茶叶功效成分的提取及均方分析

茶叶的主要成分为嘌呤类生物碱和茶多酚，以它们的理化性质为基础，提出了影响提取率的几个因素，并进行均方分析从而达到较为理想的结果。

一种基于均方偏差分析的通用最小均方算法

无论是传统的定步长还是最近新提出的变步长最小均方(LMS)算法,在处理特定数学特征的信号时需要对算法参数进行先验的估计才能达到较好的效果。但在实际信号处理过程中,算法参数的估计本就是一个很困难的过程。该文分析了LMS算法的均方偏差及收敛特性,并提出一种以相对误差为变量的变步长LMS算法,能够实现步长控制参数的自估计;可以自适应不同数学特征的信号,具体算例表明新算法有更快的收敛速度和较小的均方误差。

基于q梯度的仿射投影算法及其稳态均方收敛分析

q梯度是基于q微分的广义梯度。为了进一步提高仿射投影算法(APA)的滤波性能,该文基于最小均方误差准则将q梯度应用于APA进而产生一种新的q-APA,在高斯噪声环境下选择合适的q值可以取得理想的滤波性能。通过理论分析,提出了保证算法收敛的充分条件,并计算出表征滤波性能的稳态额外均方误差(EMSE)。除此之外,为了进一步提高算法的滤波性能,提出一个变q的APA(V-q-APA)。在高斯噪声环境下,将q-APA和V-q-APA应用于系统辨识中。仿真结果表明:与传统的APA和变q的最小化均方(V-q-LMS)算法相比,q-APA和V-q-APA均具有更好的滤波性能。

基于梯度下降VAD方法的风场探测技术

为了获得高精度矢量风速,着重对激光雷达回波信号数据反演方法进行分析研究。开展了一系列1.55μm全光纤相干测风激光雷达测速实验,采用基于梯度下降的VAD(Velocity-Azimuth Display,速度方位显示)风场反演算法进行矢量风场的反演,并通过MATLAB编程与仿真进行分析。基于模拟数据进行仿真实验,以风场反演结果的均方误差(MSE)为评价指标,对比LM最小二乘算法、Newton-Gaussian(NG)最小二乘算法及梯度下降算法这3种风场反演算法在进行不同迭代次数下的均方误差。结果表明,梯度下降和LM最小二乘算法最终都能收敛且MSE值较小,但LM最小二乘算法受初值影响较大,所以选取梯度下降算法进行风场反演成为更优选择。

混合噪声中非线性RLS算法的性能分析

本文给出了在混合噪声中非线性递归最小均方误差算法的性能分析 .该算法即是非线性RLS(NRLS) .对残差的饱和处理使用了广义限幅函数 .提出了改进的NRLS均方分析 .计算机数值模拟表明理论分析与模拟结果符合得很好 .根据该分析 ,可以将NRLS的收敛和均方误差表示为非线性函数的斜率和限幅水平的函数 .基于归一化的均方误差 (mse) ,引入了一个辅助变量 ,导出了时变限幅函数 ,加速了收敛并且得到了更小的均方误差 .

RLS算法的改进性能分析(英文)

讨论了递归最小均方误差算法 (RLS)的性能分析 .对该算法误差的均值及方差都进行了研究 .在平均原理基础上使用了更精确的处理方法 ,得到一种改进的性能分析方法 .新的分析方法得到的理论值更接近模拟的结果 ,优于通常方法的结果 .

多任务业务外包的激励契约

多任务业务外包有助于发包企业充分利用外部资源.通过设计面向多任务的激励契约,平衡接包企业在各项任务之间的投入,能够改善外包效率.运用均方效用函数方法,构建了多任务委托代理模型,通过敏感性分析讨论了外生参数的变化对激励契约的影响,并在任务无关、互补和替代三种情形下考察了模型的应用.研究发现对特定任务的激励,不仅受到接包企业风险偏好和与此任务有关的参数变化的影响,还受到与其它任务有关的参数变化的影响,其中影响的方向和强度分别依赖于任务之间的关联属性和关联程度.研究结论为发包企业利用各种属性指标,尤其是任务关联性质,加强对多任务外包的激励管理具有借鉴意义.

