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Journal of Energy Chemistry 2023年第10期85卷 276-287,I0009页

作者： Jing-Feng Hou Jian-Fei Gao Ling-Bin Kong State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of TechnologyLanzhou 730050GansuChina School of Materials Science and Engineering Lanzhou University of TechnologyLanzhou 730050GansuChina

The supercapacitor electrode materials suffer from structure pulverization and sluggish electrode kinetics under high current ***,a unique NiMoO_(4)@Co-B heterostructure composed of highly conductive Co-B nanoflakes and a semiconductive NiMoO_(4) nanorod is designed as an electrode material to exert the energy storage effect on *** formed Mott-Schottky heterostructure is helpful to overcome the ion diffusion barrier and charge transfer resistance during charging and ***,this crystalline-amorphous heterogeneous phase could provide additional ion storage sites and better strain ***,the optimized NiMoO_(4)@Co-B hierarchical nanorods(the mass ratio of NiMoO_(4)/Co-B is 3:1)present greatly enhanced electrochemical characteristics compared with other components,and show superior specific capacity of 236.2 mA h g^(-1)at the current density of 0.5 A g^(-1),as well as remarked rate *** present work broadens the horizons of advanced electrode design with distinct heterogeneous interface in other energy storage and conversion field.

关键词： Crystalline-amorphous heterophase Mott-Schottky heterostructure Energy storage Nickel molybdate

Two-step homogenization for the effective thermal conductivities of twisted multi-filamentary superconducting strand

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Applied Mathematics and Mechanics(English Edition) 2022年第5期43卷 689-708页

作者： Yongbin WANG Huadong YONG Youhe ZHOU department of Mechanics and Engineering Sciences College of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China Key Laboratory of Mechanics on Disaster and Environment in Western China Ministry of Education of ChinaLanzhou UniversityLanzhou 730000China

For the accurate prediction of the effective thermal conductivities of the twisted multi-filamentary superconducting strand,a two-step homogenization method is *** on the distribution of filaments,the superconducting strand can be decomposed into a set of concentric cylinder *** layer is a two-phase composite composed of the twisted filaments and copper *** the first step of homogenization,the representative volume element(RVE)based finite element(FE)homogenization method with the periodic boundary condition(PBC)is adopted to evaluate the effective thermal conductivities of each *** the second step of homogenization,the generalized self-consistent method is used to obtain the effective thermal conductivities of all the concentric cylinder *** accuracy of the developed model is validated by comparing with the local and full-field FE ***,the effects of the twist pitch on the effective thermal conductivities of twisted multi-filamentary superconducting strand are studied.

关键词： superconducting strand multi-filamentary two-step homogenization effective thermal conductivity

Study on risk assessment and factors ranking of the LTE-M communication system

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Transportation Safety and Environment 2023年第4期5卷 45-57页

作者： Xiaochun Wu Yu Gao Weichao Zheng School of Automation Electrical Engineering Lanzhou Jiaotong UniversityAnning West RoadLanzhou 730070GansuChina Communication Center Tianjin Rail Transit Operation Group Co.LtdNo.36Xuefu Industrial ParkTianjin 300000China

To assess the operational safety risk of long-term evolution for the metro(LTE-M)communication system more accurately,the guide maintenance strategy,the improved evidence theory and the multi-attribute ideal reality comparative analysis(MAIRCA)approaches are *** to the features of LTE-M system,the risk evaluation system is *** enhanced structural entropy weight method is used to obtain the ***,it is combined with nine-element fuzzy mathematics to transform the degree of membership,modifying the conflict and fusion rules to solve the confidence degree clashed problem of evidence ***,the system risk grade assessment result is *** the purpose of forming the ranking of indicator importance,the MAIRCA is introduced and the ranking is *** operational state of the metro line is used as the data source in various ways the obtained risk grade increased by 7.12%.It is verified that MAIRCA can be applied to the field of urban rail transit because it has based on the test and *** results show that the method is effective;compared with others,the confidence degree of excellent stability and the ranking result of risk factors is *** influencing indicator with the highest importance is the'equipment failure rate".

关键词： long-term evolution for the metro(LTE-M)system operational safety risk assessment improved evidence theory multi-attribute ideal reality comparative analysis(MAIRCA)method

BIFURCATION ANALYSIS IN A PREDATOR-PREY MODEL WITH AN ALLEE EFFECT AND A DELAYED MECHANISM

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Acta Mathematica Scientia 2023年第3期43卷 1415-1438页

作者：李丹阳刘华张濠天马明叶勇魏玉梅 School of Mathematics and Computer Science Northwest Minzu UniversityLanzhou730000China School of Science Harbin Institute of Technology(Shenzhen)Shenzhen518055China Experimental Teaching department Northwest Minzu UniversityLanzhou730030China

Regarding delay-induced predator-prey models, much research has been done on delayed destabilization, but whether delays are stabilizing or destabilizing is a subtle issue. In this study, we investigate predator-prey dynamics affected by both delays and the Allee effect. We analyze the consequences of delays in different feedback mechanisms. The existence of a Hopf bifurcation is studied, and we calculate the value of the delay that leads to the Hopf bifurcation. Furthermore, applying the normal form theory and a center manifold theorem, we consider the direction and stability of the Hopf bifurcation. Finally, we present numerical experiments that validate our theoretical analysis. Interestingly, depending on the chosen delay mechanism, we find that delays are not necessarily destabilizing. The Allee effect generally increases the stability of the equilibrium, and when the Allee effect involves a delay term, the stabilization effect is more pronounced.

