常压空气亚微秒脉冲DBD高速摄影研究

为研究亚微秒脉冲激励常压空气介质阻挡放电(DBD)时空演化规律,采用高速摄影相机(ICCD)在ns量级时间曝光范围内,分别在单次及连续放电(500Hz)情况下研究放电等离子体的发光性质及放电发展过程。结果表明:在亚微秒高压脉冲平行板结构放电条件下,起始阶段放电表现出不均匀性,随着电流增大发光增强并变得均匀,在回路电流最强位置时放电达到均匀状态,并且放电均匀性在回路电流下降阶段明显好于其上升沿阶段,放电发光强度与电流波形可以很好的吻合。在一定外界参数条件下,二次放电的存在受到电源重复频率、电压幅值等参数的影响。在单次放电条件下可以明显观测到二次放电的存在,相较于一次放电,二次放电更加均匀;连续状态放电模式下几乎观察不到二次放电。     

聚酯薄膜复合材料带状脉冲形成线传输介质

介绍了一种电气绝缘柔软复合材料——DMD膜,通过对膜结构的分析,设计了一种串联等效电路模型对其进行分析。运用该模型,对DMD膜在浸渍前和浸渍后两种情况下的介电常数和介电强度进行了求解并给出计算公式。从公式可以看出:DMD膜的介电常数在浸渍前后有明显的变化,浸渍后的介电常数得到了显著的提高,并且变化率较小;浸渍后DMD膜的介电强度高于未浸渍DMD膜的介电强度。当浸渍料介电常数愈大,聚酯材料上承受的电场强度愈大,浸渍料上承受的电场强度愈小,由于聚酯材料的耐压强度很高,所以整个传输线的介电强度得到提高。     

Detailed electrical measurements on sago starch biopolymer solid electrolyte

The biopolymer solid electrolyte has been synthesized and characterized. Potassium iodide (KI) has been added in polymer matrix to develop solid polymer electrolyte. Relationships between electrical, ionic transport parameter and mechanism have been studied in detail. Impedance spectroscopy reveals the detailed electrical studies and ion transport mechanism. The ion dissociation factor is compared with a measured dielectric constant at a fixed frequency. The dielectric data are calculated which support the ionic conductivity data.     

Dielectric studies of the phase transition in {N(CH3)4}2HgCl4

Dielectric properties of single-crystal {N(CH₃)₄}₂HgCl₄ (structure at room temperature; orthorhombic Pmcn) have been measured in a temperature range from 4 K to about 370 K. The dielectric constant along the a-, b-, and c-axes shows a break at 278 K. No other anomalies are detected in the temperature range studied. The transition temperature increases linearly with increasing hydrostatic pressure at a rate of 0.20 K/MPa. Twin boundaries are observed in the low-temperature phase on b-plate specimens. The results indicate that the phase transition in {N(CH₃)₄}₂HgCl₄ is ferroelastic, as in {N(CH₃)₄}₂XBr₄ (X: Mn, Co, Zn).     

Thermoelectric and dielectric investigations of the thermochromism of various na-acetylacetonate phases and intermediates

Sodium acetylacetonate was prepared by the interaction of sodium metal with acetylacetone. A fresh sample and various samples preheated at various temperatures were carefully prepared. Measurements were made by x-ray diffraction, IR absorption spectroscopy and differential thermal analysis (DTA). The temperature dependence of the electrical and dielectric properties of selective batches of Na-acetylacetonate phase and intermediates was measured.     

Determination of the Coefficient of Laser Radiation Reflection from Dielectric Targets in Vacuum

We present the results of experimental determination of the coefficients of laser radiation reflection (₁ 10.6 m and ₂ 1.06 m) from dielectric targets of complex chemical composition in vacuum with allowance for a regime of developed plasma formation.     

用边界元法分析非均匀介质中的传输线

 从静电场边值问题的积分解出发,推导出用边界元法求解分区均匀介质填充传输线问题的矩阵表达式,给出传输线电容参数的计算公式,介绍用边界元法求解分区均匀介质填充传输线问题的基本原理和求解过程。对两类传输线的计算结果表明：用边界元法求解分区均匀介质填充传输线问题,不仅具有较高的计算精度,而且可以很方便地应用于各类复杂截面分区均匀介质填充传输线问题的工程设计与计算,边界元法是求解分区均匀介质填充传输线问题的一种有效方法。     

Investigation of scattering of elastic waves by cylinders in 1-3 piezocomposites

The scattering behavior of P-waves in piezoelectric composites with 1–3 connectivity is studied. The method of wave function expansion is adopted for the theoretical derivations. Analytical expressions are obtained for the distributions of mechanical displacement in z-direction along the circumferences of piezoelectric cylinders. These solutions are used to study the influence of each element of the stiffness matrix and the piezoelectric matrix on the various resonant modes of vibration. Numerical results obtained indicate that perturbations of the elements c₄₄ and e₁₅ significantly affect resonant frequencies and amplitudes, perturbations of c₁₁ and c₁₂ have pronounced effects on resonant modes of high frequencies also. However, the resonant modes are not so sensitive to the perturbations of c₁₃, e₃₁ and e₃₃. The dynamic characteristics of 1–3 connectivity piezoelectric composites exposed here are meaningful for the design and manufacture of sensor/actuator elements by this kind of composites as well as the on-line health monitoring of the mechanical properties variations of the composites itself.     

(Na1/2Bi1/2)Cu3Ti4O12陶瓷的微观结构和电学性质

利用固相反应法在不同烧结温度条件下制备了一系列(Na_1/2Bi_1/2)Cu₃Ti₄O₁₂(NBCTO)陶瓷样品,研究了它们的晶体结构、微观组织结构、介电性质和复阻抗及其随温度的变化. 实验发现NBCTO陶瓷所呈现出的电学性质与CaCu₃Ti₄O₁₂陶瓷相应的电学性质非常类似. 烧结温度为990℃至1060℃范围的NBCTO陶瓷样品室 关键词： 高介电材料 介电性质 复阻抗 内阻挡层电容