Effects of cross-Kerr coupling on transmission spectrum of double-cavity optomechanical system

We theoretically study the transmission spectrum of the cavity field in a double-cavity optomechanical system with cross-Kerr(CK) effect. The system consists of two tunneling coupling optomechanical cavities with a mechanical resonator as a coupling interface. By doping CK medium into the mechanical resonator, CK couplings between the cavity fields and the mechanical resonator are introduced. We investigate the effects of CK coupling strength on the transmission spectrum of the cavity field, including the transmission rate, nonreciprocity and four-wave mixing(FWM). We find that the transmission spectrum of the probe field can show two obvious transparent windows, which can be widened by increasing the CK coupling strength. For the transmission between the two cavity fields, the perfect nonreciprocity and reciprocity are present and modulated by CK coupling and phase difference between two effective optomechanical couplings. In addition, the effects of the optomechanical and CK couplings on FWM show that the single peak of FWM is split into three symmetrical peaks due to the introduction of the CK effect.

Analysis of Mixed Model in Gear Transmission Based on ADAMS

The traditional method of mechanical gear driving simulation includes gear pair method and solid to solid contact method. The former has higher solving efficiency but lower results accuracy; the latter usually obtains higher precision of results while the calculation process is complex, also it is not easy to converge. Currently, most of the researches are focused on the description of geometric models and the definition of boundary conditions. However, none of them can solve the problems fundamentally. To improve the simulation efficiency while ensure the results with high accuracy, a mixed model method which uses gear tooth profiles to take the place of the solid gear to simulate gear movement is presented under these circumstances. In the process of modeling, build the solid models of the mechanism in the SolidWorks firstly; Then collect the point coordinates of outline curves of the gear using SolidWorks API and create fit curves in Adams based on the point coordinates; Next, adjust the position of those fitting curves according to the position of the contact area; Finally, define the loading conditions, boundary conditions and simulation parameters. The method provides gear shape information by tooth profile curves; simulates the mesh process through tooth profile curve to curve contact and offer mass as well as inertia data via solid gear models. This simulation process combines the two models to complete the gear driving analysis. In order to verify the validity of the method presented, both theoretical derivation and numerical simulation on a runaway escapement are conducted. The results show that the computational efficiency of the mixed model method is 1.4 times over the traditional method which contains solid to solid contact. Meanwhile, the simulation results are more closely to theoretical calculations. Consequently, mixed model method has a high application value regarding to the study of the dynamics of gear mechanism.

Accelerated solution of the transmission maintenance schedule problem:a Bayesian optimization approach

To maximize the maintenance willingness of the owner of transmission lines,this study presents a transmission maintenance scheduling model that considers the energy constraints of the power system and the security constraints of on-site maintenance operations.Considering the computational complexity of the mixed integer programming(MIP)problem,a machine learning(ML)approach is presented to solve the transmission maintenance scheduling model efficiently.The value of the branching score factor value is optimized by Bayesian optimization(BO)in the proposed algorithm,which plays an important role in the size of the branch-and-bound search tree in the solution process.The test case in a modified version of the IEEE 30-bus system shows that the proposed algorithm can not only reach the optimal solution but also improve the computational efficiency.

UNIQUENESS OF THE INVERSE TRANSMISSION SCATTERING WITH A CONDUCTIVE BOUNDARY CONDITION

This paper considers the inverse acoustic wave scattering by a bounded penetrable obstacle with a conductive boundary condition.We will show that the penetrable scatterer can be uniquely determined by its far-field pattern of the scattered field for all incident plane waves at a fixed wave number.In the first part of this paper,adequate preparations for the main uniqueness result are made.We establish the mixed reciprocity relation between the far-field pattern corresponding to point sources and the scattered field corresponding to plane waves.Then the well-posedness of a modified interior transmission problem is deeply investigated by the variational method.Finally,the a priori estimates of solutions to the general transmission problem with boundary data in L^(p)(δΩ)(1<p<2)are proven by the boundary integral equation method.In the second part of this paper,we give a novel proof on the uniqueness of the inverse conductive scattering problem.

