Graphic-Card Cluster for Astrophysics (GraCCA) -- Performance Tests

In this paper, we describe the architecture and performance of the GraCCA system, a Graphic-Card Cluster for Astrophysics simulations. It consists of 16 nodes, with each node equipped with 2 modern graphic cards, the NVIDIA GeForce 8800 GTX. This computing cluster provides a theoretical performance of 16.2 TFLOPS. To demonstrate its performance in astrophysics computation, we have implemented a parallel direct N-body simulation program with shared time-step algorithm in this system. Our system achieves a measured performance of 7.1 TFLOPS and a parallel efficiency of 90% for simulating a globular cluster of 1024K particles. In comparing with the GRAPE-6A cluster at RIT (Rochester Institute of Technology), the GraCCA system achieves a more than twice higher measured speed and an even higher performance-per-dollar ratio. Moreover, our system can handle up to 320M particles and can serve as a general-purpose computing cluster for a wide range of astrophysics problems.Comment: Accepted for publication in New Astronom

Comments: Insider attack on Cheng et al.\u27s pairing-based tripartite key agreement protocols

Recently, Cheng et al. proposed two tripartite key agreement protocols from pairings: one is certificate-based and the other is identity-based (ID-based). In this article, we show that the two schemes are vulnerable to the insider impersonation attack and the ID-based scheme even discloses the entities¡¦ private keys. Solutions to this problem are discussed

Comments on a Provably Secure Three-Party Password-Based Authenticated Key Exchange Protocol Using Weil Pairings

In 2005, Wen et al. proposed the first provably secure three-party password-based authenticated key exchange using Weil pairings, and provided their proof in a modified Bellare-Rogaway model (BR-model). Here, we show an impersonation attack on Wen et al.¡¦s scheme and point out a main flaw of their model that allows a man-in-the-middle adversary easily violate the security

Toward a Cultural Phenomenon of Blogging--The Impacts of Individualism-Collectivism and Self-efficacy

Blogging is a form of social communication that facilitates human interaction. The cultural orientations of individualism and collectivism, which relate to basic beliefs about human relationships and interactions, should be determinants of blogging. This study explores the impacts of individualism-collectivism orientation on perceived self-efficacy in blogging, along with blogging and attitudes toward blogging. The results from an online survey of bloggers show that peoples\u27 cultural orientation of individualism-collectivism affects blogging through the mediation of perceived self-efficacy. Additionally, while self-reliance and the supremacy of individual goals increase blogging, competitiveness, solitary work preference, and the supremacy of individual interests decreases it. These results may suggest that a new cultural value is emerging among bloggers who wish to reap the benefits of the cyberworld