Effects of viscous damping models on a single-layer latticed dome during earthquakes

Huidong Zhang,Jinpeng Wang,Xiaoshuai Zhang,Guoping Liu 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.4

Rayleigh damping model is recommended in the recently developed Performance-Based Earthquake Engineering (PBEE) methodology, but this methodology does not provide sufficient information due to the complexity of the damping mechanism. Furthermore, each Rayleigh-type damping model may have its individual limitations. In this study, Rayleigh-type damping models that are used widely in engineering practice are discussed. The seismic performance of a large-span single-layer latticed dome subjected to earthquake ground motions is investigated using different Rayleigh damping models. Herein a simulation technique is developed considering low cycle fatigue (LCF) in steel material. In the simulation technique, Ramberg-Osgood steel material model with the low cycle fatigue effect is used to simulate the non-uniformly distributed material damping and low cycle fatigue damage in the structure. Subsequently, the damping forces of the structure generated by different damping models are compared and discussed; the effects of the damping ratio and roof load on the damping forces are evaluated. Finally, the low cycle fatigue damage values in sections of members are given using these damping models. Through a comparative analysis, an appropriate Rayleigh-type damping model used for a large span single-layer latticed dome subjected to earthquake ground motions is determined in terms of the existing damping models.

Dynamics and Control of a Flexible-Link Flexible-Joint Space Robot with Joint Friction

Qi Zhang,Xiaofeng Liu,Guoping Cai 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.2

Multi-DOF flexible space robots play a significant role in the on-orbit service. The flexibility of the robots is mainly caused by the flexible links and some flexible drive elements in joints. The vibration generated by the component flexibility can affect the accuracy of control. In this paper, the dynamics and control issues of flexible-link flexible-joint (FLFJ) space robots considering joint friction are studied. Firstly, the Spong’s model is employed to depict flexible joints, and the Coulomb friction model is adopted to describe joint friction. Then based on the single direction recursive construction method and velocity variation principle, dynamic equations of the system are derived. Secondly, a trajectory of joint motion is given and a trajectory tracking controller with friction compensation is designed with the computed torque method. Finally, several numerical simulations are carried out to verify the accuracy of the dynamic model and illustrate the effect of joint friction and joint flexibility on the dynamic characteristics of space robots. Besides, simulation results suggest that the controller designed in this paper could effectively achieve the trajectory tracking control for the 6-DOF FLFJ space robot with joint friction.

Multi Feature Information Fusion Target Image Recognition Based on Hyper Plane Fusion of Learning Prototype

Zhou Gaiyun,Zhang Guoping,Chang Cunhong,Ma Li 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.12

In view of the greater changes of posture, illumination, expression and scene in reality environment have a strong impact on wild face recognition algorithm to identify performance problem, and puts forward a kind of linear discriminant analysis side information (SILD) algorithm on hyperplane fusion of learning prototype. First of all, using support vector machine (SVM) to weak tag of data-concentrated sample is expressed as the middle-level characteristics of prototype hyperplane, using a learning combination coefficient to select sparse support vector set from untagged conventional data set; then, under the constraints of the combination sparse coefficient of SVM model, by using Fisher linear discriminant criterion to maximize discriminant ability of untagged data set, and using the iterative optimization algorithm to solve the objective function; in the end, using SILD for feature extraction, cosine similarity measure to complete the final face recognition. In two general face data sets of wild face recognition (LFW) and YouTube, it makes comparison of PHL+SILD method and low-level features + SILD method on some characteristics, such as strength, LBP, Gabor feature and Block Gabor feature, average accuracy, area under the curve (AUC) and entire error rate (EER). The validity and reliability of the proposed algorithm is verified by the experiments.

