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Ultralow-phase-noise and broadband frequency-hopping coupled optoelectronic oscillator under quiet point operation

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Photonics Research 2024年第8期12卷 1785-1793页

作者： HUI liu MINGYANG GUO TIAN ZHANG jian DAI kun XU State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Advancements in microwave photonics have yielded novel approaches for generating high-purity microwave *** these,optoelectronic oscillators(OEOs)and coupled optoelectronic oscillators(COEOs)have demonstrated the capability to generate frequency-independent microwaves with exceptionally low phase ***,the tunability of the oscillators is rather limited due to the necessity for narrowband electronic bandpass filters,presenting challenges in achieving both wide and rapid tuning ***,we present a COEO featuring ultralow phase noise,flexible tuning capability,and high *** is achieved through a quiet point(QP)-operated harmonic mode-locked fiber laser,which effectively mitigates optical amplifier noise and supermode competition,thus significantly diminishing the necessity for ultra-narrow electronic *** to the liberated tuning ability,we present an oscillator that can be tuned from 2 GHz to 18 GHz,with phase noise as low as-140 d Bc/Hz at 10 k Hz under the QP *** then illustrate the practical application of the proposed oscillator in generating frequency-hopping signals with consistent spurious modes less than-85 d Bc,absolute phase noise below-135 d Bc/Hz at 10 k Hz,hopping resolution of 1.25 MHz,and fractional frequency stability below 6.1×10^(-12)at 1 s averaging time when locked to a *** presented COEO structure emerges as a compelling solution for agile and low-noise microwave sources in advanced wireless communication and radar systems.

关键词： optoelectronic tuning amplifier

Direct shear tests of coarse-grained fillings from high-speed railway subgrade in cold regions

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Research in Cold and Arid Regions 2017年第3期9卷 236-242页

作者： Qing Zhi Wang jian kun liu jian Hong Fang An Hua Xu School of Civil Engineering Beijing Jiaotong University Qinghai Research Institute of Transportation

In order to study the shear behavior of coarse-grained fillings taken from the subgrade bottom layer of a cold region high-speed railway,large scale direct shear tests were conducted with different normal pressures,water contents and *** results indicate that the relationship between shear displacement and shear stress changed from strain-softening at lower normal pressures to strain-hardening at higher normal pressures,in both unfrozen and frozen *** phenomenon was mainly due to the shear dilatation deformation *** shear displacement-shear stress curves show similar ***,the shear stress rapidly increased and there was not an increment in the shear displacement during the initial stage of the shear process in the frozen *** both the unfrozen or frozen states at the same water contents,the shear strength increased with increasing normal pressure.

关键词： coarse-grained fillings large scale direct test shear displacement-shear stress curve shear strength

Deformation properties of chloride saline soil under action of a low-temperature environment and different loads

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Research in Cold and Arid Regions 2017年第3期9卷 307-311页

作者： Yu Zhang jian kun liu jian Hong Fang An Hua Xu Lanzhou Jiaotong University School of Traffic and Transportation Beijing Jiaotong University School of Civil Engineering Qinghai Research Institute of Transportation

To find the deformation properties of chloride saline soil under the influence of a low temperature environment and different loads,two types of chloride saline soil were selected and their deformation process was tested in the laboratory and analyzed during the cooling process in the sensitive cryogenic temperature *** research results show that high-chloride-salt saline soil underwent little volume change under the no-load condition during the cooling *** staticload and dynamic-load conditions,different degrees of settlement deformation occurred;throughout the entire cooling process,another chloride saline soil with a high proportion of sulfate salt underwent volume expansion under no-load and static-load *** the no-load condition,a certain degree of settlement deformation *** properties were evaluated at different time points during the cooling process for two kinds of chloride saline ***,deformation characteristics of chloride saline soil were analyzed from the perspective of salt type and crystallization variation under the action of a low-temperature environment and different loads.

