Ship berthing is a specific maneuver operation. The flow around a berthing ship and the forces acting on the hull are quite different from those for a ship in normal navigation. By solving the unsteady Reynolds-Averaged Navier-Stokes （RANS） equations, the transient flow field around a ship undergoing unsteady lateral motion is simulated and the varying lateral hydrodynamic force acting on the hull is evaluated in this article. The numerical results obtained with different turbulence models are analyzed and compared with experimental results and other numerical results published in literature, and a turbulence model more suitable for simulation of the viscous flow around a ship undergoing unsteady berthing is determined.
In order to generate the three-dimensional (3-D) hull surface accurately and smoothly,a mixed method which is made up of non-uniform B-spline together with an iterative procedure was developed.By using the iterative method the data points on each section curve are calculated and the generalized waterlines and transverse section curves are determined.Then using the non-uniform B-spline expression,the control vertex net of the hull is calculated based on the generalized waterlines and section curves.A ship with tunnel stern was taken as test case.The numerical results prove that the proposed approach for geometry modeling of 3-D ship hull surface is accurate and effective.
The future generation networks or 4G networks constitute of varied technologies converged over the Internet protocol version 6(IPv6) core. The 4G networks offer varied services over different interfaces to the user nodes. Mobility management in 4G networks is an issue that exists. The handover protocols for mobility management in 4G networks that currently exist, do not consider wireless signal degradation during handover operations. This paper introduces the Noise Resilient Reduced Registration Time Care of Mobile IP(NR RRTC:MIP) protocol for handover management. A handover decision algorithm based on the signal strength measured by the user nodes is considered in the NR RRTC: MIP protocol. A simulation study is discussed in the paper to evaluate the performance of the NR RRTC: MIP protocol. The results obtained from the simulation study prove that the NR RRTC: MIP protocol effectively reduces handover latencies and improves network performance.
BHASKAR Subbe GowdaSATISH KUMAR Gandluru Arthur EdwinRAMANA REDDY Patil
System identification is an effective way for modeling ship manoeuvring motion and ship manoeuvrability prediction. Support vector machine is proposed to identify the manoeuvring indices in four different response models of ship steering motion, including the first order linear, the first order nonlinear, the second order linear and the second order nonlinear models. Predictions of manoeuvres including trained samples by using the identified parameters are compared with the results of free-running model tests. It is discussed that the different four categories are consistent with each other both analytically and numerically. The generalization of the identified model is verified by predicting different untrained manoeuvres. The simulations and comparisons demonstrate the validity of the proposed method.
A 3D rankine panel method was developed for calculating the linear wave-making resistance of a tri-maran with Wigley hulls. In order to calculate the normal vector and derivative of the body surface accurately, non-uniform rational B-spline (NURBS) was adopted to represent body surface and rankine source density. The radiation condition is satisfied using the numerical technology of staggered grids. Numerical results show that the linear wave-making resistance of the trimaran can be calculated effectively using this method.
