Fujian Key Laboratory of Plasma and Magnetic Resonance

Xiamen, China

Fujian Key Laboratory of Plasma and Magnetic Resonance

Xiamen, China

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Qu X.,Xiamen University | Qu X.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Guo D.,Xiamen University | Cao X.,Shanghai JiaoTong University | And 2 more authors.
Sensors | Year: 2011

Reducing the acquisition time for two-dimensional nuclear magnetic resonance (2D NMR) spectra is important. One way to achieve this goal is reducing the acquired data. In this paper, within the framework of compressed sensing, we proposed to undersample the data in the indirect dimension for a type of self-sparse 2D NMR spectra, that is, only a few meaningful spectral peaks occupy partial locations, while the rest of locations have very small or even no peaks. The spectrum is reconstructed by enforcing its sparsity in an identity matrix domain with ℓp (p = 0.5) norm optimization algorithm. Both theoretical analysis and simulation results show that the proposed method can reduce the reconstruction errors compared with the wavelet-based ℓ1 norm optimization. © 2011 by the authors; licensee MDPI, Basel, Switzerland.


Liu R.-B.,Xiamen University | Liu R.-B.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Niu Z.-G.,Aerodynamics Research Institute | Wang M.-M.,Xiamen University | And 4 more authors.
Gongcheng Lixue/Engineering Mechanics | Year: 2016

To investigate the control effect of Spark Discharge Plasma Jets (SPJs) on the aerodynamic moments of a wing, SPJ generators were used for active flow control experimental study on an NACA0021 straight wing model. The location of SPJ generators along the chord of the airfoil, the jet flow direction relative to the chord, and the driving voltage parameters were changed to research the control effect and mechanism of SPJ generators on the aerodynamic moments of a wing model. The aerodynamic moments were measured with a six-component balance at a wind speed of 20 m/s. Two SPJ generators, arranged near the leading edge, reduced the rolling moment coefficient by a maximum of 0.0024 for angles of attack -4°~10°, but increased the rolling moment coefficient by a maximum of 0.0021 for angles of attack 12°~16°. The yaw moment coefficient was reduced by a maximum of 0.00097. The results show that aerodynamic moments control of wings can be realized using SPJs. The control effect of SPJs on the aerodynamic moments is changeable by adjusting the driving voltage frequency and the jet flow direction relative to the chord. © 2016, Engineering Mechanics Press. All right reserved.


Liu R.,China Aerodynamics Research And Development Center | Liu R.,Xiamen University | Liu R.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Niu Z.,Aviation Industry Corporation of China | And 6 more authors.
Science China Technological Sciences | Year: 2015

Spark discharge plasma synthetic jets (SPJs) have been used for the active flow control study on an NACA 0021 straight-wing model in a wind tunnel. The model forces and moments were measured using a six-component sting balance at a 20 m/s wind speed. The aim was to explore the SPJ’s effect on airfoil aerodynamic by examining SPJ generators’ position along the chordwise and the jet flow direction about the chord. Near the wing leading edge, two SPJ generators raised the stall angle by 2° and increased the maximum lift coefficient by 9%. The drag coefficient was decreased by 33.1%, and the lift-drag ratio was increased by 104.2% at an angle of attack above 16°. The rolling-moment coefficient was modified by 0.002, and the yawing-moment coefficient was changed by 0.0007 at angles of attack in the range of 0°–16°. The results showed that SPJs can control wing aerodynamic forces at a high angle of attack and moments at a low angle of attack. © 2015 Science China Press and Springer-Verlag Berlin Heidelberg


Liu R.B.,China Aerodynamics Research And Development Center | Liu R.B.,Xiamen University | Liu R.B.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Niu Z.G.,Aviation Industry Corporation of | And 7 more authors.
Science China Technological Sciences | Year: 2015

Spark discharge plasma synthetic jets (SPJs) have been used for the active flow control study on an NACA 0021 straight-wing model in a wind tunnel. The model forces and moments were measured using a six-component sting balance at a 20 m/s wind speed. The aim was to explore the SPJ’s effect on airfoil aerodynamic by examining SPJ generators’ position along the chordwise and the jet flow direction about the chord. Near the wing leading edge, two SPJ generators raised the stall angle by 2° and increased the maximum lift coefficient by 9%. The drag coefficient was decreased by 33.1%, and the lift-drag ratio was increased by 104.2% at an angle of attack above 16°. The rolling-moment coefficient was modified by 0.002, and the yawing-moment coefficient was changed by 0.0007 at angles of attack in the range of 0°–16°. The results showed that SPJs can control wing aerodynamic forces at a high angle of attack and moments at a low angle of attack. © 2015, Science China Press and Springer-Verlag Berlin Heidelberg.


