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.     

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     

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.     

Action Patterns Probing for Dynamic Service Composition in Home Network

The concept of a smart home has been discussed in recent years. The major purpose is to make life more convenient, safe, and fun in various areas, including home automation, security, entertainment, and so on. In order to automate the interactions between the home users and devices or even between devices, the prediction of the home user’s actions and the integration of devices are very important. The UPnP Device Architecture defines the protocols for communication between the UPnP control point and devices. Exploiting UPnP techniques, home users can easily control intelligent devices through the control point. However, UPnP devices lack a composition mechanism to complete a novel application or value-added service.In this paper, an action patterns probing algorithm is proposed. We propose a dynamic service composition system which coordinates the primitive UPnP services at home. We can predict the action and the data flow with satisfactory accuracy. At first, we define data type ontology for UPnP devices to describe their service interfaces. Afterwards, the interface matching mechanism is employed to construct a service graph that describes which services can be composed together. And we have to analyze the record of user’s actions by using the service graph. Finally, we can find the devices which can be composed and worked together in common use. These devices can be composed dynamically by user’s habits and can be automated by our mechanism.     

Morphology of and surface modification by TiO2 deposits on a porous ceramic substrate

We investigate the morphology of and surface modification by titanium dioxide (TiO₂) deposits on porous ceramic substrates placed in a horizontal, tubular, hot-wall, atmospheric pressure chemical vapor deposition (CVD) reactor with titanium tetraisoperoxide (TTIP) as the precursor. The TiO₂ particles are produced from TTIP through two routes: first by thermal decomposition which then kicks off hydrolysis. The deposit characteristics is found to be location dependent. Those at the reactor entrance and exit are different from that within the reactor. Within the reactor, the deposit characteristics is further found to depend strongly on the deposition temperature (T_d) and is almost independent of the flow-rate and concentration of the reactant. With a T_d of about 380 °C, the deposited TiO₂ forms a forest-like structure with poor adhesivity to the substrate and results in an insignificant pore size reduction for the substrate. If T_d drops down to about 300 °C, the deposited TiO₂ forms a rock-packing structure with good adhesivity to the substrate and can reduce the pore size of the substrate from about 1–2 m down to about 64 nm. At both the reactor entrance and exit, the deposited TiO₂ are loosely-packed spherical particles of average diameter of 140–400 nm. A theory, based on whether or not the reaction is gas-phase or surface dominated, is proposed to explain the dramatic effect of T_d.     

Superior Stability and Emission Quantum Yield (23% ± 3%) of Single‐Layer 2D Tin Perovskite TEA2SnI4 via Thiocyanate Passivation

Tin‐based perovskite, which exhibits narrower bandgap and comparable photophysical properties to its lead analogs, is one of the most forward‐looking lead‐free semiconductor materials. However, the poor oxidative stability of tin perovskite hinders the development toward practical application. In this work, the effect of pseudohalide anions on the stability and emission properties of single‐layer 2D tin perovskite nanoplates with chemical formula TEA₂SnI₄ (TEA = 2‐thiophene‐ethylammonium) is reported. The results reveal that ammonium thiocyanate (NH₄SCN) is the most effective additive in enhancing the stability and photoluminescence quantum yield of 2D TEA₂SnI₄ (23 ± 3%). X‐Ray photoelectron spectroscopic investigations on the thiocyanate passivated TEA₂SnI₄ nanoplate show less than a 1% increase of Sn⁴⁺ signal upon 30 min exposure to air under ambient conditions (298 K, humidity ≈70%). Furthermore, no noticeable decrease in emission intensity of the nanoplate is observed after 20 h in air. The SCN^‐ passivation during the growth stage of TEA₂SnI₄ is proposed to play a crucial role in preventing the oxidation of Sn²⁺ and hence boosts both stability and photoluminescence yield of tin perovskite nanoplates.