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Empirical likelihood for spatial cross-sectional data models with matrix exponential spatial specification
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作者 LIU Yan RONG Jian-rong QIN Yong-song 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2024年第1期125-139,共15页
In this paper,we study spatial cross-sectional data models in the form of matrix exponential spatial specification(MESS),where MESS appears in both dependent and error terms.The empirical likelihood(EL)ratio statistic... In this paper,we study spatial cross-sectional data models in the form of matrix exponential spatial specification(MESS),where MESS appears in both dependent and error terms.The empirical likelihood(EL)ratio statistics are established for the parameters of the MESS model.It is shown that the limiting distributions of EL ratio statistics follow chi-square distributions,which are used to construct the confidence regions of model parameters.Simulation experiments are conducted to compare the performances of confidence regions based on EL method and normal approximation method. 展开更多
关键词 MESS empirical likelihood con dence region
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Anisotropic time-dependent behaviors of shale under direct shearing and associated empirical creep models
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作者 Yachen Xie Michael Z.Hou +1 位作者 Hejuan Liu Cunbao Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1262-1279,共18页
Understanding the anisotropic creep behaviors of shale under direct shearing is a challenging issue.In this context,we conducted shear-creep and steady-creep tests on shale with five bedding orientations (i.e.0°,... Understanding the anisotropic creep behaviors of shale under direct shearing is a challenging issue.In this context,we conducted shear-creep and steady-creep tests on shale with five bedding orientations (i.e.0°,30°,45°,60°,and 90°),under multiple levels of direct shearing for the first time.The results show that the anisotropic creep of shale exhibits a significant stress-dependent behavior.Under a low shear stress,the creep compliance of shale increases linearly with the logarithm of time at all bedding orientations,and the increase depends on the bedding orientation and creep time.Under high shear stress conditions,the creep compliance of shale is minimal when the bedding orientation is 0°,and the steady-creep rate of shale increases significantly with increasing bedding orientations of 30°,45°,60°,and 90°.The stress-strain values corresponding to the inception of the accelerated creep stage show an increasing and then decreasing trend with the bedding orientation.A semilogarithmic model that could reflect the stress dependence of the steady-creep rate while considering the hardening and damage process is proposed.The model minimizes the deviation of the calculated steady-state creep rate from the observed value and reveals the behavior of the bedding orientation's influence on the steady-creep rate.The applicability of the five classical empirical creep models is quantitatively evaluated.It shows that the logarithmic model can well explain the experimental creep strain and creep rate,and it can accurately predict long-term shear creep deformation.Based on an improved logarithmic model,the variations in creep parameters with shear stress and bedding orientations are discussed.With abovementioned findings,a mathematical method for constructing an anisotropic shear creep model of shale is proposed,which can characterize the nonlinear dependence of the anisotropic shear creep behavior of shale on the bedding orientation. 展开更多
关键词 Rock anisotropy Direct shear creep Creep compliance Steady-creep rate empirical model Creep constitutive model
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Research on the longitudinal protection of a through-type cophase traction direct power supply system based on the empirical wavelet transform
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作者 Lu Li Zeduan Zhang +5 位作者 Wang Cai Qikang Zhuang Guihong Bi Jian Deng Shilong Chen Xiaorui Kan 《Global Energy Interconnection》 EI CSCD 2024年第2期206-216,共11页
This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a disti... This paper proposes a longitudinal protection scheme utilizing empirical wavelet transform(EWT)for a through-type cophase traction direct power supply system,where both sides of a traction network line exhibit a distinctive boundary structure.This approach capitalizes on the boundary’s capacity to attenuate the high-frequency component of fault signals,resulting in a variation in the high-frequency transient energy ratio when faults occur inside or outside the line.During internal line faults,the high-frequency transient energy at the checkpoints located at both ends surpasses that of its neighboring lines.Conversely,for faults external to the line,the energy is lower compared to adjacent lines.EWT is employed to decompose the collected fault current signals,allowing access to the high-frequency transient energy.The longitudinal protection for the traction network line is established based on disparities between both ends of the traction network line and the high-frequency transient energy on either side of the boundary.Moreover,simulation verification through experimental results demonstrates the effectiveness of the proposed protection scheme across various initial fault angles,distances to faults,and fault transition resistances. 展开更多
