Promoting spinel formation and growth for preparation of refractory materials from ferronickel slag

The study provides a method for improving the quality of the refractory material prepared from ferronickel slag by promoting the spinel formation and growth in the slag which was sintered with sintered magnesia and chromium oxide in a broad sintering temperature range from 1200°C to 1500°C. According to the thermodynamic analysis, except for forsterite due to the addition of sintered magnesia, a number of high-melting point spinel phases can also be formed in the presence of chromium oxide and this trend becomes more apparent with increasing sintering temperature, along with declined presence of low-melting point clinopyroxene, mainly enstatite. This expectation was verified by conversion of a part of the original phase of ferronickel slag, olivine, to two main spinel phases, including magnesium aluminate spinel and donathite which was produced by the replacement of nontoxic Cr³⁺ ions with Fe³⁺ ions in the octahedral vacancies of magnesium chromate spinel. The formation and growth of these spinel phases were promoted by elevating temperature from 1200°C to 1500°C, which accelerated the transition of initially generated enstatite to a glassy phase, in favor of densification. The formation and growth of spinel during sintering contributed to high refractoriness and compressive strength of the resulting refractory materials     

Neighbor caching in multi-hop wireless ad hoc networks

We propose a neighbor caching strategy to overcome the overhead of multi-hop wireless communications. Neighbor caching makes a node able to expand its caching storage instantaneously by storing its data in the storage of idle neighbors. We also present the ranking based prediction that selects the most appropriate neighbor which data can be stored in. The ranking based prediction is an adaptive algorithm that adjusts the frequency of neighbor caching and makes neighbor caching flexible according to the idleness of nodes.     

Seismic performance evaluation of staggered wall system structures with middle corridors

In this paper, the seismic performance of reinforced concrete (RC) staggered wall structures with middle corridor was evaluated. To this end, 6‐, 12‐ and 18‐storey structural models were designed and were analyzed to investigate the seismic load‐resisting capacity. The response modification factors were computed based on the overstrength and the ductility capacities obtained from pushover curves. The effect of a few retrofit schemes on the enhancement of strength and ductility was also investigated. The pushover analysis results showed that the response modification factors ranged between about 4.0 and 6.0 with the average value around 5.0. When the bending rigidity of the link beams increased up to 100%, the overall overstrength increased by only about 25%. When the rebar ratio of the link beams was increased by 50%, the overstrength increased by about 40%. The replacement of the RC link beams with steel box beams resulted in superior performance of the structures with reduced beam depth. The displacement time histories of the model structures subjected to the earthquake ground motions scaled to the design seismic load showed that the maximum interstorey drifts were well below the limit state specified in the design code. Based on the analysis results, it was concluded that the staggered wall systems with a middle corridor had enough capacity to resist the design seismic load. Copyright © 2012 John Wiley & Sons, Ltd.     

Seismic retrofit of structures using steel honeycomb dampers

The purpose of this paper is to investigate the seismic performance of a honeycomb shaped steel hysteretic damper applied to seismic retrofit or strengthening of a structure. The formulas for the initial stiffness and yield strength of a damper unit were derived based on the cell wall bending model, and the results were compared with those obtained from finite element analysis. Bilinear model of the honeycomb damper was developed based on the nonlinear force-displacement relationship obtained from finite element analysis. The honeycomb dampers were applied for seismic retrofit of a 15-story apartment building designed without considering seismic load and for seismic design of a 3-story moment frame designed with reduced seismic load. The analysis results showed that the honeycomb dampers were effective in the enhancement of seismic-load resisting capacity of the model structures.     

Density-controlled, solution-based growth of ZnO nanorod arrays via layer-by-layer polymer thin films for enhanced field emission

A simple, scalable, and cost-effective technique for controlling the growth density of ZnO nanorod arrays based on a layer-by-layer polyelectrolyte polymer film is demonstrated. The ZnO nanorods were synthesized using a low temperature (T = 90?°C), solution-based method. The density-control technique utilizes a polymer thin film pre-coated on the substrate to control the mass transport of the reactant to the substrate. The density-controlled arrays were investigated as potential field emission candidates. The field emission results revealed that an emitter density of 7?nanorods?μm(-2) and a tapered nanorod morphology generated a high field enhancement factor of 5884. This novel technique shows promise for applications in flat panel display technology.     

Schema-aware XPath filtering on XML document streams

The XML stream filtering is gaining widespread attention from the research community in recent years. There have been many efforts to improve the performance of the XML filtering system by utilizing XML schema information. In this paper, we design and implement an XML stream filtering system, SFilter, which uses DTD or XML schema information for improving the performance. We propose the simplification and two kinds of optimization, one is static and the other is dynamic optimization. The Simplification and static optimization transform the XPath queries to make automata as an index structure for the filtering. The dynamic optimization are done in runtime at the filtering time. We developed five kinds of static optimization and two kinds of dynamic optimization. We present the novel filtering algorithm for the resulting transformed XPath queries and runtime optimizing. The experimental result shows that our system filters the XML streams efficiently.     

Non-redundant web services composition based on a two-phase algorithm

Recently, there has been growing interest in developing web services composition search systems. Current solutions have the drawback of including redundant web services in the results. In this paper, we proposed a non-redundant web services composition search system called NRC, which is based on a two-phase algorithm. In the NRC system, the Link Index is built over web services according to their connectivity. In the forward phase, the candidate compositions are efficiently found by searching the Link Index. In the backward phase, the candidate compositions decomposed into several non-redundant web services compositions by using the concept of tokens. Results of experiments involving data sets with different characteristics show the performance benefits of the NRC techniques in comparison to state-of-the-art composition approaches.     

Solubility of Nitrogen in High Manganese Steel (HMnS) Melts: Interaction Parameter between Mn and N

Nitrogen solubility in Fe-Mn melts was measured using a N₂ bubbling and sampling method at temperatures from 1823 K to 1923 K (1550 °C to 1650 °C) for manganese content to about 25 mass pct. The effect of temperature on the nitrogen solubility was well described based on the thermodynamic behavior of Fe-Mn system. Furthermore, the interaction parameter between Mn and N was evaluated as a function of temperature. The present results can be used in thermodynamic analyses of the formation of nitride compounds such as AlN or TiN in high manganese steel melts for example, transformation induced plasticity (TRIP) and twin induced plasticity (TWIP) aided steels as well as high Mn-N alloyed stainless steels.     

Multifunctional hybrid polymer nanocomposites for automotive-battery packaging

Global sales of new electric vehicles (EV) already passed a million units last year. Lithium-ion battery packs are composed of cells and assembly of modules. Nevertheless, the development of light-weighted with high oxygen and moisture barrierability remains one of the untouched issues in battery technology. This study aimed to fabricate multifunctional hybrid nanocomposites for barrier films for Li-ion battery packs on electric vehicles applications. The synthesized carbon supported MgO nanoparticles (hereafter referred to as CSMO) were dispersed in high density polyethylene (HDPE) polymer to satisfy several requirements for EV battery packs. The loading amount of MgO was achieved up to 22 wt % of carbon, and the size distribution was in the range of 50 to 100 nm. The hybrid nanocomposites were characterized by water-vapor transmission rate (WVTR), various spectroscopic methods, thermo-gravimetric analysis and elemental analysis. Mechanical properties were also tested. The extremely low WVTR value of CSMO/HDPE composites below 0.5 mgm⁻² day⁻¹ is the lowest value among any other gas barrier films reported in the literature. Suitable mechanical properties were also achieved. The newly proposed multifunctional hybrid nanocomposites would be very promising for barrier films on automotive packaging applications.