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一种基于免疫调节和共生进化的神经网络优化设计方法 被引量:32
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作者 张军 刘克胜 王煦法 《计算机研究与发展》 EI CSCD 北大核心 2000年第8期924-930,共7页
利用共生进化原理设计人工神经网络 ,创造性地融入了免疫调节原理中的浓度抑制调节机制以保持个体的多样性 ,提出了基于免疫调节的共生进化网络设计方法 .通过对神经元群体而不是神经网络群体进行进化设计 ,显著地减轻了计算量 ,同时利... 利用共生进化原理设计人工神经网络 ,创造性地融入了免疫调节原理中的浓度抑制调节机制以保持个体的多样性 ,提出了基于免疫调节的共生进化网络设计方法 .通过对神经元群体而不是神经网络群体进行进化设计 ,显著地减轻了计算量 ,同时利用生物免疫原理中的浓度机制和个体多样性保持策略进行免疫调节 ,有效地克服了未成熟收敛现象 ,提高了群体的多样性 ,从而加快优化设计速度 .实验结果表明该方法可高效、准确地设计鲁棒性很强的神经网络 . 展开更多
关键词 共生进化 神经网络 免疫调节 优化 设计方法
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无线通信中自适应调制技术的现状与发展 被引量:5
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作者 刘先桥 杨凡 +1 位作者 阮定良 程刚 《微处理机》 2017年第3期34-37,共4页
简要介绍了无线通信中自适应调制技术的历史、现状和未来发展方向。采用分类对比的方法,重点介绍了不同的无线通信系统中自适应调制的技术演进,并对比分析了各个自适应调制算法的性能特点和适用场景;结合无线通信发展的趋势,阐述了自适... 简要介绍了无线通信中自适应调制技术的历史、现状和未来发展方向。采用分类对比的方法,重点介绍了不同的无线通信系统中自适应调制的技术演进,并对比分析了各个自适应调制算法的性能特点和适用场景;结合无线通信发展的趋势,阐述了自适应调制技术需要解决的核心问题,以期为无线链路的性能优化提供解决思路,为高速率、低时延的无线通信系统设计提供参考。 展开更多
关键词 无线通信 自适应调制 发展演进 高速率 低时延 参考设计
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Nano-Au-decorated hierarchical porous cobalt sulfide derived from ZIF-67 toward optimized oxygen evolution catalysis:Important roles of microstructures and electronic modulation 被引量:1
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作者 Hongyu Gong Guanliang Sun +6 位作者 Wenhua Shi Dongwei Li Xiangjun Zheng Huan Shi Xiu Liang Ruizhi Yang Changzhou Yuan 《Carbon Energy》 SCIE EI CAS CSCD 2024年第5期1-14,共14页
Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable goal.Herein,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au... Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable goal.Herein,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au nanoparticles(NPs)(denoted as HP-Au@CoxSy@ZIF-67)hybrid is synthesized by low-temperature sulfuration treatment.The well-defined macroporous-mesoporous-microporous structure is obtained based on the combination of polystyrene spheres,as-formed CoxSy nanosheets,and ZIF-67 frameworks.This novel three-dimensional hierarchical structure significantly enlarges the three-phase interfaces,accelerating the mass transfer and exposing the active centers for oxygen evolution reaction.The electronic structure of Co is modulated by Au through charge transfer,and a series of experiments,together with theoretical analysis,is performed to ascertain the electronic modulation of Co by Au.Meanwhile,HP-Au@CoxSy@ZIF-67 catalysts with different amounts of Au were synthesized,wherein Au and NaBH4 reductant result in an interesting“competition effect”to regulate the relative ratio of Co^(2+)/Co^(3+),and moderate Au assists the electrochemical performance to reach the highest value.Consequently,the optimized HP-Au@CoxSy@ZIF-67 exhibits a low overpotential of 340 mV at 10 mA cm^(-2)and a Tafel slope of 42 mV dec-1 for OER in 0.1 M aqueous KOH,enabling efficient water splitting and Zn-air battery performance.The work here highlights the pivotal roles of both microstructural and electronic modulation in enhancing electrocatalytic activity and presents a feasible strategy for designing and optimizing advanced electrocatalysts. 展开更多
关键词 Au nanoparticles cobalt sulfide electronic modulation hierarchical porous structure oxygen evolution reaction
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Unraveling the modulation essence of p bands in Co-based oxide stability on acidic oxygen evolution reaction