Numerical simulation of calm water entry of flatted-bottom seafloor mining tool

The hydrodynamic problem of a two-dimensional model of seafloor mining tool entering still water vertically at constant speed was analyzed based on the velocity potential theory. For the assumption that the water entry occurs with very short time interval, the viscosity and gravity of fluid were neglected. Considering the characteristic shape of it, the seafloor mining tool was simplified as a flat-bottom body. The governing equations were the Reynolds time-averaged equations and the k-e model. Finite element analysis was undertaken using the CFD software, Fluent. The impact pressures on the bottom of the mining tool were computed based on the improved volume of fuid method （VOF）. The pressure distribution, the maximum impact pressure, and the impact duration time during the water entry of mining tool are presented at various deploying velocities, the two peak pressures in the impact process are observed, and the relationship between the maximum impact pressure and the deploying velocity is obtained. The results are compared with those based on other prediction theories and methods.

A Quantized Kernel Least Mean Square Scheme with Entropy-Guided Learning for Intelligent Data Analysis

Quantized kernel least mean square(QKLMS) algorithm is an effective nonlinear adaptive online learning algorithm with good performance in constraining the growth of network size through the use of quantization for input space. It can serve as a powerful tool to perform complex computing for network service and application. With the purpose of compressing the input to further improve learning performance, this article proposes a novel QKLMS with entropy-guided learning, called EQ-KLMS. Under the consecutive square entropy learning framework, the basic idea of entropy-guided learning technique is to measure the uncertainty of the input vectors used for QKLMS, and delete those data with larger uncertainty, which are insignificant or easy to cause learning errors. Then, the dataset is compressed. Consequently, by using square entropy, the learning performance of proposed EQ-KLMS is improved with high precision and low computational cost. The proposed EQ-KLMS is validated using a weather-related dataset, and the results demonstrate the desirable performance of our scheme.

Prediction of representative deformation modulus of longwall panel roof rock strata using Mamdani fuzzy system

Deformation modulus is the important parameter in stability analysis of tunnels, dams and mining struc- tures. In this paper, two predictive models including Mamdani fuzzy system （MFS） and multivariable regression analysis （MVRA） were developed to predict deformation modulus based on data obtained from dilatometer tests carried out in Bakhtiary dam site and additional data collected from longwall coal mines. Models inputs were considered to be rock quality designation, overburden height, weathering, unconfined compressive strength, bedding inclination to core axis, joint roughness coefficient and fill thickness. To control the models performance, calculating indices such as root mean square error （RMSE）, variance account for （VAF） and determination coefficient （R^2） were used. The MFS results show the significant prediction accuracy along with high performance compared to MVRA results. Finally, the sensitivity analysis of MFS results shows that the most and the least effective parameters on deformation modulus are weatherin~ and overburden height, respectively.

Preparation and Unimolecular-Micellization Behavior of Homopolymer of Surface-Active Monomer AMC14AB

（2-acrylamido） ethyl tetradecyl dimethylammonium bromide （AMC14AB） was polymerized in aqueous solu- tion to form the homopolymer P（AMC14AB）. The physicochemical properties of P（AMC14AB） in aqueous solution were mainly studied with fluorescent probe method, surface tension measurement and conductom- etry. The experimental results show that the aggregation morphology of P（AMC14AB） in aqueous solution is unimolecular micelle as expected. Being different from conventional multimolecular micelle systems, the unimolecular micelle system of P（AMC14AB） not only shows critical micellar concentration （CMC=0）, （i.e. once added to pure water, the surface tension decreases immediately in spite how small the density is）, but also the surface tension stays almost the same with the concentration increasing. That is to say, there is no mutational point on the relationship curve between surface tension and concentration. Furthermore, the unimolecular micelle system of P（AMC14AB） has no Krafft temperature, i.e. at any temperature, so long as it is dissolved in water, the unimolecular micelles will form. Besides this, for the solubilization of hydrophobic organic substances, the unimolecular micelle system of P（AMC14AB） is obviously different from the common multimolecular micelle system, having no turning point on the relationship curve between toluene solubi- lizaion amount and P（AMC14AB） concentration, and the solubilizing ability of the unimolecular-micelle system of P（AMC14AB） for hydrophobic organic substances is much higher than that of the conventional multimolecular micelle solutions of common surfactants, such as centyl trimethyl ammonium bromide.

