To investigate the effects of matching characteristics of tandem cascade on the performance and flow at large angle of attack, the unsteady numerical simulation has been implemented. The influences of different turnin...To investigate the effects of matching characteristics of tandem cascade on the performance and flow at large angle of attack, the unsteady numerical simulation has been implemented. The influences of different turning angle ratio(TR) and chord length ratio(CR) of two blades and the relative angle of attack of rear blade(Delta) are analyzed. The numerical results indicated that the tandem cascade can obtain overall performance improvement including higher static pressure ratio and lower total pressure loss with the matching parameters in the range of TR=3～5, CR=0.5～1.2, and Delta=-15°～-5°. The separation on the front blade has more prominent impact than that on the rear blade, so the performance improvement of tandem cascade is significantly dependent on the reduction of front-blade separation and loss. Regarding the rear blade, the gap injection effect can periodically control the separation. Temporal and spatial analysis of the flow field shows that the optimal-performance cases generally have much smaller wake loss for both two blades, but the unsteady characteristics of the wake loss is more apparent than that of the poor performance cases.展开更多
Structure and design are proposed for a kind of novel polymer Mach-Zehnder electro-optic(EO)switch using side-coupled M series-cascaded EO microrings.Formulations are proposed to analyze its switching characteristics....Structure and design are proposed for a kind of novel polymer Mach-Zehnder electro-optic(EO)switch using side-coupled M series-cascaded EO microrings.Formulations are proposed to analyze its switching characteristics.The dependences of the device’s performances on M are thoroughly analyzed and concluded.As the increase of M from 2 to 10,the switching voltages for the 9 devices are as low as 0.84 V,0.82 V,0.52 V,0.5 V,0.37 V,0.36 V,0.29 V,0.28 V and 0.24 V,respectively;whereas the crosstalks under bar state are within-20.79--6.53 d B and those under cross state are within-20.36--5.29 d B.The analysis results indicate that a smaller M is preferred for dropping the insertion loss and crosstalk,and a larger M should be selected to increase the optical bandwidth and minimize the switching energy.Generally,due to low switching voltage,the proposed device shows potential applications in optical networks-on-chip.展开更多
Relocation is an important event in the lives of several social insects whereby all colony members have to be transferred to a new nest when conditions in the old nest become unfavorable. In the current study, network...Relocation is an important event in the lives of several social insects whereby all colony members have to be transferred to a new nest when conditions in the old nest become unfavorable. In the current study, network tools were used to examine the organization of this goal-oriented task in the Indian queenless ant Diacamma indicum Which relocate their colonies by means of tandem running. Individual ants were used as nodes and tandem runs as directed edges to construct unweighted networks. Network parameters were characterized in control relocations （CRs） and in relocations where the node with the highest outdegree, that is, the Maximum tandem leader （Max TL） was experimentally removed. These were then compared to 1） randomized networks, 2） simu- lated networks in which Max TL was removed, and 3） simulated networks with removal of a random leader. Not only was there complete recovery of the task, but the manner in which it was organized when Max TL was removed was comparable to CRs. The results obtained from our empirical study were significantly different from the results predicted by simulations of leader removal. At an individual level, the Max TL had a significantly higher outdegree than expected by chance alone and in her absence the substitute Max TL did comparable work. In addition, the position of the Max TL in the pathway of information flow was conserved in control and experimentally manipulated conditions. Understanding the organization of this critical event as more than the sum of individual interactions using network parameters allows us to appreciate the dynamic response of groups to perturbations.展开更多
基金supported by the National Natural Science Foundation of China (No. 51506179, No. 11772146)the Aeronautics Power Foundation (No. 6141B090303)
文摘To investigate the effects of matching characteristics of tandem cascade on the performance and flow at large angle of attack, the unsteady numerical simulation has been implemented. The influences of different turning angle ratio(TR) and chord length ratio(CR) of two blades and the relative angle of attack of rear blade(Delta) are analyzed. The numerical results indicated that the tandem cascade can obtain overall performance improvement including higher static pressure ratio and lower total pressure loss with the matching parameters in the range of TR=3～5, CR=0.5～1.2, and Delta=-15°～-5°. The separation on the front blade has more prominent impact than that on the rear blade, so the performance improvement of tandem cascade is significantly dependent on the reduction of front-blade separation and loss. Regarding the rear blade, the gap injection effect can periodically control the separation. Temporal and spatial analysis of the flow field shows that the optimal-performance cases generally have much smaller wake loss for both two blades, but the unsteady characteristics of the wake loss is more apparent than that of the poor performance cases.
基金supported by the National Natural Science Foundation of China(Nos.61107021,61177027 and 61077074)the Ministry of Education of China(Nos.20110061120052 and 20120061130008)the Science and Technology Department of Jilin Province of China(No.20130522161JH)
文摘Structure and design are proposed for a kind of novel polymer Mach-Zehnder electro-optic(EO)switch using side-coupled M series-cascaded EO microrings.Formulations are proposed to analyze its switching characteristics.The dependences of the device’s performances on M are thoroughly analyzed and concluded.As the increase of M from 2 to 10,the switching voltages for the 9 devices are as low as 0.84 V,0.82 V,0.52 V,0.5 V,0.37 V,0.36 V,0.29 V,0.28 V and 0.24 V,respectively;whereas the crosstalks under bar state are within-20.79--6.53 d B and those under cross state are within-20.36--5.29 d B.The analysis results indicate that a smaller M is preferred for dropping the insertion loss and crosstalk,and a larger M should be selected to increase the optical bandwidth and minimize the switching energy.Generally,due to low switching voltage,the proposed device shows potential applications in optical networks-on-chip.
文摘Relocation is an important event in the lives of several social insects whereby all colony members have to be transferred to a new nest when conditions in the old nest become unfavorable. In the current study, network tools were used to examine the organization of this goal-oriented task in the Indian queenless ant Diacamma indicum Which relocate their colonies by means of tandem running. Individual ants were used as nodes and tandem runs as directed edges to construct unweighted networks. Network parameters were characterized in control relocations （CRs） and in relocations where the node with the highest outdegree, that is, the Maximum tandem leader （Max TL） was experimentally removed. These were then compared to 1） randomized networks, 2） simu- lated networks in which Max TL was removed, and 3） simulated networks with removal of a random leader. Not only was there complete recovery of the task, but the manner in which it was organized when Max TL was removed was comparable to CRs. The results obtained from our empirical study were significantly different from the results predicted by simulations of leader removal. At an individual level, the Max TL had a significantly higher outdegree than expected by chance alone and in her absence the substitute Max TL did comparable work. In addition, the position of the Max TL in the pathway of information flow was conserved in control and experimentally manipulated conditions. Understanding the organization of this critical event as more than the sum of individual interactions using network parameters allows us to appreciate the dynamic response of groups to perturbations.
