Tun Lu

Interest-based real-time content recommendation in online social communities

The fast-growing popularity of online social communities and the massive amounts of user-generated content pose a critical need for, and new challenges on, content recommender system. The system needs to identify the unique and diverse interests of individual users and deliver content to interested users on a real-time basis. In this work, we propose Farseer, a system for personalized real-time content recommendation and delivery in online social communities. The proposed solution consists of a set of integrated offline and online algorithms that identify and utilize unique item-based interest clusters and cluster-based item rating in order to recommend newly-generated content items to individual users in real time. Our main contributions are (1) a detailed analysis of content popularity distribution and user interest distribution in online social communities; (2) a novel interest-based clustering and cluster-based content recommendation solution; and (3) a complete implementation and deployment in an online social community. Evaluation results gathered from real-world user studies demonstrate that the proposed system outperforms three widely-used collaborative filtering algorithms (kNN, PLSA, SVD) in existing recommender systems. It can effectively identify personal interests and improve the quality and efficiency of real-time personalized content recommendation in online social communities.

An operational transformation based synchronization protocol for web 2.0 applications

Current Web 2.0 services are making mass collaboration a reality. Using a Web browser, people can participate in cooperative work anytime, anywhere from any computing device as long as there is an Internet connection. Lying in the heart of some well-known services is an optimistic consistency control technique called operational transformation (OT). This paper proposes TIPS, a novel sync protocol that adapts OT for Web 2.0 applications. Based on a recent theoretical framework called ABT, it ensures not only convergence but also the right object order for linear documents. Designed to address the HTTP style of communication, TIPS allows clients to sync with the server by independent time intervals and dynamically join and leave at any time. When processing do operations, its time complexity is linear in the total number of operations generated by all clients during one server interval and independent of the size of history. TIPS is efficient for supporting a spectrum of (near-)realtime to asynchronous collaboration editing tasks.

Reliving the Past & Making a Harmonious Society Today: A Study of Elderly Electronic Hackers in China

This paper tells a story of DIY (do it yourself) making that does not neatly fit more familiar narratives of making: as individual empowerment, as a democratizing force, and as technoscientific innovation. Drawing on ethnographic research with a collective of elderly electronic hackers in China, we provide insights into the socio-technical and politico-economic processes of hacking and making. This paper examines how the activity of making functioned for elderly DIY enthusiasts as way of remaking and reliving the past and as a means for expressing class belonging and citizenship. We show that making and hacking is not practiced in a void independent of social, political or economic forces. Rather, making unfolds in relation to, and is contingent on, societal norms and specific techno-cultural histories. As much as hacking empowers certain people, it excludes others and functions as a site for the exercise of power and social distinction making.

Meanings and boundaries of scientific software sharing

In theory, software, like other digital artifacts, can be freely copied and distributed. In practice, however, its effective flow is conditioned on various technical and social factors. In this paper, drawing on ethnographic work primarily with a bio-informatics research team in China, we report on meanings of scientific software sharing as embedded in social practices of learning, apprenticeship, membership, publication, and reputation. We illustrate that while free flow is important, boundary management is equally important for the effective travel of software to its appropriate destinations. Our study highlights a number of issues that are important to consider for effectively supporting sharing and collaboration in science.

Being senior and ICT: a study of seniors using ICT in China

System design for seniors often focuses on the decline of their biological capabilities and social connectedness. This approach has been challenged as too simplistic to capture what it really means to be senior. This paper presents a qualitative study of 17 seniors in urban China (age ranging from 50s to 70s), who have adopted and incorporated ICT into their daily lives. Findings from this study show that the ways in which seniors attend to ICT are not simply shaped by changes in health or other wellbeing, but also by their life attitudes, value systems, relationships to younger generations as well as historical specifics during their coming of age. This paper contributes by showing that 1) what it means to be senior is shaped from within a whole social ecology of past and current experiences, values and interactions; 2) senior identities are not fixed, but continuously negotiated, articulated and enacted through ICT; 3) social interaction and access of technologies are highly intertwined.

CLAF: Solving intention violation of step-wise operations in CAD groupware

Operations in CoAutoCAD systems are either single-step or step-wise. Single-step operations (such as Line, Box, etc.) are completed in one step, while step-wise operations (such as Mirror, Array, etc.) take several continuous or discrete steps and in some scenarios (such as Copy-Paste), and the number of steps may not be known beforehand. Therefore, during the execution process, the intention of step-wise operations may be violated by concurrent operations coming from remote sites. This paper investigates the problem of intention violation and proposes to maintain the semantic intention of operations by introducing a novel approach called CLAF (Check Last Avoid Future) to solve previous violations while avoiding future violations using newly-updated document status. To infer the execution formats of causally-ready operations, VT transformation function is introduced to extend the GOTO algorithm so as to reflect the influence of one operation on another. An integrated example analysis is provided to demonstrate the effectiveness of our strategy.

Semantic classification and query of engineering drawings in the shipbuilding industry

Manufacturing enterprises require an efficient method to manage their engineering drawings. This paper proposes to use ontology to eliminate confusion of semantic concepts in the shipbuilding industry. The proposed management method of engineering drawings is to establish classification trees according to different kinds of classifications in the shipbuilding industry. It also defines the correlation of ship instances, which can facilitate the search process. Moreover, this paper introduces a new algorithm for querying ship instances in conditional sets. The proposed method has been applied in a ship design knowledge management system for sharing and searching ship design data.

A partial replication approach for anywhere anytime mobile commenting

Commenting systems play increasingly important roles in the interactive web applications. Meanwhile, more and more web applications are visited on mobile devices. However, the intermittent connection of mobile networks and resource limitation of mobile devices pose great challenges, mainly in terms of interactive responsiveness and data consistency. In this paper, we present the first work of partial replication solution based on collaborative editing techniques, which can address the issues of local responsiveness and resource limitation on mobile commenting systems. We report how we address the consistency maintenance challenges that come with the partial replication approach. With this approach, users are allowed to smoothly comment anywhere anytime. The comment thread can be incrementally updated and automatically synchronized with strong data consistency guarantees. We implemented a system prototype called Hydra and evaluated it on a real data set.

Maintaining time and space consistencies in hybrid CAD environments: Framework and algorithms

Based on the analysis of two types of collaborations during engineering design, namely time collaboration and space collaboration, this paper introduces a Total Data Model (TDM) centered framework to support the maintenance of time and space consistencies in hybrid CAD environments. By separating data and view, the proposed framework supports view-wandering between different perspectives so that designers can adjust their behaviors to avoid conflicts. The maintenance of time consistency is achieved by utilizing the Address Space Transformation (AST) algorithm. In order to adapt AST to new large-scale design environments, an effective garbage collection strategy is proposed. As for space collaboration, a conflict detection algorithm based on feature face is introduced. A prototype system has been developed to prove the validity, efficiency, and feasibility of the proposed framework.

The collective infrastructural work of electricity: exploring feedback in a prepaid university dorm in China

Feedback on resource consumption is often explored as a way to raise awareness and saving resources. This paper reports findings from a user study of a feedback system deployed in a Chinese university dormitory with a prepaid electricity system, a context different from the more common domestic setting in the West explored in prior research. With this work, we move beyond resource conservation and draw attention to an often-neglected aspect of infrastructural work -- the work to ensure the smooth and continuous supply of resources from end users. This paper examines the ways in which people attend to electricity through what we term collective infrastructural work, i.e. people perceive electricity as a marginal concern, and yet invest time to maintain it collectively. We draw out a number of implications for design and evaluation from this work.