Investigation into Impedance Measurements for Rapid Capacity Estimation of Lithium-ion Batteries in Electric Vehicles

With the dramatic increase in electric vehicles(EVs)globally,the demand for lithium-ion batteries has grown dramatically,resulting in many batteries being retired in the future.Developing a rapid and robust capacity estimation method is a challenging work to recognize the battery aging level on service and provide regroup strategy of the retied batteries in secondary use.There are still limitations on the current rapid battery capacity estimation methods,such as direct current internal resistance(DCIR)and electrochemical impedance spectroscopy(EIS),in terms of efficiency and robustness.To address the challenges,this paper proposes an improved version of DCIR,named pulse impedance technique(PIT),for rapid battery capacity estimation with more robustness.First,PIT is carried out based on the transient current excitation and dynamic voltage measurement using the high sampling frequency,in which the coherence analysis is used to guide the selection of a reliable frequency band.The battery impedance can be extracted in a wide range of frequency bands compared to the traditional DCIR method,which obtains more information on the battery capacity evaluation.Second,various statistical variables are used to extract aging features,and Pearson correlation analysis is applied to determine the highly correlated features.Then a linear regression model is developed to map the relationship between extracted features and battery capacity.To validate the performance of the proposed method,the experimental system is designed to conduct comparative studies between PIT and EIS based on the two 18650 batteries connected in series.The results reveal that the proposed PIT can provide comparative indicators to EIS,which contributes higher estimation accuracy of the proposed PIT method than EIS technology with lower time and cost.

THEORY AND APPLICATION OF FIELD PERTURBATION TO ELECTRICAL IMPEDANCE TECHNIQUE FOR MEDICINE

A new approach called field perturbation theory is presented to analyze the electricalimpedance technique for medicine.The formula of constant voltage and constant current fieldperturbation,modified G-L formula and the formula of electrical field perturbation evoked bysound field are derived.The application results of the theory in electroglottography are alsointroduced.

A New Stealth Technique for Vehicles Based on the Enhancement of Angular Glint

A general 2-D problem of electromagnetic scattering from a multiple cavity-backed longitudinally loaded slotted perfectly conducting cylinder with arbitrary cross section is formulated. The formulation is used to account for the scattered field from the scale models, for which, a series of experiments has been conducted in an anechoic chamber. Quite good agreement between theory and experiment is obtained. The analysis of the experimental results near resonant frequency shows that the reduction of backscattering radar cross section over wide aspect angles, and the dominant enhancement of target angular glint (linear deviation) can be achieved by impedance loading such as multiple cavity-backed slots, which realizes a new stealth technique for vehicles.

A Novel Theory: Measuring the Real-Time-Based Arterial Properties via Vascular Loading Decoupling Technique

This paper presents a decoupling theory named as Vascular Loading Decoupling Technique (VLDT), extended from the beat-based Tissue Control Method (TCM), for noninvasive measurement of real-time-based intra-arterial blood pressure and dynamic compliance of blood vessel. Both VLDT and TCM are based upon the decoupling theory to cause the arterial pulsation without the influence from surrounding tissues and measure the variations of the vascular diameter at critical depth. Meanwhile, the AC part of blood pressure is lost, that is, the reference pressure for AC controller is absent as well. To remedy this problem, VLDT employs Step-Hold control rules and cubic spline curve fitting technique to estimate the reference pressure, identify the impedance of blood vessel, and calculate the AC control gain at Hold stage, then track the AC part of blood pressure and compute the real-time arterial blood pressure at Step stage by turns, which makes the real time measurement feasible;moreover, the dynamic compliance of blood vessel can be extracted from real-time impedances of blood vessel. Since the compliance of blood vessel is decoupled from surrounding tissues, it is valuable for diagnosing the severity of vascular sclerosis. The simulation results showed that the VLDT approach is superiority over TCM. This could provide new prospective to circulatory medicine research.

