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Transport Cooperation across Borders:Towards Common Transport Policy in the Western Balkans 预览
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作者 Mate Gjorgjievski 《交通与运输工程:英文版》 2019年第4期171-180,共10页
The implementation of infrastructure projects with cross-border significance,and pursuing a common transport policy in the Western Balkans which supports the regulatory and institutional reforms,have a substantial imp... The implementation of infrastructure projects with cross-border significance,and pursuing a common transport policy in the Western Balkans which supports the regulatory and institutional reforms,have a substantial impact on the regional economies.They contribute to the opening of the regional markets and boosting the intraregional and international trade.For a region which suffered tremendously during the 1990’s and saw brutal abruption of the transport network across the region,leaving fragmented pieces of what used to be a nearly single transport system,the coordination of investments for large transport infrastructure projects and policies which facilitates such investments,is of utmost importance.The transport policy and investment coordination on regional level is conducted under the South East Europe Transport Observatory(SEETO),aiming to promote development of the multimodal SEETO Comprehensive Network,which now forms part of the Trans-European Transport Networks(TEN-T Comprehensive Network).The paper will firstly focus on the general conditions of the Network and elaborate the methodology and coordination mechanisms for prioritization of regional-scale projects,the investments in which,have reached€10.8 billion in 2007-2011 period.Although significant progress of the network conditions is apparent,the investments needs of the regional transport network are still quite high:€8.6 billion.(source:SEETO).Parallel to the development of the Network,the countries from the region endeavor to carry out measures that transform and modernize their national transport system in line with the EU Transport Policy.The paper will look at these soft/horizontal measures that aim at alleviation of the regulatory and institutional deficiencies,thus bringing added value to the regional transport policy.Finally,the paper will recommend further incentives for transport collaboration across border and actions at regional level which are likely to have greater impact on the transport and border-crossing facilitation as well 展开更多
关键词 Transport infrastructure transport service transport network
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Why Cycling in 2007 Was Faster than Being Driven in 2017 in Tianjin 预览
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作者 John Zacharias Qiang Sheng 《交通与运输工程:英文版》 2019年第1期1-12,共12页
Changes in the road environment of Tianjin were intended to speed up the traffic system and shift bicyclists to the metro,bus and car.The metro system was greatly expanded,along with a modernized bus fleet.App-based t... Changes in the road environment of Tianjin were intended to speed up the traffic system and shift bicyclists to the metro,bus and car.The metro system was greatly expanded,along with a modernized bus fleet.App-based taxi services were also introduced.In 2007,travellers to the central area were intercepted to determine the starting point of their trip and their travel mode.The most time-efficient trips in 2007 were by bicycle(61%).These trips were re-enacted in 2017 using taxi and metro as it was no longer physically possible to replicate most of the original bicycle trips.Trips greater than 5 km in distance were somewhat faster by taxi than they were by bicycle,but overall,travel time by taxi was greater than by the bicycle for those same trips in 2007.A network analysis of road changes provides explanation why longer trips became more efficient while short trips became less efficient.Travel by metro alone was much longer than the other two methods,but the combination of app-based bicycles and metro would render this travel method the most efficient. 展开更多
关键词 TRANSPORT efficiency non-motorized TRANSPORT road infrastructure TAXI hailing service BICYCLE private car
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5G Flexible Optical Transport Networks with Large-Capacity, Low-Latency and High-Efficiency 预览
