G. Liang

Sam Houston State University, Huntsville, Texas, United States

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Publications (82)224.8 Total impact

  • L. Zhang · X. He · Z. Wei · G. Liang
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    ABSTRACT: As the highest measurement precision attitude sensor, attitude determination is the most basic and critical section in navigation. To analyze the impact of star distribution on least square attitude measuring precision, the definition of the attitude angle was described, the problem-solving process by least square method was researched, and the condition number of the coefficient matrix, that leads to poor precision under a certain observational error, was derived from the view of mathematical. Lastly, three sets of typical star distribution under different conditions were simulated, calculate the results and conduct the statistics, the simulation results indicate that measurement precision is influenced by different locations of the star group in image and different device parameter models for star sensor, besides the relative position of the star group described by condition number.
    No preview · Article · Jun 2014
  • Zhang L. · G Liang · G Peng · Y Huang · L Wang · L Qie · M Croft · A Ignatov · J Goodenough

    No preview · Article · Aug 2012 · Journal of The Electrochemical Society
  • G.liang · M.li · J. T.markert · L. V.wang
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    ABSTRACT: Single crystals Nd2-xCexCuO4-δ with x=0.0 and 0.2 are studied by polarized X-ray absorption measurements at Cu K-edge. The positions and intensities of the 1s→ 4pσ transition features in the K-edge spectra are analyzed with a modified cluster model and functional curve fitting procedure. All of the experimental results including the energies of the spectral features, the energy separations between features and the variation of feature intensities, can be well explained by the cluster model parameters obtained from the curve fitting. Particularly, it is found that the charge transfer energy gap Δ in the Nd2-xCexCuO4-δ system decreases from about 1.4 eV at x=0 to 0.5 eV at x = 0.2. Our analysis in this paper provides a method for quantitative X-ray absorption spectroscopy (XAS) study of the charge transfer gap for electron-doped cuprate superconductors and related materials.
    No preview · Article · Jan 2012 · International Journal of Modern Physics B
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    G.liang · Y.yi · R. F.jardim · L. V.wang
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    ABSTRACT: To further study the charge carrier concentration in electron doped cuprate superconductors. a systematic x-ray absorption near edge structure (XANES) measurement has been carried out on Th-doped superconductor system R2-xThxCuO4-δ (R=Nd, Sm, and Gd). The XANES results show that, similar to the Ce-doped compounds, while the intensity of the Cu1+4pπ feature increase with the increase of the Th doping level x, the intensities of the Cu2+4pπ and 4pσ features decreases. This clearly indicates that the electrons doped by the Th atoms are injected into the local Cu 3d-orbitals. The normalized Cu1+4pπ intensity data show that the Cu1+ concentration in the Th-doped compound series with different R-elements is linearly proportional to the Th doping-level x. The data suggest that both Ce and Th donate the same fraction of electrons into the Cu sites.
    Full-text · Article · Jan 2012 · International Journal of Modern Physics B
  • G.liang · R. S.liu · L. V.wang
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    ABSTRACT: Near-edge x-ray-absorption spectra at the Cu K-edge has been measured for (Tl0.5Pb0.5)Sr2Ca1-xYxCu2O7-δ compound series. It is found that both the intensity of the quadruple 1s → 3d transition feature and the edge-energy decrease with increasing x. Our results show that the Cu valence decreases slightly with the substitution of Ca+2 by Y+3. This result, together with recent O K-edge result the O-2p holes are reduced by the substitution, indicates that electronic charge is transferred into the entire CuO2 layers by the Y+3 for Ca+2 substitution.
    No preview · Article · Jan 2012 · International Journal of Modern Physics B
  • G.liang · R. S.liu · L. V.wang
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    ABSTRACT: Near edge x-ray-absorption spectra at Pb L3-edges have been measured for (Tl0.5Pb0.5)Sr2Ca1-xYxCu2O7-δ compound series. It is found that the intensity of the 2p→6s transition feature decreases with the substitution of Ca+2 by Y+3. This result indicates that some electronic charges have been transferred into the Pb(Tl)-O layers by this substitution. Detailed analysis suggests that the valence value of Pb in this compound series is close to +4 and it decreases with the increase of the Y-doping level x.
