arXiv subjects

Pan Hui

Publications and source records attributed to Pan Hui.

202 records · Page 12Linked to original sources

arXiv2011

On the Economics of Cloud Markets

Cloud computing is a paradigm that has the potential to transform and revolutionalize the next generation IT industry by making software available to end-users as a service. A cloud, also commonly known as a cloud network, typically comprises of hardware (network of servers) and a collection of softwares that is made available to end-users in a pay-as-you-go manner. Multiple public cloud providers (ex., Amazon) co-existing in a cloud computing market provide similar services (software as a service) to its clients, both in terms of the nature of an application, as well as in quality of service (QoS) provision. The decision of whether a cloud hosts (or finds it profitable to host) a service in the long-term would depend jointly on the price it sets, the QoS guarantees it provides to its customers, and the satisfaction of the advertised guarantees. In this paper, we devise and analyze three inter-organizational economic models relevant to cloud networks. We formulate our problems as non co-operative price and QoS games between multiple cloud providers existing in a cloud market. We prove that a unique pure strategy Nash equilibrium (NE) exists in two of the three models. Our analysis paves the path for each cloud provider to 1) know what prices and QoS level to set for end-users of a given service type, such that the provider could exist in the cloud market, and 2) practically and dynamically provision appropriate capacity for satisfying advertised QoS guarantees.

cs.NI↗

arXiv2009

Planet-scale Human Mobility Measurement

Research into, and design and construction of mobile systems and algorithms requires access to large-scale mobility data. Unfortunately, the wireless and mobile research community lacks such data. For instance, the largest available human contact traces contain only 100 nodes with very sparse connectivity, limited by experimental logistics. In this paper we pose a challenge to the community: how can we collect mobility data from billions of human participants? We re-assert the importance of large-scale datasets in communication network design, and claim that this could impact fundamental studies in other academic disciplines. In effect, we argue that planet-scale mobility measurements can help to save the world. For example, through understanding large-scale human mobility, we can track and model and contain the spread of epidemics of various kinds.

cs.NI↗

arXiv2009

Towards real-time community detection in large networks

The recent boom of large-scale Online Social Networks (OSNs) both enables and necessitates the use of parallelisable and scalable computational techniques for their analysis. We examine the problem of real-time community detection and a recently proposed linear time - O(m) on a network with m edges - label propagation or "epidemic" community detection algorithm. We identify characteristics and drawbacks of the algorithm and extend it by incorporating different heuristics to facilitate reliable and multifunctional real-time community detection. With limited computational resources, we employ the algorithm on OSN data with 1 million nodes and about 58 million directed edges. Experiments and benchmarks reveal that the extended algorithm is not only faster but its community detection accuracy is compared favourably over popular modularity-gain optimization algorithms known to suffer from their resolution limits.

physics.soc-ph↗

arXiv2000

Wess-Zumino-Berry phase interference in spin tunneling at excited levels with a magnetic field

Macroscopic quantum coherence and spin-phase interference are studied between excited levels in single-domain ferromagnetic particles in a magnetic field along the hard anisotropy axis. The system has the general structure of magnetocrystalline anisotropy, such as biaxial, trigonal, tetragonal, and hexagonal symmetry. This study not only just yields the previous spin-phase interference results for the ground state tunneling, but also provide a generalization of the Kramers degeneracy to coherently spin tunneling at low-lying excited states. These analytical results are found to be in good agreement with the numerical diagonalization. We also discuss the transition from quantum to classical behavior and the possible relevance to experiment.

cond-mat.mes-hall↗