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作者 Yuefeng Ji Jiawei Zhang +1 位作者 Yuming Xiao Zhen Liu 《中国通信:英文版》 SCIE CSCD 2019年第5期19-32,共14页
The fifth generation(5G) of mobile communications are facing big challenges, due to the proliferation of diversified terminals and unprecedented services such as internet of things(IoT), high-definition videos, virtua... The fifth generation(5G) of mobile communications are facing big challenges, due to the proliferation of diversified terminals and unprecedented services such as internet of things(IoT), high-definition videos, virtual/augmented reality(VR/AR). To accommodate massive connections and astonish mobile traffic, an efficient 5G transport network is required. Optical transport network has been demonstrated to play an important role for carrying 5G radio signals. This paper focuses on the future challenges, recent studies and potential solutions for the 5G flexible optical transport networks with the performances on large-capacity, low-latency and high-efficiency. In addition, we discuss the technology development trends of the 5G transport networks in terms of the optical device, optical transport system, optical switching, and optical networking. Finally, we conclude the paper with the improvement of network intelligence enabled by these technologies to deterministic content delivery over 5G optical transport networks. 展开更多
关键词 5G OPTICAL TRANSPORT NETWORKS OPTICAL devices OPTICAL TRANSPORT system OPTICAL SWITCHING OPTICAL NETWORKING
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The surface current method in gray Dancoff factor calculation 预览
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作者 Omid Safarzadeh 《核技术:英文版》 SCIE CAS CSCD 2019年第6期28-34,共7页
The Dancoff correction is important in the calculation of the effective cross section of resonant isotopes in a heterogeneous system. Although the neutron current method is a simple and straightforward approach to est... The Dancoff correction is important in the calculation of the effective cross section of resonant isotopes in a heterogeneous system. Although the neutron current method is a simple and straightforward approach to estimate the Dancoff factor, its use is limited to the black Dancoff factor. In this paper, we expand the current method used to determine both the black and gray Dancoff factors. The method developed also relies on a neutron transport solver, where a fixed source on a fuel rod surface has an outward direction, a cosine distribution, and a constant shape. The detector is located on the surface of the rods to measure incoming and outgoing currents;therefore, there is no need to calculate the chord length, and the development, validation, and verification of the code can be omitted. The mathematical foundation of the suggested method is derived using the integral transport equation. The effects of the moderator and lattice configuration are followed by a sensitivity analysis of the Dancoff factor for several problems, including pressurized water reactor and cluster fuel assemblies. The maximum and average relative errors of the calculated results are approximately 0.3% and 0.05%, respectively. 展开更多
关键词 BLACK Dancoff GRAY Dancoff INTEGRAL TRANSPORT EQUATION Interface current TRANSPORT SOLVER
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Systematic calibration of drift diffusion model for InGaAs MOSFETs in quasi-ballistic regime
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作者 Shaoyan DI Lei SHEN +4 位作者 Pengying CHANG Kai ZHAO Tiao LU Gang DU Xiaoyan LIU 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第6期122-129,共8页
This paper proposes a systematic procedure to calibrate the parameters of the drift-diffusion(DD) model for a performance evaluation of InG aA s MOSFETs in the quasi-ballistic regime. The simulation results of a deter... This paper proposes a systematic procedure to calibrate the parameters of the drift-diffusion(DD) model for a performance evaluation of InG aA s MOSFETs in the quasi-ballistic regime. The simulation results of a deterministic multi-subband Boltzmann transport equation(BTE) solver serve as the standard.The DD model is calibrated both under low and high electric fields. The electrostatic characteristics, low field mobility model, and high field saturation model are calibrated in proper sequence, and a good agreement among the drive current, carrier distribution, and velocity distribution are achieved between the results of the calibrated DD model and the BTE solver. The proposed calibration procedure can also be employed in devices made of other materials. 展开更多
