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Efficient second and third harmonic generation in dual-layer lithium niobate microdisk resonator

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 33-38页

作者： Zhenzhong Hao Xiao Wu Qiang Luo Zhang Li Rui Ma fang bo Feng Gao Guoquan Zhang Jingjun Xu MOE Key Laboratory of Weak-Light Nonlinear Photonics TEDA Institute of Applied Physics and School of PhysicsNankai UniversityTianjin 300457China

Lithium niobate thin film frequency doubler has extensive applications in the preparation of classical and quantum *** this study,we successfully fabricated microdisk resonators with a quality factor of 2.2×10^(5) in reverse-polarization dual-layer x-cut lithium niobate for the first *** on the modal phase matching condition,efficient second harmonic generation with a record normalized conversion efficiency of~56000%W-1 and cascaded third harmonic generation with an efficiency of~6500%W-2 were obtained in the microdisk *** with the periodically poled lithium niobate microcavity,the complex domain structure preparation processes are *** work provides a scheme for achieving highly efficient second-order nonlinear effects in non-periodically poled microcavities.

关键词： harmonic lithium niobate

Numerical Simulation of Oil-Water Two-Phase Flow in Low Permeability Tight Reservoirs Based on Weighted Least Squares Meshless Method

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Fluid Dynamics & Materials Processing 2024年第7期20卷 1539-1552页

作者： Xin Liu Kai Yan bo fang Xiaoyu Sun Daqiang Feng Li Yin School of GeoSciences Yangtze UniversityWuhan430100China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Southwest Petroleum University) Chengdu610000China Downhole Service Company Petro China Qinghai Oilfield CompanyHaixi817000China Research Institute of Drilling and Production Technology Petro China Qinghai Oilfield CompanyDunhuang736200China PetroChina Qinghai Oilfield Company The Third Oil Plant Dunhuang736200China

In response to the complex characteristics of actual low-permeability tight reservoirs,this study develops a meshless-based numerical simulation method for oil-water two-phase flow in these reservoirs,considering complex boundary *** radial basis function point interpolation,the method approximates shape functions for unknown functions within the nodal influence *** shape functions constructed by the aforementioned meshless interpolation method haveδ-function properties,which facilitate the handling of essential aspects like the controlled bottom-hole flow pressure in horizontal ***,the meshless method offers greater flexibility and freedom compared to grid cell discretization,making it simpler to discretize complex geometries.A variational principle for the flow control equation group is introduced using a weighted least squares meshless method,and the pressure distribution is solved *** results demonstrate that the computational outcomes of the meshless point cloud model,which has a relatively small degree of freedom,are in close agreement with those of the Discrete Fracture Model(DFM)employing refined grid partitioning,with pressure calculation accuracy exceeding 98.2%.Compared to high-resolution grid-based computational methods,the meshless method can achieve a better balance between computational efficiency and ***,the impact of fracture half-length on the productivity of horizontal wells is *** results indicate that increasing the fracture half-length is an effective strategy for enhancing production from the perspective of cumulative oil production.

关键词： Weighted least squares method meshless method numerical simulation of low permeability tight reservoirs oil-water two-phase flow fracture half-length

Flexible tuning of multifocal holographic imaging based on electronically controlled metasurfaces

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Photonics Research 2024年第1期12卷 61-69页

作者： OWEN ZENG CHENXIA LI bo fang ZHI HONG XUFENG JING Institute of Optoelectronic Technology China Jiliang UniversityHangzhou 310018China Centre for THz Research China Jiliang UniversityHangzhou 310018China College of Metrology&Measurement Engineering China Jiliang UniversityHangzhou 310018China

Programmable hyper-coded holography has the advantage of being programmable as well as being flexibly *** coded metamaterials with excellent electromagnetic modulation capability and the ability to control the phase to modulate the spatial radiation field through external excitation in the form of switching can be used to realize low-cost digital *** design a 1-bit encoded programmable metasurface,which is electrically connected to control the PIN diode in the switching state and to switch the condition of each metasurface cell between“0”and“1.”Using the designed programmable metasurface,we can randomly encode the cell structure to realize single-focus focusing,multi-focusing,and simple holographic letter *** on the nonlinear holographic model,we employ the Gerchberg-Saxton improvement algorithm to modulate the energy distribution at the focus by adjusting the phase ***,we introduce the Fourier convolution principle to regulate the holographic imaging focus flexibly.

