Electro-Optics and Its Applications in Domain-Inverted Optical Superlattice

Lijun Chen,Xianfeng Chen,Jianhong hi,Yuping Chen,Yuxing Xia 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.2

We demonstrate an electro-optic ˇSolc-type wavelength filter in periodically poled lithium niobate (PPLN). ˇSolc-type transmission spectrum is observed experimentally in a PPLN with four periods from 20.2 μm to 20.8 μm. Modulation of transmission power of the filter can be realized by applying electric fields along Y -axis of PPLN. It is observed that the wavelength can also be tuned by temperature. Furthermore, we report on a theoretical analysis for the narrowband multiplewavelength filter in aperiodic optical superlattice (AOS). The sequences of the opposite domains in AOS are optimized to realize the prescribed multiple-wavelength filtering by using a simulatedannealing (SA) algorithm. The influences of domain errors, as well as the working temperature, on the performance of the filters are also studied.

Research on Finite-Time Consensus of Multi-Agent Systems

Chen, Lijun,Zhang, Yu,Li, Yuping,Xia, Linlin Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.2

In order to ensure second-order multi-agent systems (MAS) realizing consensus more quickly in a limited time, a new protocol is proposed. In this new protocol, the gradient algorithm of the overall cost function is introduced in the original protocol to enhance the connection between adjacent agents and improve the moving speed of each agent in the MAS. Utilizing Lyapunov stability theory, graph theory and homogeneity theory, sufficient conditions and detailed proof for achieving a finite-time consensus of the MAS are given. Finally, MAS with three following agents and one leading agent is simulated. Moreover, the simulation results indicated that this new protocol could make the system more stable, more robust and convergence faster when compared with other protocols.

Simulation Study on Measuring Pulverized Coal Concentration in Power Plant Boiler

Chen, Lijun,Wang, Yang,Su, Cheng Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.1

During thermal power coal-fired boiler operation, it is very important to detect the pulverized coal concentration in the air pipeline for the boiler combustion stability and economic security. Because the current measurement methods used by power plants are often involved with large measurement errors and unable to monitor the pulverized coal concentration in real-time, a new method is needed. In this paper, a new method based on microwave circular waveguide is presented. High Frequency Electromagnetic Simulation (HFSS) software was used to construct a simulation model for measuring pulverized coal concentration in power plant pipeline. Theoretical analysis and simulation experiments were done to find the effective microwave emission frequency, installation angle, the type of antenna probe, antenna installation distance and other important parameters. Finally, field experiment in Jilin Thermal Power Plant proved that with selected parameters, the measuring device accurately reflected the changes in the concentration of pulverized coal.

Performance of Tunnel Feet-Lock Pipe (TFP) in Sharing Vertical Foundation Load

Lijun Chen,Jianxun Chen,Yao Li,Yanbin Luo,Yongjun Mu,Taotao Hu,Chuanwu Wang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.3

During the tunnel construction in soft ground, the insufficient bearing capacity of tunnel foundation usually causes a series of settlement problems. Tunnel feet-lock pipe (TFP) has been widely used to take the vertical load acting at the foundation of a tunnel foot. However, the detailed bearing performance of TFP is still not clear, and there is a lack of quantitative research. In this paper, a simple analytical approach is adopted to evaluate the performance of the TFP, and the main parameters affecting the supporting performance of the TFP are analyzed. The results show that the ϕ42 − ϕ140 TFP with the angle of 10° can take 3.8% −40.4% of vertical load. TFP has an effective length of 1.7 m − 2.8 m, which is related to the relative stiffness between the TFP and the stratum. With the increase of the installation angle, the TFP shares more vertical load. This trend is more obvious when the angle of the TFP is greater than 20°. If the proportion coefficient of the subgrade reaction coefficient is doubled, the vertical load shared by the TFP can be increased by 34% − 38%. For every 10 cm increase in overbreak behind the steel rib, the vertical load shared by TFP is reduced by 16%.

The sense of localization of tourism language

Chen LIJUN(陈丽君) 세계문화관광학회 2011 Conference Proceedings Vol.12 No.-

This paper analyzes the status of the sense of weak localization of tourism language considers that the weakened sense of localization of tourism language brought the most immediate consequence: reduce the types of language of tour places and the tourists don't get the novelty experience. proposes to formulate the science language planning to deal with the tourism language between internationalization and localization and regard experience tourism as an opportunity mining dialect culture so that the tourism language will maintain localization while international. 旅游语言存在本土化意识弱的现状 本土化意识减弱带来的最直接的后果就是放游地语言种类减 少和旅游者得不到异地体验的新鲜感.提出要制订科学的语言规划来处理旅游语言的国际化和本土化关系 以体验式放旅游为契机 挖掘方言文化 使旅游语言在国际化的同时保持本土化.

Research on Finite-time Consensus of Multi-agent Systems

Lijun Chen,Yu Zhang,Yuping Li,Linlin Xia 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.2

In order to ensure second-order multi-agent systems (MAS) realizing consensus more quickly in a limited time, a new protocol is proposed. In this new protocol, the gradient algorithm of the overall cost function is introduced in the original protocol to enhance the connection between adjacent agents and improve the moving speed of each agent in the MAS. Utilizing Lyapunov stability theory, graph theory and homogeneity theory, sufficient conditions and detailed proof for achieving a finite-time consensus of the MAS are given. Finally, MAS with three following agents and one leading agent is simulated. Moreover, the simulation results indicated that this new protocol could make the system more stable, more robust and convergence faster when compared with other protocols.

