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Science China(Technological Sciences) 2021年第7期64卷 1447-1458页

作者： yu aimei LI Qiang MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing210094China

Conductive polymer composites(CPCs) as the thermo-sensitive materials have attracted much attention in thermal control field due to their reliable self-regulating behaviors, high efficiency and mechanical flexibility. However, the development of these materials needs to manage the normal conflicting requirements, such as effective heating performance and good self-regulating capability. This paper presents a series of novel CPCs material having different amounts of hybrid fillers of multi-walled carbon nanotubes(CNTs) and carbon black(CB). The positive temperature coefficient intensity is enhanced to 105.2, and the roomtemperature resistivity is optimized to 320 ? cm. Besides, the Curie temperatures are regulated to room-temperature range by incorporating the low-melting-point blend matrix into the poly(ethylene-co-vinyl acetate)/CNTs/CB composite. The thermalcontrol experiment demonstrates that CPCs-heating elements can adjust the equilibrium temperature of controlled equipment near their Curie temperatures without any control methods. Compared with the ordinary resistor, the CPCs materials have the remarkable adaptive thermal control behavior. Furthermore, the temperature control capability is particularly prominent in the changing environment temperature. The CPCs as a safe and reliable adaptive heating element is potential to replace the conventional active thermal control means.

关键词： positive temperature coefficient room-temperature Curie point adaptive thermal control CPCs materials

Lower Bounds on the(Laplacian) Spectral Radius of Weighted Graphs

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Chinese Annals of Mathematics,Series B 2014年第4期35卷 669-678页

作者： aimei yu Mei LU Department of Mathematics Beijing Jiaotong University Department of Mathematical Sciences Tsinghua University

The weighted graphs, where the edge weights are positive numbers, are considered. The authors obtain some lower bounds on the spectral radius and the Laplacian spectral radius of weighted graphs, and characterize the graphs for which the bounds are attained. Moreover, some known lower bounds on the spectral radius and the Laplacian spectral radius of unweighted graphs can be deduced from the bounds.

关键词： Weighted graphs Adjacency matrix Laplacian matrix Spectral radius Lower bounds

Study on positive temperature coefficient of resistivity of co-doped BaTiO_3 with Curie temperature in room temperature region

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Science China(Technological Sciences) 2019年第5期62卷 811-819页

作者： yu aimei LI Qiang FAN DeSong ZHANG HongLiang MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Energy and Power EngineeringNanjing University of Science & Technology

As a temperature self-regulating heater material, the doped BaTiO_3 exhibits an attractive application perspective in the thermal management of electrical devices. However, the high Curie temperature does not meet the requirement in the thermal control application. In this work,(Ba_(0.997-x)Ce_(0.003)Sr_x)(TiNb_(0.002))O_3(x=0.2, 0.3, 0.35, abbreviated as BCSTNs) ceramics were prepared by the solid-state reaction method. The purpose of doping different content of strontium is to shift the Curie temperature of BaTiO_3-based ceramic to the ambient temperature region, maintaining excellent PT_C effect and low room-temperature resistivity by codoped cation ions in Ba-and Ti-site. The influences of sintering temperature and soak time on the microstructure as well as electrical properties of BCSTNs ceramics have been studied. The X-ray diffraction reveals that the composition with x=0.35 exhibits the coexistence of tetragonal and cubic lattice symmetries, confirmed by the Rietveld structure refinement. The dense microstructure with average grain sizes 0.84–7.87 μm was observed for BCSTN ceramics. Temperature-resistivity measurements demonstrate that T_C of the ceramics with x=0.35 shifted to the room temperature region. Additionally, the BCSTN ceramic with heavy doping Sr exhibits relative low room-temperature resistivity and the resistance jump greater than 2.0 orders of magnitude.

