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251.
词语权重计算是自然语言处理中的重要问题,是文档语义表示的重要实现手段.词语的权重主要由两部分决定,一部分是词语在文档中的重要性度量,另一部分是基于统计方法所得的词语在区分不同文档能力上的度量即词语全局权重.本文就针对有相对稳定性的词语全局权重计算方法分析比较了现有的几种词语全局权重计算方法,并在此基础上提出了一种新的组合词语全局权重计算方法,实验证明本文提出的新方法能够有效地提高了系统的性能. 相似文献
252.
钟义信 《北京邮电大学学报》1991,14(3):1
迄今,人们所熟悉的信息理论是 C.E.Shannon 在1948年建立的概率统计型的信息理论,即 Shannon 信息论.本文试图提出一种新的信息理论,即全信息理论,以适应新的发展的需要.文中将阐明全信息理论产生的背景、全信息的基本概念、全信息的度量方法、以及全信息理论应用的前景. 相似文献
253.
为解决在粉煤灰掺入混凝土及砂浆时其早期强度偏低的问题,采用了掺化学外加剂的方法,以激发粉煤灰的潜在活性,达到解决早期强度偏低的缺陷。掺入早强磨细粉煤灰25%~30%取代同等量水泥,不仅降低工程造价,而且为利用工业废渣开辟了新的途径。 相似文献
254.
255.
An analysis of technology potential of a metal-based high temperature latent heat storage for the application of process steam backup for industrial parks in Germany was carried out. To investigate the integration of the storage into a process steam network, dynamic process simulations were performed. Furthermore, the analysis includes ecological and economical calculations for various fuel types of industrial power plants, plant sizes and auxiliary fuels. Basis of all calculations is an extensive research conducted on the industrial parks in Germany with a dedicated power plant and process steam utilization. 相似文献
256.
Supporting exact indexing of arbitrarily rotated shapes and periodic time series under Euclidean and warping distance measures 总被引:1,自引:0,他引:1
Eamonn Keogh Li Wei Xiaopeng Xi Michail Vlachos Sang-Hee Lee Pavlos Protopapas 《The VLDB Journal The International Journal on Very Large Data Bases》2009,18(3):611-630
Shape matching and indexing is important topic in its own right, and is a fundamental subroutine in most shape data mining
algorithms. Given the ubiquity of shape, shape matching is an important problem with applications in domains as diverse as
biometrics, industry, medicine, zoology and anthropology. The distance/similarity measure for used for shape matching must
be invariant to many distortions, including scale, offset, noise, articulation, partial occlusion, etc. Most of these distortions
are relatively easy to handle, either in the representation of the data or in the similarity measure used. However, rotation
invariance is noted in the literature as being an especially difficult challenge. Current approaches typically try to achieve
rotation invariance in the representation of the data, at the expense of discrimination ability, or in the distance measure,
at the expense of efficiency. In this work, we show that we can take the slow but accurate approaches and dramatically speed
them up. On real world problems our technique can take current approaches and make them four orders of magnitude faster without
false dismissals. Moreover, our technique can be used with any of the dozens of existing shape representations and with all
the most popular distance measures including Euclidean distance, dynamic time warping and Longest Common Subsequence. We further
show that our indexing technique can be used to index star light curves, an important type of astronomical data, without modification.
Reproducible Research Statement: All datasets and images used in this work are freely available at . 相似文献
257.
Expertise-based peer selection in Peer-to-Peer networks 总被引:1,自引:0,他引:1
258.
At EuroCrypt '99 Paillier proposed a new encryption scheme based on higher residuosity classes. The new scheme was proven
to be one-way under the assumption that computing
N -residuosity classes in Z
N2
*
is hard. Similarly the scheme can be proven to be semantically secure under a much stronger decisional assumption: given w ∈ Z
N2
*
it is impossible to decide if w is an N -residue or not.
In this paper we examine the bit security of Paillier's scheme. We prove that if computing residuosity classes is hard, then
given a random w it is impossible to predict the least significant bit of its class significantly better than at random. This immediately
yields a way to obtain semantic security without relying on the decisional assumption (at the cost of several invocations
of Paillier's original function).
In order to improve efficiency we then turn to the problem of simultaneous security of many bits. We prove that Paillier's
scheme hides n-b (up to O(n) ) bits if one assumes that computing the class c of a random w remains hard even when we are told that c<2
b
. We thoroughly examine the security of this stronger version of the intractability of the class problem.
An important theoretical implication of our result is the construction of the first trapdoor function that hides super-logarithmically
(up to O(n) ) many bits. We generalize our techniques to provide sufficient conditions for a trapdoor function to have this property. 相似文献
259.
B. Shekar M. Narasimha Murty G. Krishna 《Journal of Intelligent and Robotic Systems》1989,2(4):361-379
The notion of concept based on the semantics of objects is defined and illustrated. An underlying thread connecting a subset of concepts is identified. This class of concepts, called the Conceptual Transformer is defined and illustrated with real-world examples. This class finds a natural application in any area where objects can be characterized by functionality. Some interesting application areas are knowledge classification, manufacturing automation, and pattern synthesis. The salient features of this class are elaborated and a knowledge structure for representing concepts is proposed. The effect of these transformers on knowledge-directed classification, which results in the formation of virtual clusters, is examined in detail. We make use of examples from real life to bring out the efficacy of the proposed transformerbased, concept-directed classification. 相似文献
260.
可移植汉语人一机接口是我国界当前研究的热点之一。本文通过分析汉语的特点, 对在微机上建造中小型应用系统的可移植汉语人一机接口, 提出了一种切实可行的实现方法, 文中还介绍了反用这一方法实现的实验系统的具体结构。 相似文献