pedigree in field PRRSV epidemic strains in China with lineage one occupying a certain proportion of the field. Four high frequency mutations existed in N protein antigen epitopes of isolated strains from the region. The nuclear localization signal (NLS) structure, specifically the 46<sup>th</sup> amino acid residue of the N protein, was mutated and genetically stable. 展开更多
关键词 PRRSV Nucleocapsid Protein Nuclear Location Signal EPIDEMIOLOGICAL Amino Acid Sequence
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Variational Calculations of Energies of the (2<i>snl</i>) <sup>1,3</sup><i>L<sup>π</sup></i>and (2<i>pnl</i>) <sup>1,3 </sup><i>L<sup>π</sup></i>Doubly Excited States in Two-Electron Systems Applying the Screening Constant per Unit Nuclear Charge 认领
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作者 Momar Talla Gning Ibrahima Sakho +5 位作者 Maurice Faye Malick Sow Babou Diop Jean Kouhissoré Badiane Diouldé Ba Abdourahmane Diallo 《现代物理(英文)》 2021年第3期328-352,共25页
In this paper, resonance energies and excitation energies of doubly 2<em>sns</em> <sup>1,3</sup><em>S</em><sup>e</sup>, 2<em>snp</em> <sup>1,3</sup&... In this paper, resonance energies and excitation energies of doubly 2<em>sns</em> <sup>1,3</sup><em>S</em><sup>e</sup>, 2<em>snp</em> <sup>1,3</sup><em>P</em><sup>0</sup>, 2<em>pnp</em> <sup>1,3</sup><em>D</em><sup>e</sup>, 2<em>pnd</em> <sup>1,3</sup><em>F</em><sup>0</sup> and 2<em>pnf</em> <sup>1,3</sup><em>G</em><sup>e</sup> excited states of the helium isoelectronic sequence with <em>Z</em> <span style="white-space:nowrap;">≤</span> 10 are calculated. Calculations are carried out in the framework of the variational procedure of the formalism of the Screening Constant per Unit Nuclear Charge (SCUNC). New correlated wave function of Hylleraas type is used. Precise resonance and excitation energies are tabulated and good agreement is obtained when a comparison is made with available literature values. 展开更多
关键词 Doubly Excited States Helium Isoelectronic Sequence Screening Constant per Unit Nuclear Charge (SCUNC) Correlated Wave Function Resonance Energy Excitation Energies
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Identical Machine Scheduling Problem with Sequence-Dependent Setup Times: MILP Formulations Computational Study 认领
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作者 Farouk Yalaoui Nhan Quy Nguyen 《美国运筹学期刊(英文)》 2021年第1期15-34,共20页
This work aims to give a systematic construction of the two families of mixed-integer-linear-programming (MILP) formulations, which are graph-<span style="font-family:;" "=""> </span&... This work aims to give a systematic construction of the two families of mixed-integer-linear-programming (MILP) formulations, which are graph-<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">based and sequence-based, of the well-known scheduling problem<img src="Edit_41010f25-7ca5-482c-89be-790fad4616e1.png" alt="" /></span><span style="font-family:Verdana;text-align:justify;">. Two upper bounds of job completion times are introduced. A numerical test result analysis is conducted with a two-fold objective 1) testing the performance of each solving methods, and 2) identifying and analyzing the tractability of an instance according to the instance structure in terms of the number of machines, of the jobs setup time lengths and of the jobs release date distribution over the scheduling horizon.</span> <div> <span style="font-family:Verdana;text-align:justify;"><br /> </span> </div> 展开更多
关键词 Identical Machine Scheduling Problem Release Date Sequence Dependent Setup Time
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Fibonacci Sequence Found in Parkfield Earthquake 认领
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作者 Guangmeng Guo 《地球科学国际期刊(英文)》 2021年第1期1-5,共5页
