Synthesis, structural analysis and electrochemical performances of BLSITCFx as new cathode materials for solid oxide fuel cells (SOFC) based on BIT07 electrolyte

BaIn_0.3Ti_0.7O_2.85 (BIT07) is a suitable electrolyte for Solid Oxide Fuel Cell (SOFC) but half cells based on La_0.58Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF) as a cathode material show a degradation of the Area Specific Resistance (ASR) at 700 °C with time. This study deals with the characterization of alternative cathode materials showing a better compatibility with BIT07 than LSCF. A new solid solution, Ba_xLa_0.58(1−x)Sr_0.4(1−x)In_0.3xTi_0.7xCo_0.2(1−x)Fe_0.8(1−x)O_3−δ, with 0 ≤ x ≤ 1, also called BLSITCFx, with in this case x expressed in molar %, derived from BIT07 and LSCF, has been synthesized at 1350 °C in air using BIT07 and LSCF powders. Two compositions, BLSITCF12 and BLSITCF25, have been selected due to their thermal expansion and conductivity properties. Symmetrical half cells based on these two new materials deposited on BIT07 electrolyte have been studied by complex impedance spectroscopy in air versus temperature and time. Their behaviour is comparable to LSCF's, with ASR values never exceeding 0.2 Ωcm² at 700 °C, and moreover their less important Thermal Expansion Coefficient (TEC) mismatch with BIT07 lead to a better mechanical compatibility with time. These new compounds are therefore better candidates than LSCF as cathode materials for SOFC based on BIT07 electrolyte.     

J607RHDQ和LB-65L熔敷金属成分与性能对比

介绍了07Mn Ni Mo DR钢制乙烯球罐工程中所使用的国产焊条和日本进口焊条的建造实例,并对其化学成分、熔敷金属力学性能、扩散氢含量以及焊接试板的力学性能等数据进行分析,得出国产焊条与日本焊条的焊接接头力学性能指标相当,均可满足设计温度为-45~-50℃范围内07Mn Ni Mo DR钢制乙烯球罐的建造要求。     

基于CPLD的数字电压表设计

双积分型ADC具有转换精度高,速度慢的特点,因而被广泛应用于高精度数字仪器仪表中。该设计的主要创新点是以可编程器件（CPLD）为核心,采用积分电路、检零比较器等组成16位ADC,控制部分采用51单片机,能实现自动量程转换。由于采用了CPLD技术,减少了外界干扰和所占空间,而且大大提高了系统的响应时间,提高了数字电压表的性能。     

基于MPC07运动控制卡的步进电机控制系统研究

阐述了MPC07运动控制卡的工作原理和使用方法;分析了利用Visual Basic语言编程实现步进电机的多轴运动控制,具有控制方便、运动可靠和开发简单的特点.     

Cubic Spline Collocation for Volterra Integral Equations

In the standard step-by-step cubic spline collocation method for Volterra integral equations an initial condition is replaced by a not-a-knot boundary condition at the other end of the interval. Such a method is stable in the same region of collocation parameter as in the step-by-step implementation with linear splines. The results about stability and convergence are based on the uniform boundedness of corresponding cubic spline interpolation projections. The numerical tests given at the end completely support the theoretical analysis. Received: January 15, 2002; revised July 27, 2002 Published online: December 19, 2002     

Isolation concepts for efficiently enumerating dense subgraphs

In an undirected graph G=(V,E), a set of k vertices is called c-isolated if it has less than ck outgoing edges. Ito and Iwama [H. Ito, K. Iwama, Enumeration of isolated cliques and pseudo-cliques, ACM Transactions on Algorithms (2008) (in press)] gave an algorithm to enumerate all c-isolated maximal cliques in O(4^cc⁴|E|) time. We extend this to enumerating all maximal c-isolated cliques (which are a superset) and improve the running time bound to O(2.89^cc²|E|), using modifications which also facilitate parallelizing the enumeration. Moreover, we introduce a more restricted and a more general isolation concept and show that both lead to faster enumeration algorithms. Finally, we extend our considerations to s-plexes (a relaxation of the clique notion), providing a W[1]-hardness result when the size of the s-plex is the parameter and a fixed-parameter algorithm for enumerating isolated s-plexes when the parameter describes the degree of isolation.     

A simple approach for robust economic design of control charts

Robust economic control chart designs incorporating robustness with regard to the uncertainty in the cost and process parameters, reported in the literature, fall into two broad categories. One category of robust economic designs considers the uncertainty in the estimates of the cost and process parameters and makes the design suitable to operate well in any scenario arising out of the uncertainty. Other category of robust economic design considers different possible discrete scenarios for a single process and makes the control chart robust to all possible scenarios. The approach suggested for the robust designs for each category is different and somewhat complicated. The present paper proposes a design approach by introducing a simple statistic for the robust economic design problem of a ‘process with multiple scenarios’. SGA has been used in the optimization. The suggested statistic handles the information regarding the relative frequency of occurrence of each scenario of the process for the robust designs.     

On admissible pairs and equivalent feedback—Youla parameterization in iterative learning control

This paper revisits a well-known synthesis problem in iterative learning control, where the objective is to optimize a performance criterion over a class of causal iterations. The approach taken here adopts an infinite-time setting and looks at limit behavior.The first part of the paper considers iterations without current-cycle-feedback (CCF) term. A notion of admissibility is introduced to distinguish between pairs of operators that define a robustly converging iteration and pairs that do not. The set of admissible pairs is partitioned into disjoint equivalence classes. Different members of an equivalence class are shown to correspond to different realizations of a (stabilizing) feedback controller. Conversely, every stabilizing controller is shown to allow for a (non-unique) factorization in terms of admissible pairs. Class representatives are introduced to remove redundancy. The smaller set of representative pairs is shown to have a trivial parameterization that coincides with the Youla parameterization of all stabilizing controllers (stable plant case).The second part of the paper considers the general family of CCF-iterations. Results derived in the non-CCF case carry over, with the exception that the set of equivalent controllers now forms but a subset of all stabilizing controllers. Necessary and sufficient conditions for full generalization are given.     

Approximation of 1/||x−y|| by Exponentials for Wavelet Applications (Short Communication)

We discuss the approximation of by exponentials in order to apply it to the treatmentof 1/||x-y||. In the case of a wavelet basis, one has in addition the vanishing moment property, which allows to add polynomials without increasing the computational effort. This leads to the question whether an approximation of by the sum of a polynomial and an exponential part yields an improvement. We show that indeed the approximation error is remarkably reduced. The improvement depends on the interval on which is approximated.