Poly (acridine orange) (PAO) film-modified electrode was prepared by the electrooxidation of Acridine orange on a glassy carbon electrode (GCE) for the detection of hydroquinone in the presence of o-hydroquinone and m-hydroquinone. The electrochemical behavior of hydroquinone on the modified electrode was investigated with respect to different solution acidity, scan rate, and accumulation time. A pair of sharp and well-defined peaks was obtained at 0.45 and 0.42 V [vs. a saturated calomel electrode (SCE)] at the PAO film-modified electrode. The potential difference between this pair of cathodic and anodic peaks was decreased to only 30 mV as compared to the 241 mV that was obtained on the bare glassy carbon electrode (GCE). As to o-hydroquinone and m-hydroquinone, their corresponding oxidation peaks appeared at 0.55 V and 0.89 V (vs. SCE), respectively. The oxidation potential differences between these three isomers enabled the separate detection of hydroquinone. Under the optimum experimental situation, the oxidation peak current of hydroquinone was proportional to the concentration at the range of 6.8 Â 10 27 -9.6 Â 10 25 M. The detection limit was been estimated as 3 Â 10 27 M with 130 s accumulation. This method was applied to the hydroquinone detection in tap water samples.
An identification-free adaptive optimal control based on switching predictive models is proposed for the systems with big inertia, long time delay and multi models. Multi predictive models are set in the identification-free adaptive predictive control, and switched according to the optimal switching instants in control of the switching law along with the system running situations in real time. The switching law is designed based on the most important character parameter of the systems, and the optimal switching instants are computed out with the optimal theory for switched systems. The simulation test results show the proposed method is suitable to the systems, such as superheated steam temperature systems of electric power plants, can provide excellent control performance, improve rejecting disturbance ability and self-adaptability, and has lower demand on the predictive model precision.
Recently, UAV has been widely used in various fields. The attitude estimation of autonomous UAV is an important basis for its autonomous flight mission. The attitude estimation technique based on GNSS is a traditional positioning method. However, it is a challenge to provide a high precision estimation when GNSS signal cannot be used. This paper summarizes the research status of attitude estimation based on vision or other multi-sensors when GNSS signal is not available. And the various improved methods of KF in UAV attitude positioning are introduced. Then the attitude estimation methods of UAV in multi-aircraft cooperative flight are analyzed. In the end, several issues worthy of attention in the further research are proposed. It should contribute to the further research on autonomous UAV navigation.
Keywords-autonomous unmanned aerial vehicle (UAV); attitude estimation; kalman filter (KF)
Authentic assessment is an effective way for promoting the teaching quality in graduate design. The test method is the foundation of authentic assessment. The steps of graduate design of the major of electronic specialty are first introduced. Then the authentic test method of every step in the graduate is discussed. And several noticeable problem of the authentic test method selection in the graduate design of the major of electronic specialty are proposed. It should be helpful for promoting the student's abilities in the graduate design of the major of electronic specialty.
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