Beijing Jiaotong University Research Articles

Arc-transitive Pentavalent Graphs of Order 4pq

This paper determines all arc-transitive pentavalent graphs of order $4pq$, where $p,q\ge 5$ are distinct primes. The cases $q=1,2,3$ and $q=p$ is a prime have been treated previously by Hua et al. [Pentavalent symmetric graphs of order $2pq$, Discrete Math. 311 (2011), 2259-2267], Hua and Feng [Pentavalent symmetric graphs of order $8p$, J. Beijing Jiaotong University 35 (2011), 132-135], Guo et al. [Pentavalent symmetric graphs of order $12p$, Electronic J. Combin. 18 (2011), #P233] and Huang et al. [Pentavalent symmetric graphs of order four time a prime power, submitted for publication], respectively.

Introduction: advances in E-business engineering

E-business is one of the most exciting and challenging research areas [9, 10, 14]. Today, not only large companies, but also medium or small-sized companies are learning that e-business is a required component of doing business. E-business has rapidly evolved in the last decade and this trend will continue. In this rapid process, a variety of e-business engineering methods and techniques have been developed [28]. There are many research issues needed to be addressed. As a result, there is a growing demand for insights into challenges, issues, and solutions related to the design, implementation, and management of e-business systems. To respond to the needs from both academic researchers and practitioners for communicating research results on e-business engineering and related topics, a number of related conferences organized by the IFIP TC8 WG8.9, IEEE SMC Society Technical Committee on Enterprise Information Systems, and other major research institutions have been held in the past years. Such conferences include IFIP International Conference on Research and Practical Issues of Enterprise Information Systems (Confenis), IEEE SMC International Conference Special Session on Enterprise Information Systems, International Forum of Information Systems Frontiers (IFISF), International Conference on Natural Language Processing and Knowledge Engineering, GCIS, and WCSE [19]. These conferences plus workshops organized by IFIP and IEEE have provided an international forum for researchers in academia and industry to present their most recent findings in e-business engineering. This special issue of Information Technology and Management presents expanded versions of 20 papers from the above-mentioned conferences held recently, authored by scholars from Austria, China, Japan, Russia, UK, and US. The purpose of this special issue is to report on the state-of-the-art of, and emerging trends in, research and practice in e-business engineering. To prepare for this issue, all authors were asked to respond to at least two rounds of peer review. Each paper emphasizes the importance of e-business engineering from a unique perspective. IoT is an emerging Internet-based industrial information architecture that can be employed to facilitate information flow in global supply chain networks [36]. An effective strategy of IoT can help firms to grasp the emerging opportunities from the IoT and improve competitive advantages. In the paper entitled ‘‘Towards a theoretical framework of strategic decision, supporting capability and information sharing under the context of Internet of Things’’, Li et al. of Shanghai Jiaotong University provide a theoretical framework which classifies IoT strategies into four archetypes from two dimensions of managers’ strategic intent and industrial driving force, and propose that market-based S. Xu Beijing Jiaotong University, Beijing 100044, China

