菊花提取液用于啤酒发酵的研究

通过混合菊花提取液与大麦汁共同发酵来研制菊花啤酒,探讨了菊花浸提液添加量、菊花浸提液的添加时间及原麦汁浓度三个因素对菊花啤酒品质的影响.通过对比试验以及感官得分得出了菊花啤酒的最佳工艺条件为:菊花浸提液添加量为20%,原麦汁浓度12°P,在发酵后期加入.实验表明研制出的新型啤酒具有啤酒的清爽和菊花的香气.     

Chaotic system optimal tracking using data-based synchronous method with unknown dynamics and disturbances

We develop an optimal tracking control method for chaotic system with unknown dynamics and disturbances. The method allows the optimal cost function and the corresponding tracking control to update synchronously. According to the tracking error and the reference dynamics, the augmented system is constructed. Then the optimal tracking control problem is defined. The policy iteration(PI) is introduced to solve the min-max optimization problem. The off-policy adaptive dynamic programming(ADP) algorithm is then proposed to find the solution of the tracking Hamilton–Jacobi–Isaacs(HJI) equation online only using measured data and without any knowledge about the system dynamics. Critic neural network(CNN), action neural network(ANN), and disturbance neural network(DNN) are used to approximate the cost function, control, and disturbance. The weights of these networks compose the augmented weight matrix, and the uniformly ultimately bounded(UUB) of which is proven. The convergence of the tracking error system is also proven. Two examples are given to show the effectiveness of the proposed synchronous solution method for the chaotic system tracking problem.     

Laser diode pumped high-energy single-frequency Er:YAG laser with hundreds of nanoseconds pulse duration

We demonstrated a high-energy single-frequency erbium-doped yttrium aluminum garnet(Er:YAG)laser.With1470 nm laser diodes(LDs)as pumping sources,single-frequency laser pulses with energy of 28.6 m J,21.6 m J,and 15.0 m J are obtained at pulse repetition frequency of 200 Hz,300 Hz,and 500 Hz,respectively.As far as we know,this is the highest single-frequency pulse energy with the Er:YAG gain medium.With the ring cavity design,pulse duration is maintained at hundreds of nanoseconds.This high-energy single-frequency laser with hundreds of nanoseconds pulse duration is a prospective laser source for light detection and ranging applications.     

0.22THz折叠波导行波管电子光学系统设计与实验研究

设计了一套0.22THz折叠波导行波管电子光学系统,详细介绍了电子枪和周期永磁聚焦系统的设计过程,在电子枪电子束束腰与磁系统不匹配情况下,对磁场过渡区进行了优化设计,以此为基础利用磁场仿真软件对磁场进行模拟和优化,并把磁场位形代入电磁仿真软件进行电子束传输仿真,优化后的电子光学系统发射束流10mA,阴极电压15kV,束流通过率96%。通过实验验证,流通管束流通过率93%,高频样管束流通过率94%,与设计相符。高频样管实现连续波运行,功率大于0.4 W,3dB带宽大于12GHz。     

0.22THz宽带折叠波导行波管设计与实验

为了获得0.22THz宽带折叠波导行波管,对行波管的慢波结构和输入输出窗结构进行了宽带设计。通过理论分析和电磁仿真计算出合适的参数,使慢波结构在0.22THz工作点附近的色散曲线平坦,耦合阻抗变化小,模拟计算得到的慢波结构3dB带宽大于16GHz;通过对盒型窗结构及匹配段的优化计算,得到的输入输出结构在大于30GHz范围内S11参数小于-25dB。根据该设计进行了两轮制管和实验研究,得到了一支3dB瞬时带宽约8.8GHz,另一支3dB瞬时带宽大于12GHz的0.22THz折叠波导行波管,中心频率的峰值功率大于400mW。     

0.14THz返波管器件

对有限引导磁场环形电子束的色散曲线作了理论推导,并利用该色散关系数值计算了正弦慢波结构的色散曲线。采用KARAT模拟程序对0.14 THz返波管进行了粒子模拟,并在RADAN303脉冲源上开展了初步的实验研究,实验获得频率大于0.14 THz、脉冲宽度1~2 ns和辐射功率大于100 kW的太赫兹波输出。     

半导体抽运的Er:YAG陶瓷单频脉冲激光器

利用掺铒钇铝石榴石(Er:YAG)单块非平面环形腔(NPRO)激光器作为种子源,通过注入锁定技术研制了半导体抽运的Er:YAG陶瓷单频脉冲激光器。在重复频率为200Hz的条件下,获得了脉冲能量为11.45mJ、脉冲宽度为174ns的1645nm单频脉冲输出,在x和y方向上的M~2因子分别为1.45和1.42,脉冲光与种子光拍频信号的频谱半峰全宽为2.67MHz。实验表明,Er:YAG陶瓷作为增益介质在产生1.6μm激光方面具有较好的性能。此激光器可在激光雷达领域作为多普勒相干测风激光雷达和遥感激光雷达的光源。     

不同浓度氯化钠水溶液核磁共振特性的实验研究

为了认识氯化钠水溶液的核磁共振特性,配制了浓度在0%~24%范围内的氯化钠水溶液,采用CPMG自旋回波法测量了横向弛豫时间和信号强度,文章分析了氯化钠水溶液浓度与横向弛豫时间及信号强度之间的关系和影响机理。结果表明,氯化钠水溶液的横向弛豫时间随着浓度增加而减小,二者存在较好的线性关系;单位质量氯化钠水溶液的核磁共振信号强度随着浓度增加而减小,二者之间也存在着较好的线性关系。利用这两种关系均可实现氯化钠水溶液浓度的核磁共振测量。