Analysis and active control for wind induced vibration of beam with ACLD patch

Jinqiang Li,Yoshihiro Narita 한국풍공학회 2013 한국풍공학회지 Vol.17 No.4

The structural vibration suppression with active constrained layer damping (ACLD) was widely studied recently. However, the literature seldom concerned with the vibration control on flow-induced vibration using active constrained layer. In this paper the wind induced vibration of cantilevered beam is analyzed and suppressed by using random theory together with a velocity feedback control strategy. The piezoelectric material and frequency dependent viscoelastic layer are used to achieve effective active damping in the vibration control. The transverse displacement and velocity in time and frequency domains, as well as the power spectral density and the mean-square value of the transverse displacement and velocity, are formulated under wind pressure at variable control gain. It is observed from the numerical results that the wind induced vibration can be significantly suppressed by using a small outside active voltage on the constrained layer.

Development countermeasures of China's renewable energy industry under the influence of financial crisis

Jinqiang Wang,Weibing Cao 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10

The vigorous development and use of renewable energy is an important strategic choice to optimize the struction of energy resources, safeguard the security of energy resources, alleviate environment pollution and balance the development of energy, ecnomoy and environment. Based on the analysis of positive and negative impacts of financial crisis on China"s renewable energy industry. some deveolpment countermeasures of this industry under the influence of financial crisis are proposed.

Dynamic Hedging under Liquidity Risk

Jinqiang Yang,Zhaojun Yang 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10

This paper develops a framework for analyzing dynamic hedging strategies under liquidity risk. The liquidity risk is modeled in discrete time, which says the more you trade the more unfavorable to you the price will get and thus, you must pay more for same amount of assets or get less cash after selling ans asset. The portfolio dynamics under liquidity risk is established provided that portfolio is affine and self-financing. Following that, we present an affine hedging algorithm for computing moments of hedge error. Finally, numerical examples are shown in order to explain the quantitative relations among hedge error, liquidity costs, liquidity level and trading frequency.

Analytical modeling of in-process temperature in powder feed metal additive manufacturing considering heat transfer boundary condition

Jinqiang Ning,Daniel E. Sievers,Hamid Garmestani,Steven Y. Liang 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.3

This paper presents a physics-based predictive model to estimate the in-process temperature in powder feed metal additive manufacturing (PFAM) based on the absolute coordinate with a stationary origin. Quasi-analytical solutions are developed without resorting to FEM or any iteration-based simulations. Heat transfer boundary condition, laser power absorption, scanning strategy, and latent heat are considered in the prediction of time-dependent thermal profi les. The temperature rise due to a moving laser heat source is predicted using a moving point heat source solution. The temperature drop due to convection and radiation at the part boundary is predicted by a heat sink solution, which is derived by modifying the heat source solution with an equivalent power for heat loss and zero velocity. The fi nal temperature solution is constructed from the superposition of the heat source solution and the heat sink solution. Temperature profi les are predicted in multiple layers using the presented model in PFAM of Ti-6Al-4 V for a thin wall structure. Molten pool evolution is investigated with respect to laser travel distance from its starting point. The stabilized molten pool dimensions in multiple layers are obtained from predicted temperatures and agreed well with experimental measurements in the literature. In addition, the increasing molten pool dimensions were observed from predictions with increasing wall thickness, which confi rms the fi nding reported in the literature. With benefi ts of high computational effi ciency of the developed solution, consideration of heat transfer boundary conditions, and absolute coordinate, the presented model can be used for temperature analysis for a dimensional part in real applications.

On the fuzzy-adaptive command filtered backstepping control of an underactuated autonomous underwater vehicle in the three-dimensional space

JinQiang Wang,Cong Wang,Yingjie Wei,ChengJu Zhang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6

This paper studies the three-dimensional path following control problem for an underactuated autonomous underwater vehicle in the presence of parameter uncertainties and external disturbances. Firstly, an appropriate model for the error dynamics was established to solve the path following problem in a moving Serret-Frenet frame. Secondly, an adaptive robust control scheme is proposed through fuzzy logic theory, command filtered backstepping method and an adaptation mechanism. Finally, a suitable Lyapunov candidate function is utilized to verify the stability of the overall control system and demonstrate uniform ultimate boundedness of path following errors. Following novelties are highlighted in this study: (i) The fuzzy method is adopted to solve the problems of model uncertainties, which makes the controller more practical; (ii) to calculate the virtual control derivative, a second-order filter is designed. This reduces the computational effort of the standard backstepping technique. Moreover, the effect of high frequency measurement noise is considerably attenuated via an appropriate filter to attain a more robust control system. (iii) To attain a desired approximation accuracy between the virtual control and the filtered signals, a compensation loop containing the filtered error is established. (iv) An anti-windup design is proposed to solve the problem of integral saturation in control input signals. Finally, comparative simulations are performed to ensure that the presented control scheme has excellent following accuracy and good robustness under multiple uncertainties and external disturbances.

