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Rotary axis calculation for five-axis FDM printer using a point-fitting optimization method

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Applied Mathematics(A Journal of Chinese Universities) 2022年第2期37卷 258-271页

作者： liu Hao liu Lei SHEN Kai College of Mechanical and Electrical Engineering Nanjing University of Aeronatics and AstronaticsNanjing 210016China

This paper presents an optimization method to compute the rotary axes of a 5-axis FDM printer whose A-and C-axes have large deviations relative to the x-and *** optimization model is designed according to the kinematic model in which a point rotates around a spatial line in the machine coordinate system of the *** model considers the A-and C-axes as two spatial *** is a two-object optimization model including two *** is that the sum of deviations between the measured and computed points should be small;the other is that the deviations should be uniformly distributed for every measured point.A comparison of the new optimization method with conventional error-compensation methods reveals that the former has higher location *** the optimized AC axes,5-axis 3D printing paths are planned for some complex *** analysis and printing samples show that the optimized AC axes satisfy 5-axes FDM printing requirements for nozzles with a diameter of 1.0 mm.

关键词： 3D printing five-axis rotary table location error error calibration

Eliminating mother-to-child transmission of HBV:progress and challenges in China

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Frontiers of Medicine 2020年第1期14卷 21-29页

作者： Wenzhan Jing Jue liu Min liu Department of Epidemiology and Biostatistics School of Public HealthPeking UniversityBeijing 100191China

China has the world’s largest burden of hepatitis B virus(HBV)infection,but the country has made considerable progress in preventing its mother-to-child transmission(MTCT)in the past three *** feat is made possible due to the high coverage of birth-dose hepatitis B vaccine(HepB,>95%),hepatitis B surface antigen(HBsAg)screening for pregnant women(>99%),and hepatitis B immunoglobulin plus HepB for newborns whose mothers are HBsAg positive(>99%).Studies on the optimal antiviral treatment regimen for pregnant women with high HBV-DNA load have also been ***,China still faces challenges in eliminating MTCTof *** overall HBsAg prevalence among pregnant women is considered an intermediate *** prevalence of HBsAg among pregnant women from remote,rural,or ethnic minority areas is higher than that of the national level because of limited health resources and public health education for *** coverage for maternal and child healthcare and immunization services should be improved,especially in western *** of current services to prevent MTCTof HBV with other relevant health services can increase the acceptability,efficiency,and coverage of these services,particularly in remote areas and ethnic minority *** doing so,progress toward key milestones and targets to eliminate hepatitis B as the main public health threat by 2030 can be achieved.

关键词： hepatitis B virus mother-to-child transmission progress challenge

On the Making and Significance of the Universal Declaration of Human Rights

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The Journal of Human Rights 2018年第5期17卷 480-498页

作者：刘杰 chang Guohua(译) Human Rights Research Center Shanghai Academy of Social Sciences 不详

The Universal Declaration of Human Rights was the first common commitment of the international community to human rights. It demonstrated the belief and determination of humanity to maintain peace, democracy and human dignity. The process of formulating the Declaration was difficult. But in the spirit of cooperation,countries finally succeeded in reaching a consensus on human *** making of the Universal Declaration of Human Rights had great value and significance for promoting world peace and development,and it has had a far-reaching impact on the rule of law in international human rights and the development of the human rights legal systems in various countries. A re-examination and analysis of the process of formulating the Universal Declaration of Human Rights will help us understand the purposes and objectives of the Declaration and review the great value of the spirit of the Declaration to the world today.

关键词： Universal Declaration of Human Rights human rights processing of formulating significance

脉冲放电等离子烧结NiAl金属间化合物的组织与性能

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金属热处理 2005年第4期30卷 46-48页

作者：刘耀东连建设吉林大学汽车材料教育部重点实验室

通过脉冲放电等离子烧结技术对经机械合金化法合成的NiAl金属间化合物粉末进行了烧结,研究了NiAl金属间化合物的微观组织和力学性能。结果表明,在较低温度下可制备接近完全致密的NiAl金属间化合物块体材料。

关键词： NiAl金属间化合物机械合金化脉冲放电等离子烧结

3D parallel inversion of time-domain airborne EM data

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Applied Geophysics 2016年第4期13卷 701-711,740页

作者： liu Yun-He Yin chang-Chun Ren Xiu-Yan Qiu chang-Kai College of Geo-Exploration Science and Technology Jilin University Changchun 130026 China

To improve the inversion accuracy of time-domain airborne electromagnetic data, we propose a parallel 3D inversion algorithm for airborne EM data based on the direct Gauss-Newton optimization. Forward modeling is performed in the frequency domain based on the scattered secondary electrical field. Then, the inverse Fourier transform and convolution of the transmitting waveform are used to calculate the EM responses and the sensitivity matrix in the time domain for arbitrary transmitting waves. To optimize the computational time and memory requirements, we use the EM ＂footprint＂ concept to reduce the model size and obtain the sparse sensitivity matrix. To improve the 3D inversion, we use the OpenMP library and parallel computing. We test the proposed 3D parallel inversion code using two synthetic datasets and a field dataset. The time-domain airborne EM inversion results suggest that the proposed algorithm is effective, efficient, and practical.

