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Shim coil design for Halbach magnet by equivalent magnetic dipole method

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Chinese Physics B 2018年第10期27卷 300-307页

作者： Jia-Min Wu Zheng Xu pan Guo Jin-feng Qi Yu-Cheng He State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing UniversityChongqing 400044China School of Physics and Electronic Engineering Chongqing Normal UniversityChongqing 401331China

Low-field nuclear magnetic resonance magnet（2 MHz） is required for rock core analysis. However, due to its low field strength, it is hard to achieve a high uniform B0 field only by using the passive shimming. Therefore, active shimming is necessarily used to further improve uniformity for Halbach magnet. In this work, an equivalent magnetic dipole method is presented for designing shim coils. The minimization of the coil power dissipation is considered as an optimal object to minimize coil heating effect, and the deviation from the target field is selected as a penalty function term. The lsqnonlin optimization toolbox of MATLAB is used to solve the optimization problem. Eight shim coils are obtained in accordance with the contour of the stream function. We simulate each shim coil by ANSYS Maxwell software to verify the validity of the designed coils. Measurement results of the field distribution of these coils are consistent with those of the target *** uniformity of the B0 field is improved from 114.2 ppm to 26.9 ppm after using these shim coils.

关键词： equivalent magnetic dipole method shim coils magnetic resonance Halbach magnet

“历久弥新”还是“归于平淡”:结婚时长、夫妻共识与中老年人婚姻满意度

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西北人口 2024年第5期45卷 39-50页

作者：马琦峰杜鹏中国人民大学人口与发展研究中心/老年学研究所北京100872

婚姻是联结家庭的重要纽带,在实施积极应对人口老龄化国家战略与推动新时代家庭家教家风建设高质量发展的双重背景下,关注中老年人婚姻议题具有重要的现实意义。一些观点认为夫妻在历经“七年之痒”后双方的婚姻关系将逐渐趋于稳定、回... 详细信息

婚姻是联结家庭的重要纽带,在实施积极应对人口老龄化国家战略与推动新时代家庭家教家风建设高质量发展的双重背景下,关注中老年人婚姻议题具有重要的现实意义。一些观点认为夫妻在历经“七年之痒”后双方的婚姻关系将逐渐趋于稳定、回归平淡,但事实真的如此吗?基于2014、2018与2020年中国家庭追踪调查(CFPS)的三期非平衡面板数据,运用双向固定效应模型及中介效应模型,分析结婚时长对中老年人婚姻满意度的影响,并探讨夫妻共识在其中所发挥的中介作用。研究结果表明,首先,从基准关系来看,结婚时长会对中老年人婚姻满意度产生显著的线性影响,结婚越久,中老年人的婚姻满意度就越高,这一结论在使用四种不同稳健性检验方法后依旧成立;其次,从群体差异来看,相较于老年、非农户口群体,中年、农业户口群体更有可能在夫妻婚姻延续过程中获得婚姻满意度的提升;最后,从内在机制来看,夫妻共识是结婚时长影响中老年人婚姻满意度的重要作用机制,结婚时长会通过增进女性婚嫁、女性生育与家务责任上的夫妻共识来提升中老年人的婚姻满意度。对此,为进一步推进和谐婚姻家庭建设、改善居民中晚年生活福祉,应加快构建婚姻家庭建设的支持性政策体系,积极宣扬男女平等与责任共担的社会理念,进一步加强和改进婚姻家庭辅导教育工作。

关键词：中老年人结婚时长婚姻满意度夫妻共识机制检验

Dynamic modulation in graphene-integrated silicon photonic crystal nanocavity

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Chinese Physics B 2021年第6期30卷 334-340页

作者： Long-pan Wang Cheng Ren De-Zhong Cao Rui-Jun Lan feng Kang School of Opto-Electronic Information Science and Technology Yantai UniversityYantai 264005China Wenjing College Yantai UniversityYantai 264005China

Silicon-based electro-optic modulators are the key devices in integrated optoelectronics. Integration of the graphene layer and the photonic crystal(PC) cavity is a promising way of achieving compact modulators with high efficiency. In this paper, a high-quality(Q) acceptor-type PC nanocavity is employed to integrate with a single-layer graphene for realizing strong modulation. Through tuning the chemical potential of graphene, a large wavelength shift of 2.62 nm and a Q factor modulation of larger than 5 are achieved. A modulation depth(12.8 dB) of the reflection spectrum is also ***, the optimized PC nanocavity has a large free spectral range of 131.59 nm, which can effectively enhance the flexibility of the modulator. It shows that the proposed graphene-based PC nanocavity is a potential candidate for compact,high-contrast, and low-power absorptive modulators in integrated silicon chips.

