Investigating face‐to‐face peer interaction patterns in a collaborative Web discovery task: the benefits of a shared display

Mobile computers are now increasingly applied to facilitate face‐to‐face collaborative learning. However, the factors affecting face‐to‐face peer interactions are complex as they involve rich communication media. In particular, non‐verbal interactions are necessary to convey critical communication messages in face‐to‐face communication. Through gathering discourse and non‐verbal interaction records, this study explores the peer interactions supported by two collaborative applications: one with mobile computers and the other with shared‐display groupware (SDG). The results show that the students tended to interact with each other according to a distributed and an unsocial interaction pattern when using the application with mobile computers. In contrast, the students who learned with the SDG demonstrated a shared interaction pattern, whereby they often jointly focused on and referred to the shared work. The analysis of the students' work further found that a higher level of discussion was generally associated with the shared interaction pattern. The results seem to support SDG as being useful in augmenting face‐to‐face peer interaction supported by mobile computers. The implications derived from the findings also support the argument that non‐verbal interaction records are useful for quantitatively and qualitatively analysing face‐to‐face peer interactions.     

面向声音监测的多媒体传感器节点硬件设计与实现

多媒体传感器网络能够采集和传输信息丰富的音频、视频、图像等多媒体信息,具有十分广泛的应用前景,是近年来无线传感器网络的研究热点。目前,国外多媒体传感器节点主要针对图像传输;国内使用的节点大多都难以满足多媒体信息处理和传输等方面的应用要求。本文针对鄱阳湖鸟类声音监测的应用,设计实现了一种新型的高性能多媒体传感器节点。实验结果表明,由该节点组成的多媒体传感器网络,能有效建立路由,实时地感知和采集网络覆盖区域内的多媒体信息。     

Joint fingerprinting and encryption in hybrid domains for multimedia sharing in social networks

The advent of social networks and cloud computing has made social multimedia sharing in social networks become easier and more efficient. The lowered cost of redistribution, however, also invites much motivation for large-scale copyright infringement, so it is necessary to safeguard multimedia sharing for security and privacy. In this paper, we proposed a novel framework for joint fingerprinting and encryption (JFE) based on Cellular Automata (CA) and social network analysis (SNA) with the purpose of protecting media distribution in social networks. The motivation is to map the hierarchical community structure of social networks into the tree structure of Discrete Wavelet Transform (DWT) for fingerprinting and encryption. First, the fingerprint code is produced by using SNA. Then the obtained fingerprints are embedded into the DWT domain. Afterwards, CA is used for permutation in the DWT domain. Finally, the image is diffused with XOR operation in the spatial domain. The proposed method, to the best of our knowledge, is the first JFE method using CA and SNA in hybrid domains for security and privacy in social networks. The use of fingerprinting along with encryption can provide a double-layer protection for media sharing in social networks. Both theoretical analysis and experimental results validate the effectiveness of the proposed scheme.     

基于DirectShow的多媒体流系统设计与应用

阐述了DirectShow的基本原理,给出了基于DirectShow的应用系统开发的基本思想、基本方法.通过实例讨论了多媒体流的捕获和播放技术以及DirectShow过滤器和过滤器图管理器的构建和管理;讨论了利用Visual C 实现基于DirectShow的多媒体流系统开发的关键技术,并对多媒体系统实现的开发方法和编程过程做出说明,并给出核心代码.结果表明,在此基础上实现的多媒体应用系统,具有更好的可重用性和可扩展性,缩短了开发周期.     

