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Lei S.,Catholic University of Leuven | Lei S.,Academy of Fundamental and Interdisciplinary science | Tahara K.,Osaka University | Adisoejoso J.,Catholic University of Leuven | And 3 more authors.
CrystEngComm | Year: 2010

Surface-confined porous molecular networks can be formed by self-assembly at the liquid-solid interface by controlling the subtle interplay between molecules, solvent and substrate. Typically, directional interactions such as hydrogen bonding or metal-ligand interactions are at play in defining the topology of the networks. However, porous molecular networks maintained only by van der Waals interactions are at the focus in this Highlight. The liquid-solid interface at atomically flat conductive substrates such as graphite is an excellent medium to support the self-assembly of alkylated molecules. Molecular symmetry defines the shape of the pores, ranging from diamond to honeycomb and Kagomé. Solvent often plays an important role and sometimes several porous and non-porous structures are formed. The solute concentration is a key factor too, the formation of porous patterns is favoured at low concentrations. These pores, with diameters ranging from about three nanometres to more than seven nanometres, can be filled with guest molecules. In some cases, these porous topologies can only be formed upon addition of template molecules, which direct the structural transformation from a high-density to a low-density, i.e. porous, phase. The template molecules stabilize the pores. Following appropriate design principles, multicomponent networks can be formed, containing up to four different organic molecules. © 2010 The Royal Society of Chemistry. Source

Hao X.,Harbin Institute of Technology | Chang J.,Harbin Institute of Technology | Chang J.,Academy of Fundamental and Interdisciplinary science | Bao W.,Harbin Institute of Technology | And 2 more authors.
Aerospace Science and Technology | Year: 2016

Intricate process of mode transition exists in dual-mode scramjet engines, mainly amongst three typical operation modes (i.e., scramjet mode, ramjet mode and unstarted mode). Based on the analysis of an original analytical model, four transition boundaries are defined, and several corrections and considerations are carried out to clarify the way how to develop a model of mode transition logic. The complete mode transition logic is presented in a flowchart with a calculated case, and the corresponding implementation method for simulation is specified with programs in the paper. Combining the present mode transition logic unit with the original analytical parts, a dual-mode scramjet engine model for simulation, in which the inlet unstart issue is mainly caused by the interaction between thermodynamic effect and geometrical effect, could be acquired. © 2015 Elsevier Masson SAS. Source

Li Y.,CAS National Center for Nanoscience and Technology | Wan J.,Hangzhou Normal University | Deng K.,CAS National Center for Nanoscience and Technology | Han X.,CAS Beijing National Laboratory for Molecular | And 5 more authors.
Journal of Physical Chemistry C | Year: 2011

We have designed and synthesized one molecular building block, an aromatic trialdehyde derivative with three aldehyde groups, to form a potentially active structure. The scanning tunneling microscopy (STM) images show that the trialdehyde derivative forms lamellar structures. By the addition of active reactant, 5-aminoisophthalic acid, it is found that the structure of the adlayer can be transformed from lamellar to hexagonal structure as was expected. The structural formation of molecular networks is attributed to the condensation reaction between aldehyde and amine. Density functional theory (DFT) calculations reveal the observation of structural transformation at the solid/liquid interface due to the more stable adsorption of the triimine product than that of the trialdehyde derivative. © 2011 American Chemical Society. Source

Chang J.,Harbin Institute of Technology | Chang J.,Academy of Fundamental and Interdisciplinary science | Wang L.,Harbin Institute of Technology | Bao W.,Harbin Institute of Technology
49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference | Year: 2013

Hysteresis phenomenon in ramjet/scramjet was studied seldom although it has frequently been observed in aerodynamic experiments. The current works aim to investigate experimentally the hysteresis phenomenon in a scramjet engine that is caused by excessive heat release from combustion. The experiments were conducted in a direct-connect scramjet engine in Mach 3.0 flow. To determine the hysteresis characteristics, many runs under different changes in fuel equivalence ratio were carried out. The experimental results show that there exists an obvious hysteresis phenomenon in mode transition between inlet start and unstart, and the changes in fuel equivalence ratio have a little effect on hysteresis phenomenon. Thus, a prior knowledge of hysteresis effects will benefit the restart control. Moreover, the hysteresis effect has a great effect on unstart control, which demands a far reduction in fuel for inlet restarting. Source

Wei X.Q.,Harbin Institute of Technology | Zhang X.J.,Academy of Fundamental and Interdisciplinary science | Yu H.,Harbin Institute of Technology | Song S.M.,Harbin Institute of Technology
Proceedings of the 2nd International Conference on Intelligent Control and Information Processing, ICICIP 2011 | Year: 2011

The particle filter is a Monte Carlo method that allows us to treat any probability distribution, nonlinear and non-Gaussian. However the choice of the proposal distribution is the most critical problem. Unscented particle filter (UPF) uses UKF to generate and propagate the Gaussian distribution which provides a better approximation to the optimal conditional proposal distribution. It is not practical to fulfill the requirement for large-scale problems that the number of the sigma points will be larger than twice the degree-of-freedom of the system model. To overcome this difficulty, a new particle filter equipped with ensemble unscented Kalman filter (EnUKF) is proposed with the name EnUPF. The analyses indicate that EnUPF needs less computational cost and simulation validate the similar performance to UPF. © 2011 IEEE. Source

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