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On the Distribution Property of LehmerDH Number
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作者 GAOLi 《Chinese Quarterly Journal of Mathematics》 CSCD 2004年第1期75-78,共4页
This paper is to study the distribution property of Lehmer DH number by use the estimation of general Kloostermann sum and the estimation of trigonometric sum.
关键词 Lehmer DH number primitive root distribution property Kloostermann sum asymptotic formula
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Some dynamical property of the Tsallis distribution from a Fokker-Planck equation 被引量:1
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作者 杜九林 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第4期81-84,共4页
This paper studies the possible dynamical property of the Tsallis distribution from a Fokker--Planck equation. For the Langevin dynamical system with an {arbitrary} potential function, Markovian friction and Gaussian ... This paper studies the possible dynamical property of the Tsallis distribution from a Fokker--Planck equation. For the Langevin dynamical system with an {arbitrary} potential function, Markovian friction and Gaussian white noise, it shows that the current form of Tsallis distribution cannot describe any nonequilibrium dynamics of the system, and it only stands for a simple isothermal situation of the system governed by a potential field. So the form of Tsallis distribution and many existing applications using the Tsallis distribution need to be reconsidered. 展开更多
关键词 Tsallis distribution dynamical property Fokker--Planck equation
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The Relationship between Bulk Property and Property Distribution in Thin-Wall Injection Molded PP at Different Molecular Weight and Molecular Weight Distribution
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作者 Keisuke Maeda Koji Yamada +2 位作者 Kazushi Yamada Masaya Kotaki Hiroyuki Nishimura 《Advances in Materials Physics and Chemistry》 2016年第1期1-8,共8页
Thin-wall injection molded parts have been paid much attention to the lightweight saving from viewpoints of natural resources saving. In the injection molding, skin-core structure can be found in the parts. This skin-... Thin-wall injection molded parts have been paid much attention to the lightweight saving from viewpoints of natural resources saving. In the injection molding, skin-core structure can be found in the parts. This skin-core structure affects the property of completed injection molding parts (bulk property) even if in thin-wall injection molding. However, there is a few research about the relationship between bulk property and internal property distribution in the injection molding specimen. In this study, thin-wall injection molded parts of polypropylene (PP) were prepared by 4 different molecular weight and molecular weight distribution to reveal the relationship between bulk property and property distribution. These characteristics were investigated by using tensile test, fracture toughness characterized by Essential Work of Fracture (EWF) method for bulk property and film tensile test by sliced sample for tensile property distribution. The property distribution test results revealed that the highly bulk property sample had thicker highly mechanical property layer on its surface. 展开更多
关键词 Molecular Weight Molecular Weight distribution Fracture Toughness property distribution Thin-Wall Injection Molding
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Toward Improved Accuracy in Quasi-Static Elastography Using Deep Learning
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作者 Yue Mei Jianwei Deng +4 位作者 Dongmei Zhao Changjiang Xiao Tianhang Wang Li Dong Xuefeng Zhu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第4期911-935,共25页
Elastography is a non-invasive medical imaging technique to map the spatial variation of elastic properties of soft tissues.The quality of reconstruction results in elastography is highly sensitive to the noise induce... Elastography is a non-invasive medical imaging technique to map the spatial variation of elastic properties of soft tissues.The quality of reconstruction results in elastography is highly sensitive to the noise induced by imaging measurements and processing.To address this issue,we propose a deep learning(DL)model based on conditional Generative Adversarial Networks(cGANs)to improve the quality of nonhomogeneous shear modulus reconstruction.To train this model,we generated a synthetic displacement field with finite element simulation under known nonhomogeneous shear modulus distribution.Both the simulated and experimental displacement fields are used to validate the proposed method.The reconstructed results demonstrate that the DL model with synthetic training data is able to improve the quality of the reconstruction compared with the well-established optimization method.Moreover,we emphasize that our DL model is only trained on synthetic data.This might provide a way to alleviate the challenge of obtaining clinical or experimental data in elastography.Overall,this work addresses several fatal issues in applying the DL technique into elastography,and the proposed method has shown great potential in improving the accuracy of the disease diagnosis in clinical medicine. 展开更多
关键词 Nonhomogeneous elastic property distribution reconstruction deep learning finite element method inverse problem ELASTOGRAPHY conditional generative adversarial network
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Quantum Chemistry Investigation into the Distribution Properties of 2-Formamido-phenylacrylates in n-Octanol/Water System 被引量:1
