Networks, Fields and Organizations: Micro-Dynamics, Scale and Cohesive Embeddings

Social action is situated in fields that are simultaneously composed of interpersonal ties and relations among organizations, which are both usefully characterized as social networks. We introduce a novel approach to distinguishing different network macro-structures in terms of cohesive subsets and their overlaps. We develop a vocabulary that relates different forms of network cohesion to field properties as opposed to organizational constraints on ties and structures. We illustrate differences in probabilistic attachment processes in network evolution that link on the one hand to organizational constraints versus field properties and to cohesive network topologies on the other. This allows us to identify a set of important new micro-macro linkages between local behavior in networks and global network properties. The analytic strategy thus puts in place a methodology for Predictive Social Cohesion theory to be developed and tested in the context of informal and formal organizations and organizational fields. We also show how organizations and fields combine at different scales of cohesive depth and cohesive breadth. Operational measures and results are illustrated for three organizational examples, and analysis of these cases suggests that different structures of cohesive subsets and overlaps may be predictive in organizational contexts and similarly for the larger fields in which they are embedded. Useful predictions may also be based on feedback from level of cohesion in the larger field back to organizations, conditioned on the level of multiconnectivity to the field.     

7.13 W全固态1 319 nm宏微脉冲激光器

研制了一台高效率全固态平均功率7.13 W的1 319 nm宏微脉冲激光器。激光器采用热稳Z形折叠腔,增益模块采用自行研制的准连续15个二极管芯片环形泵浦的Nd:YAG模块,采用主动声光锁模器作为锁模元件,并在腔内插入倍频KTP晶体对激光器的输出尖峰进行抑制。为了获得稳定的锁模状态,对激光器腔长进行了精确设计和调节。当激光器腔长与锁模器驱动频率匹配时,获取了宏脉冲重复频率400 Hz、脉宽约190 μs,微脉冲重复频率95.6 MHz、脉宽小于1.0 ns的1 319 nm激光脉冲。     

宏微协同组网下基于小区分簇的联合传输与无线资源分配

针对宏微协同组网下小区间无线资源管理问题,文章提出一种大规模多入多出系统下基于微小区分簇的联合传输和动态频谱分配策略,该策略分两步执行以优化网络加权和速率.首先,所提算法根据各用户当前的信道状态执行微小区分簇,以尽可能地降低小区间干扰,提升系统容量.接着,宏基站和各微小区簇根据所服务用户当前的业务请求信息分别为其动态分配子载波,以最大化网络加权和速率,并提升资源利用率.仿真结果显示,该文提出的微小区分簇和动态频谱分配策略能在尽可能降低宏微协同组网中用户间干扰的同时,有效地提升系统吞吐量.     

Modeling Dual-Drive Gantry Stages with Heavy-Load and Optimal Synchronous Controls with Force-Feed-Forward Decoupling

The application of precision dual-drive gantry stages in intelligent manufacturing is increasing. However, the loads of dual drive motors can be severely inconsistent due to the movement of heavy loads on the horizontal crossbeam, resulting in synchronization errors in the same direction movement of dual-drive motors. This phenomenon affects the machining accuracy of the gantry stage and is an critical problem that should be immediately solved. A novel optimal synchronization control algorithm based on model decoupling is proposed to solve the problem. First, an accurate physical model is established to obtain the essential characteristics of the heavy-load dual-drive gantry stage in which the rigid-flexible coupling dynamic is considered. It includes the crossbeam’s linear motion and rotational motion of the non-constant moment of inertia. The established model is verified by using the actual system. By defining the virtual centroid of the crossbeam, the cross-coupling force between dual-drive motors is quantified. Then, the virtual-centroid-based Gantry Synchronization Linear Quadratic Regulator (GSLQR) optimal control and force-Feed-Forward (FF) decoupling control algorithm is proposed. The result of the comparative experiment shows the effectiveness and superiority of the proposed algorithm.     

TFT-LCD检测中基于激光三角法的显微镜离焦快速在线检测及补偿

光学成像检测设备的快速自动对焦是基于机器视觉快速缺陷检测的关键,为了解决检测过程中不同倍数物镜景深(0.5~91μm)跨度大以及被检测物体振动给快速对焦造成的影响等问题,提出了基于激光三角法的显微镜离焦在线检测及补偿方法。该方法利用激光三角法进行离焦量和离焦方向的快速探测,使用由行程100μm的压电陶瓷和行程25 mm直流电机构成的宏微双驱动结构协同控制完成大范围对焦任务。实验结果表明,构建的宏微结构对焦方式可以在0.4 s内实现高倍物镜±0.5μm景深至低倍物镜±91μm景深大范围的快速自动对焦,并实现被检测物体±3μm振动范围的快速自动跟随对焦。该方法满足了新一代薄膜场效应晶体管液晶显示器(TFT-LCD)工业检测装备对自动化对焦范围、速度和精度的要求,同时可应用在平板显示器(FPD)检测、线路板检测、生物医学和自动机器装配等领域。     

