INTERFERENCE COORDINATION METHOD BASED ON GRAPH THEORY IN TWO-TIER CELLULAR NETWORKS

This paper studies an interference coordination method by means of spectrum allocation in Long-Term Evolution (LTE) multi-cell scenario that comprises of macrocells and femtocells. The purpose is to maximize the total throughput of femtocells while ensuring the Signal-to-Interference plus Noise Ratio (SINR) of the edge macro mobile stations (mMSs) and the edge femtocell Mobile Stations (fMSs). A new spectrum allocation algorithm based on graph theory is proposed to reduce the interference. Firstly, the ratio of Resource Blocks (RBs) that mMSs occupy is obtained by genetic algorithm. Then, after considering the impact of the macro Base Stations (mBSs) and small scale fading to the fMS on different RBs, multi-interference graphs are established and the spectrum is allocated dynamically. The simulation results show that the proposed algorithm can meet the Quality of Service (QoS) requirements of the mMSs. It can strike a balance between the edge fMSs' throughput and the whole fMSs' throughput.

Second-order interference of two independent and tunable single-mode continuous-wave lasers

The second-order temporal interference of two independent single-mode continuous-wave lasers is discussed by em- ploying two-photon interference in Feynman＇s path integral theory. It is concluded that whether the second-order temporal interference pattern can or cannot be retrieved via two-photon coincidence counting rate is dependent on the resolution time of the detection system and the frequency difference between these two lasers. Two identical and tunable single-mode continuous-wave diode lasers are employed to verify the predictions. These studies are helpful to understand the physics of two-photon interference with photons of different spectra.

Impact of the spatial coherence on self-interference digital holography

Owing to the unique feature that the signal and reference waves of self-interference digital holography(SIDH)contain the same spatial information from the same point of object,compared with conventional digital holography,the SIDH has the special spatial coherence properties.We present a statistical optics approach to analyzing the formation of cross-correlation image in SIDH.Our study reveals that the spatial coherence of illumination light can greatly influence the imaging characteristics of SIDH,and the impact extent of the spatial coherence depends substantially on the recording distance of hologram.The theoretical conclusions are supported well by numerical simulation and optical experiments.

A Game Theoretic Approach for Inter-Network Interference Mitigation in Wireless Body Area Networks

Wireless Body Area Network(WBAN) is an emerging technology to provide real-time health monitoring and ubiquitous healthcare services. In many applications, multiple wireless body area networks have to coexist in a small area, resulting in serious inter-network interference. This not only reduces network reliability that is especially important in emergency medical applications, but also consumes more power of WBANs. In this paper, an inter-network interference mitigation approach based on a power control algorithm is proposed. Power control is modeled as a non-cooperative game, in which both inter-network interference and energy efficiency of WBANs are considered. The existence and uniqueness of Nash Equilibrium in the game are proved, and an optimal scheme based on best response is proposed to find its Nash Equilibrium. By coordinating the transmission power levels among networks under interference environment, the total system throughput can be increased with minimum power consumed. The effectiveness of the proposed method has been illustrated by simulation results, where the performance of the proposed approach is evaluated in terms of overall utility and power efficiency and convergence speed.

Second-order interference of two independent photons with different spectra

The second-order interference of two independent photons with different spectra in a Shih-Alley/Hong-Ou-Mandel interferometer is studied in Feynman's path integral theory. There is a second-order interference pattern for photons with different spectra if the photons are indistinguishable for the employed detection system. The conditions to observe the second-order temporal beating with photons of different spectra are analyzed. The influence of the response time of the detection system on the observed second-order interference pattern is also discussed. It is a direct result of that measurement in quantum mechanics is dependent on the employed measuring apparatus. The results are helpful to understand the physics of two-photon interference in different schemes.