Luminescence Characteristics of Blue Emission Phosphorescent Material Firpic

The luminescent properties of bis[(4,6-difluorophenyl)-pyridinato-N,Cʹ]c(picolinate)iridium(III) (FIrpic) dependence on the doping concentrations and different annealing treatments were investigated. The color of emission from thin films and organic light emitting diodes (OELDs) could be adjusted from blue to yellow-green by controlling the FIrpic doping concentration. There was good spectral overlap from 440 to 480 nm between the FIrpic photoluminescence (PL) spectra and its absorption spectra. The 476 nm emission intensity decreased as the FIrpic doping concentration increased, and this effect could be attributed to FIrpic self-absorption. The PL and electroluminescence (EL) spectra were measured under different excitation power densities and in different doping concentrations, respectively. The intensity of emission peak at 530 nm was enhanced as the excitation power density or FIrpic doping concentration increased. This suggests that the emission peak at 530 nm originates from the excimer emission between FIrpic molecules. The morphologies of the thin film and changes in the EL spectra were analyzed before and after annealing treatment. This demonstrated that FIrpic molecular aggregation promoted by annealing [Article] www.whxb.pku.edu.cn 物理化学学报(Wuli Huaxue Xuebao) Acta Phys. -Chim. Sin. 2012, 28 (4), 949-956 April Received: November 23, 2011; Revised: January 5, 2012; Published on Web: January 16, 2012. ∗Corresponding author. Email: fjzhang@bjtu.edu.cn; Tel: +86-10-51684908. The project was supported by the National Key Basic Research Program of China (973) (2010CB327704), National Natural Science Foundation of China (10804006, 60576016), National Outstanding Young Scientists Foundation of China (60825407), Natural Science Foundation of Beijing, China (1102028), Program of Introducing Talents of Discipline to Universities, China (B08002), Fundamental Research Funds for the Central Universities, China (2011JBM123, 2010JBZ003), and Talent Plan of Red Berry of Beijing Jiaotong University, China. 国家重点基础研究发展规划(973) (2010CB327704),国家自然科学基金(10804006, 60576016),国家杰出青年基金(60825407),北京市自然科学 基金(1102028),高等学校学科创新引智计划(B08002),高等学校基本科研业务基金(2011JBM123, 2010JBZ003)及北京交通大学红果园人才计 划资助 C Editorial office of Acta Physico-Chimica Sinica doi: 10.3866/PKU.WHXB201201163 949 Acta Phys. ⁃Chim. Sin. 2012 Vol.28 treatment could increase the intensity of excimer emission between FIrpic molecules. The emission color of OLEDs could be adjusted from blue to yellow-green by changing the FIrpic doping concentration, optimizing the device structure, and using annealing treatment on the devices.

Study on Capacity Bottlenecks Identification and Elimination of XiErQi Station in Beijing MTR Based on Simulation Method

Due to the capacity limitation, congestions caused by the excessive amount of passenger flow appear in many Mass Transit Railway(MTR) hubs. Computer simulation is one of the most effective way to solve this problem. In this paper, an identification and elimination of capacity bottlenecks method was proposed based on dynamic movement of passengers simulation. Possible optimized solution was investigated through a case study in XiErqi Station, which is the transfer hub of Line13 and Changping Line in Beijing MTR. The proposed model was validated both statically and experimentally. Two optimization measures were dicussed after digging out the passenger feature and the essence of the congestions. One is improving passenger flow organization, the other is reforming operation organization. Then the simulate experiments were done through a proprietary software developed by Beijing Jiaotong University----SRail System. The simulation result shows congestion was alleviated effectively. It is proved that the method is feasible and effective.

Low frequency vibration tests on a floating slab track in an underground laboratory

Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the characteristics of low frequency vibrations and the low frequency performance of a floating slab track (FST), low frequency vibration tests on an FST in an underground laboratory at Beijing Jiaotong University were carried out. The FST and an unbalanced shaker SBZ30 for dynamic simulation were designed for use in low frequency vibration experiments. Vibration measurements were performed on the bogie of the unbalanced shaker, the rail, the slab, the tunnel invert, the tunnel wall, the tunnel apex, and on the ground surface at distances varying from 0 to 80 m from the track. Measurements were also made on several floors of an adjacent building. Detailed results of low frequency vibration tests were reported. The attenuation of low frequency vibrations with the distance from the track was presented, as well as the responses of different floors of the building. The experimental results could be regarded as a reference for developing methods to control low frequency vibrations and for adopting countermeasures.

Solar cells based on the poly(N-vinylcarbazole): porphyrin: tris(8-hydroxyquinolinato) aluminium blend system* *Project supported by the National Natural Science Foundation of China (Grant Nos. 60978060 and 50602008), the BeijingMunicipal Science & Technology Commission (Grant No. Z090803044009001), and the Excellent Doctor's Science and TechnologyInnovation Foundation of Beijing Jiaotong University of China (Grant No. 141107522).