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作者 赵惠明 张幸川 +1 位作者 余菁 王遵尧 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2006年第3期265-270,共6页
Molecular property parameters of 16 2-formamido-phenylacryiates were calculated with Hartree-Fock and DFT methods at six different levels. Using the molecular property parameters and dissolvability as theoretical desc... Molecular property parameters of 16 2-formamido-phenylacryiates were calculated with Hartree-Fock and DFT methods at six different levels. Using the molecular property parameters and dissolvability as theoretical descriptors, two quantitative correlation equations that could be used to predict lgKow were developed based on experimental lgKow data of 11 2-formamido-phenylacrylates. A three-parameter correlation equation posing the ability of predicting -lgSw value was computed at B3LYP/6-311G** level. The -lgSw values of five compounds that we have pre-designed were anticipated with the above equation, upon which lgKow were further calculated. The relativity (r^2≥0.94, q^2〉0.91, SD≤0.083) and prediction ability of obtained correlation equations in this work are more advantageous than those based on solvatochromism parameters. 展开更多
关键词 2-formamido-phenylacrylates linear solvation energy theory HARTREE-FOCK DFT method QSAR distribution properties
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Reliability analysis of extended generalized inverted exponential distribution with applications
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作者 Arwa M.Alshangiti M.Kayid M.Almulhim 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2016年第2期484-492,共9页
A general version of the inverted exponential distribution is introduced, studied and analyzed. This generalization depends on the method of Marshall-Olkin to extend a family of distributions. Some statistical and rel... A general version of the inverted exponential distribution is introduced, studied and analyzed. This generalization depends on the method of Marshall-Olkin to extend a family of distributions. Some statistical and reliability properties of this family are studied. In addition, numerical estimation of the maximum likelihood estimate(MLE) parameters are discussed in details. As an application, some real data sets are analyzed and it is observed that the presented family provides a better fit than some other known distributions. 展开更多
关键词 inverted exponential distribution reliability properties statistical properties maximum likelihood estimates applications
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Effects of thermal transport properties on temperature distribution within silicon wafer
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作者 王爱华 牛义红 +1 位作者 陈铁军 P.F.HSU 《Journal of Central South University》 SCIE EI CAS 2014年第4期1402-1410,共9页
A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface... A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface. It is found that the increased conductivities in both doped and undoped regions help reduce the temperature difference across the wafer surface. However, the doped layer conductivity has little effect on the overall temperature distribution and difference. The temperature level and difference on the top surface drop suddenly when absorption coefficient changes from 104 to 103 m-1. When the absorption coefficient is less or equal to 103 m-1, the temperature level and difference do not change much. The emissivity has the dominant effect on the top surface temperature level and difference. Higher surface emissivity can easily increase the temperature level of the wafer surface. After using the improved property data, the overall temperature level reduces by about 200 K from the basis case. The results will help improve the current understanding of the energy transport in the rapid thermal processing and the wafer temperature monitor and control level. 展开更多
关键词 silicon wafer thermal transport properties temperature distribution radiation heat transfer
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Effect of Nickel Distributions Embedded in Amorphous Carbon Films on Transport Properties
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作者 Vali Dalouji Dariush Mehrparvar +1 位作者 Shahram Solaymani Sahar Rezaee 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第2期61-65,共5页
Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78,3.21,3.92 and 4.64%.The conductivity data in the temperature range o... Electrical properties of C/Ni films are studied using four mosaic targets made of pure graphite and stripes of nickel with the surface areas of 1.78,3.21,3.92 and 4.64%.The conductivity data in the temperature range of400-500 K shows the extended state conduction.The conductivity data in the temperature range of 150-300 K shows the multi-phonon hopping conduction.The Berthelot-type conduction dominates in the temperature range of 50-150 K.The conductivity of the films in the temperature range about 〈 50 K is described in terms of variable-range hopping conduction.In low temperatures,the localized density of state around Fermi level(F)for the film deposition with 3.92% nickel has a maximum value of about 56.2×10^(17)cm^(-3)eV^(-1) with the minimum average hopping distance of about 3.43 × 10^(-6) cm. 展开更多
关键词 NI Effect of Nickel distributions Embedded in Amorphous Carbon Films on Transport Properties
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A STUDY ON THE INTERACTION BETWEEN CH_3OH AND H_2CO MOLECULES IN TERMS OF THE PROPERTIES OF CHARGE DENSITY DISTRIBUTIONS
