具有对数-指数参数特征的螺旋曲面参数化精确造型

对参数中含有对数-指数的新型螺旋曲面进行质点的成形运动学分析和描述,依据质点成形运动组合系统化定义和分类新螺旋曲面,以揭示此型螺旋曲面几何特征、数学性质、工程应用可能及推测新型螺旋曲面.构建具有对应具有对数-指数参数特征的螺旋曲线数学模型,应用Pro/E二次开发工具Pro/TOOLKIT,修正的螺旋曲面扫描算法和参数传递原理构建单一全关联数据库.对整个模型任意点,任意特征数字信息的提取实现了该类螺旋曲面的精确参数化造型.该参数化模型中对应具有对数-指数参数特征的螺旋曲线生成直接来自数学模型,所构建的参数化模型理论上无任何误差.

n个正数的算术——指数——对数——几何平均不等式(英文)

对两个正数的指数平均和对数平均进行了推广 ,得到了n个正数的指数平均和对数平均。

Effects of RapidEye Imagery's Red-edge Band and Vegetation Indices on Land Cover Classification in an Arid Region

Land cover classification(LCC) in arid regions is of great significance to the assessment, prediction, and management of land desertification. Some studies have shown that the red-edge band of RapidE ye images was effective for vegetation identification and could improve LCC accuracy. However, there has been no investigation of the effects of RapidE ye images' red-edge band and vegetation indices on LCC in arid regions where there are spectrally similar land covers mixed with very high or low vegetation coverage information and bare land. This study focused on a typical inland arid desert region located in Dunhuang Basin of northwestern China. First, five feature sets including or excluding the red-edge band and vegetation indices were constructed. Then, a land cover classification system involving plant communities was developed. Finally, random forest algorithm-based models with different feature sets were utilized for LCC. The conclusions drawn were as follows: 1) the red-edge band showed slight contribution to LCC accuracy; 2) vegetation indices had a significant positive effect on LCC; 3) simultaneous addition of the red-edge band and vegetation indices achieved a significant overall accuracy improvement(3.46% from 86.67%). In general, vegetation indices had larger effect than the red-edge band, and simultaneous addition of them significantly increased the accuracy of LCC in arid regions.

Large Deviations for Sums of Heavy-tailed Random Variables

This paper is a further investigation of large deviations for sums of random variables Sn=i=1∑n Xi and S（t）=i=1∑N（t）Xi,（t≥0）, where {X_n,n≥1） are independent identically distribution and non-negative random variables, and {N（t）,t≥0} is a counting process of non-negative integer-valued random variables, independent of {X_n,n≥1}. In this paper, under the suppose F∈G, which is a bigger heavy-tailed class than C, proved large deviation results for sums of random variables.

关于雾天遥感图像增强准确性优化研究

遥感图像在接收和传输过程中,不可避免地会产生降质,在雾天采集的遥感图像,图像质量更差。传统的图像增强算法存在过增现象,例如直方图均衡化会强制图像的直方图分布服从均匀分布,从而导致增强过度。因此提出一种应用对数一指数运算的修正直方图均衡的方法。将原始图像直方图乘以其均值后,取对数一指数变换对,使其自适应地平滑图像的直方图的同时,近似保持平滑前的直方图。最后,用累计分布函数进行查找表的直方图均衡化操作,得到最终的增强遥感图像。实验结果表明,增强后的图像,视觉效果得到明显的改善,且不会产生伪影、过增和不自然的现象。同时,创新技术能提高运算速度,使其有益于遥感图像的实时处理。

Combined Selection Index for New Yorkshire Dam Line with High Prolificacy

The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /：2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two main selected traits such as total number of born and age at 100 kg weight was 12.17 piglets/litter and 165.18 d, respectively. The genetic improvements per generates was 0.156 and -2.198, respec- tively. The breeding objects of the new Yorkshire dam line with high prolificacy were basically reached. It indicated that the methods and index could be used in pig breeding.

有界整规划中的渐近强非线性对偶

本文提出了一种整数规划中的指数一对数对偶.证明了此指数-对数对偶方法具有的渐近强对偶性质,并提出了不需要进行对偶搜索来解原整数规划问题的方法.特别地,当选取合适的参数和对偶变量时,原整数规划问题的解可以通过解一个非线性松弛问题来得到.对具有整系数目标函数及约束函数的多项式整规划问题,给出了参数及对偶变量的取法.

