检索结果-南通市图书馆

Chinese Journal of Polymer Science 2018年第5期36卷 584-591页

作者： yi-Gang Luan Xiao-A Zhang sheng-Ling Jiang Jian-Huan chen Ya-Fei Lyu Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education College of Materials Science and Engineering Beijing University of Chemical Technology

A self-healing supramolecular polymer composite（HSP-GO） was designed and prepared via incorporation of modified graphene oxide to hyperbranched polymer by hydrogen-bonding interactions. The polymer matrix based on amino-terminated hyperbranched polymer（HSP-NH_2） was synthesized by carboxylation, Curtius rearrangement, and amination of hydroxyl-terminated hyperbranched polyester（HP-OH）, while the modified graphene oxide was prepared by transformation of hydroxyl to isocyanate and further to carbamate ester. Spectroscopic methods were utilized to characterize the obtained polymer composites. Stress-strain test was selected to carefully study the self-healing property of HSP-GO. It is found that a small amount of modified graphene oxide（up to 2 wt%） improves the glass transition temperature（T_g）, tensile strength, Young＇s modulus, and self-healing efficiency of the polymer composites. After healed at room temperature for 10 min, the addition of modified graphene oxide improves the self-healing efficiency to 37% of its original tensile strength. The experiment result shows that the self-healing efficiency is related to the density of hydrogen bonding site and the molecular movement.

关键词： Self-healing Supramolecular polymer Graphene oxide Hydrogen bonding

Solid State NMR and Fluorescence Studies of Conjugated Polymer Nanocomposties

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2005年第11期16卷 1519-1522页

作者： Chao Jun JING Liu sheng chen yi SHI Xi Gao JIN State Key Laboratory of Polymer Physics and Chemistry Institute of Chemistry Chinese Academy of Sciences Beijing 100080 Graduate School of the Chinese Academy of Sciences Beijing 100080

^13C spin-lattice relaxation times （T1） of a conjugated polymer MEH-PPV in polymer/ layered silicate nanocomposites together with the steady state fluorescence emission and transient fluorescence decay measurements have been investigated. The T1 values of the conjugated carbons decrease dramatically according to the reduction of polymer concentration in the nano composites, while the fluorescence life times （τ） show a linear prolonging tendency. The results are explained from the point of view of molecular dynamics.

关键词： Conjugated polymer nanocomposites fluorescence solid state ^13C NMR

Unsupervised Recognition of Informative Features via Tensor Network Machine Learning and Quantum Entanglement Variations

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2022年第10期39卷 12-16页

作者： sheng-chen Bai yi-cheng Tang Shi-Ju Ran Department of Physics Capital Normal UniversityBeijing 100048China

Given an image of a white shoe drawn on a blackboard,how are the white pixels deemed(say by human minds)to be informative for recognizing the shoe without any labeling information on the pixels?Here we investigate such a“white shoe”recognition problem from the perspective of tensor network(TN)machine learning and quantum *** a generative TN that captures the probability distribution of the features as quantum amplitudes,we propose an unsupervised recognition scheme of informative features with variations of entanglement entropy(EE)caused by designed *** this way,a given sample,where the values of its features are statistically meaningless,is mapped to the variations of EE that statistically characterize the gain of *** show that the EE variations identify the features that are critical to recognize this specific sample,and the EE itself reveals the information distribution of the probabilities represented by the TN *** signs of the variations further reveal the entanglement structures among the *** test the validity of our scheme on a toy dataset of strip images,the MNIST dataset of hand-drawn digits,the fashion-MNIST dataset of the pictures of fashion articles,and the images of nerve *** scheme opens the avenue to the quantum-inspired and interpreted unsupervised learning,which can be applied to,e.g.,image segmentation and object detection.

