The Influence of the Economic Variables on the Chinese B-Share Markets

( Jiacheng Li ),( Seong-min Yoon ) 한중사회과학학회 2021 한중사회과학연구 Vol.19 No.1

This paper analyzed how economic variables affect the Chinese B-share market. For this purpose, we investigated the monthly data of major economic variables (consumer price index, imports and exports volume, money supply, real estate index and retail sales volume) and B-share price index of Shanghai and Shenzhen Exchange of China from 2009 to 2019 by employing the multivariate VAR-GARCH-BEKK model. We measured the return spillover effect between Chinese major economic variables and B-share market index from the estimation results of VAR conditional mean equation, and volatility spillover effect between the economic variables and B-share index from the estimation results of GARCH-BEKK conditional variance equation. From these results, we investigated whether there is any difference between the Shanghai and Shenzhen Exchange markets. The main findings are as follows. First, the return spillover effect does not exist in both markets except the Consumer Price Index (CPI). Second, there is the volatility spillover effect between economic variables and Shenzhen B-share market, implying that the volatility spillover effect is more important than the return spillover effect in the Chinese B-share market. Third, compared with Shanghai, the change of the Shenzhen stock market is more affected by the change of economic variables. These findings have some important policy implications. First, investors in Chinese stock market need to make good use of the information inherent in China’s economic changes to increase returns and reduce investment risks. Second, the investors should pay close attention to the overall trends of the Chinese economy and the global economy, not just to the trends of the Chinese market.

Impact of International Oil Prices on Chinese Renewable Energy, Agriculture, and Industrial Stock Prices

Jiacheng Li,동시 한중사회과학학회 2023 한중사회과학연구 Vol.21 No.4

The relationship between oil prices and sector stock prices may be nonlinear. This study explores how fluctuations in international oil prices affect China’s renewable energy, agricultural, and industrial stock prices. For this purpose, this study analyses WTI oil prices, four renewable energy stock indices, four agricultural stock indices, and four manufacturing stock indices spanning from August 2011 to October 2022. It employs a Granger causality test and a non-parametric quantile causality test. The main results are summarised as follows. Firstly, the two causality testing methods yielded different results, with the non-parametric quantitative causality test being more consistent with the expected results. Secondly, the stock prices of six of the 12 industries, including Chemical, Soybean, and Corn, show a clear correlation with oil prices, while the stock prices of the remaining six industries show no correlation with oil prices. Thirdly, the non-parametric quantile causality test results reveal that renewable energy stock prices in China are not dependent on international oil price changes. In addition, macroeconomic policies such as the industrial and employment policies of the government should also thoroughly consider the impact of oil price changes and the stock market situations.

Rotate vector reducer design using resnet-based model and integration of discretized optimization

Jiacheng Miao,Chaoyang Li,Xing Du,Bingkui Chen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

The author present an artificial intelligent (AI)-based deep generative model that demonstrate how to generate design options of mechanical systems, which are not only suitable for specific working conditions but also optimized for engineering performance. In current study, (1) a structural generative residual netowork (SG-Resnet) model is developed to establish the non-linear mapping between the working conditions and the external dimensions of the reducer, the main hyperparameters influencing the prediction ability and learning rate of the SG-Resnet are analyzed. (2) The mixed population non dominated sorting genetic algorithm-II (MP-NSGA-II) is proposed, and used to obtain pareto optimal solutions of the internal dimensions of the reducer. Experiments are performed to validate the positive effect of the structural generative model on the stiffness of the reducer. This research provides a novel method for reducer design and lays a solid foundation for the development of sequential engineering software for integrated rotate vector (RV) reducer.

