Progress and trends in hydrate based desalination(HBD) technology:A review

The shortage of freshwater boosts the development of seawater desalination technology. As a novel method, the hydrate based desalination technology has been put forward for decades and achieved considerable development in the past years. This review focuses on the experimental progress at the aspects of the hydrate former choice, formation promotion and ion removal efficiency and conceptive innovation of hydrate separation and energy utilization. It should be noted that gaseous hydrate former with low formation pressure and insoluble liquid hydrate former are worthy for further study. Besides, the water migration caused by propane deserves to be investigated much more deeply for the potential value of wide application. Moreover, the utilization proposal of LNG cold energy brings more possibility of commercial application. In a word, the hydrate based desalination technology is hopefully an environment friendly, low-cost and widely used desalination technology in the near future.

Metastable state of gas hydrate during decomposition: A novel phenomenon

Natural gas hydrates are solid compounds with cage-like structures formed by gas and water.An intriguing phenomenon that gas hydrates can dissociate at a low rate below the ice freezing point has been viewed as the metastability of hydrate.The mechanisms of hydrate metastability have been widely studied,and many mechanisms were proposed involving the self-preservation effect,supercooled water-gas-hydrate metastable equilibrium,and supersaturated liquid-gas-hydrate system etc.The metastable state of hydrate could be of crucial significance in the kinetics of hydrate formation and decomposition,heat and mass transfer during gas production processes,and the application of hydrate-based technique involving desalination,energy storage and transportation,and gas separation and sequestration.Few researches have systematically considered this phenomenon,and its mechanism remains unclear.In this work,various mechanisms and hypothesis explaining the metastable state of gas hydrates were introduced and discussed.Further studies are still required to reveal the intrinsic nature of this metastable state of gas hydrate,and this work could give some implications on the existing theory and current status of relevant efforts.

A review of vehicle speed control strategies

Currently,traffic problems in urban road traffic environments remain severe,traffic pollution and congestion have not been effectively improved,and traffic accidents are still frequent.Traditional traffic signal control methods have little effect on these problems.With the continuous improvement of communication technology and network connections,vehicle speed guidance provides a new idea for solving the above problems and has gradually become a popular topic in academic research.However,its generalization has shortcomings.Therefore,this paper summarizes the research on vehicle speed control strategies in urban road environments and provides suggestions for future research.In this paper,we summarize the existing research in four parts.First,we categorize existing research based on vehicle type.Second,the vehicle speed guidance problem is divided according to the problem research scene.Third,we summarize the existing literature regarding vehicle speed.Finally,we summarize the methods used for speed guidance.Through an analysis of the existing literature,it is concluded that there is a deficiency in the existing research,and suggestions for the future of vehicle speed guidance research are suggested.