Levy-type solution for analysis of a magneto-electro-elastic panel

Jia He,Xuejiao Zhang,Hong Gong,H. Elhosiny Ali,Elimam Ali 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.6

This paper studies electro-magneto-mechanical bending studying of the cylindrical panels based on shear deformation theory. The cylindrical panel is constrained with two simply-supported edges at longitudinal direction and two clamped boundary conditions at circumferential direction. The governing equations are derived based on the principle of virtual work in cylindrical coordinate system. Levy-type solution of the governing equations is derived to reduce two dimensional PDEs to a 2D ODEs. The reduced ordinary differential equation is solved using the Eigen-value Eigen-vector method for the clamped-clamped boundary condition. The electro-magneto-mechanical bending results are obtained to show that every displacement, rotation and electromagnetic potentials how change with changes of initial electromagnetic potentials and mechanical loads along longitudinal and circumferential directions.

An improved extended Kalman filter for parameters and loads identification without collocated measurements

Jia He,Mengchen Qi,Zhuohui Tong,Xugang Hua,Zheng Qing Chen 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.31 No.2

As well-known, the extended Kalman filter (EKF) is a powerful tool for parameter identification with limited measurements. However, traditional EKF is not applicable when the external excitation is unknown. By using least-squares estimation (LSE) for force identification, an EKF with unknown input (EKF-UI) approach was recently proposed by the authors. In this approach, to ensure the influence matrix be of full column rank, the sensors have to be deployed at all the degrees-offreedom (DOFs) corresponding to the unknown excitation, saying collocated measurements are required. However, it is not easy to guarantee that the sensors can be installed at all these locations. To circumvent this limitation, based on the idea of first-orderholder discretization (FOHD), an improved EKF with unknown input (IEKF-UI) approach is proposed in this study for the simultaneous identification of structural parameters and unknown excitation. By using projection matrix, an improved observation equation is obtained. Few displacement measurements are fused into the observation equation to avoid the so-called low-frequency drift. To avoid the ill-conditioning problem for force identification without collocated measurements, the idea of FOHD is employed. The recursive solution of the structural states and unknown loads is then analytically derived. The effectiveness of the proposed approach is validated via several numerical examples. Results show that the proposed approach is capable of satisfactorily identifying the parameters of linear and nonlinear structures and the unknown excitation applied to them.

Involvement of Phosphatidylinositol 3-Kinase/Akt Signaling Pathway in β1 Integrin-Mediated Internalization of Staphylococcus aureus by Alveolar Epithelial Cells

Jia-He Wang,Ke Zhang,Nan Wang,Xiao-Min Qiu,Yi-Bing Wang,Ping He 한국미생물학회 2013 The journal of microbiology Vol.51 No.5

The invasion of Staphylococcus aureus into alveolar epithelial cells is regarded as the key step for S. aureus lung infection. However, the mechanism of internalization of S. aureus by alveolar epithelial cells is not clear, and was the aim of this investigation Human lung adenocarcinomic epithelial cells and A549 cells were used. Human β1 integrin and rat β1 integrin were detected by real-time reverse transcription (RT)-PCR. The expressions of β1 integrin, Akt and p-Akt were detected by Western blot analysis. To further investigate the role of β1 integrin in S. aureus internalization by alveolar epithelial cells, we next performed siRNA-mediated knockdown of β1 integrin expression. In this study, we found that S. aureus invades human alveolar epithelial cells and rat primary alveolar epithelial cells. The β1 integrin ligand competitive inhibitor, GRGDS-peptide, blocked the internalization of S. aureus by A549 cells. Knockdown of β1integrin also inhibited the internalization of S. aureus. In addition, the PI3K/Akt signaling pathway in alveolar epithelial cells was activated by the infection with S. aureus. Furthermore, Akt phosphorylation was abolished by transient transfection with β1 integrin siRNA in A549 cells challenged with S. aureus. Our results suggest that the phosphatidylinositol 3-kinase/Akt signaling pathway plays an important role in β1 integrin-mediated internalization of S. aureus by alveolar epithelial cells.

