超微粒SnO2薄膜器件气敏特性的研究

本文介绍了作者采用半导体IC平面工艺技术,成功地研制出了超微粒SnO_2薄膜器件,并对该器件的氧气敏感特性作了研究,得到了该器件的主要特性参数。对其灵敏度特性曲线的研究表明:该器件不仅对低浓度氧气敏感,而且对高浓度氧气也敏感;并得到了超微粒SnO_2薄膜器件灵敏度特性所遵循的客观规律,即logR_s=0.72logC+0.85。     

基于LabVIEW的脉冲大电流测试系统

基于图形化编程语言Lab VIEW,采用高速采样算法,搭建了脉冲大电流测试系统。系统主要通过程序控制数字多用表等仪器对同轴分流器上脉冲电压的参数进行数据采样,计算得到脉冲大电流具体参数。该系统同时考虑了采样时延、采样速率等因素,降低了测量不确定度。经实验验证,本测试系统可靠性强,测量准确度高。     

谐振式光子晶体光纤陀螺信号检测及处理技术研究

谐振式光子晶体光纤陀螺是一种具有小型化、高精度等潜在技术优势的新型光纤陀螺,是国内外惯性器件研究的一个重要发展方向。针对谐振式光子晶体光纤陀螺的结构和信号检测原理进行了详细的叙述,确定了基于FPGA的陀螺信号检测总体方案,陀螺信号处理及控制模块主要由频差信号解调、复合拍频检测、闭环反馈控制、数据编码输出以及调制信号模块组成;随后重点介绍了窄线宽半导体激光器的驱动控制方案,在调制解调及频率偏差检测方案上采用数字相敏检波器实现频率偏差检测,在谐振频率闭环跟踪锁定方案上采用数字PI控制器实现环路光频率控制;最后进行了谐振式光子晶体光纤陀螺实验测试系统搭建,以及谐振曲线测试和谐振频率闭环锁定测试。     

谐振式光纤陀螺用激光器最优工作区间探究

激光器为谐振式光纤陀螺(R-FOG)的关键器件,根据R-FOG对激光器的要求,提出了一种R-FOG用激光器最佳工作点及最优工作区间的确立方法,制定了激光器性能自动化测试方案,得到激光器光功率、中心波长与电流、温度的变化关系。由此推导出2个激光器电流与温度的最佳工作点,并利用拍频检测原理确立2个激光器电流与温度的最优工作区域。激光器最优工作区域的掌握,为其应用于R-FOG提供了详实的参数指标。     

考虑级间耦合的五级SICG发射过程动态仿真

为了研究同步感应线圈炮发射过程中的动态特性,建立了考虑驱动线圈级间耦合的五级同步感应线圈炮的机电模型,运用轴对称线圈磁场的数值算法和微分方程算法编写了发射过程动态仿真程序,通过对给定系统发射过程的动态仿真得出了驱动线圈电流、电枢电流,弹丸所受推力、弹丸速度以及位移等重要参数的动态曲线,分析了系统发射过程的动态特性。     

MOSFET开关过程的研究及米勒平台振荡的抑制

设计功率MOSFET驱动电路时需重点考虑寄生参数对电路的影响。米勒电容作为MOSFET器件的一项重要参数,在驱动电路的设计时需要重点关注。重点观察了MOSFET的开通和关断过程中栅极电压、漏源极电压和漏源极电流的变化过程,并分析了米勒电容、寄生电感等寄生参数对漏源极电压和漏源极电流的影响。分析了栅极电压在米勒平台附近产生振荡的原因,并提出了抑制措施,对功率MOSFET的驱动设计具有一定的指导意义。     

基于数字包络检波的RNSS通道时延标定方法

提出一种采用数字处理的时延测试方法,用于对导航卫星导航信号发射通道分数码片时延的精确测量。该方法是通过高速A/D（模/数）转换器,对导航卫星下行的BPSK（二进制相移键控）信号和卫星导航秒脉冲进行双通道采样,读取采样数据并进行数据处理。根据秒脉冲信号触发门限上升沿确定时延测量起点,对BPSK采样数据进行平方律检波,获取码片换相点,计算换相点和秒脉冲之间的分数码片时延,并进行滤波器时延校准,从而得到导航卫星发射链路的分数码片时延,该方法不需要进行伪随机信号的捕获和跟踪,测量精度主要取决于采样器采样率。通过在测试中使用一根校准电缆对该方法进行验证,验证结果表明,采用本文提出测试方法的测量误差优于0.3ns。     

基于嵌入式技术的B码信号中同步脉冲提取方法的研究

首先对B码信号进行了详细地码型介绍和理论分析,然后提出了一种利用嵌入式技术来提取B码信号中同步脉冲的方法。该设计的核心部分是一片CPLD芯片,其内部实现了B码同步脉冲上升延的提取,脉冲宽度调制等功能。对设计过程中出现的关键问题,如脉冲宽度检测和毛刺信号的消除,本文提出了解决方法,并给出了仿真结果。与传统的方法相比,该设计方案具有精度高,体积小,成本低,工作稳定等优点。     

超小型纳米级驱动装置控制系统的研究

本文介绍了根据压电元件快速变形所引起的惯性力和摩擦力实现纳米级驱动装置的原理。针对微位移器的静、动态特性，研制了新型微位移器驱动源。试验结果证明，该驱动源大大改善了微位移器的过渡过程和动态特性，满足微步距驱动装置控制和驱动的需要。     

