Wireless sensor network is an emerging network technology in the 21st century. Its emergence brings a new phase in the development of network. Lately, there are more and more investigations on wireless sensor network MAC protocols. The research results on MAC protocol is summarized, some typical MAC protocols are analyzed, such as S-MAC, T-MAC, μ-MAC, and etc. A new power controlled sensor MAC protocol(PC-MAC) is introduced for wireless sensor networks, which can provide an effective mechanism for improving energy efficiencies for decreasing the transmitting power directly and avoiding collision. The simulation results show that energy can be saved up to 50%-96% by it.

A method to calibrate the errors of polarization information measured by division-of-focal-plane polarimeters is demonstrated. The principle of this method is explained, and its feasibility is verified by theoretical simulation and experiment. The simulation and experimental results show that this method can obviously improve the measuring precision of polarization information, and compared with other approaches, the proposed method just uses normal light sources, but can achieve comparable performance.

研究激光光束海面反射光强的方向分布特性对海上光电对抗等领域的工程实践具有重要意义. 本文采用分形方法模拟粗糙海面, 并在海面基准坐标系中建立起描述粗糙海面几何特征的数学方程, 然后基于蒙特卡罗方法模拟高斯光束, 依据几何光学原理在基准坐标系下推导了高斯光束的海面反射模型, 采用该模型可以编程计算激光光束海面反射光强的方向分布. 将模拟计算结果与实验结果进行了对比分析, 结果表明该模型可以较好地反映激光光束海面反射光强的分布趋势, 验证了模型的有效性.

A diode-end-pumped self-mode-locked Tm,Ho:LuLiF₄ (LLF) laser is demonstrated for the first time, to the best of our knowledge. At the incident pump power of 3.4 W, the stable self-mode-locked operation of the Tm,Ho:LLF laser was realized without any additional devices in the resonator. Further increasing the incident pump power to 6.8 W, the maximum average output power of 1.07 W was achieved at 2068 nm with a pulse width of 746 ps and a repetition frequency of 468 MHz. The experimental results indicate that the Tm,Ho:LLF crystal is promising to generate the high-power self-mode-locked solid-state laser at 2 μm waveband. The self-mode-locked Tm,Ho:LLF laser has potential applications in optical communication, remote sensing, material process, and nonlinear frequency conversion.

Operating range is an important indicator for determining the detection capability of an infrared search and track (IRST) system. To address the deficiencies of a traditional range model, such as excessive parameters and calculations, a noise-equivalent temperature difference (NETD)-based range optimization model for staring IRST systems is derived, offering a new solution method. Compared with traditional range models, the proposed model uses fewer parameters, fully considers the spectral radiation characteristics of the object and background and separately fits the integral part into a function related only to the range, which simplifies calculation and improves accuracy. The proposed operating range model is applied to a flying object for sample calculation, and the accuracy of the model is verified by field experiments.