期刊文献+
共找到2,155篇文章
< 1 2 108 >
每页显示 20 50 100
Can environmental sustainability be decoupled from economic growth? Empirical evidence from Eastern Europe using the common correlated effect mean group test 被引量:1
1
作者 Kwaku ADDAI Berna SERENER Dervis KIRIKKALELI 《Regional Sustainability》 2023年第1期68-80,共13页
The European Union(EU) and Organisation for Economic Co-operation and Development(OECD) aim to develop long-term policies for their respective member countries. Having observed increasing dangers to the environment po... The European Union(EU) and Organisation for Economic Co-operation and Development(OECD) aim to develop long-term policies for their respective member countries. Having observed increasing dangers to the environment posed by rising economic growth, they are seeking pathways to enable policy action on economic growth and environmental sustainability. Given the facts in theoretical and empirical studies, this study assessed the validity of the decoupling hypothesis by investigating asymmetricity in the relationship between environmental sustainability and economic growth in nine Eastern European countries from 1998 to 2017 using the cross-section augmented Dickey-Fuller(CADF) unit root, panel corrected standard error(PCSE), common correlated effect mean group(CCEMG), and Dumitrescu Hurlin causality approaches. Both population growth and drinking water are used as controlled variables. The outcomes establish strong cointegration among all the variables of interest. According to the results of CCEMG test, economic growth exerts short-term environmental degradation but has long-term environmental benefits in Eastern Europe;and population growth and drinking water exert a positive effect on environmental sustainability in both the short-and long-run. The results of Dumitrescu Hurlin causality test indicate that environmental sustainability is unidirectionally affected by economic growth. Based on these outcomes, we suggest the following policies:(1) the EU and OECD should implement member-targeted policies on economic growth and fossil-fuel use towards regulating industrial pollution, water use, and population control;and(2) the EU and OECD member countries should invest in environmental technologies through green research and development(R&D) to transform their dirty industrial processes and ensure productive energy use. 展开更多
关键词 Economic growth Environment sustainability Decoupling Carbon emissions Eastern Europe Common correlated effect mean group(CCEMG)test Econometrics Population growth
下载PDF
Effects of the Reynolds number on a scale-similarity model of Lagrangian velocity correlations in isotropic turbulent flows 被引量:1
2
作者 Zhaoyu SHI Jincai CHEN Guodong JIN 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第11期1605-1616,共12页
A scale-similarity model of a two-point two-time Lagrangian velocity correlation(LVC) was originally developed for the relative dispersion of tracer particles in isotropic turbulent flows(HE, G. W., JIN, G. D., and ZH... A scale-similarity model of a two-point two-time Lagrangian velocity correlation(LVC) was originally developed for the relative dispersion of tracer particles in isotropic turbulent flows(HE, G. W., JIN, G. D., and ZHAO, X. Scale-similarity model for Lagrangian velocity correlations in isotropic and stationary turbulence. Physical Review E, 80, 066313(2009)). The model can be expressed as a two-point Eulerian space correlation and the dispersion velocity V. The dispersion velocity denotes the rate at which one moving particle departs from another fixed particle. This paper numerically validates the robustness of the scale-similarity model at high Taylor micro-scale Reynolds numbers up to 373, which are much higher than the original values(R_λ = 66, 102). The effect of the Reynolds number on the dispersion velocity in the scale-similarity model is carefully investigated. The results show that the scale-similarity model is more accurate at higher Reynolds numbers because the two-point Lagrangian velocity correlations with different initial spatial separations collapse into a universal form compared with a combination of the initial separation and the temporal separation via the dispersion velocity.Moreover, the dispersion velocity V normalized by the Kolmogorov velocity V_η ≡ η/τ_η in which η and τ_η are the Kolmogorov space and time scales, respectively, scales with the Reynolds number R_λ as V/V_η ∝ R_λ^(1.39) obtained from the numerical data. 展开更多
关键词 turbulent mixing relative dispersion Lagrangian velocity correlation scalesimilarity model dispersion velocity Reynolds number effect