基于阶梯阻抗谐振器的双频宽带滤波功分器

为了更好地满足无线通信系统对多功能、多频段射频前端器件的要求,提出了一种基于阶梯阻抗谐振器的双频宽带滤波功率分配器。首先,使用单个T形谐振器实现双频滤波单元,同时采用阶梯阻抗技术引入了单独可调的高次模用于展宽双频功分器的高频通带带宽;其次,利用枝节加载技术实现额外谐振模式的引入,展宽了双频滤波功分器低频通带带宽;为了实现小型化设计,对部分微带线进行弯折,使得整个电路结构更加紧凑。此外,利用T形谐振器自身的滤波特性和在微带馈线上加载的开路枝节,在带外产生四个可控的传输零点,提高了通带外选择性;通过在微带馈线上加载扇形枝节和在输出端口引入隔离电阻,有效改善了滤波功分器的带内阻抗匹配效果和隔离度。为了进一步验证,对所提出的滤波功分器进行了加工和测试。该滤波功分器的中心频率为2.83 GHz和4.87 GHz,相对带宽分别为10.6%和11.7%,通带隔离度均大于14.5 dB。测试和仿真结果基本一致。

铜合金海水管路腐蚀防护及检测技术研究现状

介绍了铜及铜合金海水管路腐蚀的研究进展,并指出铜合金海水管路的腐蚀特征,进而分析适用于海水管路的腐蚀防护技术,并介绍海水管路腐蚀检测与评估的方法,为海水管路的腐蚀防护提供参考。

基于压电筒状叠堆的无线金属腐蚀探针设计及性能研究

基于压电筒状叠堆和压电阻抗技术提出了一种由压电筒状叠堆和金属杆组成的新型金属腐蚀探针。建立了多层结构探针纵向振动的传递矩阵模型,导出了电学阻抗方程,求得了第一阶谐振频率和反谐振频率,并与已有文献的特例结果进行了对比,验证了理论求解的正确性。此外,采用理论分析、人造定量腐蚀试验、温度敏感试验、加速腐蚀试验和无线阻抗测试试验系统地研究了探针的性能。研究结果表明:探针的第一阶谐振频率和反谐振频率随着杆长减小而增大,随着腐蚀天数的增加而增大,随着温度的增大而减小;无线阻抗系统测量的阻抗谱与传统阻抗分析仪的测量结果一致性较好。研究成果为开发无线定量测量的新型金属腐蚀探针提供重要参考。

基于斩波稳定技术的可编程增益放大器

为满足模拟前端检测电路的低噪声、低失调的要求,介绍一种采用0.18μm CMOS工艺制作的基于斩波稳定技术的可编程增益放大器。采用斩波稳定技术降低失调与低频1/f噪声,利用可编程增益级提高模拟前端电路输出摆幅的利用率,以满足不同环境下的检测需求。该款放大器从1 Hz到10 kHz的等效输入噪声积分值为1.43μV,使用阻抗增强电路实现4.52 GΩ的运放输入阻抗;采用C-2C电容阵列作为可变电容阵列,可实现0~15倍最小步长1/64倍的增益调节,对于需要精细化调节增益的低噪声电路有广泛的应用场景。

微区扫描电化学测试技术原理及其应用进展

微区扫描电化学测试由于其独特的检测手段被广泛运用。本文综述了扫描振动电极技术(SVET)、扫描开尔文探针技术(SKP)、电化学阻抗谱技术(LEIS)、扫描电化学显微技术(SECM)四个微区扫描电化学测试技术的原理。并总结了微区扫描电化学测试技术在腐蚀、生物科学扫描、界面反应和能源方面的发现与应用。微区扫描电化学技术与传统电化学测量技术、扫描电镜技术等相结合,将有助于更深入地理解电化学行为,为材料、生物、能源等领域研究取得新突破提供技术支持。

Influence of a laser profile in impedance mismatch techniques applied to carbon EOS measurement

We present a recent numerical analysis of impedance mismatch technique applied to carbon equation of state measurements.We consider high-power laser pulses with a Gaussian temporal profile of different durations.We show that for the laser intensity(≈1014W/cm2)and the target design considered in this paper we need to have laser pulses with rise-time less than 150 ps.

基于EMI技术的减速器振动噪声分析与优化

近些年来,齿轮减速器在现代工业社会得到的广泛应用,随之产生的噪声也影响着人们的生活质量。本文以JZQ减速器为研究对象,计算其啮合频率并借助ANSYS分析减速器的固有频率,并通过压电阻抗实验验证了减速器产生振动噪声的原因。利用ANSYS中的声学分析模块通过对改变减速器壳体厚度后声压级的变化的分析,证明该方法可实现有效的降噪,为减速器噪声优化提供一种较为简单的方案。

