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The goal of trajectory planning is to shorten the flight distance as much as possible on the premise of ensuring the safety of UAV in flight. Therefore, the research of trajectory planning has broad prospects and great significance. As the key technology of trajectory planning, optimization algorithm has increasingly become one of the focuses of scholars at home and abroad. The dynamic programming algorithm is characterized by high computational efficiency and global optimization in trajectory planning. In 3D trajectory planning, as the spatial search space expands, the number of grid points increases faster, and time complexity of the dynamic programming algorithm is ${O}({n}^{3}) $ . It often leads to a “Curse of Dimension” phenomenon, which lowers its computational efficiency drastically. To solve this problem, this paper divides the entire planning space into stages based on Bellman’s optimality principle. A dynamic programming-genetic algorithm(DPGA) is proposed by using genetic algorithm(GA) in each stage for optimization, while using dynamic programming algorithm(DP) in global planning. The global optimization ability of the algorithm is verified through convergence analysis. Moreover, based on a series of simulation experiments, it shows that the improved algorithm proposed in this paper is more efficient than the dynamic programming algorithm and genetic algorithm alone in global optimization.

Ionized field strength on the ground level is one of the fundamental electromagnetic environment parameters of ultrahigh voltage direct current (UHVdc) transmission lines. An algorithm of an upstream boundary element method is presented in this paper to calculate the ionized field on the boundary with a high accuracy. The ionized field is generated and measured in an experimental platform with an HV conductor to a grounded cylindrical corona cage. The relations between ionized field strength and applied voltage, conductor position, and conductor diameter are investigated. Calculations show that the relative error of the ionized field on the HV electrode could be reduced to 0.1% when compared with the analytical solution. Ionized field distribution under the typical ±1100 kV UHVdc transmission lines is also analyzed as the application. [ABSTRACT FROM AUTHOR]

Ion mobility is one of fundamental parameters to describe the motion of ions in an electric field and a significant quantity to calculate the ionized field and ion current density of ultrahigh-voltage direct current (UHVDC) power lines. This paper presents a measurement method for atmospheric ion mobilities in a DC corona discharge. An apparatus with coaxial cylindrical electrodes is designed and utilized. A vibrating electric field meter is employed to measure the ionized field of the electrode. Experimental results show that under atmospheric conditions, the average positive and negative ion mobilities are 1.76 × 10−4 and 1.88 × 10−4m2·V−1·s−1, respectively. The proposed method is compared with previous works of others. The impact of fluctuations of the measured ionized field and ion current density on the results of ion mobilities is also analyzed. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

A new fluorescence “turn-on” nanosensor for carbonate determination was reported based on CdSe quantum dots (QDs) modified with thio ligands containing urea groups: N-(5-mercapto-1,3,4-thiadiazol-2-ylcarbamoyl)-2-(o-tolyloxy)acetamide (AASH-CdSe QDs). The AASH-CdSe QDs were prepared through a ligand exchange process and characterized by transmission electron microscopy (TEM), fluorescence spectroscopy, UV-vis spectroscopy and FT-IR spectroscopy. The synthesized AASH-CdSe QDs allowed a selective fluorescence “turn-on” response towards carbonate. Under optimal conditions, the relative fluorescence intensity increases linearly with carbonate concentration in the range 1 × 10−7–1 × 10−4M with a detection limit of 2.3 × 10−8M. A Langmuir-type binding model was highly effective in describing the carbonate concentration dependence of the luminescence intensity of the AASH-CdSe QDs. The possible mechanism was discussed. [ABSTRACT FROM AUTHOR]

Quinoline derivatives were brought into the surface of gold nanoparticles (Au NPs) through click chemistry. The fluorescence was quenched by Au NPs because of electron transfer between Au NPs and quinoline. However, upon addition of Cd(2+) to the quinoline-triazole Au NP solution, it exhibited an effective switch-on fluorescence response, owing to the coordination between quinoline and Cd(2+) which can efficiently block the electron transfer. What's more, the fluorescent sensor can effectively detect Cd(2+) in aqueous solution with a detection limit of 1.0 × 10(-5) M.