USA scientists found </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span>&l... USA scientists found </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">22-year cycle in Parkfield earthquake sequence, and they predicted that the next quake would come in 1988 ± 5 with 95% possibility, while the quake happened in 2004, which is 11 years later than the prediction. Here, we reanalyze the Parkfield earthquake sequence, and find 11-year cycle;multiple 11-year cycle and Fibonacci sequence existed for earthquake. With these methods, the 2004 earthquake can be predicted well. We also predict that the next earthquake may occur in 2031-2032. 展开更多
关键词 Fibonacci Sequence Parkfield Earthquake 11-Year Cycle
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Subsampling bias and the best-discrepancy systematic cross validation 认领
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作者 Liang Guo Jianya Liu Ruodan Lu 《中国科学:数学英文版》 SCIE 2021年第1期197-210,共14页
Statistical machine learning models should be evaluated and validated before putting to work.Conventional k-fold Monte Carlo cross-validation(MCCV)procedure uses a pseudo-random sequence to partition instances into k ... Statistical machine learning models should be evaluated and validated before putting to work.Conventional k-fold Monte Carlo cross-validation(MCCV)procedure uses a pseudo-random sequence to partition instances into k subsets,which usually causes subsampling bias,inflates generalization errors and jeopardizes the reliability and effectiveness of cross-validation.Based on ordered systematic sampling theory in statistics and low-discrepancy sequence theory in number theory,we propose a new k-fold cross-validation procedure by replacing a pseudo-random sequence with a best-discrepancy sequence,which ensures low subsampling bias and leads to more precise expected-prediction-error(EPE)estimates.Experiments with 156 benchmark datasets and three classifiers(logistic regression,decision tree and na?ve bayes)show that in general,our cross-validation procedure can extrude subsampling bias in the MCCV by lowering the EPE around 7.18%and the variances around 26.73%.In comparison,the stratified MCCV can reduce the EPE and variances of the MCCV around 1.58%and 11.85%,respectively.The leave-one-out(LOO)can lower the EPE around 2.50%but its variances are much higher than the any other cross-validation(CV)procedure.The computational time of our cross-validation procedure is just 8.64%of the MCCV,8.67%of the stratified MCCV and 16.72%of the LOO.Experiments also show that our approach is more beneficial for datasets characterized by relatively small size and large aspect ratio.This makes our approach particularly pertinent when solving bioscience classification problems.Our proposed systematic subsampling technique could be generalized to other machine learning algorithms that involve random subsampling mechanism. 展开更多
关键词 subsampling bias cross validation systematic sampling low-discrepancy sequence best-discrepancy sequence
文章速递An Effective Cloud Workflow Scheduling Approach Combining PSO and Idle Time Slot-Aware Rules 认领
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作者 Yun Wang Xingquan Zuo 《自动化学报:英文版》 SCIE EI CSCD 2021年第5期1079-1094,共16页
Workflow scheduling is a key issue and remains a challenging problem in cloud computing.Faced with the large number of virtual machine(VM)types offered by cloud providers,cloud users need to choose the most appropriat... Workflow scheduling is a key issue and remains a challenging problem in cloud computing.Faced with the large number of virtual machine(VM)types offered by cloud providers,cloud users need to choose the most appropriate VM type for each task.Multiple task scheduling sequences exist in a workflow application.Different task scheduling sequences have a significant impact on the scheduling performance.It is not easy to determine the most appropriate