Multilink and AUV-Assisted Energy-Efficient Underwater Emergency Communications

Recent development in wireless communications has provided many reliable solutions to emergency response issues, especially in scenarios with dysfunctional or congested base stations. Prior studies on underwater emergency communications, however, remain under-studied, which poses a need for combining the merits of different underwater communication links (UCLs) and the manipulability of unmanned vehicles. To realize energy-efficient underwater emergency communications, we develop a novel underwater emergency communication network (UECN) assisted by multiple links, including underwater light, acoustic, and radio frequency links, and autonomous underwater vehicles (AUVs) for collecting and transmitting underwater emergency data. First, we determine the optimal emergency response mode for an underwater sensor node (USN) using greedy search and reinforcement learning (RL), so that isolated USNs (I-USNs) can be identified. Second, according to the distribution of I-USNs, we dispatch AUVs to assist I-USNs in data transmission, i.e., jointly optimizing the locations and controls of AUVs to minimize the time for data collection and underwater movement. Finally, an adaptive clustering-based multi-objective evolutionary algorithm is proposed to jointly optimize the number of AUVs and the transmit power of I-USNs, subject to a given set of constraints on transmit power, signal-to-interference-plus-noise ratios (SINRs), outage probabilities, and energy, which achieves the best tradeoff between the maximum emergency response time (ERT) and the total energy consumption (EC). Simulation results indicate that our proposed approach outperforms benchmark schemes in terms of energy efficiency (EE), contributing to underwater emergency communications.Comment: 15 page

Housing development and urbanisation in China

Rapid urbanisation and rising income have led to a strong demand for housing in urban China. However, housing development has been distorted by speculation, income inequality and lack of government support for low-cost houses. In recent years, house prices become so high, making the vast majority of urban residents unable to afford, whereas rich families are able to buy many and leave them vacant. Income inequality is a major cause for rising house prices, which, in turn, exaggerates income inequality further. This vicious relationship has caused social tension between the rich and the poor and unhappiness among the middle- and low-income groups. This paper discusses the factors responsible for the housing bubble in China and recommends appropriate policies to resolve this problem

Dynamic Structure in Four-strategy Game: Theory and Experiment

Game dynamics theory, as a field of science, the consistency of theory and experiment is essential. In the past 10 years, important progress has been made in the merging of the theory and experiment in this field, in which dynamics cycle is the presentation. However, the merging works have not got rid of the constraints of Euclidean two-dimensional cycle so far. This paper uses a classic four-strategy game to study the dynamic structure (non-Euclidean superplane cycle). The consistency is in significant between the three ways: (1) the analytical results from evolutionary dynamics equations, (2) agent-based simulation results from learning models and (3) laboratory results from human subjects game experiments. The consistency suggests that, game dynamic structure could be quantitatively predictable, observable and controllable in general.Comment: game theory; laboratory game experiment; eigenvector; dynamics system theor

Single-file Movement of Ants Stressed by a High Temperature

Single-file movement is a universal pattern in both nature and human society. In this paper, we investigate single-file movement of ants (Camponotus japonicus) driven by a high temperature in a narrow channel. Here, ants were placed in a chamber. The chamber was connected to a narrow channel which was 10 cm long and 0.6 cm wide so that the ants can escape through it one by one. Both chamber and narrow channel were in high temperature environment. In the channel, the random pause was observed due to the characteristic of ants. Moreover, ants were inclined to following the preceding one and trying to overtake it, which is different from the movement in natural investigation. On the other hand, the speed increased with distance headway when the distance headway is less than 0.26 cm, that is less than the body size of an ant. Furthermore, touching phenomenon was observed. When the following ants touched the preceding one, they could reduce speed, stop or move backward. On the contrary, the preceding ants increased their speed. Thus, the touching effect in multiple ants experiment can enhance the evacuation efficiency