关键词 DRIFT-DIFFUSION model calibration BOLTZMANN TRANSPORT equation BTE BALLISTIC TRANSPORT high field In GaAs MOSFET
CO2 emission of urban passenger transportation in China from 2000 to 2014 预览
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作者 YUAN Rui-Qiang TAO Xin YANG Xiang-Long 《气候变化研究进展:英文版》 CSCD 2019年第1期59-67,共9页
This study reviewed the urban passenger transportation(UPT)development of seven typical cities in China from 2000 to 2014,estimated the UPT CO2emission,analyzed the structure,and discussed the main factors of UPT CO,e... This study reviewed the urban passenger transportation(UPT)development of seven typical cities in China from 2000 to 2014,estimated the UPT CO2emission,analyzed the structure,and discussed the main factors of UPT CO,emission.Results showed that increases of GDP,population,and UPT scale of the cities have speeded up.The most significant development of UPT is that the growth of private vehicles is greatly faster than that of public transportation.The total and per-capita UPT CO2 emissions both increased.The share of private vehicles emission to total UPT CO2emission has increased,with the share in range of 65%-88%in 2014,exponentially leading to the increases of total and per-capita UPT CO2 emission.Although UPT CO2 emission structure with more share of public transportation would slow down the UPT CO2emission increase,private vehicle CO2 emission is recognized as the dominated driving factor.Contributions of driving factors,such as GDP,population,private vehicle CO2 emissions,to UPT CO2 emission are different among the cities.Private vehicle CO2 emission.is the dominated factor for UPT CO2emission in Beijing and Taiyuan.Besides private vehicle CO2emission,GDP also plays an important role in UPT CO2emissions of Chengdu,Shanghai,Guangzhou,and Urumqi.Contributions of private vehicle CO2 emission and GDP to UPT CO2 emission are almost same in Xi'an. 展开更多
关键词 URBAN PASSENGER TRANSPORT CO2 EMISSIONS Low-carbon TRANSPORT China
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Bedload transport from analytical and turbulence phenomenological perspectives 预览
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作者 Subhasish Dey Sk Zeeshan Ali Ellora Padhi 《国际泥沙研究:英文版》 SCIE 2019年第6期509-530,共22页
In this paper,we present the dynamics of bedload transport from two different perspectives.They are the analytical perspective and the turbulence phenomenological perspective.In bedload transport from the analytical p... In this paper,we present the dynamics of bedload transport from two different perspectives.They are the analytical perspective and the turbulence phenomenological perspective.In bedload transport from the analytical perspective,we highlight the systematic advances in the analytical modelling of bedload transport over the decades.These advances are principally classified into three broad foundations,namely,the deterministic foundation,that includes the bed shear stress concept,stream power concept,force balance concept and bedform concept,and the probabilistic foundation and the turbulence phenomenological foundation of bedload transport.The bedload transport from the turbulence phenomenological perspective brings into focus the bedload-induced turbulence phenomenology,including the hydrodynamics of mobile-bed and water-worked bed flows.We also discuss the recent advances in the biofilm-coated bedload transport.Finally,conclusion is drawn,highlighting the major research challenges. 展开更多
关键词 BEDLOAD TRANSPORT FLUVIAL hydraulics Sediment TRANSPORT TURBULENT ow
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Tuning the electronic transport anisotropy in borophene via oxidation strategy
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作者 HE YuanYuan CHENG Na +2 位作者 CHEN Chao XIONG ShiYun ZHAO JianWei 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第5期799-810,共12页
