基于DE-ELM的电池SOC预测研究

针对极限学习机的随机性较大的问题,提出一种基于差分演化的极限学习机算法模型(DE-ELM).采用差分演化算法(DE)对极限学习机(ELM)随机给定的输入权值矩阵和隐含层阈值进行寻优,降低了随机性给ELM造成的影响,减少ELM网络震荡,提高了ELM预测精度.并且将DE-ELM应用在电池SOC的预测上,同时与ELM和BP神经网络的预测进行了对比,结果表明:DE-ELM在电池SOC预测上的表现优于ELM和BP神经网络,能满足电池SOC的预测精度要求.     

Characteristics and properties of metal aluminum thin film prepared by electron cyclotron resonance plasma-assisted atomic layer deposition technology

Metal aluminum (Al) thin films are prepared by 2450-MHz electron cyclotron resonance plasma-assisted atomic layer deposition on glass and p-Si substrates using trimethylaluminum as the precursor and hydrogen as the reductive gas. We focus our attention on the plasma source for thin-film preparation and annealing of as-deposited films related to the surface square resistivity. The square resistivity of as-deposited Al film is greatly reduced after annealing and almost reaches the value of bulk metal. Through chemical and structure analysis we conclude that the square resistivity is determined by neither contaminant concentration nor surface morphology, but by both crystallinity and crystal size in this process.     

具有Dzyaloshinskii-Moriya相互作用的XY模型的量子相干性

研究了具有Dzyaloshinskii-Moriya(DM)相互作用的一维横场XY自旋链的量子相变和量子相干性.采用约旦-维格纳变换严格求解了哈密顿量,并描绘了体系的关联函数和相图,相图包含反铁磁相、顺磁相和螺旋相.利用相对熵和Jensen-Shannon熵讨论了XY模型的量子相干性.研究发现,相对熵与Jensen-Shannon熵所表现的行为都可以很好地表征该模型的量子相变.非螺旋相中量子相干性不依赖DM相互作用,而在螺旋相DM相互作用对量子相干性有显著影响.此外,指出了在带有DM相互作用的这一类反射对称破缺体系中关联函数计算的常见问题.     

Using a quantum dot system to realize perfect state transfer

There are some disadvantages to Nikolopoulos et al.'s protocol [Nikolopoulos G M, Petrosyan D and Lambropoulos P 2004 Europhys. Lett. 65 297] where a quantum dot system is used to realize quantum communication. To overcome these disadvantages, we propose a protocol that uses a quantum dot array to construct a four-qubit spin chain to realize perfect quantum state transfer (PQST). First, we calculate the interaction relation for PQST in the spin chain. Second, we review the interaction between the quantum dots in the Heitler-London approach. Third, we present a detailed program for designing the proper parameters of a quantum dot array to realize PQST.     

基于多光谱遥感数据的生物多样性监测与评估

生物多样性是人类赖以生存的基础。受环境和气候变化的影响,全球生物多样性丧失日趋严重,研究区域生物多样性对保护濒危物种栖息地、合理规划与利用区域资源具有重要意义。基于2002年—2018年多光谱遥感植被产品中的NDVI、 EVI、 FPAR、 LAI、 GPP数据集,构建了累积、最小和差值三种动态生境指数(DHI),结合气象数据和物种分布数据,采用多元回归分析分别研究了(1)基于NDVI、 EVI、 FPAR、 LAI、 GPP多光谱遥感指数构建的DHIs评价生物多样性的适用性;(2)累积、最小和差值DHIs表达物种多样性的互补性;(3)气候变化对我国生物多样性的影响;(4)累积、最小和差值DHIs表达物种丰富度的能力。研究表明：(1)基于同种MODIS多光谱植被指数的同一DHIs之间具有很强的相关性(相关系数0.77到0.98之间),可相互替代;同一植被指数的累积、最小和差值DHIs之间有一定关联性,但三者不可相互替代。(2)与基于NDVI、 EVI、 FPAR、 LAI产品数据构建的DHIs相比,GPP-DHIs监测我国生物多样性的能力最强,且与物种丰富度之间存在良好的相关性(相关系...     