HRTEM Study of Three New Regularly Mixed-layer Structures of B_8S_6 Type in Ca-RE Fluorocarbonate Minerals

The microstructural features of clacium rare earth(Ca RE) fluorocarbonate minerals from Southwest China were studied by using selected area electron diffraction(SAED) and high resolution transmission electron microscopy(HRTEM). Three new regularly mixed layer structures of B 8S 6 type with long period and different stacking sequence, i.e. B 8S 6 Ⅰ, B 8S 6 Ⅱ, and B 8S 6 Ⅲ, were found in the derived polycrystal of parisite, in which their structural symmetry, cell parameters, chemical formulas of crystal and stacking models of structural unit layer, etc. were determined. The results of this study also show that these new regularly mixed layer structrues were formed by order stacking unit layer of bastnaesite(B) and synchisite(S) in varying proportion along c axis. The observation under HRTEM reveals that in the three new regularly mixed layer structures there are different distribution modes of Ce F ion layers, CO 2- 3 ion groups between the Ce F ion layers, and CO 2- 3 ion groups between Ce F and Ca 2+ ion layers, and there are some heterogeneous textures, such as disorder interlayer and stacking fault. It further proves the complexity of the crystal structure of the Ca RE fluorocarbonate minerals.

Illite-smectite Mixed-layer Minerals in the Alteration Volcanic Ashes under Submarine Environment

The clay mineralogy of the clay intervals interbedded with siliceous mudstones across the Permian-Triassic boundary (PTB) in Pengda, Guiyang, Guizhou province, was investigated by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The clay mineral assemblages of the sediments are mainly I/S clays and minor smectite, kaolinite, and illite as reveled by XRD analyses. The peak-shape parameters BB1 and BB2 of I/S clays of the representative clay bed PL-01 are 4.7° and 4.4°, and the peak position of the low angle reflection is at 6.8° 2θ (13.6 ), suggesting that the I/S clays has a IS type of ordering. However, the presence of multi-order reflections and their intensities are different from those of completely ordered 1∶1 mixed-layer I/S clay rectorite, indicating that I/S clays of the Pengda section have partially ordered IS structures. HRTEM observations show that most of the I/S clays exhibit an IS stacking ordering. However, in some areas within a IS particle, smectite layer is observed in doublets, triplets, and quartets, which are interstratified by various amounts of illite layers, suggesting the presence of other irregular stacking in addition to the major 1∶1 IS ordered stacking. Transformation of smectite layer into illite layers is also observed in the I/S clays, suggesting that the Pengda I/S clays are derived from smectite illitization, in good agreement with the clay mineral assemblage. The I/S clays of the Pengda section contain up to 45% to 95% smectite layer, the notably higher contents of smectite layer relative to those of other PTB stratigraphic sets in south China can be attributed to difference in alteration and smectite illitization processes due to different sedimentary environments.

波流联合作用下掺氢输气海管泄漏扩散研究

由于氢气密度低,泄漏后的掺氢天然气在海洋波流作用下的浮升扩散行为有别于纯天然气,其泄漏扩散规律有待明晰。利用计算流体力学方法数值模拟了波流联合作用下掺氢输气海管泄漏扩散的过程,结果表明气体泄漏的过程可分为泄漏初期、向上浮升以及横向迁移3个阶段。当掺氢比φ_(H2)<50%时,氢气泡的运动轨迹受天然气泡的影响显著。气体浮升高度和扩散直径的变化与时间成正相关,且随着掺氢比的增大,泄漏气体到达液面所需的时间延长。天然气泡和氢气泡直径在上升的过程中都逐渐增大,两者的浮升速度随浮升高度的增加先增大后减小,天然气泡的浮升速度衰减更快。氢气泡直径随掺氢量的增加而增大,天然气泡直径随掺氢量的增大而减小,两者的上升速度随着掺氢量的增大都表现出先增大后减小的趋势,且氢气泡的上升速度大于天然气泡的上升速度。波长和海流流速越大,泄漏气体的扩散直径越大。

