脉冲波形对牙齿温升过程的影响

为激光照射技术在临床牙齿疾病治疗中的应用提供理论依据,采用Crank-Nicolson有限差分法,求解热传导方程,模拟了Nd:YAG脉冲激光照射牙齿温升过程,研究了脉冲波形(矩形波、左三角波、正三角波、右三角波和高斯波等)对温升过程的影响.结果表明:矩形波照射时,牙齿表面温度最高,牙髓温度最低;高斯波照射时,牙齿表面温度最低,牙髓处温度最高.随着激光能量密度增大,不同波形照射引起的牙齿表面温差增大,牙髓温差减小.给出了5种波形照射牙齿表面时能量阈值.     

脉冲交互集值微分系统的严格稳定性

将常微分系统的严格稳定的概念发展到脉冲交互集值微分系统,利用Lyapunov函数方法和比较原理,在较弱的条件下研究了脉冲交互集值微分系统的严格稳定性,并得到了相应的结果.     

蒸汽发生器二回路过冷沸腾的数值模拟

为深入研究核电蒸汽发生器二回路侧汽液两相的沸腾传热和流动特性,采用RPI模型对过冷沸腾区域壁面的热流分配进行划分,以此修正CFD程序中的两流体模型,并利用文献中的实验结果验证了修正后模型的适定性.最后以大亚湾压水堆核电站为例,采用该模型对蒸汽发生器内二回路预热段单元通道内的过冷沸腾进行计算,获得了通道内流体空泡份额、速度、温度、热流量分配等的分布情况.     

自学习模糊脉冲神经网络的旋转机械诊断

针对旋转机械故障分类边界的模糊性和传统的神经网络算法难以解决应用问题的实例规模和网络规模之间的矛盾问题,提出了一种自学习模糊脉冲神经网络算法,该算法通过脉冲序列的种群编码和无监督学习较好的克服了旋转机械故障分类边界的聚类分析无效性问题.应用表明该算法有效解决了旋转机械故障的边界模糊性问题,较大提高了故障诊断的准确率.     

光阴极微波电子枪的时序同步

使用AVR单片机设计实现了合肥光源光阴极微波电子枪的时序同步电路,满足了该系统的特殊触发要求,帮助电子枪系统顺利实现出束;以极低廉成本实现了同类系统采用昂贵专用设备提供的功能;同时在实验结果基础上根据设计方案分析了信号抖动的来源,合理解释了抖动大小,并给出了提高精度升级系统的方案。     

脉冲参数对脉冲MIG焊焊接行为的影响研究

针对自行开发的软开关逆变电源,设计了脉冲参数影响规律研究的工艺实验平台。实验根据一脉一滴的原则,改变峰值电流、峰值时间、基值时间,采用小波分析仪采集焊接过程的电流电压信号,并用高速摄像机获取熔滴过渡图像,结合两者处理结果分析表明,脉冲参数直接影响熔滴过渡过程,峰值电流和峰值时间之积对熔滴过渡影响显著,基值时间和基值电流对熔滴过渡影响不大。     

一类带p-Laplace 算子的奇异脉冲特征值问题

利用锥上的不动点定理,研究一类带p-Laplace算子的奇异脉冲微分方程特征值问题,并给出正解存在的充分条件.     

Carrier-envelope phase locking of 5 fs amplified Ti:sapphire laser pulse at 1 kHz repetition rate

This paper reports the carrier-envelop phase （CEP） locking for the 5 fs re-compressed laser pulse generated from a chirped pulse amplified （CPA） Ti：sapphire laser at 1 kHz repetition rate. A phase locking feedback system with two loops was designed to control the fast fluctuation arising from the seeding laser and the slow fluctuation arising from the sub-mJ amplified pulse. The principle and structure of the phase control system, including the CEP detection, servo loop design and phase locking result, are analyzed. The experiment shows that our phase locking system can be well used to establish the stable phase locking of few-cycle amplified laser pulse, and the CEP variation of below 53 mrad （rms） was demonstrated during a locking period of more than 3 h.     

Control of the carrier-envelope phases of a synchronously pumped femtosecond optical parametric oscillator and its applications

The intrinsic synchronization, multi-color outputs and related carrier-envelope phases （CEP） among pulses bring advantages to synchronously pumped femtosecond optical parametric oscillators and the pumping sources for broadband frequency comb generation and ultrashort waveform coherent syn-thesis. In this paper, we discuss our latest research results in this field, which cover the following as-pects： the phase relationship and energy conservation law in an OPO and related experimental verifi-cation; control of the pumping Ti-sapphire femtosecond laser＇s CEP by self-referencing technology, and its repetition-rate locking by piezoelectric transducer （PZT）; CEP locking of the pulses from the OPO by beating the non-phase-matched visible outputs against pump supercontinuum to obtain a driving signal for a fast PZT on the OPO end mirror; the generation of a broadband frequency comb spanning from 400 nm to 2.4 μm with 1.2 kHz bandwidth; and the realization of coherent interference between phase controlled pump pulses and signal second harmonic pulses.     

Quantum coherent control of ultrashort laser pulses

The effective photonic control is one of the key issues in photo-physics. Significant advancement in photonic crystals, quantum optics, ultrafast optics as well as micro-nano-optics gives rise to new op-portunities to manipulate the emission and propagation in optical fields, leading to a number of new and interesting discoveries, e.g., ultrashort light pulse storage and efficient energy conversion. This paper reviews the latest research progress in storage, release and energy conversion for ultrashort laser pulses in periodical arrays of absorbing medium. Techniques to fabricate such devices are also presented.