科学文献随机性水平评价体系研究

系统分析了科学文献的形式与级别,根据科学文献的特点,选择了评价指标和等级标准.分别从文稿的社会效益因素和学术水平因素这一内容指标以及编校质量因素和刊发载体因素这一形式指标对科学文献进行计量评价,选择了社会效益及影响、理论贡献及科学意义、作者基本素质、人力资源、刊物影响、软硬件环境等宏观指标以及影响因子、数据库来源期刊、基金论文比例等微观指标进行科学评价.建立了由主要评价方面、评价要素、主要观测点组成的科学文献随机性水平评价体系.     

基于一种特定混沌映射的跳频系统

提出用一种简单的分段线性映射 ,构造混沌跳频序列 ,以取代跳频通信中的伪随机序列 (PN序列 )。分析了此混沌序列的相关特性 ,并与Logistic混沌序列进行了比较。仿真和实验结果表明 ,此序列具有较理想的相关特性 ,应用于跳频通信中可获得较好的抗干扰能力。     

Empirical data sets are algorithmically compressible: reply to McAllister?

James McAllister’s 2003 article, ‘Algorithmic randomness in empirical data’, claims that empirical data sets are algorithmically random, and hence incompressible. We show that this claim is mistaken. We present theoretical arguments and empirical evidence for compressibility, and discuss the matter in the framework of Minimum Message Length (MML) inference.     

模糊响应面法及其在边坡稳定可靠度分析中的应用

基于模糊随机变量理论,提出了边坡稳定的模糊响应面法.模糊响应面法将截集法与随机响应面法有机地组合在一起,可同时考虑边坡工程中存在的模糊性与随机性,是随机响应面法的推广.模糊响应面法可将隐式的模糊极限状态函数显式化,因而可以直观地显示基于模糊随机变量理论的模糊随机可靠度分析方法的实质.算例分析表明:可以将参数的不确定性用变异系数及模糊程度参数来表示,变异系数主要影响模糊可靠指标的大小,变异系数越大,可靠指标越小;模糊程度系数主要影响模糊可靠指标的模糊程度,模糊程度系数越大,可靠指标的模糊分布范围越宽.     

Foundations of quantum gravity: The role of principles grounded in empirical reality

When attempting to assess the strengths and weaknesses of various principles in their potential role of guiding the formulation of a theory of quantum gravity, it is crucial to distinguish between principles which are strongly supported by empirical data – either directly or indirectly – and principles which instead (merely) rely heavily on theoretical arguments for their justification. Principles in the latter category are not necessarily invalid, but their a priori foundational significance should be regarded with due caution. These remarks are illustrated in terms of the current standard models of cosmology and particle physics, as well as their respective underlying theories, i.e., essentially general relativity and quantum (field) theory. For instance, it is clear that both standard models are severely constrained by symmetry principles: an effective homogeneity and isotropy of the known universe on the largest scales in the case of cosmology and an underlying exact gauge symmetry of nuclear and electromagnetic interactions in the case of particle physics. However, in sharp contrast to the cosmological situation, where the relevant symmetry structure is more or less established directly on observational grounds, all known, nontrivial arguments for the “gauge principle” are purely theoretical (and far less conclusive than usually advocated). Similar remarks apply to the larger theoretical structures represented by general relativity and quantum (field) theory, where – actual or potential – empirical principles, such as the (Einstein) equivalence principle or EPR-type nonlocality, should be clearly differentiated from theoretical ones, such as general covariance or renormalizability. It is argued that if history is to be of any guidance, the best chance to obtain the key structural features of a putative quantum gravity theory is by deducing them, in some form, from the appropriate empirical principles (analogous to the manner in which, say, the idea that gravitation is a curved spacetime phenomenon is arguably implied by the equivalence principle). Theoretical principles may still be useful however in formulating a concrete theory (analogous to the manner in which, say, a suitable form of general covariance can still act as a sieve for separating theories of gravity from one another). It is subsequently argued that the appropriate empirical principles for deducing the key structural features of quantum gravity should at least include (i) quantum nonlocality, (ii) irreducible indeterminacy (or, essentially equivalently, given (i), relativistic causality), (iii) the thermodynamic arrow of time, (iv) homogeneity and isotropy of the observable universe on the largest scales. In each case, it is explained – when appropriate – how the principle in question could be implemented mathematically in a theory of quantum gravity, why it is considered to be of fundamental significance and also why contemporary accounts of it are insufficient. For instance, the high degree of uniformity observed in the Cosmic Microwave Background is usually regarded as theoretically problematic because of the existence of particle horizons, whereas the currently popular attempts to resolve this situation in terms of inflationary models are, for a number of reasons, less than satisfactory. However, rather than trying to account for the required empirical features dynamically, an arguably much more fruitful approach consists in attempting to account for these features directly, in the form of a lawlike initial condition within a theory of quantum gravity.     

时间序列确定性的指标检验方法

对于时间序列的生成机理是否服从于确定规律性的判断将直接影响到对其进行研究的理论框架的选择。提出了一种时间序列确定性成分的指标检验方法。该方法首先将待检验的时间序列重构于高维相空间中,寻找其主要几何特征在低维欧式空间中的投影,再将投影反射回高维相空间。通过比较原高维相空间与反射空间之间的偏差,来判断该序列的确定性。仿真实验证明了该方法具有可靠性。     

考虑飞机轮挡事件相关时间的航班时刻优化

针对航班延误问题,提出了从飞机轮挡事件的相关时间具有随机性的角度进行优化,建立了减少航班上轮挡及撤轮挡延误时间的概率约束型模型,并首次使用泰尔指数作为公平性目标函数。根据减少航班上轮挡延误、撤轮挡延误以及双延误的三种要求,可对建立的模型进行层次划分,从而达到不同的优化效果。以杭州萧山国际机场为算例进行算例验证,运用改进的粒子群算法进行求解,最终结果表明该模型对高峰期内的延误时间最高可减少26.4%,优化效果显著。     

编辑出版计算机化的形成机理探讨

本文试从编辑学科的理论框架的形成和发展趋势、当代编辑工作的性质和任务以及人类思维的发展追求精确化、科学化等角度,多方位地探讨了编辑出版计算机化的形成机理.     

岩溶坝区渗透系数的确定方法探讨

在岩溶地区，基于少量试验，要求岩体、特别是大范围内岩体的渗透系数是困难的。坝区许多地段的参数是未知的，需根据区内实测值参数对未知参数地段进行合理估计，并对估值的准确性进行评价，并对目前确定渗透系数的各种方法进行了阐述，重点分析了岩溶坝区渗透性的特点，对岩溶坝区渗透性的空间变异性和渗透系数的随机性进行了描述，提出了建立渗透系数随机模型的思路。     

自然树木风吹效果的分形模拟

为了使生成的植物图像更加形象逼真,文章给出了在分形的递归过程中,调用随机函数来模拟自然界中树木的方法和用Turbo C编写源程序。并能通过改变每根树枝负重的大小来偏离原方向一角度(负重越大,偏角越小)来实现树木的风吹效果。论文中还将随机性引入L系统,并给出了生成随机数的算法。