一种可支持多路音频、视频同时播放的装置设计

介绍了一种可支持多路音频／视频同时播放的装置,该装置可用来实现电脑或电视等多媒体设备在播放多个视频画面的同时,获得互不干扰的音频输出。该装置中的数据缓存模块连接有多个音频／视频读取模块,音频／视频读取模块的输出端分别与音频输出接口和视频呈现模块连接。     

Feature set and architecture of a multimedia news system over an ATM network

In this paper we discuss a multimedia news system that we have developed in the Multimedia Information Research Laboratory at the University of Ottawa and beyond. We focus on the feature set—that is, the tools and facilities associated with the system. We explain the functionality of each and give some real examples of the system in action. We then outline the architecture—the system consists of a production server for document authoring, a conferencing system for collaborative news article creation, a content database for authors, a hypernews database for hypermedia news documents, a news database server with aging and archiving, and user sites. The goal was to have all components of the system communicating on OCRInet—an R&D ATM network in the Ottawa region. We then introduce the challenges of representing and browsing large video objects and to this end we introduce a novel solution that we call video-tiles. This video tool is an effective way to browse large news videos that are frequently connected with our multimedia news articles.     

Learning technologies: Affective and social issues in computer-supported collaborative learning

This paper is concerned with affective issues in learning technologies in a collaborative context. Traditionally in learning there has been a division between cognition and affect: where cognition is concerned with skills and processes such as thinking and problem-solving and affect with emotional areas such as motivation, attitudes, feelings. Affective issues have been viewed as somewhat problematic in studying learning, so although it is well known that learner attitude, motivation, and emotional state are very important, they have often been excluded from the frame of research, or studied separately from cognitive learning. This position is gradually changing and this paper considers what previous research has been conducted in these areas. It discusses the role of affective factors in three main areas of collaboration: in settings where learners are co-located, in on-line communities and to support and develop socio-emotional skills. It considers relevant developments in these areas, what the outcomes have been and suggests important directions for future research.     

Efficient model checking of properties of a distributed application: a multimedia case study

A system supporting video on demand is modeled in the process calculus CCS (Calculus of Communicating Systems), while some properties are expressed in a temporal logic and verified by means of the model checkers of the North Carolina Concurrency Workbench. This application was chosen as a case study to evaluate the usefulness of a methodology, by means of which a property is checked on reduced models obtained issuing abstractions of the system on the basis of the formula. Experimental results are shown and discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

Design and implementation of a multimedia CSCW platform

In this paper, a generic four-layer framework for computer supported cooperative work (CSCW) is proposed. With clear separation of functionalities in each layer of the framework, application developers could implement their specific CSCW applications easily. Based on the four-layer framework, the architecture of a general purpose CSCW platform is designed and implemented with the necessary functionalities to help the collaborations among group members. To provide the system with more features and user friendliness, multimedia processing and transmission capabilities for audio and video are incorporated into the platform. Features like application-sharing, group decision support, multimedia mail transmission, etc., are well implemented in the platform. Moreover, an efficient network transport protocol, called VXTP, is designed and implemented to avoid the transmission overhead of conventional TCP. The performance measurements using both VXTP and TCP are given in the paper for comparison. Lastly, compared with other CSCW systems, our design achieves greater flexibility and portability by adopting the generality philosophy in the framework.     

Indexing and Retrieval of Audio: A Survey

With more and more audio being captured and stored, there is a growing need for automatic audio indexing and retrieval techniques that can retrieve relevant audio pieces quickly on demand. This paper provides a comprehensive survey of audio indexing and retrieval techniques. We first describe main audio characteristics and features and discuss techniques for classifying audio into speech and music based on these features. Indexing and retrieval of speech and music is then described separately. Finally, significance of audio in multimedia indexing and retrieval is discussed.     

Design and Implementation of a Java-based Meeting Space over Internet

This paper describes the implementation of Java Meeting Space (JMS), a generic, extensible framework and environment for developing synchronous collaborative applications. The JMS framework is based on a fully object-oriented replicated architecture where the application instances and management services are all replicated at each site. JMS provides basic CSCW coordination services: session management and dynamic floor control services. As a framework, it provides a set of programming interfaces that allow an application developer to take advantage of coordination services in the runtime environment.     

