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Yang Z.,Tsinghua University | Yang Z.,National Laboratory for Information Science and Technology | Tao H.,Tsinghua University | Tao H.,National Laboratory for Information Science and Technology | And 3 more authors.
Proceedings of the 2012 National Conference on Information Technology and Computer Science, CITCS 2012 | Year: 2012

Based on the three-layer model theory for steganography communication system, this paper designs a new steganography transmission protocol, to achieve a more effective frame structure, more reliable transmitting mechanism. Both text message dialogue and file transmission communication based on the proposed method are reliable while the performance is also corresponding improvement. The experimental results has proved theoretical prediction that the proposed protocol is able to achieve reliable and efficient steganography on VoIP network. © 2012. The authors - Published by Atlantis Press.

Xu L.,Tsinghua University | Li J.,Tsinghua University | Ouyang M.,Tsinghua University | Hua J.,Tsinghua University | Yang G.,National Laboratory for Information Science and Technology
International Journal of Hydrogen Energy | Year: 2014

A proton electrolyte membrane (PEM) fuel cell system and a Li-ion battery (LIB) are two power sources in a fuel cell electric vehicle (FCEV). The fuel cell system is composed of a fuel cell stack and subsystems for air/hydrogen supply and cooling water. The operation procedure of the fuel cell system can be generally separated into several processes, e.g. starting up, normal/abnormal working and shutting down. In this paper, a multi-mode real-time control strategy for a FCEV is proposed. The strategy is established based on three typical processes (starting up, normal working, shutting down) of the fuel cell system, taking the fuel economy and system durability into consideration. The strategy is applied into a platform vehicle for the 12th 5-year project of "the next generation technologies of fuel cell city buses". Experiments of the "China city bus typical cycle" on a test bench for the bus were carried out. Results show that, the fuel economy is 7.6 kg (100 km)-1 in the battery charge-sustaining status. In a practical situation, a total driving mileage of more than 270 km can be achieved. Cycle testing also showed that, the degradation rate of the fuel cell was reduced to half of the original level. No performance degradation of the LIB system was observed in the cycling test. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.

Wang Z.,Tsinghua University | Wang Z.,North China Electrical Power University | Wang Z.,National Laboratory for Information Science and Technology | Wang Z.,PLA Logistical Engineering University | And 10 more authors.
Information Systems | Year: 2014

Product lifecycle management (PLM) systems are widely used in the manufacturing industry. A core feature of such systems is to provide support for versioning of product data. As workflow functionality is increasingly used in PLM systems, the possibility emerges that the versioning transitions for product objects as encapsulated in process models do not comply with the valid version control policies mandated in the objects' actual lifecycles. In this paper we propose a solution to tackle the (non-)compliance issues between processes and object version control policies. We formally define the notion of compliance between these two artifacts in product lifecycle management and then develop a compliance checking method which employs a well-established workflow analysis technique. This forms the basis of a tool which offers automated support to the proposed approach. By applying the approach to a collection of real-life specifications in a main PLM system, we demonstrate the practical applicability of our solution to the field. © 2014 Elsevier Ltd.

Xiao L.,National Laboratory for Information Science and Technology | Xiao L.,North China Electrical Power University | Xiao L.,Tsinghua University | Wang R.,National Laboratory for Information Science and Technology | And 8 more authors.
Mathematical and Computer Modelling | Year: 2012

PLC is widely used in the field of automatic control. To use formal methods to verify the correctness of PLC programs, semantic characterization of PLC programs are needed. Based on the extended λ-calculus definition, this paper presents a novel semantic modeling of PLC programs. The results lay the solid underpinnings for theorem proving and modeling checking for PLC systems. © 2011 Elsevier Ltd.

Wu H.,Tsinghua University | Zhao X.,Tsinghua University | Li Y.-S.,Tsinghua University | Long G.-L.,Tsinghua University | Long G.-L.,National Laboratory for Information Science and Technology
International Journal of Quantum Information | Year: 2010

We propose a new way of description of the global entanglement property of a multi-partite pure state quantum system. Based on the idea of bipartite concurrence, by dividing the multi-partite quantum system into two subsystems, a combination of all the bipartite concurrences of a multi-partite quantum system is used to describe the entanglement property of the multi-partite system. We derive the analytical results for GHZ-state, W-state with arbitrary number of qubits, and cluster state with the number of particles no greater than 6. © 2010 World Scientific Publishing Company.

Wei Y.,Tsinghua University | Xiong Z.,Tsinghua University | Jiang Y.,Tsinghua University | Huang D.,Tsinghua University | Huang D.,National Laboratory for Information Science and Technology
Chinese Control Conference, CCC | Year: 2014

It is necessary for polyethylene grade transitions to establish dynamic optimization in order to preserve competitiveness in the global polymer market. Although the typical technology of iterative learning control has been performed to track the reference trajectories, it is usually difficult to obtain the optimal reference trajectories. A transition from one specific grade to another specific grade can be considered as one batch, therefore, we propose a feasible scheme for dynamic optimization of polyethylene grade transitions based on the batch reinforcement learning, which can derive a best possible policy after a few batches. The scheme aims to integrate the offline reference optimization and online implementations, and explore a better control policy instead of tracking the predetermined trajectories. This designed scheme has three distinct phases, collecting observations from reference and the historical trajectories, learning a policy, and executions. The proposed method is verified by the simulated polyethylene grade transitions, and good performance has been obtained. © 2014 TCCT, CAA.

Pei D.,Intelligent Systems Technology, Inc. | Pei D.,National Laboratory for Information Science and Technology | Sun F.,Intelligent Systems Technology, Inc. | Sun F.,National Laboratory for Information Science and Technology | And 2 more authors.
IEEE Signal Processing Letters | Year: 2013

Correlations in image sequences can be potentially useful for recovering feature representation and subsequently prompting classification performance, which are often neglected by traditional classification approaches. In this letter, we present a supervised low-rank matrix recovery model to leverage these correlations for classification tasks by introducing a supervised penalty term to the classic low-rank matrix recovery model. This allows us to not only exploit these correlations to recover the underlying feature representation from corrupted observation, but also preserve discriminative information for classification. Our model is evaluated on both real-world data and synthetic data, and experimental results show that our model obtains highly competitive performance with state-of-the-art algorithms and is especially robust to different levels of corruptions. © 1994-2012 IEEE.

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