下载PDF
Inversion of time-domain airborne EM data with IP effect based on Pearson correlation constraints 被引量:1
3
作者 Man Kai-Feng Yin Chang-Chun +4 位作者 Liu Yun-He Ren Xiu-Yan Sun Si-Yuan Miao Jia-Jia Xiong Bin 《Applied Geophysics》 SCIE CSCD 2020年第4期589-600,共12页
Due to the induced polarization(IP)eff ect,the sign reversal often occurs in timedomain airborne electromagnetic(AEM)data.The inversions that do not consider IP eff ect cannot recover the true umderground electrical s... Due to the induced polarization(IP)eff ect,the sign reversal often occurs in timedomain airborne electromagnetic(AEM)data.The inversions that do not consider IP eff ect cannot recover the true umderground electrical structures.In view of the fact that there are many parameters of airborne induced polarization data in time domain,and the sensitivity diff erence between parameters is large,which brings challenges to the stability and accuracy of the inversion.In this paper,we propose an inversion mehtod for time-domain AEM data with IP effect based on the Pearson correlation constraints.This method uses the Pearson correlation coeffi cient in statistics to characterize the correlation between the resistivity and the chargeability and constructs the Pearson correlation constraints for inverting the objective function to reduce the non uniqueness of inversion.To verify the eff ectiveness of this method,we perform both Occam’s inversion and Pearson correlation constrained inversion on the synthetic data.The experiments show that the Pearson correlation constrained inverison is more accurate and stable than the Occam’s inversion.Finally,we carried out the inversion to a survey dataset with and without IP eff ect.The results show that the data misfit and the continuity of the inverted section are greatly improved when the IP eff ect is considered. 展开更多
关键词 Time-domain AEM induced polarization effect forward modeling INVERSION Pearson correlation constraints
下载PDF
Spin Supercurrent in Phenomena of Quantum Non-Locality (Quantum Correlations, Magnetic Vector Potential) and in Near-Field Antenna Effect 被引量:1
4
作者 Liudmila B. Boldyreva 《Journal of Modern Physics》 2019年第2期128-144,共17页
It is shown that such phenomena as quantum correlations (interaction of space-separated quantum entities), the action of magnetic vector potential on quantum entities in the absence of magnetic field, and near-field a... It is shown that such phenomena as quantum correlations (interaction of space-separated quantum entities), the action of magnetic vector potential on quantum entities in the absence of magnetic field, and near-field antenna effect (the existence of superluminally propagating electromagnetic fields) may be explained by action of spin supercurrents. In case of quantum correlations between quantum entities, spin supercurrent emerges between virtual particles pairs (virtual photons) created by those quantum entities. The explanation of magnetic vector potential and near-field antenna effect is based on contemporary principle of quantum mechanics: the physical vacuum is not an empty space but the ground state of the field consisting of quantum harmonic oscillators (QHOs) characterized by zero-point energy. Using the properties of the oscillators and spin supercurrent, it is proved that magnetic vector potential is proportional to the moment causing the orientation of spin of QHO along the direction of magnetic field. The near-field antenna effect is supposed to take place as a result of action of spin supercurrent causing secondary electromagnetic oscillations. In this way, the electromagnetic field may spread at the speed of spin supercurrent. As spin supercurrent is an inertia free process, its speed may be greater than that of light, which does not contradict postulates of special relativity that sets limits to the speed of inertial systems only. 展开更多
关键词 SPIN SUPERCURRENT QUANTUM correlations Magnetic Vector Potential NEAR-FIELD Antenna effect Zero-Point Energy QUANTUM Harmonic Oscillator VIRTUAL Particles Pair VIRTUAL Photon
下载PDF
Correlation effects on the fine-structure splitting within the 3d9 ground configuration in highly-charged Co-like ions
5
作者 郭学玲 黄敏 +4 位作者 颜君 李双 王凯 司然 陈重阳 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第1期535-542,共8页