Monolayer borophene, a novel kind of two-dimensional(2D) crystal, has been receiving intensive attention owing to its atomic thickness and metallic characteristics. Rational tuning the anisotropic electronic transport... Monolayer borophene, a novel kind of two-dimensional(2D) crystal, has been receiving intensive attention owing to its atomic thickness and metallic characteristics. Rational tuning the anisotropic electronic transport properties is essential to the application of monolayer borophene in electronic and optoelectronic devices. Herein, we developed an oxidation strategy to tune the anisotropic transport properties of borophene by changing O-defect coverage, using density functional theory combined with the nonequilibrium Green’s function formalism. It was found that for monolayer borophene, the preferable current flowing direction between armchair and zigzag could be reversed by modulating the surface O-defect coverage between 0 and 100%. The tunable anisotropic transport properties of oxidized borophene could be attributed to the interplay among several factors, including the surface charge transfer between O-defects and borophene layer, the scattering effects related to the coverage and orientation of O-B-O interfaces, and the additional transport channels through O-defects. Our work unveils the great potential of oxidization strategy in tuning the anisotropic electronic transport properties of monolayer borophene and is of significance to its application in high-performance electronic and optoelectronic nanodevices. 展开更多
关键词 borophene MONOLAYER ANISOTROPIC TRANSPORT O-defect COVERAGE carrier scattering TRANSPORT channel
硫磺和放线菌强化植物修复土壤镉污染 预览
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作者 张子杨 郭瞻宇 +3 位作者 管伟豆 郭堤 李荣华 张增强 《中国环境科学》 EI CAS CSCD 北大核心 2019年第5期2106-2114,共9页
为了强化耐受重金属镉(Cd)的植物包心芥菜对土壤中Cd污染的富集及转运效率,以包心芥菜为研究对象,向土壤中添加0.3%的硫磺和接种不同数量的放线菌Act12(0.5,1.0,1.5,2.0g/kg),通过盆栽实验,研究不同处理间根际土pH值的变化规律、包心芥... 为了强化耐受重金属镉(Cd)的植物包心芥菜对土壤中Cd污染的富集及转运效率,以包心芥菜为研究对象,向土壤中添加0.3%的硫磺和接种不同数量的放线菌Act12(0.5,1.0,1.5,2.0g/kg),通过盆栽实验,研究不同处理间根际土pH值的变化规律、包心芥菜地上和地下部分Cd的积累量、植物抗氧化酶系的变化以及根系活力.结果表明:添加0.3%硫磺和2.0g/kg放线菌Act12后,根际土pH值下降最大,相比对照下降了14.5%.而添加0.3%硫磺和1.5g/kg的放线菌Act12,包心芥菜地上部分Cd的含量最高,转运系数最大,相比对照,Cd含量提高了79%,并且植物地上部分的干重最大.添加放线菌Act12对植物的抗氧化系统有积极作用,CAT、POD、SOD含量均在0.3%硫磺和1.0g/kg放线菌Act12的添加组合下达到峰值,放线菌Act12还可提高植物的根系活力,降低丙二醛的含量.综上表明,添加硫磺和放线菌Act12均可强化包心芥菜吸收土壤中Cd的能力,其中0.3%硫磺和1.5g/kg放线菌Act12的添加组合强化效果最佳. 展开更多
关键词 放线菌Act12 硫磺 包心芥菜 抗氧化酶 转运 富集
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A field-effect approach to directly profiling the localized states in monolayer MoS2
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作者 Hao Wu Yuan Liu +10 位作者 Zeyu Deng Hung-Chieh Cheng Dehui Li Jian Guo Qiyuan He Sen Yang Mengning Ding Yun-Chiao Huang Chen Wang Yu Huang Xiangfeng Duan 《科学通报:英文版》 SCIE EI CSCD 2019年第15期1049-1055,共7页
A fundamental understanding of the charge transport mechanism in two-dimensional semiconductors(e.g., MoS2) is crucial for fully exploring their potential in electronic and optoelectronic devices. By using monolayer g... A fundamental understanding of the charge transport mechanism in two-dimensional semiconductors(e.g., MoS2) is crucial for fully exploring their potential in electronic and optoelectronic devices. By using monolayer graphene as the barrier-free contact to MoS2, we show that the field-modulated conductivity can be used to probe the electronic structure of the localized states. A series of regularly distributed plateaus were observed in the gate-dependent transfer curves. Calculations based on the variable-range hopping theory indicate that such plateaus can be attributed to the discrete localized states near mobility edge. This method provides an effective approach to directly profiling the localized states in conduction channel with an ultrahigh resolution up to 1 meV. 展开更多
关键词 Two-dimensional LAYERED materials FIELD-EFFECT transistor LOCALIZED STATES Electronic transport Conductivity plateau
Mass transport mechanisms within pervaporation membranes
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作者 Yimeng Song Fusheng Pan +2 位作者 Ying Li Kaidong Quan Zhongyi Jiang 《化学科学与工程前沿:英文版》 EI CAS CSCD 2019年第3期458-474,共17页