基于改进GM(1,1)模型的引信系统贮存寿命预测方法

针对引信系统复杂、贮存样本量受限、测试数据波动性较大等问题,提出了基于改进GM(1,1)模型的引信系统贮存寿命预测方法。该方法在利用"指数-对数变换"对原始数据预先进行光滑处理的基础上,通过建立GM(1,1)模型和残差修正模型,推导出对引信系统贮存寿命预测的改进算法。实例分析表明,该方法具有预测精度高、适用范围广、通用性强等优点,可推广用于类似系统或设备的寿命预估。

在变换域中实现的SVD盲水印音频隐藏算法

数字水印在多媒体数据的版权保护方面引起了广泛关注。因此,提出了一种基于奇异值分析(Singular Value Decomposition,SVD)和指数-对数运算(Exponential Operation-Logarithm Operation,EO-LO)的变换域盲水印音频隐藏方案。首先对载体音频进行分帧,其中EO应用于每个帧。其次,对每帧执行离散余弦变换(Discrete Cosine Transform,DCT)得到具有能量集中特性的DCT系数后,继续执行离散小波变换(Discrete Wavelet Transformation,DWT),并获取其中的细节系数部分,并将水印信息通过量化函数嵌入到细节系数的最大奇异值中。最后,利用LO恢复出加密后的音频。仿真结果表明,所提的水印方案对不同攻击具有良好的鲁棒性,还具有较好的透明性和较高的嵌入容量。此外,与一些相关水印方案相比,它在透明性、鲁棒性和嵌入容量方面都具有较好的性能。

基于改进的灰色模型烟草产品销量的预测分析

针对非平滑序列短期预测精确度不高的问题,文章采用指数函数-对数函数变换法对数据列进行灰色预测分析,并从理论上证明此法对获取精准预测结果的优越性。最后,借助池州市烟草公司2007年1月——2012年1月黄山(金皖烟)硬盒同期数据,对其下一年同期销售量进行预测分析并与传统灰色预测模型相比较,进一步验证改进的灰色模型的有效性及优越性。

在变换域中实现的能量自适应音频隐藏算法

针对音频水印算法在隐藏信息时鲁棒性差的问题,提出了一种基于小波包分解(Wavelet Packet Decomposition,WPD)和指数-对数运算(Exponential Operation-Logarithm Operation,EO-LO)的变换域盲水印音频隐藏算法。该算法先将载体音频进行分帧处理并选取能量最高的L个音频帧;再对选中的帧进行小波包分解,将EO应用于选中的小波包子带系数;然后通过自适应改变小波包子带前后两部分的能量状态来嵌入信息;最后利用LO恢复出载密音频。由仿真结果可知,所提出的算法具有良好的鲁棒性和较好的透明性,与一些相关算法相比,它在鲁棒性方面具有较好的性能。

Is It Profitable to Invest According to the VIX Fear Index？

This study demonstrates how the volatility index （VIX） can help predict the returns for sequential trading days. Using a logit function and previous VIX information, we present an initial attempt to estimate the probability of a positive market return. The estimation procedure is applied to recent data on the S＆P500 and to the 10-year U.S. Treasury Bonds yields. Our findings indicate that such a relationship does exist and is significant, especially for the bond market. We also ran an investment simulation using different VIX scores and found that from 2004 to June 2009, VIX=18 was the score that yielded the highest.

A Study on Quantitative Evaluation of Calligraphy Characters

In this study, a numerical method was proposed to evaluate the calligraphy work called calligraphy evaluation system. Four classical chirographies of ＂Kaisho＂, ＂Gyosho＂, ＂Sousho＂ and ＂Hiragana＂, and 47 characters for each chirography, were selected and analyzed by this system. The ＂Sumi＂ distribution of character was clarified from 12 directions and summarized into four parts of horizontal part, diagonal left part, vertical part and diagonal fight part. The character＇s contour line was converted to a signal data in order to calculate roundness index. The degree of character＇s radian was presented by roundness index. The smooth index was calculated at the same time. Additionally, width index, ＂Sumi＂ ratio, stability index also were calculated to contrast the features of each style. The main character points of four styles of ＂Kaisho＇, ＂Gyosho＂, ＂Sousho＂, ＂Hiragana＂ were extracted to compare each other, and provide a reference for learners. The learners could obtain the quantitative data to understand their work＇s characteristics. It can also be compared with other person＇s work by this system in order to improve learners＇ writing skill.

Convergence Rate of the Asymmetric Deffuant-Weisbuch Dynamics

This paper considers the convergence rate of an asymmetric Deffuant-Weisbuch model.The model is composed by finite n interacting agents.In this model,agent i’s opinion is updated at each time,by first selecting one randomly from n agents,and then combining the selected agent j’s opinion if the distance between j’s opinion and i’s opinion is not larger than the confidence radiusε0.This yields the endogenously changing inter-agent topologies.Based on the previous result that all agents opinions will converge almost surely for any initial states,the authors prove that the expected potential function of the convergence rate is upper bounded by a negative exponential function of time t when opinions reach consensus finally and is upper bounded by a negative power function of time t when opinions converge to several different limits.