Organic solar cells based on poly(N-vinylcarbazole) (PVK): porphyrin: tris (8-hydroxyquinolinato) aluminium (Alq3) blend p-n junction systems have been fabricated in this work. The roles of the different components in the blend system and of the amount of porphyrin have been investigated. The 5, 10, 15, 20-tetraphenylporphyrin (TPP) and 5, 10, 15, 20-tetra(o-chloro)phenylporphyrinato-copper (CuTClPP) are used in the solar cells. The results show that TPP is better than CuTCIPP in enhancing the performance of PVK:Alq3 solar cells. When the weight ratio of PVK:TPP:Alq3 is 1:1.5:1, the best performance of solar cell is obtained. The open circuit voltage (V oc) is 0.87 V, and the short circuit current (J sc) is 17.5 μA·cm−2. In the ternary bulk hereojunction system, the device may be regarded as a cascade of three devices of PVK:TPP, TPP:Alq3 and PVK:Alq3. PVK, TPP and Alq3 can improve the hole mobility, light absorption intensity and electron mobility of the ternary bulk hereojunction system, respectively.

Optimization of a GaN-based irregular multiple quantum well structure for a dichromatic white LED**Project supported by the National Natural Science Foundation of China (Grant No. 60777013), the Nature Science Foundationof Beijing, China (Grant No. 4082023), and the Excellent Doctoral Science and Technology Innovation Foundation of Beijing Jiaotong University, China (Grant No. 141063522).

GaN-based irregular multiple quantum well (IMQW) structures assembled two different types of QWs emitting complementary wavelengths for dichromatic white light-emitting diodes (LEDs) are optimized in order to obtain near white light emissions. The hole distributions and spontaneous emission spectra of the IMQW structures are analysed in detail by fully considering the effects of strain, well-coupling, valence band-mixing and polarization effect through employing a newly developed theoretical model from the k · p theory. Several structure parameters such as well material component, well width, layout of the wells and the thickness of barrier between different types of QWs are employed to analyse how these parameters together with the polarization effect influence the electronic and the optical properties of IMQW structure. Numerical results show that uniform hole distributions in different types of QWs are obtained when the number of the QWs emitting blue light is two, the number of the QWs emitting yellow light is one and the barrier between different types of QWs is 8nm in thickness. The near white light emission is realized using GaN-based IMQW structure with appropriate design parameters and injection level.

Interview

Professor Ai Bo from Beijing Jiaotong University in China is Vice Director of The State Key Laboratory of Rail Traffic Control and Safety. Here he talks about the research behind his group's Letter ‘Propagation measurements and analysis for high-speed railway cutting scenario' on page 1167.

The role of general practitioners as "gatekeeper" in university health service center

The article reviewed the function of general practitioners in Beijing Jiaotong University Health Service Center, which was transitioned from sole curative service to both curative and preventive services. The article also discussed the role as gatekeeper for health system played by practitioners in university health service centers. Key words: Community health services; General practitioner

Oxidation layer in sliding friction surface of high-purity Ti3SiC2

Oxidation layer in sliding friction surface of high-purity Ti₃SiC₂

Instabilities of sliding friction governed by asperity interference mechanisms

Due to the randomness in interferential resistances generated from asperities paired between friction surfaces, the sliding friction coefficient always turbulently fluctuating. This instability was modeled with a statistical approach based on observations and analyses for the interference mechanism of asperities in the present work. The model verified in theory that the turbulent fluctuation of friction coefficient in value yields to a normal distribution, and that both of the expectation and the standard deviation are functions of material properties, friction surface state, and normal pressure applied. Besides, the standard deviation is a negative 1/2-power function of the nominal area of friction surface. Three kinds of material pairs, including silicon carbon particulate reinforced aluminum alloy (SiC–Al) against carbon matrix composites (CMC), were tested on a block-on-disk type friction tester developed by Beijing Jiaotong University, with different normal pressures and sliding speeds, for examining the probability distribution of friction coefficient. The material pair of SiC–Al against CMC was also tested with several normal pressures from 0.1 to 0.8 MPa and the same sliding speeds of 30 m/s, for discussing effects of normal pressure on the expectation and the standard deviation of friction coefficient. The results showed that, all sets of test data of friction coefficient, for the saturation period of a friction process, have obvious characteristics of normal distribution, being in very good agreement with the theoretical model. In terms of the present data, the effects of normal pressure showed non-monotonic change tendencies for both of the expectation and the standard deviation. The expectation had a maximum value nearby the normal pressure of about 0.2 MPa; it rapidly increased to the maximum and then gradually reduced with normal pressure increase. The standard deviation showed the similar change tendency. In addition, the effect of the nominal area on the standard deviation was demonstrated to be essentially in agreement with the theoretical result.