Pervaporation is an energy-efficient membrane technology for separating liquid molecules of similar physical properties, which may compete or combine with distillation separation technology in a number of applications... Pervaporation is an energy-efficient membrane technology for separating liquid molecules of similar physical properties, which may compete or combine with distillation separation technology in a number of applications. With the rapid development of new membrane materials, the pervaporation performance was significantly improved. Fundamental understanding of the mass transport mechanisms is crucial for the rational design of membrane materials and efficient intensification of pervaporation process. Based on the interactions between permeate molecules and membranes, this review focuses on two categories of mass transport mechanisms within pervaporation membranes: physical mechanism (solutiondiffusion mechanism, molecular sieving mechanism) and chemical mechanism (facilitated transport mechanism). Furthermore, the optimal integration and evolution of different mass transport mechanisms are briefly introduced. Material selection and relevant applications are highlighted under the guidance of mass transport mechanisms. Finally, the current challenges and future perspectives are tentatively identified. 展开更多
关键词 PERVAPORATION MEMBRANE mass transport MECHANISMS PHYSICAL MECHANISM chemical MECHANISM
Study on surface wave-induced mixing of transport flux residue under typhoon conditions 预览
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作者 YANG Yongzeng SHI Yongfang +2 位作者 YU Chencheng TENG Yong SUN Meng 《海洋湖沼学报(英文)》 CSCD 2019年第6期1837-1845,共9页
The transport flux residue of surface waves plays an important role in a variety of ocean phenomena,for example,the change in sea surface temperature(SST)and upper mixed layer profile that were studied in a series of ... The transport flux residue of surface waves plays an important role in a variety of ocean phenomena,for example,the change in sea surface temperature(SST)and upper mixed layer profile that were studied in a series of recent papers.In the previous studies,its effect was discussed rigorously and fragmented based on numerical modeling.Here we propose a relatively comprehensive and simplified exposition of the wave transport flux residue,and focus on its influence under typhoon conditions with strong background current.An analogue Reynolds Number is presented for tentative comparison with wave-generated turbulence mixing,especially in the coastal area.Numerical results indicate that both overwhelming dynamical mixing processes can remarkably change the coastal environment,and should not be ignored consciously for further marine hazards assessment. 展开更多
关键词 wave transport FLUX RESIDUE decomposition scheme ANALOGUE REYNOLDS Number
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新型防跑车防护装置的应用 预览
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作者 贾青霄 刘磊 吴传伟 《煤矿现代化》 2019年第3期103-105,共3页
采区轨道上山大绞车自动控制挡车栏,是用在倾斜井巷提升系统中防止跑车的专用设备,它与带有深度指示器的斜巷提升绞车配套使用,可实现巷道全程挡车栏自动控制。该挡车栏具有系统简单、安全可靠等优点,能够有效防止斜巷跑车事故的发生。... 采区轨道上山大绞车自动控制挡车栏,是用在倾斜井巷提升系统中防止跑车的专用设备,它与带有深度指示器的斜巷提升绞车配套使用,可实现巷道全程挡车栏自动控制。该挡车栏具有系统简单、安全可靠等优点,能够有效防止斜巷跑车事故的发生。但当发生跑车事故时,挡车拦在常闭状态下将矿车挡住防止跑车事故扩大的同时,由于车辆与挡车栏硬性撞击,往往发生挡车栏损坏的现象。为减少对挡车栏的损伤,减少影响提升运输时间,工区管理人员及技术人员集思广益,对现有挡车栏进行改造,增加了全断面绳栏缓冲器。采取新型挡车栏后,当跑车事故发生时,能够在缓冲器0.3~10m范围内有效阻拦车辆,减轻了对挡车栏的损伤,避免了跑车事故扩大。 展开更多
关键词 挡车栏 运输 车辆 缓冲器
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基于微分平滑的四旋翼运输系统轨迹跟踪控制 预览 被引量:1
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作者 梁晓 胡欲立 《控制理论与应用》 EI CAS CSCD 北大核心 2019年第4期525-532,共8页
四旋翼系绳运输系统是一种具有8个自由度和4个控制输入的欠驱动、强耦合、多变量的非线性系统.为建立系统模型,将系统解耦为双质点系绳连接子系统和四旋翼姿态控制子系统,基于广义拉格朗日方程推导出系统的动力学模型.然后利用微分平滑... 四旋翼系绳运输系统是一种具有8个自由度和4个控制输入的欠驱动、强耦合、多变量的非线性系统.为建立系统模型,将系统解耦为双质点系绳连接子系统和四旋翼姿态控制子系统,基于广义拉格朗日方程推导出系统的动力学模型.然后利用微分平滑理论证明了系统是以载荷位置和四旋翼偏航角为平滑输出的微分平滑系统.进而在等式限制条件下对平滑输出轨迹进行规划,获得前馈开环控制律.为抑制系统扰动并使跟踪误差收敛于原点,利用微分平滑特性推导出动态内反馈控制器.仿真实验验证了所提方法的有效性. 展开更多
关键词 四旋翼 运输 控制 平滑 动态反馈
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Tidal Asymmetry Changes in a Shallow Mud Estuary by a Restoration Project 预览
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作者 LIANG Huidi KUANG Cuiping +3 位作者 GU Jie MA Yue CHEN Kuo LIU Xu 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第2期339-348,共10页
The tidal asymmetry-induced siltation below tidal barriers is a worldwide problem that restricts regional socio-economic and environmental development.The hydrodynamic processes of the small mud estuary also feature a... The tidal asymmetry-induced siltation below tidal barriers is a worldwide problem that restricts regional socio-economic and environmental development.The hydrodynamic processes of the small mud estuary also feature a high uncertainty after estuary restoration measures.In this study,a hydrodynamic model based on the MIKE21 is used to quantify the responses of tidal asymmetry to a two-phase restoration project in Shuanglong Estuary,Bohai Bay,China.According to the numerical modeling results,the tidal flat removal in the upper estuary(first-phase