摘要：As a new three-dimensional(3-D)modulation,Polarization Quadrature Amplitude Modulation(PQAM) can be regarded as the combination of Pulse amplitude modulation(PAM) and Quadrature Amplitude Modulation(QAM) *** can better improve the digital communication efficiency and reduce the Symbol error rate(SER) of the system than one-dimensional or two-dimensional modulation *** to design a feasible constellation is the most concerned problem of PQAM *** paper first studies the relationship between the SER theoretical value of PQAM and the distribution of M and N,proposes a new M,N allocation ***,a new and straightforward design method of constructing higher-level 3-D signal constellations,which can be matched with the PQAM,and the constellation can divided into three different structures according to the ary for ***,the simulation results show that:in PQAM system,the modulation scheme and the constellation mapping scheme are proposed in this paper which can effectively reduce the system SER and improve the anti-noise performance of the system.

摘要：The central solenoid(CS) is an important component of China Fusion engineering Test Reactor, for producing, forming and stabilizing plasma in the superconducting tokamak. It is a complicated work to design and manufacture the large superconducting CS magnet, so it is meaningful to design a central solenoid model coil(CSMC) and analyze its electromagnetic properties in advance. In this paper, the structure, design parameters and magnetic field distribution of the CS model coil are discussed. The peak power of radial and axial turn conductors and time bucket loss are analyzed by using piecewise-linear method. The CSMC AC loss with different Nb3 Sn CICCs and AC loss of ITER CS coil are compared. The special electrometric method to measure AC loss of the CS model coil for future reference is presented.

摘要：The band structure of the confined states is calculated for Si/SiGe multi-quantum well infrared photodetector(M-QWIP).The influence of the Ge component in pseudosubstrate on the energy band structure of Si/Si0.54Ge0.46 multi-quantum wells(MQWs) is *** is found that the high energy levels in the MQWs move up while the low energy levels move down as the Ge component in pseudosubstrate *** influence of the barrier width on the energy band structure of MQWs is also studied based on the 6 × 6 k.p *** results show that the Si barrier between 5 nm and 10 nm is optimized to enhance the intersubband absorption in the MQWs.

摘要：The lifespan of biological heart valve prostheses available in the market is limited due to structural alterations caused by calcium phosphate deposits formed from blood plasma in contact with the *** objective of this work is to present a comparative methodology for the investigation of the formation of calcium phosphate deposits on bioprosthetic and tissue-engineered scaffolds in vitro and the influence of mechanical forces on tissue *** on earlier investigations on biological mineralization at constant supersaturation,a circulatory loop simulating dynamic blood flow and physiological pressure conditions was *** system was appropriately adapted to evaluate the calcification potential of decellularized(DCV)and glutaraldehyde-fixed(GAV)porcine aortic *** indicated that DCV calcified at higher,statistically nonsignificant,rates in comparison with *** difference was attributed to the tissue surface modifications and cell debris leftovers from the decellularization *** analysis of the solids deposited after 20 h by scanning electron microscopy in combination with chemical microanalysis electron-dispersive spectroscopy identified the solid formed as octacalcium phosphate(Ca8(PO4)6H2·5H2O,OCP).OCP crystallites were preferentially deposited in high mechanical stress areas of the test ***,GAV tissues developed a significant transvalvular pressure gradient increase past 36 h with a calcium deposition distribution similar to the one found in explanted *** conclusion,the presented in vitro circulatory model serves as a valuable prescreening methodology for the investigation of the calcification process of bioprosthetic and tissue-engineered valves under physiological mechanical load.

摘要：近年来,物质的拓扑相在整数维度的固态材料和经典波系统中得到了广泛的研究.然而,非整数维度中的拓扑物态几乎仍未被探索.分形是一类具有非整数维度的有趣且复杂的几何图形,其最大的特性是在不同的尺度上具有自相似性.本文基于谢尔宾斯基地毯结构,设计出一种具有分数维度的分形声学超材料,并证明了其具有分形特征的高阶拓扑态.同时由于该声学超材料的分形几何特性,其具有丰富的拓扑边缘态和拓扑角态.有趣的是,作者发现体态、边缘态和内角态的数量与该声学系统的自相似迭代次数成指数关系,且它们的豪斯多夫维数与系统的豪斯多夫维数相同.此外,通过数值仿真和实验验证,作者揭示了该分形声学超材料的拓扑角态具有新奇的频谱特征和丰富的模态振型.本工作将有助于推动未来非欧几何中拓扑现象的研究.

