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.

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.

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.

Neural network adaptive position tracking control of underactuated autonomous surface vehicle

ChengJu Zhang,Cong Wang,Yingjie Wei,JinQiang Wang 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.2

The present study investigates the position tracking control of the underactuated autonomous surface vehicle, which is subjected to parameters uncertainties and external disturbances. In this regard, the backstepping method, neural network, dynamic surface control and the sliding mode method are employed to design an adaptive robust controller. Moreover, a Lyapunov synthesis is utilized to verify the stability of the closed-loop control system. Following innovations are highlighted in this study: (i) The derivatives of the virtual control signals are obtained through the dynamic surface control, which overcomes the computational complexities of the conventional backstepping method. (ii) The designed controller can be easily applied in practical applications with no requirement to employ the neural network and state predictors to obtain model parameters. (iii) The prediction errors are combined with position tracking errors to construct the neural network updating laws, which improves the adaptation and the tracking performance. The simulation results demonstrate the effectiveness of the proposed position tracking controller.

Antimonene prepared by laser irradiation applied for nonlinear optical limiting

Weili Shen,Jinning Hu,Teng Ma,Jiaxin Wang,Yi Wei,Yuanzhou Zhang,Jinqiang Wu,Jun Chen 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.6

Antimonene, a novel two-dimension (2D) Group-VA material, shows excellent electrical and optical properties. In this work,antimonene nanosheets or nanoparticles were obtained by laser irradiating antimony powder in isopropanol solution anddiff erent morphology of antimonene were obtained by adjusting diff erent laser irradiation parameters, including irradiationtime and irradiation energy. The nonlinear absorption properties of antimonene with diff erent morphologies under 532 nmnanosecond laser were studied by Z-scan technology. It was found that the reverse-saturation absorption ability was thestrongest when the morphology of the sample was nanosheets, which was very suitable for optical limiting. In addition, dueto the limitation of the application of the sample in the form of solution, we added it into organosilicon, and obtained thesolid antimonene-organosilicon composite with optical limiting function. The results showed that antimonene nanosheetswith best optical limiting ability can be prepared by adjusting the laser irradiation parameters, and the products are successfullyadded into solid matrix to enhance its practicability in protecting people’s eyes and optical equipment from damagecaused by high power laser.

Two-Dimensional Unilamellar Cation-Deficient Metal Oxide Nanosheet Superlattices for High-Rate Sodium Ion Energy Storage

Xiong, Pan,Zhang, Xiuyun,Zhang, Fan,Yi, Ding,Zhang, Jinqiang,Sun, Bing,Tian, Huajun,Shanmukaraj, Devaraj,Rojo, Teofilo,Armand, Michel,Ma, Renzhi,Sasaki, Takayoshi,Wang, Guoxiu American Chemical Society 2018 ACS NANO Vol.12 No.12

<P>Cation-deficient two-dimensional (2D) materials, especially atomically thin nanosheets, are highly promising electrode materials for electrochemical energy storage that undergo metal ion insertion reactions, yet they have rarely been achieved thus far. Here, we report a Ti-deficient 2D unilamellar lepidocrocite-type titanium oxide (Ti<SUB>0.87</SUB>O<SUB>2</SUB>) nanosheet superlattice for sodium storage. The superlattice composed of alternately restacked defective Ti<SUB>0.87</SUB>O<SUB>2</SUB> and nitrogen-doped graphene monolayers exhibits an outstanding capacity of ∼490 mA h g<SUP>-1</SUP> at 0.1 A g<SUP>-1</SUP>, an ultralong cycle life of more than 10000 cycles with ∼0.00058% capacity decay per cycle, and especially superior low-temperature performance (100 mA h g<SUP>-1</SUP> at 12.8 A g<SUP>-1</SUP> and −5 °C), presenting the best reported performance to date. A reversible Na<SUP>+</SUP> ion intercalation mechanism without phase and structural change is verified by first-principles calculations and kinetics analysis. These results herald a promising strategy to utilize defective 2D materials for advanced energy storage applications.</P> [FIG OMISSION]</BR>