Energy-based analysis of frequency entrainment described by van der Pol and phase-locked loop equations

This paper analyzes frequency entrainment described by van der Pol and phase-locked loop (PLL) equations. The PLL equation represents the dynamics of a PLL circuit that appear in typical phase-locking phenomena. These two equations describe frequency entrainment by a periodic force. The entrainment originates from two different types of limit cycles: libration for the van der Pol equation and rotation for the PLL one. To explore the relationship between the geometry of limit cycles and the mechanism of entrainment, we investigate the entrainment using an energy balance relation. This relation is equivalent to the energy conservation law of dynamical systems with dissipation and input terms. We show response curves for the dc component, harmonic amplitude, phase difference, and energy supplied by a periodic force. The obtained curves indicate that the entrainments for the two equations have different features of supplied energy, and that the entrainment for the PLL equation possibly has the same mechanism as does the regulation of the phase difference for the van der Pol equation.     

Optimization analysis on the bandwidth algorithm for the phase-locked loop (PLL) in OTU

The bandwidth of phase-locked loop (PLL) in optical transponder unit (OTU) is affected by both the external input jitter and the internal phase noise jitter, so the selection for the bandwidth of the PLL has a contradiction and it is necessary that the bandwidth is optimally designed. Under the consideration of both the external input jitter and the internal phase noise, the bandwidth algorithm of the PLL is comprehensively analyzed, and the optimization algorithm of the bandwidth for the PLL of the OTU can be deduced and obtained through improving the former calculation and analytical methods. The optimal bandwidth of the PLL has been analyzed and obtained so as to ensure that the clock output of the OTU has a lower jitter noise. And then the optimization algorithm is applied in 2.5 Gbit/s and 10 Gbit/s OTU, the optimal parameters of the PLL and the output jitter value of the OTU have been acquired by taking the quantitative and qualitative analysis of the PLL parameters. The study shows the optimization algorithm is superior and feasible as well as it is better used in the OTU and plays an important part in the practical application.     

Signal design using nonlinear oscillators and evolutionary algorithms: application to phase-locked loop disruption

This work describes an approach for efficiently shaping the response characteristics of a fixed dynamical system by forcing with a designed input. We obtain improved inputs by using an evolutionary algorithm to search a space of possible waveforms generated by a set of nonlinear, ordinary differential equations (ODEs). Good solutions are those that result in a desired system response subject to some input efficiency constraint, such as signal power. In particular, we seek to find inputs that best disrupt a phase-locked loop (PLL). Three sets of nonlinear ODEs are investigated and found to have different disruption capabilities against a model PLL. These differences are explored and implications for their use as input signal models are discussed. The PLL was chosen here as an archetypal example but the approach has broad applicability to any input∕output system for which a desired input cannot be obtained analytically.     

Evaluation of Properties and Structural Transitions of Poly-L-lysine: Effects of pH and Temperature

Abstract

The structural response to temperature and pH changes of poly-l-lysine (PLL) has been studied by a variety of experimental methods including turbidimetry, dynamic light scattering, and Zeta potential analysis. The experimental results and the molecular dynamics simulations showed that the PLL structural transitions were a result of a competition between electrostatic repulsion, which promotes an extended state, and the hydrophobic effect, which favors a compact state. In fact, as the pH was decreased, the PLL conformation changed from α-helix to the random coil and the hydrophilic volume increases resulted in a transition to spherical micelles which then swelled due to charge-charge repulsions. Following a rise in temperature and/or at high pH, PLL undergoes the α-helix-to-β-sheet transition and reacted more rapidly to form hydrophobic aggregates.     

Regeneratively mode-locked fiber laser with a repetition rate stability of 4.9x10-15 using a hydrogen maser phase-locked loop

We demonstrate an ultrastable regeneratively mode-locked fiber laser that employs a phase-locked loop (PLL) circuit with a hydrogen maser. The stability for an integration time of 1s was 6.2x10(-13), which is 16 times better than that of a conventional PLL laser. For an integration time of 1000s, the stability reached as high as 4.9x10(-15). The repetition-rate stability was limited by the synthesizer used for the PLL operation, and there was no additional fluctuation induced by the laser operation.     