    No preview · Article · Jan 2012 · International Journal of Modern Physics B
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    G. Liang · H. Fang · Z.P. Luo · S. Keith · C. Hoyt
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    ABSTRACT: The effects of the grain size of the doped SiC nanoparticles on the critical current density ( J <sub>c</sub>) of the Ti-sheathed MgB<sub>2</sub> superconducting wires were studied. The concentration of the SiC dopant was 10% and the sizes of the SiC particles were 20 nm, 45 nm, and 123 nm. Contrary to the J <sub>c</sub> results reported on the SiC-doped Fe-sheathed MgB<sub>2</sub> wires, we found that the J <sub>c</sub> for the Ti-sheathed MgB<sub>2</sub> wires decreased with the size of the SiC particles. We also found that the J <sub>c</sub> is greater than that of the undoped MgB<sub>2</sub> wires only for the wires with 123 nm SiC size. This unusual dependence of J <sub>c</sub> on the size of the SiC dopant is discussed in association with the results from the magnetization, electrical resistivity, x-ray diffraction, and transmission electron microscopy measurements.
    Full-text · Article · Jul 2011 · IEEE Transactions on Applied Superconductivity
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    G. Liang · H. Fang · S. Guchhait · C. Hoyt · J. T. Markert
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    ABSTRACT: The effects of sintering temperature on the superconducting properties of Ti-sheathed MgB2 wires have been studied. The wires were fabricated by in situ powder-in-tube (PIT) method and characterized by x-ray diffraction, magnetization, scanning electron microscopy and transport measurements. Samples were sintered for 30 minutes at the following temperatures: 650° C, 700° C, 750° C, 800° C, and 850° C. It is found that the cores of these wires are almost in pure MgB2 superconducting phase, indicating that the Ti-sheath does not react with Mg or B. The superconducting transition temperature Tc decreases from 36 K to 34.2 K with the decrease of the sintering temperature from 850° C to 650° C. At 5 K and 20 K, critical current density Jc peaks up for samples sintered at 800° C, which is in sharp contrast with previously reported result that for Fe-sheathed MgB2 wires, Jc peaks up at sintering temperature of 650° C.
    Preview · Article · Apr 2010
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    H. Fang · G. Liang
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    ABSTRACT: Fe-sheathed MgB2 wires doped with C and TiC nanoparticles in the formula MgB2-xCx+yTiC (x = 0, 0.05, 0.1, 0.15, 0.2, and y = 0, 2.5 wt.%, 5 wt.%) were investigated. X-ray diffraction patterns indicate that the core materials in the wires contain small amount of Fe2B and MgO impurity phases, and the peaks shift with the variation of doping amount. It is found that the critical temperature Tc decreases with the increase of doping amount. Strong in-field current carrying capability enhancement was observed on MgB1.95C0.05+2.5 wt.% TiC.
    Preview · Article · Apr 2010
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    ABSTRACT: The effects of thermal neutron irradiation and excess oxygen on the properties of Ti-sheathed MgB<sub>2</sub> wires were investigated separately in this paper. No significant influence was observed when thermal neutron irradiation with fluence levels of 1.23 times 10<sup>14</sup> and 5.75 times 10<sup>14</sup> cm<sup>-2</sup> were applied on the sample, while fluence level of 3.16 times 10<sup>15</sup> cm<sup>-2</sup> provided a strong suppression of in-field critical current density. Excess oxygen in sample preparation process had negative effect on the properties of the MgB<sub>2</sub> wires. The samples prepared in air possessed lower critical temperature and in-field current carrying capability in comparison with the sample prepared in glove box.
    Full-text · Article · Jul 2009 · IEEE Transactions on Applied Superconductivity
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    Hui Fang · M. Alessandrini · C. Hoyt · G. Liang · B. Lv · K. Salama
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    ABSTRACT: Ti-sheathed MgB<sub>2</sub> wires doped with different amount of TiC nanoparticles were investigated. X-ray diffraction pattern suggested the existence of TiC<sub>0.59</sub> phase and carbon incorporation into MgB<sub>2</sub> lattice to form Mg(B<sub>1-x</sub>C<sub>x</sub>)<sub>2</sub>. Strong enhancement of in-field current carrying capability was observed on 2.5% TiC doped sample. The temperature effect was also studied. It was found that 850<sup>deg</sup>C was the optimized annealing temperature.
    Full-text · Article · Jul 2009 · IEEE Transactions on Applied Superconductivity
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    G Liang · X Liao · G Du · J Chen
