基于蛙跳模糊算法的Jiles Atherton铁心磁滞模型参数确定

Jiles Atherton(JA)模型广泛应用于铁心磁滞建模领域,其参数确定精确与否直接影响铁心磁滞现象的表达,为此提出蛙跳模糊算法对JA模型参数进行辨识。为了防止蛙跳算法陷入局部最优解并加快收敛速度,根据特殊点(矫顽力、矫顽力点磁化率)处实测值与计算值的相对误差,采用模糊控制方法,得到动态反馈系数,修正蛙跳算法的步长调整公式。采用爱泼斯坦方圈搭建磁滞回线测量系统,测得铁心饱和磁滞回线与局部磁滞回线。采用蛙跳模糊算法、蛙跳算法、粒子群算法和遗传算法分别求解得到模型参数,并将计算的磁滞回线与实测磁滞回线进行比较,证明了所提出的蛙跳模糊算法不易陷入局部最优解且具有更快的收敛速度。根据蛙跳模糊算法得到的局部磁滞回线模型参数辨识结果,研究模型参数与磁通密度的关系并进行拟合,得到不同磁通密度下的局部磁滞回线参数拟合模型。     

浅谈小电流接地系统的单相接地故障检测方法

本文浅谈高压电力网小电流接地，系统单相接地故障的检测方法，并就其故障带来的影响和危害，以及各种方法的工作原理、选线基准、特点等作了简单的分析。     

粉末压片-X射线荧光光谱法测定深海富铁粘土中主次量组分

富铁粘土赋存于深海大洋的某些区域,目前缺乏富铁粘土相关标准物质和分析方法,实验利用台式X射线荧光光谱仪(XRF)结合压片法制样现场快速测定深海富铁粘土样品中的Na₂O、MgO、Al₂O₃、SiO₂、P₂O₅、K₂O、CaO、TiO₂、Mn、Fe、Cu、Zn、V、Sr、Zr、Ba、Pb和Y等组分。优化选择压力30 t和保压35 s的制样条件;采用多金属结核和富钴结壳、深海及近海沉积物国家标准物质以及定值深海富铁粘土样品绘制校准曲线, 解决了缺少富铁粘土标准物质的问题。对18个组分的测量条件进行了优化,使用经验系数法校正了主要成分SiO₂、CaO、Fe和Mn的基体效应。方法的检出限为3.67~1172μg/g。精密度试验结果表明,各组分测定值的相对标准偏差(RSD,n=7)在0.3%~2.2%之间。方法用于实际样品的分析,其分析结果与实验室采用其他方法的测定结果吻合,能够满足野外现场富铁粘土样品中多种组分同时快速分析的要求。     

一种新型的电磁裂解装置用于制备大豆小分子多肽

大豆小分子多肽是大豆蛋白水解物,但与大豆蛋白相比,大豆多肽往往具有更良好的理化性质和生理活性。目前,国内外生产大豆多肽的主要方法是通过酶法转化或微生物发酵,为获得一种制备大豆小分子多肽简易且环保的方法,文章研究一种新型的装置用于大豆小分子多肽的制备,其基本原理是将变频变压正弦交流电作用于水浸泡的大豆,不添加任何化学试剂,通过物理方法水解大豆蛋白制备大豆小分子多肽,结果表明,电磁裂解时间在60 min左右制备的大豆小分子多肽含量较高。由此得出结论,电磁裂解法在制备大豆小分子多肽方面有很大的优势,且效果因电磁裂解时间的不同而有所差异。电磁裂解时间约为60 min时,大豆小分子多肽的含量最高。     

A preliminary study on platelet aggregation in postmenopausal women consuming extra-virgin olive oil and high-oleic acid sunflower oil

The purpose of the present study was to examine the effects of two monounsaturated fatty acid-rich oils, extravirgin olive oil (EVOO) and high-oleic sunflower oil (HOSO), on platelet aggregation in 14 postmenopausal women (aged 62.9 ± 1.8 yr) with high-fat dietary habits. Both oils contained oleic acid as the major compound (≈76% of total fatty acids), but the content of palmitic and linoleic acids and many minor compounds was significantly different. These oils were used as the only culinary fats during two 28-d periods, and represented ≈62% of the total lipid intake (≈46% of total energy consumption). Other dietary components were matched. The daily energy contribution of saturated, monounsaturated, and polyunsaturated fatty acids to the total energy consumption was 11.8, 28.5, and 2.8%, respectively, during the EVOO dietary period and 10.3, 27.8, and 4.6%, respectively, with HOSO. Aggregation in platelet-rich plasma was measured after addition of ADP. Platelet aggregation (expressed as cm/5 min) was significantly lower after the EVOO diet than after HOSO (2.1 ± 1.1 and 3.0 ± 1.4, respectively; P<0.05). Although maximal aggregation time was 40.2% higher in HOSO than in EVOO, the difference was not significant. Independent of serum cholesterol level, platelet aggregation tended to be different on the EVOO diet when women were classified according to cholesterol levels: <220 mg/dL or ≥220 mg/dL. Results suggest that other compounds present in the oils aside from the fatty acids may play an important role in modulating platelet aggregation in these postmenopausal women.     

