Rapid Stress Analytical Solutions of Steel Strips Subjected to Non-uniform Tensile Loads Based on New Symplectic Method

Haijun Yu,Anrui He,Wenquan Sun,Chihuan Yao,Chao Liu 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5

This paper deals with the stress distribution problem of steel strips subjected to non-uniform tensile loads at both ends, which induce the transverse in-plane compressive stress and is important for researching the transverse buckling of the steel strip. For stress distribution problem, the traditional fi nite element method (FEM) has acceptable accuracy while it takes too long computing time to be applied to on-site production and the semi-inverse analytical method needs to preset the form of stress solution and gets the solution with a certain error. Thence, a rapid symplectic analytical method for solving stress distribution problem of steel strips is presented, which is based on the Hamiltonian system unlike other traditional method based on the Lagrangian system. Furthermore, the rational and rigorous derivation without any forecast about the form of solution makes the stress result have high precision with short computing time. Finally, the symplectic method is demonstrated be more effi cient and suitable in the on-line calculation by comparing with FEM.

BER Analysis of Coherent Free Space Optical Communication Systems with Holographic Modal Wavefront Sensor

Liu, Wei,Yao, Kainan,Huang, Danian,Cao, Jingtai,Wang, Liang,Gu, Haijun Optical Society of Korea 2017 Current Optics and Photonics Vol.1 No.1

Degradation of bit-error-rate (BER), caused by atmospheric turbulence, seriously hinders the performance of coherent Free Space Optical (FSO) communication systems. An adaptive optics system proves to be effective in suppressing the atmospheric turbulence. The holographic modal wavefront sensor (HMWFS) proposed in our previous work, noted for its fast detecting rates and insensitivity to beam scintillation, is applied to the coherent FSO communication systems. In this paper, based on our previous work, we first introduce the principle of the HMWFS in brief and give the BER of the coherent FSO with homodyne detection in theory, and then analyze the improvement of BER for a coherent FSO system based on our previous simulation works. The results show that the wavefront sensor we propose is better for weak atmospheric turbulence. The most obvious advantages of HMWFS are fast detecting rates and insensitivity to beam scintillation.

Algorithms of Brainstem Auditory Evoked Potential Extraction

Haijun Lin,Xinlei Wang,Jia Yu,Bo Liu 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.10

To extract the brainstem auditory evoked potentials and remove the spontaneous electroencephalograph and other background noises, the paper proposed a new method of wavelet information entropy theory de-noising based on wavelet de-noising. In the method, the threshold function is improved by introducing the weighting factor and determine the weighting factor according to the wavelet information entropy to obtain a better de-noising effect. The simulation experiment shows, compared to the traditional wavelet de-noising method, the new method can preserve the details of the signal better and make the signal waveform smoother. At the same time, the new method can suppress the pulse signal, which make the system has a better de-noising performance and achieve higher quality extraction brainstem auditory evoked potentials.

Low-Carbon Economic Dispatch of an Integrated Energy System Based on Carbon Emission Flow Theory

Liu Zheyuan,Xing Haijun,Luo Yangfan,Ye Yujing,Shi Yusong 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3

To address the problem of low carbon economic dispatch of integrated energy systems, carbon emission flow theory is introduced into the optimal dispatch of integrated energy systems. Firstly, the carbon emission flow model is used to calculate the carbon emissions of each load in the framework of the electricity-gas integrated energy system. Secondly, the Shapley value method is introduced into the integrated energy system carbon trading model to analyze its incentive effect on emission reduction. Finally, a bi-level dispatching model of the integrated energy system is established, with the upper level being the grid and gas network dispatching model with the minimum operating cost as the objective function, and the lower level being the energy hub dispatching model with the minimum operating cost as the objective function. Low carbon economic dispatching is carried out with the objective function of minimizing operating costs. The model is verified through arithmetic examples to have the effect of improving energy utilization, reducing operating costs, and reducing carbon emissions, and can achieve low carbon economic operation.

The Research on Fusion and Diagnosis Method of Multi Soft Fault of Nonlinear Analog Circuit

Haijun Lin,Jiren Han,Xuhui Zhang,Jingbo Xu,Yunfeng Liu 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.11

For the single source characteristics of the insufficient problem of nonlinear analog circuit soft fault diagnosis, we propose a new method that is based on dual Wiener core for fault diagnosis of intelligent information optimization fusion[1,2,3,4,5], firstly, the incentive is Gauss white noise, after sampling we obtain the Wiener core of circuit and power which is used from the discrete Wiener core, then use the improved genetic algorithm, make the feature selection and fusion combination as an optimization problem, propose intelligent optimization fusion extraction based on the improved genetic algorithm, the circuit set total Euclidean distance as the objective function optimizes, the different information in feature layer can be organic integration, then use the BP neural network for intelligent diagnosis. Experiments show that the method can effectively improve the accuracy of the diagnosis of nonlinear multiple soft faults.