set of VM types for tasks and the best task scheduling sequence.Besides,the idle time slots on VM instances should be used fully to increase resources'utilization and save the execution cost of a workflow.This paper considers these three aspects simultaneously and proposes a cloud workflow scheduling approach which combines particle swarm optimization(PSO)and idle time slot-aware rules,to minimize the execution cost of a workflow application under a deadline constraint.A new particle encoding is devised to represent the VM type required by each task and the scheduling sequence of tasks.An idle time slot-aware decoding procedure is proposed to decode a particle into a scheduling solution.To handle tasks'invalid priorities caused by the randomness of PSO,a repair method is used to repair those priorities to produce valid task scheduling sequences.The proposed approach is compared with state-of-the-art cloud workflow scheduling algorithms.Experiments show that the proposed approach outperforms the comparative algorithms in terms of both of the execution cost and the success rate in meeting the deadline. 展开更多
关键词 Cloud computing idle time slot particle swarm optimization task scheduling sequence workflow scheduling
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文章速递Ratcheting behavior of notched stainless steel samples subjected to asymmetric loading cycles 认领
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作者 A.Shekarian A.Varvani‑Farahani 《钢铁研究学报:英文版》 SCIE EI CSCD 2021年第1期86-97,共12页
The ratcheting response of 316 stainless steel samples at the vicinity of notch roots under single-and multi-step loading conditions is evaluated.Multi-step tests were conducted to examine local ratcheting at differen... The ratcheting response of 316 stainless steel samples at the vicinity of notch roots under single-and multi-step loading conditions is evaluated.Multi-step tests were conducted to examine local ratcheting at different low–high–high and high–low–low loading sequences.The stress levels over loading steps and their sequences highly influenced ratcheting magnitude and rate.The change of stress level from low to high promoted ratcheting over proceeding cycles while ratcheting strains dropped in magnitude for opposing sequence where stress level dropped from high to low.Local ratcheting strain values at the vicinity of notch root were found noticeably larger than nominal ratcheting values measured at farer distances from notch edge through use of strain gauges.Ratcheting values in both mediums of local and nominal were promoted as notch diameter increased.To assess progressive ratcheting response and stress relaxation concurrently,the Ahmadzadeh-Varvani(A-V)kinematic hardening rule was coupled with Neuber’s rule enabling to calculate local stress at notch root of steel samples.Local stress/strain values were progressed at notch root over applied asymmetric stress cycles resulting in ratcheting buildup through A-V model.The relaxation of stress values at a given peak-valley strain event was governed through the Neuber’s rule.Experimental ratcheting data were found agreeable with those predicted through the coupled framework. 展开更多
关键词 Ratcheting strain Notch root Step-loading Loading sequence Kinematic hardening rule Neuber’s rule
文章速递One-pth Riordan Arrays in the Construction of Identities 认领
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作者 Tianxiao HE 《数学研究及应用:英文版》 CSCD 2021年第2期111-126,共16页
For an integer p≥2 we construct vertical and horizontal one-pth Riordan arrays from a Riordan array.When p=2 one-pth Riordan arrays are reduced to well known half Riordan arrays.The generating functions of the A-sequ... For an integer p≥2 we construct vertical and horizontal one-pth Riordan arrays from a Riordan array.When p=2 one-pth Riordan arrays are reduced to well known half Riordan arrays.The generating functions of the A-sequences of vertical and horizontal one-pth Riordan arrays are found.The vertical and horizontal one-pth Riordan arrays provide an approach to construct many identities.They can also be used to verify some well known identities readily. 展开更多
