Highly scalable ZIF‐based mixed‐matrix hollow fiber membranes for advanced hydrocarbon separations

ZIF‐8/6FDA‐DAM, a proven mixed‐matrix material that demonstrated remarkably enhanced C₃H₆/C₃H₈ selectivity in dense film geometry, was extended to scalable hollow fiber geometry in the current work. We successfully formed dual‐layer ZIF‐8/6FDA‐DAM mixed‐matrix hollow fiber membranes with ZIF‐8 nanoparticle loading up to 30 wt % using the conventional dry‐jet/wet‐quench fiber spinning technique. The mixed‐matrix hollow fibers showed significantly enhanced C₃H₆/C₃H₈ selectivity that was consistent with mixed‐matrix dense films. Critical variables controlling successful formation of mixed‐matrix hollow fiber membranes with desirable morphology and attractive transport properties were discussed. Furthermore, the effects of coating materials on selectivity recovery of partially defective fibers were investigated. To our best knowledge, this is the first article reporting successful formation of high‐loading mixed‐matrix hollow fiber membranes with significantly enhanced selectivity for separation of condensable olefin/paraffin mixtures. Therefore, it represents a major step in the research area of advanced mixed‐matrix membranes. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2625–2635, 2014     

阀门执行机构的PLC闭环控制方法

为了有效避免响应死区控制回路产生振动的现象,提出一种考虑响应死区的阀门执行机构PLC闭环控制方法。分析阀门执行机构的工作原理,在响应死区条件下,构建动态数学模型,通过分析调节阀门和压力之间的关系得到传递函数。同时通过将模糊滑模控制和PID控制有效集合,构建一种增量式模糊控制器,引入改进遗传算法获取智能优化控制策略,最终实现阀门执行机构PLC闭环控制。实验测试表明,所提方法具有较好的控制性能,能够对系统的超调性及时处理,并且相应的阀门开度高于20%,可以有效满足阀门执行机构PLC工作需求。     

Preparation and characterization of branched polyesteramide/mix rare earth oxides composites

Branched polyester amide containing various amount of mix rare earth oxides (RE₂O₃) were synthesized by in-situ solution condensation of AB₂ monomer synthesized based on the reaction between maleic anhydride and diethanolamine (DEA). The effect of AB₂ monomer self-polycondensation on the RE₂O₃ surface and the properties of synthesized composites were investigated by using Fourier-transform infrared spectra (FT-IR), ultraviolet–visible absorption spectra (UV–vis), X-ray photoelectron spectroscopy, scanning electron microscopy, thermogravimetric analysis and viscosity determination. AB₂ monomer can envelop RE₂O₃ particles as an organic matrix (HBPEA′) by self-polycondensation under the proposed condition. Ionization of surface of RE₂O₃ aggregates can result in the rare earth ionic (RE³⁺) and the resulting RE³⁺ might coordinate with the organic matrix. Thermal stability of branched polyesteramide can be significantly improved in presence of 5 wt% RE₂O₃, possibly due to the coordination reaction between RE₂O₃ and the active group of the organic matrix.     

黄铁矿作为锂电池正极材料的电化学性能

对天然黄铁矿进行深加工后获得平均粒径为13μm,w(Fe)、w(S)分别为45.30%、50.95%的超微细黄铁矿粉,并以高级脂肪酸盐对其进行改性,采用TG/DSC、XPS及XRD对粉体进行了表征。XRD和TG/DSC分析表明粉体主要物相为黄铁矿FeS2,表面包覆着有机改性剂;XPS分析结果表明,改性前后黄铁矿表面S分别以SO42-和[S2]2-形式存在,而Fe均以Fe3+形式存在。对粉体试样进行电化学阻抗谱、恒电流放电测试和循环伏安测试,结果表明,改性黄铁矿具有较小的电荷转移电阻和较好的导电性;常温下以0.354A电流放电,截止电压为0.5V,改性黄铁矿的放电电位平台为1.44V,放电比容量达850mAh/g,接近理论容量890mAh/g。     

Laser coarse-fine coupling scanning method by steering double prisms

Recent developments in optical communication systems have presented an emerging need for scanning and tracking dynamic targets with high accuracy. Unfortunately, conventional scanners have difficulty supplying either sufficient vision information or high scanning resolution because of the fixed optical parameters and optomechanical structure. This paper introduces a novel cascaded double-prism scanner that combines the two scanning modes of rotating and titling motions into a nested device. The analysis results show that both the vertical field angle range and the horizontal field range of the coarse scanning are no less than ±10°, with the scanning accuracy superior to 50 μrad, while the vertical field angle range and the horizontal field range of the fine scanning are, respectively, no less than 2500 μrad and 1200 μrad, with the scanning accuracy superior to 1 μrad. The scanning method not only meets the requirements of collaboratively steering the beam deviation in a large range with high accuracy but also can obtain a variety of scanning modes and trajectories, which has important engineering significance for the solution of steering a fine beam to track and position a dynamical target.     

IC制造作业调度及资源配置机制研究

考察和分析了当前流行的IC作业调度的算法模式.在此基础上,将制造系统中的作业调度回归到本原意义上,即制造资源优化配置必须保证制造步骤得以实施,得出既处理待加工硅片,也处理加工设备的双资源调度路线.结合判决式实例(Benchmark),给出IC制造领域中静态地匹配单机加工能力和加工片量的设备配置优化算法,以及动态地调度制造资源以维持工厂流水线式并行生产的作业调度方案,使之在机器运行效率、在制品数量和制造周期压缩、生产批的流程制造可预定性等方面,均取得最优化的效果.     

Nonlinear light-sheet fluorescence microscopy by photobleaching imprinting

We present a nonlinear light-sheet fluorescence microscopy (LSFM) scheme based on photobleaching imprinting. By measuring photobleaching-induced fluorescence decay, our method simultaneously achieves a large imaging field of view and a thin optical section. Furthermore, the scattered-light-induced background is significantly reduced, considerably improving image contrast. Our method is expected to expand the application field of LSFM into the optical quasi-ballistic regime, enabling studies on non-transparent biological samples.     

二次和一般三次非线性弹性系统1/2阶亚谐共振之比较

具有二次非线性弹性振动系统1/2阶亚谐共振在两个分叉频率之间有一不稳定域.研究表明,加入三次非线性弹性可以抑制不稳定性,而在一定频率范围出现跳跃现象,且两种系统发生1/2阶亚谐共振的条件在一阶近似下相同.     

高精度工频相位计研制

本文从分析典型的相位差数字化测量方法入手,对实测精度优于0.02°的工频相位计的硬件及软件机理进行了介绍,并对提高相位差测量精度的技术措施及相关电路进行了详细说明。     

椭圆形管式密封铅酸电池在内燃机车的应用

本文叙述了内燃机车起动用椭圆形管式密封铅酸电池的设计。性能测试表明起动性能良好,在机车上的使用寿命预期比原有电池提高一倍左右,且无需维护。