Detailed dynamic Solid Oxide Fuel Cell modeling for electrochemical impedance spectra simulation

This paper presents a detailed flexible mathematical model for planar solid oxide fuel cells (SOFCs), which allows the simulation of steady-state performance characteristics, i.e. voltage-current density (V-j) curves, and dynamic operation behavior, with a special capability of simulating electrochemical impedance spectroscopy (EIS). The model is based on physico-chemical governing equations coupled with a detailed multi-component gas diffusion mechanism (Dusty-Gas Model (DGM)) and a multi-step heterogeneous reaction mechanism implicitly accounting for the water-gas-shift (WGS), methane reforming and Boudouard reactions. Spatial discretization can be applied for 1D (button-cell approximation) up to quasi-3D (full size anode supported cell in cross-flow configuration) geometries and is resolved with the finite difference method (FDM). The model is built and implemented on the commercially available modeling and simulations platform gPROMS™. Different fuels based on hydrogen, methane and syngas with inert diluents are run. The model is applied to demonstrate a detailed analysis of the SOFC inherent losses and their attribution to the EIS. This is achieved by means of a step-by-step analysis of the involved transient processes such as gas conversion in the main gas chambers/channels, gas diffusion through the porous electrodes together with the heterogeneous reactions on the nickel catalyst, and the double-layer current within the electrochemical reaction zone. The model is an important tool for analyzing SOFC performance fundamentals as well as for design and optimization of materials’ and operational parameters.     

Comparison of ultra-fast microwave sintering and conventional thermal sintering in manufacturing of anode support solid oxide fuel cell

Ultra-fast microwave sintering in a multi-mode domestic microwave oven with selective susceptor and spacer has been proved to be an effective and facile method in the manufacturing of anode support solid oxide fuel cell (SOFC). Two anode support SOFCs were fabricated by using ultra-fast microwave sintering and conventional thermal sintering techniques, separately. The performances of the two cells were measured and compared in a temperature range of 700-800 °C. The microstructures of the two cells after the measurements were compared qualitatively based on SEM images. FIB-SEM technique was used to reconstruct the 3-D microstructure of both anode and cathode. The quantitative comparison of 3-D reconstructions shows the application potential and the advantages of microwave technique in SOFCs manufacturing.     

In-situ patterned intra-anode triple phase boundary in SOFC electroless anode: An enhancement of electrochemical performance

Co-existence of intra-anode and conventional triple phase boundary (TPB) is reported for the first time in core (YSZ)-shell (Ni) electroless anode cermet. A mathematical model is proposed for determination of intra-anode TPB length and has been validated experimentally. Retention of longer intra-anode TPB even after repeated redox cycling is responsible for relatively lower conductivity degradation of such cermets. Existence of intra-anode TPB in electroless anode results in significant improvement of electrochemical performance. Single cells with electroless anode exhibit a current density of 2.5 A cm⁻² compared to cells with conventional anode (1.7A cm⁻²) at 800 °C, 0.7 V.     

基于结构方程模型的绿色服装购买行为研究

以消费者的绿色服装购买行为作为研究内容,旨在从心理学角度发现绿色服装购买意愿的影响因素,并探讨行为意愿和影响因素之间的关系.以计划行为理论为依据建立理论模型并设计调查问卷,选取北京、上海、大连3所城市的在校大学生作为调研对象,运用结构方程模型方法,借助SPSS17.0和AMOS7.0软件进行数据分析,得出研究结果.研究结果有助于国内外绿色服装的生产经营商了解国内的市场,也在一定程度上丰富了我国在绿色服装消费领域的学术研究.     

