分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-15
摘要： 天环一号（CAT-1: China Astro-Torus 1）是一个悬浮偶极场磁约束装置，主要用于偶极场等离子体物理实验研究，要求中心悬浮超导磁体在无冷却和无电源条件下稳定悬浮至少5h。本文设计了超导托举磁体与中心悬浮磁体环耦合的悬浮控制系统，为确保1200 kg、5 MA中心悬浮磁体环稳定悬浮，完成了控制系统的Simulink模型建立和仿真，基于 Routh-Hurwitz稳定判据，研究了PID（Proportion-Integral-Derivative）控制策略对稳定控制影响，确定了稳定控制参数选取的范围：理想条件下PD（Proportion-Derivative）控制系统上升时间为0.1545 s、峰值时间为0.6283 s、调节时间0.0848 s。结果表明：基于PID能够在较短的时间内将悬浮超导环恢复在预设平衡位置，采用合适的启动方式可极大的降低电路的负载。本结果为悬浮超导悬浮偶极场装置设计研发提供关键技术支撑。
分类： 力学 >> 力学其他学科 提交时间： 2024-04-19 合作期刊: 《应用力学学报》
摘要： 以二维二轴编织的SiC/SiC复合编织管为研究对象,研究其抗热冲击性能及失效机理。自主搭建了基于石英灯辐照加热的循环热冲击试验平台,基于该平台开展了SiC/SiC复合编织管的循环热冲击试验考核,并对循环热冲击后的复合编织管进行了径向压缩测试,探究了复合编织管力学性能与破坏机理,拟合得到了热冲击强度退化经验公式。研究结果表明,搭建的循环热冲击试验平台能够模拟快速升降温的实际服役环境,最高升温、降温速率在试验过程中分别可达约40、60 ℃/s。随着热冲击循环次数的增加,SiC/SiC复合编织管环向拉伸强度下降,且降幅随之增大。热冲击产生的热应力导致纤维周围的基体产生微裂纹,弱化了纤维束与基体之间的连接,这是复合编织管强度降低的原因之一。拟合的强度退化经验公式能够准确描述强度退化规律,可以满足工程应用需求。
提交时间： 2024-04-18
摘要： 喷淋雾化被广泛应用于核动力设备中，以保证其安全稳定运行。喷淋时，部分液滴会撞击设备壁面，以液膜的形式进行扩展和演变。基于 Fluent DPM-to-VOF 进行了液滴射流撞壁研究，使用两液滴滴落过程实验图像验证了模拟方法的准确性，研究了液滴射流注入速度、入射角度对壁面液膜形态的影响规律，得到了液滴溅射率随入射条件的变化情况，并分析了液滴撞击壁面时重力、表面张力、速度分量等对液膜形态扩展过程、液滴溅射率的影响。研究发现，增大注入速度能加大对液膜的扰动，液膜与壁面的接触面积显著增大，液膜区宽度和高度增加；增大入射角度对液膜形态的改变影响较大，体现在液膜区宽度增加和液膜区高度减小，液膜表面稳定性减低。溅射率随着注入速度和入射角度的增大而增大，其中，入射角度对溅射率的影响更大。
分类： 心理学 >> 认知心理学 分类： 心理学 >> 教育心理学 提交时间： 2024-04-04
摘要： 特殊教育教师在执行课堂教学任务时很容易忽视学生的离座行为，这会带来很多不可预见的安全隐患。座位安排是教师管理离座行为的常见手段，那么从座位安排的角度，教师对离座行为的觉察是否存在注意优势区?本研究结合无意视盲研究范式与课堂管理任务，通过2个实验探究真实课堂场景下，学生的空间位置序列对教师觉察离座行为的影响。结果发现，教师对学生离座行为确实存在一定的优势注意区：在静态课堂情境和动态课堂情境中，前排学生的离座行为都更容易被觉察；静态情境中，处于中心位置学生的离座更不容易被觉察，但动态情境中无此中心抑制效应。该结果为教师合理安排特殊学生座位提供了科学依据。
分类： 心理学 >> 认知心理学 分类： 心理学 >> 社会心理学 提交时间： 2024-04-02
摘要： 对何为公正的判断决定着道德判断的合理性。公正的判断需要有清晰的逻辑结构，包括对证据的辨析，也包括对判断准则合理性的辨析。在社会事务的公正性评价中，原则性的评价应优先，功利主义式的社会效用评价应居其次。尽可能地查清事件的相关信息，是进行公正的道德判断的数据基础；全面充分的换位思考是进行公正的道德判断的方法基础；以理性、公正、平等、博爱、宽容等为特征的普适性的价值观是进行公正的道德判断的准则基础。
分类： 心理学 >> 管理心理学 提交时间： 2024-04-08
摘要： 本研究基于边界理论和资源保存理论分析工作场所之中的工作状态转换活动影响员工日常工作效率的作用机制和边界条件。通过对来自70名被试603个观察值进行路径分析发现: (1)在个体内层次, 员工上午和下午的工作状态转换活动时间与上午和下午的工作投入关系为倒U型。(2)工作状态转换活动对工作投入的作用效果取决于活动时段和活动惯常性：员工上午的工作状态转换活动时间与工作投入的关系在活动惯常性较强的情况下呈倒U型；下午的工作状态转换活动时间与工作投入关系在活动惯常性较弱的情况下呈倒U型。(3)工作状态转换活动通过影响工作投入对工作目标进展的间接效应部分受员工作息时间型的调节：晨型员工上午工作状态转换活动通过上午工作投入对工作目标进展产生正向影响；无论何种作息时间型的员工，下午工作状态转换活动都可以通过下午工作投入对工作目标进展产生正向影响。本研究将工作状态转换活动的研究情境从工作场所之外拓展到从工作场所之中, 探讨这类活动对员工工作效率的影响，加深了对工作状态转换的作用机制和边界条件的认识。
分类： 心理学 >> 社会心理学 提交时间： 2024-04-07
摘要： 本研究采用污名化诱导网络投球范式，通过2个实验探讨社会拥挤对社会排斥行为的影响机制和群体效应。实验结果均显示，拥挤感启动后个体的排斥次数显著更多，主观排斥显著更高；实验1进一步发现控制感和负性情绪在拥挤感和排斥次数及主观排斥关系中的链式中介作用显著；实验2则从群体类型切入，发现陌生人条件下拥挤感启动会显著增加排斥次数和主观排斥，而熟人条件下拥挤感启动不会显著增加排斥次数和主观排斥。本研究表明：社会拥挤会导致更多的社会排斥行为，并且控制感和负性情绪在该路径上起完全链式中介作用；同时，群体类型能够有效调节社会拥挤对社会排斥行为的影响，即当拥挤群体为陌生人时，社会拥挤才会导致更多的社会排斥行为。
分类： 心理学 >> 社会心理学 提交时间： 2024-04-08
摘要： 3个实验探究了任务型共同经历对合作行为的直接和间接影响。实验 1分析了公共物品困境中共同/不同任务经历参与者合作行为的差异性。实验2通过测量信任和人际距离, 探究了共同经历影响合作行为的潜在机制。实验3对任务设置了目标, 通过任务目标的达成与否来操纵成败, 考察了经历成败对合作行为的影响。结果表明：(1)任务型共同经历相比于不同经历更能促进合作行为；(2)信任和人际距离在共同经历对合作行为的影响过程中起中介作用；(3)共同经历成功的个体相比共同经历失败的个体之间有更高的合作行为, 即拥有共同经历的双方只可“同光荣”不可“共耻辱”。
分类： 心理学 >> 应用心理学 提交时间： 2024-04-11
摘要： 字体强调被证明影响了中性文本的加工过程。本研究利用功能性近红外光谱成像技术，通过操纵句子中关键词的情绪效价和字体强调状态，进一步拓展探讨了字体强调对情绪加工的影响及其老化效应。结果显示，控制条件下，相比于年轻人，老年人阅读积极词时在右侧腹外侧前额叶上的激活程度呈现出更低的趋势，在阅读消极词时其激活程度更高。强调条件下，老年人与年轻人之间的激活差异消失。该结果表明，字体强调依附右侧腹外侧前额叶，在情绪加工中以自下而上的方式捕获了注意，加强了读者对情绪信息的评价与整合，促进了对情绪信息的控制加工。不过，字体强调对老年人与年轻人的作用机制不同。字体强调促使老年人产生情绪的积极效应，但激发了年轻人的消极情绪偏好。
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-15