彩色图像实时采集的硬件设计

本文分析了不同图像信号源的特点,提出了彩色图像数据采集的硬件设计方案。论述了数字化参数的选择原则。较详细地分析了所设计的两种锁相环电路：以彩色同步为基准的单片锁相环和以行频ｆＨ 为基准的锁相环。两种锁相环产生的时钟信号分别适合于标准信号和非标准信号。最后简述了帧存贮体和接口设计。本文提出的实时采集方案具有硬件少、软件简单、调试容易等优点     

Noisy fringe pattern demodulation by an iterative phase locked loop

The phase locked loop (PLL) technique applied to demodulate two-dimensional carrier-frequency fringe patterns has been developed recently. Here we present an extension to the basic PLL scheme to demodulate noisy fringe patterns. This modified technique estimates the phase in the fringe pattern iteratively; that is, the first wavefront estimation is done using a flat reference phase and the second iteration takes the demodulated phase found in the first iteration as the new reference. The third demodulating iteration uses the second phase estimation as the reference and so on, until further changes in the detected wavefront fall below a predefined threshold. During the iterative process the bandwidth of the iterative PLL system is gradually decreased to improve the signal-to-noise ratio of the detected phase as well as to resolve noise-generated phase inconsistencies.     

直流电机的数字同步锁相

在某高速摄影机中,我们采用了同步数字锁相环路,本文叙述该机中直流电机的数字同步锁相原理及其所用数字相位误差积分器线路的构成。     

Properties of Optical Phase-Locked Loop Based on Four Wave Mixing in Semiconductor Laser Amplifiers

In this paper, the properties of the optical phase-locked loop(PLL) based on the four-wave mixing in the semiconductor laser amplifiers (SLAs) are discussed. The components that achieve the function of detecting the bit phase of the input optical signal are concerned and discussed in detail together as a function module named as the optical bit phase detector referred to the general electronic PLL. Therefore, most of the properties of the optical PLL can be analyzed by applying the general phase-locked theory. Here the stability of the optical PLL is discussed. It's shown that the variance of input signal power in the practical application will cause optical PLL system unstable because of its long loop delay. The influence on the output phase jitter of the optical PLL is also investigated.     

多聚赖氨酸诱导的负电性磷脂巨囊泡形变

利用荧光显微技术表征了多聚赖氨酸诱导的负电性磷脂巨囊泡的动力学响应行为.研究发现,多聚赖氨酸可吸附至二油酰磷脂酰胆碱和二油酰磷脂酸混合磷脂巨囊泡的表面,诱导其发生粘连、出"绳"及破裂现象.分析认为,在低盐环境中,膜形变由多聚赖氨酸吸附于二油酰磷脂酸富集区引起的膜两叶应力不对称,以及静电相互作用等因素产生.研究结果对基于聚合物-巨囊泡体系的药物输运控释、细胞形变、微控反应和基因治疗等方面的研究提供有价值的支持.     

Magnetoplex based on MnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanocrystals for magnetic labeling and MR imaging of human mesenchymal stem cells

For efficient labeling and tracking via magnetic resonance (MR) imaging of human mesenchymal stem cells (h-MSCs), magnetic labeling agents must be responsive to an external magnetic field. Thus, we developed ultrasensitive magnetoplex as a magnetic labeling agent composed of PEGylated MnFe₂O₄ nanocrystals (PMNCs) and polycationics (poly-l-lysine, PLL) for efficient labeling of the h-MSCs and monitoring of the transplanted h-MSCs for a long term. PMNCs were prepared by nanoemulsion methods composed of MnFe₂O₄ nanocrystals (MNCs) and amphiphilic polymers (mPEG–dodecanoic acid). The prepared PMNCs exhibited excellent biocompatibility and their polycationic complexes (PMNCs/PLL) demonstrated remarkable sensitivity compared with magnetic iron oxide nanoparticles (MION)/PLL or Ferumoxides/PLL. Furthermore, PMNCs demonstrated the potentials for novel diagnostic and therapeutic strategies with potential applications in various biomedical fields.     

Phaselock system for millimeter-wave Gunn oscillators used in radio astronomy and laboratory spectroscopy

A frequency-agile heterodyne phaselock loop (PLL) system for millimeter-wave Gunn-effect oscillators between 40 and 110 GHz is described. The Gunn oscillators are phase-locked via the bias in an active second-order servo loop. A facility for fast frequency switching with a maximum rate of 10 kHz and a frequency separation up to 80 MHz is provided. Measurements on the spectral characteristics of a phase-locked Gunn oscillator are presented. The described PLL system is used in radio astronomy and laboratory molecular spectroscopy.     