A Novel Design of High-Efficiency Multi-junction Solar Cell with Quantum/Barrier Wells (QBW-SC) Using Drift–Diffusion Mothod

Qian Yece,Shi Guoping,Zhang Yufeng 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.1

To achieve the best results of quantum well systems, a solar cell with the best output results is required. This field of study is important because of the capacity to increase the efficiency of the solar cell, which can absorb most of the solar spectrum, which conventional transparent or crystal solar cells cannot do. In this paper, a novel multi-junction solar cell with 13 layers of barrier wells and 14 layers of quantum wells are included in the middle part of the reference solar cell is designed and simulated. To have the best outputs from the Quantum/Barrier Wells Solar Cell (QBW-SC), the thickness of the window, emitter, and base layers are selected as 550, 50, and 50 nm, respectively. In the best case, the short-circuit current is J SC = 71.8594 mA/cm 2 and the open-circuit voltage is V OC = 0.99 V. The rate of fill factor and effi ciency are FF = 87.3472% and ƞ = 59.9674%, respectively, which seems to be acceptable compared to other cases and can be implemented empirically, and of course, it is predicted that the cost has a lower build than the samples provided. Finally, to prove the superiority and optimization of the proposed solar cell structure, it is compared with other similar structures in recent years.

Self-Healing and Shape Memory Linear Polyurethane Based on Disulfide Linkages with Excellent Mechanical Property

Lei Ling,Jinhui Li,Guoping Zhang,Rong Sun,Ching-Ping Wong 한국고분자학회 2018 Macromolecular Research Vol.26 No.4

Self-healing polymeric materials have attracted extensively interests due to the ability to heal the damage autonomously. The self-healing systems based on dynamic disulfide bonds have been the most promising due to the efficient healing capacity at a mild condition. However, it is still of great challenge for designing the polymer with excellent mechanical and self-healing property by a simple synthetic route. Herein, a novel series of self-healing linear polyurethanes with the disulfide linkage as the grafting point were developed. The synthetic polymers all exhibited excellent mechanical properties (breaking strength and elongation at break were as much as 31.91 MPa and 1156% for PU-A). Meanwhile, the effects of different ratios of soft/hard segments on the mechanical properties and healing efficiencies have been investigated by stress-strain tests. The results showed that with the increase of soft segments contents, the breaking strength and elongation at break of the polymer improved significantly, while the healing efficiency and Young’s modulus showed a declining trend. The self-healing polyurethane can quickly restore its over 90% of mechanical property after healing at moderate temperature for 10 min. The cyclic tensile tests also showed the dissipated efficiencies and self-recovery abilities of the polymers. Finally, the recovery capability tests verified the shape memory effect in the polymers, which can replace an external force to accelerate the healing process.

A hybrid method for dynamic stiffness identification of bearing joint of high speed spindles

Yongsheng Zhao,Bingbing Zhang,Guoping An,Zhifeng Liu,Ligang Cai 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.1

Bearing joint dynamic parameter identification is crucial in modeling the high speed spindles for machining centers used to predict the stability and natural frequencies of high speed spindles. In this paper, a hybrid method is proposed to identify the dynamic stiffness of bearing joint for the high speed spindles. The hybrid method refers to the analytical approach and experimental method. The support stiffness of spindle shaft can be obtained by adopting receptance coupling substructure analysis method, which consists of series connected bearing and joint stiffness. The bearing stiffness is calculated based on the Hertz contact theory. According to the proposed series stiffness equation, the stiffness of bearing joint can be separated from the composite stiffness. Then, one can obtain the bearing joint stiffness fitting formulas and its variation law under different preload. An experimental set-up with variable preload spindle is developed and the experiment is provided for the validation of presented bearing joint stiffness identification method. The results show that the bearing joint significantly cuts down the support stiffness of the spindles, which can seriously affects the dynamic characteristic of the high speed spindles.

