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数学教学课堂提问的现状及对策 被引量:15
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作者 李红 《教学与管理(中学版)》 2001年第4期52-54,共3页
关键词 课堂提问 数学教学 师生双边活动 学生思维 思维活动 “时间差” 现状 课堂教学效率
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免费教材:无回款挪用“远虑” 却有结算延滞“近忧”
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作者 穆宏志 《编辑之友》 CSSCI 北大核心 2009年第2期15-16,共2页
随着政府统一采购、免费发放的教材比例逐步扩大,教材编印发供的链条运转正发生着新变化——教材配套率的提高,一定程度上扩大了某些教材的使用量,回款也更有保障,这对倚重教材发行的新华系统来说,无疑是利好消息。但新华书店也遇... 随着政府统一采购、免费发放的教材比例逐步扩大,教材编印发供的链条运转正发生着新变化——教材配套率的提高,一定程度上扩大了某些教材的使用量,回款也更有保障,这对倚重教材发行的新华系统来说,无疑是利好消息。但新华书店也遇到了新问题,这就是从过去到学校收款一级级上交,改为现在由财政一级级向下拨款。然而,一些省份的回款时间相比过去要晚,造成“时间差”,使发行单位资金链紧张,现金流面临严峻问题,继而引发新华书店无法给出版社回款,出版社又拖欠印刷厂的连锁反应。 展开更多
关键词 教材发行 回款 免费 “时间差” 延滞 结算 新华书店 统一采购
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Extracting useful high-frequency information from wide-field electromagnetic data using time-domain signal reconstruction 被引量:1
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作者 LING Fan YANG Yang +6 位作者 LI Gang ZHOU Chang-yu HUANG Min WANG Xin ZHANG Heng ZHU Yu-zhen SUN Huai-feng 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第11期3767-3778,共12页
The wide-field electromagnetic method is widely used in hydrocarbon exploration,mineral deposit detection,and geological disaster prediction.However,apparent resistivity and normalized field amplitude exceeding 2048 H... The wide-field electromagnetic method is widely used in hydrocarbon exploration,mineral deposit detection,and geological disaster prediction.However,apparent resistivity and normalized field amplitude exceeding 2048 Hz often exhibit upward warping in data,making geophysical inversion and interpretation challenging.The cumulative error of the crystal oscillator in signal transmission and acquisition contributes to an upturned apparent resistivity curve.To address this,a high-frequency information extraction method is proposed based on time-domain signal reconstruction,which helps to record a complete current data sequence;moreover,it helps estimate the crystal oscillator error for the transmitted signal.Considering the recorded error,a received signal was corrected using a set of reconstruction algorithms.After processing,the high-frequency component of the wide-field electromagnetic data was not upturned,while accurate high-frequency information was extracted from the signal.Therefore,the proposed method helped effectively extract high-frequency components of all wide-field electromagnetic data. 展开更多
关键词 wide-field electromagnetic method crystal oscillator error time series signal resampling signal reconstruction
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Iterative identification of discrete-time output-error model with time delay 被引量:3
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作者 CHEN Feng-wei LIU Tao 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第3期647-654,共8页
The problem of discrete-time model identification of industrial processes with time delay was investigated.An iterative and separable method is proposed to solve this problem,that is,the rational transfer function mod... The problem of discrete-time model identification of industrial processes with time delay was investigated.An iterative and separable method is proposed to solve this problem,that is,the rational transfer function model parameters and time delay are alternately fixed to estimate each other.The instrumental variable technique is applied to guarantee consistent estimation against measurement noise.A noteworthy merit of the proposed method is that it can handle fractional time delay estimation,compared to existing methods commonly assuming that the time delay is an integer multiple of the sampling interval.The identifiability analysis for time delay is addressed and correspondingly,some guidelines are provided for practical implementation of the proposed method.Numerical and experimental examples are presented to illustrate the effectiveness of the proposed method. 展开更多
关键词 system identification output-error model instrumental variable method time delay
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Finite difference time domain method forward simulation of complex geoelectricity ground penetrating radar model 被引量:5
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作者 戴前伟 冯德山 何继善 《Journal of Central South University of Technology》 EI 2005年第4期478-482,共5页
The ground penetrating radar(GPR) forward simulation all aims at the singular and regular models, such as sandwich model, round cavity, square cavity, and so on, which are comparably simple. But as to the forward of c... The ground penetrating radar(GPR) forward simulation all aims at the singular and regular models, such as sandwich model, round cavity, square cavity, and so on, which are comparably simple. But as to the forward of curl interface underground or “v” figure complex model, it is difficult to realize. So it is important to forward the complex geoelectricity model. This paper takes two Maxwell’s vorticity equations as departure point, makes use of the principles of Yee’s space grid model theory and the basic principle finite difference time domain method, and deduces a GPR forward system of equation of two dimensional spaces. The Mur super absorbed boundary condition is adopted to solve the super strong reflection on the interceptive boundary when there is the forward simulation. And a self-made program is used to process forward simulation to two typical geoelectricity model. 展开更多
关键词 ground penetrating radar finite difference time domain method forward simulation ideal frequency dispersion relationship
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Slope displacement prediction based on morphological filtering 被引量:4
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作者 李启月 许杰 +1 位作者 王卫华 范作鹏 《Journal of Central South University》 SCIE EI CAS 2013年第6期1724-1730,共7页
Combining mathematical morphology (MM),nonparametric and nonlinear model,a novel approach for predicting slope displacement was developed to improve the prediction accuracy.A parallel-composed morphological filter wit... Combining mathematical morphology (MM),nonparametric and nonlinear model,a novel approach for predicting slope displacement was developed to improve the prediction accuracy.A parallel-composed morphological filter with multiple structure elements was designed to process measured displacement time series with adaptive multi-scale decoupling.Whereafter,functional-coefficient auto regressive (FAR) models were established for the random subsequences.Meanwhile,the trend subsequence was processed by least squares support vector machine (LSSVM) algorithm.Finally,extrapolation results obtained were superposed to get the ultimate prediction result.Case study and comparative analysis demonstrate that the presented method can optimize training samples and show a good nonlinear predicting performance with low risk of choosing wrong algorithms.Mean absolute percentage error (MAPE) and root mean square error (RMSE) of the MM-FAR&LSSVM predicting results are as low as 1.670% and 0.172 mm,respectively,which means that the prediction accuracy are improved significantly. 展开更多
