Dynamic Behavior of Entanglement Between Two Spatially Separated Atoms in Two Dissipative and Driven Cavity Fields

We consider two two-level atoms, interacting with two independent dissipative cavities, each of which is driven by an external source. The two cavity fields are both initially prepared in the coherent states, and the two two-level atoms are initially prepared in the singlet state ｜ψ^-〉 =（｜eg〉 - ｜ge〉 ） / √2. We investigate the influence of the damping constant n, the intensity of the external sources F, and the relative difference of the atomic couplings r on the entanglement between the two atoms. In the dispersive approximation, we find that the entanglement between the two atoms decreases with the time evolution, and the decreasing rate of entanglement depends on the values of F/k, k/ω, and r. For the given small values of F/k and k/ω, on the one hand, the increasing of r favors entanglement decreasing of the atomic system, on the other hand, when r → 1 the entanglement decreasing becomes slower. With the increasing of the value of k/ω, the influence of r on the decreasing rate of entanglement becomes smaller, and gradually disappears for the big value of k/ω.

Dynamical Properties of Two Coupled Dissipative QED Cavities Driven by Coherent Fields

When two identical QED cavities driven by the coherent fields are located in a uniform environment, in addition to dissipation, there appears an indirect coupling between the two cavities induced by the background fields. We investigate the effects of the coherent fields, the dissipation as well as the incoherent coupling on the following dynamical properties of the system： photon transfer, reversible decoherence, and quantum state transfer, etc. We find that the photons in the cavities do not leak completely into the environment due to the collective coupling between the cavities and the enviroment, and the photons are transferred irreversibly from the cavity with more photons to the cavity with less ones due to the incoherent coupling so that they are equally distributed among the two cavities. The coherent field pumping on the two cavities increases the mean photons, complements the revived magnitude of the reversible decoherence, but hinders the quantum state transfer between the two cavities. The above phenomena may find applications in quantum communication and other basic fields.

Study and Measurement of Glidarc Driven by Magnetic Field

Non-thermal plasma at atmosphere was generated through glidarc discharge driven by magnetic field and observed by using a high speed charge coupled device （CCD） and photo multiplier tube （PMT）. The arc diameter projecting in the direction of arc motion （front-viewed diameter） and the diameter projecting in the perpendicular direction of arc motion （side-viewed diameter） were measured. The effect of both the arc current and the magnetic field was analysed. The front-viewed diameter was compared with the side-viewed one. Simultaneously the electricfield intensity was measured directly and analysed by considering the effect of the external magnetic field and arc current.

Exploration of a New Task-driven Model for Botany Field Practice

In the present context of increasing social demands for natural science education,increasing people s awareness of environmental biodiversity protection,and ecological civilization lifting to the state strategy,it is just the time to explore a new botany field practice model.The attempt of a new task-driven model for botany field practice will greatly enhance students thinking about plants and nature,plants and environment,and plant and ecological civilization,and will inevitably enhance students initiative awareness and practical ability to protect and rationally utilize plant resources.

Determination of the Velocity of a Magnetic-Field Driven Gliding Arc by Using a Photo-Multiplier

The gliding arc is an important approach to production of non-thermal plasma at atmospheric pressure, it can offer high-energy efficiency and high-electivity for chemical reactions. In this paper, the gliding arc driven by the transverse magnetic field is described and its velocity is measured by using a photo-multiplier. The mean velocity of the gliding arc increases with increasing magnetic induced-intensity, and its value varies from 7.8 m/s to 32 m/s.

场驱动医疗微机器人:材料制备工艺不断优化的应用前景

背景:微机器人具有体积小、灵活、靶向性强等特点,可以在狭窄的环境下通过单体或集群的方式完成复杂的工作。随着材料、制备工艺以及驱动方式的不断优化,其在生物医学领域内显示出越来越重要的应用价值。目的:分析场驱动微机器人在生物医学领域的应用并展望其应用前景。方法:以“微机器人,纳米机器人,驱动,生物医学,医疗”为中文关键词,以“microrobots,micro-robots,nanorobots,micromachine,microswimmer,medical”为英文关键词,分别检索万方以及Pub Med数据库,检索时间范围重点为2010年1月至2024年1月,同时纳入少数远期文献。通过阅读文题、摘要初步筛选,排除重复性研究、低质量期刊以及与内容不相关的文献,阅读全文后最终纳入66篇文献进行综述。结果与结论:场驱动医疗微机器人涵盖了磁、光、热、超声及多种混合因素驱动机器人。场驱动机器人已被应用于肠道诊断、药物靶向治疗及干细胞治疗等多个领域。尽管医用微机器人在临床医学中已有少数应用,但大多数还处于理论和实验阶段。医用微机器人的未来面临诸多挑战,如实现大规模制备、进一步提升精确控制、解决回收或体内降解问题,以及所用材料是否会对人体产生不良反应等,此外微机器人还需与相应的微创医学手术相配合。

Stability Analysis of Hybrid-Driven Underwater Glider

Hybrid-driven underwater glider is a new type of tmmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steady- state operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and simulations.and to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.