熔融制样-X射线荧光光谱法测定钨铁合金中硅锰磷铜钨

钨铁合金是冶炼高速钢等钨合金钢的加入剂,目前采用化学湿法分析钨、硅、锰、磷和铜的含量,实验流程很长,操作相对繁琐。实验采用碳酸锂和过氧化钠作氧化剂预氧化样品、熔融方法制样,建立了X射线荧光光谱法(XRF)测定钨铁合金中硅、锰、磷、铜、钨5 种元素含量的检测方法。绘制校准曲线时,采用钨铁标准样品中加入三氧化钨纯物质及硅、锰、磷、铜标准溶液的方法扩展了校准曲线线性范围。实验表明,以四硼酸锂为熔剂,溴化铵为脱模剂,试样与熔剂比例为1∶30,在1150℃熔融炉中熔融10min,制得表面光滑、无气孔、无结晶的均匀玻璃片。实验方法用于测定钨铁合金样品中硅、锰、磷、铜、钨,测定结果的相对标准偏差(RSD,n=8)为0.20%~5.2%;按照实验方法测定3个钨铁合金样品中硅、锰、磷、铜、钨,并与相应的国家标准方法进行比对,结果相一致。     

熔融制样-X射线荧光光谱法测定酸溶性钛渣中主次量成分

酸溶性钛渣是优质的钛白生产原料,产品中的主次成分含量直接影响到后续钛白产品质量。针对酸溶性钛渣中含有低价物的特点,试验了粉末压片法制备样品的X射线荧光光谱法分析效果,并建立了熔融玻璃片制备方法:采用Li₂B₄O₇和Li₂CO₃作为熔剂,NH₄NO₃作为氧化剂,在石墨垫底瓷坩埚中先将酸溶性钛渣预氧化,再将熔球转入铂黄金坩埚,解决了样品中低价物对铂黄金坩埚腐蚀的难题。实验采用理论α影响系数法进行基体效应和谱线重叠干扰校正,进而通过对熔融条件及各待测元素测量条件的优化,以及采用金红石、钛渣、钛精矿等标准样品及人工合成校准样品绘制校准曲线,建立了X射线荧光光谱法(XRF)同时测定酸溶性钛渣中TiO₂、SiO₂、Al₂O₃、MnO、CaO、MgO、TFe、V₂O₅、ZrO₂等主次量成分的方法。将实验方法应用于酸溶性钛渣实际样品分析,所测组分测定结果的相对标准偏差(RSD,n=11)均小于1.5%。采用实验方法测定酸溶性钛渣中主次量成分,分析结果与化学湿法结果吻合。     

Actinide and lanthanide dioxide lattice dilatation mechanisms with defect ingrowths

The effects of irradiation-induced defects on the fluorite-structured dioxide materials were investigated in the literature and explained with complex physical phenomena. An interpretation that can simply explain their effects on the structure has not been put forward so far. However, in a recent atomistic simulation study, a specific defect was found to be directly responsible for the α-particle irradiated UO₂ lattice dilatation, and there was a linear relationship between them. It was also determined that this linear equation has two different slopes at low and high defect concentrations. In this paper, it was found that these phenomenon were not specific to UO₂ and applicable to all fluorite-structured actinide and lanthanide dioxides studied here (CmO₂, AmO₂, CeO₂, UO₂, NpO₂, PuO₂, ThO₂). The findings provide clues to the existence of more general law. The results have the potential to lead to significant improvements, such as why different radiation types (α-particle, α-decay, fission) swell the lattice at different saturation levels.     

功能离子液体在镧锕系离子萃取分离中的研究进展北大核心CSCD

离子液体因其独特的物化性质已成为溶剂萃取领域中绿色环保、极具应用前景的稀释剂。除了对萃取剂和萃合物有良好溶解性之外,离子液体萃取体系通过离子交换机理的协同作用,往往还展现出更优的萃取性能。而功能离子液体通常是在离子液体结构基础上进行化学修饰,使其兼具离子液体和螯合基团的双重功能,在萃取过程中不仅能用作稀释剂,还具有萃取作用。近十余年来,功能离子液体在放化分离领域已引起广泛关注。本文首先对离子液体和功能离子液体进行了简介,重点讨论其结构上的关联与区别;再以功能为导向,综述了功能离子液体在铀酰离子、钍离子、镧系和次锕系金属离子萃取分离方面的国内外研究现状,并对功能离子液体在镧锕萃取分离领域的未来研究趋势进行了展望。     

Risk-sensitive large-population linear-quadratic-Gaussian Games with major and minor agents

This paper studies large-population dynamic games involving a linear-quadratic-Gaussian (LQG) system with an exponential cost functional. The parameter in the cost functional can describe an investor's risk attitude. In the game, there are a major agent and a population of $N$ minor agents where $N$ is very large. The agents in the games are coupled via both their individual stochastic dynamics and their individual cost functions. The mean field methodology yields a set of decentralized controls, which are shown to be an $ϵ$-Nash equilibrium for a finite $N$ population system where $ϵ=O\left(\frac{1}{\sqrt{N}}\right)$. Numerical results are established to illustrate the impact of the population's collective behaviors and the consistency of the mean field estimation.