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In its simplest form, the human postural control system can be described as a closed-loop control system consisting of a plant (body segments and musculotendon actuators) and feedback. Previous efforts to understand the contributions of plant and feedback employed techniques to "open the loop" which is problematic with the study of posture because the plant is unstable without feedback. In the present experiment, a closed-loop system identification method was used to "open the loop" without removal of sensory feedback. Subjects stood on a movable platform facing a visual scene, both of which were capable of rotation about an axis coaxial with the subject's ankles. The visual stimulus (present all trials) consisted of a 10-frequency sum-of-sines while movement of the support surface consisted of the following conditions: 1. Stationary; 2. Sway-referenced to the subject's body sway; 3. 10-frequency sum-of-sines; 4. Combined sway-referenced and sum-of-sines. Closed-loop frequency response functions were calculated for visual stimulus to EMG and visual stimulus to body sway angle. The open loop frequency response function for the plant was determined by dividing the frequency response functions, mathematically canceling the effects of feedback. With respect to the visual stimulus, gains for the leg segment showed no differences between the four platform conditions. Phase for the stationary condition was lower at the higher stimulus driving frequencies than for any of the moving platform conditions. In contrast, trunk segment gains were lower for the sway-referenced conditions at lower stimulus frequencies than for the stationary and sum-of-sines conditions. Phase showed a slight lead of the legs over the trunk for the sway-referenced conditions. The phase relationship between the trunk and leg segments, typically in-phase below ~1 Hz and anti-phase above ~1 Hz, showed a gradual transition at a lower frequency for the sway-referenced conditions than for the stationary or

This paper studies the routing and wavelength assignment (RWA) problem in multi-segment optical networks. The notion of network segment is referred to any part of the network that requires special consideration of wavelength routing such as separate administrative domains in a large scale optical network, sub-networks run by various service providers, etc. In multi-segment optical networks, each segment has different resource availability or hardware characteristics. The differences between multi-segment optical networks and homogeneous optical networks are discussed. We then present a resource abstraction technique called blocking island and define a multi-segment blocking island graph (BIG) network model. Using a minimum splitting routing heuristic introduced in the context of the blocking island paradigm in conjunction with the multi-segment BIG model, we propose a general RWA algorithm that takes a combined view of the network resource to integrate routing, wavelength assignment and gateway selection in a single routing framework. In the simulation, we demonstrate the effectiveness of our proposed algorithm by comparing it with other state-of-the-art heuristics in this area.

This paper studies the routing and wavelength assignment (RWA) problem in multi-segment optical networks. The notion of network segment is referred to any part of the network that requires special consideration of wavelength routing such as separate administrative domains in a large scale optical network, sub-networks run by various service providers, etc. In multi-segment optical networks, each segment has different resource availability or hardware characteristics. The differences between multi-segment optical networks and homogeneous optical networks are discussed. We then present a resource abstraction technique called blocking island and define a multi-segment blocking island graph (BIG) network model. Using a minimum splitting routing heuristic introduced in the context of the blocking island paradigm in conjunction with the multi-segment BIG model, we propose a general RWA algorithm that takes a combined view of the network resource to integrate routing, wavelength assignment and gateway selection in a single routing framework. In the simulation, we demonstrate the effectiveness of our proposed algorithm by comparing it with other state-of-the-art heuristics in this area.

This paper studies the routing and wavelength assignment (RWA) problem in multi-segment optical networks. The notion of network segment is referred to any part of the network that requires special consideration of wavelength routing such as separate administrative domains in a large scale optical network, sub-networks run by various service providers, etc. In multi-segment optical networks, each segment has different resource availability or hardware characteristics. The differences between multi-segment optical networks and homogeneous optical networks are discussed. We then present a resource abstraction technique called blocking island and define a multi-segment blocking island graph (BIG) network model. Using a minimum splitting routing heuristic introduced in the context of the blocking island paradigm in conjunction with the multi-segment BIG model, we propose a general RWA algorithm that takes a combined view of the network resource to integrate routing, wavelength assignment and gateway selection in a single routing framework. In the simulation, we demonstrate the effectiveness of our proposed algorithm by comparing it with other state-of-the-art heuristics in this area.

In this paper, we study the routing and wavelength assignment (RWA) problem in multi-segment optical networks. In multi-segment optical networks, each segment has different resource availability or hardware characteristics. The differences between multi-segment optical networks and homogeneous optical networks are discussed. We then present a resource abstraction technique called Blocking Island and define a multi-segment BIG (Blocking Island Graph) network model. Using a minimum splitting routing heuristic introduced in the context of the blocking island paradigm in conjunction with the multi-segment BIG model, we propose a general RWA algorithm that takes a combined view of the network resource to integrate routing, wavelength assignment and gateway selection in a single routing framework. In the simulation we demonstrate the effectiveness of our proposed algorithm by comparing it with other state-of-the-art heuristics in this area.

In this paper, we study the routing and wavelength assignment (RWA) problem in multi-segment optical networks. In multi-segment optical networks, each segment has different resource availability or hardware characteristics. The differences between multi-segment optical networks and homogeneous optical networks are discussed. We then present a resource abstraction technique called Blocking Island and define a multi-segment BIG (Blocking Island Graph) network model. Using a minimum splitting routing heuristic introduced in the context of the blocking island paradigm in conjunction with the multi-segment BIG model, we propose a general RWA algorithm that takes a combined view of the network resource to integrate routing, wavelength assignment and gateway selection in a single routing framework. In the simulation we demonstrate the effectiveness of our proposed algorithm by comparing it with other state-of-the-art heuristics in this area.

In this paper, we study the routing and wavelength assignment (RWA) problem in multi-segment optical networks. In multi-segment optical networks, each segment has different resource availability or hardware characteristics. The differences between multi-segment optical networks and homogeneous optical networks are discussed. We then present a resource abstraction technique called Blocking Island and define a multi-segment BIG (Blocking Island Graph) network model. Using a minimum splitting routing heuristic introduced in the context of the blocking island paradigm in conjunction with the multi-segment BIG model, we propose a general RWA algorithm that takes a combined view of the network resource to integrate routing, wavelength assignment and gateway selection in a single routing framework. In the simulation we demonstrate the effectiveness of our proposed algorithm by comparing it with other state-of-the-art heuristics in this area.