ADAPTABILITY OF LASER TEXTURED LINER TO THE EFFECTS OF METHANOL DILUTING OIL ON TRIBOLOGICAL PROPERTIES

Jia He Kun,Xu Bo,Yin Bifeng,Jiang Yuhao,Hu Nanrong 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.2

With the increase of methanol diluting lubrication oil, the dynamic viscosity of the mixture presents a downward trend, the total acid number grows while the total base number declines, and the corrosion degree of copper strip upgrades, which indicates that methanol dilution has negative effects on lubrication and anti-corrosion performance of oil. According to ball-on-plate friction test results, the friction coefficient and surface wear of this pair increase in turn with the rising methanol dilution rate, which tends to deteriorate the tribological performance of key friction pairs in methanol engine. After laser surface texturing cylinder liner, the friction coefficient of ring/liner pair is reduced, and the anti-friction effect is enhanced with the rising methanol dilution rate, because the oil storage capacity of textured micro-dimples on liner surface can improve the lubrication of ring/liner pair and reduce asperity contact. Moreover, the micro-dimples can store debris generated in the reciprocating friction process of this pair, so as to alleviate surface wear caused by abrasive wear, and improve the wear resistance of cylinder liner. Therefore, laser texturing cylinder liner can compensate the deterioration of friction and wear performance of ring/liner pair caused by methanol diluting oil with good lubrication adaptability.

Distinct Electronic Structure for the Extreme Magnetoresistance in YSb

He, Junfeng,Zhang, Chaofan,Ghimire, Nirmal J.,Liang, Tian,Jia, Chunjing,Jiang, Juan,Tang, Shujie,Chen, Sudi,He, Yu,Mo, S.-K.,Hwang, C. C.,Hashimoto, M.,Lu, D. H.,Moritz, B.,Devereaux, T. P.,Chen, Y. L American Physical Society 2016 Physical Review Letters Vol.117 No.26

Optimum control system for earthquake-excited building structures with minimal number of actuators and sensors

Jia He,You-Lin Xu,Chao-Dong Zhang,Xiao-Hua Zhang 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.6

For vibration control of civil structures, especially large civil structures, one of the important issues is how to place a minimal number of actuators and sensors at their respective optimal locations to achieve the predetermined control performance. In this paper, a methodology is presented for the determination of the minimal number and optimal location of actuators and sensors for vibration control of building structures under earthquake excitation. In the proposed methodology, the number and location of the actuators are first determined in terms of the sequence of performance index increments and the predetermined control performance. A multi-scale response reconstruction method is then extended to the controlled building structure for the determination of the minimal number and optimal placement of sensors with the objective that the reconstructed structural responses can be used as feedbacks for the vibration control while the predetermined control performance can be maintained. The feasibility and accuracy of the proposed methodology are finally investigated numerically through a 20-story shear building structure under the El-Centro ground excitation and the Kobe ground excitation. The numerical results show that with the limited number of sensors and actuators at their optimal locations, the predetermined control performance of the building structure can be achieved.

Research on the Impact of China’s High-Speed Railway Construction on Regional Economy-Take Xibao High-Speed R ail as an Example-

He, Jia(하가),Chen, Lu(션루),Zhang, Meng-Ze(장몽택),Bae, Ki-Hyung(배기형) 한국물류학회 2019 물류학회지 Vol.29 No.5

서보(西寶) 고속철도는 산시성(陕西省) 서안(西安)에서 보계(寶雞)까지 산시성 관중(關中) 지역에 있다. 서보 고속철도는 국가 중점 철도 인프라 건설 프로젝트이고 서안, 함양(鹹陽), 보계, 양릉시범구(楊淩示範區)를 지나며 서안북(西安北), 함양진도(鹹陽秦都), 양릉남(楊淩南), 기산(岐山)과 보계남(寶雞南) 등 5개 역이 있다. 본문은 고속철도는 지역 경제 발전에 미치는 영향에 관한 이론과 문헌을 고찰하여 고속철도 발전이 지역 경제 발전에 관련 메커니즘을 요약하였다. 이를 바탕으로 본문은 서보 고속철도를 대상으로 DID모델을 사용하여 서보고속 철도가 연선 지역의 경제 발전에 미치는 영향을 실증 분석을 실행하였다. 연구 결과에 따르면 서보 고속철도는 연선의 경제 성장을 촉진하는 데 중요한 역할을 한다. 따라서 고속철도는 철도 연선 지역 경제 발전을 촉진하는 데 중요한 역할을 한다는 결론을 내릴 수 있고 고속철도의 건선은 연선 지역의 경제 발전에 큰 도움이 된다는 것을 알 수 있다. 또한 본문은 산시성 고속철도 건설에 대한 정책적 조언과 고속철도 건설을 가속화하기 위한 제안도 제시하였다. Xibao High-speed Railway is located in Guanzhong area of S haanxi Province, from Xi’an City in Shaanxi Province to Baoji City in Shaanxi Province in the west. It passes through Xi’an, Xianyang, Baoji and Yangling Demonstration Zones. There are five stations in the whole line, including Xi’an North Station and Xianyang. Qindu Station, Yangling South Station, Qishan Station, Baoji South Station, and Xibao High-speed Railway are key national railway infrastructure construction projects. The paper summarizes the relevant theories and literatures of the impact of high-speed rail on regional economic development, and summarizes the relevant mechanisms of high-speed rail development on regional economic development. By using Xibao high-speed rail as an example, the DID model is used to study the area along the Xibao high-speed railway. The impact of economic development has found that Xibao High-speed Railway has a significant role in promoting economic growth along the route. Therefore, it is concluded that high-speed rail has an important role in promoting and promoting the economic development along the line. The construction of high-speed rail will be of great help to the regional economic development along the line. Finally, relevant policy recommendations were put forward for the construction of high-speed railways in Shaanxi Province, and relevant suggestions for accelerating the construction of high-speed railways in Shaanxi Province were put forward.