A comprehensive theoretical study of correlation effects on the fine-structure splitting within the ground configuration 3d9 of the Co-like HI45+, Ta46+, W47+, and Au52+ ions is performed by employing the multi-co... A comprehensive theoretical study of correlation effects on the fine-structure splitting within the ground configuration 3d9 of the Co-like HI45+, Ta46+, W47+, and Au52+ ions is performed by employing the multi-configuration Dirac-Hartree- Fock method in the active space approximation. It shows that the core-valence correlation with the inner-core 2p electron is more significant than with the outer 3p and 3s electrons, and the correlation with the 2s electron is also noticeable. The core-core correlation seems to be small and can be ignored. The calculated 2D3/2,5/2 splitting energies agree with the recent electron-beam ion-trap measurements [Phys. Rev. A 83 032517 (2011), Eur. Phys. J. D 66 286 (2012)] to within the experimental uncertainties. 展开更多
关键词 correlation effects multi-configuration Dirac-Hartree-Fock method high-Z Co-like ions fine- structure splitting
下载PDF
Adaptive Random Effects/Coefficients Modeling
6
作者 George J. Knafl 《Open Journal of Statistics》 2024年第2期179-206,共28页
Adaptive fractional polynomial modeling of general correlated outcomes is formulated to address nonlinearity in means, variances/dispersions, and correlations. Means and variances/dispersions are modeled using general... Adaptive fractional polynomial modeling of general correlated outcomes is formulated to address nonlinearity in means, variances/dispersions, and correlations. Means and variances/dispersions are modeled using generalized linear models in fixed effects/coefficients. Correlations are modeled using random effects/coefficients. Nonlinearity is addressed using power transforms of primary (untransformed) predictors. Parameter estimation is based on extended linear mixed modeling generalizing both generalized estimating equations and linear mixed modeling. Models are evaluated using likelihood cross-validation (LCV) scores and are generated adaptively using a heuristic search controlled by LCV scores. Cases covered include linear, Poisson, logistic, exponential, and discrete regression of correlated continuous, count/rate, dichotomous, positive continuous, and discrete numeric outcomes treated as normally, Poisson, Bernoulli, exponentially, and discrete numerically distributed, respectively. Example analyses are also generated for these five cases to compare adaptive random effects/coefficients modeling of correlated outcomes to previously developed adaptive modeling based on directly specified covariance structures. Adaptive random effects/coefficients modeling substantially outperforms direct covariance modeling in the linear, exponential, and discrete regression example analyses. It generates equivalent results in the logistic regression example analyses and it is substantially outperformed in the Poisson regression case. Random effects/coefficients modeling of correlated outcomes can provide substantial improvements in model selection compared to directly specified covariance modeling. However, directly specified covariance modeling can generate competitive or substantially better results in some cases while usually requiring less computation time. 展开更多
关键词 Adaptive Regression correlated Outcomes Extended Linear Mixed Modeling Fractional Polynomials Likelihood Cross-Validation Random effects/Coefficients
下载PDF
Analysis of genetic effects and correlations for nutrient quality traits of indica rice in different environments 被引量:9
7
作者 SHI Chunhai and ZHU Jun , Agronomy Dept YANG Xiaoe, XUE Jianming , and YU Yonggui, Dept of Soil Sci and Agri Chem, Zhejiang Agri Univ, Hangzhou 310029, China 《Chinese Rice Research Newsletter》 1997年第1期2-4,共3页
Understanding the variation for the expressionof genes in different environments is one of themajor goals in qualitative genetics. In this pa-per, the genetic models for quantitative traitsof endosperm in cereal crops... Understanding the variation for the expressionof genes in different environments is one of themajor goals in qualitative genetics. In this pa-per, the genetic models for quantitative traitsof endosperm in cereal crops were used to eval-uate the seed, cytoplasm and maternal geneticeffects as well as the genotype × environment(GE) interaction effects, and to predict thebreeding value of parents and genotypic corre-lation for nutrient quality traits of indica rice (Oryza sativa L.). 展开更多
关键词 Analysis of genetic effects and correlations for nutrient quality traits of indica rice in different environments
下载PDF
Spin-Polarized Transport Through a Quantum Dot Coupled to Ferromagnetic Leads: Kondo Correlation Effect
8
作者 MAJing DONGBing LEIXiao-Lin 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第2期341-348,共8页