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    ABSTRACT: Three precursor amino acids and adenosine triphosphate (ATP) are necessary for fermentative production of glutathione. In this study, our aims were to develop a strategy to enhance glutathione production by adding three precursor amino acids coupled with ATP in high cell density (HCD) cultivation of Candida utilis. A high-glutathione yeast strain, C. utilis WSH 02-08, was used in this study. Whole fermentative process for glutathione production was divided into two phases of cell growth and glutathione synthesis. Cells concentration was increased by HCD cultivation. Meanwhile, intracellular glutathione content was enhanced by the addition of three precursor amino acids. Concentrations of three precursor amino acids added at stationary phase were optimized by response surface methodology. Moreover, the addition of ATP 15 h after the addition of the three amino acids can further enhance glutathione production. Based on aforementioned phenomenon, a strategy of adding three precursor amino acids coupled with ATP was developed to enhance glutathione production. Without the addition of three precursor amino acids and the ATP, a total glutathione of 1123 mg l(-1) was achieved after 60-h cultivation. In comparison, addition of three precursor amino acid counterparts resulted in a total glutathione of 1841 mg l(-1). Moreover, by adding amino acids combined with ATP, a total glutathione of 2043 mg l(-1) was achieved after 72-h cultivation, increased by 81.9% and 11%, respectively, as compared with the control and the one without ATP addition. This is the first report on investigating changes of the intracellular three precursor amino acids and ATP, and gamma-glutamylcysteine synthase activity in HCD cultivation of C. utilis for glutathione production. A strategy of combining addition of three precursor amino acids with ATP was developed to enhance glutathione production in C. utilis.
    Preview · Article · Nov 2008 · Journal of Applied Microbiology
  • Y Jiang · P Xie · J Chen · G Liang
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    ABSTRACT: Gel filtration chromatography, ultra-filtration, and solid-phase extraction silica gel clean-up were evaluated for their ability to remove microcystins selectively from extracts of cyanobacteria Spirulina samples after using the reversed-phase octadecylsilyl ODS cartridge for subsequent analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The reversed-phase ODS cartridge/silica gel combination were effective and the optimal wash and elution conditions were: H(2)O (wash), 20% methanol in water (wash), and 90% methanol in water (elution) for the reversed-phase ODS cartridge, followed by 80% methanol in water elution in the silica gel cartridge. The presence of microcystins in 36 kinds of cyanobacteria Spirulina health food samples obtained from various retail outlets in China were detected by LC-MS/MS, and 34 samples (94%) contained microcystins ranging from 2 to 163 ng g(-1) (mean = 14 +/- 27 ng g(-1)), which were significantly lower than microcystins present in blue green alga products previously reported. MC-RR - which contains two molecules of arginine (R) - (in 94.4% samples) was the predominant microcystin, followed by MC-LR - where L is leucine - (30.6%) and MC-YR - where Y is tyrose - (27.8%). The possible potential health risks from chronic exposure to microcystins from contaminated cyanobacteria Spirulina health food should not be ignored, even if the toxin concentrations were low. The method presented herein is proposed to detect microcystins present in commercial cyanobacteria Spirulina samples.
    No preview · Article · Aug 2008 · Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment
  • G. Liang · F. Yen
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    ABSTRACT: The magnetic structure of mixed valence-Kondo-heavy fermion series Ce (Mn1-x Cux)2 Si2 (0≤x≤1) is reported. The magnetic susceptibility results indicate that for 0≤x≤0.3, Mn moments are antiferromagnetically (AFM) ordered and the Neel temperature TN decreases rapidly with decreasing x. For 0.4≤x≤0.7, ferromagnetic (FM) phase is observed below 140 K and both the ordering temperature Tc and Curie-Weiss temperature θp decrease with increasing x, showing the weakening of in-plane FM magnetic coupling between Mn moments due to the substitution of Mn by nonmagnetic Cu. For 0.8≤x≤1, samples exhibit only paramagnetic behavior. The types of magnetic order in this series are basically consistent with the criterion that FM (AFM) phase is favored when intralayer Mn-Mn spacing R Mn-Mn a is greater (smaller) than a critical value of 2.865 Å. A magnetic phase diagram is constructed for this compound series.
    No preview · Article · Apr 2008 · Journal of Applied Physics
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    S Li · P Xie · J Xu · L Li · G Liang · L Zheng

