Construction of Constitutive Model and Strain-Rate Sensitivity Coefficient Distribution Map of Ti2AlNb

Yongqiang Zhang,Xiangyi Xue,Jingli Zhang,Shewei Xin,Hao Pan,Huamei Sun,Huiming Li 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

The hot deformation behavior of Ti–22Al–25Nb was studied by the high temperature compression over a range of temperatures (950–1050 °C) and strain rates (0.001–10 s−1) in this paper. The work-hardening (WH) and softening deformationbehaviors of Ti–22Al–25Nb were analyzed. Obvious linear decreasing regimes of WH rate curves can be found before thedynamic recrystallization (DRX) onset, which indicates WH+ DRV (dynamic recovery) stage. And WH rate decreasedsignifcantly with strain rate reduced and temperature elevated. A physically-based constitutive model was established,which can well predict the fow behavior of Ti–22Al–25Nb. Additional, strain-rate sensitivity coefcient distribution mapwas established. The higher values of m appeared at the low strain rate. When the strain rate exceeded 0.1 s−1, the values ofm were lower than 0.25.

Joint Spatial and Spectral Low-Rank Regularization for Hyperspectral Image Denoising

Xue, Jize,Zhao, Yongqiang,Liao, Wenzhi,Kong, Seong G. IEEE 2018 IEEE transactions on geoscience and remote sensing Vol.56 No.4

<P>Hyperspectral image (HSI) noise reduction is an active research topic in HSI processing due to its significance in improving the performance for object detection and classification. In this paper, we propose a joint spectral and spatial low-rank (LR) regularized method for HSI denoising, based on the assumption that the free-noise component in an observed signal can exist in latent low-dimensional structure while the noise component does not have this property. The proposed HSI denoising method not only considers the traditional LR property across the spectral domain but also leverages nonlocal LR property over the spatial domain. The main contribution of this paper is the incorporation of the low-rankness-based nonlocal similarity into sparse representation to characterize the spatial structure. Specially, the similar patches in each cluster usually contain similar sharp structure such as edges and textures; LR performed on cluster entitles to achieve a lower rank than that on the global spectral correlation. To make the proposed method more tractable and robust, we develop a variable splitting-based technique to solve the optimization problem. Experiment results on both simulated and real hyperspectral data sets demonstrate that the proposed method outperforms state-of-the-art methods with significant improvements both visually and quantitatively.</P>

Size-Dependent Thermodynamic Properties of the Reaction of Nano-ZnO with Benzoic Acid

Shuting Wang,Zixiang Cui,Yongqiang Xue 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.7

Studying the thermodynamic properties of the reaction of nanoparticle with organic substance is significant for the application of nanomaterial in organic fields. In this work, by using the reaction of nano-ZnO with different particle sizes with benzoic acid as a research system, the size-dependent standard equilibrium constant and reaction thermodynamic properties were analyzed theoretically, and the influence regularities of the particle size on the standard equilibrium constant and the reaction thermodynamic properties were studied. The excellent agreement between the experimental results and theoretical analysis shows that the particle size has remarkable influence on the standard equilibrium constant and the thermodynamic properties of the reaction; with the decrease of the particle size, the standard equilibrium constant increases, while the standard molar reaction Gibbs energy, the standard molar reaction enthalpy and the standard molar reaction entropy decrease. Furthermore, the logarithm of the standard equilibrium constant and the thermodynamic properties present linear relations with the reciprocal of the particle diameter, respectively. The theory and the influence regularities will provide useful tools to lead better and broader application of nanomaterial in organic fields.

Experimental and Theoretical Investigations of PAN Molecular Weight Increase in Precipitation Polymerization as a Function of H<SUB>2</SUB>O/DMSO Ratio

Jing Zhang,Fengjing Bu,Yongqiang Dai,Liwei Xue,Zhixian Xu,Seung-Kon Ryu,Riguang Jin 한국탄소학회 2010 Carbon Letters Vol.11 No.1

The precipitation polymerization of acrylonitrile (AN) was carried out in a mixture solution of dimethyl sulfoxide (DMSO) and water at 50~65℃ using α,α'-azobisisobutyronitrile (AIBN) as an initiator. The increased molecular weight polyacrylonitrile (PAN) was prepared with increasing the H2O/DMSO ratio from 10/90 to 80/20. The viscosity average molecular weight of H2O/DMSO solvent was 4.4 times larger than that of H2O/DMF solvent, and precipitation polymerization was accelerlated due to the far decreased chain transfer effect of DMSO. Based on the experimental results, the increased PAN molecular weight was regarded as the summation of two mechanisms: i) particle-particle aggregation and ii) particle-radical attachment. The theoretical equation derived from the mechanisms was well coincided with the experimental results showing the linear relationship between the viscosity average molecular weight and the H2O/DMSO ratio.