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作者 Yafei Yang Yihao Xu +8 位作者 Haiquan Liu Qi Zhang Boling Liu Menghua Yang Huan Dai Zunjian Ke Dong He Xiaobo Feng Xiangheng Xiao 《Nano Research》 SCIE EI CSCD 2024年第7期5922-5929,共8页
The oxygen evolution reaction(OER)electrocatalysts,which can keep active for a long time in acidic media,are of great significance to proton exchange membrane water electrolyzers.Here,Ru-Co_(3)O_(4)electrocatalysts wi... The oxygen evolution reaction(OER)electrocatalysts,which can keep active for a long time in acidic media,are of great significance to proton exchange membrane water electrolyzers.Here,Ru-Co_(3)O_(4)electrocatalysts with transition metal oxide Co_(3)O_(4)as matrix and the noble metal Ru as doping element have been prepared through an ion exchange–pyrolysis process mediated by metal-organic framework,in which Ru atoms occupy the octahedral sites of Co_(3)O_(4).Experimental and theoretical studies show that introduced Ru atoms have a passivation effect on lattice oxygen.The strong coupling between Ru and O causes a negative shift in the energy position of the O p-band centers.Therefore,the bonding activity of oxygen in the adsorbed state to the lattice oxygen is greatly passivated during the OER process,thus improving the stability of matrix material.In addition,benefiting from the modulating effect of the introduced Ru atoms on the metal active sites,the thermodynamic and kinetic barriers have been significantly reduced,which greatly enhances both the catalytic stability and reaction efficiency of Co_(3)O_(4). 展开更多
关键词 p-band modulation oxygen evolution reaction STABILITY acidic oxygen evolution reaction(OER)
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时频非平稳地震动模型及结构随机振动应用 被引量:4
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作者 何浩祥 范少勇 闫维明 《振动.测试与诊断》 EI CSCD 北大核心 2019年第6期1189-1197,1358,共10页
地震动具有显著的时域和频域非平稳性,传统的均匀调制地震动模型不能充分表征时频两域的非平稳性,并影响结构随机振动分析的精准度。为了克服上述不足,建立由多峰平滑包络和非平稳噪声信号点乘而成的非均匀调制地震动模型,该模型能够在... 地震动具有显著的时域和频域非平稳性,传统的均匀调制地震动模型不能充分表征时频两域的非平稳性,并影响结构随机振动分析的精准度。为了克服上述不足,建立由多峰平滑包络和非平稳噪声信号点乘而成的非均匀调制地震动模型,该模型能够在时域上充分反映地震动的波动和衰减特性,同时其频谱特征也与真实信号相接近。在此基础上,建立同时以时间和频率为变量的非平稳地震动演变谱随机模型。分析结果表明,以上两种模型在时域和频域的合成精度上均优于均匀调制模型。针对以上地震动随机模型的形式和特点,对传统结构随机振动响应求解方法进行改进。通过算例证明,按照均匀调制模型计算结构随机响应不能充分获得结构时频域的非平稳特性且结果偏于不安全,而利用两种改进模型可以获得更精确的结构响应概率特征和更细致的非平稳性演变过程。 展开更多
关键词 地震动 非平稳 随机振动 强度包络 均匀调制 演变谱
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Tailored heterostructured Ni_(3)N-NiO nano-frameworks for boosting electrocatalytic oxygen evolution via surface-modulated plasma strategy
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作者 Bo Ouyang Haonan Qin +5 位作者 Chao Sun Yilin Deng Ang Li Jipeng Zhu Erjun Kan Rajdeep Singh Rawat 《Nano Research》 SCIE EI CSCD 2024年第9期7909-7917,共9页
The facile reconfiguration of phases plays a pivotal role in enhancing the electrocatalytic production of H2 through heterostructure formation.While chemical methods have been explored extensively for this purpose,pla... The facile reconfiguration of phases plays a pivotal role in enhancing the electrocatalytic production of H2 through heterostructure formation.While chemical methods have been explored extensively for this purpose,plasma-based techniques offer a promising avenue for achieving heterostructured nano-frameworks.However,the conventional plasma approach introduces complexities,leading to a multi-step fabrication process and challenges in precisely controlling partial surface structure modulation due to