restoration)induces the flood asymmetry switching to the ebb asymmetry in unrestored reach but enhances flood asymmetry in widening restored reach.Although the tidal asymmetry reverts to flood-dominated pattern after full restoration over the estuary,the imbalance between flood and ebb velocities is relieved.A possible net sediment transport pattern based on a comparison of dominant asymmetric current and actual sediment transport period shows net sediments in the upper estuary and inlet transport seaward and landward,respectively,in the first-phase restoration,whereas landward net sediment transport occurs in the whole estuary under the second-phase restoration scenario.Given these results,we assume that a switch from the flood-dominated estuary to ebb-dominated estuary can be caused by redesigning the cross-sectional profile.The quantitative comparison of Lagrangian residual currents also implies that a channel–shoal structure rather than a flat bathymetry can promote the mass transport.Therefore,reshaping the channel–tidal flat system in restoration projects can prevent the sedimentation of the estuary and improve the water environment. 展开更多
关键词 TIDAL asymmetry RESTORATION project MUD ESTUARY net SEDIMENT transport
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Treatment of forearm diaphyseal defect by distraction compression bone transport and continued distraction for radial head reduction:A case study
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作者 Nikolay M.Kliushin Paul Stepanenko Waleed A.Mekki 《中华创伤杂志:英文版》 CAS CSCD 2019年第5期304-307,共4页
Treatment of infected forearm nonunion and defects represents a difficult task for the operating sur-geons.Conventional methods like composite and vascularized fibular grafts and the induced membranes filled with canc... Treatment of infected forearm nonunion and defects represents a difficult task for the operating sur-geons.Conventional methods like composite and vascularized fibular grafts and the induced membranes filled with cancellous autografts or the Masquelet technique have been reported to be useful and suc-cessful,but sometimes it is difficult to predict the outcome and cannot address simultaneous deformities or the need to apply gradual distraction for reduction of a chronically dislocated radial head.Ilizarov technique has an answer for such conditions.We report a 43 years old man with infected ulnar defect and dislocated radial head as a result of infected Monteggia fracture:the patient was successfully treated by Ilizarov bone transport after failed attempts by bone spacer and fibular graft. 展开更多
关键词 Monteggia's fracture FOREARM defects ILIZAROV technique DISTRACTION HISTOGENESIS Bone transport
Nanoscale imaging of electric pathways in epitaxial graphene nanoribbons
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作者 Johannes Aprojanz Pantelis Bampoulis +2 位作者 Alexei A. Zakharov Harold J. W. Zandvliet Christoph Tegenkamp 《纳米研究:英文版》 CSCD 2019年第7期1697-1702,共6页
Graphene nanoribbons (GNRs) are considered as major building blocks in future carbon-based electronics.The electronic performance of graphene nanostructures is essentially influenced and determined by their edge termi... Graphene nanoribbons (GNRs) are considered as major building blocks in future carbon-based electronics.The electronic performance of graphene nanostructures is essentially influenced and determined by their edge termination and their supporting substrate.In particular,semi-conducting,as well as metallic GNRs,can be fabricated by choosing the proper template which is favorable for device architecture designs.This study highlights the impact of microscopic details of the environment of the GNRs on the charge transport in GNRs.By means of lateral force,conductive atomic force and nanoprobe measurements,we explore the charge propagation in both zig-zag and armchair GNRs epitaxially grown on SiC templates.We directly image transport channels on the nanoscale and identify SiC substrate steps and nano-instabilities of SiC facets as dominant charge scattering centers. 展开更多
关键词 SIDEWALL graphene NANORIBBONS NANOPROBE conductive-AFM NANOSCALE transport
Investigation on two triphenylene based electron transport materials
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作者 Minghan Cai Chongguang Zhao +2 位作者 Dongdong Zhang Xiaozeng Song Lian Duan 《中国科学:化学英文版》 SCIE EI CAS CSCD 2019年第6期775-783,共9页
