A modified JFNK with line search method for solving k-eigenvalue neutronics problems with thermal-hydraulics feedback

Liu Lixun,Zhang Han,Wu Yingjie,Liu Baokun,Guo Jiong,Li Fu 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.1

The k-eigenvalue neutronics/thermal-hydraulics coupling calculation is a key issue for reactor design and analysis. Jacobian-free Newton-Krylov (JFNK) method, featured with super-linear convergence rate and high efficiency, has been attracting more and more attention to solve the multi-physics coupling problem. However, it may converge to the high-order eigenmode because of the multiple solutions nature of the k-eigenvalue form of multi-physics coupling issue. Based on our previous work, a modified JFNK with a line search method is proposed in this work, which can find the fundamental eigenmode together with thermal-hydraulics feedback in a wide range of initial values. In detail, the existing modified JFNK method is combined with the line search strategy, so that the intermediate iterative solution can avoid a sudden divergence and be adjusted into a convergence basin smoothly. Two simplified 2-D homogeneous reactor models, a PWR model, and an HTR model, are utilized to evaluate the performance of the newly proposed JFNK method. The results show that the performance of this proposed JFNK is more robust than the existing JFNK-based methods

Optimum path-tracking control for inverse problem of vehicle handling dynamics

Yingjie Liu,Junsheng Jiang 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.8

A method based on optimal control theory is presented in this paper to solve path-tracking problems in inverse vehicle handling dynamics. The idea behind is to identify the optimal steering torque input along a prescribed path to generate an expected trajectory that guarantees minimum clearance. Based on this purpose, the path-tracking problem, treated as an optimal control problem, is first converted into a nonlinear programming problem by Gauss pseudospectral method (GPM) and is then solved with Sequential quadratic programming (SQP). Finally, a real vehicle test is executed to verify the rationality of the proposed model and methodology. Results show that the minimum lateral position error of the generated path-tracking trajectory can be a good solution for path-tracking problem in inverse vehicle handling dynamics for GPM. The algorithm has higher calculation accuracy compared with other methods to solve pathtracking problems. The study could help drivers identify safe lane-keeping trajectories and areas easily.

An Improved Privacy Preserving Construction for Data Integrity Verification in Cloud Storage

( Yingjie Xia ),( Fubiao Xia ),( Xuejiao Liu ),( Xin Sun ),( Yuncai Liu ),( Yi Ge ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.10

The increasing demand in promoting cloud computing in either business or other areas requires more security of a cloud storage system. Traditional cloud storage systems fail to protect data integrity information (DII), when the interactive messages between the client and the data storage server are sniffed. To protect DII and support public verifiability, we propose a data integrity verification scheme by deploying a designated confirmer signature DCS as a building block. The DCS scheme strikes the balance between public verifiable signatures and zero-knowledge proofs which can address disputes between the cloud storage server and any user, whoever acting as a malicious player during the two-round verification. In addition, our verification scheme remains blockless and stateless, which is important in conducting a secure and efficient cryptosystem. We perform security analysis and performance evaluation on our scheme, and compared with the existing schemes, the results show that our scheme is more secure and efficient.

Risk Degree of Ship-bridge Collision based on Theory of Ship Collision Avoidance

Yihua Liu,Yingjie Xiao 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.11

Bridges have played an integral role in the development of economy and progress of human society, which facilitate transportation and promote regional economic development. However, a large number of bridges for sea-crossing or river-crossing have impeded the water transportation to varying degrees, and then one part of bridges are confronted with higher risk of ship-bridge collision. There are many ship-bridge collision accidents in the world in recent decades, which caused huge casualties and property losses. This paper proposes the model of risk degree for ship-bridge collision based on the theory of ship collision avoidance, as one parts of the system of active warning of ship-bridge collision avoidance, which can show the index of dynamic risk degree for vessels passing through bridge area. The index of ship-bridge collision can make more efficiency for the system of active warning of ship-bridge collision avoidance, which can ensure safety for vessels and bridges. The verification results show the application possibility of the model in practice.

Establishment of an efficient regeneration system using heading leaves of Chinese cabbage (Brassica rapa L.) and its application in genetic transformation

Weixin Liu,Yingjie Yang,Qianqian Liu 한국원예학회 2018 Horticulture, Environment, and Biotechnology Vol.59 No.4

