一种自动跟踪工频陷波器的研究与设计

介绍了一种新型线性自动跟踪工频陷波器的电路结构。该陷波器应用于电子束曝光机束流测量电路中,用来抑制工频干扰对测量精度的影响。基于对自动跟踪陷波器的基本工作原理分析,陷波器采用了频率/电压转换器与压控带阻滤波器相结合的设计方案,成功地解决了工频频偏对常规工频陷波器滤波性能的严重影响问题。提出了提高抑制工频干扰能力的设计要点和电路调试方法。通过性能指标的测试和长期实际运行应用,证明陷波器满足了电子束测量中对工频干扰进行强抑制的要求,提高了电子束曝光机的制版质量。     

Measuring performance degradation of virtual machines based on the Bayesian network with hidden variables

In the virtualized environment, multiple virtual machines (VMs) sharing the same physical host are vulnerable to resource competition, which may cause performance interference among VMs and thus lead to VM performance degradation. This paper focuses on measuring CPU, memory, I/O, and the overall VM performance degradation caused by the performance interference according to the properties in the runtime environment of VMs. To this end, we adopt Bayesian network (BN), as the framework for uncertainty representation and inference, and construct a VM property‐performance BN (VPBN) with hidden variables, which represent the unobserved performance degradation of CPU, memory, and I/O, respectively. Then, we present the method to measure performance degradation of VMs by probabilistic inferences with the VPBN. Experimental results show the accuracy and efficiency of our method.     

红外源强度对激光干扰效应的影响

分析了红外目标源辐射强度随距离和时间的变化。在不同红外源强度的 条件下，进行了红外源强度对红外系统输出信号的响应定标。同时，在激光辐照功率67W和辐照时间460ms条件下，用1.06μm连续ND：AYG激光对不同红外源强度下红外系统输出信号的干扰效果进行了对比实验。结果表明：激光对红外系统的干扰效果与红外目标源的强度成正比。当红外源强度在红外系统工作的线性范围时，激光对红外系统的干扰效果最明显。     

On co-channel and adjacent channel interference mitigation in cognitive radio networks

Cognitive radio (CR) is an emerging wireless communications paradigm of sharing spectrum among licensed (or, primary) and unlicensed (or, CR) users. In CR networks, interference mitigation is crucial not only for primary user protection, but also for the quality of service of CR user themselves. In this paper, we consider the problem of interference mitigation via channel assignment and power allocation for CR users. A cross-layer optimization framework for minimizing both co-channel and adjacent channel interference is developed; the latter has been shown to have considerable impact in practical systems. Cooperative spectrum sensing, opportunistic spectrum access, channel assignment, and power allocation are considered in the problem formulation. We propose a reformulation–linearization technique (RLT) based centralized algorithm, as well as a distributed greedy algorithm that uses local information for near-optimal solutions. Both algorithms are evaluated with simulations and are shown quite effective for mitigating both types of interference and achieving high CR network capacity.     

基于TD-SCDMA的R4与HSDPA混合组网系统级性能研究

文章认为R4和高速下行数据接入(HSDPA)的混合组网方式是目前比较合理的组网方式,可以减少建设成本,并降低管理维护和优化的复杂度,是主流运营商倾向的组网方式。文章提出通过理论计算结合系统级仿真手段可以对基于TD-SCDMA的R4与HSDPA业务混合组网前后系统性能进行对比研究,并提出通过优化HSDPA业务信道发射功率、调度算法、无线资源管理(RRM)算法等多种手段可以提升混合组网后系统性能。     

光栅衍射缝间干涉因子次极大强度对称性的菲涅耳半波带法证明

本文用菲涅耳半波带法推导出了一个非常有用的次极大位置公式,将该位置公式和振幅矢量法求出的次极大位置结合起来,方便地求出了缝间干涉因子的次极大的强度,证明了缝向干涉因子的次极大强度具有对称性。避免了对振幅矢量法求次极大位置这个方程的直接求解,因为用该方法求出的次极大强度与理论值完全符合,说明菲涅耳半波带法不但可以用来分析单缝衍射,同时还完全能够用来分析光栅衍射。     

激光电源中印制电路板的抗干扰技术

论文分析了影响激光电源中印制电路板电磁兼容性能的主要因素,包括印制电路板（PCB）导线阻抗、元器件布局以及与外界的连接等;提出了相应的解决措施,并通过试验实例加以说明。     

电力线载波通信EMI滤波电路研究

电力线通信是一个正在发展的崭新学科,但由于电力线传输的无屏蔽性,给电力线通信带来严重的电磁干扰与电磁兼容问题。在深入分析了电力线通信系统产生电磁干扰的主要原因的基础上,对EMI滤波电路进行了设计研究,并通过实验验证了该滤波网络对于抑制电力线载波通信EMI的可行性。     

磁保持继电器空间磁干扰敏感位置的研究

开关器件的快速动作具有较高的du/dt与di/dt,使其本身成为干扰源对周围设备产生电磁干扰,文章以外加磁钢模拟磁保持继电器上方可能存在的干扰源,运用有限元分析软件建立其静态干扰模型.基于不同位置外部磁钢对衔铁组件所受力矩的影响具有极大值,将黄金分割法应用于对磁保持继电器空间磁干扰敏感位置的求解.结果表明,与衔铁组件平行的磁场方向为磁干扰敏感方向,敏感方向下存在磁干扰最大位置即敏感位置.此外,进一步确定了空间磁干扰危险区间.     

Time delay estimation algorithm of narrow band internet of things based on inter-cell interference cancellation

Aiming at the characteristics of NB-IoT such as low power consumption,low cost and low sampling rate,an NB-IoT delay estimation algorithm based on inter-cell interference cancellation was proposed.To gradually eliminate the interaction between signals in each cell,an inter-cell iterative interference cancellation algorithm was considered.In each iteration,the idea of time-frequency cross-correlation overlapping was introduced on the basis of traditional correlation algorithms to break through the limitations of the sampling rate and further improve the accuracy of time delay estimation.At the same time,a first-arrival-path (FAP) searching algorithm based on noise threshold was used to suppress multipath effects.Through experimental simulation,the results show that the proposed algorithm can significantly improve the time delay estimation accuracy of NB-IoT on the basis of related algorithms.