Temporal interference driven by an oscillating electric field in photodetachment of H^- ion

The real time domain interferometry for the photodetachment dynamics driven by the oscillating electric field has been studied for the first time. Both the geometry of the detached electron trajectories and the electron probability density are shown to be different from those in the photodetachment dynamics in a static electric field. The influence of the oscillating electric field on the detached electron leads to a surprisingly intricate shape of the electron waves, and multiple interfering trajectories generate complex interference patterns in the electron probability density. Using the semiclassical open-orbit theory, we calculate the interference patterns in the time-dependent electron probability density for different electric field strengths, different frequencies and phases in the oscillating electric field. This method is universal, and can be extended to study the photoionization dynamics of the atoms in the time-dependent electric field. Our study can guide the future experimental researches in the photodetachment or photoionization microscopy of negative ions and atoms in the oscillating electric field.

Second-order temporal interference of two independent light beams at an asymmetrical beam splitter

The second-order temporal interference of classical and nonclassical light at an asymmetrical beam splitter is discussed based on two-photon interference in Feynman＇s path integral theory. The visibility of the second-order interference pattern is determined by the properties of the superposed light beams, the ratio between the intensities of these two light beams, and the reflectivity of the asymmetrical beam splitter. Some requirements about the asymmetrical beam splitter have to be satisfied in order to ensure that the visibility of the second-order interference pattern of nonclassical light beams exceeds the classical limit. The visibility of the second-order interference pattern of photons emitted by two independent single-photon sources is independent of the ratio between the intensities. These conclusions are important for the researches and applications in quantum optics and quantum information when an asymmetrical beam splitter is employed.

Channel Assignment Method Using Parallel Tabu Search Based on Graph Theory in Wireless Sensor Networks

Wireless sensor networks are suffering from serious frequency interference.In this paper,we propose a channel assignment algorithm based on graph theory in wireless sensor networks.We first model the conflict infection graph for channel assignment with the goal of global optimization minimizing the total interferences in wireless sensor networks.The channel assignment problem is equivalent to the generalized graph-coloring problem which is a NP-complete problem.We further present a meta-heuristic Wireless Sensor Network Parallel Tabu Search(WSN-PTS) algorithm,which can optimize global networks with small numbers of iterations.The results from a simulation experiment reveal that the novel algorithm can effectively solve the channel assignment problem.

Semi-classical theory and experimental research for polarization flipping in a single frequency laser with feedback effect

In this paper, we propose a semi-classical theory to successfully explain the polarization flipping in a single frequency laser. An experimental setup is built to verify this theory. The observed experimental phenomena are consistent with the theoretical analysis. We perform phase retardation measurements of birefringent components using this experimental system. The results show that the measurement repeatability is 0.12° and the measurement accuracy is 0.22°.

基于场景感知的访问控制模型

动态访问控制模型是构建大数据动态访问控制系统的理论基础,而现有访问控制模型大多只能满足单一情景下的动态访问控制,无法适应大数据上下文环境变化、实体关系变更和客体状态变迁等多类型动态情景中的访问控制。针对上述问题,在现有访问控制模型的研究的基础上,对大数据动态因素进行分析,提出基于场景感知的访问控制(SAAC,scenario-aware access control)模型。将各类型动态因素转换为属性、关系等基本元素;并引入场景信息对各类组成元素进行统一建模;基于场景信息构建大数据动态访问控制模型,以实现对多类型动态因素、扩展动态因素的支持。设计SAAC模型的工作框架,并提出框架工作流程对应的基于场景感知的访问控制模型规则学习算法和SAAC规则执行算法,以实现访问控制规则自动学习和动态访问控制决策。通过引入非传递无干扰理论,分析并验证了对所提模型的安全性。为验证所提模型访问控制策略挖掘方法的有效性,将SAAC模型与ABAC-L、PBAC-X、DTRM和FB-CAAC等基线模型在4个数据集上进行了实验对比。实验结果表明,SAAC模型及其策略挖掘方法的ROC曲线的线下面积、单调性和陡峭度等指标的结果均优于基线模型,验证了所提模型能够支持多类型动态因素和动态因素扩展,其挖掘算法所得的访问控制规则的综合质量相对较高。

