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Investigation on UV-curing Reprocessable Thermosets Bearing Hindered Urea Bonds and Their Composites with Modified Zinc Oxide Nanoparticles

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Chinese Journal of Polymer Science 2024年第6期42卷 751-765页

作者： Jun-Hao Zhou Li-ming tang Key Laboratory of Advanced Materials of Ministry of Education of China Department of Chemical EngineeringTsinghua UniversityBeijing100084China

In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot *** prepolymers were characterized fully by various ***,their thermosets were fabricated via UV curing in presence of a photo initiator,and their mechanical property and thermal behavior were investigated and *** from the none HUB containing thermoset,the HUB containing thermosets(defined as PUT)could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical ***,zinc oxide(ZnO)nanoparticles were modified with 3-(trimethoxysilyl)propyl methacrylate and the modified ZnO(defined as ZnO-TPM)was dispersed and polymerized into PUT matrix to prepare their *** influence of ZnO-TPM on the mechanical performance of the composites was evaluated,which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt%and then *** composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT *** addition,the composite materials exhibited strong UV absorption capacity,implying their potential application in the circumstance where UV-shielding was required.

关键词： Polyurethane-urea methacrylate Hindered urea bond ZnO nanoparticles Reprocessing UV curing

Fast method for spreading sequence estimation of DSSS signal based on maximum likelihood function

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Journal of Systems Engineering and Electronics 2010年第6期21卷 948-953页

作者： Yanhua Peng Bin tang ming Lv College of Electronic Engineering University of Electronic Science and Technology of China Chengdu 610054 E R. China

To estimate the spreading sequence of the direct sequence spread spectrum (DSSS) signal, a fast algorithm based on maximum likelihood function is proposed, and the theoretical derivation of the algorithm is provided. By simplifying the objective function of maximum likelihood estimation, the algorithm can realize sequence synchronization and sequence estimation via adaptive iteration and sliding window. Since it avoids the correlation matrix computation, the algorithm significantly reduces the storage requirement and the computation complexity. Simulations show that it is a fast convergent algorithm, and can perform well in low signal to noise ratio (SNR).

关键词： direct sequence spread spectrum (DSSS) signal spreading sequence maximum likelihood estimation (MLE).

High Mg# of the continental crust explained by calc-alkaline differentiation

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National Science Review 2023年第3期10卷 92-99页

作者： ming tang Xuanyu Liu Kang Chen Key Laboratory of Orogenic Belt and Crustal Evolution Ministry of Education School of Earth and Space Sciences Peking University State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences

We used compiled geochemical data to investigate the mechanisms that control Mg#(molar ratio of Mg/(Mg+FeT)) in andesitic arc *** find that andesites from mature continental arcs with crustal thickness of>45 km have systematically higher Mg# than those from oceanic arcs with crustal thickness of<30 *** elevated Mg# in continental arc lavas results from strong Fe depletion during high-pressure differentiation favored in thick *** proposal is reinforced by our compiled melting/crystallization experiment *** show that the Mg# characteristics of continental arc lavas match that of the continental *** findings suggest that the formation of many high-Mg#andesites and the continental crust may not require slab-melt/peridotite ***,the high Mg# of the continental crust can be explained by intracrustal calc-alkaline differentiation processes in magmatic orogens.

关键词： high-Mg# andesite calc-alkaline differentiation Fe depletion slab melting continental crust

Perfect spin filtering controlled by an electric field in a bilayer graphene junction:Effect of layer-dependent exchange energy

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Chinese Physics B 2016年第7期25卷 488-496页

作者： Kitakorn Jatiyanon I-ming tang Bumned Soodchomshom Department of Physics Faculty of Science Kasetsart University Department of Materials Science Faculty of Science Kasetsart University

Magneto transport of carriers with a spin-dependent gap in a ferromagnetic-gated bilayer of graphene is *** focus on the effect of an energy gap induced by the mismatch of the exchange fields in the top and bottom layers of an AB-stacked graphene bilayer. The interplay of the electric and exchange fields causes the electron to acquire a spindependent energy gap. We find that, only in the case of the anti-parallel configuration, the effect of a magnetic-induced gap will give rise to perfect spin filtering controlled by the electric field. The resolution of the spin filter may be enhanced by varying the bias voltage. Perfect switching of the spin polarization from ＋100% to -100% by reversing the direction of electric field is predicted. Giant magnetoresistance is predicted to be easily realized when the applied electric field is smaller than the magnetic energy gap. It should be pointed out that the perfect spin filter is due to the layer-dependent exchange energy. This work points to the potential application of bilayer graphene in spintronics.

关键词： bilayer graphene spin filter magnetoresistance spintronics

INFLUENCE OF MOLECULAR STRUCTURES OF SECONDARY AMINE TERMINATED POLY(ESTER-AMINE)S ON THE CURING PERFORMANCE WITH EPOXY RESIN

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Chinese Journal of Polymer Science 2007年第6期25卷 545-553页

作者： Li-ming tang Ji Feng Yu Wang Advanced Materials Laboratory Department of Chemical Engineering Tsinghua University Beijing 100084 China

Five secondary amine terminated poly（ester-amine）s （defined as PEA） with controlled molecular structures were synthesized through reacting excessive piperazine with phthalicdiglycol diacrylate （PDDA） and 1,1,1-trimethylolpropane triacrylate （TMPTA） at a constant secondary amine/acrylate group ratio of 1.5/1 and at different PDDA/TMPTA molar ratios. Both IR and ^1H-NMR spectra indicated that all acrylate groups were consumed in the reaction, based on which the structural parameters were calculated from the ^1H-NMR spectra. With decreasing PDDA/TMPTA ratio, the content of secondary amine, degree of branching, molecular weight, Tg and Td increased accordingly. These polymers were further used as both crosslinkers and flexibilizers for a linear epoxy resin E51 to form cured films under ambient condition. The gel content, relative hardness and Tg of the resulting films increased as PEA molecules changed from linear to highly branching structures. Due to the flexibility of PEA molecules, all the films possessed excellent mechanical performance.

