This paper addresses the development of a novel antisway control approach for marine shipboard cranes, offering stability, safety, and efficiency during lifting, handling, transportation, and other manipulation. The proposed idea consists of the development of an integrated system with control strategies to both reduce the effect of three-dimensional payload pendulation and to minimize wave impact during shipboard crane manipulation. We propose to use a control mechanism based on energy dissipation. The simulation results confirm the principle and effectiveness of the proposed methods for damping out pendulation. In future work, we aim to minimize wave impact on the payload by reducing the dynamic forces through controlling the length of the hoist cable while adapting to the lateral wave velocity. During the final phase of this project, the proposed control strategy will be implemented as a real physical prototype for controlling different kinds of shipboard cranes.

By allowing human users to manipulate simulation models and steer their execution at run time, interactive simulation systems (ISS) are essential to realise problem solving environments (PSE) for studying complex problems that are difficult to investigate using conventional methodologies. However, the complexity of system development critically hampers the construction of ISSs; when a scientist explores a complex problem, he has to spend much of his effort on various implementation issues, instead of on the investigation of the experiment itself A layered framework for developing ISSs is crucial to hide the underlying development issues from scientists and to allow them to focus on the high-level behaviour of the system. In this paper we investigate a solution to the complexity issues in ISSs based on the separation of application logic control and system functionality. We implement a proof of concept architecture, called interactive simulation system conductor, based on high level architecture (HLA), and demonstrate that this architecture allows a scientist to quickly adapt the system to his needs in a rapid prototyping approach. A medical application for planning surgical operations is used as a test case.

Hybrid architectures are systems where a high performance general purpose computer is coupled to one or more special purpose devices (SPDs). Such a system can be the optimal choice for several fields of computational science. Configuring the system and finding the optimal mapping of the application tasks onto the hybrid machine often is not straightforward. Performance modeling is a tool to tackle and solve these problems. We have developed a performance model to simulate the behavior of a hybrid architecture consisting of a parallel multiprocessor where some nodes are the host of a GRAPE board. GRAPE is a very high performance SPD used in computational astrophysics. We validate our model on the architecture at our disposal, and show examples of predictions that our model can produce.

We investigate the performance of the time warp kernel APSIS when running on various communication layers, in particular on a wide-area grid. Several cancellation strategies are tried, among them the lazy cancellation and a little known bulk anti-messages optimization. Our experiments with an Ising spin simulation indicate that the slowdown caused by high latency networks, while significant, is not catastrophic; and that it can be significantly reduced using the lazy cancellation. Experiments suggest that further improvements can be expected if a more elaborate communication infrastructure is put in place.

Abstract The paper provides an overview of an experimental, Grid‐like computing environment, Polder, and its components. Polder offers high‐performance computing and interactive simulation facilities to computational science. It was successfully implemented on a wide‐area cluster system, the Distributed ASCI Supercomputer. An important issue is an efficient management of resources, in particular multi‐level scheduling and migration of tasks that use PVM or sockets. The system can be applied to interactive simulation, where a cluster is used for high‐performance computations, while a dedicated immersive interactive environment (CAVE) offers visualization and user interaction. Design considerations for the construction of dynamic exploration environments using such a system are discussed, in particular the use of intelligent agents for coordination. A case study of simulatedabdominal vascular reconstruction is subsequently presented: the results of computed tomography or magnetic resonance imaging of a patient are displayed in CAVE, and a surgeon can evaluate the possible treatments by performing the surgeries virtually and analysing the resulting blood flow which is simulated using the lattice‐Boltzmann method. Copyright © 2002 John Wiley & Sons, Ltd.