Morphological operators to extract channel networks from digital elevation models

The automated extraction of drainage networks includes generation and processing of digital elevation models (DEMs) obtained from the remotely sensed data having stereo viewing capability. The latter aspect generally aims to extract terrain features such as elevation contours and channel networks. In this technical note, the application of morphological operators to extract channel networks from the digital elevation model is described. The methodology is illustrated using a transcendentally generated DEM that bears the spatially distributed regions in grey levels, assumed as the regions of topographic reliefs and the V-shaped crenulations in successive elevation contours. The authors conclude that the adaptation of this approach to extract channel networks from DEM data is straightforward and is simple both algorithmically and computationally.     

Extracting models from source code in software modernization

Model-driven software modernization is a discipline in which model-driven development (MDD) techniques are used in the modernization of legacy systems. When existing software artifacts are evolved, they must be transformed into models to apply MDD techniques such as model transformations. Since most modernization scenarios (e.g., application migration) involve dealing with code in general-purpose programming languages (GPL), the extraction of models from GPL code is an essential task in a model-based modernization process. This activity could be performed by tools to bridge grammarware and MDD technical spaces, which is normally carried out by dedicated parsers. Grammar-to-Model Transformation Language (Gra2MoL) is a domain-specific language (DSL) tailored to the extraction of models from GPL code. This DSL is actually a text-to-model transformation language which can be applied to any code conforming to a grammar. Gra2MoL aims to reduce the effort needed to implement grammarware-MDD bridges, since building dedicated parsers is a complex and time-consuming task. Like ATL and RubyTL languages, Gra2MoL incorporates the binding concept needed to write mappings between grammar elements and metamodel elements in a simple declarative style. The language also provides a powerful query language which eases the retrieval of scattered information in syntax trees. Moreover, it incorporates extensibility and grammar reuse mechanisms. This paper describes Gra2MoL in detail and includes a case study based on the application of the language in the extraction of models from Delphi code.     

Using convert to transform source code

There are a number of reasons why one might wish to transform the source code of an operational program:

• 1 To make the program conform to a standard layout.
• 2 To make the program conform to syntax and semantics standards.
• 3 To improve the performance of the program.

The primary advantage of transforming source code into a standard form is that the programs become easier to maintain. The cost-benefit of standardization is thus realized at a later stage in the lifetime of the programs. Alternatively the cost-benefit of improving performance is immediate. The desirability of transforming source code is affected by several parameters:

• 1 The benefit to be realized from transformation.
• 2 The cost of transformation.
• 3 The time involved in transformation.
• 4 The risk associated with transformation.

If the benefit of transformation is significant, the cost, time and risk associated with the process can be considerably reduced by automating the process. In this paper, application of the CONVERT language to the transformation problem is discussed. CONVERT was developed as a vehicle for writing automatic language and dialect converters. Clearly, the features useful for converters are also applicable when the application involves transformation of source code.     

Fast extraction of high-quality framework-specific models from application code

Framework-specific models represent the design of application code from the framework viewpoint by showing how framework-provided concepts are instantiated in the code. Retrieving such models quickly and precisely is necessary for practical model-supported software engineering, in which developers use design models for development tasks such as code understanding, verifying framework usage rules, and round-trip engineering. Also, comparing models extracted at different times of the software lifecycle supports software evolution tasks. We describe an experimental study of the static analyses necessary to automatically retrieve framework-specific models from application code. We reverse engineer a number of applications based on three open-source frameworks and evaluate the quality of the retrieved models. The models are expressed using framework-specific modeling languages (FSMLs), each designed for an open-source framework. For reverse engineering, we use prototype implementations of the three FSMLs. Our results show that for the considered frameworks and a large body of application code rather simple code analyses are sufficient for automatically retrieving framework-specific models with high precision and recall. Based on the initial results, we refine the static analyses and repeat the study on a larger set of applications to provide more evidence and confirm the results. The refined static analyses provide precision and recall of close to 100% for the analyzed applications. This paper is an extended version of the paper “Automatic extraction of framework-specific models from framework-based application code”, which was published in the proceedings of the Twenty-Second ACM/IEEE International Conference on Automated Software Engineering, 2007.     

Rigorous development process of a safety-critical system: from ASM models to Java code

International Journal on Software Tools for Technology Transfer - The paper presents an approach for rigorous development of safety-critical systems based on the Abstract State Machine formal...     

