面向专家示例的Stack Overflow本体构造和推理研究

Stack Overflow是一个计算机领域的IT技术问答网站,为了获取问答网站中的专家示例并将其应用于API挖掘中。首先采用Scrapy爬虫框架技术获取Stack Overflow问答网站中的结构化数据,并存储在关系模式中;再使用本体建模工具Protégé构建本体,然后使用D2RQ工具实现对关系数据库的知识抽取,将关系模式转换为三元组形式的本体模型;同时,提出了一个面向专家示例的子本体抽取算法,用于从原本体中抽取出专家示例推理相关的子本体,并提出了若干条专家示例推理规则,能推导出专家所编写的代码示例。实验结果证明,从Stack Overflow本体模型中抽取的专家示例能提高API调用序列挖掘的准确率。

Detection of Buffer Overflow Attacks with Memoization-based Rule Set

Different abnormalities are commonly encountered in computer network systems.These types of abnormalities can lead to critical data losses or unauthorized access in the systems.Buffer overflow anomaly is a prominent issue among these abnormalities,posing a serious threat to network security.The primary objective of this study is to identify the potential risks of buffer overflow that can be caused by functions frequently used in the PHP programming language and to provide solutions to minimize these risks.Static code analyzers are used to detect security vulnerabilities,among which SonarQube stands out with its extensive library,flexible customization options,and reliability in the industry.In this context,a customized rule set aimed at automatically detecting buffer overflows has been developed on the SonarQube platform.The memoization optimization technique used while creating the customized rule set enhances the speed and efficiency of the code analysis process.As a result,the code analysis process is not repeatedly run for code snippets that have been analyzed before,significantly reducing processing time and resource utilization.In this study,a memoization-based rule set was utilized to detect critical security vulnerabilities that could lead to buffer overflow in source codes written in the PHP programming language.Thus,the analysis process is not repeatedly run for code snippets that have been analyzed before,leading to a significant reduction in processing time and resource utilization.In a case study conducted to assess the effectiveness of this method,a significant decrease in the source code analysis time was observed.

基于数据挖掘的专业可信回答者个性化推荐——以Stack Overflow问答社区为例

针对问答社区中问题不能得到及时、有效解答的现状,文章以Stack Overflow问答社区为例,首先介绍了问答社区数据的采集与预处理情况;然后,通过挖掘学习者信息,得到专业可信回答者、高信誉回答者和徽章回答者三种潜在回答者;最后,实施了三种回答者推荐并对比了推荐性能。实验结果表明,与高信誉回答者推荐和徽章回答者推荐相比,考虑回答质量和专业相关性的专业可信回答者推荐具有更高的准确率和召回率,其推荐性能更优。实施基于数据挖掘的专业可信回答者个性化推荐,能有效缓解问答社区的信息过载问题,有助于建设更高效的网络学习社区环境。

Stack Overflow上机器学习相关问题的大规模实证研究

为了调查机器学习相关主题分布和发展趋势,从在线问答网站Stack Overflow上,利用过滤标签,从4 178多万帖子中提取出60 028个与机器学习相关的问题帖.通过分析问题帖,统计各个机器学习平台的讨论量,发现Scikit-learn、TensorFlow、Keras是前3位频繁被讨论的机器学习平台,占总讨论量的58%.为了进一步分析机器学习相关讨论主题,进行潜在狄利克雷分布(LDA)主题模型训练,提出自适应LDA中的主题数渐进搜索方法,采用主题一致性系数评估输出结果,获得主题最佳数量,从而发现9个讨论主题,分属3个类别:代码相关、模型相关、理论相关.基于主题中问题帖的浏览数、评论数,分析不同主题的流行度和回答困难程度.

Stack Overflow的缺陷代码特征分析与相似缺陷检测

目前在软件代码缺陷审查以及缺陷预测中,研究人员对源代码进行分析研究却忽略了代码的缺陷信息.本文通过对缺陷信息进行分析,发现缺陷信息对于相似缺陷的检测有着重要的参考价值.基于这一思想,本文分析软件缺陷社区Stack Overflow中关于缺陷代码的信息,提出一种基于缺陷代码特征分析的相似缺陷检测方法.该方法首先对缺陷报告进行LDA主题分析并将缺陷报告分类到不同的主题(类别)中,统计得到高频缺陷类别;其次对于高频缺陷类别的缺陷代码提取特征;最后根据缺陷代码特征构建相似缺陷检测模型.为了验证相似缺陷检测模型的有效性,针对数据操作缺陷数据构建诊断模型并对该模型进行实证,实验结果表明该方法对检测其他代码中相似缺陷有较好的效果.