the intricate interaction environment.In our pursuit of heterostructures with optimized oxygen evolution reaction(OER)behavior,we have designed a facile auxiliary insulator-confined plasma system to directly attain a Ni_(3)N-NiO heterostructure(hNiNO).By meticulously controlling the surface heating process during plasma processing,such approach allows for the streamlined fabrication of hNiNO nano-frameworks.The resulting nano-framework exhibits outstanding catalytic performance,as evidenced by its overpotential of 320 mV at a current density of 10 mA·cm^(-2),in an alkaline environment.This stands in stark contrast to the performance of NiO-covered Ni_(3)N fabricated using the conventional plasma method(sNiNO).Operando plasma diagnostics,coupled with numerical simulations,further substantiates the influence of surface heating due to auxiliary insulator confinement of the substrate on typical plasma parameters and the formation of the Ni_(3)N-NiO nanostructure,highlighting the pivotal role of controlled surface temperature in creating a high-performance heterostructured electrocatalyst. 展开更多
关键词 structural modulation auxiliary insulator-confined plasma surface heating control HETEROSTRUCTURE electrocatalytic O_(2) evolution
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光谱色散匀滑光束焦斑动态特性的实验研究 被引量:3
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作者 贺军 李平 +3 位作者 柴向旭 王礼权 王冠中 田晓琳 《中国激光》 EI CAS CSCD 北大核心 2022年第11期87-94,共8页
光谱色散匀滑(SSD)光束的焦斑动态特性是联系激光等离子体不稳定性(LPI)和高功率激光装置性能的重要纽带。为了提升对SSD光束聚焦性能的认知,基于条纹相机的光成像系统,开展了带时间分辨的光束测试实验,获得了SSD光束的焦斑动态图像和... 光谱色散匀滑(SSD)光束的焦斑动态特性是联系激光等离子体不稳定性(LPI)和高功率激光装置性能的重要纽带。为了提升对SSD光束聚焦性能的认知,基于条纹相机的光成像系统,开展了带时间分辨的光束测试实验,获得了SSD光束的焦斑动态图像和演化规律。实验直接演示了SSD光束的焦斑动态特性,沿SSD扫动方向的焦斑图像具有典型的周期余弦扫动特征,扫动幅度、周期等特征与调制频率相关,而垂直SSD扫动方向的焦斑的时空分布则较为杂乱,不再具有典型的余弦扫动特征。另外,实验也表明,SSD光束焦斑有强烈的幅度调制,且调制具有明显的区域效应,调制的大小和SSD扫动方向以及调制频率密切相关。SSD光束焦斑的动态分布特性对光束匀滑性能的分析和优化具有重要指导意义。 展开更多
关键词 激光光学 焦斑特性 光谱色散匀滑 幅度调制 动态演化
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混合滤波器优化的雷达信号调制识别算法 被引量:2
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作者 高敬鹏 毛新蕊 +1 位作者 吴若无 卢毅 《哈尔滨工程大学学报》 EI CAS CSCD 北大核心 2022年第10期1522-1531,共10页
针对传统雷达信号调制识别方法中存在样本数少,卷积神经网络难训练,导致调制识别率低的问题,本文提出一种基于混合滤波器优化的雷达信号调制识别算法。本文算法依据矩阵映射理论,设计混合滤波器,构建特征值映射网络模型,提取雷达信号特... 针对传统雷达信号调制识别方法中存在样本数少,卷积神经网络难训练,导致调制识别率低的问题,本文提出一种基于混合滤波器优化的雷达信号调制识别算法。本文算法依据矩阵映射理论,设计混合滤波器,构建特征值映射网络模型,提取雷达信号特征,融合差分进化思想与柯西变异机制,提出混合蝴蝶优化算法,寻优支持向量机组合控制参数,实现雷达信号调制识别。仿真结果表明:类样本数仅为60的训练条件下,在0 dB下比传统算法识别率高5%左右,说明本文所提算法在低信噪比下能有效区分9种雷达信号的调制方式,具备良好分类和抗噪声性能,为电子对抗提供新思路。 展开更多
关键词 调制识别 雷达信号处理 混合滤波器 混合蝴蝶优化算法 特征值映射网络 差分进化 柯西变异 支持向量机 小样本
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Electron modulation by atomic Ir site decoration in porous Co/N co-doped carbon for electrocatalytic hydrogen evolution 被引量:1
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作者 Youkui Zhang Zitong Yan +7 位作者 Yeli Gao Yaqin Fu Wenhao Li Yunxiang Lin Chuanqiang Wu Yujuan Pu Tao Duan Li Song 《Nano Research》 SCIE EI CSCD 2023年第2期2011-2019,共9页