关键词： delays Allee effect Hopf bifurcation stability

Tuning host-guest binding model by different intramolecular alkyl chain lengths in tripodal hosts:An evidence on structure control supramolecular interactions

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Chinese Chemical Letters 2023年第1期34卷 378-381页

作者： Zheng-Hua Zhang You-Ming Zhang Wen-Juan Qu Bingbing Shi Hong Yao Tai-Bao Wei Key Laboratory of Eco-environmental Polymer Materials of gansu Province College of Chemistry and Chemical EngineeringNorthwest Normal UniversityLanzhou 730070China gansu Natural Energy Research Institute Lanzhou 730046China

Supramolecular chemistry has received considerable attention in host-guest *** structureresponse relationship of host-guest recognition system is a meaningful ***,a series of tripodal nitrogen mustard derivatives(TMs)have been developed in this *** rationally design the intramolecular alkyl chain lengths of host,the host-guest binding model have been successfully tuned,which underwent a transformation fromπ-πto multiple hydrogen *** process enhances the host-guest binding force and recognition efficiency.

关键词： Host-guest recognition Supramolecular interactions Fluorescent Intramolecular alkyl chain Aggregation induced emission

Elevation change of the Urumqi Glacier No.1 derived from Sentinel-1A data

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Journal of Mountain Science 2021年第10期18卷 2656-2671页

作者： LIU Jia-liang ZHAO Jun LI Zhong-qin WANG Yan-qiang SHEN Si-min College of Geography and Environmental Science Northwest Normal UniversityLanzhou 730070China State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Tian Shan Glaciological Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Accurate measurements of glacier elevation changes play a crucial role in various glaciological studies related to glacier dynamics and mass balance. In this paper, glacier elevation changes of Urumqi Glacier No.1 between August 2015 and August 2017 were investigated using Sentinel-1 A data and DInSAR technology. Meanwhile, the atmospheric delay error was corrected with the MODIS MOD05L2 products. The weight selection iteration method was applied to calibrate the glacier elevation changes in the mass balance years 2015-2016 and 2016-2017. Finally, the geodetic method was employed to calculate the elevation change values of individual stakes of Urumqi Glacier No.1. Moreover, the elevation change values corrected by the weight selection iteration method were verified. Results showed as follows:(1) the elevation of Urumqi Glacier No.1 glacier affected by atmospheric delay was 1.270 cm from 2015 to 2016. The glacier elevation affected by atmospheric delay from 2016 to 2017 was 1.071 cm.(2) The elevation change value of Urumqi Glacier No.1 was-1.101 m from 2015 to 2016, and the elevation of Urumqi Glacier No.1 decreased by 1.299 m from 2016 to 2017. The overall thickness of Urumqi Glacier No. 1 was thinning.(3) By comparing the elevation change results of individual stakes with corresponding points corrected by the weight selection iteration method, the mean squared errors of difference were 0.343 m and 0.280 m between the two mass balance years, respectively.(4) The accuracy of elevation change in non-glaciated areas was 0.039 m from 2015 to 2016 and 0.034 m from 2016 to 2017. Therefore, it is reliable to use Sentinel-1 A data and the study method proposed in this paper to calculate the elevation change of mountain glaciers with very low horizontal movement.

关键词： Glacier elevation change Urumqi Glacier No.1 DInSAR Cryospheric remote sensing Sentinel-1A

Design and performance improvement of SiNPs@graphene@C composite with a popcorn structure

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Journal of Energy Chemistry 2022年第9期31卷 405-415,I0012页

作者： Hong Dong Feifei Zong Jie Wang Hao Ding Peng Wang Ru Song Ningshuang Zhang Xuchun Cui Shiyou Li School of Petrochemical Technology Lanzhou University of TechnologyLanzhou 730050GansuChina Key Laboratory of Low Carbon Energy and Chemical Engineering of gansu Province Lanzhou 730050GansuChina gansu Engineerin Laboratory of Cathode Material for Lithium-ion Battery Baiyin 730900GansuChina

Silicon anodes are considered to be the most promising alternatives owing to their theoretical specific capacity,which is almost 10 times higher than that of graphite ***,huge volume changes during charging and discharging affect their interface stability,which strongly limits their application in commercial ***,a popcorn-structured silicon-carbon composite(SiNPs@graphene@C),composed of silicon nanoparticles(SiNPs),graphene spheres and pitch-based carbon,is prepared by spraydrying followed by a wet *** resulting SiNPs@graphene@C composite has good flexibility and elastic-strain capacity due to the graphene substrate,and it possesses macrostructural integrity and mechanical stability during cycling due to the rigid carbon–carbon chemical *** a result,it shows a discharge-specific capacity of 481.3 mAh g^(-1)and a capacity retention of 82.9%after 500 cycles at 1 A g^(-1).Besides,the initial coulomb efficiency is increased from 65.7%to 86.5%by pre-lithiation,which improves the feasibility of commercialising the SiNPs@graphene@C composite.