关键词： holographic letter excitation

Value of negative pressure sealing drainage on wound healing of Gustilo IIIB and IIIC open fractures

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World Journal of Clinical Cases 2024年第20期12卷 4199-4205页

作者： bo fang Yong-Sheng Wang Wei Li Kai Ying Gang Zong Department of Trauma Surgery The Second People’s Hospital of DalianDalian 116019Liaoning ProvinceChina

BACKGROUND Gustilo III fractures have a high incidence and are difficult to *** often experience difficulty in wound *** pressure drainage technology can help shorten wound healing time and has positive value in improving patient *** To explore the clinical value of the negative pressure sealing drainage technique in wound healing of Gustilo IIIB and IIIC open *** Eighty patients with Gustilo IIIB and IIIC open fractures with skin and soft tissue injuries who were treated in the Second People’s Hospital of Dalian from March 2019 to December 2021 were selected as the research *** were divided into a study group(n=40,healed with negative pressure closed drainage)and a control group(n=40,healed with conventional dressing changes)according to the variation in the healing they *** efficacy of the clinical interventions,the variations in the regression indicators(time to wound healing,time to fracture healing,time to hospitalization),and the conversion and healing of bacterial wounds were compared 1-3 mo after the *** The total effective rate of patients among the study group was 95.00%(38/40),which was notably higher than 75.00%(30/40)among the control group(P<0.05).The wound healing time,fracture healing time,and hospital stay of the patients in the study group was shorter than the control group(P<0.05).After the intervention,the negative bacterial culture at the wound site rate and wound healing rate of the patients among the study group increased compared to the control group(P<0.05).CONCLUSION Negative pressure sealing and drainage technology has a good therapeutic effect on patients with Gustilo IIIB and IIIC open fracture wounds with skin and soft tissue *** can notably enhance the wound healing rate and the negative rate of bacteria on the wound surface and help to speed up the recovery process of patients.

关键词： Negative pressure closed drainage Gustilo type III open fracture Wound healing Clinical outcome Research value

Focus control of wide-angle metalens based on digitally encoded metasurface

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Opto-Electronic Advances 2024年第8期7卷 26-41页

作者： Yi Chen Simeng Zhang Ying Tian Chenxia Li Wenlong Huang Yixin Liu Yongxing Jin bo fang Zhi Hong Xufeng Jing Institute of Optoelectronic Technology China Jiliang UniversityHangzhou 310018China Centre for THz Research China Jiliang UniversityHangzhou 310018China College of Metrology&Measurement Engineering China Jiliang UniversityHangzhou 310018China College of Information Engineering China Jiliang UniversityHangzhou 310018China

Based on the principle of super-symmetric lens with quadratic phase gradient transformation, combined with the principle of digital coding of metasurface, we propose a wide-angle coded metalens for focusing control in two-dimensional space. This metalens achieves focus shift in the x-direction by changing the oblique incidence angle of the incident wave,and focus control in the y-direction by combining with the convolution principle of the digitally coded metasurface to achieve flexible control of light focusing in the two-dimensional plane. The metasurface unit is mainly composed of threelayer of metal structure and two layers of medium, and the transmission phase is obtained by changing the middle layer of metal structure, which in turn obtains the required phase distribution of the metalens. The design of the metalens realizes the function of the lens with a large viewing angle at the x-polarized incidence, and realizes two-dimensional focus control. Experimentally, we prepared the designed coding metalens and tested the focus control function of the wide-angle coding metalens. The experimental results are in good agreement with the design results.

关键词： metasurface metalens wide-angle coding

金融高水平开放的生成逻辑、现实困境与策略选择

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财经问题研究 2024年第6期 31-42页

作者：张方波中国社会科学院财经战略研究院北京100006

党的二十大报告明确提出,“推进高水平对外开放。”这成为后续推进金融高水平开放的根本遵循。本文在梳理马克思主义者关于金融资本相关论述的基础上,提炼出金融高水平开放的生成逻辑,即金融高水平开放是在货币开放的基础上,金融资本借... 详细信息