关键词： electrical heating Co-doped BaTiO3 curie temperature positive temperature coefficient of resistivity

On the Distance Signless Laplacian Spectral Radius of Bicyclic Graphs

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Journal of Mathematical Research with Applications 2023年第3期43卷 289-302页

作者： Nannan XU aimei yu School of Mathematics and Stastics Beijing Jiaotong University

The distance signless Laplacian matrix of a connected graph G is defined as Q(G)=Tr(G)+D(G), where Tr(G) is the diagonal matrix of the vertex transmissions in G and D(G) is the distance matrix of G. The largest eigenvalue of the distance signless Laplacian matrix is called the distance signless Laplacian spectral radius of G. In this paper, we determine the unique graph with the maximum distance signless Laplacian spectral radius among all the bicyclic graphs with given order.

关键词： distance signless Laplacian matrix spectral radius bicyclic graph

A Characterization of Bicyclic Signed Graphs with Nullity n-7

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Journal of Mathematical Research with Applications 2015年第1期35卷 1-10页

作者： Guojun LI aimei yu Department of Mathematics Beijing Jiaotong University

Let Γ be a signed graph and A(Γ) be the adjacency matrix of Γ. The nullity ofΓ is the multiplicity of eigenvalue zero in the spectrum of A(Γ). In this paper, the connected bicyclic signed graphs(including simple ... 详细信息

关键词： nullity signed graph bicyclic graph adjacency matrix

新型PTC材料的阻温特性及其热控性能的研究

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工程热物理学报 2023年第2期44卷 525-531页

作者：余爱梅李强南京理工大学能源与动力工程学院南京210094 电子设备热控制工信部重点实验室南京210094

正温度系数(Positive temperature coefficient, PTC)材料是一种电阻随温度变化的热控功能材料,然而,传统的PTC材料由于高室温电阻率以及负温度系数效应而限制了其在电子设备热控领域的应用。本文基于石蜡/乙烯–醋酸乙烯酯共聚物混合基... 详细信息

正温度系数(Positive temperature coefficient, PTC)材料是一种电阻随温度变化的热控功能材料,然而,传统的PTC材料由于高室温电阻率以及负温度系数效应而限制了其在电子设备热控领域的应用。本文基于石蜡/乙烯–醋酸乙烯酯共聚物混合基体,利用多壁碳纳米管和炭黑杂化填料的协同效应制备得到具有室温居里点、低室温电阻率和优异电阻正温度效应的新型PTC材料。研究了基体配比、填料含量对室温电阻率和PTC性能的影响,并采用羧甲基纤维素对其负温度系数效应现象进行改善。此外,对新型PTC材料的自适应热控性能进行了研究和分析。研究发现:与普通的电阻加热器相比,PTC加热器具有自适应控温能力,并且在没有任何外部控制系统的条件下可以将被控设备的温度控制在正常工作温度范围内。

关键词：正温度系数效应 PTC电阻居里温度自适应控温

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第二大特征值小于1的一类图

应用数学学报 2008年第4期31卷 624-629页

作者：余爱梅北京交通大学数学系北京100044

设G是简单连通图,λ_2(G)为G的第二大特征值.本文给出了所有使λ_2(G)<1且含有唯一三角形的图.

关键词：第二大特征值非二部图围长

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船用变压器噪声控制方法及试验研究

电力系统装备 2023年第4期 116-118页

作者：于爱梅泰州海田电气制造有限公司江苏泰州225300

文章对船用变压器噪声产生因素及传播进行分析,并给出有效措施,从变压器器身、附件、安装方式及安装环境提出了控制方法.

