5G Converged Cell-Less Communications in Smart Cities

Han, Tao,Ge, Xiaohu,Wang, Lijun,Kwak, Kyung Sup,Han, Yujie,Liu, Xiong Institute of Electrical and Electronics Engineers 2017 IEEE communications magazine Vol.55 No.3

<P>Ubiquitous information service converged by different types of heterogeneous networks is one of fundamental functions for smart cities. Considering the deployment of 5G ultra-dense wireless networks, 5G converged cell-less communication networks are proposed to support mobile terminals in smart cities. To break obstacles of heterogeneous wireless networks, the 5G converged cell-less communication network is vertically converged in different tiers of heterogeneous wireless networks and horizontally converged in celled architectures of base stations/access points. Moreover, the software defined network controllers are configured to manage the traffic scheduling and resource allocation in 5G converged cell-less communication networks. Simulation results indicate the coverage probability and the energy saving at both base stations and mobile terminals are improved by the cooperative grouping scheme in 5G converged cell-less communication networks.</P>

Probabilistic damage detection of structures with uncertainties under unknown excitations based on Parametric Kalman filter with unknown Input

Lijun Liu,Han Su,Ying Lei 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.6

System identification and damage detection for structural health monitoring have received considerable attention. Various time domain analysis methodologies based on measured vibration data of structures have been proposed. Among them, recursive least-squares estimation of structural parameters which is also known as parametric Kalman filter (PKF) approach has been studied. However, the conventional PKF requires that all the external excitations (inputs) be available. On the other hand, structural uncertainties are inevitable for civil infrastructures, it is necessary to develop approaches for probabilistic damage detection of structures. In this paper, a parametric Kalman filter with unknown inputs (PKF-UI) is proposed for the simultaneous identification of structural parameters and the unmeasured external inputs. Analytical recursive formulations of the proposed PKF-UI are derived based on the conventional PKF. Two scenarios of linear observation equations and nonlinear observation equations are discussed, respectively. Such a straightforward derivation of PKF-UI is not available in the literature. Then, the proposed PKF-UI is utilized for probabilistic damage detection of structures by considering the uncertainties of structural parameters. Structural damage index and the damage probability are derived from the statistical values of the identified structural parameters of intact and damaged structure. Some numerical examples are used to validate the proposed method

Economic Dispatch of Multi Region Electric and Heat Energy System Using Two Stage Demand Response for Better Integration of Wind Power

Yang Lijun,Han Qi,Li Xueping 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5

The stochastic fl uctuation characteristics of wind power and the operation mode of ‘determined power by heat’ of the combined heat and power unit are the main reasons for the large amount of abandoning wind during the winter heating period in the ‘Three-North’ regions of China. In order to suppress wind power fl uctuations and improve the self-regulation ability, the heat pipe network model at unit side is proposed in this paper. On this basis, the price demand respond is introduced at load side to reduce the scheduling pressure caused by the uncertainty of wind power. Firstly, the day ahead consumption model of segment electricity price demand response is developed based on the day ahead wind power prediction; Furthermore, according to the results of the intraday wind power prediction, the intraday electricity price with wind variation demand response is introduced to guide the secondary load response. Thus, a two-stage demand response economic dispatch model of multi-region electric and heat system is established in this paper. Example analysis shows the eff ectiveness and superiority of the proposed dispatching model.

<i>Arabidopsis</i> glucan synthase-like 10 functions in male gametogenesis

Huang, Lijun,Chen, Xiong-Yan,Rim, Yeonggil,Han, Xiao,Cho, Won Kyong,Kim, Seon-Won,Kim, Jae-Yean Elsevier 2009 Journal of plant physiology Vol.166 No.4

<P><B>Summary</B></P><P>Callose or <I>β</I>-1,3-glucan performs multiple functions during male and female gametophyte development. Callose is synthesized by 12 members of the glucan synthase-like (GSL) gene family in <I>Arabidopsis thaliana</I>. To elucidate the biological roles of <I>Arabidopsis</I> GSL family members during sexual development, we initiated a reverse genetic approach with T-DNA insertional mutagenesis lines. We screened T-DNA insertion lines for all members of the GSL gene family and detected homozygous mutant seedlings for all members except <I>GSL10</I>. Three independent alleles in <I>GSL10</I>, <I>gsl10-1</I>, <I>gsl10-3</I> and <I>gsl10-4</I> showed distorted segregation (1:1:0) of T-DNA inserts rather than Mendelian segregation (1:2:1). By genetic analysis through reciprocal cross, we determined that <I>gsl10</I> pollen could not be transmitted to descendent. The mutant pollen of <I>GSL10</I>/<I>gsl10</I> plants at tetrad and microspore stages were not different from that of wild type, suggesting that <I>GSL10</I> is not essential for normal microspore growth. Analysis of <I>GSL10</I>/<I>gsl10</I> hemizygous pollen during development revealed abnormal function in asymmetric microspore division. <I>gsl10</I> mutant microspores failed to enter into mitosis. Unlike the previously described functions of <I>GSL1</I>, <I>GSL2</I> and <I>GSL5</I>, <I>GSL10</I> involves an independent process of pollen development at the mitotic division stage.</P>