The Study of the Effect of Educational Level of Students and English Language Teachers＇ Awareness on True and False Cognates in Iran

The ability to speak two languages in the non-English-speaking countries is a remarkable achievement. There is a good reason to believe that bilingualism is the norm for the majority of people in the world, because 70% of the earth＇s population are supposed to be bilingual or multilingual. Our purpose of the study was to determine the participants＇ awareness of using true and false cognate words of L 1 （the first language） ＆ L2 （the second language） in learning English. Three hundred and eighty-five selected people from 3,789 statistical population participated in 2014--2015 at three levels of A.D., B.A., and M.A. of Islamic Azad University as well as teachers of English in English educational institutions in Zanjan （Iran）. Each educational level was considered as one category with the total sample calculated by using Kokran Formula, and the amount of each category was determined by using appropriate proportion and randomized categorical sampling method. The participants＇ age was between from 18 to 52, with a mean age of 29 years. The materials were 45 words of true and false cognate＇s words from 500 words by doing CVR （content validity ratio） and CVI （content validity index） （Lawshe＇s table with the index of 88% and 82% respectively） for being reliable and valid. ANOVA （Analysis of variance） was used for studying the effect of educational level on the rate of awareness. In other words, the awareness level has been compared in different educational levels. The results of Dankan test show that： There is no significant difference between the awareness of A.D., B.A., and M.A. levels, but there is a significant difference between the level of awareness of teachers group and the other groups （in true cognate words） and for false cognate words, there is no significant difference between the level of awareness of the four groups in this regard.

Ensemble Simulations of a Nonlinear Barotropic Model for the North Atlantic Oscillation

A numerical ensemble-mean approach was employed to solve a nonlinear barotropic model with chastic basic flows to analyze the nonlinear effects in the formation of the North Atlantic Oscillation （NAO）. The nonlinear response to external forcing was more similar to the NAO mode than the linear response was, indicating the importance of nonlinearity. With increasing external forcing and enhanced low-frequency anomalies, the effect of nonlinearity increased. Therefore, for strong NAO events, nonlinearity should be considered.

Different Criteria for the Optimal Number of Clusters and Selection of Variables with R

One of the most important problems of clustering is to define the number of classes. In fact, it is not easy to find an appropriate method to measure whether the cluster configuration is acceptable or not. In this paper we propose a possible and non-automatic solution considering different criteria of clustering and comparing their results. In this way robust structures of an analyzed dataset can be often caught （or established） and an optimal cluster configuration, which presents a meaningful association, may be defined. In particular, we also focus on the variables which may be used in cluster analysis. In fact, variables which contain little clustering information can cause misleading and not-robustness results. Therefore, three algorithms are employed in this study： K-means partitioning methods, Partitioning Around Medoids （PAM） and the Heuristic Identification of Noisy Variables （HINoV）. The results are compared with robust methods ones.

Joint Transceiver Design for OFDM Systems

Orthogonal Frequency Division Multiplexing(OFDM) is an effective technique to deal with a frequency selective channel since it can convert the channel into some flat fading subchannels.However,very different output SNR values of the subchannels will lead to poor bit error performance when a linear equalizer and Equal Bit Allocation(EBA) are adopted in OFDM systems.So,we proposed three novel nonlinear Joint Transceiver(JT) schemes based on Zero-Forcing(ZF) criterion and Minimum Mean Square Error(MMSE) criterion respectively,which can transform all subchannels of an OFDM system into subchannels with identical channel gain.Thus,EBA is equivalent to the Optimum Bit Allocation(OBA) for these subchannels.Numerical analysis helps us to obtain the theoretical approximate BER values of the JT scheme.Simulation results verify the numerical analysis and confirm that the performance of our proposed JT scheme greatly outperforms the traditional linear equalizer with EBA at moderate and high SNR values.

