The rapid growth of traffic demand and innovation of mobile networks have pushed the current communication infrastructure to provide a tight integration of different wireless technologies. On the one hand, all user connections are expected to be heterogeneous in future networks and thus an intelligent mobility management is essential to satisfy the requirements of lower latency, less power consumptions and last but not least possible uninterrupted ongoing session when a User Equipment (UE) moves across network boundaries. On the other hand, Device-to-Device (D2D) communication as a revolutionary technology to enhance network performance has shown a great potential in dominating future communication market. Consequently, in this paper, we investigate the mobility management problem for D2D communications in heterogeneous networks. We leverage on IEEE 802.21 Media Independent Service (MIS) and propose a new framework, so-called enhanced version of IEEE 802.21 MIS that supports D2D communication (E-MIS-D2D) to enhance D2D mobility experience over heterogeneous networks. The E-MIS-D2D is a network assisted and initiated architecture, in which a load-aware mode selection algorithm is also proposed for selecting the transmission mode between D2D and non-D2D modes. Through extensive simulations, we validate that the proposed method outperforms the existing methods in terms of packet loss ratio, average throughput, latency, bandwidth usage and load rate of eNB.
Iron sulphides with various S-Fe atomic ratios, such as pyrite, iron(III) sulphide, pyrrhotite and troilite, were used as catalysts for coal liquefaction. Catalytic activities were compared on the basis of the temperature of the exothermic peak due to coal hydrogenolysis. Effects of hydrogen sulphide on catalytic activity of iron sulphides were also investigated. It is concluded that:
1.1. The catalytic activity of iron sulphides increases with increasing S-Fe ratio;
2.2. pyrite, with the highest catalytic activity, is converted to pyrrhotite before the onset of exothermic reactions from coal hydrogenolysis, this evidently being the reason for the high catalytic activity;
3.3. the catalytic activity of iron sulphides depends on the coal type;
4.4. the high catalytic activity of pyrite may be due to the creation of fresh pyrite surface during the reaction rather than to the presence of high concentrations of hydrogen sulphide.
Several different biological compounds were found to be effective pretreatment agents for the removal of water from highly humified peat by mechanical pressing. The peat was pressed for 2.5 min at 1.96 MPa. The agents added were polymers or surfactants. Two compounds were particularly effective. The cationic polysaccharide, chitosan, increased the amount of water removed by 60% compared with the control. The surfactant from Bacillus subtilis increased the amount of water removed by 〉 50%. The mechanism of dewatering by the chitosan is shown to be coagulation of the colloidal particles of peat suspended in water. This allows efficient phase separation by pressing. It is suggested that the surfactant improves dewatering by increasing the spreading coefficient between the trapped interstitial water and the peat waxes. 相似文献
