一种改进的LLL模糊度规约算法

整周模糊度的高效解算是GNSS高精度数据处理中的关键,基于格论进行GNSS模糊度估计时需要通过格基规约来实现最优整周模糊度向量的快速搜索。针对高维情况下常规LLL规约算法辅助整周模糊度解算存在规约耗时较长和规约性能有限的问题,引入最小列旋转QR分解技术对基向量进行预排序,采用延后尺度规约和部分尺度规约来减少规约过程中的冗余尺度规约,以改善LLL算法的执行效果。分别通过模拟和实测数据进行实验,结果表明:改进后的LLL算法可以明显降低格基规约耗时,实测环境下其规约效率相比于传统方法提高了约10倍,且能够保证较好的规约性能,从而有效提升高维模糊度的解算效率。     

A defense of indeterminism

My goal is to defend the indeterminist approach to vagueness, according to which a borderline vague utterance is neither true nor false. Indeterminism appears to contradict bivalence and the disquotational schema for truth. I agree that indeterminism compels us to modify each of these principles. Kit Fine has defended indeterminism by claiming that ordinary ambiguous sentences are neither true nor false when one disambiguation is true and the other is false. But even if Fine is right about sentences, his point does not seem to generalize to utterances. What the indeterminist needs -- and what ordinary ambiguity does not provide -- is an ambiguous utterance where what is being said is indeterminate between two different propositions. I will show that such cases exist. These cases imply that the modifications that indeterminism makes to bivalence and the disquotational schema are required independently of indeterminism, in fact independently of vagueness.     

GPS载波相位双差整周模糊度在航求解

鉴于整周模糊度的快速解算是GPS载波相位测姿的一个主要技术难题,从系统实时性、动态性要求出发,给出了一个整周模糊度的快速解算的新方法。其主要特点为:利用三角函数约束条件减少模糊度搜索范围,优选指标不受基线运动状态影响,可利用多历元动态基线数据进行平差。实验结果验证了该算法的有效性。     

A review of recent methods for the determination of ranges of feasible solutions resulting from soft modelling analyses of multivariate data

Soft modelling or multivariate curve resolution (MCR) are well-known methodologies for the analysis of multivariate data in many different application fields. Results obtained by soft modelling methods are very likely impaired by rotational and scaling ambiguities, i.e. a full range of feasible solutions can describe the data equally well while fulfilling the constraints of the system. These issues are severely limiting the applicability of these methods and therefore, they can be considered as the most challenging ones. The purpose of the current review is to describe and critically compare the available methods that attempt at determining the range of ambiguity for the case of 3-component systems. Theoretical and practical aspects are discussed, based on a collection of simulated examples containing noise-free and noisy data sets as well as an experimental example.     

Heisenberg's Inequality and Logarithmic Heisenberg's Inequality for Ambiguity Function

In this article we discuss the relation between Heisenberg's inequality and logarithmic Heisenberg's (entropy) inequality for ambiguity function. After building up a Heisenberg's inequality, we obtain a connection of variance with entropy by variational method. Using classical Taylor's expansion, we prove that the equality in Heisenberg's inequality holds if and only if the entropy of 2k - 1 order is equal to (2k - 1}!.     

基于组合线阵的近程运动小目标被动定位跟踪

针对水下运动小目标被动探测与定位问题,提出了分段组合子阵联合处理探测方法,各探测子阵采用相互垂直结构布局,克服了单阵方位模糊及无法定位等问题。研究了分段组合子阵的宽带最小方差无畸变失真响应近场聚焦目标定位方法,实现了近程蛙人等水下小目标被动高精度定位。在此基础上,采用卡尔曼滤波算法对目标运动轨迹进行预测估计,将目标定位信息与跟踪轨迹信息进行匹配,实现高背景噪音下的运动小目标的跟踪处理。理论分析及仿真结果表明,分段子阵联合处理能有效对水下运动小目标进行定位和跟踪,海试试验进一步验证了该方法的有效性。     

Infinite class of new sign ambiguities

In 1934, two kinds of multiplicative relations, the norm and the Davenport-Hasse relations, between Gauss sums, were known. In 1964, H. Hasse conjectured that the norm and the Davenport-Hasse relations were the only multiplicative relations connecting Gauss sums over Fp. However, in 1966, K. Yamamoto provided a simple counterexample disproving the conjecture. This counterexample was a new type of multiplicative relation, called a sign ambiguity, involving a ± sign not connected to elementary properties of Gauss sums. In this paper, we give an explicit product formula involving Gauss sums which generates an infinite class of new sign ambiguities, and we resolve the ambiguous sign by using Stickelberger?s theorem.     

交叉熵——计算语言学消歧的一种工具

歧义问题的描述和消除问题是制约计算语言学发展的瓶颈问题.将交叉熵引入计算语言学消岐领域.采用语句的真实语义作为交叉熵的训练集的先验信息,将机器翻译的语义作为测试集后验信息,计算两者的交叉熵,并以交叉熵指导对歧义的辨识和消除.实例表明,该方法简洁有效,易于计算机自适应实现,交叉熵不失为计算语言学消岐的一种较为有效的工具.     

A practical inventory control policy using operational statistics

Consider the newsvendor inventory control problem with an ambiguous demand. The traditional approach of separating the parameter estimation and the maximization of the expected profit leads to a suboptimal inventory policy. Operational statistics, introduced in this paper, provides a better solution by integrating the estimation and the optimization tasks.     

一种消除测速模糊的梳状谱信号设计方法

相比于传统信号,梳状谱具有更好的混响抑制能力,但其容易产生多普勒测速模糊。为了解决这一问题,设计了一种新的几何梳状谱信号,通过分析测速模糊产生的原因,在传统频点计算方法的基础上,利用在信号频点计算中加入一组抗多普勒频率间隔的方法,以降低频点的重合。仿真分析证明,提出的梳状谱信号设计方法有效的减少了速度搜索时频谱重叠的程度,无论在噪声还是混响限制条件下均可以获得一个明显的输出峰值,避免了测速模糊的问题,可以获得比传统信号更好的检测性能。