DirectShow技术的应用研究与开发

研究了采用DirectShow技术从音视频设备获取媒体数据并进行后期处理的问题. 随着多媒体技术应用的越来越广, 用户对多媒体产品的要求也越来越高. 早期的多媒体软件与音视频设备高度关联, 存在着通用性差、功能扩展难等诸多局限, 不能满足用户需求. 本文基于DirectShow系统对硬件的充分支持以及硬件设备无关性的特点, 提出了一种采用DirectShow技术的设计方法, 解决了多媒体软件受限于设备的问题. 经测试表明, 该方法达到了预期, 在多媒体领域将有良好的应用前景.     

When groups decide to use asynchronous online discussions: collaborative learning and social presence under a voluntary participation structure

The purpose of this study is to explore how groups decide to use asynchronous online discussion forums in a non-mandatory setting, and, after the group decision is made, how group members use online discussion forums to complete a collaborative learning project requiring complex data gathering and research processes. While a large body of research on computer-mediated communication (CMC) has documented successful intervention strategies to promote and sustain online discussion forums, little of the research has examined the use of online discussion forums in voluntarily contexts, wherein the decision to use online discussion forums is a personal decision and participation is not a graded component. This study approaches the research questions using a naturalistic case study of one graduate-level blended learning course with 55 students. Employing both student interviews and content analysis methods, this study revealed that the factors affecting the group decision to use online discussion forums are (1) successful or unsuccessful experiences during the first trial, (2) perceived affordances of CMC tools, and (3) the interplay between the nature of collaborative tasks and perceived efficiency. The content analysis of online postings in two voluntary groups revealed that when groups decided to use online discussion forums, participation levels were almost equal among individual group members, and discussion threads were sustained until the final completion of the collaborative project.     

Implementation of AVS Jizhun decoder with HW/SW partitioning on a coarse-grained reconfigurable multimedia system

In this paper,a TPP(Task-based Parallelization and Pipelining)scheme is proposed to implement AVS(Audio Video coding Standard)video decoding algorithm on REMUS(REconfigurable MUltimedia System),which is a coarse-grained reconfigurable multimedia system.An AVS decoder has been implemented with the consideration of HW/SW optimized partitioning.Several parallel techniques,such as MB(Macro-Block)-based parallel and block-based parallel techniques,and several pipeline techniques,such as MB level pipeline and block level pipeline techniques are adopted by hardware implementation,for performance improvement of the AVS decoder.Also,most computation-intensive tasks in AVS video standards,such as MC(Motion Compensation),IP(Intra Prediction),IDCT(Inverse Discrete Cosine Transform),REC(REConstruct)and DF(Deblocking Filter),are performed in the two RPUs(Reconfigurable Processing Units),which are the major computing engines of REMUS.Owing to the proposed scheme,the decoder introduced here can support AVS JP(Jizhun Profile)1920×1088@39fps streams when exploiting a 200 MHz working frequency.     

Using multimedia to teach inservice teachers: Impacts on learning, application, and retention

This study investigated teachers’ ability to learn, apply in lesson plans, and retain knowledge of classroom discourse from a single module of a multimedia professional development program, used with 39 K-12 teachers enrolled in two graduate courses. Data collection and analysis included: (a) teacher development of – and panel review of – lesson plans integrating discourse, and (b) follow-up teacher interviews one year later. The study found: (a) the video modeling in the module was effective in helping teachers learn, and (b) discourse strategies were learned, applied, and retained. Implications for professional development with multimedia to teach classroom discourse include: (a) recursive use, (b) reflection, (c) multiple examples, (d) counter examples, and (e) prompts for observation.     