Simulation study on measuring pulverized coal concentration in power plant boiler

Lijun Chen,Yang Wang,Cheng Su 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.1

During thermal power coal-fired boiler operation, it is very important to detect the pulverized coalconcentration in the air pipeline for the boiler combustion stability and economic security. Because the currentmeasurement methods used by power plants are often involved with large measurement errors and unable tomonitor the pulverized coal concentration in real-time, a new method is needed. In this paper, a new methodbased on microwave circular waveguide is presented. High Frequency Electromagnetic Simulation (HFSS)software was used to construct a simulation model for measuring pulverized coal concentration in power plantpipeline. Theoretical analysis and simulation experiments were done to find the effective microwave emissionfrequency, installation angle, the type of antenna probe, antenna installation distance and other importantparameters. Finally, field experiment in Jilin Thermal Power Plant proved that with selected parameters, themeasuring device accurately reflected the changes in the concentration of pulverized coal.

Risk Factors for Poor Outcomes Following Minimally Invasive Discectomy: A Post Hoc Subgroup Analysis of 2-Year Follow-up Prospective Data

Zihao Chen,Lei He,Lijun Huang,Zhongyu Liu,Jianwen Dong,Bin Liu,Ruiqiang Chen,Liangming Zhang,Peigen Xie,Limin Rong 대한척추신경외과학회 2022 Neurospine Vol.19 No.1

Objective: A post hoc subgroup analysis of prospectively collected data from a randomized controlled trial was conducted to identify risk factors related to poor outcomes in patients who underwent minimally invasive discectomy. Methods: Patients were divided into satisfied and dissatisfied subgroups based on Oswestry Disability Index (ODI), visual analogue scale (VAS) back pain score (VAS-back) and leg pain score (VAS-leg) at short-term and midterm follow-up according to the patient acceptable symptom state threshold. Demographic characteristics, radiographic parameters, and clinical outcomes between the satisfied and dissatisfied subgroups were compared using univariate and multivariate analysis. Results: A total of 222 patients (92.1%) completed 2-year follow-up, and the postoperative ODI, VAS-back, and VAS-leg were significantly improved after surgery as compared to preoperatively. Multivariate analysis indicated older age (p = 0.026), lateral recess stenosis (p = 0.046), and lower baseline ODI (p = 0.027) were related to poor short-term functional improvement. Higher baseline VAS-back (p = 0.048) was associated with poor short-term relief of back pain, while absence of decreased sensation (p = 0.019) and far-lateral disc herniation (p = 0.004) were associated with poorer short-term relief of leg pain. Lumbar facet joint osteoarthritis was identified as a risk factor for poor functional improvement (p = 0.003) and relief of back pain (p = 0.031). Disc protrusion (p = 0.036) predicted poorer relief of back pain at midterm follow-up. Conclusion: In this study, several factors were identified to be predictive of poor surgical outcomes following minimally invasive discectomy. (ClinicalTrials.gov number: NCT01997086).

Failure Mechanisms and Modes of Tunnels in Monoclinic and Soft-Hard Interbedded Rocks: A Case Study

Jianxun Chen,Weiwei Liu,Lijun Chen,Yanbin Luo,Yao Li,Haijiang Gao,Daochuan Zhong 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4

The issue of large deformation mechanism in soft rock tunnels has puzzled tunnel scholars for decades. Previous studies have not evolved a clear and common understanding. Therefore, detailed on-site measurement, full investigation and statistical analysis have been conducted on the instability and failure of Muzhailing Tunnel since its construction, whose length is beyond 15 km. The study aims at systematically analyzing the failure mechanisms and modes of Muzhailing Tunnel in monoclinic and soft-hard interbedded rock strata. Study results show that the angle between strata strike and tunnel axis greatly determines the magnitude of deformation, the dip direction significantly controls the bias direction and maximum deformation direction, and the dip angle deeply affects the deformation form. The failure modes of surrounding rock mainly include four types: spalling and overturning failure, bending failure, shear slip failure and buckling failure. Large deformation characteristics are summarized from six aspects: failure form, groundwater, sensitivity to influencing factors, deformation degree, deformation speed and deformation duration. The instability modes of primary lining include in-plane (transverse) instability and out-plane (longitudinal) instability. Finally, the causes of large deformation are analyzed from geological, structural, engineering and human factors.

Development and Application of High-Performance Grouting Materials for Anchoring Pipe in Soft Rock Tunnel

Li-xin Zhang,Jianxun Chen,Lijun Chen,Yanbin Luo,Weiwei Liu,Fangfang Dong,Hao Chen,Hao-yang Zhu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.10

A high-performance grouting material is proposed to enhance the support effect of anchoring pipes in soft rock mass tunnels in this paper. Through mix proportion and strength tests, the initial setting time, compressive strength, and flowability of the grouting material were determined. Furthermore, based on grouting and pulling tests, the recommended parameters of the anchoringpipe were proposed. The results show that pure cement paste is an ideal grouting material for on-site application, demonstrating excellent anchoring, fluidity, high strength, and rapid hardening. Under optimal conditions of water-cement ratio at 0.46 and retarder proportion at 0.4‰, the initial settling time and the compressive strength of the grouting material are approximately 45 minutes and 28.5 MPa within 4 hours, respectively. The anchoring force of an anchoring pipe with a length of 6 m and a diameter of 76 mm can reach 448.9 kN within the same period. A field test involving anchoring pipes and pure cement paste was conducted during tunnel construction, resulting in a substantial reduction of maximum settlement and convergence of the tunnel by 57.53% and 40.48%, respectively. These results demonstrate the effectiveness