Schreiber approach for GPS carrier phase ambiguity resolution

Differenced GPS carrier phase observations are usually used in GPS positioning to eliminate the various common GPS errors. A different approach is proposed in this paper where no differencing of the observations is required. In this method, the common GPS errors are modelled explicitly and eliminated by introducing the Schreiber method, which is used in traditional geodesy to eliminate the azimuth unknowns in observation equations. The paper first introduces the Schreiber method, and then discusses its application to the various GPS common-mode error models. It is shown that if only the real ambiguity solution is concerned, the estimate of the position parameters from the Schreiber approach is the same as that from the differencing approach. However, the variance of the ambiguity estimate from the Schreiber approach is smaller than that from the differencing approach. Numerical examples are given to show that the results are reliable.     

二元精馏中最小回流比的计算

该文得出了二元精馏计算中进料状态参数为任意值时最小回流比Ｒ＿ｍ的计算方法。当ｑ＝０与１时，其计算结果与常规方法计算所得结果完全一致。     

ERROR ESTIMATION OF THE APPROXIMATION ALGORITHM FOR THE WINDY POSTMAN PROBLEM

If we restrict the postman to traversing each edge at most twice in the windypostman problem (WPP), we will get a new problem: 2WPP. An approximation algorithmhas been posed by M. Guan for the WPP. In the present paper, we improve the estimatederror given by M. Guan and show that we can estimate the error for the 2WPP by findinga minimum cost circulation. We also pose a new sufficient condition for the equivalencebetween WPP and 2WPP, which can be checked in polynomial time steps.     

最小汉明距离译码的原核生物DNA表达效率分析

鉴于通信系统结构,将分子生物的信息传递过程用通信模型描述,采用最小汉明距离译码算法,分析核糖体16S rRNA的突变对原核生物DNA翻译效率表达的影响,仿真结果表明原核生物以16S rRNA作为一个标准的差错校验码对DNA全序列进行纠错,证明了运用通信编码理论分析原核生物的遗传信息传递的可行性.     

准二维非恒定非均匀泥沙数学模型

在一雏非恒定非均匀泥沙数学模型研究的基础上,提出了可以模拟横向冲淤变形以及河宽变化的准二维非恒定非均匀泥沙数学模型．将横断面沿河道流向分成若干个流管,对每个流管利用非耦合法分别求解水流方程和泥沙方程．运用Preissmann四点偏心隐式格式对水流连续方程和运动方程进行离散,并用追赶法求解．采用迎风格式将悬移质连续方程离散成差分方程求解．根据最小能耗率原理,判别河床冲淤变化方向,以确定河宽是否变化、该模型弥补了以往大多数准二维泥沙数学模型只能按等流量划分流管,且只能模拟恒定流、均匀沙、固定河宽情况下的河床冲淤变化的缺陷．利用青铜峡水库实测的水沙资料,对所建立的模型进行了验证,计算结果与实测值吻合良好．     

基于节点雅可比矩阵确定弱节点排序的指标比较

针对只对系统中某些关键负荷节点进行弱节点排序的需要,提出了衡量节点雅可比矩阵奇异的若干指标,将这些指标应用于弱节点排序并对其有效性进行了评价．算例表明除行列式指标外其他各种指标均适合于弱节点排序,而节点灵敏度指标由于其鲜明的物理意义而被推荐用于弱节点排序．     

中巴资源卫星02B星土地覆盖分类

为了能够将中巴资源卫星02B星更好地用于民用事业,需要对其数据进行精确研究以达到适合民用的目的.针对中巴资源卫星02B星CCD图像数据用监督分类中的最大似然法和最小距离法进行土地覆盖分类比较.通过分类精度评价的结果进行说明监督分类有效的用于该星分类,其分类图可以用于城市、土地、林业等动态变化监测.     

A new algorithm for degree-constrained minimum spanning tree based on the reduction technique

The degree-constrained minimum spanning tree (DCMST) is an NP-hard problem in graph theory. It consists of finding a spanning tree whose vertices should not exceed some given maximum degrees and whose total edge length is minimal. In this paper, novel mathematical properties for DCMST are indicated which lead to a new reduction algorithm that can significantly reduce the size of the problem. Also an algorithm for DCMST to solve the smaller problem is presented which has been pre-processed by reduction algorithm.     

黄河流域土壤侵蚀快速评估

在前期研究的基础上,将基于最小图斑的土壤侵蚀快速评估方法应用到黄河流域土壤侵蚀的评估中,建立了土壤侵蚀特征指标(EI)与土壤侵蚀强度E之间的判别分析关系,并根据判别函数判断EI的归属类别,从而获得每个图斑的土壤侵蚀强度.经敏感性分析,说明评估结果是稳定可靠的.应用表明,土壤侵蚀特征指标能够较好地表征流域土壤侵蚀强度;土壤侵蚀快速评估方法在实际应用中具有明显优势,不仅对输入数据和参数要求相对较低,而且能够提高模型的评估效率.     

lp2∪T（1，1，n）的伴随等价图类

利用伴随多项式的最小实数根的性质完整刻画了lp2∪T（1,1,n）（n≥1）的伴随等价图类．