To preserve and propagate valuable Chinese cabbage (Brassica rapa L.) using mature vegetative organs without seeds, we established a high efficiency regeneration system from heading leaf explants and further explored its application in genetic transformation. Our results showed that maximum shoot regeneration of cultivars ‘Beijing New No. 3’ (88.46 ± 1.65%) and ‘Chengyangqing’ (73.77 ± 1.73%) were obtained in the presence of 17.76 μM 6-benzylaminopurine (BA) and 5.37 μM α-naphthylacetic acid (NAA). The addition of silver nitrate (AgNO3) at 11.77 μM was essential for shoot regeneration from heading leaf explants. Genotypic differences in shoot regeneration frequencies (from 47.24 ± 3.65 to 88.46 ± 1.65%) were observed amongst eight Chinese cabbage cultivars, in addition to the number of shoots per explant (from 1.31 ± 0.02 to 2.02 ± 0.05) in Murashige and Skoog medium containing 17.76 μM BA, 5.37 μM NAA and 11.77 μM AgNO3. Low temperature (4 °C) had an effect on in vitro preservation of leafy heads with a delay in leaf wilting, and there were no significant differences in shoot induction frequency within 24 h for cultivars ‘Beijing New No. 3’ and ‘Chengyangqing’. In the genetic transformation experiments using selection with kanamycin (17.17 μM), a transformation efficiency of 0.6–1.2% was achieved, as assessed from PCR and Southern blot results. The above results suggested that the heading leaf explants can not only achieve efficient seed-independent propagation of Chinese cabbage, but also provide a feasible platform for genetic transformation.

Study on Emporium Airflow Optimization in View of Cooling Load Distribution Indoor

LV Ziqiang,Liu Yingjie 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.1

Large load and high energy consumption is the characteristics of air-conditioning in shopping malls. For most of these shopping malls which are in excessively high energy consumption were accompanied by unreasonable airflow forms. This work measured the lighting and body cooling load at three shopping malls, analyzed lighting and body cooling load on the different floors ,different lighting area, then compared the measured value and the design manual recommended values, According to the results of analysis, recommended values is wrong. A personalized airflow forms is proposed according to the actual personnel distribution of the shopping mall; the plan of ceiling exhaust is proposed according lighting heat dissipation, the ventilation efficiency of air conditioning systems proved be significantly increased after the improvements of airflow form, it provide an effective reference to design air conditioning system for these types of shopping malls.

Complex Vector Modeling and Series Decoupling Current Control Strategy of High-Power L/LCL Type Grid-Connected Converter Under Low Switching Frequency

Yingjie Wang,Lanyi Jiao,Bo Yang,Wenchao Wang,Haiyuan Liu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

With power level of grid-connected converters rising, the switching frequency of the switching devices is commonly greatly reduced to improve its power capacity. However, this results in serious couplings of the dq current components, which leads to degradation of the static and dynamic performances of grid-connected converters and fluctuations of the reactive power in dynamic processes. In this paper, complex vector models under low switching frequency are established for an L/LCL grid-connected converter, and the relationship between the switching frequency and the coupling degree is analyzed. In addition, a series decoupling current control strategy is put forward. It is shown that the proposed control strategy can eliminate the couplings, improve the performances and have good robustness to parameter variations through static and dynamic characteristics analyses and a sensitivity analysis. Experimental and simulation results also verify the correctness of the theoretical analyses and the superiority of the proposed control strategy.

A PI Control Algorithm with Zero Static Misadjustment for Tracking the Harmonic Current of Three-Level APFs

Yingjie He,Jinjun Liu,Zhaoan Wang,Yunping Zou 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1

Tracking harmonic current quickly and precisely is one of the keys to designing active power filters (APF). In the past, the current state feedback decoupling PI control was an effective means for three-phase systems in the current control of constant voltage constant frequency inverters and high frequency PWM reversible rectifiers. This paper analyzes in detail the limitation of the conventional PI conditioner in the APF application field and presents a novel PI control method. Canceling the delay of one sampling period and the misadjustment for tracking the harmonic current is the key problem of this PI control. In this PI control, the predictive output current value is obtained by a state observer. The delay of one sampling period is remedied in this digital control system by the state observer. The predictive harmonic command current value is obtained by a repetitive predictor synchronously. The repetitive predictor can achieve better predictions of the harmonic current. By this means, the misadjustment of the conventional PI control for tracking the harmonic current is cancelled. The experiment results with a three-level NPC APF indicate that the steady-state accuracy and dynamic response of this method are satisfying when the proposed control scheme is implemented.

Research on Driving Cycle of Long-distance Passenger Vehicles Based on Principal Component Analysis and Cluster Algorithm

Yingji Liu,Jingyi Li,Bo Shen 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.3

Multiple Decoupling Current Control Strategies for LCL Type Grid-Connected Converters Based on Complex Vectors under Low Switching Frequencies

Liu, Haiyuan,Shi, Yang,Guo, Yinan,Wang, Yingjie,Wang, Wenchao The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

In medium-voltage and high-voltage high-power converters, the switching devices need to operate at a low switching frequency to reduce power loss and increase the power capacity. This increases the delay of the signal sampling and PWM. It also makes the cross-couplings of the d-q current components more severe. In addition, the LCL filter has three cross-coupling loops and is prone to resonance. In order to solve these problems, this paper establishes a complex vector model of an LCL type grid-connected converter. Based on this model, two multiple decoupling current control strategies with passive damping / notch damping are proposed for the LCL type grid-connected converter. The proposed strategies can effectively eliminate the cross-couplings of the converter, achieve independent control of the d-q current components, expand the stable region and suppress the resonance of the LCL filter. Simulation and experimental results verify the correctness of the theoretical analysis and the feasibility of the proposed strategies.