MASLOV-TYPE INDEX THEORY FOR SYMPLECTIC PATHS AND SPECTRAL FLOW (Ⅰ)

The spectral flow for paths of admissible operators in arbitrary Banach space is defined, and some properties of the spectral flow is studied.

Minimum contrast estimator for fractional Ornstein-Uhlenbeck processes

This paper proposes a minimum contrast methodology to estimate the drift parameter for the Ornstein-Uhlenbeck process driven by fractional Brownian motion of Hurst index, which is greater than one half. Both the strong consistency and the asymptotic normality of this minimum contrast estimator are studied based on the Laplace transform. The numerical simulation results confirm the theoretical analysis and show that the minimum contrast technique is effective and efficient.

Greenness Index from Phenocams Performs Well in Linking Climatic Factors and Monitoring Grass Phenology in a Temperate Prairie Ecosystem

Near-surface remote sensing(e.g.,digital cameras)has played an important role in capturing plant phenological metrics at either a focal or landscape scale.Exploring the relationship of the digital image-based greenness index(e.g.,Gcc,green chromatic coordinate)with that derived from satellites is critical for land surface process research.Moreover,our understanding of how well Gcc time series associate with environmental variables at field stations in North American prairies remains limited.This paper investigated the response of grass Gcc to daily environmental factors in 2018,such as soil moisture(temperature),air temperature,and solar radiation.Thereafter,using a derivative-based phenology extraction method,we evaluated the correspondence between key phenological events(mainly including start,end and length of growing season,and date with maximum greenness value)derived from Gcc,MODIS and VIIRS NDVI(EVI)for the period 2015–2018.The results showed that daily Gcc was in good agreement with ground-level environmental variables.Additionally,multivariate regression analysis identified that the grass growth in the study area was mainly affected by soil temperature and solar radiation,but not by air temperature.High frequency Gcc time series can respond immediately to precipitation events.In the same year,the phenological metrics retrieved from digital cameras and multiple satellites are similar,with spring phenology having a larger relative difference.There are distinct divergences between changing rates in the greenup and senescence stages.Gcc also shows a close relationship with growing degree days(GDD)derived from air temperature.This study evaluated the performance of a digital camera for monitoring vegetation phenological metrics and related climatic factors.This research will enable multiscale modeling of plant phenology and grassland resource management of temperate prairie ecosystems.

Relativistic beaming effect for blazars

In this paper, we revisit the relationship between the spectral index and the core-dominance parameter using a larger sample of 157 blazars (23 BL Lacertae objects and 134 flat spectrum radio quasars), compiled from the available literature. From the relevant data, we find the spectral index associated with the core-dominance parameter, for which a relativistic beaming effect is responsible. In addition, we make a comparison of the properties between BL Lacertae objects and flat spectrum radio quasars.

Radio spectral index of BL Lac objects

In this paper, the preliminary data from University of Michigan Radio Astronomy Observatory database （UMRAO） are used to discuss the radio spectral index properties of 8 BL Lacs. To do so, we calculated the radio spectral index, a （F oc va）, which was obtained by fitting the averaged flux densities in the bands （4.8 GHZ, 8 GHz, and 14.5 GHz） by binning the original for 7 d. We also calculated the time delay between the averaged lightcurves and the spectral variance. Our calculations and analysis give the following results. 1） The averaged logarithmic flux density at 8 GHz （logF） and the corresponding spectral index （or） have strong correlation for all the BL Lacs; 2） the lightcurves and the spectral variability have the similar profile for all the BL Lacs; 3） the lightcurves delay spectral variability for all sources but PKS 0735＋178, with the delay time ranging from 31 d to 125 d.

An exponential for the solutions model of collocation method of the HIV infection CD4＋T cells

In this paper, an exponential method is presented for the approximate solutions of the HIV infection model of CD4＋T. The method is based on exponential polynomi- als and collocation points. This model problem corresponds to a system of nonlinear ordinary differential equations. Matrix relations are constructed for the exponential functions. By aid of these matrix relations and the collocation points, the proposed technique transforms the model problem into a system of nonlinear algebraic equations. By solving the system of the algebraic equations, the unknown coefficients are com- puted and thus the approximate solutions are obtained. The applications of the method for the considered problem are given and the comparisons are made with the other methods.