改进支持向量机和常数模算法水声信道盲均衡

针对盲均衡算法收敛速度较慢的问题,提出一种结合改进支持向量机和常数模算法的水声信道盲均衡算法。该算法首先利用具有优异小样本学习能力的支持向量机进行盲均衡器权系数初始化,在完成初始化后切换至运算量较小的常数模算法。考虑到支持向量机本身非自适应运算的限制,在时变水声信道条件下利用经典支持向量机获得的均衡器初始权向量与切换后的信道仍然存在失配。因此,本文导出时变条件下的改进支持向量机用于盲均衡器初始化,改善算法切换时的权系数失配,并结合分数间隔结构和内嵌数字锁相环进一步提高盲均衡算法性能。仿真和湖试实验结果表明:在时变水声信道条件下,本文算法的收敛性能优于经典支持向量机盲均衡算法。      

Phase Lock-In of MM/SUBMM Backward Wave Oscillators: Development, Evolution, and Applications

The development and evolution of a Phase-Lock Loop (PLL) system up to the highest frequencies of Backward Wave Oscillators (BWO) is considered starting from the first submillimeter BWO PLL in 1970. Improvements and increase of working range near to Terahertz are followed. Development of the series of commercial BWO-based millimeter wave frequency synthesizers, extension of the BWO PLL beyond Terahertz as well as recent progress in fast millimeter wave frequency synthesizers are described. Applications of BWO PLL systems for physical and technical measurements are discussed and some proposals for the next generation of BWO-based synthesizers are presented.     

对数比电路原理与低频工作点反馈系统

 在合肥光源注入系统升级改造后，尝试了几种方法来改进机器注入束流稳定性。研制了用于抑制注入过程残余β振荡的水平和垂直方向的工作点振荡抑制模块，尝试了包括逐圈测量和锁相环原理来激励和稳定束流等方法来跟踪工作点变化。详细分析了基于对数比原理的逐圈测量系统，包括单束团和多束团模式，证明在多束团模式下逐圈测量的可行性和意义，更新了数据采集和可远程控制的软件集成环境。     

A Millimeter Wave Phase Locked and Frequency Multiplying Source

A millimeter wave phase locked and frequency multiplying source is proposed in this paper. The design includes an X-band phase locked loop (PLL) frequency synthesizer as the base frequency source, and a monolithic millimeter wave frequency tripler, which is developed by using OMMIC 0.18μm pHEMT process. The PLL and the tripler are integrated in a single circuit board to make a low-cost and compact frequency source with the size of 6cm × 5cm. Measurement shows an output power of more than 4.8dBm at the frequency range from 35 to 36.7GHz. A phase noise of about -92dBc/Hz at 100kHz offset is achieved.     

Protein adsorption and biomimetic mineralization behaviors of PLL-DNA multilayered films assembled onto titanium

Titanium and its alloys are frequently used as surgical implants in load bearing situations, such as hip prostheses and dental implants, owing to their biocompatibility, mechanical and physical properties. In this paper, a layer-by-layer (LBL) self-assembly technique, based on the polyelectrolyte-mediated electrostatic adsorption of poly-l-lysine (PLL) and DNA, was used to the formation of multilayer on titanium surfaces. Then bovine serum albumin (BSA) adsorption and biomimetic mineralization of modified surfaces were studied. The chemical composition and wettability of assembled substrates were investigated by X-ray photoelectron spectroscopy (XPS), fluorescence microscopy and water contact angle measurement, respectively. The XPS analysis indicated that the layers were assembled successfully through electrostatic attractions. The measurement with ultraviolet (UV) spectrophotometer revealed that the LBL films enhanced ability of BSA adsorption onto titanium. The adsorption quantity of BSA on the surface terminated with PLL was higher than that of the surface terminated with DNA, and the samples of TiOH/P/D/P absorbed BSA most. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed that samples of assembled PLL or/and DNA had better bioactivity in inducing HA formation. Thus the assembling of PLL and DNA onto the surface of titanium in turn via a layer-by-layer self-assembly technology can improve the bioactivity of titanium.     

高场核磁共振波谱仪频率合成器设计

提出了一种基于锁相环(Phase-locked Loop, PLL)与直接数字合成(Direct Digital Synthesis, DSS)等技术相结合的高场核磁共振波谱仪频率合成器设计方案．该系统以单片机为控制器完成算法运行、参数配置和CAN 总线通信功能,运用PLL 技术和DDS 技术相结合的频率合成方案,通过两次混频,使频率粗调和细调灵活可控,实现宽带低噪声频率输出．将该频率合成器用于自主研制开发的核磁共振波谱仪上进行实验验证,测试得到的线形和灵敏度均达到指标要求,结果证明该设计方案具有可行性．     

锁相环的相位模型与实验电路

讨论了锁相环的相位数学模型,给出了一种适合于数学的锁相环实验电路．     

New phase and polarization-insensitive receivers for coherent optical fibre communication systems

We propose new phase- and polarisation-insensitive receivers for coherent optical fibre communication systems which have the following characteristic features: (a) insensitivity to LO excess noise in addition to phase- and polarization-insensitivity; (b) absence of optical PLL and polarization control devices; (c) a smaller detector bandwidth requirement than for heterodyne systems; (d) the same source linewidth requirement as for heterodyne systems with non-coherent demodulation; (e) the possibility of a complete optoelectronic integrated circuit (OEIC) version in the future.