基于CBOW-LDA主题模型的Stack Overflow编程网站热点主题发现研究

Stack Overflow是一个热门的国外编程问答网站,通过对该网站编程提问帖的问题文本进行文本语义挖掘,能获析用户关注的编程热点。由于研究对象所代表的短文本信息具有高维性及分布不均的特点,易导致主题获取不明晰。文中提出一种基于LDA(Latent Dirichlet Allocation)主题模型的CBOW-LDA建模方法,该方法对目标语料进行相似词聚类后再完成主题建模,能有效降低文本输入维度,使主题分布更明确。采集Stack Overflow网站上2010-2015年的问题帖数据集POST,并对其进行实验,同等主题数下采用文本建模中衡量模型性能的评价指标困惑度(Perplexity)来度量算法在不同数据集容量维度下的性能。结果表明,与现有的基于词频权重的词量化主题建模TFLDA方法相比,CBOW-LDA方法的困惑度更低,在实验语料下的困惑度降低约4.87%,证明了所提算法的性能更好。采用CBOW-LDA方法对Stack Overflow进行热点挖掘,同时使用TF-LDA方法进行对比实验,建立手工标注的标准评测集对两种方法获取的热门主题和热搜词汇进行查全率、查准率及F1值的判定,结果证实CBOW-LDA表现更佳,其热点挖掘效果较好。由实验结果可知,Java为该编程网站提问帖中最热门的主题,而C和Javascript则为该网站用户提问中被提及得最频繁的词汇。

基于Stack Overflow的数据库相关主题分析

数据库管理系统虽是一种较为成熟的软件系统,但开发人员在应用数据库系统进行数据管理以及数据分析时还是会遇到各种问题,因此会在Stack Overflow之类的问答论坛上寻求解决方法。文中获取了Stack Overflow上94473条与数据库相关的问题,应用LDA主题模型将这些问题归为25个主题,结果显示开发者的问题可归为"表""SQL""SELECT"等主题。通过研究与数据库相关的不同主题的流行度和困难程度发现,"SQL"主题相关的问题较为流行。除此以外,文中还分别研究了3种不同的数据库,即MySQL,Oracle和MongoDB,分析了与不同数据库系统相关的问题的主题分布。文中的研究成果有助于了解数据库开发者所面临的挑战,从而为数据库系统版本更新、数据库课程教学内容的设置,甚至是数据库领域的研究问题提供参考。

中外技术问答社区的实证对比研究与启示——以CSDN和Stack Overflow为例

社会化问答社区是当前网络用户进行知识交流的重要平台,而技术问答社区则是专注于技术知识交流的问答社区。本文选取国内外最具有代表性的两大技术问答社区进行对比研究,旨在指出国内技术问答社区的优势与不足,并为国内技术问答社区的进一步发展与优化提出针对性建议。本文分别从社区活跃度、社区主题、社区问题质量、用户体验和社交属性5个维度开展了对比分析,并利用相关性分析,分析并比较了在两个问答社区中影响问题被回答情况的相关因素。本文发现两大技术问答社区在活跃度、用户提问与回答情况等方面存在显著差异,并从优化问题质量评价机制、提高用户回答积极性、优化激励机制以及强化社交属性等方面为我国技术问答社区的进一步发展与完善给出了建议。

Stack Overflow系统的特征融合答案推荐策略

针对Stack Overflow系统中用户寻找问题答案效率低的问题,提出一种基于标题相似度、描述相似度、标签相似度、语义相似度的特征融合答案推荐策略(FIARS)。从Stack Overflow网站中抽取“问题与答案”语料集,对答案进行去重处理,建立问题索引和问题对应的答案集索引;采用余弦相似度计算新问题与语料库中问题在标题、标签、问题描述等维度上的相似度,并构建语义模型计算语义相似度;基于这些相似度筛选出最佳的“问题与答案”候选集并把答案推荐给用户。为了验证策略的可行性和有效性,使用Stack Overflow真实数据集进行分析实验,实验结果表明该策略能够较大地提高答案推荐的准确率。

Influence of two inlets of the Luzon overflow on the deep circulation in the northern South China Sea

An inverse reduced-gravity model is used to simulate the deep South China Sea(SCS)circulation.A set of experiments are conducted using this model to study the influence of the Luzon overflow through the two inlets on the deep circulation in the northern SCS.Model results suggest that the relative contribution of these inlets largely depends on the magnitude of the input transport of the overflow,but the northern inlet is more efficient than the southern inlet in driving the deep circulation in the northern SCS.When all of the Luzon overflow occurs through the northern inlet the deep circulation in the northern SCS is enhanced.Conversely,when all of the Luzon overflow occurs through the southern inlet the circulation in the northern SCS is weakened.A Lagrangian trajectory model is also developed and applied to these cases.The Lagrangian results indicate that the location of the Luzon overflow likely has impacts upon the sediment transport into the northern SCS.