需求变动视角下虚拟养老服务人员调度研究

针对虚拟养老服务人员实时调度问题,基于需求变动视角分别构建成本最优的调度优化模型和扰动最小的干扰管理模型,通过改进灰狼优化算法的位置更新公式,引入非支配排序设计多目标遗传灰狼优化算法。通过求解标准算例对比算法求解指标验证了算法的优越性,通过设计并求解算例验证模型的可行性。研究结果表明:相较于重调度法,干扰管理模型能够显著降低干扰事件对各主体的影响,生成更为丰富的决策集合,更加适合虚拟养老服务人员的调度问题。

局部鲁棒预处理的DME干扰抑制方法

全球定位系统(Global Positioning System, GPS) L5/北斗B2/Galilea E5是全球卫星导航系统(Global Navigation Satellite System, GNSS)的重要组成部分,为民用航空提供与生命安全相关的应用服务.然而L5/B2/E5信号处于受保护的航空无线电导航服务(Aeronautical Radio Navigation Service, ARNS)频段内(962~1213 MHz),同时工作在该频段内的还有民用航空导航系统测距机(Distance Measuring Equipment, DME)等. DME发射的大功率脉冲信号会对L5/B2/E5等卫星导航信号造成干扰,使得接收机无法正常捕获卫星信号或导致跟踪环路失锁.传统的DME干扰抑制方法通过在干扰稀疏域,如时域、频域和时频混合域进行DME干扰置零,这会在抑制干扰的同时完全消除与干扰重叠的卫星信号.为了降低DME干扰抑制对卫星信号的损失,本文提出基于鲁棒统计理论的局部鲁棒预处理的DME干扰抑制方法,根据DME干扰所在的稀疏域特性提取出存在干扰的信号片段后,应用非高斯分布下的鲁棒统计理论对提取出的数据样本进行鲁棒预处理,从而在抑制干扰的同时降低对卫星信号的影响.实验结果表明本文所提出的稀疏域局部鲁棒预处理的DME干扰抑制方法的性能优于相应的传统稀疏域方法,输出捕获因子比传统稀疏域方法提高1~2 dB.

草地植物生殖分配研究进展

植物生殖分配调控着植物营养生长与生殖生长的平衡,从而影响种群的更新速度,最终改变群落结构及演替方向。因此,研究植物生殖分配对草地生态系统稳定和可持续发展至关重要。本文通过文献综述方法,系统地梳理了草地生态系统植物生殖分配的相关研究理论及影响因素,学者们先后基于最优控制理论、生活史理论和生物量分配理论提出光合补偿机制、养分循环假说、时间限制假说、r/k策略、资源可用性假说等,以解释自然环境因素、植物自身因素和人为干扰因素等调控植物生殖分配的机制。然而,草地植物对诸多因素(植株形态性状、自然灾害、放牧、刈割、外源养分添加等)的生殖分配响应仍存在争议,且复杂因素(气候变化、生境条件、植物间竞争等)及多因素协作的过程和驱动机制不清晰。基于此,建议从多维度解析草地植物生殖分配策略及驱动机制,以期为促进草地生态系统更新及正向演替、提高草地资源利用率的研究提供理论依据。

Multicell power allocation method based on game theory for inter-cell interference coordination

As a new technology, coordinated multipoint （CoMP） transmission is included in LTE-Advanced study item. Moreover, the network architecture in LTE-Advanced system is modified to take into account coordinated transmission. Under this background, a novel power allocation game model is established to mitigate inter-cell interference with cellular coordination. In the light of cellular cooperation relationship and centralized control in eNodeB, the power allocation in each served antenna unit aims to make signal to interference plus noise ratio （SINR） balanced among inter-cells. Through the proposed power allocation game algorithm, the users＇ SINR can reach the Nash equilibrium, making it feasible to reduce the co-frequency interference by decreasing the transmitted power. Numerical results show that the proposed power allocation algorithm improves the throughput both in cell-center and cell-edge. Moreover, the blocking rate in cell-edge is reduced too.

