单片机波形发生器的设计

本文介绍一种利用８０３１单片机构成的波形发生器，对波形产生的原理、方法、频率控制及幅度控制进行了叙述，给出了详细的硬件原理图，主程序流程图及部分子程序流程图。     

Complex Behavior in an Integrate-and-Fire Neuron Model Based on Small World Networks

Based on our previously pulse-coupled integrate-and-fire neuron model in small world networks, we investigate the complex behavior of electroencephalographic （EEG）-like activities produced by such a model. We find EEG-like activities have obvious chaotic characteristics. We also analyze the complex behaviors of EEG-like signals,such as spectral analysis, reconstruction of the phase space, the correlation dimension, and so on.     

WAVEFORM RELAXATION METHODS AND ACCURACY INCREASE

ＷＡＶＥＦＯＲＭ　ＲＥＬＡＸＡＴＩＯＮ　ＭＥＴＨＯＤＳ　ＡＮＤ　ＡＣＣＵＲＡＣＹ　ＩＮＣＲＥＡＳＥＷＡＶＥＦＯＲＭＲＥＬＡＸＡＴＩＯＮＭＥＴＨＯＤＳＡＮＤＡＣＣＵＲＡＣＹＩＮＣＲＥＡＳＥ￥ＳｏｎｇＹｏｎｇｚｈｏｎｇ（ＮａｎｊｉｎｇＮｏｒｍａｌＵｎｉｖ...     

高场不对称波形离子迁移谱快速检测水样中苯含量

建立了高场不对称波形离子迁移谱(FAIMS)检测水中苯含量的分析方法。研究了不同分离电压(Dispersion voltage,DV)下的苯标准谱图,获得用于苯识别的非线性函数二阶α2及四阶α4系数值分别为-3.8×10-5Td-2和5.1×10-8Td-4;通过平衡灵敏度与分离度,得到用于苯识别的最佳分离电压为800 V;通过不同质量浓度(0.08~0.64 mg/L)的苯样品与苯离子信号强度的关系,确定高场不对称波形离子迁移谱(FAIMS)对水中苯的检出限为0.89μg/L,远优于国家饮用水中苯浓度的限值10μg/L。本研究为水中苯检测提供了一种快速、高灵敏的方法。     

Application of frequency-domain waveform inversion method in Marmousi shots data

Frequency-domain waveform seismic tomography includes modeling of wave propagation and full waveform inversion of correcting the initial velocity model. In the forward modeling, we use direct solution based on sparse matrix factorization, combined with nine-point finite-difference for the linear system of equations. In the waveform inversion, we use preconditioned gradient method where the preconditioner is provided by the diagonal of the approximate Hessian matrix. We successfully applied waveform inversion method from low to high frequency in two sets of Marmousi data. One is the data set generated by frequencydomain finite-difference modeling, and the other is the original Marmousi shots data set. The former result is very close to the true velocity model. In the original shots data set inversion, we replace the prior source with estimated source; the result is also acceptable, and consistent with the true model.     

Effect of Linewidth Enhancement Factor on Doppler Beat Waveform Obtained from a Self-Mixing Laser Diode

The asymmetry and fringe inclination of the sawtooth-like waveform observed in the self-mixing signal obtained from a semiconductor laser with optical feedback enable the direction discrimination of line-of-sight motion of external target surfaces. We investigated the effects of linewidth enhancement factor and feedback strength on the asymmetry and the direction of fringe inclination of the signal by numerical simulations. For the first time, we show that direction of the fringe inclination is determined not only by the direction of the target motion but also by the value of the linewidth enhancement factor.     

Improved partial response maximum likelihood method combining modulation code for signal waveform modulation multi-level disc

In this paper, we describe an improved adaptive partial response maximum likelihood （PRML） method combining modulation code tbr signal waveform modulation multi-level disc. This improved adaptive PRML method employs partial response equalizer and adaptive viterbi detector combining modulation code. Compared with the traditional adaptive PRML detector, the improved PRML detector additionally employs illogical sequence detector and corrector. Illogical sequence detector and corrector can aw）id the appearance of illogical sequences effectively, which do not follow the law of modulation code for signal waveform modulation multi-level disc, and obtain the correct sequences. We implement the improved PRML detector using a DSP and an FPGA chip. The experimental results show good performance. The higher efficient and lower complexity can be obtained by using the improved PRML method than by using the previous PRML method. Meanwhile, resource utilization of the improved PRML detector is not changed, but the bit error rate （BER） is reduced by more than 20%.     

荔枝蝽在荔枝上取食行为的刺探电位分析

利用刺吸电位技术(EPG)测定了荔枝蝽4龄若虫在寄主荔枝上的取食行为。结果表明,荔枝蝽在荔枝上取食过程中产生了5 种波形：分别为NP波（非刺探波）、α波（刺探波）、β波（撕裂植物细胞波）、γ波（取食波）、δ波（取食结束波），但对不同品种荔枝没有明显差别，表明荔枝蝽对不同品种荔枝没有明显取食选择性。研究结果对于揭示荔枝蝽及其寄主荔枝之间的互作关系具有一定的意义。     

LHCD系统微波激励源性能优化设计

使用数字锁相环技术实现一定带宽内高精度可调节的频率输出,解决了速调管长期工作后响应频率发生偏移,模拟锁相环无法工作在系统最佳频率的问题;在移相器后增加功率幅度控制电路,保证了线性放大器的输出功率不会受到相位调节的影响;设计了一种基于数模转换(D/A)技术与微波电调技术相结合的波形控制单元,解决了激励源输出波形不可控的问题。通过以上三方面的改进,完成了HL-2M装置LHCD系统微波激励源的性能优化设计。