党的二十大报告明确提出,“推进高水平对外开放。”这成为后续推进金融高水平开放的根本遵循。本文在梳理马克思主义者关于金融资本相关论述的基础上,提炼出金融高水平开放的生成逻辑,即金融高水平开放是在货币开放的基础上,金融资本借助于国际金融机构和金融市场等载体实现跨境自由流动并完成积累和增殖,同时规避货币、货币索取权或证券形式的权利证书的快速积累对国内市场形成冲击的经济过程。中国金融开放的实践进程丰富了这一逻辑,即金融开放为金融资本跨境自由流动夯实了基础,金融资本跨境流动的载体种类不断扩围,以及积极探索金融制度型开放。然而,当前推进金融高水平开放面临一些现实困境,如全球美元依赖型金融环境的外部约束、金融资本跨境流动存在结构性错配、金融机构的载体功能尚未完全释放和资本账户尚未完全开放等。因此,推进金融高水平开放的策略选择具体包括以下五个方面:形成境外人民币稳定供给机制以发挥货币在金融资本跨境流动中的基础作用、疏通金融机构载体职能发挥中的堵点以在吸引外资上提供更大便利、提升金融市场“管道式”开放能级以促进金融资本在更大合理范围内流动、优化境内外金融资本环境提高收益率以实现可持续发展,以及积极培育促进金融资本跨境自由流动与防范快速积累风险的规训环境。

关键词：金融开放金融资本金融资本跨境流动

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基于负刚度惯容型非线性能量汇的整星振动抑制

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动力学与控制学报 2024年第1期22卷 87-96页

作者：高原张振方勃沈阳航空航天大学航空宇航学院沈阳110136

本文将负刚度元件集成到惯容型非线性能量汇中构成负刚度惯容型非线性能量汇,并将此装置应用到整星结构,讨论其减振效果.基于最大幅值减振百分比展示了负刚度惯容型非线性能量汇的减振性能,并通过对比讨论了负刚度元件对惯容型非线性能... 详细信息

本文将负刚度元件集成到惯容型非线性能量汇中构成负刚度惯容型非线性能量汇,并将此装置应用到整星结构,讨论其减振效果.基于最大幅值减振百分比展示了负刚度惯容型非线性能量汇的减振性能,并通过对比讨论了负刚度元件对惯容型非线性能量汇减振性能的影响.最后讨论了负刚度惯容型非线性能量汇的参数影响及其优化.研究结果表明,作用于整星系统中的新型负刚度惯容型非线性能量汇具有很好的减振性能.

关键词：负刚度振动抑制惯容型非线性能量汇

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水工建筑物裂缝成因分析及防治研究

工程建设与设计 2024年第10期 221-223页

作者：方博中国电建集团中南勘测设计研究院有限公司长沙410000

在明确裂缝类型的基础上,分析了水工建筑物裂缝产生的主要原因,并从混凝土性能、结构设计、施工管理、裂缝检查处理等方面出发,强调了大体积混凝土裂缝防治的有效措施,有利于提高水工建筑物的设计与施工效果,减少质量和安全隐患。

关键词：水工建筑物裂缝成因分析裂缝防治工程病害

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圆锥面拟合的太赫兹发散角精密测量研究

计量学报 2024年第1期45卷 24-29页

作者：黎雅恬方波邬佳璐方灿蔡晋辉中国计量大学计量测试工程学院浙江杭州330018

针对太赫兹(THz)光束发散角精密测量问题,以单频连续波太赫兹源为研究对象,搭建了基于圆锥面拟合的太赫兹发散角测量装置。通过研究太赫兹光束的传播模式,分析其在空间上的光强分布特性,提出将太赫兹输出光束在远场范围内视作圆锥曲面,... 详细信息

针对太赫兹(THz)光束发散角精密测量问题,以单频连续波太赫兹源为研究对象,搭建了基于圆锥面拟合的太赫兹发散角测量装置。通过研究太赫兹光束的传播模式,分析其在空间上的光强分布特性,提出将太赫兹输出光束在远场范围内视作圆锥曲面,利用太赫兹探测器采集光斑图像,根据图像的边缘点坐标构建圆锥曲面,借助间接平差对边缘点数据做预处理并进行参数迭代与圆锥面拟合计算出光束发散角数值。结果表明,被测100 GHz的太赫兹源发散角为2.73°,相对扩展不确定度为3.8%(k=2)。

关键词：发散角测量太赫兹光束圆锥面拟合太赫兹探测器不确定度评定