盲源信号分离及其发展

盲源信号分离是信号处理学界和神经网络学界所共同关注的一个热点研究问题,主要介绍了盲源信号分离的基本数学原理和基本模型、求解问题的步骤;以基于高阶累积量和信息论准则的各种典型学习算法为主要对象,对其各种典型方法的数学理论以及特点做了分析,介绍了现在的研究进展,并指出进一步的研究方向。     

Open source software and the algorithm visualization community

Algorithm visualizations are widely viewed as having the potential for major impact on computer science education, but their quality is highly variable. We report on the software development practices used by creators of algorithm visualizations, based on data that can be inferred from a catalog of over 600 algorithm visualizations. Since nearly all are free for use and many provide source code, they might be construed as being open source software. Yet many AV developers do not appear to have used open source best practices. We discuss how such development practices might be employed by the algorithm visualization community, and how they might lead to improved algorithm visualizations in the future. We conclude with a discussion of OpenDSA, an open-source project that builds on earlier progress in the field of algorithm visualization and hopes to use open-source procedures to gain users and contributors.     

Network ties and the success of open source software development

Prior network-based research on open source software (OSS) development has focused on the benefit of network ties and assumed all network ties play the same role. We adopt a fine-grained view of network relations to investigate the impact of network ties on the success of OSS development. Through examining the development of OSS projects hosted by SourceForge, we find that co-membership among project teams is an effective mechanism for building network ties, through which knowledge and expertise flows across projects in OSS community and, therefore, contributes to the success of OSS development. However, network ties among projects not only confer benefit, but also incur various cost, and due to the different growth patterns of cost and benefit, network ties have a diminishing return to project success. In addition, we find network ties of leader–follower type and follower–leader type are more beneficial to OSS success than other types of ties, and network ties connecting to projects of later development stages are more beneficial than those connecting to projects of earlier stages. Our study provides useful guidelines and suggestions as to how to leverage the knowledge and expertise of others for successful development of OSS projects.     

Open source software: A community of altruists

To learn about what drives people to devote their time and expertise to creating and supporting free/open source software, a survey with Likert-scaled items measuring different types of motivations was sent to contributors of several open source projects. Open-ended comments were used to illustrate the Likert-scaled items and open-ended questions allowed respondents to express their reasons for participating in these open source communities. Results indicate that the open source contributors (n = 110, 38 paid to work on OSS projects and 72 volunteers) are motivated primarily by a sense of altruism as well as the desire to create and learn. Payment did not significantly impact the reasons for contributing to OSS projects. The comments and open-ended questions validated the findings and indicated that building a “Utopian” community – the desire to help for the greater good worldwide – is one of the most important motivators. Also, respondents revealed that they join and persist as members of open source communities because they enjoy the freedom to create and share free software, tools and knowledge with others inside and outside the community.     

Open‐source learning management systems: a predictive model for higher education

The present study investigated the role of pedagogical, technical, and institutional profile factors in an institution of higher education's decision to select an open‐source learning management system (LMS). Drawing on the results of previous research that measured patterns of deployment of open‐source software (OSS) in US higher education and the relative importance of specific selection criteria when considering an OSS LMS, a Web survey was conducted among 285 Chief Information Officers and Chief Academic Officers from a variety of US institutions to determine patterns of OSS LMS deployment, as well as the influence of specific selection criteria. Binary logistic regression analysis revealed Carnegie Classification, institutional governance, previous experience with OSS, focus on student learning, and the commitment to organizational self‐reliance to be key influencers in the OSS LMS selection decision. The implications of these findings for future research and for institutional decision‐making are discussed.     