利用邻域质心投票从分类后影像提取道路中心线

目的 利用分类算法对高分辨率影像中的道路进行分割时,得到的二值图像往往混杂了许多非道路区域,且道路区域呈面状,无法直接应用于生产与研究。针对该问题,提出一种利用邻域质心投票提取道路中心线的算法。方法 首先检测像素在各方向上的连通距离以构建邻域多边形,随后进行质心投票来提取道路的中心线,与此同时估算道路宽度并判断出连通距离较长的方向数目,以排除非道路区域的干扰,最后经形态学处理得到细化的中心线。结果 选取测试图像及具有不同道路分布特征的高分辨率航空影像的分类结果进行实验,并将该算法与Zhang和Couloigner提出的算法进行了对比分析。结果显示,该算法的提取质量为80.6%和79.0%,且计算效率较高,处理实际影像的用时小于参考算法的20%,此外在稳定性及对不同路宽的适应性等多个方面均具有优势。结论 提出一种邻域质心投票算法,该算法能够同时实现传统方法中提纯与中心线提取两个步骤所对应的功能,从分类影像直接提取道路中心线。实验结果表明,该算法能够根据形状特征有效检测道路,且具备一定抗干扰能力,适用于对混杂了非道路区域的高分辨率影像的分类结果进行处理。     

Using mobile code to build a smart kitchen

Software infrastructures for handheld and ubiquitous computing systems help developers tackle many implementation problems. Sun Microsystems recently introduced an infrastructure called Jini. We report on our experiences of using Jini to build a smart kitchen. We found that the central Jini concept of code mobility proved very beneficial offering a simple mechanism for device interoperability and encouraging developers to better structure the software.     

Using dependencies to improve precision of code analysis

Development of dependency analysis methods in order to improve static code analysis precision is considered in this paper. Reasons for precision loss when detecting defects in program source code using abstract interpretation methods are explained. Need for program object dependency extraction and interpretation is justified by numerous real-world examples. Dependency classification is presented. Necessity for aggregate analysis of values and dependencies is considered. Dependency extraction from assignment statements is described. Dependency interpretation based on logic inference using logic and arithmetic rules is proposed. The methods proposed are implemented in defect detection tool Digitek Aegis, significant increase of precision is shown.     

Using profile information to assist classic code optimizations

This paper describes the design and implementation of an optimizing compiler that automatically generates profile information to assist classic code optimizations. This compiler contains two new components, an execution profiler and a profile-based code optimizer, which are not commonly found in traditional optimizing compilers. The execution profiler inserts probes into the input program, executes the input program for several inputs, accumulates profile information and supplies this information to the optimizer. The profile-based code optimizer uses the profile information to expose new optimization opportunities that are not visible to traditional global optimization methods. Experimental results show that the profile-based code optimizer significantly improves the performance of production C programs that have already been optimized by a high-quality global code optimizer.     

Using Stack Overflow content to assist in code review

An essential goal for programmers is to minimize the cost of identifying and correcting defects in source code. Code review is commonly used for identifying programming defects. However, manual code review has some shortcomings: (1) it is time-consuming and (2) outcomes are subjective and depend on the skills of reviewers. An automated approach for assisting in code reviews is thus highly desirable. We present a tool for assisting in code review and results from our experiments evaluating the tool in different scenarios. The tool leveraged content available from professional programmer support forums (eg, StackOverflow.com) to determine potential defectiveness of a given piece of source code. The defectiveness is expressed on the scale of {Likely defective, neutral, unlikely to be defective}. The basic idea employed in the tool is (1) to identify a set P of discussion posts on Stack Overflow such that each p∈P contains source code fragment(s), which sufficiently resemble the input code C being reviewed, and (2) to determine the likelihood of C being defective by considering all p∈P. A novel aspect of our approach is to use document fingerprinting for comparing two pieces of source code. Our choice of document fingerprinting technique is inspired by source code plagiarism detection tools where it has proven to be very successful. In the experiments that we performed to verify the effectiveness of our approach, source code samples from more than 300 GitHub open-source repositories were taken as input. An F1 score of 0.94 has been achieved in identifying correct/relevant results.     

改进的Freeman链码进行人民币的面额识别

针对尺寸法进行人民币的面额识别中,使用Freeman链码进行纸币边界曲线跟踪时出现的断点、漏点、错点及处理数据量大、速度慢的问题,提出一种新的链码定位边界法。首先通过统计纸币轮廓点的横、纵坐标值出现的频率确定链码起始点;然后定义一种新的多方向链码以解决图像边界点的间断问题;最后利用之前链码预测之后链码以减少漏点、错点,减少噪声对曲线跟踪的影响。实验结果表明,该方法用于纸币识别,识别率达到了96.159%以上,计算复杂度降低,识别速度提高,是一种有效的图像边界提取方法。     

Using combinatory categorial grammar to extract biomedical information

Extracting information from biology databases manually can be an overwhelming task. GenBank, the US National Institutes of Health database containing all publicly available DNA sequences, has more than 14 billion bases in 13 million genetic-sequence records. Medline, a literature database available through PubMed, has over 11 million journal citations. In a May 2001 search request for "cytokine" (regulatory proteins in the immune system), PubMed returned 296556 articles. Given the quantity and complexity of biomedical literature, demands for computational tools to extract specific information are increasing. The author reviews biomedical information extraction methods and presents research done by KAIST's natural language processing group on a system that shows encouraging performance using combinatory categorial grammar as a natural language grammar formalism.     