关键词： saline soil low temperature loads deformation cooling process

Atomic layer deposition in advanced display technologies:from photoluminescence to encapsulation

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International Journal of Extreme Manufacturing 2024年第2期6卷 65-82页

作者： Rong Chen kun Cao Yanwei Wen Fan Yang jian Wang Xiao liu Bin Shan State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiPeople’s Republic of China State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiPeople’s Republic of China

Driven by the growing demand for next-generation displays,the development of advanced luminescent materials with exceptional photoelectric properties is rapidly accelerating,with such materials including quantum dots and phosphors,***,the primary challenge preventing the practical application of these luminescent materials lies in meeting the required durability *** layer deposition(ALD)has,therefore,been employed to stabilize luminescent materials,and as a result,flexible display devices have been fabricated through material modification,surface and interface engineering,encapsulation,cross-scale manufacturing,and *** addition,the appropriate equipment has been developed for both spatial ALD and fluidized ALD to satisfy the low-cost,high-efficiency,and high-reliability manufacturing *** strategic approach establishes the groundwork for the development of ultra-stable luminescent materials,highly efficient light-emitting diodes(LEDs),and thin-film ***,this significantly enhances their potential applicability in LED illumination and backlighted displays,marking a notable advancement in the display industry.

关键词： atomic layer deposition display luminescent encapsulation

Elastoplastic behavior of frozen sand-concrete interfaces under cyclic shear loading

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第9期23卷 683-703页

作者： jian CHANG jian-kun liu Ya-li LI Qi WANG Zhong-hua HAO School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China School of Civil Engineering Sun Yat-sen UniversityZhuhai 519082China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China

The resilient modulus,accumulated plastic strain,peak shear stress,and critical shear stress are the elastoplastic behaviors of frozen sand–concrete interfaces under cyclic shear *** reflect the bearing capacity of buildings(*** railways)in both seasonal frozen and permafrost *** study describes a series of direct shear experiments conducted on frozen sand–concrete *** results indicated that the elastoplastic behaviors of frozen sand–concrete interfaces,including the resilient modulus,accumulated plastic strain,and shear strength,are influenced by the boundary conditions(constant normal loading and constant normal height),initial normal stress,negative temperature,and cyclic-loading *** resilient modulus was significantly correlated with the initial normal stress and negative temperature,but not with the cyclic-loading amplitude and loading *** accumulated plastic shear strain increased when the initial normal stress and cyclic-loading amplitude increased and the temperature ***,the accumulated plastic shear strain increment decreased when the loading cycles *** accumulated direction also varied with changes in the initial normal stress,negative temperature,and cyclic-loading *** peak shear stress of the frozen sand–concrete interface was affected by the initial normal stress,negative temperature,cyclic-loading amplitude,and boundary ***,a correlation was observed between the critical shear stress and the initial normal stress and boundary *** peak shear stress was higher,and the critical shear stress was lower under the constant normal height boundary *** on the results,it appears that the properties of frozen sand–concrete interfaces,including plastic deformation properties and stress strength properties,are influenced by cyclic shear *** results provide valuable information for the investigation of constitutive models of f

关键词： Frozen sand-concrete interface Cyclic direct shear test Elastoplastic behavior Direction of accumulated plastic strain Boundary condition

Bichromatically pumped artificial cnoidal wave breathers in optical microresonators

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Photonics Research 2024年第7期12卷 1464-1477页

作者： YIRAN GAO jian DAI ZHONGHAN WU ANNI liu TIAN ZHANG WEI SUN JUNQIU liu kun XU State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China School of Communication Engineering Hangzhou Dianzi UniversityHangzhou 310018China International Quantum Academy Shenzhen 518048China Hefei National Laboratory University of Science and Technology of ChinaHefei 230026China

Breathers are localized structures that undergo a periodic oscillation in their duration and amplitude. Optical microresonators, benefiting from their high-quality factor, provide an ideal test bench for studying breathing phenomena. In a monochromatically pumped microresonator system, intrinsic breathing instabilities are widely observed in the form of temporal dissipative Kerr solitons which only exist in the effectively red-detuned ***, we demonstrate a novel bichromatic pumping scheme to create compulsive breathing microcombs via respectively distributing two pump lasers at the effectively blue-and red-detuned sides of a single *** experimentally discover the artificial cnoidal wave breathers and molecular crystal-like breathers in a photonic chip-based silicon nitride microresonator and theoretically describe their intriguing temporal dynamics based on the bichromatic pumping Lugiato–Lefever equation. In particular, the corresponding breathing microcombs exhibit diverse comb line spacing ranging from 2 to 17 times the free spectral range of the *** discovery not only provides a simple yet robust method to harness microcombs with reconfigurable comb line spacing but also reveals a new class of breathing waves in driven dissipative nonlinear systems.