We investigate the linear and nonlinear transport through a single level quantum dot connected to two ferromagnetic leads in Kondo regime, using the slave-boson mean-field approach for finite on-site Coulomb repulsion... We investigate the linear and nonlinear transport through a single level quantum dot connected to two ferromagnetic leads in Kondo regime, using the slave-boson mean-field approach for finite on-site Coulomb repulsion. We find that for antiparallel alignment of the spin orientations in the leads, a single zero-bias Kondo peak always appears in the voltage-dependent differential conductance with peak height going down to zero as the polarization grows to P = 1.For parallel configuration, with increasing polarization from zero, the Kondo peak descends and greatly widens with the appearance of shoulders, and finally splits into two peaks on both sides of the bias voltage around P ~ 0.7 until disappearing at even larger polarization strength. At any spin orientation angle θ, the linear conductance generally drops with growing polarization strength. For a given finite polarization, the minimum linear conductance always appears at θ = π. 展开更多
关键词 quantum dot kondo correlation effect TRANSPORT
下载PDF
Diagrammatic Iteration Approach to Electron Correlation Effects
9
作者 J. D. Fan Y. M. Malozovsky 《Journal of Modern Physics》 2014年第7期549-561,共13页
Electron correlation is a measure of the errors that are inherent in the Hartree-Fock theory or orbital models. When the electron density is high, correlation is weak and the traditional electronic theory works well. ... Electron correlation is a measure of the errors that are inherent in the Hartree-Fock theory or orbital models. When the electron density is high, correlation is weak and the traditional electronic theory works well. However, at a low density of electrons correlation effects become strong and the traditional theory fails to describe the electron system correctly. Therefore, the electron correlation plays a radical role in such materials as high-temperature superconductors and heavy fermions, etc. To date, there is no agreement on how to deal with higher-order terms (correlation energy) in the series of electron’s ground state energy although a method that is termed diagrammatic iteration approach (DIA) was developed more than one decade ago by the authors of this article. That is why no consensus on the origin and mechanism of superconductivity has been engaged in superconductivity community. From the viewpoint of methodology, the DIA is indeed an approach to higher-order terms from the lower-order ones, i.e. it is a new method to show how to go beyond the random phase approximation (RPA) step by step by iteration. Here, we are logically presenting it to the community of modern physics with more analyses and hope to attract more attention to it and promote its applications. 展开更多
关键词 ELECTRON correlation effect Diagrammatic ITERATION APPROACH SUPERCONDUCTIVITY Condensed MATTER PHYSICS
下载PDF
Dose-effect correlation of chloride de-icing salt on Euonymus japonicus 被引量:1
10
作者 Zhou-Yuan LI Jun-Hui ZHOU Ying-Mei LIANG 《Forestry Studies in China》 CAS 2013年第3期238-245,共8页
In order to prevent severe pollution by de-icing salt on greenery along urban roads, a half lethal dose (LD_50)for a plant population was confirmed through stress simulation of chloride de-icing salt on Euonymus jap... In order to prevent severe pollution by de-icing salt on greenery along urban roads, a half lethal dose (LD_50)for a plant population was confirmed through stress simulation of chloride de-icing salt on Euonymus japonicus, with an ianalysis of physiological changes, statistics on mortality rate on plant populations and mathematic modeling during a 30- day subacute toxicity test. The results indicate that a significant positive correlation in the early stages and a significant negative correlation in the later stages were observed between the amount of chlorophyll a and b in plants and a cumulative dose of de-icing salt. The amounts of free proline in plants and the dose of de-icing salt were positively correlated Over the entire period. No significant correlation in the initial stage, but a significant negative correlation in later stages was observed between the soluble protein and the dose of de-icing salt. LDs0 of this chloride agent on E. japonicus is 5 kg.(L·m2)-1 over 30 days. 展开更多
关键词 de-icing salt Euonymus japonicus dose-effect correlation half lethal dose
下载PDF
