5 research outputs found
Teaching ecosystem and environment and its effect on the environmental consciousness of grade 9 students: A preliminary self study
No full textThe effect of integrating cooperative learning into 5E inquiry learning model on interpersonal skills of high school students
No full textEnhancing Disturbance Rejection of PID Controllers for DC Joint Motors of Trajectory Tracking Robots Using Disturbance Observer
Get PDFIn this paper, disturbance rejection of DC motor PID trajectory control systems is enhanced for independent joint control of robot arms. The concept of disturbance observer is invoked to propose a linear auxiliary control that augments existing PID controllers. The design of the auxiliary control is developed using a state space approach rather than transfer function approaches commonly employed in many existing designs derived from the concept of disturbance observer. This provides new insight and leads to a compact design requiring only two design parameters. While many of the existing DC motor trajectory control systems assume the availability of current feedback from a motor coil, the proposed auxiliary control does not. This can highly facilitate its applications in the lacking situation. Realizing that the stability of the resulting control systems could be inconvenient to assert due to increased system dimension resulting from incorporating disturbance observer, compact criteria for asserting robust stability using readily available results is given explicitly. To evaluate the capability of the auxiliary control for disturbance rejection, experimental results on a DC joint motor of an articulated robot arm are given. In presence of smooth and abrupt loading variations due to gravity, it appears that the tracking error of the enhanced system can be approximately 67% of that of the unenhanced system. This result is consistent in all three rounds of experiments
Wave Iterative Computation for Fractal Microstrip Patch Antenna
No full textAbstractThis paper presents an analysis of fractal microstrip patch antenna using new wave iterative computation (WIC) that is a full electromagnetic wave analysis. The wave iterative simulation based on wave propagation and iterative method is created on graphical user interface (GUI) of MATLAB software. The proposed fractal microstrip patch antenna is simulated by developed simulation program and measurement using network analyzer. The analyzed result using wave iterative computation was successfully in comparing with results of measurement and classical simulation tools
Catalytic activities of titania-supported nickel for carbon-dioxide methanation
Get PDFTitania-supported nickel catalysts (3, 6, 12 and 20 wt% Ni/TiO2) were prepared by a sol-gel method. The results showed that the CO2 conversion increased with increasing Ni content and 20 wt% Ni/TiO2 exhibited the highest CO2 conversion and CH4 yield. The results on XRD and EXAFS revealed unit cell expansion and lattice distortion, which indicated that Ni2+ was incorporated into the TiO2 lattice. Upon increasing the Ni content, the NiO phase was observed. The oxidation states of nickel and titanium were analyzed to be +2 and +4, respectively for fresh catalysts. After pretreatment by H-2, Ni2+ was converted to Ni-0 and this electronic state remained unchanged during the course of methanation while Ti4+ was kept unaltered for fresh catalysts and those during the reaction. The addition of Ni led to the formation of oxygen vacancy and NiO phase which might act as adsorption sites for CO2 and H-2, respectively. (C) 2020 Elsevier Ltd. All rights reserved
