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1.
基于神经网络的网络验证码识别研究   总被引:2,自引:0,他引:2       下载免费PDF全文
本文首先介绍了神经网络的基本思想,提出了一种基于神经网络的网络验证码的识别方法,并利用开源的神经网络包JOONE用Java技术实现了验证码识别软件。最后通过训练样本对其进行了实验分析,取得了较高的识别率。  相似文献   

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Legacy software systems present a high level of entropy combined with imprecise documentation. This makes their maintenance more difficult, more time consuming, and costlier. In order to address these issues, many organizations have been migrating their legacy systems to emerging technologies. In this paper, we describe a computer-supported approach aimed at supporting the migration of procedural software systems to the object-oriented (OO) technology. Our approach is based on the automatic formation of concepts, and uses information extracted directly from code to identify objects. The approach tends, thus, to minimize the need for domain application experts.  相似文献   

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一种基于Hilbert排列码的GIS空间索引方法   总被引:9,自引:0,他引:9  
分析了基于栅格格网的索引数据结构在空间查询中的重要地位,讨论了基于多维数据一维映射的空间排列的优点,对Morton码、Gray码、Hibert码和Sierpinsky码的空间聚类特征进行了分析和比较,得出了Hilbert码在空间查询中效率最高的结论,考虑到基于特征的GIS数据模型的特点,兼顾内存索引与磁盘索引,提出了基于Hilbert空间排列的点特征二叉平衡排序树动态索引结构和基于角点回溯的线特征索引结构,并对其在GIS空间查询中的应用方法进行了论述。  相似文献   

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一种新型Turbo码交织器设计方法   总被引:4,自引:0,他引:4  
Turbo码由于其优越的性能已经被IMT-2000确定为首选编码方案。交织器在Turbo码中起着关键性的作用。该文利用分组交织器和随机交织器的优点,设计出一种新型Turbo码交织器(分组随机交织器)。仿真结果显示,在信噪比较低、帧长较短的条件下,这种新型交织器具有比分组交织器和随机交织器更好的性能。  相似文献   

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If the dynamics of an evolutionary differential equation system possess a low-dimensional, attracting, slow manifold, there are many advantages to using this manifold to perform computations for long term dynamics, locating features such as stationary points, limit cycles, or bifurcations. Approximating the slow manifold, however, may be computationally as challenging as the original problem. If the system is defined by a legacy simulation code or a microscopic simulator, it may be impossible to perform the manipulations needed to directly approximate the slow manifold. In this paper we demonstrate that with the knowledge only of a set of “slow” variables that can be used to parameterize the slow manifold, we can conveniently compute, using a legacy simulator, on a nearby manifold. Forward and reverse integration, as well as the location of fixed points are illustrated for a discretization of the Chafee-Infante PDE for parameter values for which an Inertial Manifold is known to exist, and can be used to validate the computational results  相似文献   

6.
Huang  Xin  Yan  Fei  Zhang  Liqiang  Wang  Kai 《Information Systems Frontiers》2021,23(2):269-283
Information Systems Frontiers - Code reuse attacks such as Return-Oriented Programming (ROP) and Jump-Oriented Programming (JOP) are the prevalent attack techniques which reuse code snippets named...  相似文献   

7.
We present the first fully syntactic (i.e., non-interpretation-based) AC-compatible recursive path ordering (RPO). It is simple, and hence easy to implement, and its behaviour is intuitive as in the standard RPO. The ordering is AC-total and defined uniformly for both ground and nonground terms, as well as for partial precedences. More important, it is the first one that can deal incrementally with partial precedences, an aspect that is essential, together with its intuitive behaviour, for interactive applications such as Knuth–Bendix completion.  相似文献   

8.
二维条码的识别方法   总被引:9,自引:3,他引:9  
以QR矩阵码为例,介绍一种实用的二维条码识别算法。首先探讨了二维条码的定位与分割算法,利用Hough变换与Sobel边缘检测把条码图像从原始采集的图像中有效地分割出来;然后分析了条码图像经过光学系统的噪声模型,提出了一种计算点扩展函数标准方差的算法;采用Flourier变换自适应地选取阈值去除噪声导致的无效边界,从而得到条码的基本模块。实验结果表明,该算法具有很好的抗噪性,提高了二维条码的识别率。  相似文献   

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An innovative algorithm for syntactic analysis could be the first step toward placing grammar on a chip.  相似文献   