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作者 Wei Liang CAO Jing Chang ZHANG Beijing Institute of Chemical Technology Beijing China 100029Xiao Yuan FU Beijing Normal University Beijing China 100875 《Chinese Chemical Letters》 SCIE CAS CSCD 1991年第7期571-574,共4页
Two possible complexes formed by the interaction of CH_3OH and H_2CO,one hydrogen-bonded (Ⅰ)and one donor-acceptor complex(Ⅱ),have been reported in the previous paper.Based on the ab initio 6-31G basis set calculati... Two possible complexes formed by the interaction of CH_3OH and H_2CO,one hydrogen-bonded (Ⅰ)and one donor-acceptor complex(Ⅱ),have been reported in the previous paper.Based on the ab initio 6-31G basis set calculations,the properties of the charge density for the complexeshave been analyzed using the theory of atoms in molecules.The nature of the complex formation has been discussed in terms of the properties of the charge density distributions. 展开更多
关键词 OH A STUDY ON THE INTERACTION BETWEEN CH3OH AND H2CO MOLECULES IN TERMS OF THE PROPERTIES OF CHARGE DENSITY distributionS CH CO
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Numerical simulation study of ionization characteristics of argon dielectric barrier discharge
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作者 刘桂铭 陈雷 +1 位作者 赵智博 宋鹏 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第12期441-448,共8页
In order to better analyze the characteristics of particle distribution and its influencing factors in the ionized space during the process of coaxial dielectric barrier discharge,a self-designed two-dimensional axisy... In order to better analyze the characteristics of particle distribution and its influencing factors in the ionized space during the process of coaxial dielectric barrier discharge,a self-designed two-dimensional axisymmetric structure exciter was used to carry out optical diagnosis,with the electron temperature calculated through Gaussian fitting.A plasma model was applied to conduct research on the discharge process through numerical simulation,with the changes in electron density and electron temperature were analyzed by using different discharge parameters.The research results show that with an increase in discharge voltage,pressure inside the reactor and relative permittivity,the discharge process is promoted.In addition,a rise in current density leads to an increase in the number of charged particles on the surface of the medium during the discharge process,while a rise in discharge intensity causes an increase in the electron density.Electron temperature decreases due to the increased loss of collision energy between particles.These results were confirmed by comparing experimental data with simulation results. 展开更多
关键词 dielectric barrier discharge particle distribution properties electron density electron temperature
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Microstructure and Properties of Cement Foams Prepared by Magnesium Oxychloride Cement 被引量:6
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作者 王发洲 YANG Lu +1 位作者 GUAN Lingyue HU Shuguang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第2期331-337,共7页
Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams(MOCF) with various MgO powders and water mixture ratios were studied. Their infl uen... Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams(MOCF) with various MgO powders and water mixture ratios were studied. Their infl uences on compressive strength, water absorption and resistance of MOCF were also discussed in detail. The experimental results indicated that moderate and slight excess MgO powders(MgO/MgCl2 molar ratios from 5.1 to 7) were beneficial to the formation of excellent microstructure of MOCF, but increasing water contents(H2O/MgO mass ratios from 0.9 to 1.29) might result in opposite conclusions. The microstructure of MOCF produced with moderate and slight excess MgO powders could enhance the compressive strength, while serious excess MgO powders addition(MgO/MgCl2 molar ratios = 9) would destroy the cell wall structures, and therefore decrease the strength of the system. Although MOCF produced with excess MgO powders could decrease the water absorption, its softening coefficient was lower than that of the material produced with moderate MgO powders. This might be due to the instability of phase 5, the volume expansion and cracking of cell walls as immersed the sample into water. 展开更多
关键词 magnesium oxychloride cement foams pore size distribution weibull distribution function cell walls phase compositions properties
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On the generalized Cauchy function and new Conjecture on its exterior singularities 被引量:1
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作者 Theodore Yaotsu Wu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2011年第2期135-151,共17页