化学信息学与开源软件

化学信息学研究需要性能强大而又能随时修订的、开放性的软件工具。通过回顾自由软件到开源软件的发展历史,展示开源式程序开发的丰富成就,包括操作系统如Linux、社区如SourceForge和我国的共创软件联盟等,澄清与copyright针锋相对的copyleft式版权概念,介绍并比较多种软件许可证,对开源软件的发展机制进行简要分析,认为开源软件是满足化学信息学要求的最佳选择。     

Open source content contributors’ response to free-riding: The effect of personality and context

We address concerns about the sustainability of the open source content model by examining the effect of external appropriation, whereby the product of open source contributors’ efforts is monetized by a party that did not contribute to the project, on intended effort withdrawal (reduction in contribution level). We examine both the personality of contributors and their contextual motivations to contribute, using a scenario-based survey of Wikipedia contributors. The findings suggest that perceived justice of the open source license terms, and intrinsic motivations are both negatively related with effort withdrawal intentions. Moreover, we find that the effect of the fairness personality trait on effort withdrawal is stronger for individuals who are low in perceived justice and weaker for individuals high in justice. The findings of factors predicting effort withdrawal contribute to the open source literature, which tends to focus on contribution and motivations, but not on what impacts changes in individual contribution levels.     

开源软件社区知识协作网络核心开发者识别

开源软件社区中开发者是流动的,有效识别出核心开发者并对其采取保护措施能够更好地促进社区集体智慧涌现.以开源软件项目AngularJS为例,通过获取开发者在GitHub上的提交记录,抽取开发者协作关系构建知识协作网络,运用社会网络分析的方法,在原有度中心性和介数中心性指标的基础上,将开发者节点的社团结构考虑进来提出新的评价指标.采用TOPSIS多属性决策方法进行核心开发者识别.仿真模拟核心开发者的流失,探究识别效果.研究发现:考虑社团结构的指标和以往指标识别出的核心开发者具有较大的相似性,和真实名单对比均具有一定的准确性,但在重要性排序上考虑社团结构的指标体系识别效果更显著.     

Investigating recognition-based performance in an open content community: A social capital perspective

As the open source movement grows, it becomes important to understand the dynamics that affect the motivation of participants who contribute their time freely to such projects. One important motivation that has been identified is the desire for formal recognition in the open source community. We investigated the impact of social capital in participants’ social networks on their recognition-based performance; i.e., the formal status they are accorded in the community. We used a sample of 465 active participants in the Wikipedia open content encyclopedia community to investigate the effects of two types of social capital and found that network closure, measured by direct and indirect ties, had a significant positive effect on increasing participants’ recognition-based performance. Structural holes had mixed effects on participants’ status, but were generally a source of social capital.     

Beyond free software: An exploration of the business value of strategic open source

The phenomenon of open source software (OSS) has been well studied from the software development perspective, but it has received much less attention from the perspective of business value. Nevertheless, OSS, when viewed as a value creation process rather than ‘free’ software, provides businesses with value through access to knowledge and innovation capacity resident in online communities. This conceptualisation, which we label ‘strategic open source’ requires firms to rethink their strategy and processes as there is a shift in focus from ownership to openness and collaboration with external parties. Nonetheless, the emergence of OSS poses a puzzle for conceptions of organisational theory. Therefore, a theorising process is needed in order to develop a deeper understanding of how value is created and captured with OSS. Using a field study of eleven European firms, this paper explores the creation and capture of business value from strategic open source. The findings reveal that while decision makers look to open innovation initiatives like OSS for value creation and capture, there is still a desire to remain self reliant, resulting in collaborative design (of external innovations) rather than collaborative decision making with value network partners in relation to how such innovations would help create and capture value within firms.     

A systematic review of research on open source software in commercial software product development

Context

The popularity of the open source software development in the last decade, has brought about an increased interest from the industry on how to use open source components, participate in the open source community, build business models around this type of software development, and learn more about open source development methodologies. There is a need to understand the results of research in this area.

Objective

Since there is a need to understand conducted research, the aim of this study is to summarize the findings of research that has ben carried out on usage of open source components and development methodologies by the industry, as well as companies’ participation in the open source community.

Method

Systematic review through searches in library databases and manual identification of articles from the open source conference. The search was first carried out in May 2009 and then once again in May 2010.

Results

In 2009, 237 articles were first found, from which 19 were selected based on content and quality, and in 2010, 76 new articles were found from which four were selected. Twenty three articles were identified in total.

