采用渐变与突变机制的反向人工蜂群算法

为克服人工蜂群算法容易陷入局部最优且后期收敛速度较慢的缺点,提出一种基于渐变与突变机制的反向人工蜂群算法并用于特征选择.采用反向学习策略,为每个初始解产生对应的反向解,并从所有解中选择最优的解构成初始种群,加快了收敛速度.引入渐变与突变机制,将个体按适应度大小分为渐变个体和突变个体,对它们采用不同的邻域搜索方法,避免了陷入局部最优.对比实验表明,新算法比其他特征选择算法能够得到更好的特征子集且具有更快的收敛速度.     

Flow and migration of nanoparticle in a single channel

A numerical simulation based on a combined Euler and Lagrange method is investigated in this work to simulate the flow and migration of nanoparticles in a single channel. The motion of discrete nanoparticles is determined by the Lagrangian trajectory method based on the Newton’s second law that includes the influence of the body force, various hydrodynamic forces, the Brownian motion and the thermophoresis force. The coupling of discrete particles with continuous flow is realized through the modification of the source term of the continuous equation. The results reveal the two-phase flow nature of nanoparticle suspensions and their implications to the convective heat transfer of nanofluids.     

在纵向自由薄膜凝固期内温度分布的数值分析

考虑到薄膜表面的热通量主要是来自辐射，因而采用一个依赖时间的拟二维拟线性扩散方程的Ｓｔｅｆａｎ问题（混合初边值问题）作为该问题的数学模型。用一种具有Ｃｒａｎｋ－Ｎｉｃｈｏｌｓｏｎ格式的无条件稳定的有限差分析来求解抛物型偏微分方程的定解问题。用追赶法求解离散化的三对角方程组，然后用预估校正法求解拟线性扩散方程，从而避免了示解非线性差分方程组，琥珀亚硝酸酯在纵向自由薄膜凝固期内的温度分布数值计算结果和     

Assembly-enhanced triplet-triplet annihilation upconversion in the aggregation formed by Schiff-base Pt(II) complex grafting-permethyl-β-CD and 9, 10-diphenylanthracence dimer

Water-soluble triplet sensitizer with permethyl-β-cyclodextrin (PMCD) grafting on a Schiff-base Pt (II) complex (Pt-2),was synthesized to enhance the efficiency of triplet-triplet energy transfer through hostguest complexation.DPA dimer A-2 in which two DPA carboxylate were covalently linked with an alkyl chain showed an improved triplet-triplet annihilation through both intramolecular interaction and self-aggregation. Significantly improved TTA-UC emission was observed with Pt-2 and A-2 as the donor/acceptor pair.     

Optimized design and experiment of one-dimensional omnidirectional reflector using P-wave angle domain compensated overlapping method

The optimized method of extending the omni-photonic band gap (omni-PBG) was discussed based on analyzing the P-wave reflectivity characteristics in one-dimensional (1D) periodic multilayer film. A visible omnidirectional reflector with hybrid structure was designed using P-wave compensated overlapping in angle domain. The experimental result was in good agreement with the theoretical simulation.     

Design of exponential state estimators for neural networks with mixed time delays

In this Letter, the state estimation problem is dealt with for a class of recurrent neural networks (RNNs) with mixed discrete and distributed delays. The activation functions are assumed to be neither monotonic, nor differentiable, nor bounded. We aim at designing a state estimator to estimate the neuron states, through available output measurements, such that the dynamics of the estimation error is globally exponentially stable in the presence of mixed time delays. By using the Laypunov–Krasovskii functional, a linear matrix inequality (LMI) approach is developed to establish sufficient conditions to guarantee the existence of the state estimators. We show that both the existence conditions and the explicit expression of the desired estimator can be characterized in terms of the solution to an LMI. A simulation example is exploited to show the usefulness of the derived LMI-based stability conditions.     