等离子显示单元的器件特性

研究等离子显示器发展的Illinois大学的器件研究所为了解这种器件的基本特性已提供的方便。结果做出一种器件模型,它目前正用来设计电子驱动电路。本文叙述一种等离子显示单元的器件特性和给出一种模型,它说明了这种双稳态单元的控制作用。此外,还讨论了用该模型设计显示驱动系统的问题。     

Optical Ranging System Employing a High Power Injection Laser Diode

For many military applications small, lightweight range finders are required that operate at a high pulse repetition rate. It will be shown that a ranging system with an injection laser in the transmitter can fulfill these requirements. The performance of an optical ranging system employing a pulsed gallium arsenide laser diode transmitter, with peak powers up to 100 watts at room temperature is described. After a brief review of fundamental system parameters, calculations of the range capability of the system are given, based upon the Poisson distribution of photoelectron statistics. A discussion is presented on the experimental support of theoretical analysis.     

FM/AM Noise Test Set for a Pulsed Doppler Radar

A new test method to measure the amplitude noise and phase noise in both CW and pulsed CW signals of a Ku-band pulsed Doppler radar is described. These noises are measured in a simulated environment of radar operation; thus the test results may give direct information to determine radar subclutter visibility. In comparison with the conventional noise test method, this new method not only gives more meaningful results but also can obtain results much faster in testing. Actual test system design is described by block diagrams and theoretical analysis. A method to determine approximate frequency jitter in a transmitter signal is also described.     

两种切割方法的TC1板材拉伸性能研究

为了研究激光切割和机械加工两种方法在钣金件切边中对工件的影响,采用激光切割和机械加工两种方法制作拉伸试件,并利用CMT6000微机控制电子万能试验机在常温条件下完成了拉伸试验.通过对试验结果的分析整理完成了两种方法的对比,结果表明:激光切割试件和机械加工试件得到的两组拉伸曲线在颈缩后有明显区别,激光切割的试件在拉伸过程中没有明显颈缩,且延伸率明显小于机械加工试件的延伸率.     

虚拟仪器技术在航空发动机智能检测中的应用

利用NI公司的LabW indows/CVI虚拟仪器作为开发平台,设计了一套适用于某型航空发动机地面试车的智能检测系统。实际检测结果表明:该系统较真实地反映了被测航空发动机的试车参数、工作状态及试车曲线。与传统的检测方法相比,既节省了成本,又提高了检测效率。     

Semi-analytical model for flat indentation of metal materials and its applications

The increasing use of small material components in a wide range of industrial fields necessitates the development of an accurate and robust indentation testing method. To this end, this paper proposes an Energy-density-equivalence for a Flat Indentation (E-FI) model based on the energy density equivalent principle. The proposed model describes the relationships among the material parameters of Hollomon’s power law (H-law), flat indenter diameter, energy, and indentation displacement. An E-FI Method (E-FIM) that determines the H-law parameters of materials through the indentation test is also developed. The energy-displacement curves forward-predicted by the E-FI model (based on known H-law parameters of materials) and the H-law parameters of materials given by the E-FIM (based on known energy-displacement curves) are consistent with the results of Finite Element Analysis (FEA) and the H-law parameters of materials used as the input for FEA, respectively. Using E-FIM, the goodness of fit for both stress–strain curves with H-law, predicted based on the displacement with 2% signal interference, and that for stress–strain curves without interference is more than 0.98. The stress–strain relations predicted by E-FIM were consistent with the results obtained via uniaxial tensile tests of ten ductile materials.     

Aeronautical use of semiconductor lasers for short optical pulses

In this paper, we investigate the feasible schemes to generate periodic optical pulses of width between several picoseconds (ps) and tens ps. Gain-switched semiconductor laser diodes are shown to be more suitable for avionics applications than mode-locked laser diodes. In the experiment, we use a low-cost Fabry-Perot laser diode to generate short optical pulse streams. A simple optical injection-locking scheme is then used to reduce the timing jitter and frequency chirp in such laser diodes, which in turn can improve the transmission performance of the generated optical pulses. It is expected that the use of gain-switched semiconductor lasers can meet the requirement of high-speed airborne communication networks or ground supporting systems at airports. Moreover, we discuss the possibility of using the pulsed semiconductor lasers to generate millimetre-wave (mm-wave) signals for future applications to airborne high-resolution, mm-wave radars.     

Fiber-optic radar calibration

A simple fiber-optic radar calibration target is described. Its operation is based on a wideband fiber, a laser transmitter that is directly modulated by the down-converted radar signal and an optical diode receiver recovering said signal. Further up-conversion having a common local oscillator with the first mixer ensures fidelity of the calibration return. Measured useful bandwidth exceeds 200 MHz and practically any radar RF frequency can be handled when suitable mixers are employed. Amplifiers can be added to the down-converted path as desired to compensate for the fiber loss. Modulation and LO sweep provide easy ways of introducing artificial fluctuations and Doppler frequencies. Particularly pulsed radars are readily tested with the proposed scheme as no restrictions are posed by the radar's TR-switch delays.     

功率MOSFET测试仪的设计

介绍了以单片机为核心的功率MOSFET测试仪的原理、系统结构及具体的软硬件设计。将脉冲功率法引入功率MOSFET跨导和沟道电阻的测试,很好地解决了大电流偏置下参数测试的散热问题。所设计的功率MOSFET测试仪可以进行功率MOSFET的耐压、沟道电阻、开启电压、跨导及输入结电容几个参数的精确测量,并已实用化。