关键词： pumped resonator pumping

Generalized Inverses and Units in a Unitary Ring

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Acta Mathematica Sinica,English Series 2024年第4期40卷 1000-1014页

作者： Yu kun ZHOU jian Long CHEN School of Mathematics Southeast UniversityNanjing 210096P.R.China

Let R be a unitary ring and a,b∈R with ab=*** find the 2/3 property of Drazin invertibility:if any two of a,b and a+b are Drazin invertible,then so is the third ***,we combine the 2/3 property of Drazin invertibility to characterize the existence of generalized inverses by means of *** applications,the need for two invertible morphisms used by You and Chen to characterize the group invertibility of a sum of morphisms is reduced to that for one invertible morphism,and the existence and expression of the inverse along a product of two regular elements are obtained,which generalizes the main result of Mary and Patricio(2016)about the group inverse of a product.

关键词： Leftπ-regular element stronglyπ-regular element group inverse Drazin inverse inverse along an element

Experimental study of the dynamic behavior of high-grade highway-subgrade soil in a seasonally frozen area

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Research in Cold and Arid Regions 2017年第3期9卷 289-296页

作者： Hong Huan Cui Yu Tao Ma jian kun liu Zhi Yang Wang School of Civil Engineering Hebei University of Architecture School of Civil Engineering Beijing Jiaotong University

Regarding the freezing damage of high-grade highway subgrade in seasonally frozen area,the thesis explores the effect on the dynamic behavior of subgrade soil under freeze–thaw cycles and draws the change law of parameters(including dynamic strength,dynamic cohesion,and internal friction angle;and dynamic elastic modulus)of high-grade highway-subgrade soil with the number of freeze–thaw *** aims to provide the reference for operation and maintenance of a high-grade ***:(1)Dynamic strength tends to decline evidently after freeze–thaw cycles,with 60%~70%decline after three cycles,and remains stable after five to seven cycles.(2)With the number of freeze–thaw cycles increasing,the internal friction angle fluctuates within a certain range without an obvious change law,only presenting the tendency of dropping *** dynamic cohesion declines obviously,about 20%~40%after seven freeze–thaw cycles,and then tends to be stable.(3)With the number of freeze-thaw cycles increasing,the dynamic elastic modulus and maximum dynamic elastic modulus are inclined to decrease *** five freeze–thaw cycles,the former declines 30%~40%and then remains ***,the latter falls 20%~40%.

关键词： seasonally frozen area freeze-thaw cycle dynamic behavior dynamic triaxial test high-grade highway-subgrade soil

季节性冻土区光伏支架螺旋桩抗冻拔试验研究（英文）

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2016年第7期17卷 512-524页

作者： Teng-fei WANG jian-kun liu Hua-gang ZHAO Ya-long SHANG Xiao-qiang liu School of Civil Engineering Beijing Jiaotong University North China Power Engineering Co. Ltd.of China Power Engineering Consulting Group

目的:基于相似性原理,模拟实际工况中的降温冻结过程;通过室内试验确定最优桩型,并推导冻拔量与冻深的定量关系。创新点:1.进行季节性冻土区螺旋桩的自由冻胀试验;2.根据相似性原理,在室内试验过程中调整冷端温度与几何尺寸以缩短冻结时... 详细信息

目的:基于相似性原理,模拟实际工况中的降温冻结过程;通过室内试验确定最优桩型,并推导冻拔量与冻深的定量关系。创新点:1.进行季节性冻土区螺旋桩的自由冻胀试验;2.根据相似性原理,在室内试验过程中调整冷端温度与几何尺寸以缩短冻结时间;3.推导得到6种桩型冻拔量与冻结深度的定量关系。方法:1.通过相似性原理确定试验条件,模拟实际工况中的降温冻结过程;2.观测此过程中5种螺旋桩型的温度场、冻拔量和土压力随时间的变化规律,并设置一组光滑桩作为对比;3.根据冻拔量大小选取最优桩型,并推导冻拔量与冻深的定量关系。结论:1.螺旋桩冻拔量小于光滑桩,验证了螺旋桩抗冻拔的有效性;采用不同土样有相同规律。2.冻深达到0.9 m的季冻区,双螺旋大叶片桩抗冻拔效果最好;螺旋叶片建议设置在非冻区;冻拔量大小关系为:双螺旋大叶片桩<半螺旋大叶片桩<半螺旋小叶片桩<双螺旋小叶片桩<全螺旋桩<光滑桩。3.得到6种桩型冻拔量与冻深的线性关系。4.土中水开始冻结时土压力增大,含冰量稳定后土压力变化很小。

关键词：季节性冻土区螺旋桩冻胀相似性原理冻拔