The rational design of materials at atomic scale as efficient and stable electrocatalysts for hydrogen evolution reaction(HER)is critical for energy conversion.Herein,we report a novel hybrid nanostructure with iridiu... The rational design of materials at atomic scale as efficient and stable electrocatalysts for hydrogen evolution reaction(HER)is critical for energy conversion.Herein,we report a novel hybrid nanostructure with iridium(Ir)and cobalt(Co)atomic pair configuration anchored in porous nitrogen-doped carbon(pNC)nanosheets(denoted as IrCo-pNC)for electrocatalytic HER.Experimental investigations and theoretical calculations reveal that the interaction between Ir and Co species in pNC promotes electron accumulation and depletion around isolated Ir and Co atoms,respectively,resulting in a local asymmetry electron density distribution.Density functional theory calculations also suggest that the electrons transfer from Co to adjacent Ir atom causing the down shift of the d-band center of Ir 5d in IrCo-pNC catalyst,thus optimizing the adsorption of hydrogen on Ir sites.The as-prepared IrCo-pNC exhibits significant HER performance with an overpotential of 21 mV to achieve a current density of 10 mA·cm^(−2)in 0.5 M H2SO4.This work provides insight into the role of asymmetry electron density distribution in nanomaterials in regulating HER electrocatalysis. 展开更多
关键词 electron modulation iridium decoration porous carbon ELECTROCATALYSIS hydrogen evolution reaction
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Mn-doping induced electronic modulation and rich oxygen vacancies on vertically grown NiFe2O4 nanosheet array for synergistically triggering oxygen evolution reaction 被引量:1
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作者 Yonghao Gan Meilin Cui +8 位作者 Xiaoping Dai Ying Ye Fei Nie Ziteng Ren Xueli Yin Baoqiang Wu Yihua Cao Run Cai Xin Zhang 《Nano Research》 SCIE EI CSCD 2022年第5期3940-3945,共6页
Large-scale electrolysis of water to produce high-purity hydrogen is one of the effective ways to solve the energy crisis and environmental pollution problems.However,efficient,cheap and stable catalysts are one of th... Large-scale electrolysis of water to produce high-purity hydrogen is one of the effective ways to solve the energy crisis and environmental pollution problems.However,efficient,cheap and stable catalysts are one of the bottlenecks for industrial application in water splitting.Herein,a facile one-step hydrothermal process was applied to fabricate Mn-doped nickel ferrite nanosheets(Mn-NiFe_(2)O_(4))which shown a low overpotential of 200 mV at 50 mA·cm^(-2)and a small Tafel slope of 47 mV·dec^(-1),together with a prominent turnover frequency(TOF)value(0.14 s^(-1))and robust stability.The in-situ UV-vis spectroscopy unveiled the surface reconstruction to generate NiOOH as active sites during oxygen evolution reaction(OER).The excellent electrocatalytic activity of Mn-NiFe_(2)O_(4)is attributed to the vertically grown nanosheets for exposure more active sites,rich oxygen vacancies,and the hybridization between Ni 3d and O 2p orbitals caused by Mn doping.This work should provide a facile strategy by Mn-doping to simultaneously engineer oxygen vacancies and electronic structure for synergistically triggering oxygen evolution reaction. 展开更多
关键词 Mn doping NiFe_(2)O_(4)nanosheets oxygen vacancies electronic modulation oxygen evolution reaction
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Formation of hierarchical Co-decorated Mo_(2)C hollow spheres for enhanced hydrogen evolution 被引量:1
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作者 Yi-Zhong Wang Yi-Ming Ding +3 位作者 Cai-Hong Zhang Bo-Wen Xue Nian-Wu Li Le Yu 《Rare Metals》 SCIE EI CAS CSCD 2021年第10期2785-2792,共8页
