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Now showing items 145 - 160 of 213

  • Developing signal processing method for recognizing defects in metal samples based on heat diffusion properties in sonic infrared image sequences

    Zeng, Zhi   Tao, Ning   Feng, Lichun   Zhang, Cunlin   Han, Xiaoyan  

    In sonic infrared (SonicIR) imaging, heat is generated in defect areas during the sonic pulse; the heat appears bright in SonicIR images as the indication of a defect. However, in practical applications of SonicIR, there are lots of disturbing bright areas in infrared images, such as heat reflection and paint problem. When crack size is small, the generated heat appears not bright enough to be recognizable. Based on heat diffusion properties in the one-dimensional temporal and two-dimensional spatial domain, a method is developed to automatically recognize defect signals from SonicIR image sequences. The algorithm is verified with the SonicIR image sequences of 100 metal plates which may have different thickness, materials, or crack sizes. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
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  • Screening for gamma-Nonalactone in the Headspace of Freshly Cooked Non-Scented Rice Using SPME/GC-O and SPME/GC-MS

    Zeng, Zhi   Zhang, Han   Zhang, Tao   Tamogami, Shigeru   Chen, Jie Yu  

    The determination of gamma-nonalactone as one of the important odor-active compounds in freshly cooked non-scented rice is reported. It was evaluated by gas chromatography-olfactometry (GC-O) analysis and identified by gas chromatography-mass spectrometry (GC-MS) analysis in the headspace above the freshly cooked non-scented rice samples extracted by using a modified headspace solid-phase microextraction (SPME) method. This component had a mass spectrum with a characteristic ion peak at m/z 85 (100%) and a linear retention index (RI) of 2,023 on a DB Wax column, consistent with those of an authentic sample of gamma-nonalactone. The odor characterization of a strong, sweet, coconut-like aroma of this compound was also validated by GC-O comparison with the authentic compound.
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  • Absence of phase transformation of dense anthracene from Raman scattering

    Xiao, Ling-Ping   Zeng, Zhi   Chen, Xiao-Jia  

    The high pressure vibrational properties of anthracene are investigated by using Raman scattering techniques in diamond anvil cells up to 7.1GPa at room temperature. We present a detailed analysis of the normal vibrational modes of anthracene along with assignments of both symmetry and molecular motion. Our results demonstrate that almost all the modes shift toward higher frequencies and some peaks are broadened with increasing pressure. The smooth evolution of peaks corresponding to first and second nearest neighbor shell molecules with pressure rules out the possible existence of phase transformation. The mode Gruneisen parameters are obtained over the wide frequency range and relatively high pressure range.
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  • Multi-Objective Optimum Design of High-Speed Backplane Connector Using Particle Swarm Optimization

    Yu, Wenjie   Zeng, Zhi   Peng, Bei   Yan, Shuo   Huang, Yueshuang   Jiang, Hai   Li, Xunbo   Fan, Tao  

    This paper outlines a new procedure for computer modeling and optimum design for the dynamic mechanical and electrical study of a high-speed backplane connector, which is a key electrical interconnection technology in large communications equipment, ultra-high performance servers, supercomputers, industrial computers, high-end storage devices, and so on. The optimum structure design of contact pairs is important for a backplane connector in meeting multiple challenges in terms of minimizing the maximum insertion force and the contact resistance. Current optimization schemes, such as the quadrature method, are relatively complex. Therefore, we designed the connector contact pairs for simultaneously obtaining the proper insertion force and the contact resistance through a multi-objective particle swarm optimization (MCDPSO) method with simpler settings and faster convergence speed. In this paper, the required insertion force was minimized during the entire process, and the minimum contact resistance was maintained after insertion. To this end, an MCDPSO algorithm was proposed for the connector design. A dynamic weight coefficient was developed to calculate the interval values of the reserved solutions for the selection of the operator, and an external archive update based on roulette wheel selection and gbest selection strategies was developed to increase the diversity of the solutions. A set of optimal structure solutions of the contact pairs was obtained for the subsequent design optimization. The feasibility and effectiveness of the proposed method were verified by comparing with the results from ANSYS finite element simulation.
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  • Specified value based defect depth prediction using pulsed thermography