The Size Dependence of Dissolution Thermodynamics of Nanoparticles

Zhi-Qiang Wang,Yongqiang Xue,Zixiang Cui,Huijuan Duan,Xiao-Yan Xia 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.9

Dissolution of nanoparticles is involved in the preparation, research and application of nanomaterials, but there is a surprising difference in dissolution thermodynamics between nanoparticles and the corresponding bulk materials. In the paper, the relations of dissolution thermodynamic properties, equilibrium constant of nanoparticles, respectively, and particle size were derived by introducing interface variables and the surface chemical potential. Experimentally, the solubility of nano-barium sulfate with different average particle sizes at different temperatures were determined by the method of electrical conductivity, obtaining the influencing regularities of particle size on the dissolution thermodynamic properties and the equilibrium constant. The regularities are in accordance with the theory. The results show that there are remarkable effects of particle size of nanoparticles on the dissolution thermodynamic properties and the equilibrium constant; with the decreasing of the size of nanoparticles, the dissolution equilibrium constant increases, while the standard dissolution Gibbs free energy, the standard dissolution enthalpy and the standard dissolution entropy decrease; and the logarithm of the dissolution equilibrium constant, the standard dissolution Gibbs free energy, the standard dissolution enthalpy and the standard dissolution entropy are linearly associated with the reciprocal of particle size, respectively. This new theory provides a quantitative description of nanoparticles dissolution behavior, and has important scientific significance for understanding and predicting of thermodynamic regularity of dissolution concerned in the preparation, researches and applications of nanomaterials.

Static and Cyclic Tension Behavior of Post-Installed Rebar after Exposure to High Temperature

Qun Xie,Song Xue,Yongqiang Zhao 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.6

In order to investigate the static and cyclic tension behavior of post-installed rebar along with cement-based adhesive that is adopted after exposure to high temperature, a three-phase experimental program has been carried out and two typical embedment depths, 10d and 15dare designed. The surfaces of specimens are firstly heated up to 800oC, and then the residual strength at different temperatures of cement-based adhesive has been studied by consequent static pull-out tests. Experimental results show that the tensile strength has a significant reduction at elevated temperatures compared with that of room temperature. The cement-based adhesive has almost lost its full bond strength when the temperature exceeds 350oC. Finally, the bond performance of cement-based adhesive under cyclic loading has been further tested and analyzed. It is found that both 10d and 15d specimens have failed abruptly with rebar pull-out. The employment of long embedment depth has been verified to be an effective method to improve the bond performance of cement-based adhesive under static and cyclic loading. Static numerical investigation indicates that the bond stress distribution is not uniform along the embedment length of post-installed rebar at different temperatures of cement-based adhesive. The temperature-dependent tensile strength prediction has also been obtained based on the experimental data.

Effect of calcination atmospheres on the catalytic performance of nano-CeO2 in direct synthesis of DMC from methanol and CO2

Zixiang Cui,Jie Fan,Huijuan Duan,Junfeng Zhang,Yongqiang Xue,Yisheng Tan 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.1

Nano-CeO2 was prepared through the calcination of Ce(OH)3 precursor in different atmospheres (H2, Ar, air, O2), which was prepared by a hydrothermal method, and then used as catalysts in the direct synthesis of dimethyl carbonate (DMC) from methanol and CO2. The results indicated that the catalyst calcined in O2 (CeO2-O2) showed an optimum catalytic performance, and the yield of DMC reached to 1.304mmol/mmolcat. In addition, reaction temperature and weight of catalyst were optimized. Based on characterizations of the catalysts, the ratio of Ce(IV)/Ce(III) and Lewis acid-base property of nano-CeO2 catalyst could be adjusted through different calcination atmosphere treatment. It was determined that the higher activity of CeO2-O2 catalyst is mainly attributed to its higher ratio of Ce(IV)/Ce(III) as well as abundant and moderate intensity Lewis acid base sites.

