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991.
二元稀土系AB5型贮氢电极合金的放电容量与晶胞体积和4f电子浓度的关系 总被引:3,自引:0,他引:3
制备了6个系列通式为AαA‘1-αB5的RE(NiCoMnTi)5贮氢电极合金(其中,AαA‘1-α为La,Ce,Pr,Nd4个元素中任意2个的组合),测定了它们在100次循环中的最大放电容量Cmax及部分合金的晶胞体积Vcell.结果表明:Cmax主要由Vcell决定,Cmax先随Vcell的增大而增加,在Vcell≈85.66x10^-^3。nm^3时达到一极大值,然后又随Vcell的增大而减小;同时,Cmax还与4f电子浓度ne4f/naRE有关,A侧具有相同4f电子浓度的合金其Cmax随4f电子浓度的变化趋势相似. 相似文献
992.
连铸中间包内三维湍流流动的数值模拟 总被引:11,自引:0,他引:11
连铸中间包的操作条件决定了其内流动现象的复杂性,为此,本文选择两种不同的湍流模型k-ε和LES(Largeeddysimulation),建立了描述连铸中间包内三维湍流流动的数学模型,并实施了数值计算和模型验证,对单流中间包内的流动现象进行了描述,考察了有,无流动控制情况下中间包内的流动特征和湍流模型的合理性,结果表明,合理的流动控制有利于中间包内非金属夹杂的上浮和吸附,用k-ε模型基本上能够描述 相似文献
993.
稀土元素对硬质合金高温性能的影响 总被引:2,自引:0,他引:2
采用动态热模拟试验技术,研究了添加微量稀土元素对硬质含金高温性能的影响。试验结果表明:添加微量稀土元素,能改善硬质合金高温性能,增加合金的塑性和高温韧性,降低硬质合金的热强性。 相似文献
994.
方柱体镦粗的两个新力学模型 总被引:8,自引:1,他引:8
在对平板间镦粗圆柱体的研究[1,2,3]基础上,进一步对普通平板间的方柱体镦粗,进行了工程力学的分析,提出了二个新力学模型,并进行了实验验证。这为形成新的拔长理论[4,6]奠定了力学基础。 相似文献
995.
应用人工神经网络理论建立热粘塑性材料的本构关系 总被引:2,自引:1,他引:2
本文将人工神经网络(ANN)用于建立热粘塑性材料的本构关系,意在探索出一种描述材料变形力学行为的新方法。文中给出了应用人工神经网络建立热粘塑性材料本构关系的BP模型和学习算法过程,并应用于45号钢在高温和高速变形条件下的流动应力计算。计算结果与实测结果比较表明,二者吻合良好。因此,应用人工神经网络建立热粘塑性材料的本构关系具有重要的工程应用价值。 相似文献
996.
Marta Teixeira Pinto Ana Sofia Ribeiro Inês Conde Rita Carvalho Joana Paredes 《International journal of molecular sciences》2021,22(1)
The high plasticity of cancer stem-like cells (CSCs) allows them to differentiate and proliferate, specifically when xenotransplanted subcutaneously into immunocompromised mice. CSCs are highly tumorigenic, even when inoculated in small numbers. Thus, in vivo limiting dilution assays (LDA) in mice are the current gold standard method to evaluate CSC enrichment and activity. The chick embryo chorioallantoic membrane (CAM) is a low cost, naturally immune-incompetent and reproducible model widely used to evaluate the spontaneous growth of human tumor cells. Here, we established a CAM-LDA assay able to rapidly reproduce tumor specificities—in particular, the ability of the small population of CSCs to form tumors. We used a panel of organotropic metastatic breast cancer cells, which show an enrichment in a stem cell gene signature, enhanced CD44+/CD24−/low cell surface expression and increased mammosphere-forming efficiency (MFE). The size of CAM-xenografted tumors correlate with the number of inoculated cancer cells, following mice xenograft growth pattern. CAM and mice tumors are histologically comparable, displaying both breast CSC markers CD44 and CD49f. Therefore, we propose a new tool for studying CSC prevalence and function—the chick CAM-LDA—a model with easy handling, accessibility, rapid growth and the absence of ethical and regulatory constraints. 相似文献
997.