绕组交叉换位排布方式下高频变压器阻抗建模及谐振特性分析

高频变压器设计中通常采用初、次级绕组交叉换位排布方式来降低漏电感和交流电阻,但是绕组结构改变会同时影响变压器内部寄生电容参数大小和分布情况,进而造成宽频带谐振特性发生变化。为了明确不同交叉换位排布方式对寄生电容、频变漏电感以及谐振频率的影响规律,该文首先结合绕组的排布方式和绕制方法,建立4种典型绕组结构的分布等效电容表征模型,基于能量等效原理推导出相应绕组排布方式下六集总电容表征模型的电容解析计算式。然后,为了计及宽频区间内绕组漏电感参数的频变特性,基于电磁对偶原理建立含频变参数有损电感表征模型,并给出各项参数提取方法。在此基础上,构建不同绕组布置方式下高频变压器宽频带阻抗特性分析模型。将寄生电容、漏电感参数以及开短路阻抗特性和谐振频点计算结果与仿真和实验测量结果进行对比,验证了所提方法的有效性。

基于PCA-ED的压电阻抗损伤指标提取方法

基于压电阻抗技术(EMI)进行碳纤维复合材料(CFRP)损伤实验研究,针对传统损伤指标均方根偏差(RMSD)、平均绝对偏差(MAPD)和相关系数偏差(CCD)对损伤的敏感度不高,易造成误判的问题,该文提出了一种结合主成分分析(PCA)与欧式距离(ED)的新损伤指标PCA-ED,并通过设计实验验证其对损伤的敏感性。搭建了CFRP损伤检测实验平台,设计了不同的损伤工况,测量不同损伤状态下压电换能器的电导曲线,使用PCA-ED与传统损伤指标进行损伤定量分析。实验结果表明,与传统损伤指标相比,PCA-ED指标对CFRP的损伤敏感度高。

Inner damage identification and residual strength assessment of a 3D printed tunnel with marble-like cementitious materials using piezoelectric transducers

Quantitative damage identification of surrounding rock is important to assess the current condition and residual strength of underground tunnels.In this work,an underground tunnel model with marble-like cementitious materials was first fabricated using the three-dimensional(3D)printing technique and then loaded to simulate its failure mode in the laboratory.Lead zirconate titanate piezoelectric(PZT)transducers were embedded in the surrounding rock around the tunnel in the process of 3D printing.A 3D monitoring network was formed to locate damage areas and evaluate damage extent during loading.Results show that as the load increased,main cracks firstly appeared above the tunnel roof and below the floor,and then they coalesced into the tunnel boundary.Finally,the tunnel model was broken into several parts.The resonant frequency and the peak of the conductance signature firstly shifted rightwards with loading due to the sealing of microcracks,and then shifted backwards after new cracks appeared.An overall increase in the root-mean-square deviation(RMSD)calculated from conductance signatures of all the PZT transducers was observed as the load(damage)increased.Damage-dependent equivalent stiffness parameters(ESPs)were calculated from the real and imaginary signatures of each PZT at different damage states.Satisfactory agreement between equivalent and experimental ESP values was achieved.Also,the relationship between the change of the ESP and the residual strength was obtained.The method paves the way for damage identification and residual strength estimation of other 3D printed structures in civil engineering.

MDCK-MDR1细胞药物体外吸收模型的建立及验证

目的构建MDCK-MDR1细胞体外吸收模型并进行验证,以用于口服药物吸收和转运机制的研究。方法将不同浓度组(1.0×10^(8)/L的L组、2.5×10^(8)/L的M组、5.0×10^(8)/L的H组)MDCK-MDR1细胞接种于24孔Transwell培养板上,培养1~7 d,通过吸光度值绘制MDCK-MDR1细胞生长曲线,观察不同培养时间点细胞的形态,测定不同时间点的跨膜电阻(TEER)值,确定形成单层膜结构的最佳细胞接种浓度和培养时间。通过荧光黄转运实验对不同浓度和时间点形成的单细胞膜结构进行验证。结果L组、M组和H组分别在接种后第5、3、1天形成单层膜结构,分别在第5、4、3天时吸光度值达到峰值。L组在接种第5天时TEER值达到300Ω·cm^(2),第5~7天趋于稳定,故确定形成单层膜结构的最佳细胞接种浓度为1.0×10^(8)/L,最佳培养时间为5 d。荧光黄转运实验验证显示,该单层膜结构的荧光黄表观渗透系数为4.27×10^(-7)cm/s,低于通透性试验规定的5.0×10^(-7)cm/s。结论本研究构建的MDCK-MDR1细胞模型单层膜结构完整性和通透性均通过验证,可作为模拟口服药物吸收和转运机制研究的体外模型。

