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Photogating is an effective strategy to modulate the channel conductance of the device with light-induced gate field or voltage, thereby improving the performance of optoelectronic devices. In this work, to overcome the long response time and low photoresponse of one-dimensional ZnO, a MoS2-on-ZnO photogating vertical heterojunction photodetector is design and constructed. Herein, the ZnO nanowire with high carrier mobility can response ultraviolet light and supply a high-speed carrier transport channel, while the MoS2flake as a photogating layer can response with visible light and transfer photogenerated electrons into the ZnO nanowire to adjust its conductivity. Thus, the irradiation of visible light is equivalent to applying a photo-induced gate voltage on the ZnO nanowire. In addition, the photogenerated electrons will not transmit through the MoS2with low carrier mobility, so that not only the visible light response of the photodetector can be realized, but also its ultraviolet light response is able to be improved. Under ultraviolet light irradiation, the photoresponsivity of the photodetector can be reached to 273 A W−1and the response speed is less than 24 ms. More important, based on this unique heterojunction structure, MoS2-on-ZnO photodetector also illustrates an excellent visible light response with a high photoresponsivity (74 A W−1) and fast response speed (< 24 ms) due to the photogating effect. This work not only paves the way to design high-performance photodetectors with high photoresponsivity and fast response speed, but also provide a promising approach to improve the performance of optoelectronic devices using photogating effect.

Molecular dynamics (MD) simulations of a subtilisin-like serine protease VPR from the psychrophilic marine bacterium Vibrio sp. PA-44and its mesophilic homologue, proteinase K (PRK), have been performed for 20 ns at four different temperatures (300, 373, 473, and 573 K). The comparative analyses of MD trajectories reveal that at almost all temperatures, VPR exhibits greater structural fluctuations/deviations, more unstable regular secondary structural elements, and higher global flexibility than PRK. Although these two proteases follow similar unfolding pathways at high temperatures, VPR initiates unfolding at a lower temperature and unfolds faster at the same high temperatures than PRK. These observations collectively indicate that VPR is less stable and more heat-labile than PRK. Analyses of the structural/geometrical properties reveal that, when compared to PRK, VPR has larger radius of gyration (Rg), less intramolecular contacts and hydrogen bonds (HBs), more protein-solvent HBs, and smaller burial of nonpolar area and larger exposure of polar area. These suggest that the increased flexibility of VPR would be most likely caused by its reduced intramolecular interactions and more favourable protein-solvent interactions arising from the larger exposure of the polar area, whereas the enhanced stability of PRK could be ascribed to its increased intramolecular interactions arising from the better optimized hydrophobicity. The factors responsible for the significant differences in local flexibility between these two proteases were also analyzed and ascertained. This study provides insights into molecular basis of thermostability of homologous serine proteases adapted to different temperatures.

Due to IGBT open-circuit fault of CRH2 EMU’s traction inverter, a method of its fault diagnosis with the three-phase current signals as detection objects is conducted. By applying the wavelet analysis, three-phase current signals are decomposed for four times. With the coefficients of each layer obtained, the energy values of layers are calculated as well as the vectors corresponding to failure modes. According to the vectors regarded as input and the expected output, a BP neural network is established. Through training the network, the parameters of network can be defined. In addition, to test and evaluate the performance of network, certain noise is added to the three-phase current signals. Simulation results show it is feasible for the fault diagnosis of traction inverter.

Research on the lightweight issue of DC-link is an important direction in modern AC drive electric locomotive. Canceling LC filter circuit is an important way to achieve the goal of lightweight. Therefore, this paper focuses on single-phase pulse rectifier without LC filter circuit. The generation mechanism of DC voltage ripple and network-side current harmonics in grid-side converter is derived. Then, aiming to eliminate the current harmonics, the N-order notch filter and PR controller are introduced to the double-loops controller. The loop of voltage outer controller with N-order notch filter can filter out the ripple of DC-side voltage effectively without affecting the dynamic performance of the controller system. Meanwhile, the loop of current inner controller with PR controller can achieve zero steady-state error control to both the fundamental and harmonic current, and can suppress the low order harmonics in the line current effectively. Analysis shows that replacing the original L2C2 filter circuit with software controller is feasible. Finally, the validity and effectiveness of the proposed scheme are verified in computer simulation.

The calculation model of motor operating on asymmetric rotor was defined taking a traction squirrel-cage induction motor in Electric Multiple Units (EMU) as sample. Based on the basic principle of numerical analysis, magnetic field in the motor and current in the bar were calculated for both normal motor and broken-bar motor by using the Jmag software, and both the magnetic field variation and current variation in the bar were summed up. According to the EMU’s special control methods, the motor with two broken bars was simulated at different work point, and the characteristic component variation was presented. The works in this paper lay the foundation of diagnosis method for broken rotor bar fault, especially for traction motor in EMU.

Over the past years, synthesis of pyrrole-imidazole (Py-Im) polyamides has been achieved by solution-phase and solid-phase methods. Comparing with solution-phase synthesis, the solid-phase synthesis has showed great superiority in various aspects. The solid-phase synthesis is a rapid, effective, energy-saving and environment-friendly method, which has been widely used in the synthesis of pyrrole-imidazole polyamides. Many complicated polyamides can be obtained quickly and effectively through this method. By far, the application of the solid-phase synthesis for Py-Im polyamides has made rapid development. Resin as the main carrier, a key substance in solid phase synthesis, consists of two parts: polymer (macromolecular resin) and linking chain (linker). To date, there are many kinds of resins applied in the solid phase synthesis, such as PAM resin, Wang resin, Oxime resin and Clear resin, and so on. In this article, we will focus on the elaboration about the basic principle and application of the four kinds of resins mentioned above in solid-phase synthesis of polyamides. This provides an important reference for development of polyamides.

Aiming at the difficulties to establish dynamic models of industrial robots, a novel fuzzy PID controller based on product strategy was presented. Membership degrees was determined according to position error and error change. Meanwhile, parameters of the fuzzy-PID controller would be tuned by the varied factors calculated from the membership degrees based on product strategy. Considering disturbance of friction, feedforward based on Stribeck model was introduced. Compared with traditional PID controller, experiment of manipulator demonstrates better effectiveness and robustness of the controller. The new controller keeps tracking error within 0.4%.

A novel control scheme based on an improved RBF neural network and PID control method is proposed. When used the RBF network in the PID controller, if RBF network provides the parameter to revise PID while it does not have training finished, the controller will oscillated or even to diverge. As the structure is more complex, and the adjustment speed is slower, the improvements are made to the standard RBF neural network trained algorithm. Uses the matrix operation substitute the iterative algorithm, may avoid the above question effectively. Finally, choosing a certain type of PID controller, the improved RBF neural network algorithm is used to design the control law for control command tracking, the simulation results show that the improved RBF neural network algorithm can avoid oscillated and diverge.