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141.
Global Optimization in Any Minkowski Metric: A Permutation-Translation Simulated Annealing Algorithm for Multidimensional Scaling 总被引:3,自引:1,他引:2
It is well known that considering a non-Euclidean Minkowski metric in Multidimensional Scaling, either for the distance model
or for the loss function, increases the computational problem of local minima considerably. In this paper, we propose an algorithm
in which both the loss function and the composition rule can be considered in any Minkowski metric, using a multivariate randomly
alternating Simulated Annealing procedure with permutation and translation phases. The algorithm has been implemented in Fortran
and tested over classical and simulated data matrices with sizes up to 200 objects. A study has been carried out with some
of the common loss functions to determine the most suitable values for the main parameters. The experimental results confirm
the theoretical expectation that Simulated Annealing is a suitable strategy to deal by itself with the optimization problems
in Multidimensional Scaling, in particular for City-Block, Euclidean and Infinity metrics. 相似文献
142.
LIU JianCai XU JiaKai NING XinBao TIAN Run 《科学通报(英文版)》2007,52(17):2438-2442
The characterization of non-stationary signal requires joint time and frequency information. However, time and frequency are a pair of non-commuting variables that cannot constitute a joint probability density in the time-frequency plane. The time-frequency distributions have difficult interpretation problems arising from negative and complex values or spurious components. In this paper, we get time-frequency information from the marginal distributions in rotated directions in the time-frequency plane. The rigorous probability interpretation of the marginal distributions is without any ambiguities. This time-frequency transformation is similar to the computerized axial tomography (CT or CAT) and is applied to signal analysis and signal detection and reveals a lot of advantages especially in the signal detection of the low signal/noise (S/N). 相似文献
143.
Alexandra Sauer 《Systemic Practice and Action Research》2008,21(6):497-515
The participation of non-state actors in implementation processes is often understood as a means to increase compliance efficiency.
But the implementation of spatial policies frequently focuses on pre-established goals, processes and instruments and thus
renders difficult open discourse and shared decision-making. This paper introduces conflict pattern analysis (CPA) as a tool
that supports the analysis of the actual actor constellation in order to define efficient approaches that avoid common problems
of participatory processes. CPA is a semi-formalised method that helps to identify key-actors, their relations and interaction
amongst each other as well as their core beliefs, interests and resources. It aggregates this information to interaction patterns
that can be compared, classified and linked to different participatory methods on a theoretically informed basis. Particularly
on the local and regional level, this could be the first step for successful (participatory) implementation strategies. 相似文献
144.
分析了工程技术档案管理工作的现状,从设计思路、软件开发等方面介绍了煤矿技术档案数据库系统。 相似文献
145.
S. K. MISHRA Shouyang WANG K. K. LAI 《系统科学与复杂性》2007,20(3):344-349
In this paper, we introduce a new class of generalized convex function, namely, a-pseudounivex function, by combining the concepts of pseudo-univex and α-invex functions. Further, we establish some relationships between vector variational-like inequality problems and vector optimization problems under the assumptions of α-pseudo-univex functions. Results obtained in this paper present a refinement and improvement of previously known results. 相似文献
146.
本文将一种非水溶性光致聚合物涂布在软片基底上,用匹配液将其固定在玻璃片上用来拍摄反射式全息图,衍射效率高,得到很好的图象效果,并对软片全息图的拍摄条件和保存条件进行了研究. 相似文献
147.
A theoretical model for mid-and low-latitude ionospheric electric fields in realistic geomagnetic fields 总被引:1,自引:1,他引:0
The geomagnetic fields, which play important roles in the ionospheric dynamo, can greatly affect the global distribution of ionospheric electric fields, currents and other ionospheric electrodynamics phenomena. In the study of ionospheric electrodynamics phenomena, such as the longitudinal variations of ionospheric electric fields, the non-dipolar component of the geomagnetic fields must be taken into account. In this paper, we deduce a theoretical electric field model for ionospheric dynamo at mid- and low-latitude which adopt a modified magnetic apex coordinates system. In the new electric field model, the geomagnetic fields can be calculated from either the IGRF model or the dipole field model, and the neutral winds and conductivities are calculated based on empirical models. Then the dynamo equation for the electric potential is finally solved in terms of the line-by-line iteration method, and the ionospheric electric fields and currents are derived from the calculated potential. Our model can reproduce the main features of the ionospheric electrodynamics processes, so it will be a useful tool for the investigation of the upper atmosphere and ionosphere. 相似文献
148.
针对空间点检测问题给出了一种简便而精确的空间点检测方法并建立了实验环境下的数学模型,提出了视差为零时,所测得的空间点深度最接近真实值的假设,并得到如下结论:给定空间点,深度不变,基线越短,光轴的夹角越小;深度改变时,基线一定,则深度越长,夹角越小。推导出在不同基线、不同深度下摄像机光轴之间理想夹角的数学模型并通过实验进行了验证。该方法对实际双目检测系统的摄像机配置有一定的指导作用。 相似文献
149.
对杨叶锈病在上海的发生状况、病原菌冬孢子、夏孢子的形态及其越冬后的萌发和侵染能力进行研究。研究中未发现病菌的转主寄主,且冬孢子作用不明;在病叶上越冬的夏孢子能够萌发,用越冬夏孢子接种杨树可以导致发病。初步研究表明杨叶锈病在上海无转主寄主,初侵染源为病叶上越冬的夏孢子堆。 相似文献
150.
研究了用水合硫酸铁替代硫酸作催化剂,催化丙烯酸与多种醇的酯化反应,发现其具有良好的催化活性.探讨了醇的结构对催化剂和酯化反应的影响,以及催化酯化反应的可能机理 相似文献