基于FSC和TCSC混合复用的交直流混联线路潜供电弧特性

为提高系统运行稳定性,高补偿度串补装置广泛投入使用,但线路故障后潜供电流存在高幅值的低频分量,潜供电弧难以自熄。针对此问题,基于交直流混联输电线路,研究了不同布置方式下串补度对潜供电流与恢复电压幅值影响,提出了一种固定串补(fixed series compensation,FSC)和可控串补(thyristor controlled series compensation,TCSC)混合复用抑制潜供电弧的方法。此外,为满足线路对高补偿度的需求,设计FSC和TCSC混合复用串补度最佳配置方案。结果表明,交直流混联线路采用串补度40%的双平台分散布置方式,潜供电流与恢复电压幅值达到最小,燃弧时间最短。高补偿度串补线路TCSC采用串补度10%、20%的配置方案更利于熄弧,提高重合闸成功率。

宽阻带高频率选择性的混合电磁耦合滤波器

在无线和移动通信系统中,需要具有高选择性和结构紧凑的微波滤波器来抑制谐波和杂散信号。提出了一种新颖的基于阶跃阻抗谐振器的二阶可控混合电磁耦合滤波器,该滤波器由两个四分之一波长的阶跃阻抗谐振器组成,混合电磁耦合中的电耦合和磁耦合分别通过低阻抗部分的叉指结构和高阻抗的传导针来控制。同时在馈线上加载两对对称开路短截线,可以产生额外的传输零点,以获得更好的频率选择性和高抑制度的宽阻带。设计并制作了一个滤波器样品,测试的回波损耗大于18 d B,插入损耗为0.6 d B,上阻带拓宽到三倍的中心频率处,整个阻带抑制度优于17 d B,测量和模拟结果吻合良好。

基于混频电源运行的模块化多电平矩阵式换流器阀段试验系统

模块化多电平矩阵式换流器(M^(3)C)是目前柔性低频输电系统完成频率变换的主要电力电子设备。M^(3)C包含9个桥臂,应用在高压大功率场合的串联模块数目众多,对其设备子模块的生产提出了特殊试验需求。在M^(3)C桥臂稳态电压和电流分析基础上,设计了一种应用于数个串联桥臂子模块(阀段)的对拖运行试验系统,可对其进行等效功率运行测试,以辅助M^(3)C设备的生产和出厂测试。提出了对拖试验系统的控制策略,搭建了由两组4个串联子模块构成的阀段对拖试验系统,进行了相关试验验证。试验结果表明,所提出的试验系统能够满足M^(3)C桥臂串联子模块的等效功率运行试验,并且对电源功率消耗要求不高。

TFD-YOLOv8:一种用于输电线路的异物检测方法

基于无人机航拍图像的异物检测是输电线路智能巡检中的重要环节。YOLO目标检测算法精度高、速度快,是目前的主流算法。但在进行输电线路异物检测时,由于异物目标尺度多变、特征不显著,易出现误检、漏检等问题,提出一种用于输电线路异物检测的YOLOv8模型(TFD-YOLOv8)。首先,在YOLOv8颈部网络构建双分支下采样模块,截留下采样过程中易丢失的尺度相关细节信息,实现语义信息和细节信息的高效融合,提升不同尺度特征图的信息一致性。然后,在主干网络插入混合增强注意力模块,同时提取图像的全局和局部特征,分别生成空间注意力和通道注意力,得到一个包含局部信息、全局信息、空间信息和通道信息的混合增强注意力,增强网络对目标关键特征的捕捉能力。实验结果表明,与基线模型相比,本文方法的平均检测精度提升了6.7%,准确率和召回率分别提升了12.9%和5.1%,与多个现有目标检测方法相比,该方法在检测精度和复杂度上均具有优势。