摘要： 活化-燃耗计算是反应堆分析的重要组成部分，需要耦合临界输运程序和点燃耗程序来迭代求解。LightAB（Light Activation and Burnup）是一个新的轻量化的通用活化-燃耗分析程序，可以用来处理活化-燃耗系统。LightAB采用了基于燃耗计算程序ORIGEN-2和ORIGEN-S的燃耗数据库，采用了处理刚性燃耗系统的切比雪夫有理逼近算法（Chebyshev rational approximation method, CRAM）。LightAB支持在衰变模式，定通量模式和定功率模式下的活化-燃耗计算。为了验证LightAB程序的正确性，计算237Np衰变问题和锆（Zr）合金的固定通量辐照问题，与燃耗程序ORIGEN-2.1程序的结果一致。实现了LightAB和RMC程序的耦合并用于计算加压水慢化冷却反应堆压水堆（Pressurized Water Reactor, PWR）栅元燃耗基准题、PWR组件燃耗问题、经合组织/核能机构（OECD/NEA）快堆燃耗基准问题，计算结果与RMC的燃耗计算模块一致。在超钚同位素的辐照生产与RMC对比模拟计算中LightAB展现出良好的应用前景。
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： we investigate the transmission of probe laser beam in a coupled-cavity system with polaritons by using standard input-output relation of optical fields, and proposed a theoretical schema for realizing a polariton-based photonic transistor. On account of effects of exciton-photon coupling and single-photon optomechanical coupling, a probe laser field can be either amplified or attenuated by another pump laser field when it passes through a coupled-cavity system with polaritons. The Stokes and anti-Stokes scattered effect of output prober laser can also be modulated. Our results open up exciting possibilities for designing photonic transistors.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The miniaturization and mobility of computer vision systems are limited by the heavy computational burden and the size of optical lenses. Here, we propose to use a ultra-thin diffractive optical element to implement passive optical convolution. A division adjoint opto-electronic co-design method is also proposed. In our simulation experiments, the first few convolutional layers of the neural network can be replaced by optical convolution in a classification task on the CIFAR-10 dataset with no power consumption, while similar performance can be obtained.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Diffraction gratings with high upward diffraction efficiency and large effective length are required for chip-scale light detection and ranging. In this paper, we propose a diffraction grating based on a multilayer silicon nitride waveguide, which theoretically achieves an upward diffraction efficiency of 92$\%$, a near-field effective length of 376 $\mu m$ and a far-field divergence angle of 0.105$^{\circ}$ at a wavelength of 850 nm. The diffraction grating has a high tolerance to process variations based on Monte Carlo Analysis. When the conditions are $\pm$5$\%$ layer thickness variation, $\pm$50 nm lithographic variation and $\pm$20 nm wavelength drift, more than 71$\%$ of the grating samples have a diffraction efficiency higher than 80$\%$, and 100$\%$ of the samples have an effective length larger than 200 $\mu m$ (corresponding to a far-field divergence <0.2$ ^{\circ}$). Furthermore, the near-field effective length of the grating with an upward diffraction efficiency above 90$\%$ can be adjusted from hundreds of microns to centimeters by changing the etching layer thickness and the grating duty cycle. This diffraction grating has potential application in optical sensing and imaging from visible to near-infrared wavelengths.