In this paper, we discuss the evolution of the optical beam in nonlocal cubic nonlinear media, modeled by the nonlocal nonlinear Schrödinger equation ͑NNLSE͒. A different approximate model to the NNLSE is presented for the strongly nonlocal media with arbitrary response functions. An exact analytical solution of the model is obtained, and a spatial soliton is found to exist. A different phenomenon is revealed that the phase shift of such a nonlocal optical spatial soliton can be very large comparable to its local counterpart. The stability of the solution is rigorously proved. The comparisons of our analytical solution with the numerical simulation of the NNLSE, as well as with Snyder-Mitchell ͑linear͒ model ͓A.

The neutral beam injection (NBI) system was developed on the Experimental Advanced Superconducting Tokamak (EAST) for plasma heating and current driving. This paper presents the brief history, design, development, and the main experimental results of the R&D of neutral beam injector on the test bed and on EAST. In particular, it will describe: (1) how the two beamlines with a total beam power of 8 MW were developed; (2) the design of the EAST-NBI system including the high power ion source, main vacuum chamber, inner components, beam diagnostic system and sub-system; (3) the experimental results of beamline-1 on the summer campaign of EAST in 2014 and, (4) the status of beamline-2 and the future plan of EAST-NBIs.

Abstract:The entropy generation analysis of fully turbulent convective heat transfer to nanofluids in a circular tube is investigated numerically using the Reynolds Averaged Navier-Stokes (RANS) model. The nanofluids with particle concentration of 0%, 1%, 2%, 4% and 6% are treated as single phases of effective properties. The uniform heat flux is enforced at the tube wall. To confirm the validity of the numerical approach, the results have been compared with empirical correlations and analytical formula. The self-similarity profiles of local entropy generation are also studied, in which the peak values of entropy generation by direct dissipation, turbulent dissipation, mean temperature gradients and fluctuating temperature gradients for different Reynolds number as well as different particle concentration are observed. In addition, the effects of Reynolds number, volume fraction of nanoparticles and heat flux on total entropy generation and Bejan number are discussed. In the results, the intersection points of total entropy generation for water and four nanofluids are observed, when the entropy generation decrease before the intersection and increase after the intersection as the particle concentration increases. Finally, by definition of E p , which combines the first law and second law of thermodynamics and attributed to evaluate the real performance of heat transfer processes, the optimal Reynolds number Re op corresponding to the best performance and the advisable Reynolds number Re ad providing the appropriate Reynolds number range for nanofluids in convective heat transfer can be determined.