基于深度图网络的编译器向量化启发式算法

针对现有的深度学习模型将程序代码考虑为一个串行序列而错失较大性能优化空间的问题,提出了一种新的基于深度图网络的程序启发式优化方法.该方法采用图神经网络对程序的数据和依赖图进行建模,自动从源代码中抽取有效程序特征,然后再将抽取的特征输入下游模型进行循环向量化参数预测.在LLVM循环向量测试集上,所提出的方法取得了2.08倍的加速比,与现有方法相比提高了12％的性能.     

Using models to improve stereo reconstruction

The authors propose the combination of photometric and stereometric information to solve the stereo vision problem in the case of a man-made environment. A method to introduce geometrical models in the stereo process in order to improve the accuracy of the depth measurement and to extend the depth map to points where no measurements have been made is presented. This method is based on a parameterization of the object surfaces and relies on a systematic comparison of the result of a stereo process with the photometric (or gray-level) image. The proposed approach improves the accuracy of the stereo information and its density by introducing a hypothesis on the object surfaces. Two kinds of hypothesis are developed: planar and quadratic objects. Reconstructions of complex scenes are given     

Using Wikipedia concepts and frequency in language to extract key terms from support documents

In this paper, we present a new key term extraction system able to handle with the particularities of “support documents”. Our system takes advantages of frequency-based and thesaurus-based approaches to recognize two different classes of key terms. On the one hand, it identifies multi-domain key terms of the collection using Wikipedia as knowledge resource. On the other hand, the system extracts specific key terms highly related with the context of a support document. We use the frequency in language as a criterion to detect and rank such terms. To prove the validity of our system we have designed a set of experiment using a Frequently Asked Questions (FAQ) collection of documents. Since our approach is generic, minor modifications should be undertaken to adapt the system to other kind of support documents. The empirical results evidence the validity of our approach.     

Using software architecture for code testing

Our research deals with the use of software architecture (SA) as a reference model for testing the conformance of an implemented system with respect to its architectural specification. We exploit the specification of SA dynamics to identify useful schemes of interactions between system components and to select test classes corresponding to relevant architectural behaviors. The SA dynamics is modeled by labeled transition systems (LTSs). The approach consists of deriving suitable LTS abstractions called ALTSs. ALTSs offer specific views of SA dynamics by concentrating on relevant features and abstracting away from uninteresting ones. Intuitively, deriving an adequate set of test classes entails deriving a set of paths that appropriately cover the ALTS. Next, a relation between these abstract SA tests and more concrete, executable tests needs to be established so that the architectural tests derived can be refined into code-level tests. We use the TRMCS case study to illustrate our hands-on experience. We discuss the insights gained and highlight some issues, problems, and solutions of general interest in architecture-based testing.     

Using linguistic features to automatically extract web page title

Existing methods for extracting titles from HTML web page mostly rely on visual and structural features. However, this approach fails in the case of service-based web pages because advertisements are often given more visual emphasize than the main headlines. To improve the current state-of-the-art, we propose a novel method that combines statistical features, linguistic knowledge, and text segmentation. Using annotated English corpus, we learn the morphosyntactic characteristics of known titles and define a part-of-speech tag patterns that help to extract candidate phrases from the web page. To evaluate the proposed method, we compared two datasets Titler and Mopsi and evaluated the extracted features using four classifiers: Naïve Bayes, k-NN, SVM, and clustering. Experimental results show that the proposed method outperform the solution used by Google from 0.58 to 0.85 on Titler corpus and from 0.43 to 0.55 on Mopsi dataset, and offers a readily available solution for the title extraction problem.     

主题与子事件发现的多文档自动文摘

提出了一种基于主题与子事件抽取的多文档自动文摘方法。该方法突破传统词频统计方法,除考虑词语频率、位置信息外,还将词语是否为描述文本集合的主题和子事件作为因素,提取出了8个基本特征,利用逻辑回归模型预测基本特征对词语权重的影响,计算词语权重。通过建立句子向量空间模型给句子打分,结合句子分数和冗余度产生文摘。对N-gram同现频率、主题词覆盖率和高频词覆盖率3种不同参数,分别在Coverage Baseline、Centroid-Based Summary和Word Mining based Summary（WMS）3种不同文摘系统下所产生的文摘质量,进行了对比实验,结果表明WMS系统在多方面具有优越的性能。     

Using SCL to specify and check design intent in source code

Software developers often fail to respect the intentions of designers due to missing or ignored documentation of design intent. SCL (Structural Constraint Language) addresses this problem by enabling designers to formalize and confirm compliance with design intent. The designer expresses his intent as constraints on the program model using the SCL language. The SCL conformance checking tool examines developer code to confirm that the code honors these constraints. This paper presents the design of the SCL language and its checker, a set of practical examples of applying SCL, and our experience with using it both in an industrial setting and on open-source software.