基于误差估值累加开环校正的诱导式欺骗检测方法

诱导式卫星欺骗干扰可诱导航空器逐渐偏离预定航迹，难以被发现，因此及时有效地检测干扰是飞行安全的保障。在现有紧组合导航体制基础上，设计了一种基于误差估值累加开环校正的紧组合导航结构，并证明了其性能与传统闭环校正紧组合导航性能等效。在此结构中，将紧组合导航系统与自适应序贯概率比检测方法结合，提出了一种基于误差估值累加开环校正的诱导式欺骗检测方法，融合紧组合导航信息与其他不受欺骗影响的导航信息，构建欺骗检测统计量进行诱导式欺骗检测。仿真结果表明，开环校正结构可避免随时间累加的惯性导航系统误差所导致的组合导航滤波器发散问题，同时欺骗检测方法可进一步提高算法对“最坏”情形下微小诱导式欺骗的检测效果。     

On the effects of the packet size distribution on the packet loss process

Real-time multimedia applications have to use forward error correction (FEC) anderror concealment techniques to cope with losses in today’s best-effort Internet. The efficiency of these solutions is known however to depend on the correlation between losses in the media stream. In this paper we investigate how the packet size distribution affects the packet loss process, that is, the distribution of the number of lost packets in a block, the related FEC performance and the average loss run length. We present mathematical models for the loss process of the MMPP+M/D/1/K and the MMPP+M/M/1/K queues; we validate the models via simulations, and compare the results to simulation results with an MPEG-4 coded video trace. We conclude that the deterministic packet size distribution (PSD) not only results in lower stationary loss probability than the exponential one, but also gives a less correlated loss process, both at a particular average link load and at a particular stationary loss probability as seen by the media stream.Our results show that for applications that can only measure the packet loss probability, the effects of the PSD on FEC performance are higher in access networks, where a single multimedia stream might affect the multiplexing behavior. Our results show that the effects of the PSD on FEC performance are higher in access networks, where a single multimedia stream might affect the multiplexing behavior and thus can improve the queuing performance by decreasing the variance of its PSD.     

纵向泵浦Cr∶ Nd∶GSGG激光棒的热透镜效应研究

对纵向泵浦Cr∶Nd∶GSGG激光棒的热透镜效应进行了详细的理论分析。对温度分布的函数表达式 ,进行了讨论 ;分析了热引起的应力 ,得到了激光棒破裂的临界功率公式 ;最后对光学畸变进行了分析与讨论 ,推导了光程差计算公式     

双贴合无光焦度校正板在主反射镜前的两镜系统的像差特性

在光学系统中特别是反射系统中经常通过加无光焦度校正板来减少或消除其他元件所产生的像差。讨论了双贴合无光焦度校正板放在主镜前的双反射球面系统，根据像差理论分析了消像差的条件，研究了系统中各种参数的变化对系统高级残余像差的影响。结果表明主镜的相对孔径越大，系统的残余像差增加；正透镜在前的校正板结构优于负透镜在前的结构；选择合适的校正板单透镜的光焦度，可使系统的高级残余像差最小。     

带通采样在数据采集中的应用研究

在数据采集中采用带通采样，可大大降低采样率，但系统中的抗混叠滤波器会造成相位的非线性。采用对滤波后的信号进行带通采样，然后再用FRR滤波器校正相位的非线性，从而不失真地还原原信号，最后在Matlab中进行仿真，验证了该方法的有效性。     

一种零电压转换有源功率因数校正电路的研究

提出了一种基于UC3854的零电压转换有源功率因数校正(ZVT-APFC)的控制电路实现方案,介绍了ZVT电路工作原理,着重分析了由分立元件构成的辅助开关管的驱动电路,通过实验证实了驱动电路的稳定性和可靠性,并通过效率比较验证了ZVT-APFC电路的优良性能。与采用UC3855的电路相比,该电路方案具有简单、可靠、成本低等优点。     

Effect of absorbed pump power on the quality of output beam from monolithic microchip lasers

The dependence of the beam propagation factor (M ² parameter) with the absorbed pump power in the case of monolithic microchip laser under face-cooled configuration is extensively studied. Our investigations show that the M ₂ parameter is related to the absorbed pump power through two parameters (α and β) whose values depend on the laser material properties and laser configuration. We have shown that one parameter arises due to the oscillation of higher order modes in the microchip cavity and the other parameter accounts for the spherical aberration associated with the thermal lens induced by the pump beam. Such dependency of M ² parameter with the absorbed pump power is experimentally verified for a face-cooled monolithic microchip laser based on Nd³⁺ -doped GdVO₄ crystal and the values of α and β parameters were estimated from the experimentally measured data points.     

基于规则的光学邻近矫正中规则的相关处理

讨论了如何选择适当的规则,如何建立简洁实用的规则库,如何应用规则库.提出了四种主要的光学邻近矫正规则,在实验结果中列举了规则库中的部分数据.利用规则矫正后的版图光刻得到的硅片图形有了明显的改善.规则库的自动建立部分 (OPCL)是基于规则的光学邻近矫正系统的重要组成部分.     

(Anti-)de Sitter Black Hole Entropy and Generalized Uncertainty Principle

We generalize the method that is used to study corrections to Cardy-Verlinde formula due to generalized uncertainty principle and discuss corrections to Cardy-Verlinde formula due to generalized uncertainty principle in (anti)-de Sitter space. Because in de Sitter black hole spacetime the radiation temperature of the black hole horizon is different from the one of the cosmological horizon, this spacetime is a thermodynamical non-equilibrium spacetime.     

250W带功率因数校正整流电源模块的研制

功率因数校正技术越来越成为电源行业研究的热点。文中介绍了适用于雷达等设备的250W带功率因数校正整流电源模块的设计，分析了其中升压电感器设计、主开关管保护、控制电路消振、散热设计和表面贴装等关键技术，完成了实验研究，获得了满意的试验结果。