Unsteady Aerodynamic Interaction Between Rotor and Ground Obstacle

The mutual aerodynamic interaction between rotor wake and surrounding obstacles is complex, and generates high compensatory workload for pilots, degradation of the handling qualities and performance, and unsteady force on the structure of the obstacles. The interaction also affects the minimum distance between rotorcrafts and obstacles to operate safely. A vortex-based approach is then employed to investigate the complex aerodynamic interaction between rotors and ground obstacle, and identify the distance where the interaction ends, and this is also the objective of the GARTEUR AG22 working group activities. In this approach, the aerodynamic loads of the rotor blades are described through a panel method, and the unsteady behaviour of the rotor wake is modelled using a vortex particle method. The effects of the ground plane and obstacle are accounted for via a viscous boundary model. The method is then applied to a “Large” and a “Wee” rotor near the ground and obstacle, and compared with the earlier experiments carried out at the University of Glasgow. The results show that the predicted rotor induced inflow and flow field compare reasonably well with the experiments. Furthermore, at certain conditions the tip vortices are pushed up and re-injected into the rotor wake due to the effect of the obstacle resulting in a recirculation. Moreover, contrary to without the obstacle case, the peak and thickness of the radial outwash near the obstacle is smaller due to the barrier effect of the obstacle, and an up-wash is observed. Additionally, as the rotor closes to the obstacle, the rotor slipstreams impinge directly on the obstacle, and the up-wash near the obstacle is faster, indicating a stronger interaction between the rotor wake and the obstacle. Also, contrary to the case without the obstacle, the fluctuations of the rotor thrust, rolling and pitching moments are obviously strengthened. When the distance between the rotor and the obstacle is larger than 3R, the effect of the obstacle is small

Commonalities and differences between service and manufacturing supply chains: Combining operations management studies with supply chain management

The service sector of the US economy has been gaining importance. As the service sector evolves, the study of service supply chain starts to gain attention. In this study, we conduct an exploratory review on the studies of manufacturing and service supply chains. We focus on the studies that explore the differences and commonalities between manufacturing and service supply chains. We combine operations management literature with supply chain studies in order to provide an interdisciplinary framework that brings up both the operational and strategic views on the management commonalities and differences between the two types of supply chains

An Exploratory Study to Improve Sales Operations When Selling Multiple Prescription Drugs

This paper explores the importance of integrating knowledge with quantitative modeling process to improve sales operations in multiple product selling situations in the pharmaceutical industry. A knowledge-based approach is proposed to minimize challenges in detailing multiple products to physicians who are more and more difficult accessing in recent years. The performance of this new approach is compared against the traditional approach via actual implementation by the firm that is sponsoring the research. Results based on three months of implementation indicate that the knowledge-based approach performs significantly better with increasing the number of responsive physicians by 71% and profit by 9%