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Real-time transition dynamics and stability of chipscale dispersion-managed frequency microcombs

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Light(Science & Applications) 2020年第1期9卷 1520-1529页

作者： Yongnan Li Shu-Wei Huang Bowen Li Hao Liu Jinghui Yang Abhinav Kumar Vinod Ke Wang Mingbin Yu dim-lee kwong Hui-Tian Wang Kenneth Kin-Yip Wong Chee Wei Wong Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory University of CaliforniaLos AngelesCA 90095USA School of Physics and The MOE Key Laboratory of Weak Light Nonlinear Photonics Nankai UniversityTianjinChina Department of Electrical Computer and Energy EngineeringUniversity of Colorado BoulderBoulderCO 80309USA Department of Electrical and Electronic Engineering The University of Hong KongHong KongChina Institute of Microelectronics A*STARSingapore 117865Singapore

Femtosecond mode-locked laser frequency combs have served as the cornerstone in precision spectroscopy,alloptical atomic clocks,and measurements of ultrafast *** frequency microcombs based on nonlinear microresonators have been examined,exhibiting remarkable precision approaching that of laser frequency combs,on a solid-state chip-scale platform and from a fundamentally different physical *** recent successes,to date,the real-time dynamical origins and high-power stabilities of such frequency microcombs have not been fully ***,we unravel the transitional dynamics of frequency microcombs from chaotic background routes to femtosecond mode-locking in real time,enabled by our ultrafast temporal magnifier metrology and improved stability of dispersion-managed dissipative *** our dispersion-managed oscillator,we further report a stability zone that is more than an order-of-magnitude larger than its prior static homogeneous counterparts,providing a novel platform for understanding ultrafast dissipative dynamics and offering a new path towards high-power frequency microcombs.

关键词： dispersion stability dynamics

Stimulated generation of deterministic platicon frequency microcombs

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Photonics Research 2022年第8期10卷 1877-1885页

作者： HAO LIU SHU-WEI HUANG WENTING WANG JINGHUI YANG MINGBIN YU dim-lee kwong PIERRE COLMAN CHEE WEI WONG Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory University of California Los AngelesLos AngelesCalifornia 90095USA Department of Electrical Computerand Energy EngineeringUniversity of Colorado BoulderBoulderColorado 80309USA Institute of Microelectronics SingaporeSingapore Universitéde Bourgogne Franche-Comté ICBUMR CNRS 6303DijonFrance

Dissipative Kerr soliton generation in chip-scale nonlinear resonators has recently observed remarkable advances,spanning from massively parallel communications, to self-referenced oscillators, and to dual-comb *** working in the anomalous dispersion regime, unique driving protocols and dispersion in these nonlinear resonators have been examined to achieve the soliton and soliton-like temporal pulse shapes and coherent frequency comb generation. The normal dispersion regime provides a complementary approach to bridge the nonlinear dynamical studies, including the possibility of square pulse formation with flattop plateaus, or *** we report observations of square pulse formation in chip-scale frequency combs through stimulated pumping at one free spectral range and in silicon nitride rings with +55 fs~2∕mm normal group velocity *** of the platicon frequency comb via a varied sideband modulation frequency is examined in both spectral and temporal measurements. Determined by second-harmonic autocorrelation and cross correlation, we observe bright square platicon pulse of 17 ps pulse width on a 19 GHz flat frequency comb. With auxiliary-laser-assisted thermal stabilization, we surpass the thermal bistable dragging and extend the mode-locking access to narrower 2 ps platicon pulse states, supported by nonlinear dynamical modeling and boundary limit discussions.

关键词： pumping soliton dispersion

Real-time dynamics and cross-correlation gating spectroscopy of free-carrier Drude slow-light solitons

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Light(Science & Applications) 2017年第1期6卷 729-736页

作者： Heng Zhou Shu-Wei Huang Xiujian Li James F McMillan Chi Zhang Kenneth Kin-Yip Wong Mingbin Yu Guo-Qiang Lo dim-lee kwong Kun Qiu Chee Wei Wong Key Lab of Optical Fiber Sensing and Communication Networks University of Electronic Science and Technology of ChinaChengdu 611731China Optical Nanostructures Laboratory Columbia UniversityNew YorkNY 10027USA Mesoscopic Optics and Quantum Electronics Laboratory University of CaliforniaLos AngelesCA 90095USA College of Science National University of Defense TechnologyChangshaHunan 410073China Department of Electrical and Electronic Engineering The University of Hong KongHong KongChina Institute of Microelectronics Agency for ScienceTechnology and ResearchScience ParkⅡSingapore 117685Singapore

Optical solitons—stable waves balancing delicately between nonlinearities and dispersive effects—have advanced the field of ultrafast optics and dynamics,with contributions spanning from supercontinuum generation to soliton fission,optical event horizons,Hawking radiation and optical rogue waves,among ***,we investigate picojoule soliton dynamics in silicon slow-light,photonic-bandgap waveguides under the influence of Drude-modeled,free-carrier-induced nonlinear *** real-time and single-shot amplified dispersive Fourier transform spectroscopy simultaneously with high-fidelity cross-correlation frequency resolved optical gating at femtojoule sensitivity and femtosecond resolution,we examine the soliton stability limits,the soliton dynamics including free-carrier quartic slow-light scaling and acceleration,and the Drude electron–hole plasma-induced perturbations in the Cherenkov radiation and modulation *** real-time single-shot and time-averaged cross-correlation measurements are matched with our detailed theoretical modeling,examining the reduced group velocity free-carrier kinetics on solitons at the picojoule scale.