Enhanced resistive switching performance of spinel MnCo2O4 resistive random access memory devices: Effects of annealing temperatures and annealing atmospheres

Du Ling,Li Jiacheng,Zhang Yu,Qin Ni,Bao Dinghua 한국물리학회 2023 Current Applied Physics Vol.48 No.-

The spinel MnCo2O4 (MCO) thin films were fabricated on Pt/Ti/SiO2/Si substrates for resistive memories via sol-gel spin-coating deposition method under different annealing temperatures and annealing atmospheres. The 650oC-annealing Pt/MCO/Pt device shows better bipolar resistance switching parameters than the devices annealed at 600 ◦C and 700 ◦C. The nitrogen-annealing Pt/MCO/Pt device exhibits optimum resistance switching parameters due to increasing of the oxygen-vacancies proportion, formation of confined and stable conductive filaments, and suppressing of the randomness of oxygen vacancies. The carrier transportation mechanisms of the devices with numerous oxygen-vacancies content in low resistance state (LRS) and high resistance state (HRS) are dominated by Ohmic conduction and Schottky emission, respectively. For the devices with fewer oxygen-vacancies content, the conduction mechanisms at LRS and HRS can be described by nearest-neighboring hopping conduction and space-charge-limited current model, respectively. This work indicates that the spinel MCO films have good potential application in resistive random access memory.

Crystallization Toughening of Fe-Based Amorphous Alloys Under Strain–Heat Coupling Effect

Wei Zhao,Jiacheng Yu,Mindong Hu,Honglei Hu,Junting Luo,Gong Li 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.1

The crystallization toughening of Fe-based amorphous alloys under strain–heat coupling effect was studied. This effectinvolved annealing crystallization along with uniform plastic deformation under three-direction compressive stress. Resultsshowed that the Fe-based amorphous alloys subjected to strain–heat coupling action had greater toughening effect than thosesubjected to single low-temperature annealing. The difference was due to the change in morphology of the precipitated crystalphase and the substantial amount of free volume introduced into an amorphous matrix through uniform plastic deformation,which was conducive to the proliferation of shear bands. However, excessive plastic deformation led to direct fracture ofmaterials after elastic deformation.

Fatigue characteristics of distributed sensing cables under low cycle elongation

Dan Zhang,Jiacheng Wang,Bo li,Bin Shi 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.6

When strain sensing cables are under long-term stress and cyclic loading, creep may occur in the jacket material and each layer of the cable structure may slide relative to other layers, causing fatigue in the cables. This study proposes a device for testing the fatigue characteristics of three types of cables operating under different conditions to establish a decay model for observing the patterns of strain decay. The fatigue characteristics of cables encased in polyurethane (PU), GFRP-reinforced, and wire rope-reinforced jackets were compared. The findings are outlined as follows. The cable strain decayed exponentially, and the decay process involved quick decay, slow decay, and stabilization stages. Moreover, the strain decay increased with the initial strain and tensile frequency. The shorter the unstrained period was, the more similar the initial strain levels of the strain decay curves were to the stabilized strain levels of the first cyclic elongation. As the unstrained period increased, the initial strain levels of the strain decay curves approached those of the first cyclic elongation. The tested sensing cables differed in the amount and rate of strain decay. The wire rope-reinforced cable exhibited the smallest amount and rate of decay, whereas the GFRP-reinforced cable demonstrated the largest.

Theoretical models of threshold stress intensity factor and critical hydride length for delayed hydride cracking considering thermal stresses

Jingyu Zhang,Jiacheng Zhu,Shurong Ding,Liang Chen,Wenjie Li,Hua Pang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.7

Delayed hydride cracking (DHC) is an important failure mechanism for Zircaloy tubes in the demandingenvironment of nuclear reactors. The threshold stress intensity factor, KIH, and critical hydride length, lC ,are important parameters to evaluate DHC. Theoretical models of them are developed for Zircaloy tubesundergoing non-homogenous temperature loading, with new stress distributions ahead of the crack tipand thermal stresses involved. A new stress distribution in the plastic zone ahead of the crack tip isproposed according to the fracture mechanics theory of second-order estimate of plastic zone size. Thedeveloped models with fewer fitting parameters are validated with the experimental results for KIH andlC. The research results for radial cracking cases indicate that a better agreement for KIH can be achieved;the negative axial thermal stresses can lessen KIH and enlarge the critical hydride length, so its effectshould be considered in the safety evaluation and constraint design for fuel rods; the critical hydridelength lC changes slightly in a certain range of stress intensity factors, which interprets the phenomenonthat the DHC velocity varies slowly in the steady crack growth stage. Besides, the sensitivity analysis ofmodel parameters demonstrates that an increase in yield strength of zircaloy will result in a decrease inthe critical hydride length lC , and KIH will firstly decrease and then have a trend to increase with the yieldstrength of Zircaloy; higher fracture strength of hydrided zircaloy will lead to very high values ofthreshold stress intensity factor and critical hydride length at higher temperatures, which might be themain mechanism of crack arrest for some Zircaloy materials