Design and implementation of high speed TDI CCD timing-driven circuits

The time delay integration charge coupled device(TDI CCD)is the key component in remote sensing systems.The paper analyzes the structure and the working principles of the device according to a customized TDI CCD chip.Employing the special clock resources and large-scale phase locked logic(PLL)in field-programmable gate arrays(FPGA),a timing-driven approach is proposed,using which all timing signals including reset gate,horizontal and vertical timing signals,are implemented in one chip.This not only reduces printed circuit board(PCB)space,but also enhances the portability of the system.By studying and calculating CCD parameters thoroughly,load capacity and power consumption,package,etc,are compared between various candidates chips,and detailed comparison results are also listed in table.Experimental results show that clock generator and driving circuit satisfy the requirements of high speed TDI CCD.

基于POD/DMD降阶模型的离心泵蜗壳内非稳态流动分析

为深入研究离心泵蜗壳内非线性耦合流动的本质流动特征,本文以一单级单吸式离心泵蜗壳为研究对象,分别采用本征正交分解和动态模态分解2种降阶模型对蜗壳内非定常流场数据进行模态分析,获取流场主导流动结构,并对原流场进行重构。研究发现:蜗壳内流结构主要由速度正负交错,并且周期性特征与叶频及其倍频相关的成对涡旋组成。本征正交分解和动态模态分解方法均可以捕捉流场主要流动结构,并对原流场进行准确还原,两者重构流场与原流场的均方根误差均在0.4%以内。尽管本征正交分解方法在重构流场时整体均方根误差更小,但无法获取单频率流动结构,而动态模态分解方法可以获得不同频率流动结构对流场的贡献,从而捕捉到复杂流场中的不稳定模态。研究成果可以为增强离心泵全局流动的认知、关键水力部件优化设计及发展主/被动流动控制提供理论参考。

气流场驱动喷射3D打印熔融聚乳酸微细纤维及表面浸润性调控

提出了一种高速气流场驱动喷射高效三维(3D)打印熔融聚乳酸微细纤维的方法,分析了高速气流致熔融材料剪切破碎原理,研究了打印工艺中供料气压、气流流速、打印高度等关键参数对微细纤维直径分布及结构孔隙率、截面尺寸的影响规律。并对所获得的聚乳酸微细纤维进行了表面浸润性测试。结果表明,该工艺相对于静电纺丝等微细纤维制造方法,加工效率提高10倍以上。通过控制不同的打印参数,可以有效实现纤维直径在6~18μm、孔隙率在55%~96%范围内的有效调控。通过3D打印工艺,可实现具有宏观路径可控、微观具有高孔隙率微纤维结构的制作。表面浸润性结果显示,打印微细纤维由于材料分子基团及高孔隙率综合作用,具有疏水性及粘附性特征,通过对微观局部进行亲水处理,实现了同一材料局部疏水和亲水共存结构的制作,证明了该方法表面浸润性调控的有效性。

Analytical solutions for a doubly driven two-level atom

We have deduced analytical solutions of an energy level diagram of the doubly driven/dressed atom for a two-level atom exposed to a strong near-resonant bichromatic laser field in a special case, i.e., the bichromatic field with frequencies ω1 and ω2, and Rabi frequencies ？1 and ？2, in which the first coupling field of ？1 acts on the bare atomic levels, and then the resulting singly dressed states are driven by the second coupling field of ？2, thus resulting in the doubly dressed atom.We have measured the probe absorption spectra of a doubly driven two-level atom. The system consists of 52S1/2, F= 2 and 5~2P_（3/2）, F＇= 3 states of ^（87）Rb atoms in a magneto-optical trap（MOT） as well as the cooling/trapping beams and an additional coupling field. As for the spectroscopic properties of the doubly driven two-level atom, theoretical analytical solutions are in general agreement with the experimental spectrum as a whole.

