自动语言辨识的研究方法及发展概述

根据自动语言辨识研究中所采用的识别信息的不同,文章将研究中使用的方法归类为基于声学特征的方法、基于韵律特征的方法、基于音素识剐的方法和基于高层语言信息的方法.通过对这些方法进行分类介绍并结合NIST的评测结果分析,阐述了近十几年来自动语言辨识研究的发展情况,最后对进一步研究中存在的问题和发展趋势进行了分析.     

采用SDC结构的微波宽带平衡放大器及其CAD

微波宽带平衡放大器由于其众多的优点,在许多微波通信设备中发挥着其独特、可靠的作用。解决平衡放大器电路设计的关键在于实现高方向性、紧耦合的3dB定向耦合器部件。本文介绍了一种采用锯齿形级联定向耦合器结构的微波宽带平衡放大器电路,并在电路原理分析的基础上得到了其CAD方法。最后研制了相应的硬件电路,经测试表明电路指标良好,取得了令人可喜的实用成果。     

基于单片机的自整角机转角测量研究

介绍了一种基于单片机的自整角机转角测量方法,该方法省略了自整角机/数字转换器(SDC)和交流激磁电源,直接利用单片机进行激磁和采样来确定自整角机的转角,不仅硬件系统组成简单、满足测量精度,降低系统开发成本,而且,提高了系统的可靠性。本方法已经应用到航空仪表伺服控制系统中。     

固体氧化物燃料电池Ni/SDC阳极材料的制备与表征

采用一种改进的均相共沉淀法一缓冲溶液法合成出NiO-Ce0.8Sm0.2O1.9复合粉体,对其相组成和粒度进行了表征.以NiO-Ce0.8-Sm0.2O1.9复合粉体为原料制备出固体氧化物燃料电池Ni/SDC阳极材料,对其微结构和相关性能进行了测试分析,并与由机械混合NiO-SDC粉体所制备的Ni/SDC材料进行了比较.结果表明,通过缓冲溶液法合成的NiO-SDC粉体具有纳米级粒度,以其制备的Ni/SDC阳极材料比由机械混合粉体所制备Ni/SDC材料的晶粒度和孔隙更为均匀和细小,电导率也更高,且以此为阳极的SOFC单电池表现出更优异的电池性能.     

High conductive (LiNaK)2CO3Ce0.85Sm0.15O2 electrolyte compositions for IT-SOFC applications

Composite electrolytes of lithium, sodium, and potassium carbonate ((LiNaK)₂CO₃), and samarium doped ceria (SDC) have been synthesized and the carbonate content optimized to study conductivity and its performance in intermediate-temperature solid oxide fuel cell (IT-SOFC). Electrolyte compositions of 20, 25, 30, 35, 45 wt% (LiNaK)₂CO₃–SDC are fabricated and the physical and electrochemical characterization is carried out using X-ray diffraction, scanning electron microscopy, electrochemical impedance spectroscope, and current–voltage measurements. The ionic conductivity of (LiNaK)₂CO₃–SDC electrolytes increases with increasing carbonate content. The best ionic conductivity is obtained for 45 wt% (LiNaK)₂CO₃–SDC composite electrolyte (0.72 S cm^?1 at 600 °C) followed by the 35 wt% (LiNaK)₂CO₃–SDC composite electrolyte (0.55 S cm^?1 at 600 °C). The symmetrical cell of the 35 wt% (LiNaK)₂CO₃–SDC composite electrolyte with lanthanum strontium cobalt ferrite (LSCF) electrode in air gives an area specific resistance of 0.155 Ω cm² at 500 °C. The maximum power density of the fuel cell using 35 wt% (LiNaK)₂CO₃–SDC composite electrolyte, composite NiO anode and composite LSCF cathode is found to be 801 mW cm^?2 at 550 °C.     

Catalytic modification of Ni–Sm-doped ceria anodes with copper for direct utilization of dry methane in low-temperature solid oxide fuel cells

A Cu/Ni/Sm-doped ceria (SDC) anode has been designed for direct utilization of dry methane in low-temperature anode-supported solid oxide fuel cells. The anode is prepared by the impregnation method, whereby a small amount of Cu is incorporated into the previously prepared Ni/SDC porous matrix. After reduction, Cu nanoparticles adhere to and are uniformly distributed on the surface of the Ni/SDC matrix. For the resulting Cu/Ni/SDC anode-supported cell, maximum power density of 317 mW cm⁻² is achieved at 600 °C. The power density shows only ∼2% loss after 12-h operation. The results demonstrate that the Cu/Ni/SDC anode effectively suppresses carbon deposition by decreasing the Ni surface area available and the level of carbon monoxide disproportionation. This combination of effects results in very low-power density loss over the operating time.     

Thermally stable current-collecting silver grid coated with ceramic-capping layer for low-temperature solid oxide fuel cells

In an effort to decrease the operating temperature of solid oxide fuel cells (SOFCs), nano-porous thin Pt layers have been used as a cathode material with catalytic activity. Because of porous and thin characteristic of the Pt cathode, however, a large cathode area results in a significant performance deterioration because of the increased sheet resistance of the Pt cathode. In this study, we developed a Ag-patterned grid as a current-collecting layer and a samaria-doped ceria (SDC) oxide-capping layer on the porous Pt cathode to decrease sheet resistance and enhance electrochemical performance. Enhanced electron transportation and thermo-stable behavior of fabricated fuel cells indicated three-fold enhanced peak power density and more than two-fold thermomechanical stability, as per scanning electron microscopy (SEM) and electrochemical analysis results.     

中低温固体氧化物燃料电池的研究现状

中低温燃料电池被认为固体燃料电池中最具发展前景的一种。介绍了发展ILTSOFC的研究发展方向,从电解质、阴极材料和阳极材料等诸方面介绍了研究现状和热点,并对中低温氧化固体燃料电池进行了展望。     

Fabrication and characterization of anode support low-temperature solid oxide fuel cell based on the samaria-doped ceria electrolyte

In this paper anode support was fabricated by tape casting method using SDC-50 wt.% NiO slurry, then printed the Ce_0.8Sm_0.2O_1.9 (SDC) electrolyte on the green piece which is cut out from the dried slurry piece. After at 90 °C drying for 14 h and co-sintered at 1350 °C for 10 h, get the Φ70 mm anode support and electrolyte planar bilayer. Based on the observation of photos and scanning electron microscopy (SEM) indicated that bilayer owns the flat anode support substrate, and the highly dense, crack free electrolyte film which is 12 μm in thickness. Small disks which were cut out from the Φ70 mm bilayer structure electrochemically were examined in a single button-cell mode incorporating a SDC-60 wt.% La_0.5Sr_0.5Co_0.8Fe_0.2O₃ composite cathode. The single cell was tested at 450 °C∼600 °C, an open-circuit voltage (OCV) of 0.94 V and the maximum power density of 797 mV cm⁻² achieved with dry hydrogen as fuel gas and air as oxidant gas at 600 °C.     

智能动力混凝土-低标号自密实混凝土的探索与实践

本文结合我国原材料和混凝土市场的特点,基于巴斯夫自主知识产权的RheoMATRIX外加剂新技术,提出了以C30为代表的低标号自密实混凝土的新概念及解决方案-智能动力混凝土（Smart Dynamic Concrete^TM,SDC）。智能动力混凝土的设计参数：胶凝材料总量低于380kg／m^3,初始流动度600-670mm,1hr的流动度不小于600mm,T50不超过12s,无泌水、离析现象。大量的试验证明,智能动力混凝土在中国市场上具有广泛的推广应用前景。