关键词 Riordan array one-pth Riordan arrays A-sequence generating function identities
文章速递DFF-EDR:An Indoor Fingerprint Location Technology Using Dynamic Fusion Features of Channel State Information and Improved Edit Distance on Real Sequence 认领
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作者 Ke Han Yunfei Xu +1 位作者 Zhongliang Deng Jiawei Fu 《中国通信:英文版》 SCIE CSCD 2021年第4期40-63,共24页
Positioning technology based on wireless network signals in indoor environments has developed rapidly in recent years as the demand for locationbased services continues to increase.Channel state information(CSI)can be... Positioning technology based on wireless network signals in indoor environments has developed rapidly in recent years as the demand for locationbased services continues to increase.Channel state information(CSI)can be used as location feature information in fingerprint-based positioning systems because it can reflect the characteristics of the signal on multiple subcarriers.However,the random noise contained in the raw CSI information increases the likelihood of confusion when matching fingerprint data.In this paper,the Dynamic Fusion Feature(DFF)is proposed as a new fingerprint formation method to remove the noise and improve the feature resolution of the system,which combines the pre-processed amplitude and phase data.Then,the improved edit distance on real sequence(IEDR)is used as a similarity metric for fingerprint matching.Based on the above studies,we propose a new indoor fingerprint positioning method,named DFF-EDR,for improving positioning performance.During the experimental stage,data were collected and analyzed in two typical indoor environments.The results show that the proposed localization method in this paper effectively improves the feature resolution of the system in terms of both fingerprint features and similarity measures,has good anti-noise capability,and effectively reduces the localization errors. 展开更多
关键词 channel state information indoor positioning edit distance on real sequence dynamic parameters feature resolution
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文章速递Experimental research on the development of residual strain in seasonal frozen soil under freezing-thawing and impact type traffic loads 认领
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作者 Liu Tianhua Wang Miao 《地震工程与工程振动:英文版》 SCIE EI CSCD 2021年第2期335-345,共11页
Vehicle load is among the main factors affecting the deformation of subgrade soil.In this research study,the concept of impact type traffic load is introduced to investigate the effects of vehicle load based on the dy... Vehicle load is among the main factors affecting the deformation of subgrade soil.In this research study,the concept of impact type traffic load is introduced to investigate the effects of vehicle load based on the dynamic stress and displacement time histories acquired from seasonal frozen subgrade soils.Using freezing-thawing and dynamic triaxial tests and considering the amplitude and loading sequence of impact type traffic load,the residual deformation characteristics of subgrade soil under impact type traffic loads and freezing-thawing cycles is studied.It was found that under impact type traffic load,the residual deformation of soils increased sharply as the amplitude of impact type traffic load increased.It was also found that the increase in the amplitude of impact type traffic load led to the increase of residual deformation in a scale of power and exponential function.The amplitudes of impact type traffic load affect the development