摘要：本文通过先进的实时原位磁性测试成功揭示了碱金属离子电池中的Li^(+)、Na^(+)、K^(+)的界面空间电荷存储机制.磁性测试结果表明,在FeSe_(2)等过渡族金属材料碱金属离子电池体系中,M^(+)(Li^(+)/Na^(+)/K^(+))和自旋极化电子可以分别存储在M2Se和Fe中,即界面空间电荷存储机制.这说明FeSe_(2)碱金属离子电池的储能机制不仅包含嵌入和转化反应,还包括界面空间电荷存储机制.此外,根据Fe/M2Se界面体系中空间电荷存储M^(+)的能力不同,磁学以及动力学测试结果进一步证明了碱金属离子半径是影响空间电荷存储的重要因素.该研究表明磁性测试是研究过渡族金属基材料的储能机制以及电化学过程中复杂界面效应的一种强有力的分析表征手段,为设计具有大存储容量和高功率密度的先进储能装置奠定了坚实的基础.

摘要：具有左手特性的超材料因具有超常物理特性近年来倍受关注,在微波工程领域也具有重要应用价值。本文设计了一种由多重嵌套方形开口环和一组平行金属线构成的夹芯结构超材料,采用有限元全波仿真软件HFSS系统研究了多重嵌套方形开口环数量对介电常数、磁导率和折射率的影响规律。结果表明,该超材料在8~18 GHz范围内的散射参数(S11和S21)具有显著的谐振特性,其内禀电磁参量也呈现出典型的双负左手特性,并得到了实验验证;且随着多重嵌套方形开口环数量的增加,其谐振峰数量也增加,当开口环数量为3时具有最大的有效频率带宽;进一步分析电磁场分布发现感应磁偶极子是导致强吸收的主要机制。这种结构简单、频率可调谐的超材料在选择性微波吸收材料和微波调制器件中具有广阔的应用前景。

摘要：二维范德华材料被广泛用作光分解水催化剂,但其直接的能量转化效率有待提高.因此,寻找具有高效光解水催化特性的二维材料成为理论和实验研究的热点.本文从量子力学第一性原理出发,预言了一类具有高效光解水特性的光催化剂:二维Ⅲ族硫化物Janus多层结构InGaXY,M2XY和InGaX2(M=In/Ga;X,Y=S/Se/Te).理论计算表明,多层材料的内建电场不仅可以促进光生载流子的空间分离,而且可以有效地调控材料能带的位置,提高能量转化效率.Janus多层材料能量转化效率的理论上限可以达到38.5%,接近了理论极限值(47%).更重要的是,在InGaSSe双层引入Ga空位可以有效降低析氢和析氧反应的过电势,仅仅依靠光生载流子提供的电压就可以驱动光解水催化反应.该理论结果不仅预言了二维Ⅲ族硫化物Janus多层材料可以作为高效的光解水催化材料,而且为设计和寻找高效光催化材料提供了新思路.

摘要：基于集成光学和硅光子学的光学神经网络硬件有很多优势:集成度高、速度快并且与CMOS工艺兼容.然而,目前的集成光学神经网络尺寸较大,很难扩展到大量神经元(>1000),实现大规模计算.本文提出了一种基于光学散射单元的神经网络硬件架构,除了具备一般光学神经网络的优势外,突出的优势是尺寸小,易于大规模扩展.光学散射单元允许光在一个小区域中发生散射,通过逆向设计散射区域结构,实现目标的计算功能.光学散射单元在一个很小的尺寸下,提供了很大的优化自由度,研究表明要实现一个4 4的矩阵乘法,计算单元尺寸只需要4 4μm^2.基于光学散射单元,本文设计了光学神经网络,在经典图像识别测试集MNIST上实现了97.1%的准确度.此外,这种光学散射单元还可以适用于相干光和非相干光.本研究提供了一个新的光学神经网络架构,能在不影响效率和功能下减小神经网络硬件尺寸.

摘要：作为碳中和的重要能源载体,利用可再生能源电解水制取的“绿色氢能”受到了全世界的关注.聚合物电解质水电解槽因其优越的性能,有望成为未来绿色制氢市场的主流.当前,聚合物电解质水电解槽的发展受到膜电极发展缓慢的制约.膜电极是聚合物电解质水电解槽的重要组成部分,在很大程度上决定了水电解槽系统的成本和性能.因此,必须从降低成本和提高性能方面对膜电极组件进行优化,以促进其发展.在这篇综述中,我们首先讨论了膜电极材料的最新进展及现有的设计策略,包括催化剂的成本、活性和稳定性、离聚物的分布和厚度以及离子交换膜的离子传输效率.然后分析了所有组分和层间界面对膜电极中离子、电子和物质传输的影响,以及对电解槽性能的影响.最后,本论文就催化剂活性、离子交换膜稳定性、相邻组分之间的界面以及性能评估方法等方面提出了相关建议和展望.