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501.
The calculations developed in this paper aim at determining the optimal conditions of a NQR experiment when a transition is monitored by means of a pulse train with pulses of identical duration and signal acquisition after each pulse; coherences are assumed to vanish by effective transverse relaxation prior to every new pulse. These calculations demonstrate that, as in NMR, a steady state is effectively reached for any value of the recycle time. However, by contrast with NMR, it is shown that, for optimal data averaging under steady state conditions, the recycle time T can be kept as low as possible (the only limitation is the acquisition time). Nutation curves (signal amplitude versus pulse length) calculated in the steady state case are shown to depend strongly on the ratio T/T 1 (T 1: longitudinal relaxation time). The signal growth as a function of T/T 1under averaging of the first transients has been evaluated as well as the number of pulses necessary for reaching a steady state. 相似文献
502.
为了适应MEMS引信微型传爆序列的需求,针对微型雷管装药高度比对输出威力的影响开展了专门研究。改变装药直径为0.9 mm、装药高度为3 mm的微型雷管中起爆药与猛炸药装药高度比,用猛铜压阻传感器对爆轰输出压力进行测定,得到微型雷管中起爆药的临界高度为0.36 mm。当起爆药高度为1.65 mm时,微型雷管爆轰压力值最大,为10.3 GPa;当起爆药高度小于1.65 mm,HMX炸药高度大于1.35 mm时,随着起爆药高度的减小,猛炸药高度的增加,微型雷管的爆压值减小;当起爆药高度大于1.65 mm、HMX炸药高度小于1.35 mm时,随着起爆药高度的增加,猛炸药高度的减小,微型雷管的爆压值也减小。初步得出了羧铅起爆药和猛炸药的最佳高度比范围为0.69~2.26。 相似文献
503.
提出和分析了一种新的开关DC-DC变换器控制方法,基于电流基准的脉冲序列(current referenced pulse train,CR-PT)控制方法.CR-PT控制方法通过在每个开关周期检测和比较变换器的输出电压和负载电流,在多个等级不同的预设脉冲中选取其一作为该周期的有效控制信号.以Buck变换器为例对CR-PT控制方法的工作原理、实现方式、控制规律、稳态和瞬态特性进行了详细研究.研究结果表明:CR-PT控制在具有瞬态响应速度快、设计和实现简单易行稳定性好等优点的同时,其稳态性能远优于已有的脉冲序列控制. 相似文献
504.
高速大容量光纤光栅解调仪的研究 总被引:4,自引:0,他引:4
采用半导体光放大器和可调谐法布里-珀罗滤波器,以环路结构组成高速扫描激光器,结合光耦合器、光环路器和光电二极管等,形成4通道大容量高速光纤光栅解调仪。系统采用2kHz的类三角波调制信号,驱动法布里-珀罗滤波器在50nm的光谱范围内进行快速扫描。通过引入光纤梳状滤波器和单峰滤波器组成的参考通路,消除法布里-珀罗滤波器的非线性效应和扫描波长漂移问题,使得解调仪具有很好的稳定性和线性度。高速光纤光栅解调仪的稳定性为2pm,分辨率为1pm,线性度为0.99957,测量精度为5pm,解调频率为2kHz。 相似文献
505.
Deniz Ulusarslan 《Particle & Particle Systems Characterization》2012,29(3):167-177
This study investigated the experimental coefficient in the mathematical correlation for the pressure gradient of spherical capsule train flow according to flow regimes. The investigation was carried out in the 1.2 × 104 < Re < 1.5 × 105 range and under transport concentration of 5 – 30 %. Deviation between the pressure drops measured by experiment and the mathematical correlation was calculated based on new experimental coefficients. The total pressure gradient in the two‐phase flow of the mixture was distinguished as pressure gradients caused by homogeneous flow and those caused by pressure drops, depending on the rotational movement of the capsules. The experimental findings indicate that at lower concentrations, the losses caused by the rotational movement are low, but the losses caused by the homogeneous flow are high. Losses caused by the rotational movement increase as the concentration increases. 相似文献
506.
Luz Vianey Vela-Arevalo Roberto Alejandro Ku-Carrillo Sandra Elizabeth Delgadillo-Aleman 《Mathematical Methods in the Applied Sciences》2020,43(14):8006-8014
In this work, we construct simple models in terms of differential equations for the dynamics of pest populations and their management using biological pest control. For the first model used, the effect of the biological control is modelled by a function of repeated infinite impulses. And, our second model uses a periodic function proportional to the population to model the effect of biological control. In both cases, we present analytical solutions and derive a discrete version of them. Moreover, convergence conditions are given for periodic solutions. Finally, an application of such models is described for diamondback moth in a plot of broccoli to be controlled by the application of biological pesticides and beneficial parasitoids. 相似文献
507.
研究分析了已有NBP网络学习算法样本学习速度慢以及样本个体误差较大的原因,并在此基础上提出了一种基于训练集递减的自适应增强组合算法.通过对个体样本误差分布、泛化特性等方面的实例分析表明,该算法具有良好的泛化特性,既提高了样本学习速度,又改善了样本个体误差. 相似文献
508.
王东海 《宁波大学学报(理工版)》1994,(1)
本文针对进口螺杆压缩机中的高速驱动齿轮,对其进行了玻坏失效分析和几何参数测定。根据工作特点、运行情况和破坏现象,在选材、设计、制造、热处理和工艺参数选择等方面进行了改进性设计,达到了原设备的使用要求。本文所提供的设计方法对进口零、部件国产化的研制具有一定的参考、借鉴意义。 相似文献
509.
高速摄影系统的信息量 总被引:1,自引:1,他引:0
根据光学信息论,得到了高速摄影系统的信息量表达式.指出:高速摄影所记录的信息量与目标、高速摄影系统的参数及使用条件有关. 相似文献
510.
LIANG Fu-Tian GONG Datao HOU Suen LIU Chonghan LIU Tiankuan SU Da-ShunG TENG Ping-Kun XIANG Annie YE Jingbo JIN Ge 《中国物理C(英文版)》2013,(11):45-48
An all-transistor active-inductor shunt-peaking structure has been used in a prototype of 8 Gbps high- speed VCSEL driver which is designed for the optical link in ATLAS liquid Argon calorimeter upgrade. The VCSEL driver is fabricated in a commercial 0.25 p~m Silicon-on-Sapphire (SOS) CMOS process for radiation tolerant purpose. The all-transistor active-inductor shunt-peaking is used to overcome the bandwidth limitation from the CMOS pro- cess. The peaking structure has the same peaking effect as the passive one, but takes a small area, does not need linear resistors and can overcome the process variation by adjust the peaking strength via an external control. The design has been taped out, and the prototype has been proven by the preliminary electrical test results and bit error ratio test results. The driver achieves 8 Gbps data rate as simulated with the peaking. We present the all-transistor active-inductor shunt-peaking structure, simulation and test results in this paper. 相似文献