关键词 Through-type Cophase traction direct power supply system Traction network empirical wavelet transform(EWT) Longitudinal protection
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Evaluation and Empirical Research on Teachers’ Information Literacy in the Context of Smart Education
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作者 Chenyue Hu 《Journal of Contemporary Educational Research》 2024年第3期211-220,共10页
The development of smart education has led to the integration of emerging technologies such as artificial intelligence with education.It is a prerequisite for teachers to have high information literacy for conducting ... The development of smart education has led to the integration of emerging technologies such as artificial intelligence with education.It is a prerequisite for teachers to have high information literacy for conducting education and teaching work.This study conducted a questionnaire survey on 412 teachers in a certain area.The results showed that teachers’information literacy is above the middle level,and there are significant differences in information literacy between teaching experience and educational background.The evaluation showed that information ethics,information awareness,and information application have a significant positive impact on professional development,and information knowledge and information awareness have a positive predictive effect on information ethics. 展开更多
关键词 Teachers’information literacy Smart education empirical research
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Empirical Investigation of Treatment of Sour Gas by Novel Technology: Energy Optimization
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作者 Ehsan Monfared Farshad Farahbod 《American Journal of Analytical Chemistry》 CAS 2023年第4期175-183,共9页
The sour gas sweetening is one of the main processes in gas industries. Gas sweetening is done through chemical processes. Therefore, it requires high cost and energy. The results show that increasing the operating te... The sour gas sweetening is one of the main processes in gas industries. Gas sweetening is done through chemical processes. Therefore, it requires high cost and energy. The results show that increasing the operating temperature increases the mass transfer coefficient and increases the mass transfer rate. Theoretical and experimental data show that sulfur removal in 4.5 W magnetic field is desirable. The increase in sulfur removal percentage in the magnetic field of 4.5 W and 6.75 W is about 16.4% and 15.2%, respectively. According to the obtained results, the effect of temperature increase from 18.8°C to 23.4°C is more evident than the effect of temperature change from 23.4°C to 32.2°C. Because more thermal energy is needed to provide higher temperatures. Therefore, the temperature of 23.4°C is reported as the optimal temperature. The results of this research show that the percentage of sulfur removal is also high at this temperature. 展开更多
关键词 Oil and Gas Industries Optimized Energy Treatment Process empirical Investigation
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SPAGINS:semiempirical parameterization for fragments in gamma-induced nuclear spallation
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作者 Hui‑Ling Wei Meng‑Die Zhou +8 位作者 Pu Jiao Yu‑Ting Wang Jie Pu Kai‑Xuan Cheng Ya‑Fei Guo Chun‑Yuan Qiao Gong‑Tao Fan Hong‑Wei Wang Chun‑Wang Ma 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第12期112-122,共11页
From the empirical phenomena of fragment distributions in nuclear spallation reactions,semiempirical formulas named SPAGINS were constructed to predict fragment cross-sections in high-energyγ-induced nuclear spallati... From the empirical phenomena of fragment distributions in nuclear spallation reactions,semiempirical formulas named SPAGINS were constructed to predict fragment cross-sections in high-energyγ-induced nuclear spallation reactions(PNSR).In constructing the SPAGINS formulas,theoretical models,including the TALYS toolkit,SPACS,and Rudstam formulas,were employed to study the general phenomenon of fragment distributions in PNSR with incident energies ranging from 100 to 1000 MeV.Considering the primary characteristics of PNSR,the SPAGINS formulas modify the EPAX and SPACS formulas and efficiently reproduce the measured data.The SPAGINS formulas provide a new and effective tool for predicting fragment production in PNSR. 展开更多
关键词 High-energy gamma-rays Spallation reaction Fragment cross-section empirical formula EPAX SPACS TALYS
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An Empirical Assessment and Analysis of the United Nations Convention on Contracts Judicial Applicability in China
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作者 Chen Sihan 《Contemporary Social Sciences》 2023年第6期53-74,共22页
