数字电缆自动测试系统的准确性分析

本文介绍了数字电缆测试与早期通信电缆测试的不同要求,并给出了简要理论说明。通过不同条件下的同一盘电缆,同一台测试仪器的测试结果,表明引起测试结果改变的原因。最后具体说明了如何正确理解数字电缆自动测试系统测试结果和被测样品电缆的电性能参数的关系。     

Photoelectric properties of Cu2ZnSnS4 thin films deposited by thermal evaporation

正Sn/Cu/ZnS precursor were deposited by evaporation on soda lime glass at room temperature,and then polycrystalline thin films of Cu_2ZnSnS_4(CZTS) were produced by sulfurizing the precursors in a sulfur atmosphere at a temperature of 550℃for 3 h.Fabricated CZTS thin films were characterized by X-ray diffraction,energy dispersive X-ray spectroscopy,ultraviolet-visible-near infrared spectrophotometry,the Hall effect system,and 3D optical microscopy.The experimental results show that,when the ratios of[Cu]/([Zn]+[Sn]) and[Zn]/[Sn]in the CZTS are 0.83 and 1.15,the CZTS thin films possess an absorption coefficient of larger than 4.0 x 10~4 cm~(-1) in the energy range 1.5-3.5 eV,and a direct band gap of about 1.47 eV.The carrier concentration,resistivity and mobility of the CZTS film are 6.98 x 10~(16) cm~(-3),6.96Ω-cm,and 12.9 cm~2/(V-s),respectively and the conduction type is p-type.Therefore,the CZTS thin films are suitable for absorption layers of solar cells.     

一种判断气/固两相流流型的新方法

对于广泛应用于工业生产的气/固两相流,研制较好的仪器来测量其参数显得尤为重要。而且国内外许多学者都在致力于气/固两相流甚至多相流的研究,并取得了长足的进展。本文在简要介绍现阶段测量气/固两相流流型方法的前提下,提出一种新的判断气/固两相流流型方法。即基于概率密度定义,利用测量信号的均值进行直接判断。     

Carbon nanocones/discs – a new type of filler to improve the thermal and mechanical properties of polymer films

The mechanical characteristics and thermal properties of composite films based on the thermally stable aromatic polyimide (PI) (PMDA‐ODA) and carbon nanocones/discs (CNC) were studied. The introduction of CNC to PMDA‐ODA leads to the substantial increase of film stiffness. The Young's modulus values of the composite films are somewhat higher than those of the previously characterized composite films of this PI filled with nanoclay, carbon nanofibers, and asbestos‐like hydrosilicate nanotubes. The introduction of CNC into PMDA‐ODA (concentrations of CNC were up to 15 vol%) does not cause any marked aggregation of nanoparticles. The presence of CNC in the PI matrix does not affect the glass transition temperature of the polymer but hinders chain mobility at temperatures above T_g. This behavior makes it possible to increase the working temperature range of the composite films containing more than 5 vol% of CNCs, up to the temperature of thermal decomposition. The introduction of CNC into PMDA‐ODA leads to dramatic (～12 orders of magnitude) increase of active electrical conductivity of the material. Copyright © 2011 John Wiley & Sons, Ltd.     

Synchronization of coupled chaotic FitzHugh-Nagumo systems

This paper addresses dynamic synchronization of two FitzHugh-Nagumo (FHN) systems coupled with gap junctions. All the states of the coupled chaotic system, treating either as single-input or two-input control system, are synchronized by stabilizing their error dynamics, using simplest and locally robust control laws. The local asymptotic stability, chosen by utilizing the local Lipschitz nonlinear property of the model to address additionally the non-failure of the achieved synchronization, is ensured by formulating the matrix inequalities on the basis of Lyapunov stability theory. In the presence of disturbances, it ensures the local uniform ultimate boundedness. Furthermore, the robustness of the proposed methods is ensured against bounded disturbances besides providing the upper bound on disturbances. To the best of our knowledge, this is the computationally simplest solution for synchronization of coupled FHN modeled systems along with unique advantages of less conservative local asymptotic stability of synchronization errors with robustness. Numerical simulations are carried out to successfully validate the proposed control strategies.     

Effects of （LiCe） co-substitution on the structural and electrical properties of CaBi2Nb209 ceramics

The piezoelectric,dielectric,and ferroelectric properties of the(LiCe) co-substituted calcium bismuth niobate(CaBi2Nb2O9,CBNO) are investigated.The piezoelectric properties of CBNO ceramics are significantly enhanced and the dielectric loss tan δ decreased.This makes poling using(LiCe) co-substitution easier.The ceramics(where represents A-site Ca2+ vacancies,possess a pure layered structure phase and no other phases can be found.The Ca0.88(LiCe)0.04 0.04Bi2Nb2O9 ceramics possess optimal piezoelectric properties,with piezoelectric coefficient(d 33) and Curie temperature(TC) found to be 13.3 pC/N and 960 C,respectively.The dielectric and piezoelectric properties of the(LiCe) co-substituted CBNO ceramics exhibit very stable temperature behaviours.This demonstrates that the CBNO ceramics are a promising candidate for ultrahigh temperature applications.     

Negative Corona Discharge Ion Source Under Ambient Conditions with Mini Line-cylinder Electrodes

A novel ambient negative corona discharge ion source with mini line-cylinder electrodes is designed. The diameters of inner and outer electrode are 0.16 and 4 mm respectively. With a special assembly method, a perfect coaxiality of the two electrodes is obtained. An injection system utilizing a temperature control technique, achieves a constant and stable concentration of the sample, which is critical to the experiment. The formulas of the corona onset voltage of line-cylinder electrodes are also introduced. The experiment results show that negative substances such as formic acid and acetic acid can be ionized under ambient conditions. When combined with micro electrical mechanical system fabricationprocess, the volume of the ion source can be reduced dramatically, but there is an undesirable surface discharge. To solve the surface discharge problem, an improved structure was designed and tested. The simplicity of the interface of the ion source makes it suitable for mass spectrometer, micro mass spectrometer, ion mobility spectrometer, and high-field asymmetric waveform ion mobility spectrometer applications.     

高冲击随弹测试固态记录器的设计与应用

为记录爆炸高冲击信号,设计了随弹测试固态记录器。该固态记录器以FPGA器件XC2S30为核心处理芯片,在其内部的A/D控制器、高速状态机、相位延迟时钟和闪存控制器的共同作用下,能够将高冲击信号转换成数字信号并存储到由闪存构成的主存储器中。利用设计的固体记录器并结合多层缓冲和双层钢套保护结构,成功地记录了炮弹爆炸抛撒和炮击试验中的全程高冲击信号。     

多孔药型罩聚能射流的稳定性

基于Herrmann改进的Grneisen状态方程,对多孔药型罩受冲击压缩产生的温升进行了估算,从理论上分析了孔隙度对射流断裂时间的影响。使用脉冲X光测试并结合侵彻实验研究了药型罩初始孔隙度为9.3%和11.4%时聚能射流的稳定性。研究结果表明,在一定孔隙度范围内,射流的稳定性随孔隙度的增加而增强。     

小当量水中爆炸气泡的脉动现象

为研究水中爆炸气泡的脉动现象,设计了用于小当量(10 g TNT)水中爆炸研究的爆炸水箱,在爆炸水箱装置中进行了多次0.125、1.000、3.370、8.000 g TNT当量的PETN球形炸药水中爆炸试验。采用高速摄影系统获得了气泡脉动图片;给出试验范围内气泡脉动过程中气泡直径、速度及加速度随时间变化的拟合曲线。对气泡脉动直径和周期数据进行了分析,这些数据基本符合爆炸相似律。