关键词： nonlinear kinetics optical solitons photonic bandgap materials

Effect of pipe installation and external load on buried steel pipe responses:Experimental and numerical investigations

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Underground Space 2024年第2期15卷 44-58页

作者： Yadong Zhang Ron Chik-kwong Wong Jianfeng Chen Wei Su Department of Civil Engineering Schulich School of EngineeringUniversity of CalgaryCalgaryAB T2N 1N4Canada Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

During pipe installation,compacting soil at pipe sides causes an initial pipe deformation which is known as the"peaking"***,in conventional pipe design codes,only pipe deformation caused by vertical overburden is considered while the"peaking"effect is *** this study,a full-scale test was conducted on a Grade X52 steel pipe with a diameter of 600 mm to investigate the impacts of both soil compaction and vertical overburden on pipe *** compaction and external load were found to elongate and shorten the vertical pipe diameter,***"peaking"effect was observed during the installation procedure accompanied by the highest pipe stress measured at the pipe ***,a two-dimensional finite element model was created and validated based on the calculated pipe stresses from the experimental study.A parametric study was performed thereafter to numerically study the impacts of soil water content,pipe wall thickness,compaction pressure,and lift thickness on pipe responses due to soil compaction and external *** increase in the"peaking"effect is observed with increasing soil water content and compaction pressure,while an increase in pipe wall thickness or lift thickness would cause a decrease in the"peaking"effect.

关键词： X52 steel Soil compaction External load Peaking effect Pipe deflection Soil arching

Effect of non-uniform swelling on coal multiphysics during gas injection: The triangle approach

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1362-1372页

作者： Yifan Huang Jishan Liu Yaoyao Zhao Derek Elsworth Yee-kwong Leong Department of Chemical Engineering School of EngineeringThe University of Western Australia35 Stirling HighwayWA 6009Australia State Key Laboratory of Coal Resources & Safe Mining China University of Mining& TechnologyBeijing100803China Department of Energy and Mineral Engineering G3 Centre and Energy InstituteThe Pennsylvania State UniversityUniversity ParkPA16802USA

In current dual porosity/permeability models,there exists a fundamental assumption that the adsorption-induced swelling is distributed uniformly within the representative elementary volume (REV),irrespective of its internal structures and transient ***,both internal structures and transient processes can lead to the non-uniform *** this study,we hypothesize that the non-uniform swelling is responsible for why coal permeability in experimental measurements is not only controlled by the effective stress but also is affected by the adsorption-induced *** propose a concept of the swelling triangle composed of swelling paths to characterize the evolution of the non-uniform swelling and serve as a core link in coupled multiphysics.A swelling path is determined by a dimensionless volumetric ratio and a dimensionless swelling *** swelling paths have the same start and end point,and each swelling path represents a unique swelling *** swelling path as the diagonal of the triangle represents the case of the uniform swelling while that as the two perpendicular boundaries represents the case of the localized *** paths of all intermediate cases populate inside the *** corresponding relations between the swelling path and the response of coal multiphysics are established by a non-uniform swelling *** define this method as the triangle approach and corresponding models as swelling path-based *** proposed concept and models are verified against a long-term experimental measurement of permeability and strains under constant effective *** results demonstrate that during gas injection,coal multiphysics responses have a close dependence on the swelling path,and that in both future experiments and field predictions,this dependence must be considered.

关键词： Transient process Heterogeneity Swelling triangle Swelling path Non-uniform swelling coefficient

Oxidative spirolactonisation for modular access of γ-spirolactones via a radical tandem annulation pathway

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Chinese Chemical Letters 2024年第10期35卷 249-252页

作者： Jindian Duan Xiaojuan Ding Pui Ying Choy Binyan Xu Luchao Li Hong Qin Zheng Fang Fuk Yee kwong Kai Guo College of Biotechnology and Pharmaceutical Engineering State Key Laboratory of Materials-Oriented Chemical EngineeringNanjing Tech UniversityNanjing 211816China Department of Chemistry and State Key Laboratory of Synthetic Chemistry The Chinese University of Hong KongHong KongChina

An oxidative annulation of 2-arylidene-1,3-indanediones with Meldrum's acid has been developed for the divergent syntheses of spirolactones with a spirocenter located at theγ-position with respect to the carbonyl *** heteroannulation protocol tolerates various functional groups and delivers moderate-to-good product ***,the reaction outcomes are exclusively controlled by the reaction oxidant/*** annulation strategy can also be executed in the flow system with decent product *** experiments revealed that the reaction proceeds via a radical tandem annulation pathway.