Chinese domestic legislation on the judicial applicability of international treaties has been unsettled,especially under the Civil Code,which is silent on this issue.However,previous studies have depicted an image of ... Chinese domestic legislation on the judicial applicability of international treaties has been unsettled,especially under the Civil Code,which is silent on this issue.However,previous studies have depicted an image of a“pro-CISG”attitude in Chinese legal practice,which is distinguished from the tendency to circumvent the CISG in other jurisdictions such as the U.S.This contradictory phenomenon,namely the absence of guiding norms versus the embracement of the CISG in judicial practice,is rarely discussed,especially within the context of civil codification and recent external economic challenges.To verify this paradox,a manually collected dataset of 223 court decisions from 2013 to 2023 identifies some basic characteristics of the CISG judicial applicability in China,including the application rate,legal reasoning paths,citation frequencies of specific provisions,and some qualitative observations about the judicial behaviors in the international sales dispute resolution.The main finding is that Chinese courts have been applying the CISG at an obviously higher rate,compared with both their foreign counterparts and the general rate of applying foreign law in the international civil and commercial litigations in China.To explain this gap between“law in book”and“law in action,”the context of Chinese judicial practice should be considered.Despite the vagueness of domestic legislation,the judicial policy promotion,the innovative guiding cases system,the legal transplantation,and other factors may contribute to the“pro-CISG”attitude.As for the future promotion of CISG in the Chinese style of international commercial dispute resolution,these factors may coordinate with the legislative improvements. 展开更多
关键词 CISG China Judicial Applicability empirical Study
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Significant wave height forecasts integrating ensemble empirical mode decomposition with sequence-to-sequence model
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作者 Lina Wang Yu Cao +2 位作者 Xilin Deng Huitao Liu Changming Dong 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第10期54-66,共13页
As wave height is an important parameter in marine climate measurement,its accurate prediction is crucial in ocean engineering.It also plays an important role in marine disaster early warning and ship design,etc.Howev... As wave height is an important parameter in marine climate measurement,its accurate prediction is crucial in ocean engineering.It also plays an important role in marine disaster early warning and ship design,etc.However,challenges in the large demand for computing resources and the improvement of accuracy are currently encountered.To resolve the above mentioned problems,sequence-to-sequence deep learning model(Seq-to-Seq)is applied to intelligently explore the internal law between the continuous wave height data output by the model,so as to realize fast and accurate predictions on wave height data.Simultaneously,ensemble empirical mode decomposition(EEMD)is adopted to reduce the non-stationarity of wave height data and solve the problem of modal aliasing caused by empirical mode decomposition(EMD),and then improves the prediction accuracy.A significant wave height forecast method integrating EEMD with the Seq-to-Seq model(EEMD-Seq-to-Seq)is proposed in this paper,and the prediction models under different time spans are established.Compared with the long short-term memory model,the novel method demonstrates increased continuity for long-term prediction and reduces prediction errors.The experiments of wave height prediction on four buoys show that the EEMD-Seq-to-Seq algorithm effectively improves the prediction accuracy in short-term(3-h,6-h,12-h and 24-h forecast horizon)and long-term(48-h and 72-h forecast horizon)predictions. 展开更多
关键词 significant wave height wave forecasting ensemble empirical mode decomposition(EEMD) Seq-to-Seq long short-term memory
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Landslide displacement prediction based on optimized empirical mode decomposition and deep bidirectional long short-term memory network
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作者 ZHANG Ming-yue HAN Yang +1 位作者 YANG Ping WANG Cong-ling 《Journal of Mountain Science》 SCIE CSCD 2023年第3期637-656,共20页
There are two technical challenges in predicting slope deformation.The first one is the random displacement,which could not be decomposed and predicted by numerically resolving the observed accumulated displacement an... There are two technical challenges in predicting slope deformation.The first one is the random displacement,which could not be decomposed and predicted by numerically resolving the observed accumulated displacement and time series of a landslide.The second one is the dynamic evolution of a landslide,which could not be feasibly simulated simply by traditional prediction models.In this paper,a dynamic model of displacement prediction is introduced for composite landslides based on a combination of empirical mode decomposition with soft screening stop criteria(SSSC-EMD)and deep bidirectional long short-term memory(DBi-LSTM)neural network.In the proposed model,the time series analysis and SSSC-EMD are used to decompose the observed accumulated displacements of a slope into three components,viz.trend displacement,periodic displacement,and random displacement.Then,by analyzing the evolution pattern of a landslide and its key factors triggering landslides,appropriate influencing factors are selected for each displacement component,and DBi-LSTM neural network to carry out multi-datadriven dynamic prediction for each displacement component.An accumulated displacement prediction has been obtained by a summation of each component.For accuracy verification