34 research outputs found
Electrodeposition of CuNiS as battery type electrode for supercapacitor applications
No full textThis study focuses on the high-performance, binder-free electrodes on nickel foam by simple cathodic electrodeposition using nickel chloride, copper sulfate, and thiourea solution as aqueous electrolytes. The CuS, NiS, and NiCuS electrodes synthesized by cathodic electrodeposition were characterized by X-ray diffraction, energy dispersive spectra, and scanning electron microscopy. The electrochemical performance of the synthesized positive electrodes was investigated in aqueous potassium hydroxide electrolyte by widespread electroanalytical techniques such as cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The electrochemical tests revealed that the synthesized electrode materials exhibited significant reversible redox reactions. Among the produced electrodes, CuNiS exhibited high specific capacitance (1026.9 F g−1 at 5 mV s−1; 1338.5 F g−1 at 1 A g−1 current density). The produced NiCuS//activated carbon supercapacitor achieved 890 W kg−1 power and 14.9 Wh kg−1 energy density in the potential range from 0 to 1.40 V. The asymmetric supercapacitor reached 157.8 % of the initial discharge capacity at the end of 5000 charge-discharge cycles. The results of this study indicate that the electrodes produced by the cathodic electrochemical deposition method have excellent potential for use as positive electrodes in supercapacitor applications
Cunis, Maria C. (Death, 1866-08-24)
No full textAddress: 213 Race St.Age at death: 1 yr257/Pg. 96/1866/F W S/Cinti, O/Dr./F.H./Cem.Original record filed in drawer labeled 'CRUSE-DAG'
Precision Position Control of the DelFly II Flapping-wing Micro Air Vehicle in a Wind-tunnel
No full textFlapping-wing MAVs represent an attractive alternative to conventional designs with rotary wings, since they promise a much higher efficiency in forward flight. However, further insight into the flapping-wing aerodynamics is still needed to get closer to the flight performance observed in natural fliers. Here we present the first step necessary to perform a flow visualization study of the air around the flapping wings of a DelFly II MAV in-flight: a precision position control of flight in a wind-tunnel. We propose a hierarchical control scheme implemented in the open-source Paparazzi UAV autopilot software. Using a decoupling, combined feed-forward and feed-back control approach as a core, we were able to achieve a precision of 2:5 cm for several seconds, which is much beyond the requirements for a time resolved stereo PIV technique.Control & Simulatio
Accurate position control of a flapping-wing robot enabling free-flight flow visualisation in a wind tunnel
No full textFlow visualisations are essential to better understand the unsteady aerodynamics of flapping wing flight. The issues inherent to animal experiments, such as poor controllability and unnatural flapping when tethered, can be avoided by using robotic flyers that promise for a more systematic and repeatable methodology. Here, we present a new flapping-wing micro air vehicle (FWMAV)-specific control approach that, by employing an external motion tracking system, achieved autonomous wind tunnel flight with a maximum root-mean-square position error of 28 mm at low speeds (0.8–1.2 m/s) and 75 mm at high speeds (2–2.4 m/s). This allowed the first free-flight flow visualisation experiments to be conducted with an FWMAV. Time-resolved stereoscopic particle image velocimetry was used to reconstruct the three-dimensional flow patterns of the FWMAV wake. A good qualitative match was found in comparison to a tethered configuration at similar conditions, suggesting that the obtained free-flight measurements are reliable and meaningful.Control & SimulationAerodynamic
The energy calibration of x‐ray absorption spectra using multiple‐beam diffraction
No full textA new method for calibrating the energy scale of x‐ray absorption spectra from an energy dispersive spectrometer has been developed. Distinct features in the diffracted intensity of the curved silicon crystal monochromator have been assigned to multiple‐beam diffraction. The photon energies of these structures can be calculated if the precise spacing of the diffracting planes and the orientation of the crystal relative to the incident synchrotron radiation are known. The evaluation of Miller indices of operative reflections and the calculation of the corresponding photon energy is presented. The assignment of operative reflexes is simplified if the monochromator crystal can be rotated around the main diffracting vector H
Piecewise Polynomial Model of the Aerodynamic Coefficients of the Cumulus One Unmanned Aircraft
No full textThis document illustrates a piecewise polynomial model for Cumulus One, based on continuous fluid dynamics simulation, derived using the pwpfit toolbox. The model has been developed in a joint project of Sky-Watch and the University of Aalborg
Piecewise Polynomial Model of the Aerodynamic Coefficients of the Cumulus One Unmanned Aircraft
No full textThis document illustrates a piecewise polynomial model for Cumulus One, based on continuous fluid dynamics simulation, derived using the pwpfit toolbox. The model has been developed in a joint project of Sky-Watch and the University of Aalborg
Piecewise Polynomial Model of the Aerodynamic Coefficients of the Cumulus One Unmanned Aircraft
No full textThis document illustrates a piecewise polynomial model for Cumulus One, based on continuous fluid dynamics simulation, derived using the pwpfit toolbox. The model has been developed in a joint project of Sky-Watch and the University of Aalborg