This article studies on Cauchy’s function f (z) and its integral, (2πi)J[ f (z)] ≡ ■C f (t)dt/(t z) taken along a closed simple contour C, in regard to their comprehensive properties over the entire z =... This article studies on Cauchy’s function f (z) and its integral, (2πi)J[ f (z)] ≡ ■C f (t)dt/(t z) taken along a closed simple contour C, in regard to their comprehensive properties over the entire z = x + iy plane consisted of the simply connected open domain D + bounded by C and the open domain D outside C. (1) With f (z) assumed to be C n (n ∞-times continuously differentiable) z ∈ D + and in a neighborhood of C, f (z) and its derivatives f (n) (z) are proved uniformly continuous in the closed domain D + = [D + + C]. (2) Cauchy’s integral formulas and their derivatives z ∈ D + (or z ∈ D ) are proved to converge uniformly in D + (or in D = [D +C]), respectively, thereby rendering the integral formulas valid over the entire z-plane. (3) The same claims (as for f (z) and J[ f (z)]) are shown extended to hold for the complement function F(z), defined to be C n z ∈ D and about C. (4) The uniform convergence theorems for f (z) and F(z) shown for arbitrary contour C are adapted to find special domains in the upper or lower half z-planes and those inside and outside the unit circle |z| = 1 such that the four general- ized Hilbert-type integral transforms are proved. (5) Further, the singularity distribution of f (z) in D is elucidated by considering the direct problem exemplified with several typ- ical singularities prescribed in D . (6) A comparative study is made between generalized integral formulas and Plemelj’s formulas on their differing basic properties. (7) Physical sig- nificances of these formulas are illustrated with applicationsto nonlinear airfoil theory. (8) Finally, an unsolved inverse problem to determine all the singularities of Cauchy function f (z) in domain D , based on the continuous numerical value of f (z) z ∈ D + = [D + + C], is presented for resolution as a conjecture. 展开更多
关键词 Uniform continuity of Cauchy’s function · Uni- form convergence of Cauchy’s integral formula · Generalized Hilbert-type integral transforms · Functional properties and singularity distributions
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Plate reinforced square hollow section X-joints subjected to in-plane moment 被引量:2
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作者 陈希湘 陈誉 陈栋芬 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期1002-1015,共14页
The static test of 13 square hollow section(SHS) X-joints with different β and different types of plate reinforcement under in-plane moment in brace was carried out. Experimental test schemes, failure modes of specim... The static test of 13 square hollow section(SHS) X-joints with different β and different types of plate reinforcement under in-plane moment in brace was carried out. Experimental test schemes, failure modes of specimens, moment-vertical displacement curves, moment-deformation of the chord, and strain strength distribution curves were presented. The effect of β and plate reinforcement types on in-plane flexural property of SHS X-joints was studied. Results show that punching shear of chord face disappears, brace material fracture appears and concave and convex deformation of chord decrease when either collar plates or doubler plates were welded on chord face. Moment-vertical displacement curves of all specimens have obvious elastic, elastic-plastic and plastic stages. As β increases, the in-plane flexural ultimate capacity and initial stiffness of joints of the same plate reinforcement type increase, but ductility of joints decreases. With the same β, the in-plane flexural initial stiffness and ultimate capacity of doubler plate reinforced joints, collar plate reinforced joints, and unreinforced joints decrease progressively. Thickness of reinforcement plate has no obvious effect on in-plane flexural initial stiffness and ultimate capacity of joints. As thickness of reinforcement plate increases, the ductility of reinforced X-joints decreases. The concave and convex deformation of every specimen has good symmetry;as β increases, the yield and ultimate deformation of chord decrease. 展开更多
关键词 failure analysis square hollow section(SHS) X-joints plate reinforcement types in-plane flexural property ultimate capacity initial stiffness strain strength distribution ductility
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Covariance Estimation Using High-Frequency Data: An Analysis of Nord Pool Electricity Forward Data
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作者 faculty of economics and organization science,lillehammer university college,lillehammer no-2624,norway 《Journal of Energy and Power Engineering》 2012年第4期570-579,共10页
The modeling of volatility and correlation is important in order to calculate hedge ratios, value at risk estimates, CAPM (Capital Asset Pricing Model betas), derivate pricing and risk management in general. Recent ... The modeling of volatility and correlation is important in order to calculate hedge ratios, value at risk estimates, CAPM (Capital Asset Pricing Model betas), derivate pricing and risk management in general. Recent access to intra-daily high-frequency data for two of the most liquid contracts at the Nord Pool exchange has made it possible to apply new and promising methods for analyzing volatility and correlation. The concepts of realized volatility and realized correlation are applied, and this study statistically describes the distribution (both distributional properties and temporal dependencies) of electricity forward data from 2005 to 2009. The main findings show that the logarithmic realized volatility is approximately normally distributed, while realized correlation seems not to be. Further, realized volatility and realized correlation have a long-memory feature. There also seems to be a high correlation between realized correlation and volatilities and positive relations between trading volume and realized volatility and between trading volume and realized correlation. These results are to a large extent consistent with earlier studies of stylized facts of other financial and commodity markets. 展开更多
关键词 Realized volatility and correlation high-frequency data distribution properties temporal dependence Nord Pool forward data.
