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BACKGROUND Recent work suggests that mixing in the small intestine takes place in central luminal and peripheral compartments. However, while movements of villi have been described, the mechanisms by which peripheral mixing are engendered remain unclear. METHODS We examined the disposition and movement of mucosa and associated villi during contractions of… (More)
When a logistics system is " self-organizing " it can function without significant intervention by managers, engineers, or software control. The social insects, such as ants or bees, provide models of self-organizing logistics systems that may be profitably emulated. We illustrate some of these ideas for the problem of balancing assembly lines.
In a network of subassembly lines, balance becomes more difficult to achieve as it requires that all subassembly lines be synchronized to produce at the same rate. We show how to adapt the ''bucket brigade'' protocol of work-sharing so that balance emerges spontaneously. 1. In-tree assembly networks Consider a network of subassembly lines such as shown in… (More)
A ssigning products to and retrieving them from proper storage locations are crucial decisions in minimizing the operating cost of a unit-load warehouse. The problem becomes intractable when the warehouse faces variable supply and uncertain demand in a multiperiod setting. We assume a factor-based demand model in which demand for each product in each period… (More)
Acknowledgments I thank Professor John Bartholdi for his guidance and financial support. Without him the accomplishment of this thesis would have been impossible. Special thanks must go to Professor Donald Eisenstein, who always inspires me on my work, for co-advising me.
Multiple particle-tracking techniques were used to quantify the thermally driven motion of ensembles of naked polystyrene (0.5 µm diameter) microbeads in order to determine the microrheological characteristics around the gut mucosa. The microbeads were introduced into living ex vivo preparations of the wall of the terminal ileum and proximal colon of the… (More)
Workers in a bucket brigade production system perform unproductive travel when they walk to get more work from their colleagues. We introduce a new design of bucket brigades to reduce unproductive travel. Under the new design, each worker works on one side of an aisle when he proceeds in one direction and works on the other side when he proceeds in the… (More)
Assigning products to and retrieving them from proper storage locations in a unit-load warehouse are crucial in minimizing its operating cost. The problem becomes intractable when the warehouse faces uncertain demand in a dynamic setting. We assume a factor-based demand model in which demand for each product in each period is affinely dependent on some… (More)