Water electrolysis has been regarded as a promising technology to produce clean hydrogen fuel with high purity. However, large-scale water electrolysis has been greatly hindered due to the lack of non-noble metal cata... Water electrolysis has been regarded as a promising technology to produce clean hydrogen fuel with high purity. However, large-scale water electrolysis has been greatly hindered due to the lack of non-noble metal catalysts with high catalytic performance. Benefitting from unique hollow structures with large surface area and adjustable chemical compositions, hollow design plays an important role in improving the electrocatalytic performance for hydrogen evolution reaction(HER). Herein, we report an effective multi-step strategy to prepare hierarchical Co-decorated Mo_(2)C hollow spheres(CMCHSs) as electrocatalyst for HER. To be specific, the preparation process involves a metal-chelated polymerization and a subsequent surface modulation process. Owing to the unique hollow structure and incorporation of Co species,the as-prepared CMCHSs demonstrate largely enhanced HER performance with a low overpotential of 139 mV at the current density of 10 m A·cm^(-2) and good cycling durability in acid. The present research work highlights a new feasible strategy for the design of HER electrocatalyst via hollow designs and surface engineering. 展开更多
关键词 Mo_(2)C Hollow design Surface modulation Hydrogen evolution reaction
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Design and modulation principles of molybdenum carbide-based materials for green hydrogen evolution 被引量:1
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作者 Jing-Qi Chi Min Yang +3 位作者 Yong-Ming Chai Zhi Yang Lei Wang Bin Dong 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2020年第9期398-423,I0012,共27页
The green production of hydrogen from electrocatalytic water splitting is an important base and promising direction for the future of the large-scale application of hydrogen energy.The key of green hydrogen evolution ... The green production of hydrogen from electrocatalytic water splitting is an important base and promising direction for the future of the large-scale application of hydrogen energy.The key of green hydrogen evolution depends on the development of low-cost and highly active electrocatalysts.Molybdenum carbides(MoxC),as a typical of earth-abundant transition-metal material,have accumulated great attention due to their low cost,earth abundance,electrical conductivity,similar d-band state to Pt,and regulated morphology/electronic structures.In this paper,recent researches focusing on MoxC for efficient HER in a wide pH range are summarized from respects of modulation of unique morphology,electronic structure,and electrode interface step by step.Briefly,modulation of morphology influence the apparent activity of catalyst,modulation of electronic structure of active sites by heteroatom doping and designing heterointerface boost intrinsic HER kinetics,and modulation of electrode interface via hybridization of MoxC structures with carbon materials can ensure the fast electron transfer and boost the activity.Besides the above methods discussed,perspective and challenges of designing MoxC as the substitute of Pt-based electrocatalyst for practical hydrogen generation in a wide pH range are pointed out. 展开更多
关键词 Molybdenum carbides CLASSIFICATION ELECTROCATALYST modulation strategy Hydrogen evolution
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两种低密度校验码译码算法的性能比较与分析 被引量:1
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作者 宋挥师 张平 《北京邮电大学学报》 EI CAS CSCD 北大核心 2004年第z2期217-221,共5页
研究了迭代译码算法和迭代接收算法性能,提出了64 QAM调制时伪对数似然比率的简化计算公式,并利用高斯近似密度进化技术分析了两种译码算法的性能差异.
