18533540
Beyond Instant Messaging
The recent rise in popularity of IM (instant messaging) has driven the developmentof platforms and the emergence of standards to support IM. Especially as theuse of IM has migrated from online socializing at home to business settings,there is a need to provide robust platforms with the interfaces that businesscustomers use to integrate with other work applications. Yet, in the rush todevelop a mature IM infrastructure, it is also important to recognize that IMfeatures and uses are still evolving. For example, popular press stories1 haveraised the concern that IM interactions may be too distracting in the workplace.This concern suggests that we still need to fine-tune the interface design forIM so the benefits of quick, lightweight communication can be gained withoutcreating a distracting burden for users. How can the industry meet the demandfor robust platforms and standards for IM without locking out innovation anddevelopment?
6543572
Findings from Observational Studies of Collaborative Work
Abstract The work activity of small groups of three to four people was videotaped and analysed in order to understand collaborative work and to guide the development of tools to support it. The analysis focused on the group's shared drawing activity—their listing, drawing, gesturing and talking around a shared drawing surface. This analysis identified specific features of collaborative work activity that raise design implications for collaborative technology: (1) collaborators use hand gestures to uniquely communicate significant information; (2) the process of creating and using drawings conveys much information not contained in the resulting drawings; (3) the drawing space is an important resource for the group in mediating their collaboration; (4) there is a fluent mix of activity in the drawing space; and (5) the spatial orientation among the collaborators and the drawing space has a role in structuring their activity. These observations are illustrated with examples from the video data, and the design implications they raise are discussed.
43821577
When Can I Expect an Email Response? A Study of Rhythms in Email Usage
A study of email responsiveness was conducted to understand how the timing of email responses conveys important information. Interviews and observations explored users' perceptions of how they responded to email and formed expectations of others' responses to them. We identified ways in which users maintain and cultivate a responsiveness image for projecting expectations about their email response. We also discuss other contextual cues people use to discover email responsiveness, which include using other tools such as the calendar and phone, accounting for the amount of work time overlap available, and establishing a pacing between email correspondents. These cues help users develop a sense of when to expect a response and when breakdown has occurred, requiring further action.
1186186
Piazza: a desktop environment supporting impromptu and planned interactions
Much of the support for communication across distributed communities has focused on meetings and intentional contact. However, most interactions within co-located groups occur when people happen to run into each other. Such unintended interactions should also be supported among distributed communities. We conducted a study of the communication patterns of a large, distributed organization and found that people tend to disseminate information using formal techniques, even though people usually receive information informally. We then designed a system called Piazza that is intended to support the range of communication styles evident in large communities, paying particular attention to adchessing the problems revealed in our study. Piazza allows people to be aware of others who are doing similar tasks when they are using their computers, the~by enabling unintended interactions. It also supports intentiomd contacts and planned meetings. We discuss issues for analysis in an upcoming use study.
206793142
What video can and cannot do for collaboration: A case study
As multimedia become an integral part of collaborative systems, we must understand how to design such systems to support the user's rich set of existing interaction skills, rather than requiring people to adapt to arbitrary constraints of technology-driven designs. To understand how we can make effective use of video in remote collaboration, we compared a small team's interactions through a desktop video conferencing prototype with face-to-face interactions and phone conversations. We found that, compared with audio-only, the video channel of our desktop video conferencing prototype adds or improves the ability to show understanding, forecast responses, give nonverbal information, enhance verbal descriptions, manage pauses, and express attitudes. These findings suggest that video may be better than the phone for handling conflict and other interaction-intense activities. However, the advantages of video depend critically on the nearly-instantaneous transmission of audio, even if it means getting out of sync with the video image. Nonetheless, when compared with face-to-face interaction, it can be difficult in video interactions to notice peripheral cues, control the floor, have side conversations, point to things or manipulate real-world objects. To enable rich interactions fully, video should be integrated with other distributed tools that increase the extent and type of shared space in a way that enables natural collaborative behaviors within those environments.
10355154
Supporting distributed groups with a Montage of lightweight interactions
The Montage prototype provides lightweight audio-video glances among distributed collaborators and integrates other applications for coordinating future contact. We studied a distributed group across three conditions: before installing Montage, with Montage, and after removing Montage. We collected quantitative measures of usage as well as video-tape and user perception data. We found that the group used Montage glances for short, lightweight interactions that were like face-to-face conversations in many respects. Yet like the phone, Montage offered convenient access to other people without leaving the office. Most glances revealed that the person was not available, so it was important to integrate other tools for coordinating future interaction. Montage did not appear to displace the use of e-mail, voice-mail, or scheduled meetings.
