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41.
Ying Lv Bofeng Zhang Guobing Zou Xiaodong Yue Zhikang Xu Haiyan Li 《Entropy (Basel, Switzerland)》2022,24(7)
Domain adaptation aims to learn a classifier for a target domain task by using related labeled data from the source domain. Because source domain data and target domain task may be mismatched, there is an uncertainty of source domain data with respect to the target domain task. Ignoring the uncertainty may lead to models with unreliable and suboptimal classification results for the target domain task. However, most previous works focus on reducing the gap in data distribution between the source and target domains. They do not consider the uncertainty of source domain data about the target domain task and cannot apply the uncertainty to learn an adaptive classifier. Aimed at this problem, we revisit the domain adaptation from source domain data uncertainty based on evidence theory and thereby devise an adaptive classifier with the uncertainty measure. Based on evidence theory, we first design an evidence net to estimate the uncertainty of source domain data about the target domain task. Second, we design a general loss function with the uncertainty measure for the adaptive classifier and extend the loss function to support vector machine. Finally, numerical experiments on simulation datasets and real-world applications are given to comprehensively demonstrate the effectiveness of the adaptive classifier with the uncertainty measure. 相似文献
42.
Shixiong Chen Xiaotian Zhao Ming Jin Wanqiu Huang Guodong Ye Haiyan Pan Decheng Wan 《Journal of polymer science. Part A, Polymer chemistry》2021,59(17):1899-1911
Four 1,5-diphenyl-3-aromatic heterocyclyl-2-pyrazoline-based sulfonium salt photoacid generators (PAGs) with different aromatic heterocycles substituted on C3 atom and dimethyl sulfonium group on C5 atom were synthesized. These PAGs were highly photosensitive in the 365–425 nm light-emitting diode region, and the intramolecular charge transfer from the pyrazoline ring to sulfonium salts induced efficient photolysis and high ΦH+. The heterocycles as well as their substituted positions significantly influenced the energy of the S2 orbital, which was determined by the electrochemical and absorption properties of the PAGs. The raising of the S2 orbital energy enlarged the energy gap of S0–S2 and S1–S2, resulting in blue shift of the absorption spectra and increase in the quantum yield of photoacid generation (ΦH+), respectively. When the energy of excited electrons was higher than that of the S2 orbital, the transition from S0 to S2 (π–π*) occurred before the C-S cleavage on S1 and the PAGs showed high ΦH+ values (0.52–0.72). The transition from S0 to S1 (π–σ*) occurred when the energy of electrons is lower than that of the S2 orbital, and the PAGs showed low ΦH+ value. The photopolymerization kinetics demonstrated that these PAGs were highly efficient cationic photoinitiators. 相似文献
43.
JPC – Journal of Planar Chromatography – Modern TLC - High-performance thin-layer chromatography (HPTLC) was used for the qualitative and quantitative analysis of... 相似文献
44.
应用微穿孔板吸声结构的飞机座舱内部噪声控制实验研究 总被引:3,自引:1,他引:2
针对某些特殊情况下飞机座舱内部噪声过大的实际情况,对其进行了噪声无源控制实验研究。以某飞机座舱模型为研究对象,利用微穿孔板吸声结构成功实现了一套飞机座舱模型内部噪声无源控制系统。同时利用Cada-X结构动力学分析系统建立了一套振动噪声控制性能测试系统,可广泛应用于各种振动噪声有源、无源控制系统的控制性能测试。同时对所设计的微穿孔板吸声结构吸声系数进行了理论计算和实验测量,对比结果表明其一致性良好。最后利用该测试系统对飞机座舱模型噪声无源控制系统进行了控制性能测试,控制效果明显。从而说明了此方法对飞机座舱内部噪声抑制的有效性和可行性。 相似文献
45.
多硝基多氨基三唑类衍生物作为含能材料,具有高氮、致密、钝感等优点。本文通过3-氨基-1,2,4-三唑和三硝基三氯苯的缩合,再经过三唑碳原子上的硝化反应和芳环上的氨化反应,合成并鉴定了标题化合物。 相似文献
46.
载体对负载型TiO2催化剂光催化性能的影响 总被引:22,自引:0,他引:22
以活性碳(AC)和镁铝尖晶石(MA)为载体,采用真空吸附水解法制备了负载型光催化剂TiO2/AC和TiO2/MA,并采用TiO2溶胶负载法制备了活性碳负载催化剂TiO2(C)/AC.以氯仿为探针分子研究了其在催化剂上的吸附及光催化降解反应性能.结果表明,催化剂的制备方法、TiO2负载量与载体的吸附性能对光催化活性有明显的影响.通过优化制备条件,TiO2/AC催化剂的催化活性可提高到纳米TiO2的2.5倍.氯仿在AC上的饱和吸附量较高,但吸附强度较弱;在纳米TiO2上的吸附情况则正好相反.氯仿在AC和TiO2上吸附性质的差异有利于吸附在TiO2/AC上的氯仿分子从活性碳载体向TiO2光催化活性中心迁移.镁铝尖晶石载体对光催化反应没有明显的促进作用,与其基本上不吸附氯仿分子有关.与TiO2胶体负载法相比,真空吸附水解法是一种较好的负载型TiO2光催化剂制备方法. 相似文献
47.
