面向空耦电声换能器应用的高性能FEP/PTFE复合膜压电驻极体

压电驻极体(也称为铁电驻极体)是一类具有强压电效应的微孔结构驻极体材料,具有柔韧、低密度、低特性声阻抗等特征,是制备柔性空气耦合声电换能器的理想材料.针对器件对高灵敏度和高温工作环境的应用需求,本文报道高性能氟化乙丙烯/聚四氟乙烯(FEP/PTFE)复合膜压电驻极体的制备和性能表征.研究结果表明,FEP/PTFE膜的特...     

二代高温超导带材的机械特性研究进展

以 YBCO(YBa2Cu3 O7 -δ ) 为代表的二代高温超导带材因具有高临界转变温度、 高临界磁场和强载流能力,受到了国际学界高度关注, 在各个领域具有广泛的应用前景. 二代高温超导带材在绕制、 冷却和运行过程中会受到不同来源的外力作用, 且超导带材的韧性、 延展性较差, 因此其机械性能是影响安全性与设备运行可靠性的关键.本文基于二代超导带材各向异性的特点, 对超导带材轴向、 横向、 弯曲三个方向的静态机械性能及疲劳性能进行了介绍. 同时, 也对超导带材各方向机械性能的测试方法、 影响因素及机理进行了总结     

球形钨合金破片空气阻力系数实验研究

 实验研究了理想球形钨合金破片和经历爆轰驱动的球形钨合金破片长距离飞行时的速度衰减规律。实验结果表明：（1）对于理想球形钨合金破片,在同一初始速度条件下,衰减系数为常数,空气阻力系数与初始速度有关,两者成线性关系;（2）对于经历爆轰驱动的球形钨合金破片,由于有轻微的质量损失和变形,速度衰减规律与理想球形钨合金破片有明显的区别,空气阻力系数与飞行速度有关,两者成线性关系。     

高能COIL偏振态的实验研究

 通过两块楔镜补充衰减和中性衰减片相结合的能量衰减方法,测得了功率密度为20 W/mm² COIL的偏振态。采用角反射器作为稳定腔折返装置,提高了激光能量分布的均匀性。激光光束分别以45°的入射角入射到两块楔镜上,被楔镜反射后,垂直通过中性衰减片,最后进入偏振态测试仪。实验结果表明：在腔内没有任何偏振选择器件和不加外部电磁场的情况下,采用折叠式稳定腔的横流双模块氧碘化学激光光束呈现部分偏振性质,而且在出光过程中偏振度逐渐降低。     

含铝炸药水下爆炸性能的实验研究

对RS211、HL-1、HL-2这3种含铝炸药和TNT炸药进行了水下爆炸实验,测量了4种炸药水下爆炸冲击波压力剖面和气泡脉动周期,获得了4种炸药水下爆炸冲击波的峰值超压、冲量、能量和气泡能。实验结果表明,在所研究的范围内,与TNT炸药相比,含铝炸药的冲击波能量有明显增加,约为TNT炸药的1.20～1.35倍,气泡能有显著增加,约为TNT炸药的1.50～2.30倍,表明在炸药中加入铝粉对于提高炸药水中爆炸威力是有益的。     

Experimentally Determining Bloch Parameters of Hamiltonian for Single-Qubit Systems

By considering the identification problem of unknown but fixed Hamiltonian H = S0σ0 ＋∑i=x,y,z Siσi where σi （i = x, y, z） are pauli matrices and σ0=I, we explore the feasibility and limitation of empirically determining the Hamiltonian parameters for quantum systems under experimental conditions imposed by projective measurements and initialization procedures. It may be unsurprising to physicists that one can not obtain the knowledge of So no matter what kind of projective measurements and initialization are permitted, but the observation draws our attention to the importance of the parameter identifiability under different experimental condition. It has also been revealed that one can obtain the knowledge of ｜Sz｜ and Sx^2＋Sy^2 at most when only the projective measurement {｜0/（0｜, ｜1/（1｜} is permitted to perform on and initialize the qubit. Further more, we demonstrated that it is feasible to distinguish ｜Sx｜, ｜Sy｜, and ｜Sz｜ even without any a priori information about Hamiltonian if at least two kinds of projective measurement or initialization procedures are permitted. It should be emphasized that both projective measurements and initialization procedures play an important role in quantum system identification.     

First-Principles Study of Electronic and Optical Properties of Y1-xCaxTiO3 （x=0, 0.25, 0.5, 0.75）

The full potential linearized augmented plane wave （FP-LAPW） method with the generalized gradient approximation （GGA） is applied to study the electronic and optical properties of perovskite-type compounds Y1-xCaxTiO3. The lattice parameters, magnetic moment, band structure, density of states and optical conductivity are obtained. The results show that the Ca ion plays an important role in the electronic properties and optical responses. Moreover, the optical properties including the dielectric function, absorption spectrum, extinction coefficient, energy-loss spectrum and refractive index are also discussed.     

截止波长12 μm的p型-InAs0.04Sb0.96材料的熔体外延生长

为了获得p-型的长波长InAsSb材料并研究掺杂剂Ge对材料特性的影响,用熔体外延法生长了掺Ge的波长为12 μm的p型-InAsSb 外延层.用傅里叶红外光谱仪、Van der Pauw 法和电子探针微分析研究了材料的透射光谱、电学性质以及组分的分布.结果表明,两性杂质Ge在熔体外延生长的InAs0.04Sb0.96材料中起受主杂质作用.当外延层的组分相同时,材料的截止波长不随掺Ge浓度的变化而变化,但是随着外延层中掺Ge量的增加,外延层的透射率下降.掺杂原子Ge在外延层的表面及生长方向的分布都是相当均匀的.77 K下测得,载流子浓度为9.18×1016 cm－3的掺Ge的p型-InAs0.04Sb0.96样品,其空穴迁移率达到1 120 cm2·Vs－1.     

Resonant Modes of L-Shaped Gold Nanoparticles

We analyze the electric field modes excited in resonant L-shaped gold nanoparticles using a finite-difference time domain method. Compared to a single gold nanorod, both the odd and even modes of the L-shaped nanoparticles can be excited due to the symmetry breaking. The nanoparticles with equal and unequal arms have different dependence of field enhancement and mode on the incident polarization.     

Linear Analysis of Folded Double-Ridged Waveguide Slow-Wave Structure for Millimeter Wave Traveling Wave Tube

A novel slow-wave structure （SWS）, the folded double-ridged waveguide structure, is presented and its linear gain properties are investigated. The perturbed dispersion equation is derived and the small signal growth rate is caleulated for dimensions of the ridge-loaded region and the parameters of the electron beam. The novel structure has potential applications in the production of high power and broad band radiation. For a cold beam, the linear theory predicts a gain of 1.1-1.27dB/period and a 3-dB small-signal gain bandwidth of 30% in W-band. A comparison between the folded double-ridged waveguide SWS and folded waveguide SWS （FWSWS） shows that with the same physical parameters, the novel SWS has an advantage over the FWSWS on the bandwidth and electron efficiency.