关键词： airborne EM time domain three-dimensional inversion footprint parallel computing

Electron-nuclear hyperfine coupling in quantum kagome antiferromagnets from first-principles calculation and a reflection of the defect effect

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Science Bulletin 2019年第21期64卷 1584-1591页

作者： Shunhong Zhang Yi Zhou Feng liu Zheng liu Institute for Advanced Study Tsinghua UniversityBeijing 100084China Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China Department of Materials Science and Engineering University of UtahSalt Lake CityUtah 84112USA Collaborative Innovation Center of Quantum Matter Beijing 100084China

The discovery of ideal spin-1/2 kagome antiferromagnets Herbertsmithite and Zn-doped Barlowite represents a breakthrough in the quest for quantum spin liquids(QSLs),and nuclear magnetic resonance(NMR)spectroscopy plays a prominent role in revealing the quantum paramagnetism in these ***,interpretation of NMR data that is often masked by defects can be ***,we show that the most significant interaction strength for NMR,*** hyperfine coupling(HFC)strength,can be reasonably reproduced by first-principles calculations for these proposed *** this method to a supercell containing Cu-Zn defects enables us to map out the variation and distribution of HFC at different nuclear *** predictive power is expected to bridge the missing link in the analysis of the low-temperature NMR data.

关键词： Quantum spin liquid Nuclear magnetic resonance First-principles calculation Defect effect

Mechanistic Study on the Dominant Promotion Effect of Al-/Ti-/Zr-modifications over the VOx/SiO2 UHMWPE Catalysts

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Chinese Journal of Polymer Science 2019年第10期37卷 995-1004,I0004页

作者： Yu-Long Jin Lin liu Yu-Jie Wang Zhen liu Bo-Ping liu College of Materials and Energy South China Agricultural UniversityGuangzhou 510642China School of Chemical Engineering East China University of Science and TechnologyShanghai 200237China

Recently, we reported the first VOx/SiO2 ethylene polymerization catalyst for making Cl-free UHMWPE, and found the dominant promotion effects of Al-/Ti-/Zr-modifications over this catalyst system(Macromol. Chem. Phys. 2017, 218, 1600443). In this work, density functional theory is applied to investigate the underlying mechanism of this remarkable promotion effect of Al-/Ti-/Zrmodifications on a molecular and atomic level. The cluster model with V(Ⅲ) is found to be the most possible active site due to its lowest overall energy barrier for monomer insertion, though the process of C2H4 coordination and the subsequent formation of transition state are most energy favored for V(Ⅱ) species. By modifying one of or both V―O―Si in the active model with V―O―M(M = Al, Ti, or Zr),the energy barrier for the binding of the upcoming C2H4 gets lower(particularly for Al-and Zr-modified catalysts), and the transition state also becomes more stable. Generally, the insertion process of C2H4 gets easier after support Al-/Ti-/Zr-modifications. This dominant promotion effect is partially ascribed to the more enriched positive charge distribution on or nearby the V center, and the narrower energy gap between the LUMO of model catalysts and the HOMO of C2H4 for these modified catalysts also contributes much. In addition, the decreased steric hindrance around the V center should be taken into account for the modified models as well. Furthermore, the Br?nsted acidity of the catalysts is investigated by introducing a pendent hydroxyl group to the model catalysts, which has a close contact with the V center. Similar promotion effect of support modification by Al, Ti, and Zr could still be observed.

关键词： Density functional theory Vanadium-oxides Ethylene polymerization Support modification Mechanism

A QUANTUM MULTI-AGENT BASED NEURAL NETWORK MODEL FOR FAILURE PREDICTION

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Journal of Systems Science and Systems Engineering 2016年第2期25卷 210-228页

作者： Wei Wu Min liu Qing liu Weiming Shen School of Electronic and Information Engineering Tongji University Shanghai 201804 China The Key Laboratory of Embedded System and Service Computing Ministry of EducationTongji University Shanghai 200092 China

An effective prognostic program is crucial to the predictive maintenance of complex equipment since it can improve productivity, prolong equipment life, and enhance system safety. This paper proposes a novel technique for accurate failure prognosis based on back propagation neural network and quantum multi-agent algorithm. Inspired by the extensive research of quantum computing theory and multi-agent systems, the technique employs a quantum multi-agent strategy, with the main characteristics of quantum agent representation and several operations including fitness evaluation, cooperation, crossover and mutation, for parameters optimization of neural network to avoid the deficiencies such as slow convergence and liability of getting stuck to local minima. To validate the feasibility of the proposed approach, several numerical approximation experiments were firstly designed, after which real vibrational data of bearings from the Laboratory of Cincinnati University were analyzed and used to assess the health condition for a given future point. The results were rather encouraging and indicated that the presented forecasting method has the potential to be utilized as an estimation tool for failure prediction in industrial machinery.

关键词： Failure prediction complex equipment quantum-inspired multi-agent algorithm back propagation neural network

Analysis of User's Weight in Microblog Network Based on User Influence and Active Degree

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Journal of Electronic Science and Technology 2012年第4期10卷 368-377页

作者： Jie lian Yun liu Zhen-Jiang Zhang Jun-Jun Cheng Fei Xiong School of Electronic and Information Engineering Beijing Jiaotong University Key Laboratory of Communication and Information Systems (Beijing Jiaotong University) Beijing Municipal Commission of Education

Based on user＇s in-degree distribution, traditional ranking algorithms of user＇s weight usually neglect the considerations of the differences among user＇s followers and the features of user＇s tweets. In order to analyze the factors which impact on user＇s weight, under the analysis of the data collected from SINA Microblog network, this paper discovers that user influence and active degrees are the dominant factors for this issue. The proposed algorithm evaluates user influence by user＇s follower number, the influence of user＇s followers and the reciprocity between users. User＇s active degree is modeled by user＇s participation and the quality of user＇s tweets. The models are tested by different data groups to confirm the parameters for the final calculation. Eventually, this paper compares the computational results with the user＇s ranking order given by the SINA official application. The performance of this algorithm presents a stronger stability on the fluctuant range of the value of user＇s weight.

关键词： HITS algorithm SINA Microblog,user influence user rank.