The Split-Permeation Grouting Mechanism of Loose and Broken Coal Rock Masses considering the Temporal and Spatial Characteristics of Slurry Viscosity

Hexuan Zhu,Lijun Han,Qingbin Meng,Jun Liu,Lingdong Meng,Wenlong Dong 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

Quick-setting grout has time-varying characteristics, and the space porosity of the injected medium changes after being grouted. The above two points need to be considered when loose and broken coal rock masses are grouted with rapid-setting grout. In other words, the coupling effect of the slurry-coal rock mass causes the slurry to exhibit the temporal and spatial characteristics of slurry viscosity (TSCSV). Based on the Bingham fluid constitutive model, a capillary group model with a linear increase in diameter was created, and a one-dimensional penetration grout diffusion model was established considering the TSCSV. The one-dimensional visualization splitting-permeation grout diffusion simulation test system was designed to obtain the space porosity of the broken coal rock mass under different final grouting pressures to obtain the law of the changes in grouting pressure and diffusion height with time under the condition of a fixed grouting rate. Furthermore, the mechanism of splitting-permeation grouting in loose and broken coal rock masses is analysed in depth considering the TSCSV. The results showed that the space porosity of coal rock masses increases linearly. In addition, the calculated value of the slurry diffusion distance was 0.93 − 1.1 times the experimental value considering the TSCSV. The calculated value was in good agreement with the experimental value. The calculated value of the final pressure of orifice grouting was approximately 1.5 times the test value without considering the unevenness of the space porosity distribution (USPD). The grouting pressure was overestimated without considering the USPD. Therefore, the TSCSV of the quick-setting slurry should be fully considered in the grouting design.

Study on the Influence of Formation Temperature on the Water Absorption and Weathering of Swelling Rock in Marine Coal Mines

Lingdong Meng,Lijun Han,Hexuan Zhu,Wenlong Dong,Wei Li 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

To study the mechanisms and potential control measures for coal mine engineering safety hazards caused by swelling rock, water absorption experiments were performed under different temperature by using an independently developed rock water absorption test system. The swelling pressure, expansion amount and water absorption amount of specimens were monitored in real time. Nuclear magnetic resonance and uniaxial compression experiments were performed. The water absorption rate of the swelling rock specimens increases significantly with increasing water absorption time. The water absorption capacity of the specimens differs considerably under different temperatures. The water absorption curve can be divided into three stages: the severe stage, deceleration stage and equilibrium stage. The water absorption amount and water absorption rate are linearly related to temperature. The curve of the swelling pressure depicts a double peak shape. The expansion curve can also be divided into three stages. With increasing temperature, the expansion rate increases, and the time needed to achieve expansion stability is prolonged. There is a negative linear correlation between the uniaxial compressive strength and the moisture content. The higher the temperature is, the higher the moisture content. The increase in the rock porosity after water absorption is one of the important factors driving the strength attenuation.

Facile Synthesis of Flower-Like AgI/BiOBr Z-Scheme Nanocomposite with Enhanced Photocatalytic Activity for Degradation of 17α-Estradiol (EE2)

Lingxin Li,Han Li,Yanju Long,Shan Wang,Yu Chen,Sifeng Zhang,Lulu Wang,Lijun Luo,Fengzhi Jiang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.1

In the present work, a direct Z-scheme AgI/BiOBr heterojunction displaying improved photocatalytic activity was designed by a chemical bath deposition method. The obtained photocatalysts were systematically characterized through XRD, SEM, XPS, BET and UV-Vis diffuse reflectance spectroscopy. The synthesized AgI/BiOBr photocatalyst displayed superior photocatalytic performance in the case of 17α-ethinylestradiol (EE2), where 97.0% compound has been removed within 9 min of irradiation. The rate constant using AgI/BiOBr photo-catalyst was 16.0 and 138.7 times more than that of pure AgI and BiOBr, respectively. Furthermore, the photocatalytic mechanism was investigated. The results of this study indicated that AgI/BiOBr was a stable and efficient photocatalyst, with promising practical applications.