关键词：船用变压器噪声控制方法

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C_2(4,k)中的强支撑可迹图

数学年刊（A辑） 2018年第1期39卷 53-62页

作者：余爱梅马仁森王可可孔将旭北京交通大学数学系北京100044 Department of Mathematics Embry-Riddle Aeronautical University 中国计量大学理学院杭州310018

设2≤h≤3,l>0,k≥0是整数,C_h(l,k)是由h-边连通简单图组成的集合,图G∈C_h(l,k)当且仅当对图G的任意一个二边割或三边割X,图G-X的每个分支都至少有︱V(G)-k︱/l个点.设e=u_1v_1和e'=u_2v_2是图G的两条边.若e≠e',G(e,e')是将图G中的边... 详细信息

设2≤h≤3,l>0,k≥0是整数,C_h(l,k)是由h-边连通简单图组成的集合,图G∈C_h(l,k)当且仅当对图G的任意一个二边割或三边割X,图G-X的每个分支都至少有︱V(G)-k︱/l个点.设e=u_1v_1和e'=u_2v_2是图G的两条边.若e≠e',G(e,e')是将图G中的边e=u_1v_1和e'=u_2v_2分别用路u_1v_ev_1和u_2v_e'v_2替换得到的图(其中,v_e,v_e'是不在V(G)中的两个新的点).若e=e',G(e,e')是将图G中的边e=u_1v_1用路u_1v_ev_1替换得到的图,也记作G(e).若对任意的e,e'∈E(G),G(e,e')都有支撑(v_e,v_e')迹,则称图G是强支撑可迹的.作者证明了,若图G∈C_2(4,k)且|V(G)|>5k,则要么图G是强支撑可迹图,要么存在e,e'∈E(G),使得G(e,e')可以收缩成一个有限图类F中的图.当k=4时,F被完全确定了.

关键词：强支撑可迹图可折叠图简化图

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屏气指数与脑梗死的相关性研究

中国中西医结合急救杂志 2020年第3期27卷 318-320页

作者：仲婷婷王刚班旭英禹爱梅薛茜王琼邹玉安河北北方学院附属第一医院神经内科河北张家口075000

目的分析屏气指数(HBI)与脑梗死(CI)的相关性.方法选择2016年6月至2017年6月河北北方学院附属第一医院收治的120例CI患者作为观察组,再根据CI患者入院时的神经功能缺损程度评分(NHISS)分为轻度(NHISS≤4分,51例)、中度(NHISS 4~20分,4... 详细信息

目的分析屏气指数(HBI)与脑梗死(CI)的相关性.方法选择2016年6月至2017年6月河北北方学院附属第一医院收治的120例CI患者作为观察组,再根据CI患者入院时的神经功能缺损程度评分(NHISS)分为轻度(NHISS≤4分,51例)、中度(NHISS 4~20分,45例)、重度(>20分,24例)受损组.以同期在本院体检的120例健康志愿者为健康对照组.采用经颅多普勒超声(TCD)检查行屏气试验,比较各组屏气指数(HBI)的差异;采用全自动生化分析检测血浆同型半胱氨酸(Hcy)水平;采用Pearson相关性分析法分析HBI与Hcy的相关性.结果观察组左、右两侧大脑中动脉(MCA)的HBI水平均明显低于健康对照组(左侧MCA:1.12±0.25比1.67±0.46,右侧MCA:1.03±0.31比1.74±0.53,均P中度受损组>重度受损组(左侧MCA:1.32±0.23>1.01±0.35>0.82±0.16;右侧MCA:1.26±0.30>0.99±0.38>0.78±0.21);而Hcy水平明显明显升高,轻度受损组Hcy<中度受损组<重度受损组(μmol/L:13.87±2.03<15.99±2.32<18.85±1.97),3组比较差异均有统计学意义(均P<0.05).观察组入院和出院时BHI与Hcy均呈明显负相关(入院时:左侧MCA的HBI为r=-0.512,P=0.000,右侧MCA的HBI为r=-0.498,P=0.000;出院时:左侧MCA的HBI为r=-0.426,P=0.000,右侧MCA的HBI为r=-0.431,P=0.000).结论 HBI与CI的发生发展有一定相关性,可作为CI发生发展和病情程度判断的指标.

关键词：屏气指数脑梗死相关性