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比值-特征主成分混合分析提取金矿蚀变信息——以赣南遂川地区为例 被引量:5
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作者 刘志杰 韩先菊 刘荫椿 《黄金地质》 1998年第1期74-77,共4页
在分析与金矿成矿有关的两类蚀变岩的TM波谱特征的基础上,以赣南遂川地区为实验区,利用比值-特征主成分混合分析进行了金矿蚀变岩信息提取,为找矿预测和野外工作指明了方向。
关键词 金矿床 蚀变信息 主成分混合分析 比值-特征
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Prognostic value of fibrinogen and D-dimer-fibrinogen ratio in resectable gastrointestinal stromal tumors 被引量:20
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作者 Hua-Xia Cai Xu-Qi Li Shu-Feng Wang 《World Journal of Gastroenterology》 SCIE CAS 2018年第44期5046-5056,共11页
AIM To investigate the prognostic value of preoperative fbri-nogen concentration (FIB) and D-dimer-fibrinogen ratio (DFR) in gastrointestinal stromal tumors (GISTs).METHODS The purpose of this study was to retro... AIM To investigate the prognostic value of preoperative fbri-nogen concentration (FIB) and D-dimer-fibrinogen ratio (DFR) in gastrointestinal stromal tumors (GISTs).METHODS The purpose of this study was to retrospectively ana-lyze 170 patients with GISTs who were admitted to our hospital from January 2010 to December 2015. The op-timal cutoff values of related parameters were estimated by receiver operating characteristic (ROC) curve analysis. The recurrence free survival (RFS) rate was evaluated using Kaplan-Meier curves. Univariate analysis and multivariate Cox regression models were used to analyze the prognostic factors of GISTs. The relationship between the FIB, D-dimer, DFR, platelet count (PLT), and the clinicopathological features of GISTs was described by the chi-square test or nonparametric rank sum test (Mann-Whitney test).RESULTS In ROC analysis, the optimal cutoff values of FIB, D-dimer, DFR, and PLT were 3.24 g/L, 1.24 mg/L, 0.354, and 197.5 (× 109/L), respectively. Univariate analysis and the Kaplan-Meier survival curve showed that FIB, D-dimer, DFR, PLT,National Institutes of Health (NIH) risk category, tumor size, tumor location, and mitotic index were signifcantly relevant to the 3-year and 5-year survival rate of patients ( P 〈 0.05). Cox multivariate regression analysis illustrated that FIB (RR: 0.108, 95%CI: 0.031-0.373), DFR (RR: 0.319, 95%CI: 0.131-0.777), and NIH risk category ( RR: 0.166, 95%CI: 0.047-0.589) were independent prognostic factors of the RFS rate ( P 〈 0. 05). Moreover, FIB, D-dimer, DFR, and PLT were correlated with the clinical features of GISTs.CONCLUSIONFIB, D-dimer, DFR, and PLT are all related to the prognosis of GISTs. Moreover, FIB and DFR may be independent risk factors for predicting the prognosis of resectable GISTs. 展开更多
关键词 D-DIMER D-dimer-fbrinogen ratio PROGNOSIS FIBRINOGEN Gastrointestinal stromal tumor
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The Preliminary Analysis of the Characteristics of Geomagnetic Harmonic Wave Amplitude Ratios before the Gaoyou-Baoying MS4.9 Earthquake
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作者 Jiang Yanlin Yuan Guiping +2 位作者 Li Hongyu Tang Tingmei Zhao Weihong 《Earthquake Research in China》 CSCD 2016年第4期578-583,共6页
In this paper,the Gaoyou-Baoying M_S4.9 earthquake was analyzed by the geomagnetic harmonic wave amplitude ratios method. The earthquake was an isolated seismic event,before and after which there were no other earthqu... In this paper,the Gaoyou-Baoying M_S4.9 earthquake was analyzed by the geomagnetic harmonic wave amplitude ratios method. The earthquake was an isolated seismic event,before and after which there were no other earthquakes occurred in this region. The dense distribution of geomagnetic observataries provided an advantage condition for the analysis of characteristics of the geomagnetic harmonic amplitude ratios. The analysis results verify the former knowledge of anomaly characteristics of the geomagnetic harmonic amplitude ratio,that is,the anomalous characteristics of the earthquake mostly appeared during the decline-turning-recovery rising process. The results also show that the change of the anomalies was asynchronous at the observatories close to the epicenter, namely, the anomalous characteristics were different between the H and the D components,as well as between the long and short periods. 展开更多
关键词 GEOMAGNETIC Anomaly Harmonic wave Gaoyou-Baoying Ms4.9 earthquake
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Hamiltonian s-properties and(Laplacian)Spreads of k-connected Graphs
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作者 CHEN Hongzhang LI Jianxi SHIU Wai Chee 《数学进展》 CSCD 北大核心 2024年第6期1181-1187,共7页
A graph G possesses Hamiltonian s-properties when G is Hamilton-connected if s=1,Hamiltonian if s=0,and traceable if s=-1.Let S_A(G)=λ_n(G)-λ_1(G)and S_L(G)=μ_n(G)-μ_2(G)be the spread and the Laplacian spread of G... A graph G possesses Hamiltonian s-properties when G is Hamilton-connected if s=1,Hamiltonian if s=0,and traceable if s=-1.Let S_A(G)=λ_n(G)-λ_1(G)and S_L(G)=μ_n(G)-μ_2(G)be the spread and the Laplacian spread of G,respectively,whereλ_n(G)andλ_1(G)are the largest and smallest eigenvalues of G,andμ_n(G)andμ_2(G)are the largest and second smallest Laplacian eigenvalues of G,respectively.In this paper,we shall present two sufficient conditions involving S_A(G)and S_L(G)for a k-connected graph to possess Hamiltonian s-properties,respectively.We also derive a sufficient condition on the Laplacian eigenratio■for a k-connected graph to possess Hamiltonian s-properties. 展开更多