关键词： Spirolactonisation y-Spirolactones 2-Arylidene-1,3-indanediones Meldrum's acid Divergentsynthesis

The Influence of Information Technology Investment on the Organizational Performance:The Moderating Role of External Environment

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Proceedings of Business and Economic Studies 2024年第5期7卷 37-42页

作者： Zhilin Shi Simon Choong Mun kwong City University Malaysia Kuala Lumpur 55100Malaysia Binzhou Polytechnic Binzhou 256600Shandong ProvinceChina

In the information era,enterprises can enhance organizational performance through advanced information *** on the resource-based view,this paper examines the mechanism by which information technology(IT)investment influences organizational performance,with the external environment as a moderating *** 265 valid samples collected from agricultural enterprises in Shandong province,this study conducts an empirical test through partial least squares structural equation *** results demonstrate that IT investment has a significant positive effect on organizational performance,and the external environment significantly moderates the relationship between IT investment and organizational *** research contributes to a deeper understanding of the relationship between IT investment and organizational performance,enriches resource-based theory,expands the research framework on IT investment,and offers guidance for enterprises seeking sustainable growth.

关键词： IT investment Organizational performance External environment

Wastewater Surveillance Provides Spatiotemporal SARS-CoV-2 Infection Dynamics

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Engineering 2024年第9期40卷 70-77页

作者： Xiawan Zheng Kathy Leung Xiaoqing Xu Yu Deng Yulin Zhang Xi Chen Chung In Yau Kenny W.K.Hui Eddie Pak Ho-kwong Chui Ron Yang Hein Min Tun Gabriel Matthew Leung Joseph Tsz Kei Wu Malik Peiris Leo Lit Man Poon Tong Zhang Environmental Microbiome Engineering and Biotechnology Lab Center for Environmental Engineering ResearchDepartment of Civil EngineeringThe University of Hong KongHong Kong 999077China WHO Collaborating Centre for Infectious Disease Epidemiology and Control School of Public HealthLi Ka Shing Faculty of MedicineThe University of Hong KongHong Kong 999077China Laboratory of Data Discovery for Health Litd.(D24H) Hong Kong 999077China The University of Hong Kong-Shenzhen Hospital Hong Kong 999077China School of Public Health Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong 999077China HKU-Pasteur Research Pole The University of Hong KongHong Kong 999077China Drainage Services Department The Government of the Hong Kong Special Administrative RegionHong Kong 999077China Environmental Protection Department The Government of the Hong Kong Special Administrative RegionHong Kong 999077China The Jockey Club School of Public Health and Primary Care Faculty of MedicineThe University of Hong KongHong Kong 999077China

Wastewater surveillance(WWS)can leverage its wide coverage,population-based sampling,and high monitoring frequency to capture citywide pandemic trends independent of clinical *** we conducted a nine months daily WWS for severe acute respiratory syndrome coronavirus 2(SARSCoV-2)from 12 wastewater treatment plants(WWTPs),covering approximately 80%of the population,to monitor infection dynamics in Hong Kong,*** found that the SARS-CoV-2 virus concentration in wastewater was correlated with the daily number of reported cases and reached two pandemic peaks three days earlier during the study *** addition,two different methods were established to estimate the prevalence/incidence rates from wastewater *** estimated results from wastewater were consistent with findings from two independent citywide clinical surveillance programmes(rapid antigen test(RAT)surveillance and serology surveillance),but higher than the cases number reported by the Centre for Health Protection(CHP)of Hong Kong,***,the effective reproductive number(R_(t))was estimated from wastewater measurements to reflect both citywide and regional transmission *** findings demonstrate that large-scale intensive WWS from WWTPs provides cost-effective and timely public health information,especially when the clinical surveillance is inadequate and *** approach also provides insights into pandemic dynamics at higher spatiotemporal resolutions,facilitating the formulation of effective control policies and targeted resource allocation.

关键词： SARS-CoV-2 Wastewater surveillance Prevalence Effective reproductive number

On Product-Cordial Index Sets and Friendly Index Sets of 2-Regular Graphs and Generalized Wheels

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Acta Mathematica Sinica,English Series 2012年第4期28卷 661-674页

作者： Harris kwong Sin Min lee Ho Kuen NG Department of Mathematical Science SUNY Fredonia Department of Computer Science San Jose State University Department of Mathematics San Jose State University

A vertex labeling f ： V →Z2 of a simple graph G = （V, E） induces two edge labelings The friendly index set and the product-cordial index set of G are defined as the setsf is friendly}. In this paper we study and determine the connection between the friendly index sets and product-cordial index sets of 2-regular graphs and generalized wheel graphs.

关键词： Friendly index set product cordial index set 2-regular graphs generalized wheels