Primary Carnitine Deficiency and Cardiomyopathy

Lijun Fu,Meirong Huang,Shubao Chen 대한심장학회 2013 Korean Circulation Journal Vol.43 No.12

Carnitine is essential for the transfer of long-chain fatty acids from the cytosol into mitochondria for subsequent β-oxidation. A lack of carnitine results in impaired energy production from long-chain fatty acids, especially during periods of fasting or stress. Primary carnitine deficiency (PCD) is an autosomal recessive disorder of mitochondrial β-oxidation resulting from defective carnitine transport and is one of the rare treatable etiologies of metabolic cardiomyopathies. Patients affected with the disease may present with acute metabolic decompensation during infancy or with severe cardiomyopathy in childhood. Early recognition of the disease and treatment with L-carnitine may be life-saving. In this review article, the pathophysiology, clinical presentation, diagnosis, treatment and prognosis of PCD are discussed, with a focus on cardiac involvements.

主題復現與情節圖式:≪醒世姻緣傳≫的結構詩學

부례군 ( Fu Lijun ) 중국어문연구회 2017 中國語文論叢 Vol.0 No.84

This paper explores the characteristics of the structural poetics of The Bonds of Matrimony, a 17th-century Chinese novel of 100 chapters. By focusing its analysis on the subplot concerning Xue Sujie, the female protagonist, this paper aims to offer a description of its plot pattern and an interpretation of the principle of plot construction in this novel. An analysis of the semantic content of the events in the subplot shows that the semantic content consists of four recurrent motifs and each motif can be related to a certain event in the subplot. The recurrence of the motifs helps to organize the events into a plot pattern. Hence the principle of plot construction in this novel can be described as repetition and variation of motifs. An examination of the female protagonist’s escalating conflicts with her environment reveals that the arc shape created by the rise and fall of her fortune coincides with the arc of the subplot. Therefore the pattern of the subplot can be seen as created by the traces of the female protagonist’s action.

Numerical Simulation of the Twist Deformation for the Stiffened Panel with Laser Forming

Shouchong Fu,Lijun Yang,Hongzhi Zhang,Yang Wang,Guanxin Chi,Ye Ding 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.10

In the laser forming process of the panel with crossed reinforcing bars (PWCRB), a kind of stiffened panel, twisting of the panel occurred when it was formed under the integral continuous scanning strategy (ICSS). The twisting was restrained obviously when the middle stiffener was heated. In order to reveal the twisting mechanism, a FE model was established and corresponding simulations were conducted. Furthermore, an equivalent model of the sectional structure was established, and a model of the buckling critical load of the stiffener was established based on principle of minimum potential energy. It revealed that the buckling critical load of the middle stiffener was smaller than that of the marginal stiffener. The simulation results showed that the stiffeners suffered from pressure and bending moment during the forming process, which tended to induce the buckling of the stiffeners. Besides, the residual stress of the middle stiffener was larger than that of the marginal stiffener. The bending angle of the middle stiffener increased when it was heated. Besides, the lateral-torsional deformation of the middle stiffener decreased and the twisting of the panel was restrained. It demonstrated that the twisting phenomenon of the PWCRB was caused by the middle stiffener, which suffered from lateral-torsional buckling when the panel was formed with the ICSS.

Analyses of Effects of Process Parameters on Laser Bending of Stiffened Panels

Shouchong Fu,Lijun Yang,Hongzhi Zhang,Yang Wang,Guanxin Chi 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.4

In this paper, laser forming technology was extended to form the stiffened panels. Compared with the plate with constant thickness, the stiffened panel was a type of panel with complicated structure and was hard to form. In order to gain a profound insight into the deformation characteristics of the stiffened panel under laser forming, a finite element model was established. The effects of process parameters on the deformation characteristics were investigated in terms of temperature distribution, stress and strain distribution. The influences of the process parameters on the unexpected deformation were analyzed by analyzing the influences of the process parameters on the maximum temperature theoretically. The results showed that laser spot diameter had the most important effect on the maximum temperature followed by the laser power and scanning speed. So when the scanning speed changed, the variation of the difference of the plastic strain between the top and bottom surface was the smallest.When the laser spot diameter decreased, the increment of the maximum temperature, the plastic strain as well as the deformation of the middle position of the scanning path was the largest. The increase of the deformation of the middle position of the scanning path could decrease the degree of the nonuniformity of the deformation of the free end, namely increasing the quality of the formed panel.

The Generator Excitation Control Based on the Quasi-sliding Mode Pseudo-variable Structure Control

Hu, Jian,Fu, Lijun The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

As an essential means of generator voltage regulation, excitation control plays an important role in controlling the stability of the power system. Therefore, the reasonable design of an excitation controller can help improve the system stability. In order to raise the robustness of the generator exciting system under outside interference and parametric perturbation and eliminate chattering in the sliding mode control, this paper presents a generator excitation control based on the quasi-sliding mode pseudo-variable structure control. A mathematical model of the synchronous generator is established by selecting its power, speed and voltage deviation as state variables. Then, according to the existing conditions of the quasi-sliding mode, a quasi-sliding mode pseudo-variable structure controller is designed, and the parameters of the controller are obtained with the method of pole configuration. Simulations show that compared with the existing methods, the proposed method is not only useful for accurate voltage regulation, but also beneficial to improving the robustness of the system at a time when perturbance happens in the system.