and engineering practicability of the model,field observations from two known landslides in China,the Xintan landslide and the Bazimen landslide were collected for comparison and evaluation.The case study verified that the model proposed in this paper can better characterize the"stepwise"deformation characteristics of a slope.As compared with long short-term memory(LSTM)neural network,support vector machine(SVM),and autoregressive integrated moving average(ARIMA)model,DBi-LSTM neural network has higher accuracy in predicting the periodic displacement of slope deformation,with the mean absolute percentage error reduced by 3.063%,14.913%,and 13.960%respectively,and the root mean square error reduced by 1.951 mm,8.954 mm and 7.790 mm respectively.Conclusively,this model not only has high prediction accuracy but also is more stable,which can provide new insight for practical landslide prevention and control engineering. 展开更多
关键词 Landslide displacement empirical mode decomposition Soft screening stop criteria Deep bidirectional long short-term memory neural network Xintan landslide Bazimen landslide
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Smoothed Empirical Likelihood Inference for Nonlinear Quantile Regression Models with Missing Response
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作者 Honghua Dong Xiuli Wang 《Open Journal of Applied Sciences》 2023年第6期921-933,共13页
In this paper, three smoothed empirical log-likelihood ratio functions for the parameters of nonlinear models with missing response are suggested. Under some regular conditions, the corresponding Wilks phenomena are o... In this paper, three smoothed empirical log-likelihood ratio functions for the parameters of nonlinear models with missing response are suggested. Under some regular conditions, the corresponding Wilks phenomena are obtained and the confidence regions for the parameter can be constructed easily. 展开更多
关键词 Nonlinear Model Quantile Regression Smoothed empirical Likelihood Missing at Random
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Empirical Likelihood Statistical Inference for Compound Poisson Vector Processes under Infinite Covariance Matrix
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作者 程从华 《Journal of Donghua University(English Edition)》 CAS 2023年第1期122-126,共5页
The paper discusses the statistical inference problem of the compound Poisson vector process(CPVP)in the domain of attraction of normal law but with infinite covariance matrix.The empirical likelihood(EL)method to con... The paper discusses the statistical inference problem of the compound Poisson vector process(CPVP)in the domain of attraction of normal law but with infinite covariance matrix.The empirical likelihood(EL)method to construct confidence regions for the mean vector has been proposed.It is a generalization from the finite second-order moments to the infinite second-order moments in the domain of attraction of normal law.The log-empirical likelihood ratio statistic for the average number of the CPVP converges to F distribution in distribution when the population is in the domain of attraction of normal law but has infinite covariance matrix.Some simulation results are proposed to illustrate the method of the paper. 展开更多
关键词 compound Poisson vector process(CPVP) infinite covariance matrix domain of attraction of normal law empirical likelihood(EL)
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Vehicle-Bridge Interaction Simulation and Damage Identification of a Bridge Using Responses Measured in a Passing Vehicle by Empirical Mode Decomposition Method
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作者 Shohel Rana Md. Rifat Zaman +2 位作者 Md. Ibrahim Islam Ifty Seyedali Mirmotalebi Tahsin Tareque 《Open Journal of Civil Engineering》 2023年第4期742-755,共14页
To prevent early bridge failures, effective Structural Health Monitoring (SHM) is vital. Vibration-based damage assessment is a powerful tool in this regard, as it relies on changes in a structure’s dynamic character... To prevent early bridge failures, effective Structural Health Monitoring (SHM) is vital. Vibration-based damage assessment is a powerful tool in this regard, as it relies on changes in a structure’s dynamic characteristics as it degrades. By measuring the vibration response of a bridge due to passing vehicles, this approach can identify potential structural damage. This dissertation introduces a novel technique grounded in Vehicle-Bridge Interaction (VBI) to evaluate bridge health. It aims to detect damage by analyzing the response of passing vehicles, taking into account VBI. The theoretical foundation of this method begins with representing the bridge’s superstructure using a Finite Element Model and employing a half-car dynamic model to simulate the vehicle with suspension. Two sets of motion equations, one for the bridge and one for the vehicle are generated using the Finite Element Method, mode superposition, and D’Alembert’s principle. The combined dynamics are solved using the Newmark-beta method, accounting for road surface roughness. A new approach for damage identification based on the response of passing vehicles is proposed. The response is theoretically composed of vehicle frequency, bridge natural frequency, and a pseudo-frequency component related to vehicle speed. The Empirical Mode Decomposition (EMD) method is applied to decompose the signal into its constituent parts, and damage detection relies on the Intrinsic Mode Functions (IMFs) corresponding to the vehicle speed component. This technique effectively identifies various damage scenarios considered in the study. 展开更多
