A New Family of Proton‐Conducting Electrolytes for Reversible Solid Oxide Cells: BaHfxCe0.8−xY0.1Yb0.1O3−δ

Reversible solid oxide cells based on ceramic proton conductors have potential to be the most efficient system for large‐scale energy storage. The performance and long‐term durability of these systems, however, are often limited by the ionic conductivity or stability of the proton‐conducting electrolyte. Here new family of solid oxide electrolytes, BaHf_xCe_0.8?xY_0.1Yb_0.1O_3?δ (BHCYYb), which demonstrate a superior ionic conductivity to stability trade‐off than the state‐of‐the‐art proton conductors, BaZr_xCe_0.8?xY_0.1Yb_0.1O_3?δ (BZCYYb), at similar Zr/Hf concentrations, as confirmed by thermogravimetric analysis, Raman, and X‐ray diffraction analysis of samples over 500 h of testing are reported. The increase in performance is revealed through thermodynamic arguments and first‐principle calculations. In addition, lab scale full cells are fabricated, demonstrating high peak power densities of 1.1, 1.4, and 1.6 W cm^?2 at 600, 650, and 700 °C, respectively. Round‐trip efficiencies for steam electrolysis at 1 A cm^?2 are 78%, 72%, and 62% at 700, 650, and 600 °C, respectively. Finally, CO₂? H₂O electrolysis is carried out for over 700 h with no degradation.     

通过仿真确保信号完整性设计

PowerPC处理器能帮助实现快速灵活的可编程嵌入式平台设计.Virtex-4 FX平台利用集成于双PowerPC处理器的创新辅助处理器单元(APU)控制器,支持新的硬件加速应用.FX APU控制器又大大改善了软件算法的执行,提高了FPGA资源可用性.本文将介绍使用Xilinx/Ansoft 10Gbps背板设计套件确保互连性能.     

使用基于模型的设计进行虚拟测试

本文分析了系统设计中常用的末期测试可能造成的成本及设计周期的增加,进而提出了基于模型的设计方法,通过在系统设计中并行进行虚拟测试,大大缩短设计周期,降低设计成本.     

Multiplexing of Fiber-Optic Long-Period Grating-Based Interferometric Sensors

Two long-period gratings (LPGs) fabricated in series in an optical fiber form a Mach-Zehnder interferometer, producing a sinusoidal channelled spectrum within the characteristic LPG attenuation bands, which has the appearance of an interference fringe pattern. The phase of the fringes is sensitive to changes in the surrounding environmental parameters, such as refractive index. Fabrication of a number of identical cascaded LPG pairs with different separations produces independent fringe patterns of different frequencies within the attenuation bands. The application of basic Fourier techniques to analyze the transmission spectrum allows the phase of each fringe pattern to be determined independently, facilitating the differentiation of external effects acting on each interferometer.     

Integrated Q-switched multiple-cavity glass waveguidelaser

A novel Q-switching scheme, using rapid variation of the path difference between the cavities of a multiple-cavity resonator, is described. A thermooptic phase modulator was used to switch the cavity loss of a Y-junction glass waveguide laser between high and low states. Q-switched pulses with durations of 5 μs and peak powers of 70 mW were obtained     

Small signal equivalent circuit for Geiger-mode avalanchephotodiodes

The first small signal equivalent circuit for a Geiger-mode avalanche photodiode (GMAP) is presented. The equivalent circuit is derived from a 20 μm-diameter GMAP with 3 μm virtual guard ring overlap; the photodetector has peak responsivity at 600 nm and a calculated electrical bandwidth of 5.97 GHz     

Amplifying four-wavelength combiner, based on erbium/ytterbium-doped waveguide amplifiers and integrated splitters

We report the successful system demonstration of a four-wavelength integrated-optics amplifying combiner. The arrangement consists of an all-connectorized 4/spl times/1 glass splitter followed by a 4.5-cm-long Er/Yb-doped waveguide amplifier. When injecting 120 mW of 975-nm laser diode pump, we record, in the amplifying section, 11.6 dB of net gain in the single pass configuration and 23 dB in the double pass as well as a noise figure of 4.5 dB. These results show the potentiality of ion-exchange technology for the fabrication of lossless telecommunication devices.     

A Simplified Expression for the Probability of Error for Binary Multichannel Communications

We present a simplified expression for the probability of error, P_e, for binary multichannel communications. The original expression was derived by Proakis in 1968. More recently, Simon and Alouini presented an expression involving the generalised Marcum Q-function. In this letter we present a simplified form of Simon and Alouini's expression. The application of this result to the calculation of performance metrics for communications over fading channels is also discussed.