Sorption of Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> by Natural Biomaterial: Duck Feather

Feather fibers were modified by treatment with 5% tannic acid (TA) solution. Kinetics of the modification was investigated as a function of the reaction time. The maximum loading of TA on feather reached 8.3% after being treated by TA for 9 h. The adsorption of metal cations (Cu²⁺, Zn²⁺) by unmodified and TA-modified feather fibers was investigated as a function of fiber weight gain, temperature, and pH of the metal solution. The adsorption was enhanced at alkaline pH and ambient temperature and increased with the weight gain of TA. The maximum uptake of metal cations (Cu²⁺, 0.77 mmol/g; Zn²⁺, 0.95 mmol/g) was obtained by TA-modified feather at weight gain: 8.3%, pH 11, while at the acidic pH, the adsorption of metal cations by either unmodified or TA-modified feather was negligible. The influence of anions on the adsorption of metal cations was also studied. The uptake of Cu²⁺ from chloride was higher and faster than that from nitrate. Desorption of the metals was performed at acidic pH 2.5 for 48 h. The feather–TA–metal complexes exhibited higher stability for metal cations than the feather–metal complexes. All these experiments reveal that TA-modified feather fibers have good adsorption to metal cations and can be used as metal adsorbent in wastewater treatment.     

Effects of alcohols and counterions on the phase behavior of 1-octyl-3-methylimidazolium chloride aqueous solution

Phase behavior of ternary systems involving 1-octyl-3-methylimidazolium chloride ([C8mim]Cl), water, and different alcohols (1-hexanol, 1-octanol, 1-decanol, and 1-dodecanol) is investigated at 25 degrees C. With the use of polarized optical microscopy and small-angle X-ray scattering techniques, lyotropic lamellar phases (Lalpha) are identified in all systems, the formation of which is considered as a synergetic result of the hydrophobic force and the hydrogen-bonded network comprising an imidazolium ring, Cl-, water, and alcohols. In these Lalpha phases, alcohol molecules play important roles not only because they could partly penetrate into the palisade layer with their hydroxyl groups extruded to form the network at the aggregate interface, but also because they could partly locate themselves in the interior of the hydrophobic bilayers to twist with the alkyl chains of [C8mim]Cl. Influencing factors such as the carbon chain length and content of different alcohols on these Lalpha phases are discussed. With comparison to analogous ternary systems of [C8mim]BF4 and [C8mim]PF6, it is found that the strong interaction between counterions and alcohols favors the appearance of ordered assemblies.     

淀粉基高分子材料的研究进展

概述了近5年国内外在淀粉的化学、物理改性及其作为一种材料使用方面取得的最新研究进展.淀粉的化学改性主要介绍了淀粉的酯化、醚化、氧化、交联、接枝共聚等,而物理改性主要介绍了淀粉分别与黏土、脂肪族聚酯、聚乙烯醇以及纤维素等天然大分子的共混改性,同时还介绍了通过酸化制备淀粉纳米晶.淀粉基材料除了用于制备可生物降解塑料、吸附材...     

生物油酸酮类模化物与乙醇在HZSM-5上共裂化制备生物汽油

生物油酸类和酮类化合物具有较高的裂化活性,而使用分子蒸馏技术能将这些组分富集到蒸出馏分中,因此蒸出馏分相比原始生物油具有更好的裂化特性.为了模拟实际蒸出馏分的组成,本文将生物油模化物(羟基丙酮(HPO)、环戊酮和乙酸)进行配比混合,在固定床反应器上对其与乙醇的共裂化行为进行了研究,考察了不同反应温度和压力对混合反应物的转化率、粗汽油相的选择性和组成的影响.研究发现,当反应温度在340℃时,乙酸和乙醇的转化率分别仅为67.9%和74.4%,同时得到的油相产物中烃类含量仅为59.8%,并含有大量的含氧副产物.常压裂化同样生成了低品质的油相产物,同时油相选择性仅为10.8%.提高反应温度能促进反应物的转化,提高裂化过程中的脱氧效率,而提高反应压力对液体烃类的生成有明显的促进作用.在400℃和2MPa时,酸类和酮类都有良好的裂化表现,反应物接近完全转化,粗汽油相选择性达到31.5%,且全部由烃类组成,其中芳香烃含量高达91.5%.此外,反应后催化剂表征和稳定性测试结果表明,催化剂在较长时间反应后会失活,但通过催化剂再生能够很好地恢复催化剂活性.