12.
A Neural Syntactic Language Model   总被引:1,自引:0,他引:1  
This paper presents a study of using neural probabilistic models in a syntactic based language model. The neural probabilistic model makes use of a distributed representation of the items in the conditioning history, and is powerful in capturing long dependencies. Employing neural network based models in the syntactic based language model enables it to use efficiently the large amount of information available in a syntactic parse in estimating the next word in a string. Several scenarios of integrating neural networks in the syntactic based language model are presented, accompanied by the derivation of the training procedures involved. Experiments on the UPenn Treebank and the Wall Street Journal corpus show significant improvements in perplexity and word error rate over the baseline SLM. Furthermore, comparisons with the standard and neural net based N-gram models with arbitrarily long contexts show that the syntactic information is in fact very helpful in estimating the word string probability. Overall, our neural syntactic based model achieves the best published results in perplexity and WER for the given data sets.This work was supported by the National Science Foundation under grant No. IIS-0085940.Editors: Dan Roth and Pascale Fung  相似文献   

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Syntactic parsing: A survey  相似文献   

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The combination of Web services and ontologies is gaining momentum as the potential silver bullets for tomorrows Web, i.e., the Semantic Web. We propose an architectural foundation for managing semantic Web services in dynamic environments. We introduce the concept of community to cater for an ontological organization of Web services. We develop an ontology called community ontology that serves as a template for describing communities of Web services. We also propose a peer-to-peer approach for managing communities in dynamic environments.  相似文献   

16.
In his 1967 lecture notes, Christopher Strachey states that macrogenerators are useful as the only alternative to rewriting the compiler when language extensions are needed. He also states, however, that they deal inappropriately with programs as strings of symbols, ignoring their semantic content, and that they lead to inconvenient syntax and often less transparent code. He concludes that a goal of language designers should be to eliminate the need for macrogeneration. This article attempts to reconcile the contemporary view of syntactic abstraction, which deals with programs at a higher level, with Strachey's views on macrogeneration.Syntactic abstraction has evolved to address the deficiencies of macrogeneration and has, to a large extent, eliminated them. Syntactic abstractions are conveniently expressed, conveniently used, and usually lead to more rather than less transparent code. While a worthwhile goal for language designers is to reduce the need for macrogeneration through the inclusion of an appropriate set of built-in syntactic forms, this article concludes that syntactic abstraction is a valuable tool for programmers to define language extensions that are not anticipated by the language designer or are domain-specific and therefore not of sufficiently general use to be included in the language core.  相似文献   

17.
Dynamic binding, which traditionally has always been associated with Lisp, is still semantically obscure to many. Even though most programming languages favour lexical scope, not only does dynamic binding remain an interesting and expressive programming technique in specialised circumstances, but also it is a key notion in formal semantics. This article presents a syntactic theory that enables the programmer to perform equational reasoning on programs using dynamic binding. The theory is proved to be sound and complete with respect to derivations allowed on programs in dynamic-environment passing style. From this theory, we derive a sequential evaluation function in a context-rewriting system. Then, we further refine the evaluation function in two popular implementation strategies: deep binding and shallow binding with value cells. Afterwards, following the saying that deep binding is suitable for parallel evaluation, we present the parallel evaluation function of a future-based functional language extended with constructs for dynamic binding. Finally, we exhibit the power and usefulness of dynamic binding in two different ways. First, we prove that dynamic binding adds expressiveness to a purely functional language. Second, we show that dynamic binding is an essential notion in semantics that can be used to define exceptions.  相似文献   

18.
针对如何提高代码评审效率的问题,本文提出了BPR-CR2评审者推荐模型.该模型中结合了评审者与代码Pull请求的专业关联性、与Pull请求提出者的社交关联性、与Pull请求的代码路径相关性以及评审者的积极性因素,基于贝叶斯个性化排序的思想学习每个评审者在进行Pull请求选择时的权重偏好,从而能够对每个Pull请求推荐评审者.在Github平台的5个流行项目的数据集上进行了测试,与目前5个典型算法相比,BPR-CR2的性能优于其他算法.  相似文献   

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Despite high expectations, shopbots have yet to significantly facilitate a richer, more satisfying online shopping experience for users. By taking advantage of semantic Web and Web services technologies, however, researchers can overcome current technological limitations and finally realize the shopbot's significant potential  相似文献   

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