Room-temperature multiferroic properties of Co-doped KNbO3 ceramics

KNb_0.95Co_0.05O₃ (KN–Co) ceramic was prepared via a solid-state reaction method, and the effect of cobalt dopant on the structural, electric, and magnetic properties was studied. The KN–Co ceramic with polycrystalline perovskite structure exhibited ferromagnetic and ferroelectric properties simultaneously at room temperature, and the coupling of them was confirmed by a large magnetocapacitance effect (about 13%) near the Curie temperature. The possible causes for the magnetism and magnetoelectric properties are discussed.     

Dynamic release process of pollutants during suspended sediment transport in aquatic system

Pollutants release is highly consistent with suspended sediment concentration （SSC） in water column, especially during re-suspension and transport events. The present research focuses on pollutant dynamic release from re-suspended sediment, especially the vertical distribution relationship between them. The sediment erosion experiments on a series of uniform flow are conducted in a circulate flume. Reactive tracer （phosphorus） is used as the contaminant in fine-grained sediments to identify the release characteristic length and time. Experimental results show that the flow condition near-bed depends on the sediment surface roughness. The region with high turbulent intensities corresponds to a high concentration sediment layer. In addition, the SSC decreases with the distance, water depth, and particle grain size. The sediment in a smaller grain size takes much more time to reach equilibrium concentration. Total phosphorus （TP） concentration changes along the water depth as SSC in the initial re-suspension stage, appearing in two obvious concentration regimes： the upper low-concentration layer and the high-concentration near-bottom layer. This layered phenomenon remains for about 3 hours until SSC distri- bution tends to be uniform. Longitudinal desorption plays an important role in long-way transport to reduce the amount of suspended sediment in water column.     

一种CO2的矿化封存新方法

针对目前CO2矿化封存的研究现状,提出了一种新的CO2矿化封存方法:利用CO2和NH3反应生成三聚氰酸固体,并考察了温度、压力、反应物配比及有无催化剂对三聚氰酸收率的影响。当反应条件为在250℃,22MPa,NH3与CO2反应配比为1∶1.4,反应8h时,最高收率可达到68.3%。此项技术能够与现在工业成熟的富氧燃烧技术联用,实现对CO2的永久性封存,具有经济效益。     

Analysis of cooperative and competitive spectrum sharing for heterogeneous networks based on differential dynamics model

The heterogeneous networks belonging to different service providers form a coalition system for maximizing the profit, where they may either compete or cooperate with each other. In this paper, we introduce the Lokta–Volterra model, a differential dynamics model, to build the competitive and cooperative mechanisms of heterogeneous networks. It considers the natural growth rate of the network itself and competitive and cooperative effects among networks. Then, according to the ordinary differential principle, the stability of the proposed model and its equilibrium points are analyzed. And finally, system performances are evaluated by Vensim that is used for developing, analyzing, and packaging dynamic feedback models. Analysis and simulation results show that the natural growth rate of the network cannot increase its profit, but effective cooperative mechanism among heterogeneous networks can increase the profit of each network. Copyright © 2013 John Wiley & Sons, Ltd.