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Resonance analysis of cantilever porous graphene platelet reinforced pipe under external load
Qinghua Huang,Xinping Yu,Jun Lv,Jilie Zhou,Marischa Ray Elvenia 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.3
Nowadays, there is a high demand for great structural implementation and multifunctionality with excellent mechanical properties. The porous structures reinforced by graphene platelets (GPLs) having valuable properties, such as heat resistance, lightweight, and excellent energy absorption, have been considerably used in different engineering implementations. However, stiffness of porous structures reduces significantly, due to the internal cavities, by adding GPLs into porous medium, effective mechanical properties of the porous structure considerably enhance. This paper is relating to vibration analysis of fluidconveying cantilever porous graphene platelet reinforced (GPLR) pipe with fractional viscoelastic model resting on foundations. A dynamical model of cantilever porous GPLR pipes conveying fluid and resting on a foundation is proposed, and the vibration, natural frequencies and primary resonant of such a system are explored. The pipe body is considered to be composed of GPLR viscoelastic polymeric pipe with porosity in which Halpin-Tsai scheme in conjunction with the fractional viscoelastic model is used to govern the construction relation of nanocomposite pipe. Three different porosity distributions through the pipe thickness are introduced. The harmonic concentrated force is also applied to the pipe and the excitation frequency is close to the first natural frequency. The governing equation for transverse motions of the pipe is derived by the Hamilton principle and then discretized by the Galerkin procedure. In order to obtain the frequency-response equation, the differential equation is solved with the assumption of small displacement, damping coefficient, and excitation amplitude by the multiple scale method. A parametric sensitivity analysis is carried out to reveal the influence of different parameters, such as nanocomposite pipe properties, fluid velocity and nonlinear viscoelastic foundation coefficients, on the primary resonance and linear natural frequency. Results indicate that the GPLs weight fraction porosity coefficient, fractional derivative order and the retardation time have substantial influences on the dynamic response of the system.
Localization of Subsurface Targets Based on Symmetric Sub-array MIMO Radar
Qinghua Liu,Yuanxin He,Chang Jiang 한국정보처리학회 2020 Journal of information processing systems Vol.16 No.4
For the issue of subsurface target localization by reverse projection, a new approach of target localization with different distances based on symmetric subarray multipleinput multipleoutput (MIMO) radar is proposed in this paper. By utilizing the particularity of structure of the two symmetric subarrays, the received signals arejointly reconstructed to eliminate the distance information from the steering vectors. The distanceindependent direction of arrival (DOA) estimates are acquired, and the localizations of subsurface targets with different distances are realized by reverse projection. According to the localization mechanism and application characteristics of the proposed algorithm, the grid zooming method based on spatial segmentation is used to optimize the locaiton efficiency. Simulation results demonstrate the effectiveness of the proposed localization method and optimization scheme.
Experimental research on load-bearing capacity of cast steel joints for beam-to-column
Qinghua Han,Mingjie Liu,Yan Lu 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.1
The load transfer mechanism and load-bearing capacity of cast steel joints for H-shaped beam to square tube column connection are studied based on the deformation compatibility theory. Then the monotonic tensile experiments are conducted for 12 specimens about the cast steel joints for H-shaped beam to square tube column connection. The findings are that the tensile bearing capacity of the cast steel joints for beam-column connection depends on the ring of cast steel stiffener. The tensile fracture happens at the ring of the cast steel stiffener when the joint fails. The thickness of square tube column has little influence on the bearing capacity of the joint. The square tube column buckles while the joint without concrete filled, but the strength failure happens for the joint with concrete filled column. And the length of welding connection between square tube column and cast steel stiffener has little influence on the load-bearing capacity of the cast steel joint. Finally it is shown that the load-bearing capacity of the joints for H-shaped beam to concrete filled square tube column connection is larger than that of the joints for H-shaped beam to square tube column connection by 10% to 15%.
Qinghua Wang,Wei Wang,Junlin Huang,Hong Yin,Yucan Zhu,Haitao Wang,Minjie Zhou,Binhong He,Zhaohui Hou,Wenyuan Xu 한국탄소학회 2023 Carbon Letters Vol.33 No.1
Transition-metal phosphides (TMPs), a promising anode material for lithium-ion batteries (LIBs), are limited in application because of its serious volume effect in the cycle. In this work, a simple electrospinning strategy was proposed to restrict the grain size of CoP nanocrystals by nano-confined effect of carbon nanofibers with ligands. The addition of ligands not only could realize the uniform dispersion of CoP nanocrystals, but also strengthen the bond between the metals and carbon nanofibers. As a result, the CoP/CNF composite exhibits excellent lithium storage performance, and its reversible specific capacity could reach 1016.4 mAh g? 1 after 200 cycles at a current density of 200 mA g? 1. The research is anticipated to provide a new idea for the preparation of anode materials for lithium ion batteries.
Cyclic Response and Constitutive Model Study of G20Mn5QT Cast Steel
Qinghua Han,Qianwen Huang,Yan Lu 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.4
A series of cyclic loading tests of G20Mn5QT cast steel are carried out at the strain ratio of − 1. The results of tests show that the G20Mn5QT cast steel has the similar tendency in cyclic softening with diff erent constant strain amplitude. A slight strain softening is observed, and then the stress states keep steady during the remaining cycles. A new damage variable is proposed considering the eff ects of strength degeneration within two inner variables which are the maximum equivalent plastic strain and the equivalent plastic strain increment. The damage variable provides better insight into the multiaxial cyclic loading and gives a reasonable prediction of failure under the loading history of constant strain amplitude. The proposed damage variable is further introduced in the cyclic constitutive model by the user subroutine interfaces VUMAT by the software ABAQUS. The relationships between the equivalent plastic strain and the damage variable, Young’s modulus and yield strength are fi nally put forward as it is expedient to get the equivalent plastic strain in the numerical analysis.
