Dynamic analysis of magnetorheological elastomer configured sandwich structures

The work presented in this thesis is concerned with the investigation of the dynamic behaviour of magnetorheological elastomers (MREs) and smart sandwich structures. An extensive review, covering existing smart materials and their applications, has highlighted that smart materials and structures can be applied to large scale structures. Comprehensive experimental tests have been carried out in order to gain knowledge and data on the dynamic shear properties and behaviour of stiffness change of MRE and MRE cored adaptive sandwich beam structures depending on magnetic fields. Dynamic shear property tests with different curing stages have been enhanced to obtain various properties. The new developed forced vibration test rig enabled forced vibration tests of MRE embedded sandwich beam with various aspects such as different magnetic field strength, various oscillations of force amplitudes, boundary conditions and damping effects under localised magnetic fields to be made. In parallel to these experimental investigations, a new theoretical model was developed by combining the magnetisation effects on iron particles in terms of the curing times. In addition, a new macro scale modelling approach for rubber like materials (nonlinear behaving materials) was made by adopting FEA analysis to obtain the optimum volume of pores and size of iron particles to enhance the performance of MREs. A higher order sandwich beam theory is extended to include damping properties of MRE. It has been demonstrated that a higher order sandwich beam theory appears to be the most versatile and accurate modelling method for a sandwich beam with an MRE core material. The results from higher order theory have been combined with a power flow analysis for the smart floating sandwich raft vibration isolation system. Finally, an experimental study was performed to illustrate the control capabilities of MRE adaptive vibration absorber for a propeller shaft in real time. From this research work, a better understanding of the dynamic behaviour of MRE embedded sandwich beam has been acquired

R-Pred: Two-Stage Motion Prediction Via Tube-Query Attention-Based Trajectory Refinement

Predicting the future motion of dynamic agents is of paramount importance to ensure safety or assess risks in motion planning for autonomous robots. In this paper, we propose a two-stage motion prediction method, referred to as R-Pred, that effectively utilizes both the scene and interaction context using a cascade of the initial trajectory proposal network and the trajectory refinement network. The initial trajectory proposal network produces M trajectory proposals corresponding to M modes of a future trajectory distribution. The trajectory refinement network enhances each of M proposals using 1) the tube-query scene attention (TQSA) and 2) the proposal-level interaction attention (PIA). TQSA uses tube-queries to aggregate the local scene context features pooled from proximity around the trajectory proposals of interest. PIA further enhances the trajectory proposals by modeling inter-agent interactions using a group of trajectory proposals selected based on their distances from neighboring agents. Our experiments conducted on the Argoverse and nuScenes datasets demonstrate that the proposed refinement network provides significant performance improvements compared to the single-stage baseline and that R-Pred achieves state-of-the-art performance in some categories of the benchmark

Case Studies of Strategic Alliances in U.S. Beef Production

Calf marketing, commercial beef carcass, and natural/implant-free beef strategic alliances were examined via case study to determine alliance structure and whether each addressed risk, transaction costs, capital availability, and other concerns. All alliances were structured differently through vertical or horizontal coordination, and each had been established within the past 12 years. Alliance administrators reported that an advantage to cow-calf producers was higher cattle prices received relative to producers outside the alliances. The alliances reduced transaction costs and increased information flow among segments. Alliances did not specifically address risk or increased access to capital for technology adoption or expansion purposes.cattle industry, industry structure, risk, strategic alliances, transaction costs, Agribusiness, Livestock Production/Industries,