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Nickel selenide with the single-phase structure has been widely studied as counterelectrode nanomaterials for dye-sensitized solar cells (DSCs). However, the effect mechanism of the crystalline structure on the electrocatalytic activity is still needed to be explored and analyzed in nickel selenide with hybrid structure. Therefore, NiSe/NiSe2 hybrid nanomaterials are synthesized via a simple solvothermal approach in this work. NiSe/NiSe2 counterelectrodes are constructed by spraying NiSe/NiSe2 hybrid nanomaterials onto fluorine-doped tin oxide glass. The hybrid nanostructure of NiSe/NiSe2 counterelectrodes exhibits the more catalytic active sites, strong charge separation, and transfer ability for the reduction of triiodide owing to the well-controlled crystalline structure of nickel selenide. Therefore, the results from electrochemical measurements prove that the electrocatalytic activity of the optimized NiSe/NiSe2 counterelectrode is higher than that of platinum electrode. As a result, the DSC with the optimized NiSe/NiSe2 counterelectrode yields a remarkable photoelectrical conversion efficiency of 7.78%, which is larger than that of the DSC based on platinum electrode (7.09%). Our research work provides the insight into design and construct of nickel selenide counterelectrodes of DSCs.

A distributed energy system (DES) using controlled power electronics converters delivers power to loads, via conventional, as well as a number of renewable, energy sources. However, stability concerns retard the integration of power electronics converters into an existing DES. Therefore, due to the high penetration of power converters, the overall network analysis of DES is becoming increasingly difficult. Impedance-based DES modeling emerged as an effective technique as it reduces the system into source and load subsystems and offers easier analysis of the dynamic interactions between them. These models can be obtained using either analytical calculations, simulations, or experimental measurements. In this work, firstly, a line-to-line current injection technique is used for the measurement of alternating current (AC) impedances. Since it requires repeated injections, a d q -domain impedance measurement methodology based upon a set of independent perturbations and measurements is proposed. The perturbation is injected via a sweep signal which is preprocessed by the digital signal processor (DSP) prior to injection. The d q reference frame is synchronized with the three-phase AC system using a low-bandwidth phase-locked loop (PLL). The close matching of impedance parameters measured in simulation using the proposed approach with those obtained using analytical expressions and the line-to-line current injection technique verifies the effectiveness of the approach. Furthermore, the method was also implemented experimentally, and the close matching of the results with the analytical and simulation results validates the overall modeling and measurement procedure.

LED traffic communication can solve flexible the problem of mobile communication terminal in intelligent traffic communication system, however, the low error rate in the condition of long distance is the key of LED optical communication in the intelligent transportation applications. In order to further improve the performance of LED traffic communication system and reduce the error rate, the spread spectrum technology with strong anti-interference capability and pulse position modulation (PPM) technology with high power and high efficiency are applied into the system. The simulation results show that we can get the relationship between signal to noise ratio (SNR) and error rate in the condition of Gaussian white noise, the spread spectrum technology combined with PPM can get lower error rate comparing with single PPM, which can improve the communication quality and distance in the LED traffic communication system.

An ultra-thin metamaterial triple bandpass filter with high quality-factors is presented. This proposed structure consists of a periodic array of three concentric circle ring resonators at the top layer and a metallic mesh at the bottom layer, which are separated by a thin dielectric substrate. The investigations on the distribution of the electromagnetic field and surface current are made for explaining the filtering mechanism. The structure is also demonstrated to be flexibly and independently tunable of the pass-band resonance frequencies. Moreover, this simple structure with ultra-thin thickness is also a symmetric design which is insensitive to the polarization and incident angles. Experimental measurement of the manufactured sample show good agreement with the numerical simulations. Therefore, such a metamaterial triple bandpass filter is of great importance in some practical applications.

Based on the transverse Ising model and using decoupling approximation to the Fermi-type Green's function, we study the phase transition properties of the epitaxial ferroelectric film with one substrate. A general recursive equation of the ferroelectric thin film with two n-layer materials is obtained, which enables us to study the phase transition properties for any number layers for epitaxial ferroelectric thin film. With the help of this equation, we analyze the effect of the exchange interaction and the transverse field in the phase diagram, the influence to the polarizations and Curie temperature numerically. The results show that epitaxial ferroelectric film are able to induce a strong increase or decrease of Curie temperature to different exchange interactions and transverse fields within the epitaxial film layers. The theoretical results are in reasonable accordance with experimental data of different ferroelectric thin film.

Research shows that traditional end-to-end delay upper bound in wireless sensor network (WSN) is pessimistic. Thus based on network calculus, this paper presents a network model with the arrival curve regulated by the leaky bucket and rate-latency service curve, and derivates an improved deterministic upper bound of end-to-end delay in WSN by improving the output bound of a flow traversing a node. Due to the stricter output bound, the delay upper bound derived in the paper is simpler and more accurate, which is useful for topology control and routing protocol design in delay-guaranteed WSN in order to improve the quality of service. Numerical results show that the paper's delay bounds are improved well, which are much tighter than traditional delay bounds.

In order to enhance the autonomous navigation ability of multiple mobile robots, a tabu search based leader follower flocking algorithm is proposed to overcome the local minima problem and realize the autonomous navigation in unknown obstacle environments. Leader robot is capable of avoiding obstacles and seeking goal by tracking virtual sub goals generated by tabu search algorithm, follower robots which are led by leader robot keep formation and cohesion under the control of flocking algorithm for motion control. The whole flocking system is able to go through obstacle environments and reach the preset goal without collision and separation. A simulation example in complex environment validates the correctness and effectiveness of the proposed algorithm.

A novel flexible metamaterial narrow-band-pass filter is designed and proved to be reliable by both numerical simulations and experimental measurements. The unit cell of the designed structure consists of circle ring resonators on top of a thin dielectric layer backed by a metallic mesh. The investigations on the distribution of the surface current and magnetic field as well as the analysis of the equivalent circuit model reveal that the magnetic resonance response between layers induced by the reverse surface current contributes to the high quality factor band-pass property. Importantly, it is a flexible design with a tunable resonance frequency by just changing the radius of the circle rings and can also be easily extended to have the multi-band-pass property. Moreover, this simplified structure with low duty cycle and ultra-thin thickness is also a symmetric design which is insensitive to the polarization and incident angles. Therefore, such a metamaterial narrow-band-pass filter is of great importance in the practical applications such as filtering and radar stealth, and especially for the conformal structure applications in the infrared and optical window area.

Based on the two-level hierarchy control model, the fuzzy controller is designed aiming at different control parameters. The principle and design process of offset fuzzy controller are described in detail. The accuracy and comprehensiveness of designed fuzzy controller has been increased significantly by adding the change rate of traffic parameters to the input interface. The result of the simulation of actual line road proves that this method can reduce the average time of delay effectively.

Automotive electromagnetic environments are analysed. In view of the reliability designs, for instance, in the entirety, hardware and software, etc., the paper focuses on a description of the reliability measures of automotive microcomputer control systems.