关键词： SiNPs@graphene@C Popcorn structure Pre-lithiation

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纳米切削初始温度对单晶铜微观结构的影响

稀有金属材料与工程 2022年第8期51卷 2839-2849页

作者：靳岚伊廷华谢黎明郭虎赟卢世奇兰州理工大学机电工程学院甘肃兰州730050

纳米切削会造成工件的内部微观缺陷,这种缺陷会引起残余应力的变化进而影响工件的表面质量,而这种缺陷结构与切削层初始温度有密切联系。为降低工件纳米切削加工制造中的缺陷,采用分子动力学的方法,构建了含有切削层的单晶铜纳米切削模... 详细信息

纳米切削会造成工件的内部微观缺陷,这种缺陷会引起残余应力的变化进而影响工件的表面质量,而这种缺陷结构与切削层初始温度有密切联系。为降低工件纳米切削加工制造中的缺陷,采用分子动力学的方法,构建了含有切削层的单晶铜纳米切削模型。首先,通过分析工件结构体积及微观缺陷的变化确定了切削层的适用初始温度;其次,分析了切削层初始温度对切削力的影响,并在不同初始温度和切削力作用下对单晶铜位错和晶格等微观结构的变化进行了分析;最后,通过实验对仿真结果进行了间接验证。结果表明:单晶铜切削层初始温度的可选范围为293~400 K;在此范围内,随着切削层初始温度的升高,切削力大小变化显著,但波动平稳,晶格结构的转变速度也随之增快;当切削层初始温度设在360~390 K范围内时,单晶铜工件的表层微观缺陷相对较少,由此可预测单晶铜工件在此初始温度范围内加工得到的表面质量较高。

关键词：纳米切削切削层初始温度单晶铜微观结构

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结合自适应双透射率和景深变化的去雾方法

Journal of Measurement Science and Instrumentation 2023年第4期14卷 413-424页

作者：林雷杨燕兰州交通大学电子与信息工程学院甘肃兰州730070

为了解决单幅图像去雾算法透射率估计不准确和复原结果偏色等问题,提出一种结合景深变化的自适应双透射率去雾方法。首先,将有雾图像从RGB颜色空间转换到Lab颜色空间,对亮度分量作形态学处理和滤波操作,并结合最大值通道估计出大气光。... 详细信息

为了解决单幅图像去雾算法透射率估计不准确和复原结果偏色等问题,提出一种结合景深变化的自适应双透射率去雾方法。首先,将有雾图像从RGB颜色空间转换到Lab颜色空间,对亮度分量作形态学处理和滤波操作,并结合最大值通道估计出大气光。其次,利用有雾图像的高斯-对数映射实现对无雾图像暗通道的估计,并根据不等式关系得到无雾图像的亮通道,然后估计出双透射率。最后,结合深度图与透射率之间的关系,构建双透射率联合优化的自适应透射率函数,并结合大气散射模型恢复出无雾图像。实验表明,所提方法复原结果颜色自然、去雾彻底、细节信息丰富,且具有较高的视觉对比度。同时,在不同场景中均可获得较好的去雾效果,有效解决了透射率估计不准确和偏色问题。

关键词： Lab颜色空间景深函数映射自适应双透射率夜间图像去雾

Direct Kerr-lens mode-locked Tm:LuYO_(3) ceramic laser

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Chinese Physics B 2023年第11期32卷 493-497页

作者：令维军薛婧雯杨金芳王翀杜晓娟王文婷张明霞路飞平李向兵董忠 gansu All Solid-State Laser Engineering Research Center Tianshui 741001China Engineering Research Center of Integrated Circuit Packaging and Testing Ministry of EducationTianshui 741001China School of Electronic Information and Electrical Engineering Tianshui Normal UniversityTianshui 741001China

A direct Kerr-lens mode-locked Tm:LuYO_(3)ceramic laser without the aid of any mode-locked starting element is reported for the first time. A pulse duration as short as 259 fs and a maximum average output power of 326 m W are obtained at a repetition rate of 97.1 MHz. The corresponding optical spectrum centered at 2053 nm exhibits a bandwidth of 19.8 nm,which indicates the presence of nearly Fourier transform-limited pulses. Such a Kerr-lens mode-locked Tm:LuYO_(3)ceramic laser is a promising ultrashort pulse source, with both the excellent laser characteristics of Tm:LuYO3and the high-power 790 nm laser diode pumping scheme.

关键词： all solid-state laser ultrashort pulse Kerr-lens mode-locked Tm:LuYO_(3)ceramic