Qinghua Hu,Songxiao Li 대한수학회 2017 대한수학회지 Vol.54 No.2
In this paper, we characterize the boundedness, compactness and essential norm of products of differentiation and composition operators from the Bloch space and weighted Dirichlet spaces to analytic Morrey type spaces.
Thermally Healable Polyurethanes Based on Furfural-Derived Monomers via Baylis-Hillman Reaction
Qinghua Huang,Fanghong Yang,Xingxing Cao,Zhongyu Hu,Chuanjie Cheng 한국고분자학회 2019 Macromolecular Research Vol.27 No.9
Two novel acrylate monomers with diol group, 2-hydroxyethyl 2-(furan- 2-yl(hydroxy)methyl)acrylate and methyl 2-(hydroxy(5-(hydroxymethyl)furan-2- yl)methyl)acrylate, were synthesized via Baylis-Hillman reaction in moderate yields. The monomer 2-hydroxyethyl 2-(furan-2-yl(hydroxy)methyl)acrylate was obtained from furfural and 2-hydroxyethyl acrylate (HEA); methyl 2-(hydroxy(5-(hydroxymethyl)furan- 2-yl)methyl)acrylate was prepared from 5-hydroxymethl furfural (HMF) and methyl acrylate. The monomer 2-hydroxyethyl 2-(furan-2-yl(hydroxy)methyl)acrylate reacted with toluene diisocyanate (TDI)-derived or hexamethylene diisocyanate (HDI)-derived diisocyanate oligomers to obtain the corresponding linear polyurethane oligmers PU-1T and PU-1H. Similarly, the diol methyl 2-(hydroxy(5-(hydroxymethyl)furan- 2-yl)methyl)acrylate reacted with TDI- or HDI-derived diisocyanate oligomers to obtain the corresponding linear polyurethane oligmers PU-2T and PU-2H. The numberaverage molecular weights of the linear polyurethane oligomers are approximately 300-350 Da. There are furan groups in the linear polyurethane oligomers PU-1T, PU-1H, PU-2T and PU-2H, which makes them capable of undergoing reversible Diels-Alder reaction with 4,4'- bismaleimidodiphenylmethane (BMI) to form the corresponding crosslinked polyurethanes CPU-1T, CPU-1H, CPU-2T and CPU-2H. Pencil hardness of CPU-1T, CPU-1H, CPU-2T and CPU-2H are 3H, 2H, 2H and HB, respectively. Glass transition temperatures of CPU-1T, CPU- 1H, CPU-2T and CPU-2H are 104.8, 97.6, 5.1 and 1.2 oC, respectively. TGA analysis shows that Td90 values of the CPUs range from 180 to 250 oC. Furthermore, the reversible crosslinked polyurethanes CPU-1T and CPU-1H can be completely self-healed at 90 oC for 3 h, while CPU-2T and CPU-2H can self-heal at 80 oC for 3 h presumably due to their low glass transition temperatures.
( Qinghua Liu ),( Qingping Li ) 한국정보처리학회 2021 Journal of information processing systems Vol.17 No.4
For the mobile edge computing (MEC) system supporting dense network, a joint allocation algorithm of computing and communication resources based on reinforcement learning is proposed. The energy consumption of task execution is defined as the maximum energy consumption of each user's task execution in the system. Considering the constraints of task unloading, power allocation, transmission rate and calculation resource allocation, the problem of joint task unloading and resource allocation is modeled as a problem of maximum task execution energy consumption minimization. As a mixed integer nonlinear programming problem, it is difficult to be directly solve by traditional optimization methods. This paper uses reinforcement learning algorithm to solve this problem. Then, the Markov decision-making process and the theoretical basis of reinforcement learning are introduced to provide a theoretical basis for the algorithm simulation experiment. Based on the algorithm of reinforcement learning and joint allocation of communication resources, the joint optimization of data task unloading and power control strategy is carried out for each terminal device, and the local computing model and task unloading model are built. The simulation results show that the total task computation cost of the proposed algorithm is 5%-10% less than that of the two comparison algorithms under the same task input. At the same time, the total task computation cost of the proposed algorithm is more than 5% less than that of the two new comparison algorithms.
Qinghua Meng,Heyang Zheng,Long-chuan Guo,Chih-Chiang Chen,Zong-Yao Sun,Chuan Hu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.7
The driverless electric vehicle with electric wheels may generate the front wheel shimmy phenomenon more easily. How to mitigate or even eliminate the shimmy phenomenon by active control method is necessary. The current active shimmy control methods do not consider the sensor measurement error. But the sensor measurement error always exists in practice because of sensor design, manufacturing, and external disturbances. Therefore, this paper investigates this issue. Firstly, a one-degree-of-freedom shimmy model of the front wheel is built. The dynamic function of this model is obtained via Lagrange’s theorem. Then, the shimmy control system with unknown sensor measurement error and nonlinearities is presented. A dual domination control method is proposed to construct a linear state observer as well as an output feedback control law for the shimmy control system. By the Lyapunov method, the designed controller is proved to stabilize the shimmy system globally asymptotically. Finally, simulations are carried out to verify the effectiveness of the one-degree-of-freedom shimmy model and proposed dual domination control method.