Effects of a functional fatty acid blend on growth performance, intestinal morphology, and serum profiles in weaned piglets

Wang Huakai,Wang Yanan,Zhang Yu,Li Juntao,Mi Yihai,Xue Yongqiang,Li Jiaan,Ma Yongxi 아세아·태평양축산학회 2023 Animal Bioscience Vol.36 No.5

Objective: The objective of this study was to determine whether dietary supplementation with a functional fatty acid blend (FA) that contains 31.4% butyric acid and 4.99% mediumchain FA improve growth performance, antioxidant capacity, immunity status, and antiinflammatory ability in weaned piglets. Methods: One hundred and forty-four healthy piglets (Duroc×Landrace×Yorkshire) with an average body weight (BW) of 7.98±3.43 kg were randomly divided into three groups with six replicate pens and eight piglets per pen: Normal control (NC): a corn-soybean basal diet; FA1: a basal diet supplemented with 1,000 mg/kg of a functional FA; FA2: a basal diet supplemented with 2,000 mg/kg of a functional FA. The experiment lasted for 28 d. On d 14 and 28, one piglet in each pen from NC and FA2 groups was randomly selected for antioxidative index and immunoglobulins. On d 28, one piglet in each pen from NC and FA2 groups was randomly selected for intestinal morphology and inflammatory factor. Results: We observed that FA supplementation linearly increased (p<0.05) average daily gain and the final BW. There was higher (p<0.05) catalase on d 14, and immunoglobulin (Ig) A and IgM on d 28 in piglets supplemented with FA2 than in the NC group. Moreover, dietary FA2 reduced (p<0.05) crypt depth of ileum in piglets. The concentrations of tumor necrosis factor-α, interleukin (IL)-1β, IL-8, and IL-10 in jejunum were lower (p<0.05) in the FA2 group compared with the NC group. Conclusion: Therefore, the overall results suggests that the FA may help to improve gut health, antioxidant status, and immune parameters resulting in the improvement of growth performance.

Effects of essential oil coated with glycerol monolaurate on growth performance, intestinal morphology, and serum profiles in weaned piglets

Wang Yanan,Li Juntao,Wang Hua Kai,Mi Yihai,Xue Yongqiang,Li Jiaan,Ma Yongxi 아세아·태평양축산학회 2023 Animal Bioscience Vol.36 No.5

Objective: This study aimed to investigate the effects of essential oil coated with glycerol monolaurate (GML) on the growth performance, intestinal morphology, and serum profiles of weaned piglets. Methods: A total of 144 weaned piglets (Duroc×[Landrace×Yorkshire], average weight 8.07±3.33 kg) were randomly assigned to three groups with six replicate pens and eight piglets per pen: i) CON: a corn-soybean basal diet; ii) LEG: with 1,000 mg/kg essential oil coated with GML; and iii) HEG: with 2,000 mg/kg essential oil coated with GML. Results: Results showed that average daily gain was increased (p<0.05) linearly by essential oil coated with GML supplementation on day 14 to 28 and day 0 to 28 compared with the CON group. Dietary supplementation with HEG increased (p<0.05) total antioxidant capacity and catalase activity on day 14, and immunoglobulin A (IgA) and IgM concentration on day 28 and tended to increase IgG on day 28. In addition, the crypt depth in the jejunum was reduced (p<0.05), and villus height and villus height/crypt depth in the ileum were increased (p<0.05) in the HEG group compared with the CON group. Moreover, lower (p<0.05) concentrations of tumor necrosis factor-α, interferon-γ, interleukin-1β (IL-1β), IL-8, and IL-10 were observed in the jejunum of piglets supplemented with HEG compared with the CON group. In addition, dietary HEG tended to decrease IL-6 level in the jejunum of piglets compared with the CON group. Conclusion: Dietary essential oil coated with GML can improve growth performance of weaned piglets. Moreover, supplementing 2,000 mg/kg essential oil coated with GML was demonstrated to improve antioxidant ability, and intestinal morphology, and reduce jejunal inflammatory factor levels.