Stability Control of Energy Storage Voltage Source Inverters in Isolated Power Systems

Jian Hu,Lijun Fu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

Isolated power systems (IPS) are often characterized by a weak grid due to small power grids. The grid side voltage is no longer equivalent to an ideal voltage source of an infinitely big power grid. The conversion control of new energy sources, parameter perturbations as well as the load itself can easily cause the system voltage to oscillate or to become unstable. To solve this problem, increasing the energy-storage power sources is usually used to improve the reliability of a system. In order to provide support for the voltage, the energy-storage power source inverter needs an method to control the voltage source. Therefore, this paper has proposed the active damping control of a voltage source inverter (VSI) based on virtual compensation. By simplifying the VSI double closed-loop control, two feedback compensation channels have been constructed to reduce the VSI output impedance without changing the characteristics of the voltage gain of a system. This improvement allows systems to operate stably in a larger range. A frequency-domain analysis, and simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

Stability Control of Energy Storage Voltage Source Inverters in Isolated Power Systems

Hu, Jian,Fu, Lijun The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

Isolated power systems (IPS) are often characterized by a weak grid due to small power grids. The grid side voltage is no longer equivalent to an ideal voltage source of an infinitely big power grid. The conversion control of new energy sources, parameter perturbations as well as the load itself can easily cause the system voltage to oscillate or to become unstable. To solve this problem, increasing the energy-storage power sources is usually used to improve the reliability of a system. In order to provide support for the voltage, the energy-storage power source inverter needs an method to control the voltage source. Therefore, this paper has proposed the active damping control of a voltage source inverter (VSI) based on virtual compensation. By simplifying the VSI double closed-loop control, two feedback compensation channels have been constructed to reduce the VSI output impedance without changing the characteristics of the voltage gain of a system. This improvement allows systems to operate stably in a larger range. A frequency-domain analysis, and simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

SOC balance‑based decentralized control strategy for hybrid energy storage in integrated power systems

Xueping Gao,Lijun Fu,Yan Zhang,Feng Ji 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12

The hybrid energy storage systems (HESSs) in vessel integrated power systems can support pulse load and improve system stability. However, the unbalanced SOC of different energy storage devices can cause over-charge and over-discharge which damages the energy storage devices and affects the stable operation of the entire system, especially when there are multiple groups of HESSs. Therefore, a decentralized control strategy for the HESSs in integrated power systems (IPSs) based on extended droop control combined with SOC balance control is proposed in this paper. In the proposed strategy, SOC recovery control is introduced to the virtual capacitance droop coefficient of the supercapacitor, and SOC equalization control is introduced to the virtual resistance droop coefficient of the lithium battery to adjust the output characteristics of the HESS according to the SOC. Then the frequency response characteristics are analyzed and the stability of the system is calculated. Finally, the hardware in loop simulation is conducted to verify the effectiveness of the proposed strategy. Comparisons show that the proposed strategy can compensate for the pulse load according to the responding characteristics of the HESS and achieve SOC balance between different energy storage devices under various working conditions.

The Generator Excitation Control Based on the Quasi-sliding Mode Pseudo-variable Structure Control

Jian Hu,Lijun Fu 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

As an essential means of generator voltage regulation, excitation control plays an important role in controlling the stability of the power system. Therefore, the reasonable design of an excitation controller can help improve the system stability. In order to raise the robustness of the generator exciting system under outside interference and parametric perturbation and eliminate chattering in the sliding mode control, this paper presents a generator excitation control based on the quasi-sliding mode pseudo-variable structure control. A mathematical model of the synchronous generator is established by selecting its power, speed and voltage deviation as state variables. Then, according to the existing conditions of the quasi-sliding mode, a quasi-sliding mode pseudo-variable structure controller is designed, and the parameters of the controller are obtained with the method of pole configuration. Simulations show that compared with the existing methods, the proposed method is not only useful for accurate voltage regulation, but also beneficial to improving the robustness of the system at a time when perturbance happens in the system.

Molecular Dynamics Simulation of supercritical spray at micro & nano scale

( Zhang Yunxiao ),( Fu Qingfei ),( Mo Chaojie ),( Yang Lijun ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

The supercritical jets have many applications in many fields ranging from aerospace propulsion to chemical engineering. However, there is still lack of relevant theoretical research on the characteristics of supercritical fluids, and also lack of deep understanding of the destabilization mechanism of supercritical jets. Molecular dynamics method, which has been quite mature, can simulate extreme harsh physical conditions and exceptionally complex geometric model. The simulation process spontaneously contains all the physical effects. Therefore, the purpose of this paper is to study the characteristics and destabilization mechanism of supercritical jets from the microcosmic perspective using molecular dynamics method. Firstly, the molecular dynamics simulation of EOS (Equation of State) of liquid nitrogen was carried out. The influence of different simulation parameters on the simulation results was analyzed and then compared with the theoretical results. Four conditions were selected to study the influences of different time step, total simulation steps and truncation distance on the simulation results. The results show that the truncation distance has a great influence on the simulation precision, the time step and the total simulation steps have no significant impact on the EOS of liquid nitrogen. The results are in good agreement with the SRK (Soave-Redlich-Kwong) equation, which show the correctness of the simulation of supercritical fluids using molecular dynamics method. Secondly, the molecular dynamics simulation of supercritical nitrogen jet was carried out at different conditions. The supercritical jets ejected into a supercritical environment and a subcritical environment, respectively. Through the analysis of the results, the distribution of jet velocity, density, temperature and other jet characteristics was obtained. The interface was determined where concentration of supercritical fluid component reached 50% because the supercritical jet has no obvious vapor-liquid interface. Stable analysis of the results was performed and the disturbance growth rate of the supercritical shear layer at different conditions was obtained. Finally, the growth rate achieved by processing the results of molecular simulation was compared to the results by the linear stability analysis.