关键词： quantum scheme tensor

Real-Time Monitoring and Quantitative Evaluation of Cavitation Bubbles Induced by High Intensity Focused Ultrasound Using B-Mode Imaging

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2014年第3期31卷 91-95页

作者： YU Jie chen Chu-yi chen Gong GUO Xia-sheng MA Yong TU Juan ZHANG Dong Key Laboratory of Modern Acoustics School of Physics Nanjing University Nanjing 210093 Traditional Chinese Medicine Hospital of Jiangsu Province Nanjing 210023 State Key Laboratory of Acoustics Chinese Academy of Sciences Beijing 100190

A software-based method is proposed to eliminate the flooding interference strips in B-mode images, and to evaluate the cavitation bubbles generated during high intensity focused ultrasound （HIFU） exposures. In vitro tissue phantoms are exposed to 1.12 MHz HIFU pulses with a fixed 100 Hz pulse repetition frequency. HIFU-induced cavitation bubbles are detected as hyperechoic regions in B-mode images. The temporal evolution of cavitation bubbles, generated by HIFU pulses with varying driving amplitude and pulse length, is analyzed by measuring the time-varying area of the hyperechoic region. The results show that： first, it is feasible to monitor HIFU-induced cavitation bubble activity in real-time using B-mode imaging; second, more cavitation bubbles can be generated with higher acoustic energy delivered; third, the hyperechoic region is observed to shrink gradually after ceasing the HIFU pulses, which indicates the dissolution of cavitation bubbles. This work will be helpful for developing an effective tool to realize real-time monitoring and quantitative evaluation of HIFU-induced cavitation bubble activity using a current commercialized B-mode machine.

关键词： Cavitation

Enhancing recommender systems by incorporating social information

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science C(Computers and Electronics) 2013年第9期14卷 711-721页

作者： Li-wei HUANG Gui-sheng chen Yu-chao LIU De-yi LI Institute of Command Information System PLA University of Science and Technology Institute of Electronic System Engineering

Although recommendation techniques have achieved distinct developments over the decades,the data sparseness problem of the involved user-item matrix still seriously influences the recommendation *** of the existing techniques for recommender systems cannot easily deal with users who have very few *** to combine the increasing amount of different types of social information such as user generated content and social relationships to enhance the prediction precision of the recommender systems remains a huge *** this paper,based on a factor graph model,we formalize the problem in a semi-supervised probabilistic model,which can incorporate different user information,user relationships,and user-item ratings for learning to predict the unknown *** evaluate the method in two different genres of datasets,Douban and *** indicate that our method outperforms several state-of-the-art recommendation ***,a distributed learning algorithm is developed to scale up the approach to real large datasets.

关键词： Recommender system Social information Factor graph model

Synthesis of Exfoliated MEH-PPV /Clay Nanocomposites

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2005年第8期16卷 1117-1120页

The synthesis of poly（2-methoxy-5-（2＇-ethyl-hexyloxy）-l,4-phenylenevinylene）（MEH-PPV） in the presence of organophilic montmorillonite （OMMT） was reported and the exfoliated MEH-PPV/OMMT nanocomposites was ob... 详细信息

关键词： MEH-PPV nanocomposite in-situ polymerization.

A novel sort of porous ceramic foam ball with modified surface for arsenic removal from aqueous solution

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2017年第6期24卷 661-668页

作者： Pei-sheng Liu Guang Cui yi-jiao Guo Jing-he chen Zi-xuan Yang College of Nuclear Science and Technology Beijing Normal University Beijing 100875 China

A sort of lightwerght porous ceramic foam ball that can float on the water was recently made from the nat- ural zeolite. The diameters of porous hall and its macroscopic pores are around 5 and 1 mm, respectively. Such ball surface could be modified to activate in different ways, i. e. loading the active alumina or desili- cating the ball. Both of modified products have been investigated to adsorb the toxic ion of arsenic （As） in water effectively. This kind of porous ceramic hall was prepared by powder sintering, using natural clinop- tilolite powder as the primary raw material. An active-alumina loaded porous ceramic product was genera- ted by sol-gel method with pseudoboehmite （A1OOH） as the main composition. The active AI atom on the porous ball surface could also be achieved by desilicating the ceramic ball in the NaOH solution. Such a desilicated product exhibited a good activity to adsorb the arsenic ion although carrying no ac- tive alumina. With this effective porous structure, the present products can be expected to become practically advantageous.

