微观尺度下浇筑式沥青混合料超热老化机理

为了揭示浇筑式沥青混合料超热老化机理,采用傅里叶红外光谱法（FTIR）和热失重法(TG)实时追踪扫描了微观尺度下浇筑式沥青不同超热温度下分子基团以及轻质组分的变化规律,分析了超热温度下挥发和氧化对改性沥青老化的影响进程.结果表明：在超热温度下,挥发对浇筑式沥青混合料老化所起的作用明显,并且一直贯穿整个超热老化过程,而氧气浓度决定了氧化在其整个老化过程中的作用时间,在高氧气浓度下,氧化主要发生在老化前期,而老化后期轻质组分的挥发起主导作用.     

府河随州区段河流水质模拟

通过对湖北省府河随州区段河流现场调查和水质现状监测,应用系统的方法,将河流进行概化,并建立了该河段的一维水质模型,结合2008年的水文资料,应用实测资料进行模型参数的确定。经模型验证,模拟结果与该段河流的实际水质监测结果基本吻合,表明该模型具有一定的合理性和实用性。     

Block adaptive kernel principal component analysis for nonlinear process monitoring

On‐line modeling of multivariate nonlinear system based on multivariate statistical methods has been studied extensively due to its industrial requirements. In order to further improve the modeling efficiency, a fast Block Adaptive Kernel Principal Component Analysis algorithm is proposed. Comparing with the existing work, the proposed algorithm (1) does not rely on iterative computation in the calculating process, (2) combines the up‐ and downdating operations to become a single one (3) and describes the adaptation of the Gram matrix as a series of rank‐1 modification. In addition, (4) the updation of the eigenvalues and eigenvectors is of and high‐precision. The computational complexity analysis and the numerical study show that the derived strategy possesses better ability to model the time‐varying nonlinear variable interrelationships in process monitoring. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4334–4345, 2016     

Fabrication and Property of Mullite Whiskers Frameworks with an Ultrahigh Porosity by Expandable Mesocarbon Microbeads

Mullite whiskers frameworks with an ultrahigh porosity were fabricated by the vapor‐phase reaction of AlF₃, Al₂O₃, and SiO₂ and adding expandable mesocarbon microbeads (MCMB) as a pore‐forming agent. A large volume expansion of 122% for MCMB due to its layered structure occurred during the formation of mullite whiskers, resulting in the expansion of samples and high porosities of 87.7%–98.2% at 50–90 wt% MCMB contents. Perfect whiskers and a lap‐joint structure formed due to the formation of mullites through the vapor‐phase reaction. A bimodal pore structure was achieved from the spaces of the whiskers framework and burning of the expanded MCMB. High compressive strengths of 1.7 to 5.4 MPa were obtained for the porous mullite at porosities of 94.2%–87.7%, which suggested a rigid structure; these strengths at the ultrahigh porosities are attributed to the merit of the framework with high strength whiskers and their strong bonding.     

Oxidation of ZrB2–SiC‐Graphite Composites Under Low Oxygen Partial Pressures of 500 and 1500 Pa at 1800°C

The oxidation behavior of ZrB₂–SiC‐graphite composites under low oxygen partial pressures of 500 and 1500 Pa at 1800°C was investigated. The phase composition and microstructure of the oxidized scale were characterized using TEM, SEM, XRD, XPS, EDS. The analytical results indicated that a low oxygen partial pressure had a remarkable effect on the oxidation mechanism of ZrB₂–SiC‐graphite composites. When oxidized at 1500 Pa, the oxidation kinetics was controlled by the rate of oxygen diffusion into the composite. When the composite was oxidized at 500 Pa, control of the oxidation kinetics changed from the rate of oxygen diffusion to the rate of the oxidation reaction. The rate of oxidation decreased with decreasing oxygen partial pressure. Higher partial pressures of oxygen resulted in less oxidation resistance by the ZrB₂–SiC‐graphite composites.     

Multifunctional Coordination Polymer Nanoparticles Based on Allantoin: Single Peak Upconversion Emission,Drug Delivery and Cytotoxicity Study

In this work, multifunctional coordination polymer (CP) nanoparticles with strong single peak upconversion emission and high drug loading capacity were prepared via a facile solvothermal method. Various experimental parameters, such as reaction time, reaction temperature and reagent concentration were studied in detail. A series of measurements were carried out to characterize the product. Results show the CP particles with a mean diameter of approximately 80 nm can be prepared by finely selecting the preparation conditions. Strong single peak upconversion emission centering at 675 nm is observed on excitation with 980 nm laser. Drug loading and releasing experiments reveal that the CP nanospheres have a loading capacity of 200 mg/g and 50.3 % of the loaded fluorescein isothiocyanate can be released in 18 h. Cytotoxicity study displays that the CP nanospheres are biocompatible.     

In situ two-step electrochemical preparation of fluoride-free nickel-based compound film on nickel plate for supercapacitors

A nickel-based compound layer was prepared on a nickel plate by anodization in a 75 wt% H_3PO_4 solution containing NH_4F. This layer was then treated by galvanostatic charge/discharge(GCD) until a black outer layer was detached, leaving behind a film on the nickel plate as a binder-free electrode material for supercapacitors. The microstructural characterization shows that the film consists of Ni(OH)_2and NiO, and no fluoride is found in the as-obtained film. Electrochemical tests demonstrate that this fluoride-free film electrode exhibits a high capacitance of 954 F g~(-1)at 7.5 Ag~(-1), excellent rate capability(a 19.5 % capacitance reduction with the current density increasing to 120 Ag~(-1)) and cycling stability.Within 3500 cycles, the specific capacitance does not decrease, but rather increases from 840 Fg~(-1)to approximately 1092 Fg~(-1)in the first 100 cycles at 60 Ag~(-1), and remains stable until the aforementioned layer is detached.     

Performance of Sm<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>CoO<Subscript>3−<Emphasis Type="Italic">δ</Emphasis></Subscript> membrane under CO<Subscript>2</Subscript>-containing atmosphere

The permeability and stability of Sm_0.7Sr_0.3CoO_3?δ (SSCO) regarding the special requirements for carbon capture and storage (CCS) application were investigated. Pure CO₂ was used as the sweep gas at 900 °C, leading to that the oxygen permeation flux decreases by about 34 %. Several cycles of changing the sweep gas between helium and CO₂ indicate the good reversibility of this degradation. Both carbonate formation and adsorption of CO₂ on the membrane surface are responsible for the degradation of the membrane performance. The better CO₂ resistance results from the substitution of Sm for Sr due to the higher acidity of Sm₂O₃ (1.278) than that of SrO (0.978) and a discontinuous layer of carbonate.     

Ti-6Al-4V钛合金网篮组织与拉伸性能 定量关系研究

建立钛合金显微组织-拉伸性能定量关系对于组织性能的控制及优化具有重要意义。本文基于定量金相学和体视学原理,利用多元非线性回归方法建立了Ti-6Al-4V钛合金网篮组织-拉伸性能定量关系模型。模型自变量包括片状α相厚度、片状α相长宽比,因变量为合金的室温拉伸性能。经验证表明,所建立的多元回归模型对合金的拉伸性能具有较高的预测精度,说明模型的构建方法是可行的。