553,179 research outputs found
Autonomous Mobility and Energy Service Management in Future Smart Cities: An Overview
With the rise of transportation electrification, autonomous driving and
shared mobility in urban mobility systems, and increasing penetrations of
distributed energy resources and autonomous demand-side management techniques
in energy systems, tremendous opportunities, as well as challenges, are
emerging in the forging of a sustainable and converged urban mobility and
energy future. This paper is motivated by these disruptive transformations and
gives an overview of managing autonomous mobility and energy services in future
smart cities. First, we propose a three-layer architecture for the convergence
of future mobility and energy systems. For each layer, we give a brief overview
of the disruptive transformations that directly contribute to the rise of
autonomous mobility-on-demand (AMoD) systems. Second, we propose the concept of
autonomous flexibility-on-demand (AFoD), as an energy service platform built
directly on existing infrastructures of AMoD systems. In the vision of AFoD,
autonomous electric vehicles provide charging flexibilities as a service on
demand in energy systems. Third, we analyze and compare AMoD and AFoD, and we
identify four key decisions that, if appropriately coordinated, will create a
synergy between AMoD and AFoD. Finally, we discuss key challenges towards the
success of AMoD and AFoD in future smart cities and present some key research
directions regarding the system-wide coordination between AMoD and AFoD.Comment: 19 pages, 4 figure
HBT: A (mostly) experimental overview
I will present a review of the field of Hanbury Brown-Twiss interferometry in
relativistic heavy-ion collisions. The "HBT puzzle" is explored in detail,
emphasizing recent theoretical attempts to understand the persisting puzzle. I
also present recent experimental results on azimuthally sensitive HBT, HBT of
direct photons, and some surprises in the comparison of HBT results from p+p
and Au+Au collisions at RHIC.Comment: 8 pages, 3 figures. Proceedings of the Quark Matter 2004 conference
(Oalkland, CA, USA, January 2004
State-of-the-Art in Parallel Computing with R
R is a mature open-source programming language for statistical computing and graphics. Many areas of statistical research are experiencing rapid growth in the size of data sets. Methodological advances drive increased use of simulations. A common approach is to use parallel computing. This paper presents an overview of techniques for parallel computing with R on computer clusters, on multi-core systems, and in grid computing. It reviews sixteen different packages, comparing them on their state of development, the parallel technology used, as well as on usability, acceptance, and performance. Two packages (snow, Rmpi) stand out as particularly useful for general use on computer clusters. Packages for grid computing are still in development, with only one package currently available to the end user. For multi-core systems four different packages exist, but a number of issues pose challenges to early adopters. The paper concludes with ideas for further developments in high performance computing with R. Example code is available in the appendix
The history of WiMAX: a complete survey of the evolution in certification and standarization for IEEE 802.16 and WiMAX
Most researchers are familiar with the technical features of WiMAX technology but the evolution that WiMAX went through, in terms of standardization and certification, is missing and unknown to most people. Knowledge of this historical process would however aid to understand how WiMAX has become the widespread technology that it is today. Furthermore, it would give insight in the steps to undertake for anyone aiming at introducing a new wireless technology on a worldwide scale. Therefore, this article presents a survey on all relevant activities that took place within three important organizations: the 802.16 Working Group of the IEEE (Institute of Electrical and Electronics Engineers) for technology development and standardization, the WiMAX Forum for product certification and the ITU (International Telecommunication Union) for international recognition. An elaborated and comprehensive overview of all those activities is given, which reveals the importance of the willingness to innovate and to continuously incorporate new ideas in the IEEE standardization process and the importance of the WiMAX Forum certification label granting process to ensure interoperability. We also emphasize the steps that were taken in cooperating with the ITU to improve the international esteem of the technology. Finally, a WiMAX trend analysis is made. We showed how industry interest has fluctuated over time and quantified the evolution in WiMAX product certification and deployments. It is shown that most interest went to the 2.5 GHz and 3.5GHz frequencies, that most deployments are in geographic regions with a lot of developing countries and that the highest people coverage is achieved in Asia Pacific. This elaborated description of all standardization and certification activities, from the very start up to now, will make the reader comprehend how past and future steps are taken in the development process of new WiMAX features
Overview of event-by-event analysis of high energy nuclear collisions
The event-by-event analysis of high energy nuclear collisions aims at
revealing the richness of the underlying event structures and provide unique
measures of dynamical fluctuations associated with QGP phase transition. The
major challenge in these studies is to separate the dynamical fluctuations from
the many other sources which contribute to the measured values. We present the
fluctuations in terms of event multiplicity, mean transverse momentum, elliptic
flow, source sizes, particle ratios and net charge distributions. In addition,
we discuss the effect of long range correlations, disoriented chiral
condensates and presence of jets. A brief review of various probes used for
fluctuation studies and available experimental results are presented.Comment: Invited talk at the "XIth International Workshop on Correlation and
Fluctuation in Multiparticle Production", Nov 21-24, 2006, Hangzhou, China
(19 pages
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