High-Temperature Performance Analysis of AlGaN/GaN Polarization Doped Field Effect Transistors Based on the Quasi-Multi-Channel Model

We report on the temperature-dependent dc performance of A1GaN/GaN polarization doped field effect transistors （PolFETs）. The rough decrements of drain current and transeonductance with the operation temperature are observed. Compared with the conventional HFETs, the drain current drop of the PolFET is smaller. The transeonductance drop of PolFETs at different gate biases shows different temperature dependences. From the aspect of the unique carrier behaviors of graded AlGaN/GaN heterostructure, we propose a quasi-multi-channel model to investigate the physics behind the temperature-dependent performance of AlGaN/GaN PolFETs.

THE RELATIONSHIPS BETWEEN THE POLARIZING FORCE OF CATIONS AND THE ELECTROPHILIC CHARACTER AND CATALYTIC PERFORMANCES OF PROMOTED Pt-Al_2O_3 CATALYST

The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method（CHRM）and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.

A high performance tunable optical filter based on cascaded polarization interference filter

A new kind of tunable optical filter is proposed for DWDM optical communication application. It is based on cascaded polarization interference filter (PIF). The period and bandpass width of each PIF are decided by its optical path difference between o-ray and e-ray (OPDOE). When their OPDOEs are proportionately designed, the tuning range and bandpass width depend on OPDOE in the first and the last PIF, respectively. The tuning range, bandpass width and crosstalk are independent each other. The crosstalk is related to the OPDOE ratios among PIFs and can be suppressed by designing the PIF's OPDOE. A set of OPDOE is suggested that are l1, 2 × l1, 22 ×l1, 23 ×l1, 24 ×l1, ..., 2N-4 × l1, 15 × 2N-7 ×l1, 10 × 2N-6 × l1 and 2N-2 ×l1 from the first to the last. This suggested OPDOEs can yield -50-dB crosstalk for any tuning range and bandpass width. The insert loss is less than 1 dB. As its loose alignment requirement, there is no limitation on cascaded PIF number. When 11 PIFs are cascaded, it can achieve 170-nm tuning range, -50-dB crosstalk, bandpass width applicable to 25-GHz channel spacing and 1 dB insert loss.

Three-dimensional multiphase modeling of a proton exchange membrane electrolysis cell with a new interdigitated-jet hole flow field

The flow field structure on the bipolar plate significantly affects the performance of the proton exchange membrane electrolysis cell(PEMEC).This paper proposes a new interdigitated-jet hole flow field(JHFF)design to improve the uniformities of liquid saturation,temperature,and current density distributions.The common single-path serpentine flow field(SSFF)and interdigitated flow field(IFF)are used as comparative references to constitute three PEMEC cases.An advanced numerical model has been established to simulate the performance of the PEMEC using CFD software.The results show that,due to the perpendicular mainstream and the pressure difference,the JHFF enhances the mass and heat transfer inside the porous electrode by introducing strong forced convection,which promotes gas removal underneath the ribs and cooling.Compared with the comparative flow fields,the uniformities of liquid saturation,temperature,and current density distributions by using the JHFF at the anode side are increased by 19.1%,53.2%,and 40.4%,respectively.Further,mainly owing to the largest conductive area,the PEMEC with the JHFF has superior polarization performance,which is 8.05%higher than the PEMEC with the SSFF.