Current Issue : January - March Volume : 2020 Issue Number : 1 Articles : 5 Articles
A low-profile (0.21Lambda g*0.35Lambda g* 0.02Lambda g) and a simply-structured frequency-switchable\nantenna with eight frequency choices is presented in this paper. The radiating structure (monopole)\nis printed on a 1.6-mm thicker, commercially-available substrate of FR-4........................
This paper deals with the reconfiguration analysis of a 3-DOF (degrees-of-freedom) parallel\nmanipulator (PM) which belongs to the cylindrical parallel mechanisms family. The PM is composed\nof a base and a moving platform shaped as equilateral triangles connected by three serial kinematic\nchains (legs). Two legs are composed of two universal (U) joints connected by a prismatic (P) joint.\nThe third leg is composed of a revolute (R) joint connected to the base, a prismatic joint and universal\njoint in sequence. A set of constraint equations of the 1-RPU-2-UPU PM is derived and solved\nin terms of the Euler parameter quaternion (a.k.a. Euler-Rodrigues quaternion) representing the\norientation of the moving platform and of the Cartesian coordinates of the reference point on\nthe moving platform. It is found that the PM may undergo either the 3-DOF PPR or the 3-DOF\nplanar operation mode only when the base and the moving platform are identical. The transition\nconfiguration between the operation modes is also identified....
A novel reconfigurable filter antenna with three ports for three dependent switchable\nstates for impulse radio-ultrawideband (IR-UWB)/wireless local area network (WLAN)/worldwide\ninteroperability for microwave access (WiMAX) applications is presented in this paper. Three\npositive-intrinsic-negative diodes, controlled by direct current, are employed to realize frequency\nreconfiguration of one ultra-wideband state and two narrowband states (2.4 GHz and 3.5 GHz). The\ntime domain characteristic of the proposed antenna in the ultra-wideband state is studied, because of\nthe features of the IR-UWB system. The time domain analysis shows that the reconfigurable filtering\nantenna in the wideband state performs similarly to the original UWB antenna. The compact size,\nlow cost, and expanded reconfigurable filtering features make it suitable for IR-UWB systems that are\nintegrated with WLAN/WiMAX communications....
We present results of our investigations on nickel silicidation of top-down fabricated\nsilicon nanowires (SiNWs). Control over the silicidation process is important for the application\nof SiNWs in reconfigurable field-effect transistors. Silicidation is performed using a rapid thermal\nannealing process on the SiNWs fabricated by electron beam lithography and inductively-coupled\nplasma etching. The effects of variations in crystallographic orientations of SiNWs and different\nNW designs on the silicidation process are studied. Scanning electron microscopy and transmission\nelectron microscopy are performed to study Ni diffusion, silicide phases, and silicide -silicon interfaces.\nControl over the silicide phase is achieved together with atomically sharp silicide -silicon interfaces.\nWe find that {111} interfaces are predominantly formed, which are energetically most favorable\naccording to density functional theory calculations. However, control over the silicide length remains\na challenge....
Aircraft surface inspection includes detecting surface defects caused by corrosion and cracks and stains from the oil spill, grease, dirt\nsediments, etc. In the conventional aircraft surface inspection process, human visual inspection is performed which is timeconsuming\nand inefficient whereas robots with onboard vision systems can inspect the aircraft skin safely, quickly, and\naccurately. This work proposes an aircraft surface defect and stain detection model using a reconfigurable climbing robot and an\nenhanced deep learning algorithm. A reconfigurable, teleoperated robot, named as â??Kiropter,â? is designed to capture the aircraft\nsurface images with an onboard RGB camera. An enhanced SSD MobileNet framework is proposed for stain and defect\ndetection from these images. A Self-filtering-based periodic pattern detection filter has been included in the SSD MobileNet\ndeep learning framework to achieve the enhanced detection of the stains and defects on the aircraft skin images. The model has\nbeen tested with real aircraft surface images acquired from a Boeing 737 and a compact aircraftâ??s surface using the teleoperated\nrobot. The experimental results prove that the enhanced SSD MobileNet framework achieves improved detection accuracy of\naircraft surface defects and stains as compared to the conventional models....
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