We investigate the inter-well coupling of multiple graphene quantum well structures consisting of graphenesuperlattices with different periodic potentials.The general form of the eigenlevel equation for the bound stat...We investigate the inter-well coupling of multiple graphene quantum well structures consisting of graphenesuperlattices with different periodic potentials.The general form of the eigenlevel equation for the bound states of thequantum well is expressed in terms of the transfer matrix elements.It is found that the electronic transmission exhibitsresonant tunneling peaks at the eigenlevels of the bound states and shifts to the higher energy with increasing the incidentangle.If there are N coupled quantum wells,the resonant modes have N-fold splitting.The peaks of resonant tunnelingcan be controlled by modulating the graphene barriers.展开更多
For the multipath fading on electromagnetic waves of wireless communication in the confined areas,the rectangular tunnel cooperative communication system was established based on the multimode channel model and the ch...For the multipath fading on electromagnetic waves of wireless communication in the confined areas,the rectangular tunnel cooperative communication system was established based on the multimode channel model and the channel capacity formula derivation was obtained.On the optimal criterion of the channel capacity,the power allocation methods of both amplifying and forwarding(AF) and decoding and forwarding(DF) cooperative communication systems were proposed in the limitation of the total power to maximize the channel capacity.The mode selection methods of single input single output(SISO) and single input multiple output(SIMO) models in the rectangular tunnel,through which the higher channel capacity can be obtained,were put forward as well.The theoretical analysis and simulation comparison show that,channel capacity of the wireless communication system in the rectangular tunnel can be effectively enhanced through the cooperative technology;channel capacity of the rectangular tunnel under complicated conditions is maximized through the proposed power allocation methods,and the optimal cooperative mode of the channel capacity can be chosen according to the cooperative mode selection methods given in the paper.展开更多
为研究三模式掘进机使用TBM模式在全断面岩层中的施工技术,以广州地铁7号线二期萝岗站—水西站盾构区间工程为研究背景,分别从出渣方式、掘进参数控制、刀具管理和稳定器应用4个方面对三模式掘进机TBM模式施工技术进行总结。结果表明:1...为研究三模式掘进机使用TBM模式在全断面岩层中的施工技术,以广州地铁7号线二期萝岗站—水西站盾构区间工程为研究背景,分别从出渣方式、掘进参数控制、刀具管理和稳定器应用4个方面对三模式掘进机TBM模式施工技术进行总结。结果表明:1)本工程中三模式掘进机使用镶齿滚刀施工,相对光面滚刀的消耗更少,刀盘转矩更低;2)三模式掘进机TBM模式采用泥浆循环和螺旋输送机双通道出渣,可显著降低泥浆管堵塞的概率,提高出渣效率;3)三模式掘进机在前盾、中盾安装稳定器和撑靴,可保证全断面硬岩地层中掘进盾体不发生滚动,同时增强盾体稳定性;4)在全断面岩层中采用三模式掘进机TBM模式开挖隧道,刀盘转速为3.0 r/min,总推力约15000 k N,转矩可控制在1300 k N·m,推进速度为8~12 mm/min。展开更多
基金Supported by the National Natural Science Foundation of China under Grant No. 10832005the Program for Changjiang Scholars and Innovative Research Team in University under Grant No. IRT0730+1 种基金Program for International S & T Cooperation Program of China under Grant No. 2009DFA02320Doctoral Research Foundation of Nanchang University under Grant No. 300715
文摘We investigate the inter-well coupling of multiple graphene quantum well structures consisting of graphenesuperlattices with different periodic potentials.The general form of the eigenlevel equation for the bound states of thequantum well is expressed in terms of the transfer matrix elements.It is found that the electronic transmission exhibitsresonant tunneling peaks at the eigenlevels of the bound states and shifts to the higher energy with increasing the incidentangle.If there are N coupled quantum wells,the resonant modes have N-fold splitting.The peaks of resonant tunnelingcan be controlled by modulating the graphene barriers.
基金financial supports provided by the National Natural Science Foundation of China (No.51274202)the Fundamental Research Funds for the Central Universities (No.2013RC11)+3 种基金the Science and Technology Achievements Transformation Project of Jiangsu Province (No.BA2012068)the Natural Science Foundation of Jiangsu Province (Nos.BK20130199 and BK20131124)Ceeusro Prospective Joint Research Project of Jiangsu Province (No.BY2014028-01)Great Cultivating Special Project at China University of Mining and Technology (No.2014ZDPY16)
文摘For the multipath fading on electromagnetic waves of wireless communication in the confined areas,the rectangular tunnel cooperative communication system was established based on the multimode channel model and the channel capacity formula derivation was obtained.On the optimal criterion of the channel capacity,the power allocation methods of both amplifying and forwarding(AF) and decoding and forwarding(DF) cooperative communication systems were proposed in the limitation of the total power to maximize the channel capacity.The mode selection methods of single input single output(SISO) and single input multiple output(SIMO) models in the rectangular tunnel,through which the higher channel capacity can be obtained,were put forward as well.The theoretical analysis and simulation comparison show that,channel capacity of the wireless communication system in the rectangular tunnel can be effectively enhanced through the cooperative technology;channel capacity of the rectangular tunnel under complicated conditions is maximized through the proposed power allocation methods,and the optimal cooperative mode of the channel capacity can be chosen according to the cooperative mode selection methods given in the paper.
文摘为研究三模式掘进机使用TBM模式在全断面岩层中的施工技术,以广州地铁7号线二期萝岗站—水西站盾构区间工程为研究背景,分别从出渣方式、掘进参数控制、刀具管理和稳定器应用4个方面对三模式掘进机TBM模式施工技术进行总结。结果表明:1)本工程中三模式掘进机使用镶齿滚刀施工,相对光面滚刀的消耗更少,刀盘转矩更低;2)三模式掘进机TBM模式采用泥浆循环和螺旋输送机双通道出渣,可显著降低泥浆管堵塞的概率,提高出渣效率;3)三模式掘进机在前盾、中盾安装稳定器和撑靴,可保证全断面硬岩地层中掘进盾体不发生滚动,同时增强盾体稳定性;4)在全断面岩层中采用三模式掘进机TBM模式开挖隧道,刀盘转速为3.0 r/min,总推力约15000 k N,转矩可控制在1300 k N·m,推进速度为8~12 mm/min。
