In this paper, we present the simultaneous measurement of the strain and temperature during cures of various composite laminates using fiber Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPI) hybrid sensors. The characteristic matrix of the hybrid sensor is derived analytically. For the fabrication of the three types of graphite/epoxy composite laminate, two FBG/EFPI hybrid sensors were embedded in each composite laminate in two mutually perpendicular directions. We performed the real-time measurement of fabrication strains and temperatures at two points within the composite laminates during the curing process in an autoclave. Through these experiments, FBG/EFPI sensors are proven to be a good choice for efficient smart monitoring of composite structures.

Hadwiger's conjecture asserts that if a simple graph G has no K t+1 minor, then its vertex set V (G) can be partitioned into t stable sets. This is still open, but we prove under the same hypotheses that V (G) can be partitioned into t sets X 1 , . . . , X t , such that for 1 ≤ i ≤ t, the subgraph induced on X i has maximum degree at most a function of t. This is sharp, in that the conclusion becomes false if we ask for a partition into t − 1 sets with the same property.

In this paper, we present a simultaneous measurement of strain and temperature during and after cure of unsymmetric cross-ply composite laminate using fiber optic sensors. Fiber Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPI) hybrid sensors are used to measure those measurands. The characteristic matrix of the sensor is derived analytically and measurements can be done without sensor calibration experiments. A wavelength-swept fiber laser is utilized as a light source. Two FBG/EFPI hybrid sensors are embedded in a graphite/epoxy unsymmetric cross-ply composite laminate in different directions and different locations. We perform the real time measurement of fabrication strains and temperatures at two points within the composite laminate during the cure process in an autoclave. Also, the thermal strains and temperatures of the fabricated unsymmetric laminate are measured afterward in a thermal chamber. Through these experiments, FBG/EFPI sensors are proven to be an efficient choice for smart monitoring of composite structures.

No abstract

Background: In robotic surgical systems, commercial master devices have limitations owing