Effect of Electron Correlation and Breit Interaction on Energies, Oscillator Strengths, and Transition Rates for Low-Lying States of Helium
11
作者 Qing Liu Jiguang Li +1 位作者 Jianguo Wang Yizhi Qu 《Chinese Physics Letters》 SCIE CAS CSCD 2021年第11期23-29,共7页
The transition energies, E1 transitional oscillator strengths of the spin-allowed as well as the spin-forbidden and the corresponding transition rates, and complete M1, E2, M2 forbidden transition rates for 1s^(2), 1s... The transition energies, E1 transitional oscillator strengths of the spin-allowed as well as the spin-forbidden and the corresponding transition rates, and complete M1, E2, M2 forbidden transition rates for 1s^(2), 1s2s, and 1s2p states of He I, are investigated using the multi-configuration Dirac–Hartree–Fock method. In the subsequent relativistic configuration interaction computations, the Breit interaction and the QED effect are considered as perturbation, separately. Our transition energies, oscillator strengths, and transition rates are in good agreement with the experimental and other theoretical results. As a result, the QED effect is not important for helium atoms, however, the effect of the Breit interaction plays a significant role in the transition energies, the oscillator strengths and transition rates. 展开更多
关键词 QED DIRAC Oscillator Strengths and Transition Rates for Low-Lying States of Helium effect of Electron correlation and Breit Interaction on Energies
下载PDF
Electron Correlation Effects in Polaron-Pair Recombination in Conjugated Polymers
12
作者 赵红霞 赵晖 +1 位作者 陈宇光 鄢永红 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第4期85-89,共5页
Within a Su-Schriffer-Heeger model modified to include electron-electron interaction and an external electric field, we investigate the dynamics of oppositely charged polarons in a polymer chain in the presence of bot... Within a Su-Schriffer-Heeger model modified to include electron-electron interaction and an external electric field, we investigate the dynamics of oppositely charged polarons in a polymer chain in the presence of both electron-phonon and electron-electron interactions under the influence of an external electric field. We adopt a multi-configurational time-dependent Hartree-Fock method for the time-dependent Schrodinger equation and the Newtonian equation of motion for a lattice. Our results show that the on-site Coulomb interaction is of fundamental importance and favors the recombination between the pairs of polarons, and the yield of excitons depends crucially on the strength of the on-site Coulomb interaction U. Furthermore, the influence of the nearest neighbor interaction V is also discussed. 展开更多
关键词 Electron correlation effects in Polaron-Pair Recombination in Conjugated Polymers
下载PDF
Correlation between current intensity and effective duration in the treatment of botulinus toxin for cerebral palsy by myoelectricity locating
13
作者 Jianjun Liu Shurong Ji Yingyuan Hu Yanchun Li Weihong Wu Huabao Lu Yan Zhang 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第4期361-363,共3页
BACKGROUND: Researches prove that the treatment of cerebral palsy by botulinus toxin (BTX-A) can improve effect and prolong effective duration. Current intensity is the important factor during injection. OBJECTIVE... BACKGROUND: Researches prove that the treatment of cerebral palsy by botulinus toxin (BTX-A) can improve effect and prolong effective duration. Current intensity is the important factor during injection. OBJECTIVE: To observe the changes of motor function and muscular intensity of children with spastic cerebral palsy after injecting BTX-A and analyze correlation between current intensity and effective duration. DESIGN: Cases control trial before and after nerves block SETTING: Capital University of Medical Sciences, China Rehabilitation Research Center PARTICIPANTS: From June 2002 to November 2004, 14 children with spastic cerebral palsy were treated by BTX-A block. All children were hospitalized in the Children Rehabilitation Department of China Rehabilitation Research Center. The children included 9 male and 5 female, and ranged from 4 to 13 years old, and average age was (6±2) years. Muscular tension ranged from grade 1 to grade 3. The diagnosis and the tape of cerebral palsy based on standard of the Fist Nationwide Cerebral Palsy Symposium, and all children were diagnosed with electroencephalogram (EEG), CT and MRI, and permitted by their guardians. METHODS: (1) Locating and calculation: To locate block points by G6805-2A electro-therapeutic apparatus (Shanghai Huayi Electronic Instrument Plant) at the least stimulating current (continuous wave; impulse frequency; 2.667-83.333 Hz; current intensity: 0-6 mA; voltage: 6 V) to touch off muscles contraction. The current intensity of each point was recorded, and the average current intensity of each patient was calculated at the same time. (2) Dose of BTX-A: Basing upon the spastic degree and weight of patients, the dose was made certain: dose (IU)=(scores of Modified Ashworth Scale +2.5) xweight (kg). The number of the block points was in all 4. The dose of injection ranged from 50 IU to 160 IU with the average of (73.6+25.8) IU. The BTX-A was made by Lanzhou Institute of Biological Products, and each bottle contains 100 IU BTX-A. Muscular tension was evaluated by Modified Ashworth Scale. The scale ranged from grade 0 to grade 4, and the scores were from 0 to 4. The higher the scores were, the higher the muscular tension was. (3) Effect: Changes of muscular tension were evaluated by modified Ashworth Scale before and after block. Motor function was evaluated by Physician Rating Scale (PRS) before and after treatment. It contained Gait pattern, Hindfoot (ankle) position (stance-floor contact), Hindfoot position (foot strike), Knee position (degree of recurvation), Crouch and Speed of gait. The scores ranged from 0 to 14. The higher the points were, the better the motor function was. (4) Effective duration: The duration was definited by the recovering of the Modified Ashworth Scale. (5) Statistic analysis: Firstly, the current intensity and the effect duration were analyzed by One-Sample Kolmogorov-Smirnov Test, the current intensity: Z= 0.456, P= 0.985, the effective duration: Z= 0.557, P= 0.915. Both data were normal distribution. Secondly, both data were analyzed by Linear Regression. The efficiency of the BTX-A block was analyzed by paired-samples t test. MAIN OUTCOME MEASURES: (1) Changes of motor function of muscular tension; (2) correlation between current intensity and effective duration. RESULTS: Fourteen children with spastic cerebral palsy were all involved in the final analysis. (1) Therapeutic effect: The average score of Ashworth scale after block was lower than that before block [(1.02±0.34) points vs. (2.12±0.48) points, t= 3.644, P〈 0.01]. The average score of RPS after block was higherthan that before block [(9.75±2.78) points vs. (6.16±0.58) points, t =13.222, P〈 0.01]. (2) Relation between the current intensity and the effective duration: The current intensity was (0.1857±0.0506) mA, and the effective duration was (26.36±4.48) weeks. The current intensity was negative correlation with effective duration (r = -0.775, P = 0.01 ). CONCLUSION: (1) BTX-A occlusion can decrease muscular tension and improve motor function of lower limbs of children with spastic cerebral palsy. (2) The lower the current intensity is, the longer the effective duration is. 展开更多
关键词 correlation between current intensity and effective duration in the treatment of botulinus toxin for cerebral palsy by myoelectricity locating BTX
下载PDF
Correlation between Electrical Conductivity and Microwave Shielding Effectiveness of Natural Rubber Based Composites, Containing Different Hybrid Fillers Obtained by Impregnation Technology
14
作者 Ahmed A. Al-Ghamdi Omar A. Al-Hartomy +4 位作者 Falleh R. Al-Solamy Nikolay T. Dishovsky Petrunka Malinova Nikolay T. Atanasov Gabriela L. Atanasova 《Materials Sciences and Applications》 2016年第9期496-509,共14页
The paper presents the synthesis and characterization of carbon black/silicone dioxide hybrid fillers obtained by an impregnation technology. The electromagnetic interference shielding effectiveness of the composites ... The paper presents the synthesis and characterization of carbon black/silicone dioxide hybrid fillers obtained by an impregnation technology. The electromagnetic interference shielding effectiveness of the composites filled with carbon black/silicone dioxide hybrid fillers was measured in wide frequency range of 1 - 12 GHz. The dc and ac electrical conductivity of composites also have been investigated. The relationship between electrical (dc and ac) conductivity and shielding effectiveness was analyzed. A positive correlation was found between the absorptive shielding effectiveness and ac conductivity for composites comprising conductive carbon black/silica filler, when the filler loading is above the percolation threshold. 展开更多
关键词 Composite Materials correlation Electrical Conductivity Shielding effectiveness
下载PDF
Correlation Method of Average Plasma Velocity Measurement in Hall-Effect Thrusters
15