关键词： Poly(ester-amine) Molecular structure Epoxy resin Cured film.

Relaxation Dynamics in Condensation on Weighted Scale-Free Networks

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Communications in Theoretical Physics 2008年第1期49卷 252-256页

作者： tang ming LIU Zong-Hua Institute of Theoretical Physics and Department of Physics East China Normal University Shanghai 200062 China

Most of the realistic networks are weighted scale-free networks. How this structure influences the condensation on it is a challenging problem. Recently, we make a first step to discuss its condensation [Phys. Rev. E 74 （2006） 036101] and here we focus on its evolutionary process of phase transition. In order to show how the weighted transport influences the dynamical properties, we study the relaxation dynamics in a zero range process on weighted scale-free networks. We find that there is a hierarchical relaxation dynamics in the evolution and there is a scaling relation between the relaxation time and the jumping exponent. The relaxation dynamics can be illustrated by a mean-field equation. The theoretical predictions are confirmed by our numerical simulations.

关键词： relaxation dynamics condensation scale-free networks

The Complexity and Randomness of Linear Multi-secret Sharing Schemes with Non-threshold Structures

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Acta Mathematicae Applicatae Sinica 2014年第4期30卷 1073-1084页

作者： Chun-ming tang Shu-guang DAI School of Mathematics and Information Science Guangzhou University Key Laboratory of Mathematics and Interdisciplinary Sciences of Guangdong Higher Education Institutes Guangzhou University State Key Laboratory of Information Security School of Information Science and Technology Sun Yat-Sen University

In a linear multi-secret sharing scheme with non-threshold structures, several secret values are shared among n participants, and every secret value has a specified access structure. The efficiency of a multi- secret sharing scheme is measured by means of the complexity a and the randomness . Informally, the com- plexity a is the ratio between the maximum of information received by each participant and the minimum of information corresponding to every key. The randomness is the ratio between the amount of information distributed to the set of users U = {1, …, n} and the minimum of information corresponding to every key. In this paper, we discuss a and of any linear multi-secret sharing schemes realized by linear codes with non-threshold structures, and provide two algorithms to make a and to be the minimum, respectively. That is, they are optimal.

关键词： secret sharing multi-secret sharing scheme non-threshold multi-access structure linear code complexity randomness

Resource allocation algorithm with limited feedback for multicast single frequency networks

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第2期13卷 146-154页

作者： ming-wei tang Xiao-xiang WANG MOE Key Laboratory of Universal Wireless Communications Beijing University of Posts and TelecommunicationsBeijing 100876China

The single frequency network (SFN) can provide a multimedia broadcast multicast service over a large coverage area. However, the application of SFN is still restricted by a large amount of feedback. Therefore, we propose a multicast resource allocation scheme based on limited feedback to maximize the total rate while guaranteeing the quality of service (QoS) requirement of real-time services. In this scheme, we design a user feedback control algorithm to effectively reduce feedback load. The algorithm determines to which base stations the users should report channel state information. We then formulate a joint subcarrier and power allocation issue and find that it has high complexity. Hence, we first distribute subcarriers under the assumption of equal power and develop a proportional allocation strategy to achieve a tradeoff between fairness and QoS. Next, an iterative water-filling power allocation is proposed to fully utilize the limited power. To further decrease complexity, a power iterative scheme is introduced. Simulation results show that the proposed scheme significantly improves system performance while reducing 68% of the feedback overhead. In addition, the power iterative strategy is suitable in practice due to low complexity.

关键词： Multicast Single frequency networks (SFN) Orthogonal frequency division multiplexing access (OFDMA) Resource allocation

A mechanism of defect-enhanced phase transformation kinetics in lithium iron phosphate olivine

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npj Computational Materials 2019年第1期5卷 102-110页

作者： Liang Hong Kaiqi Yang ming tang Department of Materials Science&NanoEngineering Rice UniversityHoustonTX 77005USA

Antisite defects are a type of point defect ubiquitously present in intercalation compounds for energy storage *** they are often considered a deleterious feature,here we elucidate a mechanism of antisite defects enhancing lithium intercalation kinetics in LiFePO_(4) by accelerating the FePO_(4)→LiFePO_(4) phase *** FeLi antisites block Li movement along the[010]migration channels in LiFePO_(4),phase-field modeling reveals that their ability to enhance Li diffusion in other directions significantly increases the active surface area for Li intercalation in the surface-reaction-limited kinetic regime,which results in order-of-magnitude improvement in the phase transformation rate compared to defect-free *** defects also promote a more uniform reaction flux on(010)surface and prevent the formation of current hotspots under galvanostatic(dis)charging *** analyze the scaling relation between the phase boundary speed,Li diffusivity and particle dimensions and derive the criteria for the co-optimization of defect content and particle geometry.A surprising prediction is that(100)-oriented LiFePO_(4) plates could potentially deliver better performance than(010)-oriented plates when the Li intercalation process is *** work suggests tailoring antisite defects as a general strategy to improve the rate performance of phase-changing battery compounds with strong diffusion anisotropy.

关键词： transformation defect kinetics