关键词： graphene photonic crystal nanocavity tunable

Electrocatalytic oxidation of methanol at platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes

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Chinese Chemical Letters 2010年第3期21卷 337-340页

作者： Ma, Yong Jun pan, Yu Ying Wang, Wei feng Yang, Mei Xia Zhou, Min NW Normal Univ Coll Chem & Chem Engn Key Lab Ecoenvironm Related Polymer Mat Minist EducKey Lab Polymer Mat Gansu Prov Lanzhou 730070 Peoples R China

The electrocatalytic oxidation of methanol at the platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes (Eu-Fe film) was investigated for the first time by cyclic *** with the bare platinum electrode,the results showed that the modified electrode had excellent electrocatalytic activity for the oxidation of methanol;the oxidation peak potential shifted more negatively and the peak current increased about twenty *** electrooxidation of methanol at the modified elect...

关键词： Methanol Electrocatalysis Cyanide-bridged binuclear complexes Europium Chemically modified electrode

MamZ protein plays an essential role in magnetosome maturation process of Magnetospirillum gryphiswaldense MSR-1

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Journal of Oceanology and Limnology 2021年第6期39卷 2082-2096页

作者： Sha WU Qing WANG Xu WANG Ruixue GUO Tongwei ZHANG Yongxin pan feng LI Ying LI Engineering Technology Research Center of Ecological Restoration and Comprehensive Utilization of Coal Mining Collapse Area Anhui ProvinceAnhui Province Key Laboratory of Pollutant Sensitive Materials and Environmental RemediationCollege of Life SciencesHuaibei Normal UniversityHuaibei 235000China State Key Laboratories for Agro-biotechnology China Agricultural UniversityBeijing 100193China Paleomagnetism and Geochronology Laboratory Key Laboratory of Earth and Planetary PhysicsInstitute of Geology and GeophysicsChinese Academy of SciencesFrance-China Joint Laboratory for Evolution and Development of Magnetotactic Multicelluar OrganismsBeijing 100029China

Based on analysis of gene structure of mamXY operon in Magnetospirillum gryphiswaldense strain MSR-1,we constructed a mamZ deletion mutant strain(ΔmamZ)and four complemented strains with different mamZ fragment *** cell phenotypic and physiological parameters were evaluated and compared among the wild-type(WT),mutant,and complemented *** growth rates were not notably different;however,magnetic response(Cmag)and iron uptake ability were significantly lower inΔ***-resolution transmission electron microscopy(HR-TEM)showed that magnetosomes inΔmamZ were small and irregular,and rock magnetic measurements suggested that they contained immature *** comparison to WT of MSR-1,intracellular iron content ofΔmamZ and the complemented strains cultured with 20mmol/L iron source was similar or slightly *** complemented strains were unable to synthesize mature or normal amounts of magnetosomes,apparently because of abnormal expression of the transmembrane domain of MamZ ***-time reverse transcription polymerase chain reaction(RTqPCR)analysis showed that relative transcription levels of mamX and ftsZ-like genes inΔmamZ were higher at 18 h than at 12 h,suggesting that MamXY proteins play cooperative functional roles in the magnetosome maturation *** level of mms6 was significantly upregulated inΔmamZ(incubated at 12 h)and the complemented strains(incubated at 12 and 18 h),refl ecting possible interaction between MamXY and Mms6 proteins during magnetosome *** findings,taken together,demonstrate the essential role of MamZ in the magnetosome maturation process in MSR-1.

关键词： Magnetospirillum gryphiswaldense mamZ deletion mamXY operon magnetosome maturation

Multi-manufacturer drug identification based on near infrared spectroscopy and deep transfer learning

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Journal of Innovative Optical Health Sciences 2020年第4期3卷 39-50页

作者： Lingqiao Li Xipeng pan Wenli Chen Manman Wei Yanchun feng Lihui Yin Changqin Hu Huihua Yang School of Automation Beijing University of Posts and Telecommunications 10 Xitucheng Road Beijing 100876P.R.China School of Computer Science and Information Security Guilin University of Electronic Technology 1 Jinji Road Guilin 541004P.R.China National Institutes for Food and Drug Control 10 Tiantanxili Road Beijing 100050 P.R.China

