基于电化学与热能的耦合关系演算聚合物锂离子动力电池的温度状态及分布

基于电化学-热耦合模型研究聚合物锂离子动力电池放电过程热行为, 分析了放电倍率、冷却条件对电池放电过程的温度变化及分布的影响规律. 结果表明: 3C放电时, 模型计算结果与实测结果的平均偏差为0.57 K, 方差为0.15, 说明模型准确度较高. 电芯的平均生热率在整个放电过程中呈现出增加的趋势, 初期和末期增长较快. 大倍率放电时, 与电流密度的平方呈正比的不可逆热所占的比重较大, 小倍率放电时, 电化学反应可逆热占主导. 改善冷却条件能降低电池放电过程的平均温度, 对流传热过程的表面传热系数为5 W/(m²·K), 1 C, 3 C, 5 C放电结束时, 电芯的平均温升为分别为6.46 K, 17.67 K, 27.53 K, 当对流传热过程的表面传热系数增加至25 W/(m²·K)时, 温升比自然对流条件下相同倍率放电时的温度分别降低了2.91 K, 4.68 K, 5.62 K, 但电芯温度分布的不一致性也会加剧. 关键词： 电化学 耦合 锂离子动力电池 温度分布     

国产六面顶压机多晶种法合成宝石级金刚石单晶

对国产六面顶压机平台下使用多晶种法合成宝石级金刚石单晶进行了系统的研究. 通过合理调整温度梯度法的合成腔体组装, 采用多晶种法, 探索多晶种法金刚石合成的压力和温度区间, 在单个合成腔体内放置3–5颗金刚石晶种, 成功合成出多颗(3–5)优质Ib型宝石级金刚石单晶. 多颗晶种的引入, 单次实验合成的多个金刚石晶体晶形及品质一致; 同时, 晶体的整体生长速度也有明显的增大. 多晶种法金刚石单晶合成的研究, 可以有效地利用腔体空间、提高单次金刚石单晶合成的效率, 解决压机大型化下高温高压资源利用率低的问题; 同时, 为宝石级金刚石单晶商业化生产提供重要的依据. 关键词： 金刚石 国产六面顶 多晶种 温度梯度法     

Ga1-xInxNyAs1-y/GaAs量子阱中电子-LO声子的散射率

在有效质量近似下利用打靶法求出Ga_1-xIn_xN_yAs_1-y/GaAs量子阱中的本征能级E_n, 并通过费米黄金规则计算电子-LO声子由第一激发态到基态的散射率和平均散射率随温度、阱宽以及氮(N)和铟(In)组分变化的规律. 计算结果表明: 在In 组分恒定的情况下, 随着N组分的增加, 散射率和平均散射率增加; 在N组分恒定的情况下, 随着In组分的增加, 散射率和平均散射率减小; 随着温度的增加, 在温度较低时散射率和平均散射率随温度的增加变化不大, 在温度较高时随温度的增加而增加; 随着阱宽的增加, 散射率和平均散射率都是先增加到一个最大值, 然后再减小, 最大值出现在阱宽200 Å附近. 计算结果对Ga_1-xIn_xN_yAs_1-y/GaAs量子阱在光电子器件应用方面有一定的指导意义. 关键词： 费米黄金规则 1-xIn_xN_yAs_1-y/GaAs量子阱')" href="#">Ga_1-xIn_xN_yAs_1-y/GaAs量子阱 LO声子 散射率     

电场诱导氧化石墨烯的极化动力学特性研究

本文通过外加电场改变氧化石墨烯团簇分子的共振能量,利用激光激发氧化石墨烯产生的共振荧光特性测量氧化石墨烯在电场作用下的极化动力学特性. 发现存在外加电场使得荧光共振峰的半高全宽趋于饱和的时间特性,而不同的氧化石墨烯团簇分子的荧光共振峰的暂态特性同时反映了电场对氧化石墨烯产生定向极化和变形极化的动力学特性. 关键词： 氧化石墨烯 团簇分子 电场 极化动力学     

A modular attachment mechanism for software network evolution

A modular attachment mechanism of software network evolution is presented in this paper. Compared with the previous models, our treatment of object-oriented software system as a network of modularity is inherently more realistic. To acquire incoming and outgoing links in directed networks when new nodes attach to the existing network, a new definition of asymmetric probabilities is given. Based on this, modular attachment instead of single node attachment in the previous models is then adopted. The proposed mechanism is demonstrated to be able to generate networks with features of power-law, small-world, and modularity, which represents more realistic properties of actual software networks. This work therefore contributes to a more accurate understanding of the evolutionary mechanism of software systems. What is more, explorations of the effects of various software development principles on the structure of software systems have been carried out, which are expected to be beneficial to the software engineering practices.     

Using Gd-EOB-DTPA-enhanced 3-T MRI for the differentiation of infiltrative hepatocellular carcinoma and focal confluent fibrosis in liver cirrhosis

Purpose

The purpose of the study was to determine significant imaging features to differentiate between infiltrative hepatocellular carcinoma (HCC) and confluent fibrosis (CF) in liver cirrhosis using Gd-EOB-DTPA-enhanced 3-T magnetic resonance imaging.