    Zeng, Zhi   Tao, Ning   Feng, Lichun   Zhang, Cunlin  

    Several methods have been reported in the literature using pulsed thermography for quantitative measurement of defect depth or sample thickness. In this paper, based on the analysis of a theoretical one-dimensional solution of pulsed thermography, a new method was proposed to first multiply the original temperature decay with square root of the corresponding time to obtain a monotonically increasing function f. A specific time was obtained by setting f equals to a predefined value, the theoretical model shows that the obtained specific time has linear relation with square of defect depth, which was verified with the experimental results of one aluminum and one glass fiber reinforced polymer specimen machined with six flat-bottom wedges as simulated defects. This linearity can be used for defect depth prediction in pulsed thermography. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737784]
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  • From 1D chain to 3D network:A theoretical study on TiO2 low dimensional structures

    Guo, Ling-ju   Zeng, Zhi   He, Tao  

    We have performed a systematic study on a series of low dimensional TiO2 nanostructures under density functional theory methods. The geometries, stabilities, growth mechanism, and electronic structures of 1D chain, 2D ring, 2D ring array, and 3D network of TiO2 nanostructures are analyzed. Based on the Ti2O4 building unit, a series of 1D TiO2 nano chains and rings can be built. Furthermore, 2D ring array and 3D network nanostructures can be constructed from 1D chains and rings. Among non-periodic TiO2 chain and ring structures, one series of ring structures is found to be more stable. The geometry model of the 2D ring arrays and 3D network structures in this work has provided a theoretical understanding on the structure information in experiments. Based on these semiconductive low dimensional structures, moreover, it can help to understand and design new hierarchical TiO2 nanostructure in the future. (C) 2015 AIP Publishing LLC.
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  • Effect of mini-tyrosyl-tRNA synthetase/mini-tryptophanyl-tRNA synthetase on ischemic angiogenesis in rats: proliferation and migration of endothelial cells

    Chen, Yu-cheng   Zeng, Zhi   Liu, Wei-qiang   Jiang, Xiao-fei   Liu, Rui   Qiang, Ou   Li, Xian  

    The purpose of this study was to determine the mechanism of mini-tyrosyl-tRNA synthetase/mini-tryptophanyl-tRNA synthetase (mini-TyrRS/mini-TrpRS) on ischemic angiogenesis in rats with acute myocardial infarction and proliferation, migration, potential signaling pathways of rat coronary venular endothelial cells (RCVECs). The effects of mini-TyrRS/mini-TrpRS on RCVECs proliferation were evaluated using the MTT colorimetric assay. Cell migration was assayed using a modified Boyden chamber technique. The potential involvement of Erk and PI3K signaling pathways was explored using selective chemical inhibitor or Western-blot analysis. Left coronary artery ligation was used to establish the model of acute myocardial infarction in rats (Sprague-Dawley male rats, 200-250 g, 2-3 months old), 20 mu l of mini-TyrRS, mini-TrpRS, or PBS (vehicle) was injected subcutaneously every 12 h. The rats were randomly divided into four experimental groups: sham operated group; coronary artery ligation (CAL); CAL + mini-TyrRS (20 mu l, twice daily, 600 mu g kg(-1) day(-1)); and CAL + mini-TrpRS (20 mu l, twice daily, 600 mu g kg(-1) day(-1)). The experiment was carried out at four time points on the 3rd, 7th, 14th, and 28th day after ligation. To determine whether mini-TyrRS/mini-TrpRS affected the angiogenesis activity of rats with myocardial infarction, we measured the myocardial infarction size by TTC staining, and microvessel density (MVD) was determined by CD34 staining. The results show that proliferation and migration in RCVECs could be promoted by mini-TyrRS at concentrations of 1-100 mu g/ml, and inhibited by mini-TrpRS. Phospho-PI3-kinase and Erk expression increased significantly when mini-TyrRS was added, but could be attenuated by mini-TrpRS. Compared to the CAL group, the myocardial infarction size of the mini-TyrRS group at the 3rd, 7th, 14th, and 28th day were decreased, while mini-TrpRS increased, but only in days 14 and 28 was there a significant difference. Except that, the microvessel density of RCVECs was promoted in mini-TyrRS group but inhibited in the mini-TrpRS group. These results indicated that angiogenesis could be either stimulated by mini-TyrRS or inhibited by mini-TrpRS.
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  • High‐pressure Raman spectroscopy of CeOCl: Observation of the isostructural phase transition

