A Collaborative Framework for In-network Video Caching in Mobile Networks

Due to explosive growth of online video content in mobile wireless networks, in-network caching is becoming increasingly important to improve the end-user experience and reduce the Internet access cost for mobile network operators. However, caching is a difficult problem due to the very large number of online videos and video requests,limited capacity of caching nodes, and limited bandwidth of in-network links. Existing solutions that rely on static configurations and average request arrival rates are insufficient to handle dynamic request patterns effectively. In this paper, we propose a dynamic collaborative video caching framework to be deployed in mobile networks. We decompose the caching problem into a content placement subproblem and a source-selection subproblem. We then develop SRS (System capacity Reservation Strategy) to solve the content placement subproblem, and LinkShare, an adaptive traffic-aware algorithm to solve the source selection subproblem. Our framework supports congestion avoidance and allows merging multiple requests for the same video into one request. We carry extensive simulations to validate the proposed schemes. Simulation results show that our SRS algorithm achieves performance within 1-3% of the optimal values and LinkShare significantly outperforms existing solutions.

Reexamination of constrains on the Maxwell-Boltzmann distribution by Helioseismology

Nuclear reactions in stars occur between nuclei in the high-energy tail of the energy distribution and are sensitive to possible deviations from the standard equilibrium thermal-energy distribution, the well-known Maxwell-Boltzmann Distribution (textsf{MBD}). In a previous paper published in Physics Letters 441B(1998)291, DeglInnocenti {it et al}. made strong constrains on such deviations with the detailed helioseismic information of the solar structure. With a small deviation parameterized with a factor exp$[{-delta (E/kT)^2}]$, it was shown $delta$ restricted between -0.005 and +0.002. These constrains have been carefully reexamined in the present work. We find that a normalization factor was missed in the previous modified textsf{MBD}. In this work, the normalization factor $c$ is calculated as a function of $delta$. It shows the factor $c$ is almost unity within the range 0$< delta leq$0.002, which supports the previous conclusion. However, it demonstrates that $delta$ cannot take a negative value from the normalization point of view. As a result, a stronger constraint on $delta$ is defined as 0$leq delta leq$0.002. The astrophysical implication on the solar neutrino fluxes is simply discussed based on a positive $delta$ value of 0.003. The reduction of the $^7$Be and $^8$B neutrino fluxes expected from the modified textsf{MBD} can possibly shed alternative light on the solar neutrino problem. In addition, the resonant reaction rates for the $^{14}$N($p$,$gamma$)$^{15}$O reaction are calculated with a standard textsf{MBD} and a modified textsf{MBD}, respectively. It shows that the rates are quite sensitive even to a very small $delta$. This work demonstrates the importance and necessity of experimental verification or test of the well-known textsf{MBD} at high temperatures.

Exploration of hyperfine interaction between constituent quarks via eta productions

In this work, the different exchange freedom, one gluon, one pion or Goldstone boson, in constituent quark model is investigated, which is responsible to the hyperfine interaction between constituent quarks, via the combined analysis of the eta production processes, $pi^{-}prightarroweta n$ and $gamma prightarroweta p$. With the Goldstone-boson exchange, as well as the one-gluon or one-pion exchange, both the spectrum and observables, such as, the differential cross section and polarized beam asymmetry, are fitted to the suggested values of Particle Data Group and the experimental data. The first two types of exchange freedoms give acceptable description of the spectrum and observables while the one pion exchange can not describe the observables and spectrum simultaneously, so can be excluded. The experimental data for the two processes considered here strongly support the mixing angles for two lowest S11 sates and D13 states as about -30 and 6 degree respectively.

$eta$ production off the proton in a Regge-plus-chiral quark approach

A chiral constituent quark model approach, embodying s- and u-channel exchanges,complemented with a Reggeized treatment for t-channel is presented. A model is obtained allowing data for $pi^- p to eta n$ and $gamma p to eta p$ to be describe satisfactorily. For the latter reaction, recently released data by CLAS and CBELSA/TAPS Collaborations in the system total energy range $1.6 lesssim W lesssim 2.8$ GeV are well reproduced due to the inclusion of Reggeized trajectories instead of simple $rho$ and $omega$ poles. Contribution from missing resonances is found to be negligible in the considered processes.

Study of $eta$ photoproduction on the proton in a chiral constituent quark approach via one-gluon-exchange model

A formalism based on a chiral quark model ($chi$QM) approach complemented with a one-gluon exchange model, to take into account the breakdown of the $SU(6)otimes O(3)$ symmetry, is presented. The configuration mixing of wave functions for nucleon and resonances are derived. % With few adjustable parameters, differential cross-section and polarized beam asymmetry for the $gamma p to eta p$ process are calculated and successfully compared with the data in the centre-of-mass energy range from threshold up to 2 GeV. The known resonances $S_{11}(1535)$, $S_{11}(1650)$, $P_{13}(1720)$, $D_{13}(1520)$, and $F_{15}(1680)$, as well as two new $S_{11}$ and $D_{15}$ resonances are found to be dominant in the reaction mechanism. Besides, connections among the scattering amplitudes of the $chi$QM approach and the helicity amplitudes, as well as decay widths of resonances are established. Possible contributions from the so-called missing resonances are investigated and found to be negligible.