Material and methods

Nineteen infiltrative HCCs and eight CFs were included. We evaluated the difference in imaging findings and apparent diffusion coefficient (ADC) between the two entities. We compared T2-weighted image (WI) and hepatobiliary phase (HBP) in terms of the clarity of the lesion outer margin.

Results

Seventeen infiltrative HCCs showed lobulated margin, while focal CFs showed either straight (n = 3) or irregular margins (n = 5) (P = .001). All infiltrative HCCs had intact or bulging contours, and all focal CFs showed capsular retraction (P = .001). Fourteen infiltrative HCCs and two focal CFs showed arterial enhancement (P = .035). The ADC of infiltrative HCCs was significantly lower than that of CFs (P = .001). Satellite nodules were noted in 10 infiltrative HCCs. In terms of outer margin clarity, infiltrative HCCs showed a more distinct margin on HBP than on T2-WI (P = .005), while these two sequences were not significantly different in focal CFs (P = 1.000).

Conclusion

HBP improved the imaging characteristics of infiltrative HCC, allowing it to be distinguished from focal CF. Infiltrative HCC showed lower ADC values than focal CF. Lobular configuration, contour bulging, enhancement pattern, associated satellite nodules and portal vein thrombosis were still found to be highly suggestive MR findings for infiltrative HCC.     

Investigation of odd-order nonlinear susceptibilities in atomic vapors

We theoretically deduce the macroscopic symmetry constraints for arbitrary odd-order nonlinear susceptibilities in homogeneous media including atomic vapors for the first time. After theoretically calculating the expressions using a semiclassical method, we demonstrate that the expressions for third- and fifth-order nonlinear susceptibilities for undressed and dressed four- and six-wave mixing (FWM and SWM) in atomic vapors satisfy the macroscopic symmetry constraints. We experimentally demonstrate consistence between the macroscopic symmetry constraints and the semiclassical expressions for atomic vapors by observing polarization control of FWM and SWM processes. The experimental results are in reasonable agreement with our theoretical calculations.     

TiO2 Nanotube Array/Monolayer Graphene Film Schottky Junction Ultraviolet Light Photodetectors

Schottky junctions made from a titanium dioxide nanotube (TiO₂NT) array in contact with a monolayer graphene (MLG) film are fabricated and utilized for UV light detection. The TiO₂NT array is synthesized by the anodization and the MLG through a simple chemical vapor deposition process. Photoconductive analysis shows that the fabricated Schottky junction photodetector (PD) is sensitive to UV light illumination with good stability and reproducibility. The corresponding responsivity (R), photoconductive gain (G), and detectivity (D*) are calculated to be 15 A W^?1, 51, and 1.5 × 10¹² cm Hz^1/2 W^?1, respectively. It is observed that the fabricated PD exhibits spectral sensitivity and a simple power‐law dependence on light intensity. Moreover, the height of the Schottky junction diode is derived to be 0.59 V by using a low temperature I–V measurement. Finally, the working mechanism of the TiO₂NT array/MLG film Schottky junction PD is elucidated.     

Synthesis,Characterization, and Antibacterial Activity of RE(III) Complexes with L-Isoleucine and 1,10-Phenanthroline

Six new ternary rare-earth (La, Eu, Sm, Nd, Y, Yb) complexes with L-isoleucine and 1,10-phenanthroline have been synthesized. Their compositions were characterized as RE(Ile)₃PhenCl₃ · 4H₂O (RE = La, Eu, Sm, Nd, Y, Yb; Ile = L-isoleucine; phen = 1,10-phenanthroline) by elemental analysis, EDTA titration, molar conductance measurement, UV spectra, FT-IR spectra, and TG-DTA. The average diameters of growth inhibition area and the minimal inhibitory concentration (MIC) of the complexes were studied by disc diffusion method and dilution method in nutrient broth. The results showed that the ternary rare-earth complexes strongly exhibited the antibacterial activity against Escherichia coli and Staphylococcus aureus and that their antibacterial effects were better than those of rare-earth chlorides, L-isoleucine, and 1,10-phenanthroline.     

Crystalline Morphology and Nonisothermal Crystallization Behaviors of iPP/PcBR Blends

Isotactic polypropylene/poly(cis‐butadiene) rubber (iPP/PcBR) blends were prepared by melt mixing. The influence of PcBR content on crystalline morphology and nonisothermal crystallization behaviors of iPP was investigated by polarized optical microscopy (POM), small angle light scattering (SALS), and differential scanning calorimetry (DSC). The POM showed that an increase of PcBR ranging from 10 vol% to 40 vol% led to less perfection of spherulites, vaguer boundaries between spherulites, and smaller spherulite size, which was quantitatively validated by SALS. The presence of PcBR also remarkably affected the nonisothermal crystallization behaviors of iPP. An addition of PcBR caused higher crystallization peak temperature and a faster crystallization rate, meaning a heterogeneous nucleation effect of PcBR upon crystallization of iPP. For the same sample, the crystallization peak temperature moved to lower temperature and the crystallization rate increased as the cooling rate increased. The Ozawa and combined Avrami and Ozawa equations were used to describe the nonisothermal crystallization process of iPP and blends. The combined Avrami and Ozawa equation was more appropriate for the crystallization of the blends. Crystallization activation energy of iPP and blends was calculated by the Kissinger equation; the result showed that crystallization activation energy decreased as the content of PcBR increased from 30 vol% to 40 vol%.