关键词 Structural Health Monitoring Vibration-Based Damage Identification Vehicle-Bridge Interaction Finite Element Model empirical Mode Decomposition
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An Empirical Study on the Differences between Overt Translation and Covert Translation in Legal
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作者 Chunxu Qian 《Journal of Educational Theory and Management》 2023年第1期12-16,共5页
Currently,it is key to convey precise meanings to readers for translators.Observing expressing habits between different languages is the precondition to make target texts more readable.It is crucial to ensure the exac... Currently,it is key to convey precise meanings to readers for translators.Observing expressing habits between different languages is the precondition to make target texts more readable.It is crucial to ensure the exactness and seriousness of legal texts,but it does not mean that translators have to take machined way to leave out and even give up transmitting in-deep cultural implications for the intention of achieving the all-inclusive integrity of target content.It is a correct choice for translators to take overt translation and covert translation in line with traits of source language and target language and differences between civil law system and common law system.The intention of the article is to make an empirical study between overt translation and covert translation. 展开更多
关键词 Legal text Overt translation Covert translation READABILITY empirical study
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Physical Properties of the Function and Number of Empirical Macrohardness of the Material: Universal Physical Unit of Measurement of Macro Hardness (Part 2)
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作者 Shtyrov Nikolay 《Journal of Mechanics Engineering and Automation》 2023年第3期79-91,共13页
Results of analytical studies of the physical properties of the function and number of empirical macrohardness based on the standard experimental force diagram of kinetic macroindentation by a sphere.An analytical com... Results of analytical studies of the physical properties of the function and number of empirical macrohardness based on the standard experimental force diagram of kinetic macroindentation by a sphere.An analytical comparison method and a criterion for the similarity of the physical and empirical macrohardness of a material are proposed.The physical properties of the hardness measurement process using the Calvert-Johnson method are shown.The physical reasons for the size effect when measuring macrohardness are considered.The universal physical unit and standard of macrohardness of kinetic macroindentation by a sphere is substantiated. 展开更多
关键词 Physical theory of kinetic indentation method for determining the function and number of physical macrohardness ratio of empirical and physical macrohardness of a material universal physical unit of macrohardness.
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The Empirical Research of Native Thinking in the Process of English Composition
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作者 耿娟娟 贾颖 《疯狂英语(理论版)》 2016年第3期185-186,182,共3页
The method of questionnaire is employed to investigate the impact of Chinese thinking in the writing processes of 80 college English majors.It reveals that the English writing process is a bilingual event(namely,Engli... The method of questionnaire is employed to investigate the impact of Chinese thinking in the writing processes of 80 college English majors.It reveals that the English writing process is a bilingual event(namely,English writers have both Chinese and English at their disposal when they are composing in English).And no matter whether the English proficiency of the learners is high or low,the learners have a great dependence on Chinese thinking in the process of English writing.In the categories of task reacting and content organizing,there is no great difference between the high and low English proficiency students.But in the category of linguistic form,the influence of Chinese thinking on the low level students is far greater than the high level students. 展开更多
关键词 native thinking WRITING task reacting content organizing linguistic form empirical research
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An Empirical Study on the Concept of“Honesty and Integrity”between Chinese and Westerners
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作者 简耀 《海外英语》 2018年第18期188-190,共3页
Language and culture have been mutually dependent through their history. The moral principle—honesty and integrity isone of the most significant categories of human's culture.The author does a literary review of ... Language and culture have been mutually dependent through their history. The moral principle—honesty and integrity isone of the most significant categories of human's culture.The author does a literary review of the relationship between language andculture. Then she makes an analysis of an empirical study on Chinese and Western concepts of"honesty and integrity".In light ofthe empirical study, the author has found that Chinese mainly come into contact with the idea of"honesty and integrity"from theirparents, while the Westerners learn this concept mostly from school education. 展开更多