关键词 低密度校验码 调制 密度进化 性能
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时间调制矩形平面阵超低副瓣方向图综合 被引量:1
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作者 种山 李钢 《系统工程与电子技术》 EI CSCD 北大核心 2011年第7期1473-1477,共5页
将时间调制技术引入到常规矩形平面阵当中,可构成时间调制矩形平面阵。利用差分进化算法和Tseng-Cheng方法对静态激励幅度和高速射频开关的工作时序进行设计和优化,可以在较低的激励幅度动态范围比的情况下在中心频率处综合超低副瓣方向... 将时间调制技术引入到常规矩形平面阵当中,可构成时间调制矩形平面阵。利用差分进化算法和Tseng-Cheng方法对静态激励幅度和高速射频开关的工作时序进行设计和优化,可以在较低的激励幅度动态范围比的情况下在中心频率处综合超低副瓣方向图,同时有效抑制边带辐射。通过对一个10×10的矩形平面阵进行仿真得到了-50 dB的超低副瓣,同时边带辐射得到了有效抑制,验证了本文方法的有效性。 展开更多
关键词 时间调制 天线阵 超低副瓣 差分进化
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Electronic structure modulation with ultrafine Fe_(3)O_(4) nanoparticles on 2D Ni-based metal-organic framework layers for enhanced oxygen evolution reaction
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作者 Wei Huang Chao Peng +7 位作者 Jing Tang Fangyuan Diao Murat Nulati Yesibolati Hongyu Sun Christian Engelbrekt Jingdong Zhang Xinxin Xiao Kristian S.Mølhave 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第2期78-88,共11页
Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanopart... Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanoparticles(diameter:6±2 nm)are homogeneously immobilized on 2D Ni based MOFs(Ni-BDC,thickness:5±1 nm)to improve the OER stability.Electronic structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe_(3)O_(4) nanoparticles on Ni-BDC.The optimal Fe_(3)O_(4)/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm^(-2),a Tafel slope of 47.8 mV dec^(-1) and a considerable catalytic durability of more than 40 h(less than 5 h for Ni-BDC alone).DFT calculations confirm that the active sites for Fe_(3)O_(4)/Ni-BDC are mainly contributed by Fe species with a higher oxidation state,and the potential-determining step(PDS)is the formation of the adsorbed O*species,which are facilitated in the composite. 展开更多
关键词 Fe_(3)O_(4)nanoparticles 2D Ni-BDC Aggregation Electronic structure modulation Oxygen evolution reaction
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Shaped patterns synthesis in time-modulated antenna arrays with static uniform amplitude and phase excitations
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作者 Gang LI Shiwen YANG +1 位作者 Ming HUANG Zaiping NIE 《Frontiers of Electrical and Electronic Engineering in China》 CSCD 2010年第2期179-184,共6页
Abstract A novel approach for the synthesis of shaped beam patterns in time-modulated antenna arrays(TMAAs)with static uniform amplitude and phase excitations is proposed in this paper.Based on the sideband radiation ... Abstract A novel approach for the synthesis of shaped beam patterns in time-modulated antenna arrays(TMAAs)with static uniform amplitude and phase excitations is proposed in this paper.Based on the sideband radiation in TMAAs,shaped beam patterns can be realized by only controlling the switch-on time sequences of the TMAAs.Differential evolution(DE)algorithm is adopted to optimize the time modulation parameters to obtain the desired flat-top and cosecant-squared beams and to suppress the sidelobe levels(SLLs).Simulation results of a time-modulated linear array(TMLA)and a timemodulated semicircular array(TMSA)demonstrate the effectiveness of the proposed approach for the synthesis of shaped beam patterns from TMAAs. 展开更多
关键词 antenna arrays time modulation shaped pattern differential evolution