Effect of Cr2O3 on the viscosity and structure of slag (or glass) of CaO-MgO-Al2O3-SiO2 system

Wang Yifan,Wang Yici,Zhang Yunhao,Chai Yifan,Zhao Fengguang,Luo Guoping 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7

The glass-ceramics of CaO-MgO-Al2O3-SiO2-Cr2O3 system was prepared by melting method using blast furnace slag, low-carbon ferrochrome alloy slag and quartz sand as raw materials, and the effect of Cr2O3 on the viscosity and structure of slag (or glass) of CaO-MgO-Al2O3-SiO2 (CMAS) system at high temperature was studied. The Urbain viscosity prediction model was established and optimized, and the effect of Cr2O3 on the structure of slag (or glass) was studied by Raman spectroscopy. The results show that when the mass fraction of Cr2O3 is in the range of 0.85–2.05%, the viscosity of slag (or glass) of CMAS system decreases with the increase of Cr2O3 content. The average relative errors between the experimented viscosity value and the calculated viscosity value obtained by using the optimized Urbain model are less than 20%, which is effective and universal for the viscosity prediction of slag (or glass) of CaO-MgO-Al2O3-SiO2-Cr2O3 system. With the increase of Cr2O3 content, the complex silicon oxygen tetrahedrons (Q3) disintegrate into a larger number of simple silicon oxygen tetrahedrons (Q0, Q1, Q2), resulting in the sparse structure of the melt network and a decrease in macroscopic viscosity.

Torrential Rainfall Responses to Radiation and Ice Clouds over Jiang-Huai Valley, China in July 2007

Fengwen Xu,Xiaofeng Xu,Xiaopeng Cui,Guoping Zhang 한국기상학회 2013 Asia-Pacific Journal of Atmospheric Sciences Vol.49 No.4

The effects of radiation and ice clouds on a torrential rainfall event of Jiang-Huai Valley over China are investigated through a series of two-dimensional sensitivity cloud-resolving model experiments. The model is integrated with an imposed large-scale vertical velocity and zonal wind constructed from the National Centers for Environmental Prediction (NCEP)/Global Data Assimilation System (GDAS) from 2 to 9 July 2007, while the control experiment is compared with two sensitivity experiments that exclude radiation and ice clouds, respectively. The exclusion of ice clouds decreases model domain mean surface rain rate through the weakened mean net condensation and the mean hydrometeor change from loss to gain during the life span of the rainfall event. The sensitivity of the mean rain rate to radiation occurs only in the later period of the rainfall event and is less than that to ice clouds. The reduction in the mean rain rate caused by the elimination of radiation is associated with the decreases in the mean net condensation and latent heat, which corresponds to the strengthened mean local atmospheric cooling.

Research Progress of the Structure Vibration-Attitude Coordinated Control of Spacecraft

Yang, Jingyu,Qu, Shiying,Lin, Jiahui,Liu, Zhiqi,Cui, Xuanming,Wang, Chu,Zhang, Dujiang,gu, Mingcheng,Sun, Zhongrui,Yang, Kang,Zhou, Lanwei,Chen, Guoping The Korean Society for Aeronautical and Space Scie 2015 International Journal of Aeronautical and Space Sc Vol.16 No.4

This paper gives an overview of research on the field of structure vibration-attitude coordinated control of spacecraft. First of all, the importance of the technology has been given an introduction, and then later the research progress of space structure dynamics modeling, research progress of structure vibration-attitude coordinated control of flexible spacecraft have been discussed respectively. Finally, future research on application of structure vibration-attitude coordinated control of spacecraft has been recommended.

Discrimination of Camellia seed oils extracted by supercritical CO2 using electronic tongue technology

Di Duan,Yong Huang,Ying Zou,Bingju He,Ruihui Tang,Liuxia Yang,Zecao Zhang,Shucai Su,Guoping Wang,Deyi Zhang,Chunhui Zhou,Jing Li,Maocheng Deng 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.10

Analytical method which combines electronictongue technique and chemometrics analysis is developedto discriminate oil types and predict oil quality. All thestudied Camellia oil samples from pressing, n-hexaneextraction and supercritical CO2 extraction (SCCE), weresuccessfully identified by principal component analysis(PCA) and hierarchical cluster analysis (HCA). Furthermore,multi factor linear regression model (MLRM) wasestablished to predict oil quality, which are indicated byacid value (AV) and peroxide value (POV). The practicalpotential of e-tongue for the discrimination and assessmentof Camellia oils has shown promising application in thecharacterization of Camellia oils in the oil qualityevaluation.