Taotao Hao Yongsheng Yang Wenting Liang Chunying Fan Xin Wang Wanhua Wu Xiaochuan Chen Haiyan Fu Hua Chen Cheng Yang 《Chemical science》2021,12(7):2614
Stilbene derivatives have long been known to undergo “acid-catalyzed” Z → E isomerization, where a strong mineral acid at high concentration is practically necessary. Such severe reaction conditions often cause undesired by-reactions and limit their potential application. Herein, we present a trace mild acid-catalyzed Z → E isomerization found with stilbene derivatives fused with a norbornene moiety. By-reactions, such as the migration of the C C double bond and electrophilic addition reactions, were completely inhibited because of the ring strain caused by the fused norbornene component. Direct photolysis of the E isomers at selected wavelengths led to the E → Z photoisomerization of these stilbene derivatives and thus constituted a unique class of molecular switches orthogonally controllable by light and acid. The catalytic amount of acid could be readily removed, and the Z → E isomerization could be controlled by turning on/off the irradiation of a photoacid, which allowed repeated isomerization in a non-invasive manner. Moreover, the Z isomer produced by photoisomerization could spontaneously self-recover to the E isomer in the presence of a catalytic amount of acid. The kinetics of Z → E isomerization were adjustable by manipulating catalytic factors and, therefore, unprecedented molecular photoswitches with adjustable self-recovery were realized.Quantitative Z → E isomerization was catalyzed by trace mild acids to offer molecular switches orthogonally controllable by acid and light. 相似文献
48.
Chen H Aleksandrov A Chen Y Zha S Liu M Orlando TM 《The journal of physical chemistry. B》2005,109(22):11257-11262
Polycrystalline gadolinia-doped ceria (GDC) surfaces were studied using low-energy (5-400 eV) electron stimulated desorption (ESD). H(+), O(+), and H(3)O(+) were the primary cationic desorption products with H(+) as the dominant channel. H(+), H(3)O(+), and O(+) have a 22 eV threshold followed by a yield change around 40 eV. H(+) also has an additional yield change approximately 75 eV and O(+) has an additional change approximately 150 eV. The O(+) ESD yield change approximately 150 eV may indicate bond breaking of Gd-O and the involvement of oxygen vacancies. The H(+) and H(3)O(+) threshold data collectively indicate the presence of hydroxyl groups and chemisorbed water molecules on the GDC surfaces. ESD temperature dependence measurements show that the interaction of water with GDC surface defect sites, mainly oxygen vacancies, influences the desorption of H(+), O(+), and H(3)O(+). The temperature dependence of the O(+) ESD at 400 eV incident electron energy yields a 0.21 eV activation energy. This is close to the energy needed for oxygen vacancy production next to a pair of Ce(3+) on a CeO(2) surface. These results may indicate a correlation between the O(+) ESD yield and oxygen vacancy density on GDC surfaces and a potential correlation of O(+) ESD and GDC ionic conductivity. 相似文献
49.
A One‐Step Route to CO2‐Based Block Copolymers by Simultaneous ROCOP of CO2/Epoxides and RAFT Polymerization of Vinyl Monomers 下载免费PDF全文
Dr. Yong Wang Yajun Zhao Prof. Dr. Yunsheng Ye Prof. Dr. Haiyan Peng Prof. Dr. Xingping Zhou Prof. Dr. Xiaolin Xie Prof. Dr. Xianhong Wang Prof. Dr. Fosong Wang 《Angewandte Chemie (International ed. in English)》2018,57(14):3593-3597
The one‐step synthesis of well‐defined CO2‐based diblock copolymers was achieved by simultaneous ring‐opening copolymerization (ROCOP) of CO2/epoxides and RAFT polymerization of vinyl monomers using a trithiocarbonate compound bearing a carboxylic group (TTC‐COOH) as the bifunctional chain transfer agent (CTA). The double chain‐transfer effect allows for independent and precise control over the molecular weight of the two blocks and ensures narrow polydispersities of the resultant block copolymers (1.09–1.14). Notably, an unusual axial group exchange reaction between the aluminum porphyrin catalyst and TTC‐COOH impedes the formation of homopolycarbonates. By taking advantage of the RAFT technique, it is able to meet the stringent demand for functionality control to well expand the application scopes of CO2‐based polycarbonates. 相似文献
50.
Electrochemical Reduction of Carbon Dioxide to Methanol on Hierarchical Pd/SnO2 Nanosheets with Abundant Pd–O–Sn Interfaces 下载免费PDF全文
Wuyong Zhang Qing Qin Dr. Lei Dai Ruixuan Qin Dr. Xiaojing Zhao Xumao Chen Daohui Ou Dr. Jie Chen Dr. Tracy T Chuong Prof. Binghui Wu Prof. Nanfeng Zheng 《Angewandte Chemie (International ed. in English)》2018,57(30):9475-9479
Electrochemical conversion of CO2 into fuels using electricity generated from renewable sources helps to create an artificial carbon cycle. However, the low efficiency and poor stability hinder the practical use of most conventional electrocatalysts. In this work, a 2D hierarchical Pd/SnO2 structure, ultrathin Pd nanosheets partially capped by SnO2 nanoparticles, is designed to enable multi‐electron transfer for selective electroreduction of CO2 into CH3OH. Such a structure design not only enhances the adsorption of CO2 on SnO2, but also weakens the binding strength of CO on Pd due to the as‐built Pd–O–Sn interfaces, which is demonstrated to be critical to improve the electrocatalytic selectivity and stability of Pd catalysts. This work provides a new strategy to improve electrochemical performance of metal‐based catalysts by creating metal oxide interfaces for selective electroreduction of CO2. 相似文献