Promoting electron mobility is the key to designing high performance electron transport materials(ETMs). Formation of intermolecular interaction can be helpful to enhance their electron mobilities as a result of more ... Promoting electron mobility is the key to designing high performance electron transport materials(ETMs). Formation of intermolecular interaction can be helpful to enhance their electron mobilities as a result of more ordered molecular stacking.Here, to reveal the inherent influence of intermolecular π-π stacking on the electron mobilities, we designed two ETMs, namely,2,4-diphenyl-6-[3-(2-triphenylenyl)phenyl]-1,3,5-triazine(TPTRZ) and 2,4-diphenyl-6-[4′-(2-triphenylenyl)[1,1′-biphenyl]-3-yl]-1,3,5-triazine(TPPTRZ). Thermal, photophysical and electrochemical measurement results indicate they are good ETM candidates. Additionally, TPTRZ and TPPTRZ exhibit high electron mobilities of 3.60×10-5 and 3.58×10-5 cm2V-1 s-1, respectively, at an electric field of 7×105 V cm-1. By taking X-ray single crystal structure, theoretical calculation and time of flight(TOF) results into consideration, it is revealed that strong intermolecular π-π stacking induced by planar triphenylene and triphenyltriazine units renders TPTRZ and TPPTRZ small energetic and positional disorder parameters, and results in their high electron mobilities thereby. By further enhancing intermolecular π-π stacking, ETMs with even higher electron mobilities can thus be anticipated. 展开更多
关键词 organic LIGHT-EMITTING diode ELECTRON transport material ELECTRON mobility π-π STACKING INTERMOLECULAR interaction
Configuration of propagator method for calculation of electron velocity distribution function in gas under crossed electric and magnetic fields
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作者 Hirotake SUGAWARA 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第9期1-18,共18页
This paper presents a self-contained description on the configuration of propagator method(PM)to calculate the electron velocity distribution function(EVDF) of electron swarms in gases under DC electric and magnetic f... This paper presents a self-contained description on the configuration of propagator method(PM)to calculate the electron velocity distribution function(EVDF) of electron swarms in gases under DC electric and magnetic fields crossed at a right angle. Velocity space is divided into cells with respect to three polar coordinates v,θ and f. The number of electrons in each cell is stored in three-dimensional arrays. The changes of electron velocity due to acceleration by the electric and magnetic fields and scattering by gas molecules are treated as intercellular electron transfers on the basis of the Boltzmann equation and are represented using operators called the propagators or Green’s functions. The collision propagator, assuming isotropic scattering, is basically unchanged from conventional PMs performed under electric fields without magnetic fields. On the other hand, the acceleration propagator is customized for rotational acceleration under the action of the Lorentz force. The acceleration propagator specific to the present cell configuration is analytically derived. The mean electron energy and average electron velocity vector in a model gas and SF6 were derived from the EVDF as a demonstration of the PM under the Hall deflection and they were in a fine agreement with those obtained by Monte Carlo simulations. A strategy for fast relaxation is discussed, and extension of the PM for the EVDF under AC electric and DC/AC magnetic fields is outlined as well. 展开更多
关键词 PROPAGATOR method ELECTRON velocity distribution function ELECTRON transport COEFFICIENTS CROSSED electric and magnetic fields MAGNETIZED plasma BOLTZMANN equation
A Call for Peace and Order
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作者 《北京周报:英文版》 2019年第33期26-27,共2页
Hong Kong’s transport network was partially paralyzed on August 5,as protesters created fresh chaos. Metro commuters were seriously affected by these actions, as many lines suspended operations.The metro system in Ho... Hong Kong’s transport network was partially paralyzed on August 5,as protesters created fresh chaos. Metro commuters were seriously affected by these actions, as many lines suspended operations.The metro system in Hong Kong transports about 5.8 million passengers a day. 展开更多
关键词 TRANSPORT NETWORK Hong Kong METRO COMMUTERS
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