ELECTRIC FIELD MICROSENSOR BASED ON THE STRUCTURE OF PIEZOELECTRIC INTERDIGITATED CANTILEVER BEAMS

This paper presents the design, fabrication, and preliminary experimental result of an electric field microsensor based on the structure of piezoelectric interdigitated cantilevers with staggered vertical vibration mode. The working principle of this electric field microsensor is demonstrated, and the induced charges and structural parameters of this microsensor are simulated by the finite element method. The electric field microsensor was fabricated by Micro-Electro Mechanical Systems(MEMS) technique. Each cantilever is a multilayer compound structure(Al/Si3N4/ Pt/PZT/Pt/ Ti/SiO 2/Si), and Piezoelectric, PieZ oelectric ceramic Transducer(PZT)(PbZ rxTi(1–x)O3) layer, prepared by sol-gel method, is used as the piezoelectric material to drive the cantilevers vibrating. This electric field microsensor was tested under the DC electric field with the field intensity from 0 to 5×104 V/m. The output voltage signal of the electric field microsensor has a good linear relationship to the intensity of applied electric field. The performance could be improved with the optimized design of structure, and reformative fabrication processes of PZT material.

建筑屋面风雨场及突出建筑立面风驱雨的实测研究

文章对某多层建筑屋面区域风驱雨(wind-driven rain,WDR)开展实测,结合3类典型降雨事件的分析,揭示大气湍流特征以及风速、风向对雨滴的影响特性,并针对突出屋面建筑,实测分析立面WDR分布特性,量化国际标准化组织(International Organization for Standardization,ISO)半经验模型对突出屋面建筑WDR预测的偏差。结果表明,在3类降雨事件中,湍流度、阵风因子和湍流积分尺度的实测值与基于地面实测建立的公式理论值之间存在较大差异;实测的雨滴数量与标准M-P谱计算的雨滴数量差值最大为125个。在风速和雨强差异较小时,建筑立面WDR分布受来流与立面夹角的影响显著。由于ISO半经验模型是基于地面实测建立的,其对突出屋面建筑WDR的预测存在偏差,在模型适用的降雨条件下实测值约为ISO预测值的2倍。

电离层重力电流与压力梯度电流的模拟研究

风场发电机驱动产生电离层电流,其主要分布在日侧E区.电离层电流会产生显著的地磁扰动,这也是地磁静日(Solar quiet,S_(q))变化的主要来源.但是,电离层区域的其他作用力,包括等离子体重力和压力梯度力,同样能驱动等离子体跨越磁力线,进而影响了电离层电流.本文首先探讨了等离子体重力和压力梯度力在电离层发电机过程中的作用机制,随后利用数值模拟得到重力电流和压力梯度电流.通过分析重力电流和压力梯度电流的时空分布,我们发现它们的分布区域与电离层赤道异常(EIA)重合,重力电流方向是地磁东向的,而压力梯度电流在EIA结构的底部是东向的而顶部是西向的.除此之外,我们发现重力和压力梯度电流的经度分布受到地磁场和潮汐的影响,其中电流强度与磁场强度反相关.

基于场驱动的X波段龙勃透镜平面化设计研究

龙勃透镜天线因其多种优异属性,如多波束能力、宽角扫描、高增益等,是应用于雷达、卫星通信等电磁领域的重要器件。然而传统球形龙勃透镜因为体积、重量等问题大大限制了其在某些场景的应用。为了解决龙勃透镜的平面化、共形化等问题。文章提出并设计了一种用于X波段(8 GHz~12 GHz)应用的平面型龙勃透镜。利用超材料结构思想和场驱动设计技术实现了平面型龙勃透镜的介电常数梯度渐变和轻量化。采用12 dB增益喇叭天线对所设计的龙勃透镜进行仿真,在12 GHz的工作频率上获得高达14.1 dB的天线增益,与球形龙勃透镜相比,模型总体积减少了78%。此外,该平面型龙勃透镜模型,是基于有限元分析的透镜辐射分布电场驱动求解构建的,该方法可以为复杂结构透镜部件的开发及共形化设计提供创新思路。

一种利用远场数据恢复Dirichlet特征值的神经网络方案

探讨了声场中利用远场数据重构具有Dirichlet边界条件的障碍物的特征值反问题,提出了一种基于数据驱动的神经网络方案。首先针对具有Dirichlet边界条件的障碍物建立内特征值问题和外散射问题的数学模型,然后构建一个具有序列对序列结构的多层前馈神经网络,该网络采用反向传播误差和自学习的方式更新网络中的超参数,最后在散射体信息未知的前提下,利用远场数据重构障碍物的Dirichlet特征值。数值实验表明该方法可以有效地重构障碍物的Dirichlet特征值。

