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We propose a novel defect induced planar meta-atom that supports multiple Fano resonances in a defective corrugated metallic disk (CMD) structure. Numerical and experimental results reveal that multiple Fano resonances can be excited at terahertz frequencies when the symmetry of the CMD is broken by introducing a small angular defect. These multiple Fano resonances result from mutual coupling between the bright dipolar mode evoked by the edge of the wedge-shaped slice and dark multipole spoof localized surface plasmon modes. Furthermore, the influence of the angle of defect on the Q-factor and the resonance intensity of the quadrupolar resonance peak is investigated.Large values of figure of merit are obtained due to higher Fano resonance intensity and Q-factor.Results from two defective slices in the CMD structure validate the mechanism of the observed phenomenon. Our findings would enable a defect induced Fano resonance platform for bio sensing, terahertz domain filtering, and strong light-matter interactions.

This paper introduces a new feedback algorithm for steering a point robot through an obstacle field. The key innovation is the use of a circulatory field to rotate the robot path around the obstacles instead of the common potential field which repels the robot. This idea is motivated by a charged particle in a magnetic field generated by a current flowing around the obstacle. In constrast, the potential field approach is associated with a repulsive static electric field generated by charges of the same polarity as the robot, on the obstacle. The circulatory field does not generate any spurious local minimum as it does not change the total energy of the system. By combining with an attractive potential field associated with the desired destination, this method achieves global convergence while avoiding collisions with obstacles.

Terahertz sensing of highly absorptive aqueous solutions remains challenging due to strong absorption of water in the terahertz regime. Here, we experimentally demonstrate a cost-effective metamaterial-based sensor integrated with terahertz time-domain spectroscopy for highly absorptive water-methanol mixture sensing. This metamaterial has simple asymmetric wire structures that support multiple resonances including a fundamental Fano resonance and higher order dipolar resonance in the terahertz regime. Both the resonance modes have strong intensity in the transmission spectra which we exploit for detection of the highly absorptive water-methanol mixtures. The experimentally characterized sensitivities of the Fano and dipole resonances for the water-methanol mixtures are found to be 160 and 305 GHz/RIU, respectively. This method provides a robust route for metamaterial-assisted terahertz sensing of highly absorptive chemical and biochemical materials with multiple resonances and high accuracy.

Under the Joint Precision Airdrop System program, a Draper Laboratory autonomous Guidance, Navigation, and Control (GN&C) software package that enables precision payload airdrop delivery using large parafoils has been developed in prototype form and successfully flight tested. The modular software design is structured to accommodate parafoil airdrop systems for payloads ranging from under 2,000 lb to over 30,000 lb. The initial GN&C software implementation has been demonstrated on the Para-Flite Dragonfly 10,000 lb-class parafoil using an Airborne Guidance Unit (AGU) provided by Wamore, Inc. and an avionics package provided by RoboTek. Among the primary avionics selection criteria was low component cost, resulting in use of a processor with very limited data throughput capability. To accommodate the processor limits, the Guidance algorithm includes table driven trajectory data that guides the parafoil through precision final-descent maneuvers while imposing very limited processor throughput burden. The GN&C algorithms and associated mission planning software have also been incorporated into the Precision Airdrop System laptop personal computer. This accommodates easy, in the field, ground loading of the GN&C software onto the AGU and enables PADS updates of the airdrop system mission files during flight of the carrier aircraft to the airdrop release point. The details of the GN&C design and flight test results to date are discussed.

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