用红外光谱技术研究打蜡梨的红外光谱特性

采用CCD阵列光谱仪研究了打蜡梨的红外光谱特性。经分析,在655~660 nm波段,经过打蜡处理后的梨会出现吸收峰,而未经打蜡处理的梨则没有出现吸收峰;在610~620 nm波段,打过石蜡梨的红外图谱吸收峰峰高和未打蜡梨的红外图谱吸收峰峰高相当,而打过果蜡梨的红外图谱吸收峰远远低于未打蜡梨的红外图谱吸收峰。该结果表明红外光谱技术在打蜡梨检测中具有一定的可行性,同时也为进一步研究针对打蜡梨的智能化无损检测技术提供了参考依据。     

无人机GPS信号的快速捕获与算法改进

无人机在空中侦察、监视、通信、反潜以及电子干扰等领域发挥的作用日趋重要,GPS技术已经成为无人机快速,安全,有效地执行任务的关键技术。传统的GPS信号捕获算法,每搜索一个多普勒频点需要进行两次FFT和一次IFFT,运算量大且实时性差。文中利用C/A码功率谱对称性的特点,通过减少参与循环的FFT点数的方法对传统的FFT算法做了改进并利用MATLAB进行了仿真,仿真结果表明,改进后的捕获方法能够在满足捕获精度的条件下,可以更快的完成捕获任务,有效地提升了导航定位的实时性。     

Spectrum‐Based Color Reproduction Algorithm for Makeup Simulation of 3D Facial Avatar

Various simulation applications for hair, clothing, and makeup of a 3D avatar can provide more useful information to users before they select a hairstyle, clothes, or cosmetics. To enhance their reality, the shapes, textures, and colors of the avatars should be similar to those found in the real world. For a more realistic 3D avatar color reproduction, this paper proposes a spectrum‐based color reproduction algorithm and color management process with respect to the implementation of the algorithm. First, a makeup color reproduction model is estimated by analyzing the measured spectral reflectance of the skin samples before and after applying the makeup. To implement the model for a makeup simulation system, the color management process controls all color information of the 3D facial avatar during the 3D scanning, modeling, and rendering stages. During 3D scanning with a multicamera system, spectrum‐based camera calibration and characterization are performed to estimate the spectrum data. During the virtual makeup process, the spectrum data of the 3D facial avatar is modified based on the makeup color reproduction model. Finally, during 3D rendering, the estimated spectrum is converted into RGB data through gamut mapping and display characterization.     

工业带材速度检测系统设计

为了解决工业带材生产过程中带材速度实时精确检测这一问题,设计了一种基于纹理图像功率谱的非接触式工业带材速度检测系统。首先利用线阵CCD采集带材图像的纹理图;然后对纹理图像进行滤波、二值化、腐蚀等预处理;最后对图像进行功率谱分析,利用霍夫变换求得带材图像功率谱分布方向,从而间接得到带材的速度。实验结果表明该方法检测工业带材速度的误差可以缩减到±0.03 m/s之内,能够有效、实时地测得工业带材的运动速度。     

Cu掺杂CaCu_3Ti_4O_(12)陶瓷的介电性能和晶界特征

采用传统的固相反应工艺制备了Cu掺杂的CaCu3Ti4O12(Cu-CCTO)陶瓷。采用Schottky热电子发射模型研究了其晶界特征。研究了保温时间对Cu-CCTO陶瓷的介电性能和晶界特征的影响。结果表明:保温时间从1 h延长到30 h,Cu-CCTO陶瓷在100 kHz下的介电损耗保持在0.135,相对介电常数由3 600增至20 000以上。随着保温时间的延长,Cu-CCTO陶瓷的I-V非线性系数由1.8增至3.37,但击穿电场强度却由1 500 V/cm降至约700 V/cm。随着保温时间的延长,Cu-CCTO陶瓷的势垒高度和耗尽层宽度均增加。     

基于物联网的智能节水灌溉控制网络设计

为提高灌溉用水的利用率和设备智能化程度,提出了一种基于无线传感器网络的智能节水控制系统。重点分析了应用于传感器网络中的路由协议,并实现了算法设计,将各传感器构成智能化传感器网络,同时引入太阳能供电电池,从而全面提升系统的自动化和智能化水平。采用网络仿真的方法对所提算法进行验证。仿真结果表明,该控制网络可显著改善灌溉的准确度,提高灌溉用水的利用效率。     

雷达目标信号模拟器的设计与实现

为满足雷达数据处理系统目标跟踪算法的测试需求,介绍了一种基于USB和FPGA技术的雷达目标信号模拟器设计方案。文中重点讨论了模拟器的结构和目标数据形成、传输、存储、信号波形产生等主要技术。该模拟器具有成本低、灵活性高的特点。实际应用表明该模拟器具有良好的性能,可以作为雷达数据处理系统的调试设备。     

Spread spectrum in three-phase inverter by an optimised dual randomised PWM technique

Randomised pulse width modulation (RPWM) technique has become a viable alternative to deterministic pulse width modulation (DPWM). By spreading the power spectrum in a continuous noise, this new technique better complies with electromagnetic compatibility (EMC) requirements for conducted electromagnetic interferences (EMI) and allows reducing the emitted acoustic noise in variable speed drives (VSDs). The most popular RPWM schemes are randomised pulse position modulation (RPPM) and randomised carrier frequency modulation (RCFM). The combination (RCFM-RPPM) or dual RPWM (DRPWM) has also been proposed. In this article, we propose an optimised DRPWM (ODRPWM) for the three-phase inverter. First, the modulating principle is proposed, and then, a mathematical model of power spectral density (PSD) of the output voltage is developed and validated for the three schemes, namely RPPM, RCFM and RCFM-RPPM. PSD analysis shows that the proposed scheme is more effective on spreading PSD. Moreover, this analysis reveals optimal parameters of randomisation for a maximum spread of the PSD. The optimisation problem is then modelled and solved using two powerful non-linear methods.     

基于DM642平台的智能视频分析系统设计

以DM642为核心,设计了一款智能视频分析系统,支持标清视频。采用模块化设计,通过视频智能分析,对目标实现了检测、识别、跟踪及预警功能。