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81.
损伤是结构振动测试和运营维护中不可避免的问题,损伤效应会导致结构振动特性发生改变.本文以受损悬索为例,探究该非线性系统同时发生主共振和2:1内共振时,损伤效应对其面内耦合共振响应影响.首先基于哈密顿变分原理,引入与损伤程度、范围和位置相关的三个无量纲参数,建立受损悬索面内动力学模型,并推导其无穷维非线性运动微分方程.以2:1耦合共振为例,采用Galerkin法和多尺度法得到系统直角坐标形式的调谐方程.数值算例表明:损伤会导致悬索固有频率降低,使得频率间公倍关系发生改变,影响系统耦合共振响应;损伤会引发系统振动特性发生明显定量和定性改变,尤其是共振响应幅值及弹簧特性;损伤对直接激励模态响应幅值的影响比对内共振激发对响应幅值的影响要明显;损伤会导致霍普夫、鞍节点、叉形和倍周期分岔的位置发生偏移,从而影响分岔点附近系统的动力学行为;系统动态解和周期运动与损伤密切相关,损伤会导致系统展现出完全不同类型的吸引子. 相似文献
82.
Methodology and Computing in Applied Probability - In chemical graph theory, caterpillar trees have been an appealing model to represent the molecular structures of benzenoid hydrocarbon.... 相似文献
83.
Lili Jiang Xiangjun Peng Panpan Huang Zhengwang Chen Liangxian Liu 《Tetrahedron》2017,73(11):1389-1396
A method for the combinative oxidative homo dimerization and cyanation of free indole derivatives catalysed by TEMPO along with silver carbonate was demonstrated for the first time This new methodology is both atom and step efficient and is applicable to a broad scope of substrates, allowing the synthesis of a range of synthetically valuable 2-(1H-indol-3-yl)-3-oxoindoline- 2-carbonitriles in moderate to excellent yields. Furthermore, selected compounds 6b and 6g exhibit moderate to good anti-schistosomicidal activities. 相似文献
84.
85.
Determination of Alizarin Red S using a novel B-Z oscillation system catalyzed by a tetraazamacrocyclic complex 总被引:1,自引:0,他引:1
Gang Hu Lulu Chen Jinfeng Zhang Panpan Chen Wei Wang Jimei Song Lingguang Qiu Juan Song Lin Hu 《Central European Journal of Chemistry》2009,7(3):291-297
A new and convenient method for the determination of Alizarin Red S by the perturbations caused by different amounts of Alizarin
Red S on a novel B-Z oscillating system is proposed. This new type Belousov-Zhabotinskii involves a macrocyclic copper(II)
complex [CuL](ClO4)2 as catalyst and malic acid as the substrate. The ligand L in the complex is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene.
It is found that the relationship between the change in the oscillation amplitude and the logarithm of the Alizarin Red S
concentration in the range of 1.5 × 10−7 to 1 × 10−3 M fits a polynomial model: ΔA = 659 + 184.2 log [Alizarin Red S]+ 12.9 log2 [Alizarin Red S]. The RSD obtained with ten samples is 4.4%. The probable mechanism involving the perturbation of Alizarin
Red S on the oscillating chemical system is also discussed.
相似文献
86.
Feng Zhu Panpan Zhang Dr. Xuejun Wu Prof. Limin Fu Prof. Jianping Zhang Prof. Dongsheng Xu 《Chemphyschem》2012,13(16):3731-3737
Zn‐doped anatase TiO2 nanoparticles are synthesized by a one‐step hydrothermal method. Detailed electrochemical measurements are undertaken to investigate the origin of the effect of Zn doping on the performance of dye‐sensitized solar cells (DSSCs). It is found that incorporation of Zn2+ into an anatase lattice elevates the edge of the conduction band (CB) of the photoanodes and the Fermi level is shifted toward the CB edge, which contributes to the improvement in open‐circuit voltage (VOC). Charge‐density plots across the cell voltage further confirm the increase in the CB edge in DSSCs directly. Photocurrent and transient photovoltage measurements are employed to study transport and recombination dynamics. The electron recombination is accelerated at higher voltages close to the CB edge, thus leading to a negative effect on the VOC. 相似文献
87.
