Optimal navigation for characterizing the role of the nodes in complex networks

In this paper, we explore how the approach of optimal navigation (Cajueiro (2009) [33]) can be used to evaluate the centrality of a node and to characterize its role in a network. Using the subway network of Boston and the London rapid transit rail as proxies for complex networks, we show that the centrality measures inherited from the approach of optimal navigation may be considered if one desires to evaluate the centrality of the nodes using other pieces of information beyond the geometric properties of the network. Furthermore, evaluating the correlations between these inherited measures and classical measures of centralities such as the degree of a node and the characteristic path length of a node, we have found two classes of results. While for the London rapid transit rail, these inherited measures can be easily explained by these classical measures of centrality, for the Boston underground transportation system we have found nontrivial results.     

An effective method to improve the robustness of small-world networks under attack

In this study, the robustness of small-world networks to three types of attack is investigated. Global efficiency is introduced as the network coefficient to measure the robustness of a small-world network. The simulation results prove that an increase in rewiring probability or average degree can enhance the robustness of the small-world network under all three types of attack. The effectiveness of simultaneously increasing both rewiring probability and average degree is also studied, and the combined increase is found to significantly improve the robustness of the small-world network.Furthermore, the combined effect of rewiring probability and average degree on network robustness is shown to be several times greater than that of rewiring probability or average degree individually. This means that small-world networks with a relatively high rewiring probability and average degree have advantages both in network communications and in good robustness to attacks. Therefore, simultaneously increasing rewiring probability and average degree is an effective method of constructing realistic networks. Consequently, the proposed method is useful to construct efficient and robust networks in a realistic scenario.     

The diminishment of specific heat and surface tension of coolant droplet in a dropwise evaporation process: A novel methodology to enhance the heat transfer rate

The rate of dropwise evaporation is significantly altered by additives, such as benzene, n-hexane and acetone in water. These additives change some of the thermal and physical properties of the coolants, which have significant impact on various parameters that controls the droplet evaporative cooling, such as sensible, heat extraction period, droplet momentum and contact area. The open literature does not reveal the effects of the aforesaid additives on the dropwise evaporation. Therefore, in the current work, an attempt has been made to investigate the effects of above-mentioned additives on dropwise evaporation rate and reveal the mechanism involved. The droplet evaporative cooling experiments are conducted on a 2 mm thick AISI 304 steel plate (10 × 10 mm). The result shows that with increment in benzene and n-hexane concentration in water, the evaporation time significantly reduces. This is attributed to the decreasing surface tension, specific heat and contact angle. However, in case of acetone, the reduction in evaporation time is achieved only up to a concentration of 300 ppm, beyond which the evaporation time increases. This is because of the significant consumption of time in recoiling of the droplet. In addition to the above, the mechanism for the aforesaid enhancement process is tried to reveal by developing the models. For the validation of the developed equations, experimental results are compared with the numerically computed data. The comparison discloses that the developed model is quite accurate and shows insignificant variation from the experimental results. R² and RMSE are also calculated for both the developed models and based on minimum recommended RMSE; the best model is also suggested.     

多针-网电极离子风激励器推力与推功比的实验研究

本文搭建了一种无摩擦气垫悬浮测试平台测量了19针和31针-网电极离子风激励器产生的推力特性, 为多针-网电极离子风激励器作为新型动力源提供动力控制方法. 通过研究多针-网间隙、针-针间距、针尖曲率半径和电晕电压电流对离子风激励器推力特性的影响, 提出了在低功耗下产生较大推力的方法, 改善离子风激励器对低功耗与大推力的需求不能同时满足的现状. 关键词： 多针-网电极 离子风 推力 推功比     

快速应对电网闪对EAST低温系统影响研究

EAST氦低温系统是EAST(Experimental Advanced Super-conducting Tokamak)先进超导托卡马克实验装置重要子系统之一;EAST氦低温系统是高能耗能系统,拥有7台氦压缩机(4台低压缩机,3台高压缩机),总功率达到1.4 MW左右,由于EAST实验是连续运行(每次在120天以上),中间不能有停机、停电等事故,否则实验无法正常运行。其供电稳定性是个大问题,对供电系统、变电站的要求都很高;然而在实验期间由于一些非人为因素,还是出现几次"电网闪"跳电事故,低温系统压缩机部分或全部停机、氦透平膨胀机全停、冷却水泵系统全停、真空泵系统全停等事故。若事故处理不当会导致丢气、管道压力过高、液氦容器爆炸、损坏磁体等严重后果。文中给出了EAST实验期间出现电网闪的事故时进行相应处理步骤与一些快速应对的操作经验。