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Electromagnetic spins, including longitudinal and transverse ones, have been playing important roles in light-matter interactions. Here, we formulate a unified equation to uncover the physical origins and topological properties of longitudinal and transverse spins in a generic electromagnetic field. The equation reveals universally that the transverse spin is locked with the kinetic momentum and originated from the transverse inhomogeneities of field, whereas the helix-dependent longitudinal spin orients parallel to the local wavevector. Remarkably, a hidden extraordinary helix-dependent transverse spin possessing helix-dependent spin-momentum locking is discovered and the number of locking states consistent with the nontrivial topological spin Chern number. Furthermore, this spin which determines the inverted helical components is related to the Berry curvature closely. The findings, which are demonstrated experimentally by measuring the three-dimensional spin components in the focusing configuration, will deepen the understanding the underlying physics of spins and open an avenue for chiral quantum optical applications.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Polarization vectors of light traveling in a coiled optical fiber rotate around its propagating axis even in the absence of birefringence. This rotation was usually explained due to the Pancharatnam-Berry phase of spin-1 photons. Here, we use a purely geometric method to understand this rotation. We show that similar geometric rotations also exist for twisted light carrying orbital angular momentum (OAM). The corresponding geometric phase can be applied in photonic OAM-state-based quantum computation and quantum sensing.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Optical forces in the near fields have important applications in on-chip optical manipulations of small particles and molecules. Here, we report a study of optical force and torque on small particles induced by the optical polarization singularities of a gold cylinder. We show that the scattering of the cylinder generates both electric and magnetic C lines (i.e., lines of polarization singularities) in the near fields, and the C lines can induce complex force and torque on a dielectric/magnetic particle. The force and torque manifest dramatic spatial variations with interesting symmetry properties, providing rich degrees of freedom for near-field optical manipulations. The study, for the first time to our knowledge, uncovers the effect of optical polarization singularities on light-induced force and torque on small particles. The results contribute to the understanding of chiral light-matter interactions and can find applications in on-chip optical manipulations and optical sensing.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： How migratory birds can find the right way in navigating over thousand miles is an intriguing question, which much interested researchers in both fields of biology and physics for centuries. There several putative proposals that sound intuitively plausible all remain contested so far because those hypothesis-models of magnetoreceptor to sense geomagnetic field need either extremely high sensitivity or humankind-like intelligence to guide. Here we explore theoretically that the birds can navigate to their destination through an entirely new scenario to sense the geomagnetic field. Our proposal is based on separate peaks of the resonance-fluorescence spectrum of a four-level system derived from the ferric sulfide cluster which exists in a protein complex (Drosophila CG8198) of migratory birds. As the separation of spectral peaks contains information about geomagnetic field at both current location and birthland, the change of such separation cues the bird to choose a right direction to move and double-resonance