宏-微脉冲激光激发钠信标回波光子数的数值计算与探讨

当采用低功率的宏-微脉冲激光激发钠信标时, 尽管激光传输和钠信标光斑大小受到大气湍流影响, 但是钠信标具有回波光子数无起伏且激发品质因数高的优点. 除此之外, 宏-微脉冲激光激发钠信标还与激光的宏脉冲线型有关. 对于高斯线型的宏脉冲, 增大微脉冲的宽度有利于提高激发钠信标的品质因数和激发态概率. 为了获得更多的钠信标回波光子和较小的钠信标半径, 增大激光功率的同时要考虑良好的光束质量、适当的激光发射口径以及光谱宽度等影响因素. 因此, 优选宏-微脉冲激光的参数、发射口径、发射方式等对于激发优良特性的钠信标有着重要的现实意义.     

光学体系宏观-微观纠缠及其在量子密钥分配中的应用

宏观-微观纠缠最早起源于“薛定谔的猫”思想实验, 是指在宏观体系与微观体系之间建立量子纠缠. 实现宏观-微观纠缠可以利用多种物理体系来完成, 本文重点介绍了在光学体系中制备和检验宏观-微观纠缠的发展过程. 从最初的受激辐射单光子量子克隆到光学参量放大, 再到相空间的位移操作, 实验上制备宏观-微观纠缠的方法取得了长足的进步. 利用非线性光学参量放大过程制备的宏观-微观纠缠的光子数可以达到10⁴量级, 人眼已经可以观察到, 因此使用人眼作为探测器来检验宏观-微观纠缠的实验开始出现. 但随后人们意识到, 粗精度的光子数探测器, 例如人眼, 无法严格判定宏观-微观纠缠的存在. 为了解决这个难题, 提出了一种巧妙的方法, 即在制备宏-微观纠缠后, 利用局域操作过程将宏观态再变为微观态, 通过判定微观纠缠存在的方法来判定宏微观纠缠的存在. 之后相空间的位移操作方法将宏观态的粒子数提高到10⁸, 并且实现了纠缠的严格检验. 利用光机械实现宏观-微观纠缠的方案也被提出. 由于量子密钥分配中纠缠是必要条件, 而宏观-微观纠缠态光子数较多这一优势可能会对量子密钥分配的传输距离有所提高. 本文介绍了利用相位纠缠的相干态来进行量子秘钥分配的方案, 探讨了利用宏观-微观纠缠实现量子密钥分配的可能性.     

Performance Analysis of Duty-Cycle Division Multiplexing over Wavelength Division Multiplexing System

Abstract

Performance optimization of a duty-cycle division multiplexing system over 8- and 40-channel wavelength division multiplexing networks is reported in this article. The modified duty-cycle division multiplexing system with optical domain multiplexing using a dual-drive Mach–Zehnder modulator is simulated with two and three users per wavelength. Using conventional dispersion compensation, the 40 × 40-Gbps system with two and three users per channel can support 240 and 160 km of transmission distance, respectively. The dispersion management technique based on a chirped fiber Bragg grating is proposed for a 40 × 3 × 13.33-Gbps duty-cycle division multiplexing/wavelength division multiplexing system that allows double the transmission distance compared to conventional technique.     

基于可变激光源和啁啾M-Z调制器的双调谐光电振荡器

设计了一种利用微波光子滤波器(MPF)实现频率可调谐的光电振荡器(OEO)。该模型通过双驱动Mach-Zehnder调制器(DD-MZM)和啁啾光栅形成高Q值的MPF,得出OEO的振荡频率是关于光源波长和DD-MZM直流偏置电压的函数,通过对光源波长或DD-MZM偏置电压的调整,可实现振荡频率调谐功能。同时,在电域上,利用RF耦合器和RF延时线形成两路具有延时差的反馈信号,通过合并后反馈至DD-MZM,从而有效地抑制边模。理论和仿真实验表明,针对不同的调谐范围可实现粗调和微调的功能。     

STUDY ON THE PARAMETER VALUE DOMAIN OF MACRO-MICRO CONSTITUTIVE MODEL

宏微观耦合本构模型的参数识别往往通过反分析方法进行,为了使参数识别结果具有高的置信度,需要确定合适的参数取值范围. 基于动态再结晶过程的微观机理以及相应本构方程的数学特征,提出一个确定参数取值范围的方法. 首先详细给出考虑动态再结晶的黏塑性本构模型,并根据模型构造物理机理,提出通过6 步确定该模型参数取值范围的方法;其次,对300M 低合金钢进行不同温度、应变速率下的热变形试验,测试宏观的流动应力-应变数据及微观的组织数据;然后应用提出的方法,依据试验数据,确定参数取值范围;最后,基于确定参数取值范围中获得的知识,对模型进行局部修改,使模型模拟结果更接近实验结果.