OverflowDungeon:一种新颖的溢出攻击防护系统

溢出攻击是网络上威胁最大的一种攻击方式,现有的防护技术存在不同的缺陷。本文提出并实现了一种新颖的防护机制,它从阻止溢出攻击产生破环性效果入手,抑制攻击行为,该方式不需要修改编译器,或修改操作系统,具有很高的实用性,它采用了统计方式,可有效防护 Dummy return 攻击技术。试验结果表明,系统不仅能有效地阻止溢出攻击,在效率方面相对于其他方式也有显著优势。

在Stack Overflow平台上关于安卓应用程序接口群体讨论的探索性研究（英文）

如今尽管安卓的官方文档内容越来越丰富,但是越来愈多的安卓开发人员更愿意在Stack Overflow等问答社区中寻求帮助,而不是在安卓官方文档中寻找答案。对此,一些研究者对官方文档的局限性进行研究,并提出改进方法,但是他们很少有从第三方开发者的需求角度对这个问题进行研究。本文采用一种交叉验证的方法从API(应用程序接口)文档维护人员和第三方用户的多维视角研究这个问题,提出了一种结合人工检测和调查问卷的混合方法来探索不同利益相关者关注点的不同。在人工检测过程中我们对1000个Stack Overflow中的帖子进行分析;在线调查问卷过程中共收到了319份问卷结果。通过人工检测和调查问卷的相互验证,我们发现第三方用户更关心如何使用API,但是官方文档更多的对API的功能进行描述,缺少如何使用API的示例。此外,我们发现了官方文档的9个缺陷,并列举了12个可以提高API文档的方式。

Multi-Level Approach of the Ecotoxicological Impact of a Combined Sewer Overflow on a Peri-Urban Stream

In periurban zones, urban wet weather discharges have been recognized as the most significant vector of pollution in aquatic environments. The discharge of this water without treatment into the aquatic environment could present an ecotoxicological risk for biocenosis. The aim of the INVASION project is to assess the potential ecotoxicological impact of a combined sewer overflow (CSO) on a peri-urban stream. A comparative study between upstream and downstream areas of the CSO allowed observing significant effects of this overflow on the river. We studied three layers of stream: surface water, benthic layer and hyporheic layer. To characterize the potential ecotoxicological risk of water and sediments, we used a battery of 4 bioassays: Daphnia magna, Vibrio fischeri, Brachionus calyciflorus and Heterocypris incongruens. In parallel, we measured the physico-chemical parameters: ammonium (NH4+), chromium (Cr), copper (Cu) and lead (Pb). An ecological risk is greatest for the hyporheic zone in downstream river, particularly for the solid phase. These results corroborated with the physico-chemical data obtained.

On the Importance of Sanitary Sewer Overflow on the Total Discharge of Microplastics from Sewage Water

The paper provides an investigation and understanding of the significance of various wastewater flows on microplastics retainment and emission to the environment. WWTPs and sewer overflows as an important pathway of microplastics to the environment are assessed by considering the removal of microplastics in WWTPs with different treatment processes and several sewer overflow types and their contribution to microplastic loads to recipients. On the example of the Baltic Sea basin, presented results indicate a considerable discharge of microplastic from WWTPs despite the relatively good overall removal efficiency. Results show that the discharge of microplastics from sewer overflows can be in the same magnitude as from treated wastewater although the total flow is much lower than that of treated wastewater. Sewer overflow events frequently occur and are expected to increase due to climate change and urbanization, unless infrastructure is adapted. At the same time, sewer overflows are often neglected in conventional wastewater handling.

Geek Talents:Who are the Top Experts on GitHub and Stack Overflow?

In the field of Computer Science,software developers need to use a wide array of social collaborative platforms for learning and cooperating.The most popular ones are GitHub and Stack Overflow.Existing platforms only support search queries to extract relevant repository information from GitHub,or questions and answers from Stack Overflow.This ignores the valuable coder-related part-who are the top experts(geek talents)in a specific area?This information is important to companies,open source projects,and to those who want to learn from an expert role model.Thus,how to find the right developers is quite a crucial yet challenging problem.Most of the current works mainly focus on recommending experts in a particular software engineering task and ignore the relationship between developers within different projects.In this paper,we propose a novel technique that automatically identifies geek talents from GitHub,Stack Overflow,and across both communities.The results show that our work performs well at recommending proper developers in diverse areas.

