Novel alkaline earth silicate sealing glass for SOFC: Part I. The effect of nickel oxide on the thermal and mechanical properties

This is a two-part study of a novel Sr–Ca–Ni–Y–B silicate sealing glass for solid oxide fuel cells (SOFC). In this paper (Part I), the effect of NiO on glass forming, thermal, and mechanical properties was studied with two different approaches: glass making and composite glass. In the following paper (Part II), sealing and interfacial microstructure of candidate composite glass with 10 vol.% NiO will be addressed. In Part I, higher NiO content in the glass resulted in precipitation during the glass making process, and the sintered powder compacts of these glasses showed extensive macro- and micro-cracks. Coefficient of thermal expansion (CTE) showed large decrease for glass with higher NiO contents. On the other hand, glass-based composites showed no fracture even with NiO content as high as 15 vol.%. The CTE of the composite glass, which increased with increasing NiO content (consistent with the rule of mixtures prediction), could be adjusted to match the CTE of SOFC components. Phase characterization by XRD identified phases of YBO₃ and NiO in the glass, which were likely responsible for the poor mechanical and thermal properties for the glass making approach.     

Effect of Annealing Environment on the Crack Healing and Mechanical Behavior of Silicon Carbide-Reinforced Alumina Nanocomposites

The crack healing and strength behavior of an alumina-silicon carbide (Al₂O₃-SiC) nanocomposite (Al₂O₃+ 5 vol% 0.2 μm SiC particles) has been studied, as a function of the crack size and the annealing environment. Results show that annealing treatments can significantly increase the indentation strength. The annealing atmosphere has a profound influence on the extent of crack healing and the degree of strength recovery. Annealing in argon results in a strength increase of 50%, whereas annealing in air yields a three-fold improvement in the indentation strength. Scanning electron microscopic observation has shown that healing of indentation cracks occurs in both environments, with the greater degree of healing occurring during annealing in air. Implications of the findings to the strengthening mechanism in Al₂O₃ (SiC) nanocomposites will be discussed.     

Conformational stability of the N-terminal amino acid residues of mutated recombinant pigeon liver malic enzymes

Pigeon liver malic enzyme has an N-terminal amino acid sequence of Met- Lys-Lys-Gly-Tyr-Glu-Val-Leu-Arg-. Our previous results indicated that the N-terminus of the enzyme is located at or near the enzyme's active center involved in Mn(II)-L-malate binding and is also near to the subunits' interface. In the present study, the conformational stability of the various deletion (delta) and substitution mutants at Lys2/Lys3 of the enzyme was investigated with chemical and thermal sensitivities. The lysine residue at position 2 or 3 seems to be crucial for the correct active site conformation, probably through an ion-pairing with Glu6. Deletion at Lys2 or Lys3, delta(K2/K3), and the double mutant K(2,3)E were much less stable than the wild-type enzyme towards chemical denaturation. Kinetic analysis of the thermal inactivation at 58 degrees C of the recombinant enzymes indicated that mutation at position 3 to alanine (K3A) endows the protein with extra stability compared with the wild-type enzyme. K3A is also stable towards chemical denaturation. The concentration of urea that causes half unfolding, [urea]0.5, for K3A is 3.25 M compared with 2.54 M for the wild-type enzyme. The K3A mutant of malic enzyme might therefore have potential practical applications.      

Genetic algorithms for communications network design - an empiricalstudy of the factors that influence performance

We explore the use of GAs for solving a network optimization problem, the degree-constrained minimum spanning tree problem. We also examine the impact of encoding, crossover, and mutation on the performance of the GA. A specialized repair heuristic is used to improve performance. An experimental design with 48 cells and ten data points in each cell is used to examine the impact of two encoding methods, three crossover methods, two mutation methods, and four networks of varying node sizes. Two performance measures, solution quality and computation time, are used to evaluate the performance. The results obtained indicate that encoding has the greatest effect on solution quality, followed by mutation and crossover. Among the various options, the combination of determinant encoding, exchange mutation, and uniform crossover more often provides better results for solution quality than other combinations. For computation time, the combination of determinant encoding, exchange mutation, and one-point crossover provides better results     

Impact of Channel Dangling Bonds on Reliability Characteristics of Flash Memory on Poly-Si Thin Films

In this letter, we fabricated the poly-Si-oxide-nitride-oxide-silicon (SONOS)-type Flash memories on polycrystalline-silicon thin films and found that dangling bonds presented along the grain boundaries in the channel significantly influence their reliability characteristics in the aspects of charge storage, drain disturbance, and gate disturbance. Employing a powerful defect passivation technique, i.e., NH₃ plasma treatment, the charge storage capability was clearly observed to be remarkably improved. Even so, the hydrogenated polycrystalline-silicon thin-film transistors (poly-Si-TFTs) still suffered from serious drain and gate disturbances, which exhibited behaviors that are quite specific and undoubtedly distinct from those observed in the conventional SONOS-type memories on single crystalline substrates     

深圳大剧院改造设计

深圳大剧院是深圳市上世纪80年代建设的，是深圳市颇有影响的“八大文化设施”之一，至今一直是深圳文化演出交流的最重要的场所，已成为深圳城市记忆的一部分，为深圳的文化交流传播做出了杰出的贡献。     

Stripping efficiency and lifetime of carbon foils

Charge-exchange injection by means of carbon foils is a widely used method in accelerators. This paper discusses two critical issues concerning the use of carbon foils: efficiency and lifetime. An energy scaling of stripping efficiency was suggested and compared with measurements. Several factors that determine the foil lifetime—energy deposition, heating, stress and buckling—were studied by using the simulation codes MARS and ANSYS.     

Considerations for an Efficient Mobile Workforce

Support for mobile workers is an important component of an enterprise's overall IT infrastructure. The rapid evolutions in both wireless broadband and handheld device technologies demand a set of guidelines that provide maximum user benefit while maintaining a manageable support model. This article describes what to consider when evaluating handheld devices for corporate standardization.     

Polynomial time algorithms for multicast network code construction

The famous max-flow min-cut theorem states that a source node s can send information through a network (V, E) to a sink node t at a rate determined by the min-cut separating s and t. Recently, it has been shown that this rate can also be achieved for multicasting to several sinks provided that the intermediate nodes are allowed to re-encode the information they receive. We demonstrate examples of networks where the achievable rates obtained by coding at intermediate nodes are arbitrarily larger than if coding is not allowed. We give deterministic polynomial time algorithms and even faster randomized algorithms for designing linear codes for directed acyclic graphs with edges of unit capacity. We extend these algorithms to integer capacities and to codes that are tolerant to edge failures.