关键词 (Laplacian)spread Hamiltonian s-property Laplacian eigenratio k-connected graph
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Influence of heat treatment conditions on bending characteristics of 6063 aluminum alloy sheets 被引量:6
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作者 Zhi-wen LIU Luo-xing LI +3 位作者 Jie YI Shi-kang LI Zhen-hu WANG Guan WANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第7期1498-1506,共9页
Bending deformation behaviors of solution treated(ST),natural aged(NA)and T6tempered6063aluminum alloy sheetswere studied by three-point bending tests.The changes of bending force,interior angle,bending radius and she... Bending deformation behaviors of solution treated(ST),natural aged(NA)and T6tempered6063aluminum alloy sheetswere studied by three-point bending tests.The changes of bending force,interior angle,bending radius and sheet thickness in thefillet region were analyzed by experimental measurements and numerical simulations.The results showed that the bendingcharacteristics were strongly dependent on the heat treatment conditions.The T6alloy sheets were bent more sharply and localplastic deformation occurred severely in the fillet region.However,the ST and NA alloy sheets exhibited relatively uniform bendingdeformation and large bending radius.The bending force of T6alloy was the highest,followed by the NA alloy and that of the STalloy was minimum.After unloading,as compared with the ST and NA alloys,the springback of T6alloys was markedly larger.Theaging time showed a positive sensitivity on the springback and non-uniform bending deformability.The bending characteristics areattributed to the combined effects of yield strength,yield ratio and coefficient of neutral layer. 展开更多
关键词 6063 aluminum alloy three-point bending heat treatment conditions bending characteristic yield ratio simulation
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Application of Bifurcation Analysis on Active Distribution Systems
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作者 Mohamed Mahmoud Aly Ahmed Bedawy Mamdouh Abdel-Akher 《Journal of Energy and Power Engineering》 2012年第12期1994-2000,共7页
This paper presents the application of bifurcation method on the steady state three-phase load-flow Jacobian method to study the voltage stability of unbalanced distribution systems. The eigenvalue analysis is used to... This paper presents the application of bifurcation method on the steady state three-phase load-flow Jacobian method to study the voltage stability of unbalanced distribution systems. The eigenvalue analysis is used to study distribution system behavior under different operating conditions. Two-bus connected by asymmetrical line is used as the study system. The effects of both unbalance and extreme loading conditions are investigated. Also, the impact of distributed energy resources is studied. Different case studies and loading scenarios are presented to trace the eigenvalues of the Jacobian matrix. The results exhibit the existence of a new bifurcation point which may not be related to the voltage stability. 展开更多
关键词 BIFURCATION voltage stability EIGENVALUES saddle node bifurcation DERs (distributed energy resources).
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Gap results for compact quasi-Einstein metrics
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作者 Linfeng Wang 《Science China Mathematics》 SCIE CSCD 2018年第5期943-954,共12页
In this paper, we work on compact quasi-Einstein metrics and prove several gap results. In the first part, we get a gap estimate for the first nonzero eigenvalue of the weighted Laplacian, by establishing a comparison... In this paper, we work on compact quasi-Einstein metrics and prove several gap results. In the first part, we get a gap estimate for the first nonzero eigenvalue of the weighted Laplacian, by establishing a comparison theorem for the weighted heat kernel. In the second part, we establish two gap results for the Ricci curvature and the scalar curvature, based on which some rigid properties can be derived. 展开更多
关键词 quasi-Einstein metric heat kernel eigenvalue diameter Ricci curvature scalar curvature gap result
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A NEW LAPLACIAN COMPRISON THEOREM AND THE ESTIMATE OF EIGENVALUES 被引量:1
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作者 DING QING 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 1994年第1期35-42,共8页
This paper establishes a new Laplacian comparison theorem which is specially useful tothe mathelds of nonpositive curvature. It leads naturally to the corresponding heat kernelcomparison and eigenvalue comparison theo... This paper establishes a new Laplacian comparison theorem which is specially useful tothe mathelds of nonpositive curvature. It leads naturally to the corresponding heat kernelcomparison and eigenvalue comparison theorems. Furthermore, a lower estimate of L2-spectrumof an n-dimensional non-compact complete Cartan-Hadamard manifold is given by (n-1)k/4,provided its mRicci curvature -(n -1)k (k= const. 0). 展开更多
关键词 Laplacian operator Comparison theorem Heat kernel Eigenvalue.