An Efficient Overflow Detection and Correction Scheme in RNS Addition through Magnitude Evaluation

Number Systems are media for representing numbers;the popular ones being the Weighted Number Systems (WNS), which sometimes propagate carries during arithmetic computations. The other category, Un-Weighted Number Systems, of which the Residue Number System (RNS) belongs, do not carry weights but have not yet found widespread usage in general purpose computing as a result of some challenges;one of the main challenges of RNS is overflow detection and correction. The presence of errors in calculated values due to such factors as overflow means that systems built on this number system will continue to fail until serious steps are taken to resolve the issue. In this paper, a scheme for detecting and correcting overflow during RNS addition is presented. The proposed scheme used mixed radix digits to evaluate the magnitude of the addends in order to detect the occurrence of overflow in their sum. The scheme also demonstrated a simplified technique of correcting the overflow in the event that it occurs. An analysis of the hardware requirements and speed limitations of the scheme showed that it performs considerably better in relation to similar state of art schemes.

Mechanism and prevention method of drill string uplift during shut-in after overflow in an ultra-deep well

Drill string will sustain large uplift force during the shut-in period after gas overflow in an ultra-deep well, and in serious case, it will run out of the wellhead. A calculation model of uplift force was established to analyze dynamic change characteristics of the uplift force of drill string during the shut-in period, and then a management procedure for the uplift risk during the shut-in period after gas overflow in the ultra-deep well was formed. Cross section method and pressure area method were used to analyze the force on drill string after shut-in of well, it was found that the source of uplift force was the "fictitious force" caused by the hydrostatic pressure in the well. When the fictitious force is in the opposite direction to the gravity, it is the uplift force. By adopting the theory of annular multiphase flow, considering the effects of wellbore afterflow and gas slippage, the dynamic change of the pressure and fluid in the wellbore and the uplift force of drill string during the shut-in period were analyzed. The magnitude and direction of uplift force are related to the length of drill string in the wellbore and shut-in time, and there is the risk of uplift of drill string when the length of drill string in the wellbore is smaller than the critical drill string length or the shut in time exceeds the critical shut in time. A set of treatment method and process to prevent the uplift of drill string is advanced during the shut-in period after overflow in the ultra-deep well, which makes the risk management of the drill string uplift in the ultra-deep well more rigorous and scientific.

Program Slicing Based Buffer Overflow Detection

The development of the information technology has brought threats to human society when it has influenced seriously the global politics, economics and military etc. But among the security of information system, buffer overrun vulnerability is undoubtedly one of the most important and common vulnerabilities. This paper describes a new technology, named program slicing, to detect the buffer overflow leak in security-critical C code. First, we use slicing technology to analyze the variables which may be with vulnerability and extract the expressions which will bring memory overflow. Secondly, we utilize debug technology to get the size of memory applied by the variable and the size of memory used for these code segments (the slicing result) further. Therefore we can judge whether it will overflow according to the analysis above. According to the unique excellence of program slicing performing in the large-scale program’s debugging, the method to detect buffer overrun vulnerability described in this paper will reduce the workload greatly and locate the code sentences affected by corresponding variable set quickly, particularly including the potential vulnerability caused by parameter dependence among the subroutines.

Risk Assessment of Rainwater Overflow from Lake Warouwaye in the Case of a Ten-Year Rainfall in Yeumbeul North, Senegal

This study is a part of a global approach in which, the main purpose is to understand the reasons behind the upsurge of flood events in the peri-urban area of the city of Dakar. Hydrological and hydraulics simulations were carried out to assess the risks of overflowing of the Lake Warouwaye after a so-called exceptional rain. Data were collected through field surveys, as well as site observations of dwellings before and after rain episodes. The simulations were performed using EPA’s Storm Water Management Model (SWMM) software with input data obtained from sub-software and supervisory applications such as Google Earth, Excel, and Global Mapper. The simulation results show factors of natural and anthropogenic origin may contribute to dysfunction hydrological elements such as the watershed capacity to drain and store water. In light of the results of this study, institutional governance efforts are to be made and to be sustained in order to reverse the tendency to occupy rainwater natural flow channels. It will also be necessary to involve the first actors who are the potential victims of flooding caused by the recurrent overflow of reservoirs.

Modelling the Influence of Air Jet Configurations on Non-Woven Steel Fibre Mixing in the Melt Overflow Process

The mixing of non-woven steel fibres in melt overflow process for use in automotive muffler systems was simulated. The aim was to identify optimum parameters for achieving a good fibre mix. Numerical models of mixing chambers of melt overflow process were developed. Multiphysics analyses involving heat transfer, fluid flow and particle tracking were carried out using COMSOL code. The influence of air jet configurations on the fibre distribution was studied. The fibres settled on the moving bed within the mixing chamber were examined for their uniformity. The effect of additional air jets to the existing chamber in a range of regions was explored. An optimum configuration was identified by analyzing the compactness of the particle clusters deposited in the simulation and validated using pixel data acquired from real time imaging. The results showed that by employing dual air jets at the front end of the chamber, the density of the fibre material has improved. We conclude that through multi-physics modelling, it was possible to identify the optimum air-jet configurations leading to fibre uniformity and its distribution. This work also paves the way for incorporating a vision system to evaluate fibre density in real time.