兼顾本地与直流受端电网调峰需求的水电站群短期优化调度模型

面对巨型水电站群高压直流送端电网和受端电网日益严峻的调峰压力,建立了一种兼顾本地与直流受端电网调峰需求的梯级水电站群短期优化调度模型。模型以多电网剩余负荷最大值最小为目标,考虑常规梯级水电站群水力、电力约束,以及复杂高压直流输电线路运行约束,并引入直流线路与水电站之间耦合运行约束。在模型求解阶段,引入辅助变量将目标函数、水电运行约束、直流运行约束线性化,并采用大M法对直流线路与水电站之间双向区间耦合约束进行线性化,将原模型转换为混合整数线性规划模型。以中国西南地区某巨型水电站群冬季和夏季典型日为实例研究,结果表明:送端电网负荷峰谷差降幅高达100%,受端电网负荷峰谷差降幅分别达28.1%和31.6%。所提模型能够利用高压直流输电线路共享水电灵活性,有效实现多电网调峰,并保证直流输电线路运行在安全区间,可以为巨型梯级水电站群短期多电网调峰提供参考和借鉴。

基于Benders分解的交直流混合输电网随机扩展规划方法

采用随机场景模拟法描述机组和输电线路随机停电事故、负荷预测误差,提出了一种基于Benders分解的交直流混合输电网随机扩展规划方法。首先建立以交直流输电线路投资成本、失负荷成本、系统运行成本等为综合成本目标,采用Benders分解,将交直流混合输电网混合整数线性规划模型分解为规划主问题和可靠性校验和经济调度的子问题迭代求解。在6节点系统和改进的IEEE-118节点系统算例仿真结果表明:与交流输电系统相比,扩建直流输电线路可以节省更多的成本,在选择交流/直流输电线路时,直流线路输送潮流的可控性以及经济性都可以减少失负荷。

Transmission matrices used in epidemiologic modelling

Mixing matrices are included in infectious disease models to reflect transmission opportunities between population strata.These matrices were originally constructed on the basis of theoretical considerations and most of the early work in this area originates from research on sexually transferred diseases in the 80s,in response to AIDS.Later work in the 90s populated these matrices on the basis of survey data gathered to capture transmission risks for respiratory diseases.We provide an overview of developments in the construction of matrices for capturing transmission opportunities in populations.Such transmission matrices are useful for epidemiologic modelling to capture within and between stratum transmission and can be informed from theoretical mixing assumptions,informed by empirical evidence gathered through investigation as well as generated on the basis of data.Links to summary measures and threshold conditions are also provided.

智能现场混装乳化炸药车研制及工程应用

在矿石开采过程中,爆破工序的作业效率和安全性对于智能矿山建设具有重要影响。为了提升工业炸药现场混装技术的自动化、机械化水平,设计了一款智能现场混装乳化炸药车(简称“智能混装车”),详细介绍了智能混装车的整车结构、工艺原理、关键技术以及现场使用流程,并进行了工程应用。研究表明:(1)智能混装车实现了自动寻孔、遥控对孔、智能装药、故障智能排查、数据远程管理等功能,提升了炸药现场混装技术的自动化、智能化水平;(2)实现了装药参数实时提取,装药密度智能调节,确保炸药密度与岩石破碎能量精准匹配,显著提高了炸药能量利用率;(3)总装药工效(每人每分钟装药量)是普通混装车的2倍,是人工装药的4.7~7.0倍,提高了工作效率,降低了人工成本,整个爆破区域装药人员仅需1人,降低了人员暴露在危险环境的可能性,实现了本质安全。研究成果成功实现了长距离、多方位、多场景露天爆破安全高效装药,有助于提升我国智能化装药技术水平。