小型高选择性MEMS射频滤波器的设计

该文设计了一款基于微机电系统(MEMS)工艺的小型高选择性的射频滤波器,与传统MEMS滤波器相比,该滤波器采用阶跃阻抗谐振器(SIR)降低器件尺寸,利用谐振器的场分布形成结构紧凑的交叉耦合,免去了传统的飞杆电耦合结构,在提高滤波器选择性的同时实现器件的紧凑布局。滤波器表面金属谐振腔通过金属化的硅通孔实现谐振器的接地,形成四分之一波长谐振结构。对性能和结构参数各异的滤波器进行设计和分析,并采用三维电磁仿真软件对滤波器进行模拟仿真。结果表明,滤波器尺寸为10 mm×10 mm×0.4 mm,驻波比<1.3 dB,插入损耗<3.5 dB。在2.5~2.7 GHz和3.4~3.5 GHz时,带外抑制>30 dB。

拟声波技术在受煤层影响储层预测中的应用

南图尔盖盆地萨雷兰凹陷侏罗纪发育了一套河流相灰色砂岩储层,岩性以砂、泥互层夹薄煤层为主,横向连续性差。GR曲线难以从砂、泥岩中识别煤层,而砂、泥岩阻抗叠置导致储层敏感性降低,常规波阻抗反演技术无法满足砂体展布特征的精细描述需求。基于拟声波技术,利用对砂、泥岩敏感的自然伽马曲线与声波曲线进行分频融合,同时保留对煤层敏感的原始声波曲线信息,生成具有声波量纲、能够去除煤层影响同时又能反映储层特征的拟声波曲线,在此基础上开展波阻抗反演。结果显示:反演结果与实钻井高度吻合,基于拟声波技术的地震反演能很好地消除煤层影响并有效刻画该段储层的空间展布特征。

压电阻抗实时监测技术在推进系统中的应用研究

为准确判定推进系统粘接层的“半固化状态”,保证其粘接性能,提高粘接质量,采用压电阻抗技术实时监测粘接层固化反应过程。该文构建一维粘弹性阻抗模型,设计粘接层固化过程阻抗实时监测系统,利用共振频率处的阻抗实部峰值表征粘接层固化状态。监测结果表明,随着粘接层固化反应的进行,阻抗实部峰值逐渐减小,直至粘接层完全固化后,阻抗实部峰值保持平稳,反映粘接层固化状态的变化,阻抗实部峰值的下降率能够作为判定粘接层“半固化状态”的重要指标。

甘肃及西藏藏族成人体成分分析

目的收集我国藏族居民体成分数据并比较甘肃、西藏藏族成人体成分各指标差异，揭示藏族成人体成分分布的特点。方法采用整群抽样法抽取西藏藏族自治区日喀则市，甘肃省甘南藏族自治州、天祝藏族自治县藏族成年居民共814名，采用生物电阻抗法检测受试者体成分各项指标，比较两省区藏族成年人体成分数据的差异。结果藏族成年男性身体质量指数（BMI）、去脂体重、体脂肪率、内脏脂肪量、皮下脂肪量、肌肉量、身体水分及蛋白质量、腰臀比（WHR）均在40～50岁达到峰值，基础代谢在40～50岁后随着年龄的增长下降，细胞内外液比值（E／I）随年龄的增长而升高；女性去脂体重、肌肉量、基础代谢在30～40岁达到高峰，身体水分量在40～50岁达到最大值；BMI、体脂肪率、内脏脂肪量、皮下脂肪量、WHR及E／I均随年龄的增高而升高，而蛋白质量随年龄增高而下降。甘肃藏族BMI、去脂体重、肌肉量、皮下脂肪量、内脏脂肪量、身体水分、基础代谢、超重肥胖比率均高于西藏藏族，西藏藏族成人WHR过高的比率高于甘肃藏族，差异有统计学意义（P〈0．05）。结论我国藏族成人男性及女性体成分中脂肪相关指标随年龄增长分别呈正弦曲线及单向增高变化；不同地域藏族成人体成分也存在差异，甘肃藏族成人体成分多项指标尤其是大部分体脂肪相关指标高于西藏藏族成人，可能会导致甘肃藏族成人慢性病发病率较高。