Adaptive Rate Control Scheme for H.264/AVC

The purpose of this paper is to improve allocation of the number of bits without skipping the frame by accurately estimating the target bits in H. 264/AVC rate control. The scheme ImPoses an enhancement method of the target frame rate based on H. 264/AVC bit allocation. The enhancement uses a frame complexion estimation to improve the existing Mean Absolute Difference （MAD） complexity measurement. Bit allocation to each frame is not just computed by target frame rote but also adjusted by a combined frame complexity measure. Using the statistical characteristic, the scheme obtains change of occurrence bit about QP to apply the bit amount by QP from the video characteristic and apply it in the estimated bit amount of the current frame. Simulation results show that the proposed rate eontrol scheme achieves time saving of mine than 99% over existing rate control algorithm. Nevertheless, Peak Signal-to-Noise Ration （PSNR） and bit rate were almost the same as the performances.

有相位差非平稳随机激励下系统的响应

线性系统在有相位差非平稳随机激励下的响应是工程研究中十分有意义的问题。本文在用有限元离散建立系统方程的基础上，在状态空间应用复模态理论推导了线性系统受非平稳随机激励的位移的均方响应，且给出了减缩模态准确地处理非经典阻尼的计算形式和多相位调制白噪声激励下的系统相关响应的解析表达式。该方法可以方便地处理桥梁结构或其它结构的集中阻尼问题。对比算例表明，在工程设计中考虑相位差的影响是十分必要的。

Assessment of air temperatures from different meteorological reanalyses for the East Antarctic region between Zhongshan and Dome A

The accuracy of daily mean 2 meter air temperatures from five reanalyses are assessed against in-situ observations from Automatic Weather Stations in East Antarctica for 2005 to 2008. The five reanalyses all explain more than 70% of the average variance, and have annual root mean square errors （RMSE） between 3.4 and 6.9℃. The NOAA reanalyses, NCEP-1, NCEP-2 and 20CRv2, have cool biases of 2.5, 1.4 and 1.5℃, respectively. The ERA Interim and JCDAS reanalyses have warm biases of 1.7 and 2.0℃. All reanalyses generally perform better in the austral spring and worse in winter and autumn. They also show the best performance at an inland plateau site at 2800 m elevation, but are worst at Dome A, the summit of the East Antarctic ice sheet. In general, ERA Interim is superior to the other reanalyses, probably because of its 4D assimilation scheme. The three NOAA reanalyses perform worst; Their assimilation scheme is more constrained by limited observations and 20CRy2 has less input data, assimilating only surface pressure observations. Despite deficiencies and limitations, the reanalyses are still powerful tools for climate studies in the Antarctic region. However, more in-situ observations are required, especially from the vast interior of Antarctica.

Improved simulation method for urban free-space optical links based on the finite Markov state model

An improved method is proposed to simulate the scintillation introduced by the turbulence, based on the finite Markov state model. As a contrast to the literatures, uniformly distributed variables take place during a certain state, which contributes to equivalent simulation of the intensity fluctuations with fewer states than the traditional Markov model. It's also discovered that the proposed Markov model with 20 states provides a satisfactory approximation to the experimental results in the auto-covariance analysis. Moreover, the outage probability and mean fading time are more accurate than those of the traditional Markov model with equivalent states.

Statistical analysis of vibration and sound radiation of submerged stiffened rectangular plates

In order to extend the statistical energy analysis(SEA) method to predict the vibration and sound radiation of underwater structures,we mainly analyze the effect of water loading on the key parameters in SEA and propose the approximate expressions of modal density and mean square velocity of submerged plates.With the radiation efficiency of submerged plates previously proposed by us,the modified SEA solutions of the radiated sound power and mean square velocity of submerged stiffened rectangular plates are established.Numerical examples show that the modified SEA solutions are more close to the theoretical solutions than the present SEA solutions,and reflect the mean value or trend of the theoretical solution much better,especially at lower frequencies.An experiment of point-exciting submerged plates was done in a lake.The experiment values show that for both un-stiffened and stiffened plates,the modified SEA solutions have a good agreement while the present SEA solution has considerable error,which validates the established statistical model.