Experimental Study on the Mechanical Performance of Grouted Specimen with Composite Ultrafine Cement Grouts

Maolin Tian,Lijun Han,Qingbin Meng 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.1

An experimental investigation was conducted in order to understand properties of grouts and grouted specimens. Three different cement types, i.e., composite ultrafine cement (CUC) that was independently developed, ultrafine cement (UC), and Portland cement (PC) were injected into broken red sandstone specimens on the basis of a self-designed grouting test equipment. After the grouting test, the effects on the mechanical behavior of grouted specimens were studied using an uniaxial compression test, macroscopic failure analysis and mesostructure analysis, as well as a comparison of the mechanical and structural properties of three types of grouted specimens was presented. The test results show that the compressive strength of grouted specimens improved in comparison to the rock residual strength, and the compressive strength of PC, UC and CUC grouted specimens increased by 23.0%, 59.6% and 101.5%, respectively. The failure modes of all grouted specimens were brittle failure, but only the CUC grouted specimen was failed along the new failure surfaces, indicating that CUC grouts can better bond the original cracks. The mesostructure characteristics obtained through the Digital 3D Video Microscope reveal the superior filling effect of the CUC grouts as well as verifying the macroscopic mechanical behavior.

Experimental investigation of the mechanical behaviors of grouted crushed coal rocks under uniaxial compression

Jin, Yuhao,Han, Lijun,Meng, Qingbin,Ma, Dan,Wen, Shengyong,Wang, Shuai Techno-Press 2018 Geomechanics & engineering Vol.16 No.3

A detailed understanding of the mechanical behaviors for crushed coal rocks after grouting is a key for construction in the broken zones of mining engineering. In this research, experiments of grouting into the crushed coal rock using independently developed test equipment for solving the problem of sampling of crushed coal rocks have been carried out. The application of uniaxial compression was used to approximately simulate the ground stress in real engineering. In combination with the analysis of crack evolution and failure modes for the grouted specimens, the influences of different crushed degrees of coal rock (CDCR) and solidified grout strength (SGS) on the mechanical behavior of grouted specimens under uniaxial compression were investigated. The research demonstrated that first, the UCS of grouted specimens decreased with the decrease in the CDCR at constant SGS (except for the SGS of 12.3 MPa). However, the UCS of grouted specimens for constant CDCR increased when the SGS increased; optimum solidification strengths for grouts between 19.3 and 23.0 MPa were obtained. The elastic moduli of the grouted specimens with different CDCR generally increased with increasing SGS, and the peak axial strain showed a slightly nonlinear decrease with increasing SGS. The supporting effect of the skeleton structure produced by the solidified grouts was increasingly obvious with increasing CDCR and SGS. The possible evolution of internal cracks for the grouted specimens was classified into three stages: (1) cracks initiating along the interfaces between the coal blocks and solidified grouts; (2) cracks initiating and propagating in coal blocks; and (3) cracks continually propagating successively in the interfaces, the coal blocks, and the solidified grouts near the coal blocks. Finally, after the propagation and coalescence of internal cracks through the entire specimens, there were two main failure modes for the failed grouted specimens. These modes included the inclined shear failure occurring in the more crushed coal rock and the splitting failure occurring in the less crushed coal rock. Both modes were different from the single failure mode along the fissure for the fractured coal rock after grouting solidification. However, compared to the brittle failure of intact coal rock, grouting into the different crushed degree coal rocks resulted in ductile deformation after the peak strength for the grouted specimens was attained.

Formation Mechanism of Slurry Consolidated Body in Different Grouting Media under Dynamic Water Conditions by the Test-simulation Method

Changyu Xu,Lijun Han 대한토목학회 2023 KSCE JOURNAL OF CIVIL ENGINEERING Vol.27 No.1

This study proposes the Test-simulation Method to investigate the formation mechanism of slurry consolidated body in different grouting media under dynamic water conditions, which utilizes the test system to study the basic laws, and the numerical simulation to reveal the mechanism. Firstly, a test system for grouting under dynamic water conditions was developed, which can be used to grout in both porous media and parallel-fissure media. And the effects of water velocity and grouting rate on the slurry-consolidated-body forms were studied by this test system. Secondly, COMSOL Multiphysics was used to simulate the test process, and shapes of the consolidated body in numerical simulation were analyzed and compared with those in the model test, which proved the feasibility of the numerical method. Finally, the variation law of two-phase flow velocity during the grouting process was further studied by numerical simulation, in order to reveal the formation mechanism of the consolidated body. The results show that the slurry consolidated body presents an approximate ‘Fusiform’ shape in the porous medium, while presents a ‘U-shape’ in the parallel-fissure medium. And the final form of the slurry consolidated body is constructed with the joint action of water velocity and grouting rate.