emerges once arrived the destination. Our theoretical mechanism can explain previous experiments on the disorientation of migratory birds caused by oscillating magnetic field naturally and more precisely. This work provides insight to explain migratory navigation and motivates possible manmade practical devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Narrow linewidth laser(NLL) of high frequency stability and small form factor is essential to enable applications in long range sensing, quantum information and atomic clocks. Various high performance NLL have been demonstrated by Pound-Drever Hall(PDH) lock or self injection lock(SIL) of a seed laser to a vaccum-stabilized FP cavity of ultrahigh quality factor(Q). However they are often complicated lab setups due to the sophisticated stabilizing system and locking electronics. Here we report a compact NLL of 68mL volume, realized by SIL of a diode laser to a miniature FP cavity of 7.7x108 Q and 0.5mL volume, bypassing table-size vaccum, thermal and vibration isolation. We characterized the NLL with a self-delayed heterodyne system, the Lorentzian linewidth reaches 60mHz, and the integrated linewidth is ~80Hz. The frequency noise performance exceeds that of commercial NLLs and the best reported hybrid-integrated NLL realized by SIL to high Q on-chip ring resonators. Our work marks a major step toward a field-deployable NLL of superior performance utilizing ultra-high Q FP cavity.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Conventional coherent absorption occurs only when two incident beams exhibit mirror symmetry with respect to the absorbing surface, i.e., the two beams have the same incident angles, phases, and amplitudes. In this work, we propose a more general metasurface paradigm for coherent perfect absorption, with impinging waves from arbitrary asymmetric directions. By exploiting excitation of unidirectional evanescent waves, the output can be fixed at one reflection direction for any amplitude and phase of the control wave. We show theoretically and confirm experimentally that the relative amplitude of the reflected wave can be tuned continuously from zero to unity by changing the phase difference between the two beams, i.e. switching from coherent perfect absorption to full reflection. We hope that this work will open up promising possibilities for wave manipulation via evanescent waves engineering with applications in optical switches, one-side sensing, and radar cross section control.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Lingya Yu
Zengbo Wang
Lizhou Xu
Liyang Yue
Bing Yan
Igor V. Minin
Oleg V. Minin
Baidong Wu
Yiduo Chen
摘要： Photonic hook (PH) is a new type of artificial self-bending beam focused by a dielectric particle-lens with a curved waist smaller than the wavelength, which has the potential to revolutionize mesoscale photonics in many applications, e.g., optical trapping, signal switching, imaging, etc. In this paper, we discover a new mechanism that the highly curved PHs can be realised by the light interaction with the fully or partially metal-coated microchannels. The generated W-shaped and J-shaped PHs have bending angles exceeding 80-degree. Compared to other PH setups, the proposed design has a larger range to flexibly control the bending angle through the coating process and can be easily integrated with the established microfluidic systems.
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