百里香酚兰的液液界面电化学研究

用循环伏安法研究了百里香酚兰在水 /硝基苯界面的离子转移行为。根据百里香酚兰在溶液中的离解平衡和电化学性质 ,讨论了界面离子转移机理 ,并计算了转移离子的标准转移电位△ W0 φ0 和标准吉布斯转移能△ W0 G0 。实验所测半波电位△ W0 φ1 /2 —pH曲线与理论公式相符     

Equivalent Homogeneous Variable Depth Beams for Cracked FGM Beams; Compliance Approach

We explore the compliance approach for K _I evaluation of a cracked three point beam (TPB) of functionally graded material (FGM). We suggest an equivalent beam of variable height for cracked FGM beams which includes the homogeneous beam for the linear, quadratic and cubic variations in elastic modulus along the beam span. The efficacy of equivalent beams is demonstrated numerically on a 250 × 41 × 6 mm FGM beam with modulus varying from 210 – 315 GPa under 5000 N load.     

Effect of particle size on the electrochemical corrosion behavior of X70 pipeline steel

In this study, by using a standard quartz replace of sandy soil particles, the effect of soil particle size (0.1–0.25 mm, 0.6–1.0 mm) on the electrochemical corrosion behavior of X70 pipeline steel in sandy soil corrosive environment simulated by 3.5 wt% sodium chloride (NaCl) was investigated through polarization curve and electrochemical impedance spectroscopy (EIS) technology. The results indicated that the polarization resistance of X70 steel decreased with decreasing particle size. For all polarization curves, the right shift of cathodic branch with decreasing particle size, suggesting that the cathode oxygen reduction process is accelerated. The corrosion of X70 steel is controlled by the process of cathode diffusion and oxygen reduction. This can be attributed to the effect of gas/liquid/solid three‐phase boundary (TPB) zone on cathodic process of X70 steel, and the corrosion rate is mainly determined by the cathodic reaction. EIS of X70 steel consisted of two capacitive loops with 7, 60 and 90 days buried corrosion, and the charge transfer resistance of X70 steel increased with increasing particle size.     

Cross-cultural differences in drivers’ speed choice

The aim of the present study was to examine if there are any cross-cultural differences between Swedish and Turkish drivers’ rating of the variables in the theory of planned behaviour (TPB) with regard to complying with the speed limit. A sample of 219 Swedish and 252 Turkish drivers completed a questionnaire including questions based on the theory of planned behaviour (i.e. regarding attitude, subjective norm, perceived behavioural control, intention and behaviour). The results show that country differences in drivers’ intention to comply with the speed limit as well as their self-reported compliance could be explained by differences found in their attitude, subjective norm and perceived behavioural control. Furthermore, drivers who live in a country with fewer road traffic fatalities (i.e. Sweden), compared with drivers who live in a country with more road traffic fatalities (i.e. Turkey), reported a more positive attitude towards complying with the speed limit, a more positive subjective norm, a higher perceived behavioural control, a higher intention and a larger proportion of the time spent complying.     

Exploring Chinese users’ acceptance of instant messaging using the theory of planned behavior,the technology acceptance model,and the flow theory

Instant messaging (IM) is a popular Internet application around the world. In China, the competition in the IM market is very intense and there are over 10 IM products available. We examine the intrinsic and extrinsic motivations that affect Chinese users’ acceptance of IM based on the theory of planned behavior (TPB), the technology acceptance model (TAM), and the flow theory. Results demonstrate that users’ perceived usefulness and perceived enjoyment significantly influence their attitude towards using IM, which in turn impacts their behavioral intention. Furthermore, perceived usefulness, users’ concentration, and two components of the theory of planned behavior (TPB): subjective norm and perceived behavioral control, also have significant impact on the behavioral intention. Users’ intention determines their actual usage behavior.     

Smart TV: are they really smart in interacting with people? Understanding the interactivity of Korean Smart TV

Smart TV (STV), a new digital television service, has been rapidly developing, particularly in Korea. With the conceptual model of interactivity, this study empirically investigates the effects of perceived interactivity on the motivations and attitudes towards STV in Korea. The model is created to validate the relationship of perceived interactivity to performance, attitude and intention. Further, the model examines the mediating roles of perceived interactivity in the effect of performance on attitude towards STV. Empirical evidence supports the mediating role of perceived interactivity. Implications of the findings are discussed in terms of building a theory of interactivity and providing practical insights into developing a user-centred STV interface.