Analysis and active control for wind induced vibration of beam with ACLD patch

Li, Jinqiang,Narita, Yoshihiro Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.4

The structural vibration suppression with active constrained layer damping (ACLD) was widely studied recently. However, the literature seldom concerned with the vibration control on flow-induced vibration using active constrained layer. In this paper the wind induced vibration of cantilevered beam is analyzed and suppressed by using random theory together with a velocity feedback control strategy. The piezoelectric material and frequency dependent viscoelastic layer are used to achieve effective active damping in the vibration control. The transverse displacement and velocity in time and frequency domains, as well as the power spectral density and the mean-square value of the transverse displacement and velocity, are formulated under wind pressure at variable control gain. It is observed from the numerical results that the wind induced vibration can be significantly suppressed by using a small outside active voltage on the constrained layer.

Real option consumption-utility based indifference pricing under stochastic volatility

Feng Shi,Jinqiang Yang,Kui Ma 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10

This paper deals with the consumption-utility based indifference pricing problem of real option under stochastic volatility by analyzing a mixed optimal control and optimal stopping problem under an incomplete market. Implied option value is given by the solution to a two dimensional free-boundary PDE and the numerical results are obtained by the finite difference method. The numerical analysis illustrates that stochastic volatility will increase the implied option value and encourage the agent exericse the option later. Additionally, the stochastic volatility results in more consumption and decreases the precautionary savings motive of the agent. And an increase in the risk aversion attituede raises those effects.

In-Situ Distortion Prediction in Metal Additive Manufacturing Considering Boundary Conditions

Wenjia Wang,Jinqiang Ning,Steven Y. Liang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.5

Undesired distortion often occurs in metal additive manufacturing due to the high temperature gradient resulting from repeated thermal cycles. A good understanding and fast predictions of in-situ distortion are essential to achieve high dimensional accuracy and prevent delamination or failure of build parts. Experimental investigations and numerical methods have been employed to study the in-situ distortion. However, the complex measurement systems and high computational cost limit their applications. An analytical modeling method with closed-form solutions is proposed in this paper to predict the in-situ distortion of laser cladding process without using iteration-based numerical calculations. The effects of build edges and geometry are considered, which include thermal convection and radiation at boundaries. Heat input and heat sink solutions modified from the point moving heat source model are added together to predict the temperature profile of the build and substrate. The die-substrate assembly model is used to calculate the deflection during the manufacturing process. Alloy 625 is selected to test the predictive accuracy and computational efficiency of the presented analytical model. The predicted results are close to the experimental data of in-situ distortion in literature. The computational time is less than 30 s. The good predictive accuracy and low computational cost make the presented method a promising approach to study the full-field temperature and distortion of a geometrically complex part.

Analytical modeling and sensitivity analysis of the temperature distribution in the planar scanning induction heating based on 2D moving heat source

Feng Li,Jinqiang Ning,Tao Wang,Steven Y Liang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.10

This paper presents an analytical modeling method of the temperature evolution in the planar scanning induction heating, which can be applied into various heat treatment processes. Due to the uneven distribution and hard control of the electromagnetic fields in the planar induction coils, it is difficult to achieve the precisely prediction and control of the temperature evolution. In view of the low computational efficiency and the complexity in the establishment of the general finite element numerical simulation models, in this work, analytical models of this planar scanning induction heating enhanced by the magnetic flux concentrator are established by using the moving points and line heat source. The magnetic field and the eddy power density in the workpiece generated by the induction coils are calculated by Maxwell equations and then can be applied into the analytical model of the temperature evolution using the moving points and line heat source. Several sets of the corresponding finite element simulation tests and experimental tests are conducted to validate the analytical calculation results. In addition, sensitivity analysis of the main factors influencing the temperature evolution is conducted. By comparison, it is investigated that the final temperature in the surface of the heat workpiece by the analytical model in this work has a good match with the finite element simulation and the experimental results and the errors are reasonable and acceptable considering the inevitable factors. It is also obviously that the computing time of the analytical model is much less than the finite element simulation model. Thus, it is believed that the analytical model established in this paper can be used to predict the temperature evolution in the planar scanning induction heating and extends this heating method to a broader application, which has less computational time and experimental complexity.

The role and mechanism of lncRNA NEAT1 in the fibrosis of pulmonary epithelial cell

Hui Xu,YanBo Chen,Jinqiang Zhuang,Shun Zhu,Bing Xu,Jiang Hong 대한독성 유전단백체 학회 2020 Molecular & cellular toxicology Vol.16 No.2

Background Pulmonary fibrosis is a serious clinical fatal disease. Epithelial–mesenchymal transition (EMT) and lncRNA NEAT1 have been implied in its development and progression. Objective To study the role of lncRNA NEAT1 in the progression of fibrosis in human pulmonary epithelial cells (BEAS- 2B). Specifically, BEAS-2B was transfected with NEAT1 and miR-29c, EMT and cell proliferation were measured and the expression level of relevant genes was determined by Western blot. Result Results showed that NEAT1 promotes fibrosis and proliferation of BEAS-2B cells via the up-regulation of α-SMA, Vimentin, Snail and proliferation-related genes including Cyclin D1 and Cyclin E; miR-29c is a target gene of NEAT1 and through which NEAT1 regulates EMT and expression of proliferation-related genes. Conclusion This study investigated the mechanism of pulmonary fibrosis progression by elucidating the role of NEAT1/ miR-29c in the fibrosis and proliferation of BEAS-2B cells, thus providing a basis for the new therapeutic targets of pulmonary fibrosis.