Modulus consensus in a network of singularly perturbed systems with collaborative and antagonistic interactions

This paper addresses the modulus consensus in a network of singularly perturbed systems, all of which own multi-time scales characteristics. The interactions among the agents are collaborative and antagonistic interactions, and it can been modelled by a signed directed graph. Also, the effect of time-varying delay has been taken into account when modelling the agent dynamics. Based on singularly perturbed decomposition method, Kronecker product technique and the comparison principle, several sufficient conditions are presented under which networked singularly perturbed time-varying delay systems with collaborative and antagonistic interactions achieve modulus consensus. Moreover, the upper bound of singular perturbation parameter is deduced explicitly. Two simulation examples are presented to illustrate the validity of the proposed results.     

基于AT89C2051的单户可视对讲门铃室内分机的设计

本文介绍一种基于单片机AT89C2501的单户可视对讲门铃室内分机的工作原理及软、硬件的设计与实现方法。     

Lossless data transmission for Internet of things application over wireless multimedia sensor networks using enhanced and optimal path scheduling approach to maximizing the quality of service

The congestion of packet forwarding between a source and destination is challenging on downlink transmission in the entire file (ex. Audio and Video). Whenever file is been uploaded to the server, a user requests for file where server transmits it without knowledge of user's bandwidth, which is a major, cause of packet loss or time duration in the receiver end. To accumulate the better solution, Enhanced and Optimal Path Scheduling Approach (EOPSA) designs to find optimal path scheduling for multimedia data transmission in multimedia sensor network over cloud server using IoT devices. EOPSA studied the multisource video-on-demand streaming in multimedia sensor networks. The method introduced a heuristic distributed protocol to find optimal route for multimedia data transmissions. Efficient way to identify the bandwidth before the transmission ensures link establishment between sender and receiver. Here, the capture of bandwidth helps to check user's system capability to forward requested media data. Based on experiment evaluation, EOPSA improves 0.20 packet delivery ratio, 130 throughput, 0.20 second average delay and 14 communication overhead for 15, 25, 50, 75, and 100 nodes compared than conventional methods.     

A new tool for processing atmospheric emission inventories: Technical aspects and application to the ESCOMPTE study area

Emission databases need to be processed for several purposes, e.g., policy and scientific, and so require flexible and fast handling. As a result, the creation and use of convenient interactive tools allowing easy and fast processing are of high importance. In this paper, a new software devoted to emission inventories processing is presented and applied to the actualization of the ESCOMPTE inventory. The ESCOMPTE inventory is a yearly (1999) high-resolution (1 km²) emission inventory created for use in chemical transport models to study ozone pollution. This tool includes several functions allowing the update of emission inventories at different temporal and spatial resolutions based on the reference ESCOMPTE inventory. The actualized yearly and hourly inventories are found consistent with the hypothesis involved in emission inventory creation. Due to its flexible architecture, several other applications related to air quality analysis can be performed such as the creation of emission scenarios allowing the evaluation of abatement strategies and regulation effects on anthropogenic emissions. Also, the architecture of the software allows an easy application to other emission inventories provided that they have similar or adaptable structure compared to the ESCOMPTE one.     

“It's Just a Matter of Common Sense”: Ethnography as Invisible Work

Anthropologists have been using ethnographic methods since the 1970s to support the design and evaluation of software. While early use of such skills in the design world was viewed as experimental, at least by computer scientists and engineers, ethnography has now become established as a useful skill in technology design. Not only are corporations and research laboratories employing anthropologists to take part in the development process, but growing numbers of non-anthropologists are attempting to borrow ethnographic techniques. The results of this appropriation have brought out into the open a kind of paradox: while ethnography looks and sounds straightforward, this is not really the case. The work of untrained ethnographers tends to overlook things that anthropologists see as important parts of the research process. The consistency of this pattern suggests that some aspects of ethnographic fieldwork are invisible to the untrained eye. In short, ethnography would appear to constitute an example of invisible work. Drawing on my own decade of experience as an anthropologist working in design, I attempt to clarify the nature of ethnographic expertise, describe six misconceptions about ethnography that I have encountered among scientists, and present real-life examples to illustrate why quasi-ethnographic work based on these misconceptions is likely to be superficial and unreliable.