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Li T.-T.,Shanghai University | Jia T.-G.,Central Academy | Jia T.-G.,East China University of Science and Technology | Fei M.-R.,Shanghai University | Hu H.-S.,University of Essex
International Journal of Automation and Computing | Year: 2011

The IEEE 802.15.4a standard provides a framework for low-data-rate communication systems, typically sensor networks. In this paper, we established a realistic environment for the time delay characteristic of industrial network based on IEEE 802.15.4a. Several sets of practical experiments are conducted to study its various features, including the effects of 1) numeral wireless nodes, 2) numeral data packets, 3) data transmissions with different upper-layer protocols, 4) physical distance between nodes, and 5) adding and reducing the number of the wireless nodes. The results show that IEEE 802. 15. 4a is suitable for some industrial applications that have more relaxed throughput requirements and time-delay. Some issues that could degrade the network performance are also discussed. © 2011 Institute of Automation, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg. Source

Liu S.,Sinopec | Liu S.,Central Academy | Xu Y.,Sinopec
Acta Petrologica Sinica | Year: 2013

The effects of operation parameters, such as catalyst microactivity and the mass ration of catalyst to oil ratio(CTO) on aromatics conversion and coking in VGO catalytic cracking process were investigated with a laboratory fixed fluidized bed reactor. According to the coke yield change and the reaction conversion rate, the VGO catalytic cracking process was divided into three stages, in which the relationship between aromatics conversion and coking was investigated, respectively. The concept of apparent catalyst activity (ACA) was defined. The relationships between the apparent catalyst activity and the gasoline aromatics molar yield as well as the coke mass yield were studied. By analyzing the aromatic content and coke amount changing in all distillates, it was found that aromatics, especially polycyclic aromatics were essential on coke formation. Under the condition of the same mass ratio of catalyst to oil, the gasoline aromatic content and coke yield increased with the increase of catalyst microactivity. Under the condition of the same conversion rate, the coke yield increased with the increase of apparent catalyst activity. Source

Hu Y.,East China University of Science and Technology | Niu Y.,East China University of Science and Technology | Chen B.,Central Academy
Chinese Control Conference, CCC | Year: 2015

Clustering is an energy efficient routing protocol for wireless sensor networks. Traditional clustering methods can prolong the network lifetime and achieve scalable performance, but they do not consider the event development. In many applications, the scalability and occurrence region of events often change. A dynamic clustering method with overlaps (DCMO) is proposed in this paper. Due to the 2-logical-coverage overlaps of the proposed clustering method, the clusters can be migrated with the changing tendency of events. As a result, the sensed data can be transmitted at a lower price. Simulations show that the proposed DCMO method has lower energy consumption, compared with LEACH protocol. © 2015 Technical Committee on Control Theory, Chinese Association of Automation. Source

Zhan C.,Shanghai JiaoTong University | Pan Y.,Central Academy | Wang Z.,Shanghai JiaoTong University | Wang Y.,Shanghai JiaoTong University | And 2 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

Experimental evidences show that the gas ionization induced positive charge accumulation can lead to the field electron emission from carbon nanotubes, partially covered with ethocel thin film and ZnO nanorods. This effect can lead to a novel ionization gas sensing mechanism, which can be used to identify the gaseous chemical composition based on the characteristic resistivity of the gases without strong field effect of field ionization and gaseous breakdown. The hypothesis for illustration is suggested that: (1) the cosmic ray ionization frequency increases 108-1010 times due to the metastable population resulted from the interaction between the gases and the CNTs; (2) the flux of positive charges is converged due to the ZnO nanorods. The resulted positive charge local density is high enough to trigger the field emission. The experimental results are shown to be in consistent with the theoretical expectations, qualitatively. The methodology is advantageous in the context of the ionization gas sensors because its I-V characteristics are linear so that the signals can be sampled more easily than that of the gaseous breakdown critical voltage sampling. Besides, the device does not suffer from the degradation effect in the gaseous breakdown processes and exhibits better repeatability. © 2013 Elsevier B.V. All rights reserved. Source

Li Y.,Tsinghua University | Qu T.,Tsinghua University | Gu C.,Tsinghua University | Jiang Y.,Central Academy | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2015

Concept design and optimization for a high-temperature superconducting (HTS) rotor of a 100-kW generator is studied in this paper. The rotor has eight HTS magnets constructed by air-cored racetrack coils. The HTS magnets with a unique circular cross-sectional shape can produce a gap field over 2.0 T. The present design is based on a new graphical method developed to estimate the maximum operating current of an HTS magnet that takes both Ic-B characteristics and angular dependence into consideration. The optimized stepped shape design saved more than 8% of the HTS material compared with the rectangular one without sacrificing the gap field. © 2002-2011 IEEE. Source

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