    Full-text · Article · Oct 2007 · Bulletin of Environmental Contamination and Toxicology
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    ABSTRACT: The properties of MgB<sub>2</sub> have the potential to make this material a viable solution for applications in which temperature, costs or weight are considered relevant constraints. In order to realize large scale applications, it is important to investigate the material, but also the winding process for MgB<sub>2</sub> wires and tapes. In the literature small coils have already demonstrated central magnetic flux density above 2 Tesla, overcoming common winding problems related to MgB<sub>2</sub> wires. In this current research, efforts are being made in order to improve the performance of solenoid coils, which are of particular interest for many applications, e.g. for space propulsion systems such as the VASIMR engine. A number of coils with MgB<sub>2</sub> tapes are being built. In this paper we present results of the test of a 14 cm bore solenoid wound with 400 meters of multifilament, copper stabilized tape. The magnet was tested in a cryocooled vacuum chamber and it reached 175 A at 16 K with a central B<sub>0</sub> of 1 Tesla.
    Full-text · Article · Jul 2007 · IEEE Transactions on Applied Superconductivity
  • G. Liang · F. Yen · S. Keith · M. Croft
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    ABSTRACT: Temperature and field-dependent magnetization measurements on polycrystalline CeMnCuSi2 reveal that the Mn moments in this compound exhibit ordering with a ferromagnetic (FM) component ordered instead of the previously reported purely antiferromagnetic (AFM) ordering. The FM ordering temperature, Tc, is about 120K and almost unchanged with external fields up to 50kOe. Furthermore, an AFM component (such as in a canted spin structure) is observed to be present in this phase, and its orientation is modified rapidly by the external magnetic field. The Ce L3-edge X-ray absorption result shows that the Ce ions in this compound are nearly trivalent, very similar to that in the heavy fermion system CeCu2Si2. Large thermomagnetic irreversibility is observed between the zero-field-cooled (ZFC) and field-cooled (FC) M(T) curves below Tc indicating strong magnetocrystalline anisotropy in the ordered phase. At 5K, a metamagnetic-type transition is observed to occur at a critical field of about 8kOe, and this critical field decreases with increasing temperature. The FM ordering of the Mn moments in CeMnCuSi2 is consistent with the value of the intralayer Mn–Mn distance RaMn–Mn=2.890Å, which is greater than the critical value 2.865Å for FM ordering. Finally, a magnetic phase diagram is constructed for CeMnCuSi2.
    No preview · Article · Jul 2007 · Journal of Magnetism and Magnetic Materials
  • G Liang · H Fang · Z P Luo · C Hoyt · F Yen · S Guchhait · B Lv · J T Markert
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    ABSTRACT: Ti-sheathed MgB2 wires doped with nanosize crystalline-SiC up to a concentration of 15 wt% SiC have been fabricated, and the effects of the SiC doping on the critical current density (Jc) and other superconducting properties studied. In contrast with the previously reported results that nano-SiC doping with a doping range below 16 wt% usually enhances Jc, particularly at higher fields, our measurements show that SiC doping decreases Jc over almost the whole field range from 0 to 7.3 T at all temperatures. Furthermore, it is found that the degradation of Jc becomes stronger at higher SiC doping levels, which is also in sharp contrast with the reported results that Jc is usually optimized at doping levels near 10 wt% SiC. Our results indicate that these negative effects on Jc could be attributed to the absence of significant effective pinning centres (mainly Mg2Si) due to the high chemical stability of the crystalline-SiC particles.
    No preview · Article · Jun 2007 · Superconductor Science and Technology
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    ABSTRACT: Ti-sheathed monocore MgB2 wires with improved magnetic critical current density (Jc) have been fabricated by in situ powder-in-tube (PIT) method and characterized by magnetization, X-ray diffraction, scanning electron microscopy and electrical resistivity measurements. For the best wire, the magnetic Jc values at 5 K and fields of 2 T, 5 T, and 8 T are 4.1 × 105 A/cm2, 7.8 × 104 A/cm2, and 1.4 × 104 A/cm2, respectively. At 20 K and fields of 0.5 T and 3 T, the Jc values are about 3.6 × 105 A/cm2 and 3.1 × 104 A/cm2, respectively, which are much higher than those of the Fe-sheathed mono-core MgB2 wires fabricated with the same in situ PIT process and under the same fabricating conditions. It appears that the overall Jc for the average Ti-sheathed wires is comparable to that of the Fe-sheathed wires. Our X-ray diffraction and scanning electron microscopy analysis indicates that Jc in the Ti-sheathed MgB2 wires can be strongly suppressed by MgO impurities and micro-cracks.
    Full-text · Article · Jun 2007 · Physica C Superconductivity
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    S Li · P Xie · J Xu · X Zhang · J Qin · L Zheng · G Liang

    Full-text · Article · May 2007 · Bulletin of Environmental Contamination and Toxicology

Publication Stats

938 Citations
224.80 Total Impact Points

Institutions

  • 1993-2012
    • Sam Houston State University
      • Department of Physics
      Huntsville, Texas, United States
  • 2008
    • Jiangnan University
      • School of Biotechnology
      Wu-hsi, Jiangsu Sheng, China
  • 2007-2008
    • Chinese Academy of Sciences
      • Institute of Hydrobiology
      Peping, Beijing, China
  • 2006
    • Peking Union Medical College Hospital
      Peping, Beijing, China
  • 1987-1991
    • Rutgers, The State University of New Jersey
      • • Department of Physics
      • • Department Physics and Astronomy
      Нью-Брансуик, New Jersey, United States