A novel adaptive cooperative location algorithm for wireless sensor networks

To overcome the disadvantages of the location algorithm based on received signal strength indication(RSSI) in the existing wireless sensor networks(WSNs),a novel adaptive cooperative location algorithm is proposed.To tolerate some minor errors in the information of node position,a reference anchor node is employed.On the other hand,Dixon method is used to remove the outliers of RSSI,the standard deviation threshold of RSSI and the learning model are put forward to reduce the ranging error of RSSI and improve the positioning precision effectively.Simulations are run to evaluate the performance of the algorithm.The results show that the proposed algorithm offers more precise location and better stability and robustness.     

铌酸锂声光偏转器宽带匹配模式研究

通过求解铌酸锂晶体反常声光衍射的Dixon方程,给出了不同入射光情况下超声波方向和衍射光方向关于超声频率变化的关系曲线,确定了铌酸锂反常声光偏转器宽带设计方法,通过理论计算得到了宽带工作模式的具体设计参数.计算结果表明,选择合适的入射光方向和超声主方向可以有效扩大声光偏转器的布拉格带宽.     

Comparing acceleration techniques for the Dixon and Macaulay resultants

The Bezout–Dixon resultant method for solving systems of polynomial equations lends itself to various heuristic acceleration techniques, previously reported by the present author, which can be extraordinarily effective. In this paper we will discuss how well these techniques apply to the Macaulay resultant. In brief, we find that they do work there with some difficulties, but the Dixon method is greatly superior.     

基于Dixon结式的一种九杆巴氏桁架位移分析

将Dixon结式运用到平面基本运动链的位移分析中,完成了一种两耦合度九杆巴氏桁架的位移分析。结合矢量法和复数法建立4个几何约束方程式,使用Dixon结式构造22×22的Dixon矩阵,提取公因式后将矩阵的行列式展开得到一元六十次多项式方程,回代过程中去掉4组增根得到56组解。为了对结果进行验证,同时使用同伦连续法对一个数字算例进行计算,两种方法得到的结果一致,说明这种巴氏桁架的装配构型数目最大值是56。     

空间6R机器人位置反解的对偶四元数法

将对偶四元数的复指数形式引入到串联机械手位置逆解分析中,提出一种空间6R串联机械手位置逆解的新算法。采用复指数形式的四元数以及对偶四元数建立空间6R串联机械手位置逆解的封闭方程。通过对获得的四个位置约束方程构造Dixon结式,得到一个6×6的行列式等于零的矩阵,去掉其中相关的公因式,导出既无增根也无漏根的一元16次方程。通过实际计算,得出该机器人位置反解一元高次方程的次数为16且最多只有16组解的结论。通过一种串联机械手逆运动学分析为例进行求解验证,数字实例证明了该方法既无增根也无漏根。这种方法可达到在消元过程中自动消除机构结构参数变化或者轨迹规划过程中某些奇异位置造成的方程相关性,避免增根的产生。     

Site/Non-Site: Extending the Parameters in Contemporary Landscape

As the world teeters on the verge of environmental collapse, landscape architecture has taken on a new significance offering a longed-for sanctuary for our increasingly urbanised lives. Here, in his introduction to the issue, guest-editor Michael Spens explains how by taking its impetus from land art, landscape architecture, as an expanded field, transcends the conventional confines of site. This renders it possible to read architecture ‘as landscape, or as non-landscape, as building becomes non-site’ and the ‘site indeed materialises as the work per se’. Copyright © 2007 John Wiley & Sons, Ltd.     

Complexity of constructing Dixon resultant matrix

Dixon resultant is a fundamental tool of elimination theory in the study and practice of algebraic geometry. It has provided the efficient and practical solutions to some benchmark problems in a variety of application domains, such as automated reasoning, automatic control, and solid modelling. The major task of solutions is to construct the Dixon resultant matrix, the entries of which are more complicated than the entries of other resultant matrices. An existing extended recurrence formula can construct the Dixon resultant matrix fast. In this paper, we present a detailed analysis of the computational complexity of the recurrence formula for the general multivariate setting. Parallel computation can be applied to speed up the recursive procedure. Furthermore, we also generalize the computational complexity of three bivariate polynomials to the general multivariate case by using the construction of standard Dixon resultant matrix. Some experimental results are demonstrated by a range of nontrivial examples.     

基于结式消元法的多曲面拼接

介绍Sylvester和Dixon两种结式消元方法,分别讨论图形顺接和首尾串接的情况下,用不同结式方法来求三个曲面拼接方程。通过对比分析,可以知道在三个曲面拼接情形下,运用Sylvester结式思路较简单,易实现,应用更广泛。     

It's All About Getting What You Want What We Want Is to Make Work That Fits

Today we live in a culture of institutionalised public realm – it is not the grass-roots activity of the 1970s. However, Liza Fior, Katherine Clarke and Sophie Handler of muf architecture explain how the collaborative nature of the practice, both internally and in its approach to any project brief, defines how, today, a community is as strong as the questions it is prepared to ask of itself. Copyright © 2005 John Wiley & Sons, Ltd.     

浅谈狄克逊准则的速记方法及运用

在检定检测工作中使用仪器仪表的测量结果作为参考,但是由于仪器仪表本身的限制和人员操作、环境因素等的影响,测量准确度只能在一定的区间范围内.在计量学中,为了保证测量结果的准确,往往取多次测量的平均值作为测量结果.但是重复测量中,由于众多因素影响,仪器仪表也可能给出并不符合预期目的离群值.如果我们把这些数据值和正常数据值放...