A novel anionic polymerizable surfactant sodium (5‐acryloyl‐2‐(dodecyloxy)phenyl) methane sulfonate has been synthesized from phenol, acrylic acid and bromododecane by esterification, Frise rearrangement, sulfomethylation reaction and Williamson etherification. The parameters of the micellar behaviors are as follows: The CMC was 150 ppm at 40 °C; The surface absorption amounts Γm was 3.208 × 10?6 mol m?2; The molecular areas Am was 0.550 × 10?18m2 at the interface of air‐water respectively; The aggregation number (Nagg) at C = CMC of this surfactant was 12. 相似文献
88.
Yueyu Tong Haipeng Guo Daolan Liu Xiao Yan Panpan Su Ji Liang Si Zhou Jian Liu Gao Qing Lu Shi Xue Dou 《Angewandte Chemie (International ed. in English)》2020,59(19):7356-7361
The electrochemical nitrogen reduction reaction (NRR) is a promising energy‐efficient and low‐emission alternative to the traditional Haber–Bosch process. Usually, the competing hydrogen evolution reaction (HER) and the reaction barrier of ambient electrochemical NRR are significant challenges, making a simultaneous high NH3 formation rate and high Faradic efficiency (FE) difficult. To give effective NRR electrocatalysis and suppressed HER, the surface atomic structure of W18O49, which has exposed active W sites and weak binding for H2, is doped with Fe. A high NH3 formation rate of 24.7 μg h?1 mgcat?1 and a high FE of 20.0 % are achieved at an overpotential of only ?0.15 V versus the reversible hydrogen electrode. Ab initio calculations reveal an intercalation‐type doping of Fe atoms in the tunnels of the W18O49 crystal structure, which increases the oxygen vacancies and exposes more W active sites, optimizes the nitrogen adsorption energy, and facilitates the electrocatalytic NRR. 相似文献
89.
Dr. Mo Wang Lu Zhang Dr. Xiaohong Huo Dr. Zhenfeng Zhang Dr. Qianjia Yuan Panpan Li Dr. Jianzhong Chen Yashi Zou Dr. Zhengxing Wu Prof. Dr. Wanbin Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21000-21005
The catalytic asymmetric synthesis of the anti-COVID-19 drug Remdesivir has been realized by the coupling of the P-racemic phosphoryl chloride with protected nucleoside GS441524. The chiral bicyclic imidazole catalyst used is crucial for the dynamic kinetic asymmetric transformation (DyKAT) to proceed smoothly with high reactivity and excellent stereoselectivity (96 % conv., 22:1 SP:RP). Mechanistic studies showed that this DyKAT is a first-order visual kinetic reaction dependent on the catalyst concentration. The unique chiral bicyclic imidazole skeleton and carbamate substituent of the catalyst are both required for the racemization process, involving the phosphoryl chloride, and subsequent stereodiscriminating step. A 10 gram scale reaction was also conducted with comparably excellent results, showing its potential for industrial application. 相似文献
90.
Jingjing Shi Xiaosi Zhu Panpan Xu Mengmeng Zhu Yitong Guo Yaowu He Zhao Hu Imran Murtaza Hongtao Yu Lijia Yan Osamu Goto Hong Meng 《Macromolecular rapid communications》2016,37(16):1344-1351
Organic electrochromic materials change color rapidly under applied potential. A butterfly‐shaped compound, 5,5′,‐5″,‐5′″‐(thieno[3,2‐b]thiophene‐2,3,5,6‐tetrayl) tetrakis‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxine) (t‐EDOT‐TT) is synthesized for the first time and polymerized at different potentials via electropolymerization technique. By applying different polymerization potentials, the optical and electrochromic properties of this newly synthesized polymer can be tuned. Owing to the dependence of functional group position in the polymer structure on the redox potential, this polymer can be utilized in very interesting organic optoelectronic applications.