Conclusions

The articles could be divided into four categories: open source as part of component based software engineering, business models with open source in commercial organization, company participation in open source development communities, and usage of open source processes within a company.     

Building a next generation Internet with source address validation architecture

The IP packet forwarding of current Internet is mainly destination based. In the forwarding process, the source IP address is not checked in most cases.This causes serious security, management and accounting problems. Based on the drastically increased IPv6 address space, a ＂source address validation architecture＂ （SAVA） is proposed in this paper, which can guarantee that every packet received and forwarded holds an authenticated source IP address. The design goals of the architecture are lightweight, loose coupling, ＂multi-fence support＂ and incremental deployment. This paper discusses the design and implementation for the architecture, including inter-AS, intra-AS and local subnet. The performance and scalability of SAVA are described. This architecture is deployed into the CNGI-CERNET2 infrastructure a large-scale native IPv6 backbone network of the China Next Generation Internet project. We believe that the SAVA will help the transition to a new, more secure and dependable Internet.     

A systematic literature review on the barriers faced by newcomers to open source software projects

ContextNumerous open source software projects are based on volunteers collaboration and require a continuous influx of newcomers for their continuity. Newcomers face barriers that can lead them to give up. These barriers hinder both developers willing to make a single contribution and those willing to become a project member.ObjectiveThis study aims to identify and classify the barriers that newcomers face when contributing to open source software projects.MethodWe conducted a systematic literature review of papers reporting empirical evidence regarding the barriers that newcomers face when contributing to open source software (OSS) projects. We retrieved 291 studies by querying 4 digital libraries. Twenty studies were identified as primary. We performed a backward snowballing approach, and searched for other papers published by the authors of the selected papers to identify potential studies. Then, we used a coding approach inspired by open coding and axial coding procedures from Grounded Theory to categorize the barriers reported by the selected studies.ResultsWe identified 20 studies providing empirical evidence of barriers faced by newcomers to OSS projects while making a contribution. From the analysis, we identified 15 different barriers, which we grouped into five categories: social interaction, newcomers’ previous knowledge, finding a way to start, documentation, and technical hurdles. We also classified the problems with regard to their origin: newcomers, community, or product.ConclusionThe results are useful to researchers and OSS practitioners willing to investigate or to implement tools to support newcomers. We mapped technical and non-technical barriers that hinder newcomers’ first contributions. The most evidenced barriers are related to socialization, appearing in 75% (15 out of 20) of the studies analyzed, with a high focus on interactions in mailing lists (receiving answers and socialization with other members). There is a lack of in-depth studies on technical issues, such as code issues. We also noticed that the majority of the studies relied on historical data gathered from software repositories and that there was a lack of experiments and qualitative studies in this area.     

A framework for creating hybrid-open source software communities

Abstract The open source software (OSS) model is a fundamentally new and revolutionary way to develop software. The success of the OSS model is also setting the stage for a structural change in the software industry; it is beginning to transform software industry from manufacturing to a service industry. Despite the success of the OSS model, for‐profit organizations are having difficulty building a business model around the open source paradigm. Whereas there are some isolated empirical studies, little rigorous research has been done on how traditional organizations can implement and benefit from OSS practices. This research explores how organizations can foster an environment similar to OSS to manage their software development efforts to reap its numerous advantages. Drawing on organizational theory, we develop a framework that guides the creation and management of a hybrid‐OSS community within an organization. We discuss the implications of this framework and suggest areas for future research.     

