Providing Long-Term Participation Incentive in Participatory Sensing

Providing an adequate long-term participation incentive is important for a participatory sensing system to maintain enough number of active users (sensors), so as to collect a sufficient number of data samples and support a desired level of service quality. In this work, we consider the sensor selection problem in a general time-dependent and location-aware participatory sensing system, taking the long-term user participation incentive into explicit consideration. We study the problem systematically under different information scenarios, regarding both future information and current information (realization). In particular, we propose a Lyapunov-based VCG auction policy for the on-line sensor selection, which converges asymptotically to the optimal off-line benchmark performance, even with no future information and under (current) information asymmetry. Extensive numerical results show that our proposed policy outperforms the state-of-art policies in the literature, in terms of both user participation (e.g., reducing the user dropping probability by 25% to 90%) and social performance (e.g., increasing the social welfare by 15% to 80%).Comment: This manuscript serves as the online technical report of the article published in IEEE International Conference on Computer Communications (INFOCOM), 201

A M\"untz-Collocation spectral method for weakly singular volterra integral equations

In this paper we propose and analyze a fractional Jacobi-collocation spectral method for the second kind Volterra integral equations (VIEs) with weakly singular kernel $(x-s)^{-\mu},0<\mu<1$. First we develop a family of fractional Jacobi polynomials, along with basic approximation results for some weighted projection and interpolation operators defined in suitable weighted Sobolev spaces. Then we construct an efficient fractional Jacobi-collocation spectral method for the VIEs using the zeros of the new developed fractional Jacobi polynomial. A detailed convergence analysis is carried out to derive error estimates of the numerical solution in both $L^{\infty}$- and weighted $L^{2}$-norms. The main novelty of the paper is that the proposed method is highly efficient for typical solutions that VIEs usually possess. Precisely, it is proved that the exponential convergence rate can be achieved for solutions which are smooth after the variable change $x\rightarrow x^{1/\lambda}$ for a suitable real number $\lambda$. Finally a series of numerical examples are presented to demonstrate the efficiency of the method

Studying the service encounter: Addressing the passive user experience in design

The computer system is playing an increasingly important role in the face-to-face service encounter with the rapid development of technology and strong growth in services. The design focus of Human-computer interaction is traditionally the user who primarily interacts with the interface of the computer system, but the other users who also get affected by the system are not often addressed in research. This scenario typically occurs in the face-to-face service encounter that includes a computer system, where the customer, as the passive user of the system, relies on frontline employee`s interaction with the system to get information. Essentially, the passive user experience is a part of the overall customer experience, which focuses on the moment of the service encounter. Therefore, understanding the passive user and involving the passive user experience into design practice can lead to more appealing customer experience. The main objectives of this thesis are to clarify the aspects that influence the passive user experience in Helsinki Central Library Oodi and to give corresponding proposals for designing an appealing passive user experience. The literature review explicates several notions of service and the definition of the passive user. Based on that, the research is conducted with human-centered methods consisting of mapping the passive user journey, the passive user UX curve, and the semi- structured interview. The reasons behind the dynamic trends of the UX curves and pain points of the passive user are further summarized by data analysis. The study finds the service outcome, system feedback and transparency, waiting, encouragement, customer characteristics, graphical user interface, and physical layout of products are the aspects that influence the passive user experience. Besides, the recommendations of methodology to study the passive user are provided for later research. The findings from the study delineated the characteristics of the passive user experience, and the proposals enable service suppliers to improve their service encounters from a new perspective

LHC limits on axion-like particles from heavy-ion collisions

In these proceedings we use recent LHC heavy-ion data to set a limit on axion-like particles coupling to electromagnetism with mass in the range 10-100 GeV. We recast ATLAS data as per the strategy proposed in 1607.06083, and find results in-line with the projections given there.Comment: 4 pages, 3 figures, conference proceeding for PHOTON201