作者 宁中喜 李鸿 于达仁 《Plasma Science and Technology》 SCIE EI CAS CSCD 2009年第6期709-713,共5页
A new method to measure the average plasma velocity in a Hall-effect thruster is presented. The method is brought forward in virtue of the characteristics of low frequency oscillation induced by the propellant ionizat... A new method to measure the average plasma velocity in a Hall-effect thruster is presented. The method is brought forward in virtue of the characteristics of low frequency oscillation induced by the propellant ionization in the channel and the oriented movement feature of the plasma density out of the channel. The method, equivalent to the correlation method generally used in the signal processing field, provides a solution to the problem of specific impulse measurement on a timescale of hundreds of microseconds and makes the time evolution of average plasma velocity clear. The comparison between the measured value and the calibrated value shows that the relative error is about 3%. 展开更多
关键词 Hall-effect thruster average plasma velocity correlation method
下载PDF
RS-based Analysis of the Correlation between Brightness Temperature and Vegetation Cover—A Case Study of Neijiang City,Sichuan Province of China
16
作者 薛万蓉 许辉熙 +2 位作者 但尚铭 何政伟 仇文侠 《Journal of Landscape Research》 2012年第2期35-37,共3页
Landsat TM data(June 23,1988,May 6,2007) and Landsat ETM+data(May 10,2000) of Neijiang City,Sichuan Province was taken as the data source,brightness temperature of the study area was obtained by using TM/ETM+thermal i... Landsat TM data(June 23,1988,May 6,2007) and Landsat ETM+data(May 10,2000) of Neijiang City,Sichuan Province was taken as the data source,brightness temperature of the study area was obtained by using TM/ETM+thermal infrared wave,and also normalized difference vegetation index(NDVI) was calculated.NDVI of the study area on June 23,1988,May 6,2007,and May 10,2000 was respectively obtained by using Band Math,the least square fitting was adopted to simulate the correlation between surface temperature and vegetation cover.Moreover,linear regression analysis of the correlation between vegetation cover and NDVI was carried out in Excel.The results showed that(a) most of the constructed area has a low NDVI value because there are large areas of hard surface such as buildings and roads,but less vegetation cover;(b) the quarters with better vegetation cover have higher NDVI values;the Tuojiang River has a negative NDVI value;rural areas have better vegetation cover and higher NDVI values.Brightness temperature and vegetation cover has distinct negative correlation,specifically,the higher the vegetation cover is,the lower the surface temperature is,and vice versa. 展开更多
关键词 Urban heat ISLAND effects Remote sensing(RS) BRIGHTNESS temperature Normalized difference VEGETATION index(NDVI) correlation ANALYSIS
全文增补中
Preliminary research on the relationship between long-range correlations and predictability 被引量:1
17
作者 张志森 龚志强 +2 位作者 支蓉 封国林 胡经国 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第1期23-32,共10页
By establishing the Markov model for a long-range correlated time series (LRCS) and analysing its evolutionary characteristics, this paper defines a physical effective correlation length (ECL) T, which reflects th... By establishing the Markov model for a long-range correlated time series (LRCS) and analysing its evolutionary characteristics, this paper defines a physical effective correlation length (ECL) T, which reflects the predictability of the LRCS. It also finds that the ECL has a better power law relation with the long-range correlated exponent γ of the LRCS: T = Kexp(-γ/0.3) + Y, (0 〈 γ〈 1) the predictability of the LRCS decays exponentially with the increase of γ It is then applied to a daily maximum temperature series (DMTS) recorded at 740 stations in China between the years 1960-2005 and calculates the ECL of the DMTS. The results show the remarkable regional distributive feature that the ECL is about 10-14 days in west, northwest and northern China, and about 5-10 days in east, southeast and southern China. Namely, the predictability of the DMTS is higher in central-west China than in east and southeast China. In addition, the ECL is reduced by 1-8 days in most areas of China after subtracting the seasonal oscillation signal of the DMTS from its original DMTS; however, it is only slightly altered when the decadal linear trend is removed from the original DMTS. Therefore, it is shown that seasonal oscillation is a significant component of daily maximum temperature evolution and may provide a basis for predicting daily maximum temperatures. Seasonal oscillation is also significant for guiding general weather predictions, as well as seasonal weather predictions. 展开更多