Anti-rollover of the counterbalanced forklift truck based on model predictive control

Guang Xia,Jiacheng Li,Xiwen Tang,Yang Zhang,Jinfang Hu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5

To reduce the probability of a rollover accident of a forklift during high-speed steering, a hydraulic support cylinder is designed as an actuator to provide lateral support for the forklift. Aiming at the problem of judging the safety domain in the process of forklift driving, this paper proposes a strategy for dividing the forklift’s driving state on the basis of the zero moment point. The relationship between the zero moment point’s lateral component and the forklift’s support plane is used as the basis for division. The forklift rollover process is divided into a safe stage, a controllable danger stage, and a critical rollover stage. In the safe stage, the cylinder does not provide support force, and in the controllable danger stage, the cylinder support force is adjusted on the basis of the model predictive control algorithm to adjust the forklift. The cylinder can be controlled to provide maximum support for the body during the critical rollover phase. This method takes the three-degrees-of-freedom forklift anti-rollover model as the control object and serves as the basis for the calculation of the zero moment point. The anti-rollover controller is built in MATLAB/Simulink to simulate the European standard operating conditions and to verify the actual vehicle test. Results show that the predictive control of the forklift anti-rollover model based on the zero moment point can effectively improve the body attitude of the forklift during high-speed steering and prevent the forklift from rolling over.

Study on Anti-Rollover of the Counterbalance Forklift Based on Extension Hierarchical Control

Xia Guang,Li Jiacheng,Tang Xiwen,Zhao Linfeng,Sun Baoqun 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.3

The anti-rollover control actuator of a counterbalance forklift is determined by analysing its structural characteristics and roll-over mechanism. An anti-rollover control strategy for counterbalance forklifts based on extension decision is proposed, and the anti-rollover extension hierarchical controller, including the upper-layer extension and lower-layer execution controls, is designed. The upper-layer extension controller divides the forklift anti-rollover control domain into three types, namely, classical domain, extension domain and non-domain, and determines the weight coefficient of the lower layer execution controller. The lower-layer execution controller receives the weight coefficient determined by the upper-layer extension controller, controls the weight distribution on the yaw rate and lateral acceleration controllers and executes the command to obtain the anti-rollover extension control of the counterbalance forklift. The European standard condition simulation and real vehicle test results show that the anti-rollover control strategy of the counterbalance forklift based on the extension decision can effectively reduce the forklift roll range under high-speed emergency steering conditions, prevent the forklift from rolling over and improve the stability and active safety of the counterbalance forklift.

Optimized junction temperature fluctuation suppression technique for SiC MOSFETs in a wireless charging system

Ruoyin Wang,Xueliang Huang,Jiacheng Li 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.5

The problem of SiC MOSFET junction temperature fluctuation in wireless charging systems must be addressed immediately. The existing temperature fluctuation suppression technique requires a large number of additional switches and capacitors. This study further optimizes the temperature fluctuation tracking suppression (TFTS) strategy. This method realizes closedloop temperature adjustment and greatly simplifies the system structure. In addition, an optimized TFTS (OTFTS) strategy combined with an optimized proportional–integral–derivative control method is proposed to solve integral saturation and the subsequent control instability phenomenon. Then, a 5.5 kW experimental system is built. Results show that the OTFTS strategy eliminates 17.9 °C junction temperature fluctuation on the basis of reducing the hardware cost. It also has a good dynamic response and junction temperature fluctuation suppression effect.