Liu R.-B.,Xiamen University | Liu R.-B.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Sun W.,Xiamen University | Sun W.,Fujian Key Laboratory of Plasma and Magnetic Resonance | And 7 more authors.
Tuijin Jishu/Journal of Propulsion Technology | Year: 2015

A spark discharge plasma jet generator has been designed to obtain higher energy zero net mass flux jet, which can generate continuous jet flow at higher average speed and operate at normal atmospheric pressure with frequency up to 9 kHz. The structure of the generator was described and the discharge phenomenon of the plamsa jet was researched to find the mechanism in which how the plamsa jet generates the continuous jet flow at higher average speed. The average speed of the plamsa jet flow was measured by a pitot tube, to investigate how the electrical parameters and the gap between the two electrodes affect the average speed of the jet flow from the generator. The axial jet velocity distribution and the jet flow characteristics charts of the spark discharge plasma jet have been obtained as well. The experimental results show that the jet flow speed of the spark discharge plasma jet generator may reach more than 40 m/s continuously, which raises with the increasing of the loading voltage, and there exists the best gap between the two electrodes as well as the loading voltage frequency for a given jet generator. ©, 2015, Editorial Department of Journal of Propulsion Technology. All right reserved.


Liu R.,Xiamen University | Liu R.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Liu R.,Aeronautical Science and Technology Key Laboratory for Flight Simulation | Wang M.,Xiamen University | And 8 more authors.
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016

An air supplementing type plasma synthetic jet (ASPSJ) generator has been developed in this paper. A one-way check valve, increasing the air refill supply at the recover stage, is connected to a typical spark discharge plasma synthetic jet (PSJ) generator. The ASPSJ improves jet flow continuity of typical PSJ and can get higher energy synthetic jet. The effect of different valves on the maximum average jet flow speed is researched with different electric parameters. The best electric parameters for the highest synthetic jet flow speed are obtained by orthogonal test. For the test ASPSJ generators, the best loading voltage frequency, amplitude, and duty cycle are 150 Hz, 50 kV and 15%. The results show that ASPSJ strengthens the maximum average jet flow speed by above 20%. The best actuation frequency is increased, and the actuation frequency bandwidth for maximum jet flow speed enlarges from one point to 100 Hz. Better airflow control effect can be expected by ASPSJ in wind tunnel tests. The research results provide guidance for further active flow control application. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.


Zhang J.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Yu X.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Yu X.,Hunan University of Science and Technology | Yi P.,Fujian Key Laboratory of Plasma and Magnetic Resonance | And 5 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2010

To understand the 4-substituting group effects of organic ligands in pyridine ring on the reaction equilibrium, the interactions between a series of 4-picoline-like ligands and [OV(O2)2(D2O)]-/[OV (O2)2(HOD)]- in solution were explored by the combined use of multinuclear (1H, 13C, and 51V) magnetic resonance, DOSY, and variable-temperature NMR in 0.15 mol/L NaCl ionic medium for mimicking the physiological condition. Some direct NMR data are given for the first time. The reactivity among the 4-picoline-like ligands is 4-picoline > isonicotinate > isonicotinamide > ethyl isonicotinate. The competitive coordination results in the formation of a series of new six-coordinated peroxovanadate species [OV(O2)2L]n- (L = 4-picoline-like ligands, n = 1 or 2). The results of density functional calculations provide a reasonable explanation on the relative reactivity of the 4-picoline-like ligands. Solvation effects play an important role in these reactions. © 2009 Elsevier B.V. All rights reserved.


Huang Y.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Cai S.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Chen X.,Fujian Key Laboratory of Plasma and Magnetic Resonance | Chen Z.,Fujian Key Laboratory of Plasma and Magnetic Resonance
Journal of Magnetic Resonance | Year: 2010

A new pulse sequence based on intermolecular single-quantum coherences (iSQCs) is proposed to obtain high-resolution NMR spectroscopy in inhomogeneous magnetic fields via fast 2D acquisition. Taking the intrinsic properties of iSQCs, the sequence is time-efficient with a narrow spectral width in the indirect dimension. It can recover useful information of chemical shifts, relative peak areas, J coupling constants, and multiplet patterns even when the field inhomogeneity is severe enough to erase almost all spectroscopic information. Moreover, good solvent suppression efficiency can be achieved by this sequence even with imperfect radio-frequency pulse flip angles. Spatially localized iSQC spectroscopy was performed on a sample packed with pig brain tissue and cucumber to show the feasibility of the sequence in in vivo magnetic resonance spectroscopy (MRS). This sequence may provide a promising way for the applications on in vivo and in situ high-resolution NMR spectroscopy. © 2009 Elsevier Inc. All rights reserved.

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