    Zhang, Leilei   Cheng, Ya   Wang, Xianlong   Hu, Qiwei   Zeng, Zhi   He, Duanwei   Lei, Li  

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  • Mechanical Properties Optimization of Poly-Ether-Ether-Ketone via Fused Deposition Modeling

    Deng, Xiaohu   Zeng, Zhi   Peng, Bei   Yan, Shuo   Ke, Wenchao  

    Compared to the common selective laser sintering (SLS) manufacturing method, fused deposition modeling (FDM) seems to be an economical and efficient three-dimensional (3D) printing method for high temperature polymer materials in medical applications. In this work, a customized FDM system was developed for polyether-ether-ketone (PEEK) materials printing. The effects of printing speed, layer thickness, printing temperature and filling ratio on tensile properties were analyzed by the orthogonal test of four factors and three levels. Optimal tensile properties of the PEEK specimens were observed at a printing speed of 60 mm/s, layer thickness of 0.2 mm, temperature of 370 degrees C and filling ratio of 40%. Furthermore, the impact and bending tests were conducted under optimized conditions and the results demonstrated that the printed PEEK specimens have appropriate mechanical properties.
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  • Suppressive Effects of Ursolic Acid on Human Endometriotic Stromal Cells Survival

    Li, Jingjie   Zeng, Zhi   Chang, Yajie   Li, Manchao   Wu, Qiuli   Chen, Pan   Liang, Xiaoyan  

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  • Analysis of flavor volatiles of glutinous rice during cooking by combined gas chromatography-mass spectrometry with modified headspace solid-phase microextraction method

    Zeng, Zhi   Zhang, Han   Zhang, Tao   Tamogami, Shigeru   Chen, Jie Yu  

    A combined gas chromatography-mass spectrometry (GC-MS) with modified headspace solid-phase microextraction (SPME) method, with the headspace inside a designed sampling apparatus instead of in a vial, has been employed for the analysis of the flavor volatiles of glutinous rice during cooking. All of the free flavor volatiles, the bound flavor components and the compounds formed by the thermal decomposition of the non-volatile constituents existing in rice could be liberated during the cooking process. Therefore, a broad range of the flavor volatiles of glutinous rice during cooking could be extracted, concentrated and identified in a single headspace SPME/GC-MS run. Altogether, 96 volatile compounds were identified, of which 27 components have not been previously reported in rice. A total of 86, 90 and 94 peaks, respectively, were assigned to Tatsukomochi, Kinunohada and Miyakoganemochi during cooking. The volatile components identified in the three glutinous rice cultivars during cooking belong to the chemical classes of aldehydes, ketones, alcohols and heterocyclic compounds, as well as fatty acids and esters, phenolic compounds, hydrocarbons, etc. (C) 2009 Elsevier Inc. All rights reserved.
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  • The thermodynamic and kinetic properties of hydrogen dimers on graphene RID G-5770-2010 RID A-4522-2011

    Huang, Liang Feng   Ni, Mei Yan   Li, Yong Gang   Zhou, Wang Huai   Zheng, Xiao Hong   Guo, Ling Ju   Zeng, Zhi  