关键词 HONESTY and INTEGRITY empirical STUDY CONCEPT
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An Empirical Research on Integrating Chinese Traditional Culture into College English Teaching
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作者 时俊霞 《海外英语》 2017年第21期230-231,共2页
198 non-English freshmen students from Shandong Yingcai College were selected as research subjects.The subjects were divided into the experimental group(EG) and the control group(CG).The students in EG were taught Eng... 198 non-English freshmen students from Shandong Yingcai College were selected as research subjects.The subjects were divided into the experimental group(EG) and the control group(CG).The students in EG were taught English integrated Chinese traditional culture for three semesters,while the ones in CG were taught as usual.The results indicate that the integration of Chinese culture broadens the students' horizons and improves the students' ability to express Chinese culture in English and intercultural communicative competence. 展开更多
关键词 Chinese culture College English teaching English expressive ability empirical research
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政府科技资助能够提高企业的R&D投入吗?——读Empirical Development Economics
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作者 何彬 范硕 《公共管理评论》 CSSCI 2018年第2期117-128,共12页
科技创新是一个国家提高生产力和综合国力的重要支撑。中国在创新型国家建设的道路上,如何不断提高企业R&D投入是一个极为重要的问题。是否能够利用政府科技资助提高企业R&D投入?关于这个问题的解答,对于今后中国调整安排政府... 科技创新是一个国家提高生产力和综合国力的重要支撑。中国在创新型国家建设的道路上,如何不断提高企业R&D投入是一个极为重要的问题。是否能够利用政府科技资助提高企业R&D投入?关于这个问题的解答,对于今后中国调整安排政府科技资助的方向、结构、模式都具有重要的意义。学术界广泛利用各种层面的数据(截面数据、时序数据、面板数据)进行研究,获得了丰富的成果。但是目前还没有得到一致的研究结论。随着可资利用的中国宏观高频数据和企业微观数据的日益增多,进一步从时频的角度分析政府科技资助对企业R&D投入的影响是一个具有潜力的研究方向。另外学术界还应该广泛利用微观计量分析工具对政府科技资助与企业R&D投入的因果影响特征进行稳健、有效的检验。 展开更多
关键词 政府科技资助 企业R&D投入 经验研究方法
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Regional features of the temperature trend in China based on Empirical Mode Decomposition 被引量:8
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作者 SUN Xian LIN Zhenshan +1 位作者 CHENG Xiaoxia JIANG Chuangye 《Journal of Geographical Sciences》 SCIE CSCD 2008年第2期166-176,共11页
By the Empirical Mode Decomposition method, we analyzed the observed monthly average temperature in more than 700 stations from 1951-2001 over China. Simultaneously, the temperature variability of each station is calc... By the Empirical Mode Decomposition method, we analyzed the observed monthly average temperature in more than 700 stations from 1951-2001 over China. Simultaneously, the temperature variability of each station is calculated by this method, and classification chart of long term trend and temperature variability distributing chart of China are obtained, supported by GIS, 1 kmxl km resolution. The results show that: in recent 50 years, the temperature has increased by more than 0.4~C/10a in most parts of northern China, while in Southwest China and the middle and lower Yangtze Valley, the increase is not significant. The areas with a negative temperature change rate are distributed sporadically in Southwest China. Meanwhile, the temperature data from 1881 to 2001 in nine study regions in China are also analyzed, indicating that in the past 100 years, the temperature has been increasing all the way in Northeast China, North China, South China, Northwest China and Xinjiang and declining in Southwest China. An inverse ‘V-shaped’ trend is also found in Central China. But in Tibet the change is less significant. 展开更多
关键词 China TEMPERATURE empirical mode decomposition intrinsic mode function
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A New Method of Wind Turbine Bearing Fault Diagnosis Based on Multi-Masking Empirical Mode Decomposition and Fuzzy C-Means Clustering 被引量:8
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作者 Yongtao Hu Shuqing Zhang +3 位作者 Anqi Jiang Liguo Zhang Wanlu Jiang Junfeng Li 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2019年第3期156-167,共12页
Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and ... Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and timely. First, FCM clustering is employed to classify the data into different clusters, which helps to estimate whether there is a fault and how many fault types there are. If fault signals exist, the fault vibration signals are then demodulated and decomposed into different frequency bands by MMEMD in order to be analyzed further. In order to overcome the mode mixing defect of empirical mode decomposition (EMD), a novel method called MMEMD is proposed. It is an improvement to masking empirical mode decomposition (MEMD). By adding multi-masking signals to the signals to be decomposed in different levels, it can restrain low-frequency components from mixing in highfrequency components effectively in the sifting process and then suppress the mode mixing. It has the advantages of easy implementation and strong ability of suppressing modal mixing. The fault type is determined by Hilbert envelope finally. The results of simulation signal decomposition showed the high performance of MMEMD. Experiments of bearing fault diagnosis in wind turbine bearing fault diagnosis proved the validity and high accuracy of the new method. 展开更多
关键词 Wind TURBINE BEARING FAULTS diagnosis Multi-masking empirical mode decomposition (MMEMD) Fuzzy c-mean (FCM) clustering
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