关键词 long-range correlation information entropy effective correlation length PREDICTABILITY
下载PDF
Correlation between catalytic activity of supported gold catalysts for carbon monoxide oxidation and metal–oxygen binding energy of the support metal oxides 被引量:3
18
作者 Takashi Fujita Masanori Horikawa +2 位作者 Takashi Takei Tom Murayama Masatake Haruta 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第10期1651-1655,共5页
The effect of a wide variety of metal oxide (MOx) supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under id... The effect of a wide variety of metal oxide (MOx) supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50%conversion was measured to qualita‐tively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano‐like correla‐tion between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies (300–500 kJ/atom O) greatly improves the catalytic activity of MOx by the deposition of Au NPs. 展开更多
关键词 Metal oxide-supported gold nanoparticle catalyst Support effects Carbon monoxide oxidation Volcano-like correlation Metal-oxygen binding energy
下载PDF
Uncertainty evaluation and correlation analysis of single-particle energies in phenomenological nuclear mean field:an investigation into propagating uncertainties for independent model parameters 被引量:1
19
作者 Zhen-Zhen Zhang Hua-Lei Wang +1 位作者 Hai-Yan Meng Min-Liang Liu 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2021年第2期45-57,共13页
Based on the Monte Carlo approach and conventional error analysis theory,taking the heaviest doubly magic nucleus 208Pb as an example,we first evaluate the propagated uncertainties of universal potential parameters fo... Based on the Monte Carlo approach and conventional error analysis theory,taking the heaviest doubly magic nucleus 208Pb as an example,we first evaluate the propagated uncertainties of universal potential parameters for three typical types of single-particle energy in the phenomenological Woods–Saxon mean field.Accepting the Woods–Saxon modeling with uncorrelated model parameters,we found that the standard deviations of singleparticle energy obtained through the Monte Carlo simulation and the error propagation rules are in good agreement.It seems that the energy uncertainty of the single-particle levels regularly evoluate with certain quantum numbers to a large extent for the given parameter uncertainties.Further,the correlation properties of the single-particle levels within the domain of input parameter uncertainties are statistically analyzed,for example,with the aid of Pearson’s correlation coefficients.It was found that a positive,negative,or unrelated relationship may appear between two selected single-particle levels,which will be extremely helpful for evaluating the theoretical uncertainty related to the single-particle levels(e.g.,K isomer)in nuclear structural calculations. 展开更多
关键词 Uncertainty propagation correlation effect Woods-Saxon potential
下载PDF
Determination of Causal Effect in Observational Studies: Analysis of Correlated Data with Binary End-Points 被引量:1
20
作者 Maupi Eric Letsoalo Maseka Lesaoana 《Journal of Mathematics and System Science》 2012年第2期119-125,共7页
Identifying the causal impact of' some intervention challenging when one is faced with correlated binary end-points in observational studies is a challenging task, and it is even more The statistical literature on an... Identifying the causal impact of' some intervention challenging when one is faced with correlated binary end-points in observational studies is a challenging task, and it is even more The statistical literature on analyzing such data is well documented. Dependence between observations from the same study subject in correlated data renders invalid the usual chi-square tests of independence and inflates the variance ofparameter estimates. Disaggregated approaches such as hierarchical linear models which are able to adjust for individual level covariate:s are favoured in the analysis of such data, thereby gaining power over aggregated and individual-level analyses. In this article the authors, therefore, address the issue of analyzing correlated data with dichotomous end-points by using hierarchical logistic regression, a generalization of the standard logistic regression model for independent outcomes. 展开更多
关键词 correlated data observational studies counterfactual problem hierarchical models group randomization treatment effect.
下载PDF
上一页 1 2 108 下一页 到第
使用帮助 返回顶部