能量约束下的Bézier曲线构造

Bézier曲线是计算机辅助几何设计中应用广泛的曲线造型工具,构造具有能量约束的曲线也是曲线造型研究的重要内容之一.构造给定首末控制顶点与初始切方向的Bézier曲线,当其满足jerk能量极小时,其余控制顶点可以由已知条件与参数α确定;其中α与初始切向量长度有关.当曲线满足弯曲能量约束时,参数α唯一确定,从而对有序点集,可以显式地构造满足jerk能量极小与弯曲能量约束的G^1拼接组合Bézier曲线.最后,通过具体实例构造通过给定有序点集且满足能量约束的组合Bézier曲线,并与其他方法所得结果进行对比,验证了方法的有效性与可行性.     

Wind Turbine Efficiency Under Altitude Consideration Using an Improved Particle Swarm Framework

In this work, the concepts of particle swarm optimization-based method, named non-Gaussian improved particle swarm optimization for minimizing the cost of energy (COE) of wind turbines (WTs) on high-altitude sites are introduced. Since the COE depends on site specification constants and initialized parameters of wind turbine, the focus was on the design optimization of rotor radius, hub height and rated power. Based on literature, the COE is converted to the Saudi Arabia context. Thus, the constrained wind turbine optimization problem is developed. Then, non-Gaussian improved particle swarm optimization is provided and compared with the conventional particle swarm optimization for solving the optimization design in wind turbine efficiency under different altitudes ranging from 2500 to 4000 m. The results show that as altitude rises, the optimal rotor radius grows, but the optimal hub height and rated power drop, resulting in an increase in COE. Further, the non-Gaussian method display a faster convergence compared to the classical particle swarm optimization. These findings will be useful as a reference for wind turbine design at high altitudes. Thus, it could be employed to optimize the initialized parameter of wind turbine for the planned and largest wind farm in Saudi Arabia in Dumat Al-Jandal selected site.

     

张量积Bézier曲面降多阶逼近

给出了一种基于最小二乘范数下的Bézier曲面降多阶逼近误差的矩阵计算公式。根据带角点高阶插值条件下原张量积Bézier曲面与降多阶张量积Bézier曲面的误差函数在[0,1]x[0,1]上取极小值,得到降多阶张量积Bézier曲面的控制顶点的矩阵表达式。通过数值例子显示采用该方法所得的降多阶曲面对原曲面有较好的逼近效果。将Bézier曲线降阶逼近的迭代方法推广到曲面,得到曲面降阶逼近的迭代方法,并给出了相应的数值实例。     

Geometrical Moir Methodand Its Application

A geometrical moir method for displaying directly isochromatics and isoclinics of a diametrically pressed circular disk is presented. It is demonstrated that by using two identical or different Wulff nets (or grids) not only the stress fields of a circular disk can be displayed, but the u -and v -displacement fields can also be produced.     

Reversible Data Hiding for Medical Images in Cloud Computing Environments Based on Chaotic Hénon Map

Reversible data hiding techniques are capable of reconstructing the original cover image from stego-images. Recently, many researchers have focused on reversible data hiding to protect intellectual property rights. In this paper, we combine reversible data hiding with the chaotic Hénon map as an encryption technique to achieve an acceptable level of confidentiality in cloud computing environments. And, Haar digital wavelet transformation (HDWT) is also applied to convert an image from a spatial domain into a frequency domain. And then the decimal of coefficients and integer of high frequency band are modified for hiding secret bits. Finally, the modified coefficients are inversely transformed to stego-images.     

Mapping the contours of contemporary positive psychology.

This paper seeks to quantify scholarly interest in the rapidly emerging field of Positive Psychology (PP) and to empirically map the contours of the discipline using six different methodologies. Results document extraordinary growth in the last decade and confirm that scholars in this area have devoted the lion's share of their attention to two of the three 'Pillars' of PP as proposed by Seligman and Csikszentmihalyi (2000): (1) the study of positive subjective experience and (2) positive personal traits. While interest in positive institutions has been somewhat sparse, there has been increased concern with the topics of 'resilience' and eudaimonia (broadly defined). The latter developments help to dispel the myth that PP is an elite endeavour solely concerned with Pollyanna-style 'happiology' in people who find themselves in idyllic circumstances. Hopefully the results of our content analysis of the field will encourage instructors who teach PP to provide their students with a well-balanced curriculum, one that accurately reflects the heterogeneity of the field, and one that mirrors recent scholarly trends. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Magnéli相亚氧化钛的制备及其应用

Magnéli相亚氧化钛材料是一类分子式为TinO2n-1(3＜n＜10)的导电化合物,该类化合物是于20世纪50年代通过XRD技术发现.对这些钛氧化物的制备及其物化性质进行介绍；着重介绍它们在铅蓄电池、液流电池和燃料电池等化学电源电极材料方面的应用进展.     

Repetition and the SNARC effect with one- and two-digit numbers.

The SNARC (Spatial Numerical Association of Response Codes) effect is the finding that small numbers elicit faster left than right responses and large numbers elicit faster right than left responses. This effect suggests that numbers activate left-right magnitude-laterality codes and that these codes interact with the selection of left-right responses. In the present research, subjects made parity decisions for one-digit numbers (in Experiment 1) and two-digit numbers (in Experiment 2), and we examined the effect of stimulus repetition on the SNARC effect. With single-digit stimuli, responses were faster and the SNARC effect was eliminated when stimuli were identical on successive trials. With two-digit stimuli, responses were faster when the ones digit was repeated, but the SNARC effect was found regardless of whether the digit was repeated or not. We argue that magnitude-laterality codes are activated in the process of accessing number information in memory and that this process can be short circuited if the visual stimulus matches that on the previous trial. Thus, no SNARC effect is found in Experiment 1 when identical stimuli are presented on successive trials. However, this result is not found in Experiment 2 because successive stimuli do not match even if the ones digit is repeated. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

共焦法布里-珀罗干涉显微测头光学特性分析

根据纳米计量分辨力的要求,设计一套共焦法布里-珀罗(F-P)干涉显微测头。系统光源采用保偏光纤直接导入,从F-P腔外入射。光路设计成便于减小光学共模噪音的差动形式。通过建立模型分析系统光学特性,得出反射平板的最佳反射率以及共焦结构对干涉条纹的影响。实验验证表明反射平板反射率为40%时可以使系统得到对比度高,信噪比好的干涉条纹;针孔光阑可以方便寻找测量透镜的焦点和减小杂散光的噪音;系统轴向分辨力达到0.2nm。     

校正源方位存在偏差时的幅相误差顽健校正算法

针对校正源方位偏差会影响幅相误差校正精度这一问题,在假设校正源方位偏差的概率分布已知的条件下,依据子空间拟合准则和Bayesian估计理论框架,给出了一种抑制校正源方位偏差的幅相误差顽健校正算法。该算法可在无需估计校正源方位的情况下,通过计算某实对称矩阵最小特征值对应的特征向量获得幅相误差的顽健估计。推导了参数估计的CRB(Cramer-Rao bound),分析了顽健算法的渐近性能以及Cheng方法在校正源方位有偏差时的渐近性能。理论分析和仿真实验均表明:在一定条件下,所提出的算法的渐近性能可达到CRB,并且优于Cheng方法的渐近性能(当校正源方位有偏差时)。