stress-strain path of the residual strain.After the soil experienced the proper amount of pre-vibration of the light load,residual deformation decreased by 15%.After freezing-thawing,the residual strain of soil increased as the amplitude of the impact type traffic loads increased.Also,when the amplification effect of freezing-thawing on the residual strain was basically stable,the residual deformation increased by about 10%.The peak impact type traffic load had a large effect on soil deformation after the freezing-thawing process,leading to the observation that of the earlier the peaks,the stronger the effect of freezing-thawing.After the soil was subjected to preloading with a small load,the influence of the freezing-thawing cycles gradually stabilized.The results may be useful in preventing and controlling the risk of subgrade soil failure when construction takes place spring thaw periods. 展开更多
关键词 impact type traffic load freezing-thawing dynamic triaxial test loading sequence residual strain
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文章速递Density-equicontinuity and Density-sensitivity 认领
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作者 Jie LI Si Ming TU 《数学学报:英文版》 SCIE CSCD 2021年第2期345-361,共17页
In this paper we introduce the notions of(Banach) density-equicontinuity and densitysensitivity. On the equicontinuity side, it is shown that a topological dynamical system is densityequicontinuous if and only if it i... In this paper we introduce the notions of(Banach) density-equicontinuity and densitysensitivity. On the equicontinuity side, it is shown that a topological dynamical system is densityequicontinuous if and only if it is Banach density-equicontinuous. On the sensitivity side, we introduce the notion of density-sensitive tuple to characterize the multi-variant version of density-sensitivity. We further look into the relation of sequence entropy tuple and density-sensitive tuple both in measuretheoretical and topological setting, and it turns out that every sequence entropy tuple for some ergodic measure on an invertible dynamical system is density-sensitive for this measure;and every topological sequence entropy tuple in a dynamical system having an ergodic measure with full support is densitysensitive for this measure. 展开更多
关键词 Density equicontinuity density sensitivity sequence entropy
文章速递Spectral study of V565 Mon: probable FU Ori-like or chemically peculiar star 认领
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作者 Hasmik Andreasyan 《天文和天体物理学研究:英文版》 SCIE CAS CSCD 2021年第3期128-132,共5页
We present a detailed spectroscopic study of pre-main sequence star V565 Mon,which is the illuminating star of the Parsamian 17 cometary nebula.Observations were performed with the 2.6 m telescope in Byurakan Astrophy... We present a detailed spectroscopic study of pre-main sequence star V565 Mon,which is the illuminating star of the Parsamian 17 cometary nebula.Observations were performed with the 2.6 m telescope in Byurakan Astrophysical Observatory on 2018 February 15.Radial velocities and equivalent widths of the most prominent lines of V565 Mon are presented.We build the spectral energy distribution and estimate the main parameters of the star,for example the obtained bolometric luminosity of V565 Mon is L_(V565)≈130 L_(⊙).Considering all features of V565 Mon,we come to the conclusion that this young intermediate-mass star belongs to some intermediate class between T Tau and HAeBe stars.Very unusual for a young star is the presence of strong absorption BaⅡlines in the spectrum.Possible explanations on this issue are discussed.Hence,we think that V565 Mon is a unique example,which can help to understand some open questions involved in the problem of nucleosynthesis in young stars. 展开更多
关键词 stars:pre-main sequence stars:variables:T Tauri Herbig Ae/Be stars:individual:V565 Mon