铁电效应调控的高性能p-NiO/i-BaTiO_(3)/n-ITO自供能紫外光电探测器

近年来,自供能的紫外光电探测器由于无需任何外部偏压即可工作而成为军事和民用领域的研究热点。其中,钛酸钡(BTO)作为一种宽禁带铁电材料,拥有良好的铁电、压电和热电性能,可以产生本征自发极化场来分离光生载流子,从而实现自供能紫外光电探测。到目前为止,基于BTO的自供能光电探测器已经取得了巨大进展,然而,除了使用高质量的单晶材料外,所报道的器件往往表现出低响应度(10^(-8)~10^(-7) A·W^(-1))。本文利用低成本的射频溅射技术,制造了一种高性能的NiO/BTO/ITO p-i-n异质结构自供能紫外光电探测器。通过将BTO的铁电去极化场和p-i-n结的内建电场耦合,能有效提高光生载流子的分离和迁移。因此,该器件在正极化态下255 nm波长紫外光照射下的响应度可以达到3.4×10^(-5) A·W^(-1),远远高于其他已报道的基于非晶态和陶瓷BTO制备的紫外光电探测器。此外,该器件具有0.3 s/0.4 s的快速响应时间。本工作为提高BTO光电探测器的性能提供了一种新的策略。

两个耦合驱动谐振子精确的经典与量子动力学研究

谐振子模型作为一类可严格解析求解的体系,在物理学中占据重要地位,是描述许多物理过程非常有力的理论模型,而关于驱动谐振子的研究却较少涉及.本文研究了两个耦合驱动谐振子模型精确的经典与量子动力学.在经典力学框架下利用哈密顿正则方程给出含时驱动外场作用在两个耦合谐振子体系的精确能量值.在量子力学框架下考虑非含时驱动外场,给出系统的能量本征值和对应的本征态.考虑含时驱动外场,利用算子代数方法得到该量子体系t时刻的波函数和对应的能量期望值.由于在量子力学框架下微观粒子具有波粒二象性,因此两个驱动耦合谐振子体系的经典与量子动力学存在明显差异.

基于电场驱动喷射微3D打印的曲面透明电加热玻璃技术

为了解决高性能曲面透明电加热玻璃制造工艺复杂和制备成本高的问题,提出了一种基于电场驱动喷射微3D打印制造曲面透明电加热玻璃的新方法,并阐述了该工艺流程;通过实验揭示了主要打印参数对制造曲面透明电加热玻璃银线线宽的影响规律;使用优化的打印参数在曲面透明玻璃上制备了有效加热面积为35 mm×40 mm,线宽为90μm,周期为3000μm,附着力为4B,透光率为90%,电阻为1.6Ω,银线为金属网栅结构的曲面透明电加热玻璃。实验结果表明,该打印方法工艺简单,利用该方法制造的曲面透明电加热玻璃具有附着力好、透光率高和加热性能良好等优点,为实现低成本、高性能的曲面透明电加热玻璃的工业化制造提供了一种全新的解决方案。

基于结构化潜码引导NeRF的语音驱动人脸重演

语音驱动的人脸重演的目标是生成与输入语音内容相匹配的高保真人脸面部动画.然而,由于音频与视频模态之间存在鸿沟,当前方法难以实现高质量的面部重演.针对现有方法保真度低、唇音同步效果差等问题,提出一种基于结构化潜码引导隐式神经表示的语音驱动人脸重演方法,以人脸点云序列作为中间表示,将语音驱动人脸重演分解为跨模态映射和神经辐射场渲染两大任务分别解决.首先,通过跨模态映射从音频预测人脸表情系数,利用人脸三维重建技术获得人脸身份系数;然后,基于3DMM模型合成人脸点云动画序列;接着,使用顶点位置信息构建结构化隐式神经表示,回归场景中每个采样点的密度和颜色值;最后,通过体绘制技术渲染人脸RGB帧,并装配到原图像中.在多个时长为3~5 min的单人演讲视频上的可视化比较、量化评估、主观评估等实验结果表明,文中所提方法在唇音同步效果与图像生成精度上优于AD-NeRF等方法,能够实现高保真语音驱动人脸重演.