关键词 slope displacement prediction parallel-composed morphological filter functional-coefficient auto regressive predictionaccuracy
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Efficient fast mode decision using mode complexity for multi-view video coding 被引量:1
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作者 王凤随 沈庆宏 都思丹 《Journal of Central South University》 SCIE EI CAS 2014年第11期4244-4253,共10页
The variable block-size motion estimation(ME) and disparity estimation(DE) are adopted in multi-view video coding(MVC) to achieve high coding efficiency. However, much higher computational complexity is also introduce... The variable block-size motion estimation(ME) and disparity estimation(DE) are adopted in multi-view video coding(MVC) to achieve high coding efficiency. However, much higher computational complexity is also introduced in coding system, which hinders practical application of MVC. An efficient fast mode decision method using mode complexity is proposed to reduce the computational complexity. In the proposed method, mode complexity is firstly computed by using the spatial, temporal and inter-view correlation between the current macroblock(MB) and its neighboring MBs. Based on the observation that direct mode is highly possible to be the optimal mode, mode complexity is always checked in advance whether it is below a predefined threshold for providing an efficient early termination opportunity. If this early termination condition is not met, three mode types for the MBs are classified according to the value of mode complexity, i.e., simple mode, medium mode and complex mode, to speed up the encoding process by reducing the number of the variable block modes required to be checked. Furthermore, for simple and medium mode region, the rate distortion(RD) cost of mode 16×16 in the temporal prediction direction is compared with that of the disparity prediction direction, to determine in advance whether the optimal prediction direction is in the temporal prediction direction or not, for skipping unnecessary disparity estimation. Experimental results show that the proposed method is able to significantly reduce the computational load by 78.79% and the total bit rate by 0.07% on average, while only incurring a negligible loss of PSNR(about 0.04 d B on average), compared with the full mode decision(FMD) in the reference software of MVC. 展开更多
关键词 multi-view video coding mode decision mode complexity computational complexity
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A new single degree-of-freedom resonance device 被引量:2
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作者 高改梨 《Journal of Central South University》 SCIE EI CAS 2012年第10期2782-2787,共6页
A new single degree-of-freedom (1 DOF) resonance device was developed. It mainly comprises a linear motor, a vibrating screen, a supporting spring set, a supporting frame and a damper set. Forces acting on the vibra... A new single degree-of-freedom (1 DOF) resonance device was developed. It mainly comprises a linear motor, a vibrating screen, a supporting spring set, a supporting frame and a damper set. Forces acting on the vibrating screen were found. A differential equation for describing the forces was set up. Equations that were used to evaluate the exciting force and exciting frequency in resonance were derived from the solution to the differential equation. In addition, an equation for evaluating the deformed magnitude of the damping springs in the damper set was presented so that the suitable damping may be obtained. Finally, a Matlab/Simulink model of the new i DOF resonance device was also built. Displacement-time curves of the vibrating screen under four conditions were obtained in the use of the Matlab/Simulink simulation. The curves indicate that it can shorten the time for the vibrating screen to be into the stable resonance with increasing the damping, and it can lengthen the time with increasing the vibrated mass or amplitude, but every given angular frequency cannot acquire the desired amplitude value of resonance. 展开更多
关键词 vibrating screen single degree-of-freedom RESONANCE dynamics analysis
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Predication of plasma concentration of remifentanil based on Elman neural network 被引量:1
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作者 汤井田 曹扬 +1 位作者 肖嘉莹 郭曲练 《Journal of Central South University》 SCIE EI CAS 2013年第11期3187-3192,共6页
Due to the nature of ultra-short-acting opioid remifentanil of high time-varying,complex compartment model and low-accuracy of plasma concentration prediction,the traditional estimation method of population pharmacoki... Due to the nature of ultra-short-acting opioid remifentanil of high time-varying,complex compartment model and low-accuracy of plasma concentration prediction,the traditional estimation method of population pharmacokinetics parameters,nonlinear mixed effects model(NONMEM),has the abuses of tedious work and plenty of man-made jamming factors.The Elman feedback neural network was built.The relationships between the patients’plasma concentration of remifentanil and time,patient’age,gender,lean body mass,height,body surface area,sampling time,total dose,and injection rate through network training were obtained to predict the plasma concentration of remifentanil,and after that,it was compared with the results of NONMEM algorithm.In conclusion,the average error of Elman network is 6.34%,while that of NONMEM is 18.99%.The absolute average error of Elman network is 27.07%,while that of NONMEM is 38.09%.The experimental results indicate that Elman neural network could predict the plasma concentration of remifentanil rapidly and stably,with high accuracy and low error.For the characteristics of simple principle and fast computing speed,this method is suitable to data analysis of short-acting anesthesia drug population pharmacokinetic and pharmacodynamics. 展开更多
关键词 Elman neural network REMIFENTANIL plasma concentration predication model
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