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Vertical distribution of aerosol optical properties based on aircraft measurements over the Loess Plateau in China 被引量:6
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作者 Junxia Li Xingang Liu +9 位作者 Liang Yuan Yan Yin Zhanqing Li Peiren Li Gang Ren Lijun Jin Runjun Li Zipeng Dong Yiyu Li Junmei Yang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2015年第8期44-56,共13页
Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four ... Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients(σsc), absorption coefficients(σab),Angstr?m exponent(α), single scattering albedo(ω), backscattering ratio(βsc), aerosol mass scattering proficiency(Q sc) and aerosol surface scattering proficiency(Q sc′) were obtained. The mean statistical values of σsc were 77.45 Mm-1(at 450 nm), 50.72 Mm-1(at 550 nm), and32.02 Mm-1(at 700 nm). The mean value of σab was 7.62 Mm-1(at 550 nm). The mean values ofα, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters(ED) of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Q sc and Q sc′ showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Q sc, Q sc′, σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions. 展开更多
关键词 Vertical distribution Optical properties Aircraft measurements The Loess Plateau
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On the Decomposition Theorems for C^(*)-Algebras
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作者 Chunlan JIANG Liangqing LI Kun WANG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2020年第6期829-860,共32页
Elliott dimension drop interval algebra is an important class among all C^*-algebras in the classification theory.Especially,they are building stones of AHD algebra and the latter contains all AH algebras with the ide... Elliott dimension drop interval algebra is an important class among all C^*-algebras in the classification theory.Especially,they are building stones of AHD algebra and the latter contains all AH algebras with the ideal property of no dimension growth.In this paper,the authors will show two decomposition theorems related to the Elliott dimension drop interval algebra.Their results are key steps in classifying all AH algebras with the ideal property of no dimension growth. 展开更多
关键词 C^(*)-algebra Elliott dimension drop interval algebra Decomposition theorem Spectral distribution property
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Quality Assessment of Transcriptome Data Using Intrinsic Statistical Properties 被引量:2
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作者 Guillaume Brysbaert Franois-Xavier Pellay +1 位作者 Sebastian Noth Arndt Benecke 《Genomics, Proteomics & Bioinformatics》 SCIE CAS CSCD 2010年第1期57-71,共15页
In view of potential application to biomedical diagnosis, tight transcriptome data quality control is compulsory. Usually, quality control is achieved using labeling and hybridization controls added at different stage... In view of potential application to biomedical diagnosis, tight transcriptome data quality control is compulsory. Usually, quality control is achieved using labeling and hybridization controls added at different stages throughout the processing of the biologic RNA samples. These control measures, however, only reflect the performance of the individual technical manipulations during the entire process and have no bearing as to the continued integrity of the RNA sample itself. Here we demonstrate that intrinsic statistical properties of the resulting transcriptome data signal and signal-variance distributions and their invariance can be identified independently of the animal species studied and the labeling protocol used. From these invariant properties we have developed a data model, the pa- rameters of which can be estimatei:l from individual experiments and used to compute relative quality measures based on similarity with large reference datasets. These quality measures add supplementary, non-redundant in- formation to standard quality control estimates based on spike-in and hybridization controls, and are exploitable in data analysis. A software application for analyzing datasets as well as a reference dataset for AB 1700 arrays are provided. They should allow AB 1700 users to easily integrate this method into their analysis pipeline, and might instigate similar developments for other transcriptome platforms. 展开更多
关键词 TRANSCRIPTOME MICROARRAY quality control distribution properties STATISTICS SOFTWARE
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Comparative study on local and global mechanical properties of bobbin tool and conventional friction stir welded 7085-T7452 aluminum thick plate 被引量:10
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作者 Weifeng Xu Yuxuan Luo +1 位作者 Wei Zhang Mingwang Fu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第1期173-184,共12页
