Thermodynamic optimization of contact melting of phase change material inside a horizontal cylindrical capsule

Finite time thermodynamic analysis is applied to the contact melting process of phase change material inside a horizontal cylindrical capsule. With the minimum entropy generation in given time as the objective function the quadratic nonlinear ordinary differential equation that the optimal melting process should be satisfied is derived. The dimensionless liquid height, melt liquid film thickness, Nusselt number, melting rate, optimal wall temperature and entropy generation are obtained by the numerical method. The optimal results are discussed and compared with the unoptimizable analytical results under the condition of constant wall temperature. It is found that the heat transfer and thermodynamics performance of the optimal melting process is better than that of the melting with constant wall temperature.     

Decentralized coordination of autonomous swarms inspired by chaotic behavior of ants

In this paper, we propose a decentralized coordination algorithm for a group of mobile nodes, called an autonomous swarm, on a finite two-dimensional space, which can efficiently coordinate cooperatively the autonomous swarm to the optimal solution. Our algorithm is inspired by chaotic behavior of a single ant and self-organization behavior of the whole ant colony. To construct this algorithm, we firstly assume that each agent is a nonlinear oscillator presenting the chaotic behavior of a single ant. Then we establish a self-organization mechanism according to the self-organization behavior of the whole ant colony. Moreover, we analyze the convergence of the proposed algorithm. Finally, we experimentally evaluate the performance of our algorithm with the clustering and dispersion operations of a swarm. Comparison results of the proposed algorithm and the gradient-type one are also presented to illustrate the effectiveness of the proposed scheme in approximately global optimization for swarms.     

作物秸秆降解中稀有机酸的萃取回收

作物秸秆有机降解的研究中,有机酸的回收利用是一个非常重要的环节,本研究采用低沸点的乙酸乙酯和高沸点的磷酸三丁酯（TBP）作萃取剂,对作物秸秆有机酸（乙酸,丙酸）降解中不同浓度的稀有机酸溶液（汽提液和洗涤液）用液－液淬取法回收,结果表明：磷酸三丁酯的萃取能力大于乙酸乙酯,同一萃取剂对丙酸的萃取效果比对乙酸好。     

Calculation on the CO2 influences on the structure,stability of (MgO)m (m = 1–6) clusters

ABSTRACT

The concentration of carbon dioxide (CO₂) has a significant influence on the morphology of thermal decomposition products of magnesite. So, structures, stabilities and adsorption mechanisms of (MgO)_m (m?=?1–6) clusters by one or two CO₂ molecules were calculated by the GGA-PW91 method. The results show that the stability of the considered clusters is (MgO)_m(CO₂)₂ clusters > (MgO)_m(CO₂) clusters > (MgO)_m clusters by the average binding energy. Certain low-lying isomers of (MgO)_m(CO₂) and (MgO)_m(CO₂)₂ clusters which have an isolated O atom are deviating from the cluster center which possess higher kinetic activity. (MgO)_m clusters prefer to adsorb a CO₂ molecule, while (MgO)₃(CO₂) clusters prefer to adsorb a CO₂ molecule rather than the neighbors. Magnesite is difficult to transit to (MgCO₃)₂ clusters at room temperature. However, magnesite will spontaneously transit to (MgO)₂ clusters and further transit to MgO crystal which need to adsorb more energy at 700?K.