用DEA方法测算产出弹性

本文主要讨论并给出了把ＤＥＡ模型Ｃ２ＧＳ２用于测算产出的弧弹性的方法。     

Pressure-responsive AuNPs/Polyacrylamide Nanocomposite Hydrogel with Highly Stable and Tunable Electrochemiluminescence Performances

Synergistically taking the advantage of distinctive porous matrix, luminophore and functional nanoparticles, we prepared functional nanocomposite hydrogel combining the hydrophilic three-dimensional network of hydrogels as matrix for the adsorption of luminophore, Ru(bpy)₃²⁺, and in situ grown gold nanoparticles (AuNPs) as the conductive. Interestingly, the designed nanocomposite hydrogel shows external pressure resposnsive properties, which precisely tune the distance between the AuNPs becomes shorter, resulting in a remarkable amplification of electrochemiluminescence (ECL) signals. Additionally, differing from the poor stability of conventional ECL, uniform dispersion of the Ru(bpy)₃²⁺ over nanocomposite hydrogel significantly enhanced the long term stability of ECL.     

海藻多糖的组成及结构光谱分析

海藻多糖具有抗凝血等多种生物活性,其活性与多糖的组成结构有关。本文对近年来红藻、褐藻及少量绿藻多糖的单糖组成及含量研究以及FT-IR和12^C NMR两种主要光谱手段对多糖结构研究的结果进行了介绍。     

Acoustic absorbers at low frequency based on split-tube metamaterials

The remarkable properties of acoustic metamaterials have attracted massive researches and applications, especially on low-frequency sound absorptions. Currently, most of the acoustic metamaterial absorbers employ resonances in plastic cavities, and their structural strengths are important in many circumstances, especially in harsh environment. However, studies of metamaterials including this point are very scarce. Here, we propose an acoustic metamaterial for low-frequency (<500 Hz) absorptions, composed of three nested square split tubes with inverted opening directions. The efficiency of the absorber is investigated both numerically and experimentally, and absorptions at the peeks are found to exceed 90% and the frequency can be effectively adjusted by tuning its geometric parameters. We further test its yield strength under compression and confirm its buckling behavior happens from the outmost layer. This tunable acoustic metamaterial with a fairly good mechanical strength may lead to broad applications in noise reduction.     

高压捕获翼前缘型线优化和分析

为分析翼前缘形状变化对高压捕获翼构型气动性能的影响,基于一种锥体组合捕获翼概念构型,采用幂次函数和余弦函数组合形式对翼前缘型线进行了参数化设计,在比较了多项式和径向基函数两种代理模型的拟合精度基础上,以飞行马赫数7,飞行攻角0° 为计算条件,结合使用均匀实验设计方法、计算流体力学、径向基函数代理模型方法和遗传算法,选择升阻比最大化为目标开展了数值优化,最后基于优化结果进行了单参数的灵敏度分析. 优化结果表明,相对于基准外形而言,优化后构型升力系数增大了约8.1%,阻力系数减小了约12.2%,升阻比提高了约23.4%. 此外,灵敏度分析结果表明升阻比与5 个设计参数均呈非线性关系,其中展向角度对升阻比影响最大,其次为幂次曲线的比例参数,其余3 个参数对升阻比的影响相对较弱.      

乘波体压缩面变化对其气动性能影响分析

乘波体是一种利用激波包裹特性获得高升阻比的高速飞行器构型.已有研究中,乘波体气动性能的改善主要依赖于给定源流场条件下的前缘型线优化.本文采用数值优化和计算流体力学模拟为主要手段分析了乘波体压缩面变化对其气动性能的影响,以期有效拓展乘波体的设计空间.主要内容如下:首先给出了一种基于表面局部变形的乘波体设计方法.其次结合运用增量修正参数化方法、计算流体力学分析和微分演化算法构造了乘波体压缩面外形气动优化设计流程,以一种椭圆锥形流场生成的乘波体作为基准构型开展了无黏优化.之后从优化结果中选择升阻比递增的6个典型构型进行前缘钝化处理后,基于N-S方程对其气动性能进行了评估.最后综合依据无黏/黏性计算结果分析了乘波体压缩面变化对其气动性能的影响.结果表明该部分形状的改变对乘波体气动性能影响十分明显,在升力面积不变的条件下,乘波体压缩面形状变化可导致其升阻比出现成倍变化,即使在升力不减条件下,升阻比较基准构型也可获得超过14%的提升.此外,还可导致乘波体相对压心系数出现明显偏移.     

铜在离子选择性涂层下腐蚀行为的阻抗谱研究

用电化学交流阻抗技术研究了涂装不同离子造反性涂层的铜电极在３％ＮａＣｌ溶液中的腐蚀行为，悄同涂装体系的阻抗谱特征，建立了相应的等 电路模型，由阻抗数据解析的结果，讨论了不同离子选择性涂层对铜的防蚀性能。     

Measurements of Building Construction Materials at Ka-Band

Millimeter waves is expected to be used for indoor broadband wireless access for its rich frequency spectrum resources. To implement the indoor MMW wireless system, it is important to know its propagation characteristics in building, which are governed by the transmission properties of construction materials. This paper focuses on the measurements of reflection characteristics and refractive indices of some interior construction materials (such as glass, brick, plasterboard, silencing board, etc.) at Ka–band. The free–space reflection method was used to measure the reflection and transmission coefficients. Then the complex refractive indices of various materials could be calculated by using the Fresnel's formula.     

Polydiacetylene-based poly-ion complex enabling aggregation-induced emission and photodynamic therapy dual turn-on for on-demand pathogenic bacteria elimination

Science China Chemistry - Poly-ion complex (PIC) integrating non-antibiotic theranostics holds great promise in the combat against drug-resistant bacteria. Photosensitizers with aggregation-induced...