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。     

Mechanics unloading analysis and experimentation of a new type of parallel biomimetic shoulder complex

The structure design for high ratio of carrying capacity to deadweight is one of the challenges for the bionic mechanism, while the problem concerning high carrying capacity has not yet be solved for the existing shoulder complex. A new type biomimetic shoulder complex, which adopts 3-PSS/S(P for prismatic pair, S for spherical pair) spherical parallel mechanism (SPM), is proposed. The static equilibrium equations of each component are established by using the vector method and the equations for constrain forces with certain load are solved. Then the constrain force on the middle limb and that on the side limbs are compared in order to verify the unloading performance of the mechanism. In addition, the prototype mechanism of the shoulder complex is developed, and the force feedback experiment is conducted to verify the static analysis, which indicates that the middle limb suffers most of the external force and the effect of mechanics unloading is achieved. The 3-PSS/S spherical parallel mechanism is presented for the shoulder complex, and the realization of mechanics unloading is benefit for the improvement of the carrying capacity of the shoulder complex.     

基于复杂网络聚类的提升机主轴系统故障诊断

针对摩擦提升机主轴系统故障耦合、特征微弱且故障样本不易获得的问题,提出一种基于复杂网络聚类的故障诊断方法。该方法从故障数据表现出社团结构的本质出发,以各数据样本为节点,样本间相似度为有权边,构建加权无向复杂网络模型。将欧氏空间的距离概念推广到样本的相似性度量上提出广义Ward距离,并以此为划分准则,采用凝聚型合并过程实现网络模型中社团的聚类,即故障样本的模式识别。对主轴系统过载、滚动轴承元件故障及减速器齿轮磨损的分析结果表明,该方法能准确对已知故障类型数据进行聚类,且在过程中不预设类别数,为收集异常数据以便未知故障的发现与诊断提供了数据支持。与多元支持向量机与快速Newman算法的对比结果表明,该方法具有更高的识别精度与效率。     

A finite element model of thermal evolution in laser micro sintering

Laser micro sintering (LMS) is a promising technique for micro-additive manufacturing. During LMS of metallic powder, the material property variation and the heat input energy profile are important to understand physical phenomena involved. This paper presents a finite element temperature distribution profile in LMS of nickel powder on 304 stainless steel substrate. The simulation considered the transition of powder-to-dense sub-model which involves effective thermal conductivity, volumetric enthalpy, and absorptance change; and a moving volumetric Gaussian distribution heat source sub-model. It is found that, for a specified cross section, the mechanism of preheating the nickel powder changes for the heat source from previous laser-irradiated substrate region to molten nickel as the laser beam approaches, while the center of molten pool slice is slightly shifted toward the reverse direction of laser scanning when the laser moves away due to the thermal accumulation effect. Simulated sintered widths showed very good agreement with experimental measurement, and relative prediction errors are below 16 % within the process window.     

基于深度学习特征匹配的铸件微小缺陷自动定位方法

针对射线实时成像检测中精密铸件微小缺陷自动定位的需要,提出一种基于深度学习特征匹配的铸件缺陷三维定位方法。模拟选择注意机制的中央-周边差算法,提出以视觉显著度为尺度,从射线图像复杂背景中检测出微小缺陷及其区域,以定义的区域中央点为待匹配点;然后,提出构造深度卷积神经网络自动提取微小缺陷区域的深度学习特征,通过深度学习特征矢量的相似度,实现在不同视角下投影图像中的同一微小缺陷点的自动匹配;最后,基于平移视差测距原理计算缺陷匹配点的三维空间坐标。实验表明,基于深度学习特征匹配的方法能够正确搜索平移前后投影图像中的同一缺陷点,以此为基础,利用视差测距原理实现了微小缺陷匹配点的自动准确定位,深度定位误差小于5.52%,能够满足对精密铸件微小缺陷智能评判的需要。     

采用内模控制理论的双馈感应风机鲁棒控制器设计

针对工程中双馈感应电机转子电流控制器参数整定的问题,提出一种利用内模控制理论设计转子电流控制器的鲁棒控制方法。首先定义内模控制的灵敏度函数和互补灵敏度函数,并推导双馈感应电机转子电流控制系统传递函数,建立了转子电流内环的内模数学模型。IMC控制器的设计以平方积分误差值和鲁棒稳定M值为准则,并与传统比例积分控制器进行比较。通过对1.5 MW双馈感应电机的MATLAB/SIMULINK仿真表明,本文方法稳态跟踪精度高、动态响应快、对模型误差和外界干扰具有较好的鲁棒性。最后在11 k W的双馈风机实验平台上验证了所提方法的有效性。     

Constitutive analysis of 6013 aluminum alloy in hot plane strain compression process considering deformation heating integrated with heat transfer

Hot plane strain compression tests of 6013 aluminum alloy were conducted at temperatures ranging from 613 to 773 K and strain rates ranging from 10^-3 to 10 s^-1. A novel model is developed to describe the temperature rise considering deformation heating integrated with heat transfer in tests. The experimental flow stress data are corrected by the proposed novel model. Based on the corrected flow stress, the modified power function constitutive model is developed considering the coupled effects of deformation temperature and strain rate on flow stress. Meanwhile, another two widely used models, temperature-compensated power function and straincompensated hyperbolic sine constitutive model, are also established for the studied 6013 aluminum alloy. Finally, the three constitutive models are compared from the aspects of accuracy, stability and efficiency. It is found that the experimental flow stress is significantly affected by the temperature rise. Furthermore, the influence of heat transfer on temperature rise cannot be ignored. When the constitutive model is established, the coupled effects of deformation temperature and strain rate on flow stress should be considered. The modified power function constitutive model is the best one in describing the flow behavior among the three models.