基于神经网络的四元球面阵空间声源定向系统

针对移动机器人的目标声源定向问题,应用四元球面麦克风阵列建立了一套空间声源定向系统。为了解决通过阵列的时延值预测出目标声源方向的问题,提出了神经网络算法,并设计了双隐层BP神经网络。通过Matlab仿真验证了该网络可以实现近场和远场的声源定向,并在机器人本体上进行了实验测试,证明了该系统的实用性。     

The open source software phenomenon: Characteristics that promote research

Since the turn of the century, open source software has triggered a vast volume of research. In this essay, based on a brief review of selected work, we show that research in many different fields and disciplines of the social sciences have shed light on the phenomenon. We argue that five characteristics make the phenomenon particularly attractive to examination from various fields and disciplines using a plethora of research methods: (1) impact: open source software has an extensive impact on the economy and society; (2) theoretical tension: the phenomenon deviates sharply from the predictions and explanations of existing theory in different fields; (3) transparency: open source software has offered researchers an unprecedented access to data; (4) communal reflexivity: the community of open source software developers frequently engage in a dialog on its functioning (it also has its own research community); (5) proximity: the innovation process in open source software resembles knowledge production in science (in many instances, open source software is an output of research processes). These five characteristics also promote a transdisciplinary research dialog. Based on the experience of open source software research, we propose that phenomena-driven transdisciplinary research provides an excellent context to promote greater dialog between disciplines and fields. Moreover, we propose that the recent diffusion of the open source software model of innovation to other areas than software calls for new research and that the field of information systems has an important role to play in this future research agenda.     

Revisiting Linus’s law: Benefits and challenges of open source software peer review

Open source projects leverage a large number of people to review products and improve code quality. Differences among participants are inevitable and important to this collaborative review process—participants with different expertise, experience, resources, and values approach the problems differently, increasing the likelihood of finding more bugs and fixing the particularly difficult ones. To understand the impacts of member differences on the open source software peer review process, we examined bug reports of Mozilla Firefox. These analyses show that the various types of member differences increase workload as well as frustration and conflicts. However, they facilitate situated learning, problem characterization, design review, and boundary spanning. We discuss implications for work performance and community engagement, and suggest several ways to leverage member differences in the open source software peer review process.     

Effective bias reduction methods for passive source localization using TDOA and GROA

For passive source localization based on both TDOA and GROA, this paper proposes two bias reduction methods for the well-known Weighted-Least-Squares (WLS) estimator. We first derive the passive source localization bias from the two-step algebraic closed-form solution. This bias is found to be considerably larger than the Maximum Likelihood Estimator (MLE) and limits the WLS estimator’s practical applications. In this paper, We develop two methods to reduce the bias. The first one called Bias-Subtraction-Method (BSM) directly subtracts the expected bias from the solution of the WLS estimator, and the second one called Bias-Reduction-Method (BRM) imposes a constraint to the equation error formulation to improve the source location estimate. The noise covariance matrix must be known exactly in calculating the expected bias in BSM, and we only need to know the structure of it in BRM. For far-field sources localization when the noise is Gaussian and not too large, both of the two proposed methods can reduce the localization bias effectively and achieve the Cramér-Rao Lower Bound (CRLB) performance very well, and the BRM almost has the same performance as the MLE estimator. Simulations corroborate the performance of the two proposed methods.     

The power of gifts: organizing social relationships in open source communities

Abstract. In writings on the open source software development model, it is often argued that it is successful as a result of the gift economy that embraces activities in online communities. However, the theoretical foundations for this argument are seldom discussed and empirically tested. Starting with the 'classic' theories of gift giving, we discuss how they need to be developed in order to explain gift-giving practices in digital domains. In this paper, we argue that the gift economy is important, not only because it creates openness, but also because it organizes relationships between people in a certain way. Open source software development relies on gift giving as a way of getting new ideas and prototypes out into circulation. This also implies that the giver gets power from giving away. This power is used as a way of guaranteeing the quality of the code. We relate this practice to how gifts, in the form of new scientific knowledge, are given to the research community, and how this is done through peer review processes.     

开源软件生产的网络化创新系统研究*

从系统工程、经济学和生态学的角度分析了开源软件社区的内在创新机理。首先,基于系统学理论定义了开源软件生产系统的概念;然后通过分析开源软件与私有软件生产系统的差异,归纳了开源生产行为的经济学特征;最后基于耗散结构理论和复杂科学理论提出了创新熵来度量开源社区的创新效能,并进一步揭示了开源社区网络创新的内在演化机理。