7085-T7452 plates with a thickness of 12 mm were welded by conventional single side and bobbin tool friction stir welding (SS-FSW and BB-FSW, respectively) at different welding parameters. The temperature distributi... 7085-T7452 plates with a thickness of 12 mm were welded by conventional single side and bobbin tool friction stir welding (SS-FSW and BB-FSW, respectively) at different welding parameters. The temperature distribution, microstructure evolution and mechanical properties of joints along the thickness direction were investigated, and digital image correlation (DIC) was utilized to evaluate quantitatively the deformation of different zones during tensile tests. The results indicated that heat-affected zone (HAZ), the local softening region, was responsible for the early plastic deformation and also the fracture location for SS-FSW samples, while a rapid fracture was observed in weld nugget zone (WNZ) before yield behavior for all BB-FSW specimens. The ultimate tensile strength (UTS) of SS-FSW joints presented the highest value of 410 MPa, 82% of the base material, at a rotational speed of 300 rpm and welding speed of 60 mm/min, much higher than that of BB-FSW joints, with a joint efficiency of only 47%. This should be attributed to the Lazy S defect produced by a larger extent of heat input during the BB-FSW process, The whole joint exhibited a much higher elongation than the slices. Scanning electron microscopic (SEM) analysis of the fracture morphologies showed that joints failed through ductile fracture for SS-FSW and brittle fracture for BB-FSW. 展开更多
关键词 Aluminum alloy Friction stir welding Bobbin tool Temperature distribution Microstructure Mechanical properties
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Electrical transport and current properties of rare-earth dysprosium Schottky electrode on p-type GaN at various annealing temperatures 被引量:1
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作者 G.Nagaraju K.Ravindranatha Reddy V.Rajagopal Reddy 《Journal of Semiconductors》 EI CAS CSCD 2017年第11期39-47,共9页
The electrical and current transport properties of rapidly annealed Dy/p-GaN SBD are probed by I-V and C-V techniques. The estimated barrier heights(BH) of as-deposited and 200 ℃ annealed SBDs are 0.80 eV(I-V)/0.... The electrical and current transport properties of rapidly annealed Dy/p-GaN SBD are probed by I-V and C-V techniques. The estimated barrier heights(BH) of as-deposited and 200 ℃ annealed SBDs are 0.80 eV(I-V)/0.93 eV(C-V) and 0.87 eV(I-V)/1.03 eV(C-V). However, the BH rises to 0.99 eV(I-V)/1.18 eV(C-V)and then slightly deceases to 0.92 eV(I-V)/1.03 eV(C-V) after annealing at 300 ℃ and 400 ℃. The utmost BH is attained after annealing at 300 ℃ and thus the optimum annealing for SBD is 300 ℃. By applying Cheung's functions, the series resistance of the SBD is estimated. The BHs estimated by I-V, Cheung's and ΨS-V plot are closely matched; hence the techniques used here are consistency and validity. The interface state density of the as-deposited and annealed contacts are calculated and we found that the NSS decreases up to 300 ℃ annealing and then slightly increases after annealing at 400 ℃. Analysis indicates that ohmic and space charge limited conduction mechanisms are found at low and higher voltages in forward-bias irrespective of annealing temperatures. Our experimental results demonstrate that the Poole-Frenkel emission is leading under the reverse bias of Dy/p-GaN SBD at all annealing temperatures. 展开更多
关键词 p-GaN rare-earth Dy Schottky contacts annealing effects electrical properties energy distribution profiles carrier transport mechanism
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Improving Joint Features and Mechanical Properties of Pinless Fiction Stir Welding of Alcald 2A12-T4 Aluminum Alloy 被引量:7
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作者 Zhenlei Liu Hutao Cui +2 位作者 Shude Ji Minqiang Xu Xiangchen Meng 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2016年第12期1372-1377,共6页
As a new solid state welding,pinless friction stir welding(PFSW) can be used to join thin-wall structures.In this study,four new pinless tools with different groove distributions were designed and manufactured in or... As a new solid state welding,pinless friction stir welding(PFSW) can be used to join thin-wall structures.In this study,four new pinless tools with different groove distributions were designed and manufactured in order to enrich technological storage of PFSW and obtain sound joint with high quality of alclad 2A12-T4 alloy.The results show that the small-obliquity tool is detrimental to the transfer of plasticized materials,resulting in the formation of kissing bond defect.For the through-groove tool or the large-curvature tool,bigger flashes form on the joint surface and alclad layer is observed in the nugget zone(NZ),deteriorating mechanical properties.Compared with the above-mentioned three tools,using the six-groove tool with rational curvature and obliquity can not only yield sound joint with small flashes and thickness reduction,but also prevent alclad from flowing into NZ,which has potential to weld thin alclad aluminum alloys.Meanwhile,the tensile strength and elongation of joint using the six-groove tool reach the maximum values of 362 MPa and 8.3%,up to 85.1% and 64% of BM. 展开更多
关键词 Pinless friction stir welding Groove distribution 2A12-T4 aluminum alloy Macrostructures Mechanical property
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