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文章速递多通道瞬变电磁法激励源降噪性能对比研究 认领
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作者 袁哲 张一鸣 +1 位作者 王旭红 高俊侠 《地球物理学进展》 CSCD 北大核心 2021年第1期425-433,共9页
对比研究双极性方波与m序列两种激励源在多通道瞬变电磁法(Multi-Transient Electromagnetic,MTEM)中的降噪性能,将大地脉冲响应的提取等效为辨识滤波器输出,通过分析辨识滤波器的谱特性量化评估不同激励源的降噪性能;通过数值模拟讨论... 对比研究双极性方波与m序列两种激励源在多通道瞬变电磁法(Multi-Transient Electromagnetic,MTEM)中的降噪性能,将大地脉冲响应的提取等效为辨识滤波器输出,通过分析辨识滤波器的谱特性量化评估不同激励源的降噪性能;通过数值模拟讨论两种激励源信号在工频噪声与白噪声环境下的大地脉冲响应辨识精度,模拟结果表明使用m序列替代双极性方波作为激励源能够大幅提高辨识精度,且残留噪声集中在码元频率及其谐频处;设计野外对比试验,采集两种激励源在弱/强干扰下的响应信号进行大地脉冲响应辨识,试验结果表明弱干扰环境下两种激励源的辨识精度相近,强干扰环境下m序列的降噪性能高于双极性方波,且噪声残留特征与数值模拟吻合. 展开更多
关键词 多通道瞬变电磁法 m序列 双极性方波 信噪比 降噪
迁安山叶口常州沟组一段岩石学特征 认领
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作者 肖竣文 《城市地质》 2021年第1期94-99,共6页
在沉积盆地分析中,对特定地质历史时期沉积的地层进行岩石学特征研究,是反映盆地演化特征和恢复古沉积环境的必要步骤。研究了迁安山叶口地区常州沟组一段的岩石学特征,对岩石沉积结构和构造进行了分析,对古水流方向进行了统计与分析,... 在沉积盆地分析中,对特定地质历史时期沉积的地层进行岩石学特征研究,是反映盆地演化特征和恢复古沉积环境的必要步骤。研究了迁安山叶口地区常州沟组一段的岩石学特征,对岩石沉积结构和构造进行了分析,对古水流方向进行了统计与分析,并探讨了该套地层形成时的古沉积环境。结果表明:本区常州沟组一段岩性为一套巨砾岩、砂岩,砂岩岩性以成分成熟度低的长石砂岩为主,巨砾岩砾石成分主要为成分成熟度较高的石英砂岩、石英岩和硅质岩。砾岩层序总体上表现为一个向上变细的正旋回,代表了水体向上逐渐变深的特征,3种典型的韵律特征形式。古水流优势方向为南东向,主要物源区可能位于今秦皇岛一带,沉积环境为干旱炎热气候下山间盆地中水流湍急的不成熟直流河,由于构造活动等因素逐渐向成熟的河流演变。 展开更多
关键词 岩石学 砾石 层序 沉积环境
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《汉志·诸子略》墨家类排序问题考辨 认领
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作者 白少雄 《重庆三峡学院学报》 2021年第1期106-118,共13页
《汉书·艺文志·诸子略》对诸子学派的学术源流进行梳理,但墨家学派的记载并不详细。基于《汉书·艺文志》(以下简称《汉志》)中双重编排原则的使用、互注之法的缺失、版本内容的改变等原因,致使墨家类著述的排序出现了错... 《汉书·艺文志·诸子略》对诸子学派的学术源流进行梳理,但墨家学派的记载并不详细。基于《汉书·艺文志》(以下简称《汉志》)中双重编排原则的使用、互注之法的缺失、版本内容的改变等原因,致使墨家类著述的排序出现了错位。通过对墨家类排序问题的重新考辨,可梳理出合理的墨家学派的发展脉络,符合《汉志》的写作宗旨,纠正《汉志》的错误记载,对于把握墨家学派的学术传承和历史地位,具有重要的学术史意义。 展开更多
关键词 《汉书·艺文志》 诸子略 墨家 排序 成因 学术史意义
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乳腺癌耐药细胞株外泌体中small RNA表达分析 认领
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作者 洪晓绿 黄小华 +2 位作者 程璐 赖金国 潘小平 《微循环学杂志》 2021年第1期13-19,共7页
目的:分析乳腺癌细胞株和乳腺癌耐药细胞株外泌体中small RNA的表达并比较其差异。方法:采用NextSeq CN500测序仪检测乳腺癌细胞株和乳腺癌耐药细胞株外泌体中small RNA的表达,DEGseq R软件包分析各small RNA表达差异。结果:与乳腺癌细... 目的:分析乳腺癌细胞株和乳腺癌耐药细胞株外泌体中small RNA的表达并比较其差异。方法:采用NextSeq CN500测序仪检测乳腺癌细胞株和乳腺癌耐药细胞株外泌体中small RNA的表达,DEGseq R软件包分析各small RNA表达差异。结果:与乳腺癌细胞株外泌体相比,乳腺癌耐药细胞株外泌体中960种miRNAs表达上调,29种miRNAs表达下调;44种piRNAs表达上调,60种piRNAs表达下调;93种tsRNAs表达上调,3种tsRNAs表达下调。结论:乳腺癌耐药细胞株外泌体与乳腺癌细胞外泌体间small RNA存在表达差异,可能是与乳腺癌细胞耐药有关。 展开更多
关键词 Small RNA 外泌体 乳腺癌耐药细胞株 测序
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Twin Anemia Polycythemia Sequence: Knowledge and Insights After 15 Years of Research 认领
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作者 Lisanne S.A.Tollenaar Enrico Lopriore +5 位作者 Dick Oepkes Monique C.Haak Frans J.C.M.Klumper Johanna M.Middeldorp Jeanine M.M.Van Klink Femke Slaghekke 《母胎医学杂志(英文)》 2021年第1期33-41,共9页
Twin anemia polycythemia sequence (TAPS) is a chronic form of unbalanced feto-fetal transfusion through minuscule placental anastomoses in monochorionic twin pregnancies, leading to anemia in the donor twin and polycy... Twin anemia polycythemia sequence (TAPS) is a chronic form of unbalanced feto-fetal transfusion through minuscule placental anastomoses in monochorionic twin pregnancies, leading to anemia in the donor twin and polycythemia in the recipient twin. TAPS can occur spontaneously in up to 5% of monochorionic twins or can arise in 2%-16% of cases after incomplete laser surgery for twin-twin transfusion syndrome. TAPS can develop across the entire second and third trimester. Antenatal diagnosis for TAPS is reached via Doppler measurement of the fetal middle cerebral artery peak systolic velocity, showing an increased velocity in the donor, combined with a decreased velocity in the recipient. Treatment options for TAPS include expectant management, preterm delivery, intrauterine blood transfusion with or without a partial exchange transfusion, fetoscopic laser surgery and selective feticide. The best treatment option is unclear and is currently being investigated in an international multicenter randomized trial (the TAPS trial). Spontaneous fetal demise occurs in 5%-11% of TAPS twins, more often in donors (8%-18%) than in recipients (2%-5%). Severe long-term neurodevelopmental impairment is seen in 9% of TAPS twins, with donors having an increased risk for cognitive impairment and hearing problems (15%). 展开更多
