Optimal control of chaotic systems with input saturation using an input-state linearization scheme

Chaos is undesirable in many engineering applications since it causes a serious degradation of the system performance and restricts the system’s operating range. Therefore, the problem of controlling chaos has attracted intense interest in recent years. This paper proposes an approach for optimizing the control of chaotic systems with input saturation using an input-state linearization scheme. In the proposed approach, the optimal system gains are identified using the Nelder–Mead simplex algorithm. This algorithm does not require the derivatives of the cost function (or the performance index) to be optimized, and is therefore particularly applicable to problems with undifferentiable elements or discontinuities. Two numerical simulations are performed to demonstrate the feasibility and effectiveness of the proposed method.     

TiCl4 mediated Michael addition reactions of α-cyanoketene-S,S-acetals with enones

Titanium tetrachloride promoted Michael addition reactions of α-cyanoketene-S,S-acetals 1 with enones 2 have been developed. The polyfunctionalized 2-[1,3]dithiolan-2-ylidene-3-substituted-5-oxo-5-substituted-pentanenitriles 3 were obtained in good to high yields and the corresponding mechanism was also described.     

A New Diarylheptanoid from the Barks of Betula platyphylla

Chemistry of Natural Compounds - A new diarylheptanoid, 3,4-dihydroxy-1,7-bis(4′ ,4′′-dihydroxyphenyl)-heptane (1), was isolated from the ethyl acetate extract of Betula...     

Rydberg states and ionization potentials of GeX,SnX, and PbX (X = F,Cl, Br,I)

Thirty-nine unattributed electronic states of group IV monohalides have been interpreted in terms of Rydberg configurations. Ionization potential and quantum defects have been derived.     

One-pot synthesis of a novel chiral Zr-based metal-organic framework for capillary electrochromatographic enantioseparation

A novel chiral stationary phase (CSP) of Zr-based metal-organic framework, l -Cys-PCN-224, was prepared by one-pot method and applied for the enantioseparation by capillary electrochromatography. The CSP was characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier-transform infrared spectra, nitrogen adsorption/desorption, circular dichroism spectrum, zeta-potential, and so on. The results revealed that the CSP had good crystallinity, high specific surface area (2580 m²/g), and good thermal stability. Meanwhile, the cross-section of l -Cys-PCN-224-bonded open-tubular (OT) column was observed by a scanning electron microscope, which proved the successful bonding of l -Cys-PCN-224 particles to the inner wall. Relative standard deviations of the column efficiencies were 3.87%–9.14%, and not obviously changed after 200 runs, which indicated that l -Cys-PCN-224-bonded OT column had the better stability and reproducibility. Excellent chiral separation performance was verified with nine kinds of natural amino acids including acidic, neutral, and basic as the analytes. All amino acids studied achieved good separation with the resolution of 1.38–13.9 and selector factor of 1.11–3.71. These results demonstrated that the CSP had an excellent potential in the chiral separation field.     

电动力学课程思政建设的思考与实践

开展专业课程的思政建设是当今教育领域的一个重要的研究问题,本文结合物理学专业的电动力学课程进行课程思政建设的研究和实践,有机结合课程内容和特点,挖掘课程思政元素和切入点,通过教学实践初步取得教学效果,对理科专业课程思政建设起到积极的借鉴和推动作用,真正做到课程育人,发挥课程应有的作用,并提出总结和展望.     

EV自回归模型的一个相合估计

考虑带有测量误差的自回归模型,在不对替代变量和真实变量之间的关系做任何模型假设的情况下,借助核实数据,给出未知参数的一个基于核实与替代两方面信息的最小二乘估计量,并证得该估计量是相合估计.     

纳米复合材料TiO2-ZrO2光催化降解可溶性染料的研究

采用溶胶-凝胶方法将光催化剂TiO2和ZrO2复合,再经700℃灼烧5h后获得了纳米复合光催化材料TiO2-ZrO2.该材料经XRD检测具有光催化活性良好的晶型结构.TEM测定结果显示产物的平均粒径约为20nm.通过对可溶性染料刚果红等的光催化降解实验证明,该复合材料具有较高的光催化活性.     

益智红外指纹图谱的研究

益智产区的鉴别对于药材市场的质量控制以及提高药材的质量显得极为重要。益智为我国四大南药之一, 主要药效成分是诺卡酮和益智酮。红外指纹图谱用于中药质量控制研究有着良好的发展前景,借助红外光谱的指纹特性,以八种益智精油红外指纹图谱的共有峰率和变异峰率为指标,计算了样品相对于该标准品的共有峰率和变异峰率, 并按照共有峰率、变异峰率的大小建立了不同的序列。结果表明：广东、广西和海南的益智油红外图谱比较吻合,但也存在一定的差异。益智油的红外图谱特征峰为1 710和1 666 cm-1 ,广东和海南的益智油的红外指纹图谱(400～4 000 cm-1)共有峰率为62%,广西和海南的共有峰率为52%,海南的益智油共有峰率为66%～84%。从多维共有峰率和变异峰率双指标序列分析法可以对不同产地具有准确、精细且非常直观的鉴别能力, 该方法可以准确地区别不同产地的益智。     

红外光谱法测定固相微萃取新型吸附质中单体的摩尔比

以丙烯酸丁酯和苯乙烯为单体 ,过氧化苯甲酰为引发剂 (用量为wt 0 3% ) ,醋酸丁酯和甲苯作混合溶剂 ,溶剂用量与单体混合物的体积相同 ,采用溶液聚合的方法合成了一种新型固相微萃取吸附质 (苯乙烯 丙烯酸丁酯共聚物 )。以朗伯 比耳定律为依据 ,通过一系列的推导过程 ,得出了共聚物中两种官能团的吸收值比与共聚物中两种单体摩尔比的线性关系式A1 /A2 =kn1 /n2 。采用红外光谱法测定聚合物中两种官能团的吸收值比 ,再通过外标曲线法确定了共聚物中两种官能团的吸收值比 (y)与共聚物中两种单体的摩尔比 (x)的线性回归方程 y =0 136 2 0 0 84 1x。方法的精密度RSD(% ) =2 4 6 4 ,方法的回收率为 92 89%～10 3 94 %。红外光谱法测定作为固相微萃取新型吸附质的苯乙烯与丙烯酸丁酯共聚物中单体的摩尔比是一种快速准确的分析方法