Equivalent model of multi-type distributed generators under faults with fast-iterative calculation method based on improved PSO algorithm 下载免费PDF全文
Puyu Wang Jinyuan Song Fangyu Liang Fang Shi Xiangping Kong Guangen Xie Xiao-Ping Zhang Xinxin Gu 《电力系统保护与控制》2021,6(3):371-382
There are various types of distributed generators (DGs) with diferent grid integration strategies. The transient char?
acteristics of the fault currents provided by the DGs are diferent to those of conventional synchronous generators. In
this paper, a distribution network with multi-type DGs is investigated, including consideration of DG low-voltage ride
through (LVRT). The fault current characteristics of two typical DGs, i.e. an inverter-interfaced distributed generator
(IIDG) and a doubly-fed induction generator (DFIG), are analyzed, considering the specifc operation modes. Based on
analysis of the fault characteristics, an equivalent model of the multi-type DGs under symmetrical/asymmetrical fault
conditions is established. A fast-iterative fault calculation method for enhancing the calculation efciency while avoid?
ing local convergence is then proposed using an improved particle swarm optimization (PSO) algorithm. A simula?
tion system of the distribution network with multi-type DGs is established in PSCAD/EMTDC. The simulation results
validate the high accuracy and calculation efciency of the proposed calculation method of the fault components.
This can assist in the settings of the protection threshold. 相似文献
998.
Nadine Reichhart Vladimir M. Milenkovic Christian H. Wetzel Olaf Strauß 《International journal of molecular sciences》2021,22(5)
The anoctamin (TMEM16) family of transmembrane protein consists of ten members in vertebrates, which act as Ca2+-dependent ion channels and/or Ca2+-dependent scramblases. ANO4 which is primarily expressed in the CNS and certain endocrine glands, has been associated with various neuronal disorders. Therefore, we focused our study on prioritizing missense mutations that are assumed to alter the structure and stability of ANO4 protein. We employed a wide array of evolution and structure based in silico prediction methods to identify potentially deleterious missense mutations in the ANO4 gene. Identified pathogenic mutations were then mapped to the modeled human ANO4 structure and the effects of missense mutations were studied on the atomic level using molecular dynamics simulations. Our data show that the G80A and A500T mutations significantly alter the stability of the mutant proteins, thus providing new perspective on the role of missense mutations in ANO4 gene. Results obtained in this study may help to identify disease associated mutations which affect ANO4 protein structure and function and might facilitate future functional characterization of ANO4. 相似文献
999.
Dora Szabo Zsolt Sarszegi Beata Polgar Eva Saghy Adam Nemeth Dora Reglodi Andras Makkos Aniko Gorbe Zsuzsanna Helyes Peter Ferdinandy Robert Herczeg Attila Gyenesei Attila Cziraki Andrea Tamas 《International journal of molecular sciences》2021,22(6)
Acute myocardial infarction (MI) is one of the most common causes of death worldwide. Pituitary adenylate cyclase activating polypeptide (PACAP) is a cardioprotective neuropeptide expressing its receptors in the cardiovascular system. The aim of our study was to examine tissue PACAP-38 in a translational porcine MI model and plasma PACAP-38 levels in patients with ST-segment elevation myocardial infarction (STEMI). Significantly lower PACAP-38 levels were detected in the non-ischemic region of the left ventricle (LV) in MI heart compared to the ischemic region of MI-LV and also to the Sham-operated LV in porcine MI model. In STEMI patients, plasma PACAP-38 level was significantly higher before percutaneous coronary intervention (PCI) compared to controls, and decreased after PCI. Significant negative correlation was found between plasma PACAP-38 and troponin levels. Furthermore, a significant effect was revealed between plasma PACAP-38, hypertension and HbA1c levels. This was the first study showing significant changes in cardiac tissue PACAP levels in a porcine MI model and plasma PACAP levels in STEMI patients. These results suggest that PACAP, due to its cardioprotective effects, may play a regulatory role in MI and could be a potential biomarker or drug target in MI. 相似文献
1000.
目前水槽实验一般采用压电式压力传感器测量泥石流冲击力,这种传统测量模式的电信号易受电线阻抗效应的影响,且没有考虑测量装置受冲击变形对测量结果所产生的影响。针对以上问题,基于光纤布拉格光栅(Fiber Bragg Grating,FBG)传感技术,设计了悬臂梁式泥石流冲击力测量系统; 基于泥石流的宾汉体模型和受冲击体的本构关系,构建了包含中心波长最大偏移量、结构材料弹性模量和流深的泥石流最大冲击力反演公式。依据测量系统的力-光耦合效应设计水槽实验,开展了7组不同密度(1.8、1.9、2.0 g·cm-3)的冲击实验工况。结果表明:①数据之间呈现较好的规律性,光纤布拉格光栅中心波长最大偏移量随着密度的增加而增大,同一密度下光纤布拉格光栅中心波长变化过程与泥石流冲击过程相吻合,从而验证了冲击力反演模型和测量系统之间具有良好的适应性; ②冲击力峰值为30.75~74.06 kPa,冲击力系数为0.92~1.95,与泥石流冲击特性相吻合,进而验证了本测量系统在克服传统压电式压力传感器自身缺陷的同时,亦能实现冲击力的稳定可靠测量。 相似文献