Near infrared(NIR)spectrum analysis technology has outstanding advantages such as rapid,nondestructive,pollution-free,and is widely used in food,pharmaceutical,petrochemical,agricultural products production and testing *** neural network(CNN)is one of the most successful methods in big data analysis because of its powerful feature ex-traction and abstraction ability,and it is especially suitable for solving multi-classification ***-based transfer learning is a machine learning technique,which migrates para-meters of trained model to the new one to improve the *** transfer learning strategy can speed up the learning efficiency of the model instead of learning from *** view of the difficulty in acquisition of drug NIR spectral data and high labeling cost,this paper proposes three simple but very effective transfer learning methods for multi-manufacturer identification of drugs based on one-dimensional *** with the original CNN,the transfer learning method can achieve better classification performance with fewer NIR spectral data,which greatly reduces the dependence on labeled NIR spectral *** the same time,this paper also compares and discusses three different transfer learning methods,and selects the most suitable transfer learning model for drug NIR spectral data *** with the current popular methods,such as SVM,BP,AE and ELM,the proposed method achieves higher classification accuracy and scalability in multi-variety and multi-manufacturer NIR spectrum classification experiments.

关键词： Near-infrared spectroscopy transfer learning drug identification multi-manufacturer

A Multi-Agent Reinforcement Learning-Based Collaborative Jamming System: Algorithm Design and Software-Defined Radio Implementation

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China Communications 2022年第10期19卷 38-54页

作者： Luguang Wang Fei Song Gui Fang Zhibin feng Wen Li Yifan Xu Chen pan Xiaojing Chu College of Communications Engineering Army Engineering University of PLANanjing 210000China

In multi-agent confrontation scenarios, a jammer is constrained by the single limited performance and inefficiency of practical application. To cope with these issues, this paper aims to investigate the multi-agent jamming problem in a multi-user scenario, where the coordination between the jammers is considered. Firstly, a multi-agent Markov decision process (MDP) framework is used to model and analyze the multi-agent jamming problem. Secondly, a collaborative multi-agent jamming algorithm (CMJA) based on reinforcement learning is proposed. Finally, an actual intelligent jamming system is designed and built based on software-defined radio (SDR) platform for simulation and platform verification. The simulation and platform verification results show that the proposed CMJA algorithm outperforms the independent Q-learning method and provides a better jamming effect.

关键词： multi-agent reinforcement learning intelligent jamming collaborative jamming software-defined radio platform

Template-directed Synthesis of Three Metal Oxalates via 4-Connected Building Units

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Chemical Research in Chinese Universities 2014年第6期30卷 889-893页

作者： TIAN Ruijing WANG Fuxiang DU Chunyu feng Lijuan LIU Ying ZHANG Cailing pan Qinhe Key Study Center of the National Ministry of Education for Tropical Resources Utilization Department of Materials and Chemical Engineering Hainan University Haikou 570228 P. R. China State Key Laboratory of Inorganic Synthesis and Preparative Chemistry Jilin University Changehun 130012 P. R. China

Three novel compounds, [Co（en）3]2[Zr2（C2O4）7]·2H20（HNU-2, en=ethylenediamine）, [Co（NH3）6]· [Ce（CzO4）3（H2O）]·H2O（HNU-3） and [Co（dien）2][Gd（C2On）3]·0.75H2O（HNU-4, dien=dethylenetriamine） were hydro- thermal synthesized based on the templates of [Co（en）3]C13, [C0（NH3）6]C13 and [Co（dien）2]C13, respectively. The Zr4＋ Ce3＋ and Gd3＋ cations are all coordinated by four oxalates to form [M（C2O4）n（H2O）n]m （M=Zr, Ce or Gd; n=0 or 1; m=4 or 5）, which are similar to [In（C2O4）4]5- in NKB-1, and can be regarded as 4-connected building units. The [M（C2O4）a（H2O）n]m units are connected via sharing the bis-bidentate bridging oxalate ligands to form binuclears in HNU-2 and 1D ＂zigzag＂ chains in HNU-3 and HNU-4. cular building units to design 3D open frameworks with It is suggested that these compounds could be used as mole- zeolite topologies.

关键词： Coordination polymer Template-directed synthesis Metal oxalate

Formal Scattering Approach to High-Order Harmonic Generation

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Chinese Physics Letters 1999年第7期16卷 502-504页

作者： GAO Liang-hui LI Xiao-feng GUO Dong-sheng FU pan-ming Laboratory of Optical Physics Institute of Physics&Center for Condensed Matter PhysicsChinese Academy of SciencesBeijing 100080 Department of Physics Southern University and A&M CollegeBaton RougeLouisiana 70813USA

By using the time-independent formal scattering theoretical approach,we develop a nonperturbative quantum electrodynamics theory to describe high-order harmonic generation(HHG).This theory recovers the semi-classical interpretation of Corkum(***.71(1993)1994)and gives the same phenomenological cutoff *** HHG emission rate is expressed as an analytic closed *** also discuss the connection between HHG and the above threshold ionization from the scattering viewpoint.

关键词： form. formal Harmonic