关键词： Porous materialCeramic foamPorous ceramic ballSurface modificationArsenic removal

Channel Temperature Measurement of AlGaN/GaN HEMTs by Forward Schottky Characteristics

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2011年第1期28卷 171-174页

作者： ZHANG Guang-chen FENG Shi-Wei HU Pei-Feng ZHAO Yan GUO Chun-sheng XU Yang chen Tang-sheng JIANG yi-Jian School of Electronic Information & Control Engineering Beijing University of Technology Beijing 100124 Institute of Laser Engineering Beijing University of Technology Beijing 100124 Nanjing Electronic Devices Institute Nanjing 210016

Channel temperature measurements of multi-finger AlGaN/OaN HEMTs by forward Schottky characteristics are presented. The temperature dependence of the forward gate-source Schottky junction voltage is investigated and it is used as the temperature sensitive parameter （TSP） by pulsed switching technique. The channel-to-mounting thermal resistance of the tested AlGaN/GaN HEMT sample is 19.6°C/W. Compared with both the measured results by micro-Raman method and simulated results of a three-di^nensional heat conduction model, the physical meaning of the channel temperature for AIGaN/GaN HEMT tested by pulsed switching electrical TSP method is investigated quantitatively for the first time.

关键词： Temperature Measurement Testing Testes Methods Grain legumes

Encapsulation and Fluorescence of the Functional Supramolecular Material Between MCM-41 and Rh6G

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2000年第3期16卷 263-265页

作者： ZHANG Mai-sheng ZU yi-gan YANG Yan-sheng chen Jie-sheng FENG Shou-hua XU Ru-ren School of Chemical and Engineering Zhongshan UniversityGuangzhou 510275P.R.China Department of Chemistry Jilin UniversityChangchun 130023P.R.China

Molecular sieves encapsulated organic dyes and metal chelates were reviewed and luminescent behavior of some organic compounds in molecular sieves was studied. Rh6G is one kind of organic dye which is widely used in many fields such as optics, spectroscopy, and laser techniques. It has a high stability and an efficiency quantum yield as an excellent fluorescent compound. The encapsulation and the fluorescence of the functional supramolecular material of MCM-41, which was synthesized by means of microwave radiation method (MRM), encapsulated Rh6G was reported.

关键词： MCM 41 Microwave radiation Rhodamine 6G Supramolecular material Fluorescence

LFV decays of Z boson in Minimal R-symmetric Supersymmetric Standard Model

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2019年第4期43卷 45-53页

作者： Ke-sheng Sun Jian-Bin chen Xiu-yi Yang sheng-Kai Cui Department of Physics Baoding University College of Physics and Optoelectronic Engineering Taiyuan University of Technology School of Science University of Science and Technology Liaoning Department of Physics Hebei University

A future Z-factory will offer the possibility of studying rare Z decays Z → l_1l_2, such as those leading to lepton flavor violation(LFV) final states. In this work, by considering the constraints from radiative two-body decays l_2→ l_1γ, we investigate the LFV decays Z → l_1l_2 in the framework of the Minimal R-symmetric Supersymmetric Standard Model with two benchmark points from the existing literature. The flavor-violating off-diagonal entries Б^(12), Б^(13) and Б^(23) are constrained by the current experimental bounds of l_2→ l_1γ. Considering recent experimental constraints, we also investigate Br(Z → l_1l_2) as a function of M_D^W. The numerical results show that the theoretical predictions of Br( Z → l_1l_2) in the MRSSM are several orders of magnitude below the current experimental bounds. The LFV decays Z → eτ and Z →μт may be promising observation targets in future experiments.

关键词： R-symmetry MRSSM lepton flavor violation