Mingzhe Hu

Sintering behavior and dielectric properties of Bi3+-substituted Nd(Zn0.5Ti0.5)O3 microwave ceramics

The sintering behavior and dielectric properties of Bi3+-substituted Nd(Zn0.5Ti0.5)O3 (abbreviated as NZT) microwave ceramics (Nd1−xBix)(Zn0.5Ti0.5)O3 (0 ≤ x ≤ 0.15) (abbreviated as NBZT) are investigated. XRD results reveal the formation of single perovskite solid solutions for x ≤ 0.05 samples. For x > 0.05 samples, pyrochlore phase begins to segregate from the perovskite phase and its volume fraction increases with x. B-site Zn2+/Ti4+ 1:1 long range order (LRO) is detected by Raman Spectroscopy. The degree of LRO varies as a function of sintering conditions and chemical composition. The microwave dielectric properties of the composition are measured. By substituting Bi3+ for Nd3+, the temperature coefficient of resonant frequency (τf) tunes toward zero, however, the microwave quality factor, (Qf) deteriorates. For x = 0.03, τf reaches a minimum value of −18.9ppm/∘C with relative permittivity of er = 48.2 and Qf = 1430GHz, respectively. The effect of Bi-doping on the Qf value is discussed.

The Research on Three-phase Photovoltaic Grid-connected Inverters Control Strategy Based on MPPT

This paper develops successfully SVPWM voltage vector tracking current control model for three-phase grid-connected inverter and a novel current scheme under two phase synchronous rotating frame is presented, which is using grid feed forward controller. Considering the efficiency of photovoltaic modules, using an improved maximum power tracking algorithm. The simulation results show that the inverter has high output power factor and photovoltaic system has good dynamic performance and tracking result. Introduction The key technology of Photovoltaic (pv) grid power generation system researched mainly the utilization of photovoltaic arrays and the control strategy of grid inverter, which the control system directly affected the whole system performance. Firstly, it generally needed to adopt MPPT algorithm to improve the utilization efficiency of pv, the variable step-size perturbation observation method had better tracking speed and accuracy than traditional perturbation observation method. Secondly, output voltage waveform quality was an important indicator of a inverter, The voltage vector tracking current control of fixed switching frequency SVPWM is studied. Compared with the SPWM control [1,2], which the voltage utilization of DC side is higher and dynamic performance is better. At the same time, it is convenient to eliminate the steady-state error of AC in the rotating coordinate system. As the emergence of high-speed digital signal processor (DSP), for the pv inverter digital control provided a convenient, proposing a three-phase SVPWM inverter based on double closed-loop control. The Mathematical Model of PV Grid Inverter The topology of three Phase Grid-Connected inverter, as shown in Fig. 1. Using the Kirchhoffs law, we could get the model of each phase voltage loop of the inverter in three-phase stationary coordinate system[3]. As shown in equation (1).

Design and simulation of a spoof SPPs microwave filter

In the present paper a novel kind of spoof SPPs microwave filter is designed and simulated on computer. The filter is composed of four sections, where in the third section, parallel and symmetrically arranged corrugated metallic strip is the spoof SPPs transmission line, which is coupled with each other, and in which, periodically arranged rectangular slot is designed to fulfill the spoof SPPs effect. The transmission and reflection properties of the spoof SPPs filter in microwave frequency region is elaborately investigated by FDTD method. Through adjusting the geometrical dimensions of the plasmonic coupling structure as well as the rectangular slots, the bandwidth and suppression characteristics of the filter can be precisely controlled and the filter has better resistant ability to space electromagnetic interference.

A band pass microwave filter with planar spoof surface plasmon polaritons structure

In the present paper a band pass microwave filter with spoof surface plasmon polaritions (SPPs) structure is designed and simulated using FDTD method. The filter is composed of four sections, where in the third section, parallel and symmetrically arranged corrugated metallic strip is the spoof SPPs transmission line, in which, periodically arranged rectangular slot is designed to fulfill the spoof SPPs effect. In the fourth section, the spoof SPPs lines are coupled with each other to realize the transmission zero in the up stop band range. The transmission and reflection properties of the spoof SPPs filter in microwave frequency region are elaborately investigated by FDTD method. Through adjusting the geometrical dimensions of the plasmonic coupling structure as well as the rectangular slots structure, the bandwidth and suppression characteristics of the filter can be precisely controlled and the filter has great resistant ability to space electromagnetic interference.

A new spoof surface plasma polaritons band-pass filter with interdigital structure

A new type spoof surface plasma polaritons (SSPPs) band pass filter was devised successfully. The filter possessed three-section structure of composite groove, the co-planar wave guide as the first section, microstrip wave guide as the second section, and SSPPs as the third section. It should be noted that there is a interdigital structure or composite composite groove structure in the first or third section, which are carried out by the simulation on characteristics of upper drag band and bandwidth for band pass filter. These results indicated that the filter had bandwidth between 3.1504GHz and 6.3398GHz during −3dB–0dB, the ripple jitter in the passband being better than 0.8dB, and reflection being less than −10dB. This new type of SSPPs filter will be certain engineering value in the application of microstrip circuit, microwave base station and radar microwave communication system between L band and X band.

Microwave property improvement of Ca[(Li1/3Nb2/3)0.95Zr0.15]O3+δ perovskite by A-site substitution

The crystal structure and microwave dielectric properties of Ca[(Li1/3Nb2/3)0.95Zr0.15]O3+δ ceramic (CLNZ) are tuned by A-site substitution of Sr2+ and Ba2+ ions in the present paper. The tuning effect on the crystal structure is investigated by the X-ray diffraction (XRD) pattern and it illustrates that single phase of orthorhombic perovskite structure is formed, however, minor amount of BaNb2O6-type second phase is also detected in (Ca1−xBax)[(Li1/3Nb2/3)0.95Zr0.15]O3+δ ceramics (CBLNZ) in the range of x ≥ 0.025, while pure perovskite phase is obtained in (Ca1−xSrx)[(Li1/3Nb2/3)0.95Zr0.15]O3+δ ceramics (CSLNZ) in the whole investigation range of 0 ≤ x ≤ 0.2. With the increase of x value, the unit cell volumes of both CBLNZ and CSLNZ perovskites gradually expand, which results in the degradation of the vibration bond strength between the B-site ions and oxygen in the perovskites. The microscopic structure related thermal parameters in CSLNZ and CBLNZ perovskites are analyzed in terms of Clausius–Mossotti...

Research on Electronic Waste Recycling—Liupanshui City as an example

According to the present situation and trend of industrialization of electronic waste at home and abroad, combining the reality of Liupanshui region of electronic waste recycling. This paper studies on the technology and process of electronic waste recycling being basic on the precious metals which recover from the electronic circuit board. Using water elutriation to Prepare blister copper process is simple and the key technology is the waste water solid-liquid separation technology which combines with the research on the hydrometallurgy of chemical method and physical method research. In order to realize the real recycling, zero pollution, zero emission and to receive precious metals which matches with the national standards. As well as to lay a solid foundation for creating Liupanshui circular economy demonstration city and national environmental protection model city.