Modulation of brain functional connectivity with manual acupuncture in healthy subjects: An electroencephalograph case studying

Manual acupuncture is widely used for pain treatment and stress control. Previous studies on acupuncture have shown its modulatory effects on functional connectivity associated with one or a few preselected brain regions. To investigate how manual acupuncture modulates the organization of functional networks at a whole-brain level, we acupuncture at ST36 of right leg to obtain electroencephalograph (EEG) signals. By coherence estimation, we determine the synchronizations between all pairwise combinations of EEG channels in three acupuncture states. The resulting synchronization matrices are converted into functional networks by applying a threshold, and clustering coefficients and path lengths are computed as a function of threshold. The results show that acupuncture can increase functional connections and synchronizations between different brain areas. For a wide range of threshold, the clustering coefficient during acupuncture and post-acupuncture period is higher than that during the pre-acupuncture control period, whereas characteristic path length is shorter. We provide further support for the presence of "small-world" network characteristics in functional networks by acupuncture. These preliminary results highlight the beneficial modulations of functional connectivity by manual acupuncture, which could contribute to the understanding of acupuncture effects on the entire brain, as well as the neurophysiological mechanisms underlying acupuncture. Moreover, the proposed method may be a useful approach to the further investigation of the complexity of patterns of interrelations between EEG channels.     

鳍线过渡段的实验研究(英文)

本文提出了一种新型鳍线过渡段结构。这种结构是沿鳍线纵向轴线在基片上切一楔形凹槽,该凹槽与金属鳍渐变段一起提供空气填充波导和鳍线之间的阻抗匹配。对于不同渐变过渡段长度,其最佳楔形凹槽深度由实验试凑法得到。与普通渐变过渡段结构相比较,在X波段的大部分范围内,这种新型结构可使回波衰耗降低约10分贝。     

基片偏压对反应性RF溅射ZnO膜结构的影响

氧化锌(ZnO)属于纤维矿型结构,是一种兼备多种功能(半导性、压电性、光电特性、萤光性等)的物质。ZnO薄膜作为重要的电子材料而引入注目。为此,正在积极进行对ZnO薄膜晶体结构的研究。广泛采用的制膜方法是RF溅射法。本实验是采用金属锌靶的反应性RF溅射法沉积ZnO薄膜的,研究了反应性气体混合     

低温烧结0.5CaTiO3-0.5CaTiSiO5高频介质陶瓷

对添加2ZnO-B2O3玻璃实现0.5CaTiO3-0.5CaTiSiO5 高频介质材料900℃下低温烧结进行了系统研究。实验结果表明:添加质量分数为5%~10% 2ZnO-B2O3玻璃可使体积密度达到0.5CaTiO3-0.5CaTiSiO5理论密度的97%以上,且介电性能优异,r = 58~76,tg? 3.3?04,= (329~472)?06/℃,? 1012 cm。利用XRD、SEM和介电测量技术分析材料的晶相组成、显微结构和介电特性发现:材料由三种晶相组成,分别是单斜型CaTiSiO5、正交型CaTiO3以及一个新相,新相的生成可能是在液相烧结后期2ZnO-B2O3 玻璃在晶界处结晶而形成,低温烧结0.5CaTiO3-0.5CaTiSiO5 介质材料的介电性能很好地遵循李氏对数混合法则。     

磁力弹簧式气体隔膜泵的研究

提出了利用磁力弹簧构造气体隔膜泵,并对气体隔膜泵的具体结构与工作原理进行阐述。对气体隔膜泵的核心部件压电振子、被动截止阀等进行选择和设计;对磁力弹簧结构进行分析,通过理论计算确定磁力弹簧的轴向力与轴向间隙的关系;通过实验方法,对不同阀口直径气体隔膜泵的输出流量与压力进行验证。结果表明,磁力弹簧构造气体隔膜泵能大幅提高泵体容积变化率,磁力弹簧能提供很好的刚度,输出流量、压力与同类气体泵相比大幅提高。