关键词 POLYCYTHEMIA ANEMIA Twin anemia polycythemia sequence Monochorionic twins Twin-twin transfusion syndrome PLACENTA
Complications of Monochorionic Diamniotic Twins: Stepwise Approach for Early Identification, Differential Diagnosis, and Clinical Management 认领
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作者 Taita Micheletti Elisenda Eixarch +2 位作者 Mar Bennasar Josep Maria Martinez Eduard Gratacos 《母胎医学杂志(英文)》 2021年第1期42-52,共11页
One in three monochorionic twins may develop complications during pregnancy. Monochorionic twins, especially monochorionic diamniotic (MCDA), present specific problems caused by the presence of interfetal placental an... One in three monochorionic twins may develop complications during pregnancy. Monochorionic twins, especially monochorionic diamniotic (MCDA), present specific problems caused by the presence of interfetal placental anastomoses. The first critical step in the management of MCDA twins is identification in the first trimester. Secondly, close follow-up every 2 weeks is mandatory to allow early diagnosis and timely treatment of twin-twin transfusion syndrome. Other potentially severe complications include selective fetal growth restriction, twin anemia polycythemia syndrome or single fetal death. Thirdly, a correct differential diagnosis is critical to establish the best therapy. This may represent a clinical challenge since MCDA twin complications often overlap. A simple diagnostic algorithm may be of great help to establish the right diagnosis and management option. In this review we summarize the main steps for the clinical follow-up, differential diagnosis, and targeted management of MCDA twins complications. 展开更多
关键词 Acute feto-fetal transfusion Discordant malformation Monochorionic diamniotic twin pregnancy Pregnancy TWIN Selective fetal growth restriction Single intrauterine fetal death Twin anemia-polycythemia sequence Twin-twin transfusion syndrome
A New Lower Bound on the Potential-Ramsey Number of Two Graphs 认领
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作者 Jin-zhi DU Jian-hua YIN 《应用数学学报:英文版》 SCIE 2021年第1期176-182,共7页
A nonincreasing sequenceπ=(d1,…,dn)of nonnegative integers is a graphic sequence if it is realizable by a simple graph G on n vertices.In this case,G is referred to as a realization ofπ.Given a graph H,a graphic se... A nonincreasing sequenceπ=(d1,…,dn)of nonnegative integers is a graphic sequence if it is realizable by a simple graph G on n vertices.In this case,G is referred to as a realization ofπ.Given a graph H,a graphic sequenceπis potentially H-graphic ifπhas a realization containing H as a subgraph.For graphs G1 and G2,the potential-Ramsey number rpot(G1,G2)is the smallest integer k such that for every k-term graphic sequenceπ,eitherπis potentially G1-graphic or the complementary sequenceπ=(k-1-dk,…,k-1-d1)is potentially G2-graphic.For 0≤k≤[t/2],denote Kt-k to be the graph obtained from Kt by deleting k independent edges.If k=0,Busch et al.(Graphs Combin.,30(2014)847-859)present a lower bound on rpot(G,Kt)by using the 1-dependence number of G.In this paper,we utilize i-dependence number of G for i≥1 to give a new lower bound on rpot(G,Kt-k)for any k with 0≤k≤[T/2].Moreover,we also determine the exact values of rpot(Kn,Kt-k)for 1≤k≤2. 展开更多
关键词 graphic sequence potential-Ramsey number
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