207188648
Reliable Ad Hoc Routing Based on Mobility Prediction
Reliability is a very important issue in Mobile Ad hoc NETworks (MANETs). Shortest paths are usually used to route packets in MANETs. However, a shortest path may fail quickly, because some of the wireless links along a shortest path may be broken shortly after the path is established due to mobility of mobile nodes. Rediscovering routes may result in substantial data loss and message exchange overhead. In this paper, we study reliable ad hoc routing in the urban environment. Specifically, we formulate and study two optimization problems. In the minimum Cost Duration-bounded Path (CDP) routing problem, we seek a minimum cost source to destination path with duration no less than a given threshold. In the maximum Duration Cost-bounded Path (DCP) routing problem, we seek a maximum duration source to destination path with cost no greater than a given threshold. We use a waypoint graph to model the working area of a MANET and present an offline algorithm to compute a duration prediction table for the given waypoint graph. An entry in the duration prediction table contains the guaranteed worst-case duration of the corresponding wireless link. We then present an efficient algorithm which computes a minimum cost duration-bounded path, using the information provided in the duration prediction table. We also present a heuristic algorithm for the DCP routing problem. In addition, we show that the proposed prediction and routing schemes can be easily applied for designing reliable ad hoc routing protocols. Simulation results show that our mobility prediction based routing algorithms lead to higher network throughput and longer average path duration, compared with the shortest path routing.
39775533
Research of Atomic and Anonymous Electronic Commerce Protocol
Atomicity and anonymity are the two important requirements for application in electronic commerce. However absolutely anonymity may lead to confliction with law enforcement, e.g. blackmailing or money laundering. Therefore, it is important to design systems satisfying both atomicity and revocable anonymity. Based on the concept of two-phase commitment, we realize atomicity in electronic transaction with the Trusted Third Part as coordinator. Also we develops Brands' fair signature model, propose a method to enable not only anonymity but also owner-trace and money-trace.
15896075
Effective bandwidth-based QoS provisioning for real-time audio/video streaming over MIMO-OFDM wireless networks
We propose a cross-layer design scheme to support the real-time quality of service (QoS) guarantees for heterogeneous mobile users over downlink MIMO-OFDM wireless networks. Inspired by the effective bandwidth theory originally established for wired networks, we develop the approach to apply the theory into wireless networks. Based on MIMO-OFDM infrastructure employed at the physical (PHY)-layer, we analytically derive the medium access control (MAC)-layer admission-control and time-slot allocation algorithms to guarantee the statistical delay-bound for different real-time users. Simulation results show that the proposed scheme can efficiently support the wireless QoS requirement for diverse real-time mobile users.
46008282
A Head Gesture Recognition Algorithm
In this paper, we present a head gesture recognition algorithm that is based on the tracking technique developed by Kanade, Luca, and Tomasi (KaLuTo) and a one-class-in-one neural network algorithm. In our method, human skin colors are used to detect the head from complex backgrounds and the KaLuTo algorithm is applied to detect and track feature points on the head. Feature points tracked in successive frames are used to construct a feature vector as the input to the one-class-in-one neural network, which is employed to classify the head gestures into different classes. This method can offer some robustness to different background conditions. Experimental results prove the effectiveness of this method.
27349578
On multilevel voting
SummaryIn a distributed system mutual exclusion is often used to maintain consistency when restricted operations are performed. Mechanisms guaranteeing mutual exclusions should be both resilient and efficient. Resiliency implies high resource availability in the face of failures, while efficiency implies low overhead incurred by performing restricted operations. In this paper, we propose and study a general paradigm, called multilevel voting, which provides a general framework to assist in the design of resilient and efficient mutual exclusion mechanisms. The proposed method uses multiple level quorum consensus. Unlike another method based on the use of multiple quorum consensus, the proposed model only contains one type of integrity constraints. This has the benefit of being conceptually simple and easy to reason about. The strong resemblance with the traditional quorum consensus makes it easy for the proposed paradigm to embed any technique based on traditional quorum schemes. We show that the proposed model represents the exact class of coteries. This means that not only does it have all the power of coteries, but also all schemes under the model are correct. Thus, should the need arise, we can interchange two schemes freely without using any extra mechanisms to ensure correctness. We study a number of issues that have impact on performance such as the degree of a multilevel scheme and the order of a coterie. We explain how the model can be extended also to model the schemes for the synchronization of read and write of replicated data. We provide algorithms for the design of multilevel schemes in the context of mutual exclusion and that of read and write of replicated data.