考虑磨损故障的双渐开线齿轮传动系统动态特性研究

针对目前双渐开线齿轮(DIG)研究过程中齿廓磨损对双渐开线齿轮动态特性的影响问题,对考虑磨损故障的双渐开线齿轮传动系统动态特性进行了研究。首先,进行了双渐开线齿轮接触线长度与齿面载荷计算,考虑相对滑移距离,建立了等效接触模型;然后,进行了双渐开线齿轮齿面累积磨损量、齿轮齿面累积磨损深度的计算,建立了双渐开线齿轮啮合刚度计算模型,进行了磨损故障的双渐开线齿轮刚度的计算;最后,以一对双渐开线齿轮为研究对象,采用集中质量法建立了6自由度动力学模型,研究了齿面磨损对双渐开线齿轮动力学特性的影响。研究结果表明:在运行1×104次载荷循环后,混合弹流润滑状态下,双渐开线齿轮与普通渐开线齿轮(CIG)在节线附近齿根位置的最大累计磨损量差值为0.00207μm,且双渐开线齿轮节线靠近齿顶位置的磨损小于普通渐开线齿轮的磨损;双渐开线齿轮系统在磨损后振动加速度幅值小于普通渐开线斜齿轮的幅值。通过对不同磨损情况下的时域响应进行研究,发现磨损导致双渐开线齿轮传动系统的振动幅值增大。

改善同塔混压双回直流输电线路电磁环境研究

为了改善高压直流输电线路日益严重的电磁影响,提出混压双回直流输电线路布置的新方案。新方案线路布置通过改变极导线空间几何架构,重构极导线电晕后正负离子的空间分布状态来减弱直流输电线路对环境的电磁影响,研究其电磁环境具有重要意义。本文基于Kaptzov假设,运用COMSOL多物理场耦合计算了新方案和常规布置下直流线路的离子流浓度、合成电场、走廊宽度以及合成电场在不同风速下的变化。结果表明,选择合适的新布置方案可有效改善电磁环境影响,节约输电走廊资源。此外,新方案布置下直流线路特有的低值域不对称电磁环境具有优异的抗风性与稳定性。

油气混输管道在线腐蚀检测及安全评估

针对塔河油田单井管线油气混输介质长期停用存在腐蚀问题,通过腐蚀因素和腐蚀原因初步分析,认为该管道存在内腐蚀风险。通过采用在线腐蚀检测技术,对单井管线开展腐蚀检测及评价,通过现场对管道5个开挖探坑的检测,开挖检测部分的管道安全强度达到继续使用的等级。但是由于仅是局部探坑检测,不排除管道其他部位存在极严重腐蚀,建议对该管线进一步开展试压,通过试压确定管线的承压能力和排查薄弱点,为下一步开展腐蚀治理提供依据。

混合调制毫米波光纤网络通信安全双重聚类数据传输方法

在高效频谱混合调制毫米波光纤网络通信中,为了确保通信数据传输安全,提出双重聚类算法下毫米波光纤网络通信安全数据传输方法。构建混合调制毫米波光纤网络通信信道模型,结合调光控制和高效频谱数据传输的双重作用进行光纤网络通信信道均衡控制,采用电磁耦合调制方法建立光纤网络通信信道多径干扰抑制模型,引入载波调制信号实现对光纤网络通信数据的输出稳定性调节,根据光强扰动参量实现对毫米波光纤网络通信的高效频谱混合调制和解调处理,提取光纤网络通信安全数据的高频特征量,采用双重聚类算法实现对光纤网络通信数据的分块聚类处理,并实现对毫米波光纤网络通信的级联信道路径增益估计,根据参数估计结果结合信道调制和抗干扰设计实现对数据的安全传输。测试表明,该方法进行光纤网络通信数据传输的误码率为10^(-12),信噪比为49 dB,抗干扰能力较强,传输安全性和及时性较好。

电力通信网络混合传输信号分离序列流程仿真

在电力通信网络中,混合传输信号环境较为复杂,难以准确地分离出电力通信网络混合传输信号,其SNR值相对较低。为此,对电力通信网络混合传输信号分离序列流程进行仿真研究。调用观测信号模型观测实时活跃的网络混合传输信号状态,计算网络信号的射频长度。利用FastICA方法对网络混合传输信号进行射频调制,将调制处理的信号信息压缩,计算盲源信号点位的个数和独立信号分量。根据载波频率估计值得到电力通信网络混合传输信号序列,实现序列分离。实验结果表明,所研究方法能够准确地分离电力通信网络混合传输信号序列,且SNR值高达27.69,有效满足电力通信网络混合传输需求。