N,B原子取代调控M-OPE分子器件的量子干涉与自旋输运

采用第一性原理计算基础上结合非平衡格林函数方法,开展了N,B原子取代对间苯乙烯低聚物(M-OPE)分子器件量子干涉与自旋输运的调控研究.研究结果表明N,B原子在中心苯环不同位置取代对M-OPE分子器件原有的相消量子干涉抑制程度不同.因此,N,B原子在不同位置取代后的器件电导存在较大差异研究还发现B原子取代的器件自旋电流值要明显高于N原子取代的器件,且B原子在特定位置取代后,器件在负偏压下的自旋电流值要明显大于正偏压下的自旋电流值,呈现显著的自旋整流效应.本文得到的N,B原子取代对分子体系量子干涉和自旋输运调控的物理机制,可以为杂环芳烃在分子电子学中的进一步应用提供理论指导.

面向重大活动电磁安全管控的协同电磁压制方法

该文研究了复杂环境条件下重大活动安保区域的电磁安全协同压制技术问题。首先采用了城市环境电波传播模型,建模分析了城市复杂电磁环境的特征。其次,针对高效电磁压制与有效避免有害干扰问题,利用势博弈方法设计电磁压制设备协同部署算法,基于此,提出了基于遗传算法的压制设备功率优化方法,实现了电磁压制设备协同工作下干扰功率的高效投送。仿真结果表明,所提出的电磁压制设备位置部署算法可获得与理论最优方法(即遍历算法)近似的优异性能,且运算复杂度更低;在保证相同干扰效果下,所提功率优化算法相较于传统干扰功率分配方法的传输功率降低了50%以上,实现了精准协同管控。

过盈连接结构优化设计探讨

过盈连接结构简单、定心精度高、可承受轴力扭矩等载荷,可靠性高,广泛应用于机械行业各领域。研究过盈连接设计理论和优化设计方法,对实际工程问题具有一定的指导作用。本文基于厚壁圆筒理论,分析了弹性和弹塑性状态下结合面压力、应力和过盈量之间的关系;然后基于上述分析结论,在弹性范围内,对几种过盈连接结构优化设计问题进行了探讨,提出了几种优化设计方法。通过优化设计,可以提高过盈连接中的结合面压力,提高连接强度,合理分配过盈连接结构结构参数,进而提高过盈连接的性能,满足实际工程应用中的要求。

电磁屏蔽高分子复合材料研究进展

系统综述了电磁屏蔽理论及影响因素,总结了电磁屏蔽高分子复合材料的研究进展,并对其发展趋势进行了展望。

电磁干扰环境MOS器件可靠性表征方法研究

工业芯片MOS器件的可靠性表征通常基于恒压应力或梯度应力方法对器件进行加速实验测试,根据测试结果对器件进行寿命评估。由于加速实验测试条件较为单一,难以覆盖工业芯片常见电磁干扰应用环境,MOS器件实际应用场景退化程度不能根据此方法进行有效界定,进而影响对工业芯片工作稳定性的精准判断。本研究提出一种微观层面MOS器件寿命评估方法,结合TCAD仿真软件对电磁干扰环境MOS器件寿命进行预测。该方法有效避免了电磁干扰环境器件输出波动带来的错误反馈,对器件寿命的预测具备一定保守性,能较大限度保证芯片在电磁环境中的正常运作。

新媒体背景下思想政治教学信息干扰:模型、类型及管控

思政课教学的本质是思想政治教学信息的传输。本研究以“申农-韦弗通信模型”为基础,探索得知新媒体背景下思想政治教学信息干扰模型已从传统“双主体”模型变为暂时性的“多主体”模型。借鉴信息传播学理论,新媒体背景下思想政治教学干扰可分为相对干扰和绝对干扰两大类型,相对干扰又可以分为思想政治教学信息主体编译目的迥异形成的干扰、思想政治教学信息主体编译能力差异形成的干扰和思想政治教学信息通道堵塞形成的干扰;绝对干扰可分为思想政治教学信息通道被污染形成的干扰和受众被不良信息蒙蔽形成的干扰。新媒体环境下思政课教学中的信息干扰具有必然性,不可能完全消除,可以通过提升思想政治教学信息传输主体素养、优化思想政治教学信息传输环境、提升思政课教师信息编译码能力、建立协同共享信息整合平台等策略进行管控,将新媒体技术转化为思想政治教学信息有效传输的最大“增量”。