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Eigenvalue Comparison Theorems on Finsler Manifolds 被引量:1
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作者 Songting YIN Qun HE 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2015年第1期31-44,共14页
Cheng-type inequality, Cheeger-type inequality and Faber-Krahn-type inequality are generalized to Finsler manifolds. For a compact Finsler manifold with the weighted Ricci curvature bounded from below by a negative co... Cheng-type inequality, Cheeger-type inequality and Faber-Krahn-type inequality are generalized to Finsler manifolds. For a compact Finsler manifold with the weighted Ricci curvature bounded from below by a negative constant, Li-Yau's estimation of the first eigenvalue is also given. 展开更多
关键词 The first eigenvalue Finsler-Laplacian Ricci curvature S-CURVATURE
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Comparative analysis of the characteristics of global seismic wave propagation excited by the M_w 9.0 Tohoku earthquake using numerical simulation 被引量:4
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作者 YAN ZhenZhen ZHANG Huai +1 位作者 FAN XiangTao DU XiaoPing 《Science China Earth Sciences》 SCIE EI CAS 2014年第7期1626-1636,共11页
Giant earthquakes generate rich signals that can be used to explore the characteristics of the hierarchical structure of the Earth’s interior associated with the eigenfrequencies of the Earth.We employ the spectral e... Giant earthquakes generate rich signals that can be used to explore the characteristics of the hierarchical structure of the Earth’s interior associated with the eigenfrequencies of the Earth.We employ the spectral element method,incorporated with large-scale parallel computing technology,to investigate the characteristics of global seismic wave propagation excited by the2011 Mw9.0 Tohoku earthquake.The transversely isotropic PREM model is employed as a prototype of our numerical global Earth model.Topographic data and the effect of the oceans are taken into consideration.Wave propagation processes are simulated by solving three-dimensional elastic wave governing equations with the seismic moment tensor obtained from the Global Centroid Moment Tensor Catalog.Three-dimensional visualization of our computing results displays the nature of the global seismic wave propagation.Comparative analysis of our calculations with observations obtained from the Incorporated Research Institutions for Seismology demonstrates the reliability and feasibility of our numerical results.We compare synthetic seismograms with incorporated and unincorporated ocean models.First results show that the oceans have obvious effects on the characteristics of seismic wave propagation.The peak displacement and peak velocity of P waves become relatively small under the effect of the ocean.However,the effect of the ocean on S-waves is complex.The displacement and velocity of S waves decrease rapidly over time using an unincorporated ocean model.Therefore,the effects of the ocean should be incorporated when undertaking quantitative earthquake hazard assessments on coastal areas.In addition,we undertake comparative analysis on the characteristics of the Earth’s oscillation excited by the 2004 Sumatra-Andaman,2008 Wenchuan,and 2011Tohoku earthquakes that incorporate the effect of the Earth’s gravitational potential.A comparison of the amplitude spectra of the numerical records indicates that energy released by the three big earthquakes is different.Our comparative analysis realizes that the computing results can accurately reproduce some eigenfrequencies of the Earth,such as toroidal modes 0T2 to 0T13and spheroidal modes 0S7 to 0S31.These results demonstrate that numerical simulations can be successfully used to investigate the Earth’s oscillations.We propose that numerical simulations can be used as one of the major tools to further reveal how the Earth’s lateral heterogeneities affect the Earth’s oscillations. 展开更多
关键词 Mw9.0 Tohoku earthquake Sea of Japan numerical simulation global seismic wave propagation Earth's oscillations
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Maximization of the sum of the trace ratio on the Stiefel manifold, I: Theory 被引量:1
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作者 ZHANG LeiHong LI RenCang 《Science China Mathematics》 SCIE 2014年第12期2495-2508,共14页
We are concerned with the maximization of tr(V T AV)/tr(V T BV)+tr(V T CV) over the Stiefel manifold {V ∈ R m×l | V T V = Il} (l 〈 m), where B is a given symmetric and positive definite matrix, A and... We are concerned with the maximization of tr(V T AV)/tr(V T BV)+tr(V T CV) over the Stiefel manifold {V ∈ R m×l | V T V = Il} (l 〈 m), where B is a given symmetric and positive definite matrix, A and C are symmetric matrices, and tr(. ) is the trace of a square matrix. This is a subspace version of the maximization problem studied in Zhang (2013), which arises from real-world applications in, for example, the downlink of a multi-user MIMO system and the sparse Fisher discriminant analysis in pattern recognition. We establish necessary conditions for both the local and global maximizers and connect the problem with a nonlinear extreme eigenvalue problem. The necessary condition for the global maximizers offers deep insights into the problem, on the one hand, and, on the other hand, naturally leads to a self-consistent-field (SCF) iteration to be presented and analyzed in detail in Part II of this paper. 展开更多
关键词 trace ratio Rayleigh quotient Stiefel manifold nonlinear eigenvalue problem optimality condition EIGENSPACE
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