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191.
We apply a Runge-Kutta-based waveform relaxation method to initial-value problems for implicit differential equations. In the implementation of such methods, a sequence of nonlinear systems has to be solved iteratively in each step of the integration process. The size of these systems increases linearly with the number of stages of the underlying Runge-Kutta method, resulting in high linear algebra costs in the iterative process for high-order Runge-Kutta methods. In our earlier investigations of iterative solvers for implicit initial-value problems, we designed an iteration method in which the linear algebra costs are almost independent of the number of stages when implemented on a parallel computer system. In this paper, we use this parallel iteration process in the Runge-Kutta waveform relaxation method. In particular, we analyse the convergence of the method. The theoretical results are illustrated by a few numerical examples. 相似文献
192.
设计、建造了一台不对称结构、分布式负载有界波电磁脉冲(EMP)模拟器(MDES-60)。模拟器平行极板间区域长5 m,宽2 m,高1 m。测试结果显示模拟器工作空间电场幅值分布均匀、波形后沿基本无反射。表明通过缩小前过渡段的锥角、加宽下极板调整特性阻抗及采用分布式负载等措施取得了很好效果。配套不同的脉冲源,该模拟器可模拟IEC61000-2-9、Bell实验室、1976年出版物等多种脉宽标准的EMP波形,场强幅度范围15~60 kV/m,可用于短线缆响应实验或小型电子设备的考核效应实验。 相似文献
193.
194.
Fast light of CsI(Na) crystals 总被引:1,自引:0,他引:1
The responses of different common alkali halide crystals to alpha-rays and gamma-rays are tested in this research. It is found that only CsI(Na) crystals have significantly different waveforms between alpha and gamma scintillations, while others do not exhibit this phenomena. The rise time of the fast light is about 5 ns and the decay time is 17±12 ns. It is suggested that the fast light of CsI(Na) crystals arises from the recombination of free electrons with self-trapped holes of the host crystal CsI. Self-absorption limits the emission of fast light of CsI(Tl) and NaI(Tl) crystals. 相似文献
195.
The powerful capabilities of electronic digital signal processing and digital-to-analog conversion for implementing waveform generation in an optical transmitter are illustrated by considering pre-compensation for optical filtering, fiber dispersion, and nonlinear modulation dynamics. 相似文献
196.
We demonstrate photonically-assisted generation of RF arbitrary waveforms using planar lightwave circuits (PLCs) fabricated on silica-on-silicon. We exploit thermo-optic effects in silica in order to tune the response of the PLC and hence reconfigure the generated waveform. We demonstrate the generation of pulse trains at 40 GHz and 80 GHz with flat-top, Gaussian, and apodized profiles. These results demonstrate the potential for RF arbitrary waveform generation using chip-scale photonic solutions. 相似文献
197.
Xin Zhou Xiaoping Zheng He Wen Hanyi Zhang Yili Guo Bingkun Zhou 《Optics Communications》2011,284(15):3706-3710
We propose and experimentally demonstrate an all optical arbitrary waveform generation by optical frequency comb (OFC) based on cascading intensity modulation. By selecting spectral lines of interest from OFC through optical filters, 10 GHz, 20 GHz, and 60 GHz sinusoidal signals with low phase noise and more complex waveforms, including ultra-short pulse, half-wave cosine, and single frequency modulated MMW signals, are generated easily. 相似文献
198.
Switchable down-, up- and dual-chirped microwave waveform generation with improved time-bandwidth product based on polarization modulation and phase encoding 下载免费PDF全文
Yuxiao Guo 《中国物理 B》2022,31(7):78403-078403
A switchable down-, up- and dual-chirped microwave waveform generation technique with improved time-bandwidth product (TBWP) is proposed and demonstrated based on a dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) cascaded with a polarization modulator (PolM). By properly controlling the phase shifts of the radio frequency signals applied to the DP-DPMZM, switchable down-, up- and dual-chirped waveforms with simultaneous frequency and bandwidth doubling can be generated. To enlarge the TBWP further, splitting parabolic signal and phase-encoding splitting parabolic signal are used to drive the PolM for the enhancement of bandwidth and time duration. Numerical results demonstrate the generation of down-, up- and dual-chirped microwave waveform with TBWP of 8, 160 and 10240. The proposed method may find applications in future multifunction radar systems due to the high performance and flexibility. 相似文献
199.
200.
Abstract: A new simple digital positron lifetime spectrometer has been developed. It includes a DRS4 waveform digitizing board and two scintillation detectors based on the XP2020Q photomultiplier tubes and LaBr3 scintillators. The DRS4 waveform digitizing can handle small pulses, down to few tens of millivolts, and its time scale linearity and stability are very good. The new system has reached a 206 ps time resolution, which is better than the conventional analog apparatus using the same detectors. These improvements make this spectrometer more simple and convenient in comparison with other spectrometers, and it can be applied to the other scintillation timing measurements with picosecond accuracy. 相似文献