    The thermodynamic and kinetic properties of hydrogen adatoms on graphene are important to the materials and devices based on hydrogenated graphene. Hydrogen dimers on graphene with coverages varying from 0.040 to 0.111 ML (1.0 ML = 3.8 x 10(15)cm(-2)) were considered in this report. The thermodynamic and kinetic properties of H, D and T dimers were studied by ab initio simulations. The vibrational zero-point energy corrections were found to be not negligible in kinetics, varying from 0.038 (0.028, 0.017) to 0.257 (0.187, 0.157) eV for H (D, T) dimers. The isotope effect exhibits as that the kinetic mobility of a hydrogen dimer decreases with increasing the hydrogen mass. The simulated thermal desorption spectra with the heating rate alpha = 1.0 K/s were quite close to experimental measurements. The effect of the interaction between hydrogen dimers on their thermodynamic and kinetic properties was analyzed in detail. (C) 2011 Elsevier B.V. All rights reserved.
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  • Arbitrary cylinder color model for the codebook based background subtraction

    Zeng, Zhi   Jia, Jianyuan  

    The codebook background subtraction approach is widely used in computer vision applications. One of its distinguished features is the cylinder color model used to cope with illumination changes. The performances of this approach depends strongly on the color model. However, we have found this color model is valid only if the spectrum components of the light source change in the same proportion. In fact, this is not true in many practical cases. In these cases, the performances of the approach would be degraded significantly. To tackle this problem, we propose an arbitrary cylinder color model with a highly efficient updating strategy. This model uses cylinders whose axes need not going through the origin, so that the cylinder color model is extended to much more general cases. Experimental results show that, with no loss of real-time performance, the proposed model reduces the wrong classification rate of the cylinder color model by more than fifty percent. (C) 2014 Optical Society of America
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  • The instability of S vacancies in Cu2ZnSnS4

    Zhang, Xiaoli   Han, Miaomiao   Zeng, Zhi   Lin, Hai Qing  

    The electronic structures of the possible charge states of vacancies in the earth-abundant solar cell absorber material Cu2ZnSnS4 (CZTS) are investigated using screened-exchange hybrid density functional theory. We find that all the charge states of anionic S vacancies (VS) are not stable because VS rehybridizes with the nearest neighbor Sn atom, reducing the valence of the Sn atom. Therefore, there is no charge transition level for VS. Instead, all the charge states of cation vacancies are stable. The copper and zinc vacancies show delocalized features which create shallow charge transition levels, while the tin vacancy shows localized feature which creates deep charge transition levels within the band gap and acts as a recombination center in CZTS.
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  • Identification of a Multi-RNA-Type-Based Signature for Recurrence-Free Survival Prediction in Patients with Uterine Corpus Endometrial Carcinoma

    Wang, Peizhi   Zeng, Zhi   Shen, Xiaoting   Tian, Xiaohui   Ye, Qingjian  

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  • Organ dose conversion coefficients for external photon irradiation using the Chinese voxel phantom (CVP)

    Li, Junli   Qiu, Rui   Zhang, Zhan   Liu, Liye   Zeng, Zhi   Bi, Lei   Li, Wenqian  

    A set of conversion coefficients from kerma free-in-air to the organ absorbed dose are presented for external monoenergetic photon beams from 10 keV to 10 MeV based on a whole-body, Chinese adult male voxel phantom. This computational phantom, called the Chinese voxel phantom (CVP), including totally 23 organs, was developed from magnetic resonance imaging of a young healthy Chinese man at a resolution of 2 x 2 mm. Compared with the ICRP Reference Man, more than half of the organs or tissues in the CVP show mass differences of more than 20. Monte Carlo simulations with MCNP code were carried out to calculate the organ dose conversion coefficients. Irradiation conditions include anterior-posterior, posterior-anterior (PA), right-lateral, left-lateral, rotational and isotropic geometries. Organ dose conversion coefficients from this study are compared with the data from the Asian voxel phantoms Visible Chinese Human and KORMAN. These data sets agree with each other within 10% for photon energy > 5 MeV. However, discrepancies of 34-63% were observed for organs of the alimentary tract, such as the oesophagus and stomach, those of the urinary system, such as the bladder wall and thyroid, especially at low photon energy range and PA geometry. These results suggest that the anatomical variation within the Chinese population, as represented by these adult male voxel phantoms, can lead to uncertainties when a standard phantom is used for the entire population.
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