An improved Kalman filter for joint estimation of structural states and unknown loadings

Jia He,Xiaoxiong Zhang,Naxin Dai 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.24 No.2

The classical Kalman filter (KF) provides a practical and efficient way for state estimation. It is, however, not applicable when the external excitations applied to the structures are unknown. Moreover, it is known the classical KF is only suitable for linear systems and can’t handle the nonlinear cases. The aim of this paper is to extend the classical KF approach to circumvent the aforementioned limitations for the joint estimation of structural states and the unknown inputs. On the basis of the scheme of the classical KF, analytical recursive solution of an improved KF approach is derived and presented. A revised form of observation equation is obtained basing on a projection matrix. The structural states and the unknown inputs are then simultaneously estimated with limited measurements in linear or nonlinear systems. The efficiency and accuracy of the proposed approach is verified via a five-story shear building, a simply supported beam, and three sorts of nonlinear hysteretic structures. The shaking table tests of a five-story building structure are also employed for the validation of the robustness of the proposed approach. Numerical and experimental results show that the proposed approach can not only satisfactorily estimate structural states, but also identify unknown loadings with acceptable accuracy for both linear and nonlinear systems.

The effect of cobalt ions doping in ZnCr2O4 spinel oxide for the catalytic activity of methane combustion

He Jia,Shao Xiaoqiang,Su Qin,Zhao Donglin,Feng Shaojie,오원춘 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.1

A series of novel cobalt ion-doped ZnCr2−xCoxO4 (x = 0, 0.1, 0.15, 0.2) spinel oxides were synthesized with the hydrothermal method. X-ray diffraction, scanning electron microscope, specific surface area, Raman spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption of oxygen, and other analytical techniques were used to characterize the structure, morphology, and catalytic performance of each sample. Experiment results showed that the doping of cobalt ion significantly promoted the phase crystallization of spinel oxide. Cobalt ion-doped ZnCr2−xCoxO4 (x = 0.1, 0.15, 0.2) nanoparticles with high specific surface area were synthesized at 773 K, with ZnCr2O4 forming a spinel phase at 1173 K. Catalytic experiments revealed that the catalytic activity of ZnCr2−xCoxO4 was effectively improved. Cobalt ion-doped ZnCr1.85Co0.15O4 catalyst catalyzed methane combustion reaction temperature at T90% (the temperature where 90% of methane was converted) of about 573 K, while the undoped ZnCr2O4 sample had the highest catalytic performance at T90% of about 773 K. The order of catalytic activity was: ZnCr1.85Co0.15O4 > ZnCr1.9Co0.1O4 > ZnCr1.8Co0.2O4 > ZnCr2O4. Results of catalytic experiments showed that the surface area of the catalyst increased after partial replacement of chromium ions by cobalt ions and that the increase in surface area of the catalyst provided more active sites, thus improving the reaction activity.

Wettability contrast on the surface of CuO nanostructures for highly efficient fog harvesting

He Wen-xin,Jin Lian-lian,Ma Xiu-jia,Li Xiao,Li Jia,Wang Xue-wei 한국물리학회 2023 Current Applied Physics Vol.53 No.-

Fog collection can provide a sustainable and efficient method for solving the shortage of water resources. In this article, CuO nanostructures were designed and synthesized on the Cu mesh by a one-step oxidation method and used to collect water from fog. Their morphology and surface wettability are characterized through scanning electron microscopy and dynamic contact angle measuring device, while the process of fog collection is investigated by a high-speed camera. The fog collection efficiency depends on the microstructure of the sample surface, which could be well controlled by adjusting the reaction temperature. Compared with CuO nanoneedles and CuO nanowire clusters, CuO nanosheets promote the rapid falling of liquid droplets, improving the fog harvesting efficiency, which can achieve 3168 mg/cm2 within 120 s. CuO nanosheets have ultra-low adhesion due to high roughness and high air restraint ability, accelerating the transport of water droplets and reducing the re-evaporation of water droplets.