University of North Carolina at Charlotte

About: University of North Carolina at Charlotte is a education organization based out in Charlotte, North Carolina, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 8772 authors who have published 22239 publications receiving 562529 citations. The organization is also known as: UNC Charlotte & UNCC.

Ownership structure and innovation: An emerging market perspective

Abstract: Considerable attention has been focused on the ways in which emerging market firms can obtain and mobilize the knowledge and resources required for innovation. Innovation is a particular challenge in emerging markets because of inadequate external institutions. In this study, we focus on the importance of ownership structure, and in particular on ownership type diversity and ownership concentration. Using transaction cost and agency theories embedded in an emerging market context, we argue that ownership structure provides an important mechanism by which firms can assemble and direct the resources necessary for innovation in the context of inadequate external institutions. Specifically, we hypothesize that ownership type diversity improves innovation performance and that increasing ownership concentration has the same effect, but only up to a point. Using a panel dataset of 487 and 475 Chinese listed companies during 2004–2005 and 2005–2006 respectively, we find supportive empirical evidence for our hypotheses. Our findings also suggest that ownership type diversity is a more important factor in explaining innovation performance than ownership concentration, although most of the extant literature focuses on the latter.

Defining Insight for Visual Analytics

Abstract: Many have argued that providing insight is the main goal of information visualization. Stuart Card, Jock Mackinlay, and Ben Shneiderman declare that "the purpose of visualization is insight, while Jim Thomas and Kris Cook propose in Illuminating the Path that the purpose of visual analytics is to enable and discover insight. The idea that visualization should lead to insight seems logical, but researchers in the community have been slow to build on the concept because insight is difficult to define. As Ji Soo Yi and his colleagues point out, although a few definitions of insight exist, no commonly accepted definition has emerged in the community.

ProSpect: A Proactive Spectrum Handoff Framework for Cognitive Radio Ad Hoc Networks without Common Control Channel

Abstract: Cognitive Radio (CR) technology is a promising solution to enhance the spectrum utilization by enabling unlicensed users to exploit the spectrum in an opportunistic manner. Since unlicensed users are temporary visitors to the licensed spectrum, they are required to vacate the spectrum when a licensed user reclaims it. Due to the randomness of the appearance of licensed users, disruptions to both licensed and unlicensed communications are often difficult to prevent, which may lead to low throughput of both licensed and unlicensed communications. In this paper, a proactive spectrum handoff framework for CR ad hoc networks, ProSpect, is proposed to address these concerns. In the proposed framework, Channel-Switching (CW) policies and a proactive spectrum handoff protocol are proposed to let unlicensed users vacate a channel before a licensed user utilizes it to avoid unwanted interference. Network coordination schemes for unlicensed users are also incorporated into the spectrum handoff protocol design. Moreover, a distributed channel selection scheme to eliminate collisions among unlicensed users in a multiuser spectrum handoff scenario is proposed. In our proposed framework, unlicensed users coordinate with each other without using a Common Control Channel (CCC), which is highly adaptable in a spectrum-varying environment. We compare our proposed proactive spectrum handoff protocol with a reactive spectrum handoff protocol, under which unlicensed users switch channels after collisions with licensed transmissions occur. Simulation results show that our proactive spectrum handoff outperforms the reactive spectrum handoff approach in terms of higher throughput and fewer collisions to licensed users. Furthermore, our distributed channel selection can achieve higher packet delivery rate in a multiuser spectrum handoff scenario, compared with existing channel selection schemes.

Incentive Mechanisms for Participatory Sensing: Survey and Research Challenges

Abstract: Participatory sensing is a powerful paradigm that takes advantage of smartphones to collect and analyze data beyond the scale of what was previously possible. Given that participatory sensing systems rely completely on the users’ willingness to submit up-to-date and accurate information, it is paramount to effectively incentivize users’ active and reliable participation. In this article, we survey existing literature on incentive mechanisms for participatory sensing systems. In particular, we present a taxonomy of existing incentive mechanisms for participatory sensing systems, which are subsequently discussed in depth by comparing and contrasting different approaches. Finally, we discuss an agenda of open research challenges in incentivizing users in participatory sensing.

Strong Strain Hardening in Nanocrystalline Nickel

Abstract: Low strain hardening has hitherto been considered an intrinsic behavior for most nanocrystalline (NC) metals, due to their perceived inability to accumulate dislocations. In this Letter, we show strong strain hardening in NC nickel with a grain size of approximately 20 nm under large plastic strains. Contrary to common belief, we have observed significant dislocation accumulation in the grain interior. This is enabled primarily by Lomer-Cottrell locks, which pin the lock-forming dislocations and obstruct dislocation motion. These observations may help with developing strong and ductile NC metals and alloys.