Strong Diffusion Effect of Charm Quarks on J/ψJ/\psi Production in Pb-Pb collisions at the LHC

We study the $J/\psi$ production based on coalescence model at $\sqrt{s_{NN}}$ = 2.76 and 5.02 TeV Pb-Pb collisions. With the colliding energy increasing from 2.76 TeV to 5.02 TeV, the number of charm pairs is enhanced by more than 50%. However, the ratio of $J/\psi$ inclusive nuclear modification factors $R^{5.02TeV}_{AA}/R^{2.76TeV}_{AA}$ is only about 1.1 $\sim$ 1.2. We find that the regeneration of $J/\psi$ is proportional to the densities of charm and anti-charm quarks, instead of their total numbers. The charm quark density is diluted by the strong expansion of quark gluon plasma, which suppresses the combination probability of heavy quarks and $J/\psi$ regeneration. This effect is more important in higher colliding energies where QGP expansion is strong. We also propose the ratio $N_{J/\psi}/(N_D)^2$ as a measurement of $c$ and $\bar c$ coalescence probability, which is only affected by the heavy quark diffusions in QGP, and does not depend on the inputs such as cold nuclear matter effects and cross sections of charm quark production. Further more, we give the predictions at the energy of Future Circular Collider ($\sqrt{s_{NN}}$ = 39 TeV)

Color Filtering Localization for Three-Dimensional Underwater Acoustic Sensor Networks

Accurate localization for mobile nodes has been an important and fundamental problem in underwater acoustic sensor networks (UASNs). The detection information returned from a mobile node is meaningful only if its location is known. In this paper, we propose two localization algorithms based on color filtering technology called PCFL and ACFL. PCFL and ACFL aim at collaboratively accomplishing accurate localization of underwater mobile nodes with minimum energy expenditure. They both adopt the overlapping signal region of task anchors which can communicate with the mobile node directly as the current sampling area. PCFL employs the projected distances between each of the task projections and the mobile node, while ACFL adopts the direct distance between each of the task anchors and the mobile node. Also the proportion factor of distance is proposed to weight the RGB values. By comparing the nearness degrees of the RGB sequences between the samples and the mobile node, samples can be filtered out. And the normalized nearness degrees are considered as the weighted standards to calculate coordinates of the mobile nodes. The simulation results show that the proposed methods have excellent localization performance and can timely localize the mobile node. The average localization error of PCFL can decline by about 30.4% than the AFLA method.Comment: 18 pages, 11 figures, 2 table

Charmonium transport in the high-μB\mu_B medium

We employ the transport model coupled with hydrodynamic equations to study the charmonium dissociation and regeneration in the quark-gluon plasma (QGP) with the large baryon chemical potential in Au-Au collisions at the energies of $\sqrt{s_{NN}}=$ ($39$, $14.5$, $7.7$) GeV. The baryon chemical potential $\mu_B$ is encoded in both Debye mass characterizing the heavy-quark potential and also the equation of state (EoS) of the bulk medium respectively. After considering $\mu_B$-corrections in both heavy quarkonium and the QGP medium, we calculate the nuclear modification factor $R_{AA}$ of charmonium. And find the $\mu_B$ influence on charmonium production at $\sqrt{s_{NN}}$ = 39 and 14.5 GeV is negligible, while the $R_{AA}$ of charmonium is reduced clearly considering $\mu_B$ influence at $\sqrt{s_{NN}}=7.7$ GeV Au-Au collisions. It is crucial for studying charmonium production in low energy and also fixed-target heavy-ion collisions.Comment: 7 pages; 9 figure

Hydroelastic Response of Submerged Floating Tunnel

This research investigation addresses the analysis and numerical simulation of dynamic response of submerged floating tunnels (SFTs) under the influence of surface waves. As an innovative technical solution for waterway crossings, an SFT is usually considered as a slender structure restrained by cable system due to its large aspect ratio, i.e. ratio of length to diameter. Although an SFT is usually placed at a certain depth under the water surface, it is still susceptible to wave field due to its slenderness. In this research study, a three-dimensional finite element solving technique, using both Morison’s equation and modal analysis, is formulated to construct a hydroelastic model of an SFT and to determine its deformation considering the fluid-structure interactions. Two preliminary tunnel models for China and Japan, respectively, were studied by implementing the proposed methodology. In the first case study, a three-dimensional finite element model of the SFT prototype in Qiandao Lake (China) was built in Matlab and subsequently analyzed using mode decomposition to determine its natural frequencies and mode shapes. For each mode shape, Morison’s equation was employed to calculate fluid forces at each cross section along the tunnel for given surface wave conditions. Then in the frequency domain, a complex equation of motion was solved iteratively to address the convergence of the stiffness of the cable system. The total dynamic response of SFT was the sum of contributions from each mode component. Results obtained from Matlab were compared with findings from previous publications and numerical simulations in ABAQUS. Next, a generic pedestrian-aimed SFT proposed for Otaru Crossing in Japan was studied. Parametric studies were performed to evaluate the influence of configuration scheme of cable system and tunnel submerged depth on the dynamic response of SFT. Results show the importance of fundamental structural parameters in the SFT global performance and several key conclusions regarding parameter selections were drawn for engineering practices in design phase