BER Analysis of Coherent Free Space Optical Communication Systems with Holographic Modal Wavefront Sensor

Wei Liu,Kainan Yao,Danian Huang,Jingtai Cao,Liang Wang,Haijun Gu 한국광학회 2017 Current Optics and Photonics Vol.1 No.1

Degradation of bit-error-rate (BER), caused by atmospheric turbulence, seriously hinders the performanceof coherent Free Space Optical (FSO) communication systems. An adaptive optics system proves to beeffective in suppressing the atmospheric turbulence. The holographic modal wavefront sensor (HMWFS)proposed in our previous work, noted for its fast detecting rates and insensitivity to beam scintillation,is applied to the coherent FSO communication systems. In this paper, based on our previous work, wefirst introduce the principle of the HMWFS in brief and give the BER of the coherent FSO with homodynedetection in theory, and then analyze the improvement of BER for a coherent FSO system based on ourprevious simulation works. The results show that the wavefront sensor we propose is better for weakatmospheric turbulence. The most obvious advantages of HMWFS are fast detecting rates and insensitivityto beam scintillation.

Experimental Study on the Environmental Effects and Mechanical Characteristics of Solidified Cr(VI)-Contaminated Soil Based on Slag and Desulfurization Gypsum

Mengyi Liu,Haijun Lu,Fuwu Luo,Meng Zang,Jing Zhang 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1

This study proposed a new curing agent consisting of slag and desulfurization gypsum industrialwaste to solidify Cr(VI)-contaminated soils and prevent its migration and bioaccumulation in the ecosphere. The curing agent dosage of 10 – 30% resulted in a Cr(VI) toxic leaching concentration, compressive strength, and hydraulic conductivity range of 0.118 – 5.824 mg/L, 2.70 – 10.22 MPa, and 1.70 × 109–1.37 × 106 cm/s, respectively. Following four dry and wet cycles, the dosage of the curing agent was found to be 20 – 30% to achieve minimum environmental safety requirements. Cr(VI) in the cured specimens mainly existed as CrO42, or acid salt, in which a portion was changed to Cr(III) during precipitation or directly was encased in the silica-alumina mesh structure. The adsorption capacity of hexavalent chrome on the outer of the hydration product groups was insignificant owing to the electronegativity. Hence, the Cr(VI) was solidified by hydrides such as C-S(A)-H and calcium alumina inclusions. Calcite, quartz, and several zeolite-like substances were also found to be colloidal in the pores to block Cr(VI).

Macro-Micro Mechanical Behavior of Crushable Granular Materials under Generalized Stress Conditions

Yiming Liu,Chenming Xu,Guofang Xu,Haijun Mao,Zunqun Xiao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

This paper investigated the joint influence of particle crushing and intermediate principal stress coefficient on the macro and micro performances of granular assembles by using 3D discrete element method. The soil particle was modeled by crushable agglomerate. Numerical true triaxial tests with crushable agglomerates were performed. The mechanical behaviors of specimens with unbreakable agglomerates were also tested in this study. The results demonstrated that grain breakage can significantly affect the behaviors of granular soils in both macro and micro scales. Moreover, the present paper also showed that particle breakage did not influence the unique relationship between the intermediate principal stress coefficient band the deviatoric fabric of strong contacts. This can provide a good basis for developing micro-parameter-based constitutive model considering particle breakage for granular soils.

Efficiency Analysis of Homodyne Detection for a Coherent Lidar with Adaptive Optics

Wei Liu,Liang Wang,Kainan Yao,Jingtai Cao,Danian Huang,Haijun Gu 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.12

For a coherent lidar, the efficiency of homodyne detection is a significant factor. Adaptive optics (AO) is an effective way to correct the turbulence-induced wavefront distortions. Based on our previous works, an expression for the homodyne detection efficiency is given. The results of the numerical simulation show that the atmospheric coherent length has an influence on the homodyne detection efficiency for a fixed atmospheric Greenwood frequency and a closed-loop control bandwidth. In addition, an experimental AO system is employed to verify the effect of the AO on the coherent lidar. The results show that the homodyne detection efficiency is obviously improved after aberrations are corrected. The conclusion of this paper provides a reference for designing an AO system for a coherent lidar.

Temporal Information Services in Large-Scale Vehicular Networks Through Evolutionary Multi-Objective Optimization

Dai, Penglin,Liu, Kai,Feng, Liang,Zhang, Haijun,Lee, Victor Chung Sing,Son, Sang Hyuk,Wu, Xiao IEEE 2019 IEEE transactions on intelligent transportation sy Vol.20 No.1

<P>Temporal information services are critical in implementing emerging intelligent transportation systems. Nevertheless, it is challenging to realize timely temporal data update and dissemination due to an intermittent wireless connection and a limited communication bandwidth in dynamic vehicular networks. Some previous studies have considered the temporal data dissemination in vehicular networks, but they are limited to the service region, which is inside the coverage of roadside units. To enhance system scalability, it is imperative to exploit the synergic effect of vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communications for providing efficient temporal information services in such an environment. With the above motivations, we propose a novel system architecture to enable efficient data scheduling in hybrid V2I/V2V communications by having the global knowledge of network resources of the system. On this basis, we formulate a temporal data upload and dissemination (<I>TDUD</I>) problem, aiming at optimizing two conflict objectives simultaneously, which are enhancing the data quality and improving the delivery ratio. Furthermore, we propose an evolutionary multi-objective algorithm called <I>MO-TDUD</I>, which consists of a decomposition scheme for handling multiple objectives, a scalable chromosome representation for <I>TDUD</I> solution encoding, and an evolutionary operator designed for <I>TDUD</I> solution reproduction. The proposed <I>MO-TDUD</I> can be adaptive to different requirements on data quality and delivery ratio by selecting the best solution from the derived Pareto solutions. Last but not least, we build the simulation model and implement <I>MO-TDUD</I> for performance evaluation. The comprehensive simulation results demonstrate the superiority of the proposed solution.</P>