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Efficient Electronic Modulation of g-C_(3)N_(4)Photocatalyst by Implanting Atomically Dispersed Ag_(1)-N_(3)for Extremely High Hydrogen Evolution Rates
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作者 Guanchao Wang Ting Zhang +5 位作者 Weiwei Yu Zhe Sun Xiaowa Nie Rui Si Yuefeng Liu Zhongkui Zhao 《CCS Chemistry》 CAS 2022年第8期2793-2805,共13页
Developing an efficientmethod to improve the photocatalytic efficiency of graphitic carbon nitride(g-C3 N4)is of great significance for solar H2 production.Electronic structure modulation has been considered one of th... Developing an efficientmethod to improve the photocatalytic efficiency of graphitic carbon nitride(g-C3 N4)is of great significance for solar H2 production.Electronic structure modulation has been considered one of the most crucial strategies to improving the photocatalytic efficiency of g-C_(3)N_(4),but how to efficiently modulate its electronic structure remains a huge challenge.Herein,we,for the first time,report a facile and highly-efficient approach to modulating the electronic structure of g-C_(3)N_(4)through single Ag atom implantation with a Ag_(1)-N_(3)coordination configuration into the g-C_(3)N_(4)framework. 展开更多
关键词 single-atomsilver graphitic carbon nitride electronic structure modulation hydrogen evolution photocatalysis
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初始均匀波列调制演化的实验研究
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作者 张威 马玉祥 +1 位作者 董国海 赫岩丽 《工程力学》 EI CSCD 北大核心 2013年第3期464-469,共6页
该文运用实验的方法对初始均匀波列在静水条件下的演变做出了详细的研究,分析了不同波陡情况下的均匀波列沿水槽的演变过程。实验结果表明由于不稳定波前的作用,初始均匀波列的群性逐渐增大,并且在相同传播范围内波长越小,波浪不稳定性... 该文运用实验的方法对初始均匀波列在静水条件下的演变做出了详细的研究,分析了不同波陡情况下的均匀波列沿水槽的演变过程。实验结果表明由于不稳定波前的作用,初始均匀波列的群性逐渐增大,并且在相同传播范围内波长越小,波浪不稳定性表现得越明显,不稳定边频也增加的越快。通过小波变换的方法提取波列的瞬时频率来分析波浪的频率调制现象,分析结果表明:频率调制是从局部开始的,并且发生频率调制的时间段随着传播距离的增加而增加;另外实验中虽然没有有效频带下移发生,但是还发现了局部频带下移,这也说明频带下移是从局部开始的。 展开更多
关键词 波浪 调制演化 频谱 小波变换 瞬时频率
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高斯光束在外加空间调制电场的光折变晶体中的演化 被引量:7
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作者 陈守满 石顺祥 董洪舟 《光学学报》 EI CAS CSCD 北大核心 2007年第1期166-170,共5页
研究了高斯光束在外加空间调制电场的光折变晶体中的演化,结果表明,在不同的外加调制电场作用下高斯光束的光场分布会随着外电场变化而被调制。重点研究了同相位和反相位以及相位差为π/2的高斯光束在外加空间调制电场的光折变晶体中的... 研究了高斯光束在外加空间调制电场的光折变晶体中的演化,结果表明,在不同的外加调制电场作用下高斯光束的光场分布会随着外电场变化而被调制。重点研究了同相位和反相位以及相位差为π/2的高斯光束在外加空间调制电场的光折变晶体中的相互作用,在外加空间分布线性增加电场作用下出现了许多新的实用特性,通过调整外加电场分布,可以让两同相位相干光靠得更近而不发生融合,也可以让两靠得很近的反相位光束可控偏转,还可以控制相位差为π/2的两相干光束进行能量转移。这种连续变化的电场可以用阶梯分布的电场替代,为工程实现提供了可能。 展开更多
关键词 非线性光学 高斯光束 空间调制电场 演化 相互作用
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表界面调控电催化析氧反应 被引量:4
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作者 卢明龙 张晓云 +2 位作者 杨帆 王练 王育乔 《化学进展》 SCIE CAS CSCD 北大核心 2022年第3期547-556,共10页
开发高效绿色清洁能源已引起研究者们的广泛关注。电解水是一种大规模且可持续生产高纯氢能源技术。然而,阳极析氧反应电催化剂的高过电位和不稳定性制约了电解水技术的大规模应用,合理设计电催化剂的结构可显著优化其反应热力学和动力... 开发高效绿色清洁能源已引起研究者们的广泛关注。电解水是一种大规模且可持续生产高纯氢能源技术。然而,阳极析氧反应电催化剂的高过电位和不稳定性制约了电解水技术的大规模应用,合理设计电催化剂的结构可显著优化其反应热力学和动力学,提高电解水技术的能量转换效率。表界面是电催化反应发生的主要场所,通过调控电催化剂表面的本征结构或构筑异质界面等系列表界面化学工程对电催化剂进行改性,可以有效改善材料的催化活性和稳定性。本文概述了当前表界面调控策略在电催化析氧反应中的研究进展,重点介绍了表界面调控层状双金属氢氧化物、钙钛矿型氧化物、尖晶石型化合物及合金材料的研究现状,阐述了高效稳定析氧反应电催化剂的设计思路。讨论了表界面调控策对催化剂表界面微结构和电子态的影响以及设计新型析氧反应电催化剂中面临的问题。最后,展望了表界面调控应用于析氧反应电催化剂的前景。 展开更多
关键词 表界面调控 电子传输 电催化 微观结构 析氧反应
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