STUDY ON TRANSIENT FUEL HYDRODYNAMIC FORCE CHARACTERISTICS OF HIGH-SPEED SOLENOID VALVE FOR COMMON RAIL INJECTOR

Jianhui Zhao,Shunan Zhao,Leonid Grekhov 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.5

The working process of the high-speed solenoid valve (HSV) of high-pressure common rail (CR) injector has the characteristics of electro-magnetic-mechanical-hydrodynamic multi-physical field coupling. However, most of the research work in this field is carried out without considering hydrodynamic environment of the HSV. Furthermore, the dynamic response characteristics of the transient fuel hydrodynamic force (TFHF) of the HSV should not be neglected. In this study, a three-dimensional finite element method is used to simulate the TFHF between the injector electromagnet and the armature. The results show that cavitation phenomena appears on the lower surface of the armature during the HSV opening process. The faster the armature moves up, the greater the cavitation intensity. Damping holes on the armature can reduce the TFHF acting on the upper surface of the armature; however, the armature structure with straight grooves and damping holes reduces the TFHF more evidently during the HSV opening and the inhibition effect of this structure on cavitation is more evident. The TFHF on the armature decreases with an increase in the depth of the coil groove. However, the selection of the groove depth should be considered together with the optimization of the electromagnetic force characteristics of the HSV.

LIMIT OF FUEL INJECTION RATE IN THE COMMON RAIL SYSTEM UNDER ULTRA-HIGH PRESSURES

Jianhui Zhao,Leonid Grekhov,Pengfei Yue 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.3

The common rail injection system with higher injection pressure can improve injection characteristics. However, relevant researches for injection characteristics under ultra-high pressures are insufficient. In this article, the results of experiments with a maximum injection pressure of 390 MPa for nine different injectors of four types are presented. The experiment showed the existence of supercritical pressure during injection. At pressures below the supercritical pressure, the injection quantity increases with increasing injection pressure, however, when the injection pressure is over supercritical pressure, the injection quantity does not increase. According to the experiment results, the supercritical injection pressure is about 300 ~ 350 MPa. Under ultra-high pressures, fuel is strongly heated and the local sound velocity decreases, and the adiabatic flow velocity reaches the sound velocity. Under supercritical pressure, the injection rate ceases to increase and even begins to fall. The traditional equations for calculating the injection rate cannot correctly describe the injection under ultrahigh pressures. A new mathematic model with considering the fuel heating for describing the injection quantity of compressible fluid was developed, this model is not only suitable for calculating the injection quantity under ultra-high pressures, but under traditional injection pressures.

A new method to calculate the equivalent stiffness of the suspension system of a vehicle

Zhao, Pinbin,Yao, Guo-Feng,Wang, Min,Wang, Xumin,Li, Jianhui Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.3

The stiffness of a suspension system is provided by the bushings and the stiffness of the wheel center controls the suspension's elasto-kinematic (e-k) specification. So the stiffness of the wheel center is very important, but the stiffness of the wheel center is very hard to measure. The paper give a new method that we can use the stiffness of the bushings to calculate the equivalent stiffness of the wheel center, which can quickly and widely be used in all kinds of suspension structure. This method can also be used to optimize and design the suspension system. In the example we use the method to calculate the equivalent stiffness of the wheel center which meets the symmetric and positive conditions of the stiffness matrix.

The Similarity for Nominal Variables Based on F-Divergence

Zhao Liang,Liu Jianhui 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.3

Measuring the similarity between nominal variables is an important problem in data mining. It's the base to measure the similarity of data objects which contain nominal variables. There are two kinds of traditional methods for this task, the first one simply distinguish variables by same or not same while the second one measures the similarity based on co-occurrence with variables of other attributes. Though they perform well in some conditions, but are still not enough in accuracy. This paper proposes an algorithm to measure the similarity between nominal variables of the same attribute based on the fact that the similarity between nominal variables depends on the relationship between subsets which hold them in the same dataset. This algorithm use the difference of the distribution which is quantified by f-divergence to form feature vector of nominal variables. The theoretical analysis helps to choose the best metric from four most common used forms of f-divergence. Time complexity of the method is linear with the size of dataset and it makes this method suitable for processing the large-scale data. The experiments which use the derived similarity metrics with K-modes on extensive UCI datasets demonstrate the effectiveness of our proposed method.

Expression of FMD Virus-like particles in yeast Hansenula polymorpha and immunogenicity of combine with CpG and Alumimun adjuvant

Jianhui Zhang,Jun Ge,Juyin Li,Jianqiang Li,Yong Zhang,Yinghui Shi,Jiaojiao Sun,Qiongjin Wang,Xiaobo Zhang,Xing-xu Zhao 대한수의학회 2023 Journal of Veterinary Science Vol.24 No.1

Background: Inactivated vaccines are limited in preventing foot-and-mouth disease (FMD) due to safety problems. Recombinant virus-like particles (VLPs) are an excellent candidate for a novel vaccine for preventing FMD, given that VLPs have similar immunogenicity as natural viruses and are replication- and infection-incompetent. Objectives: The 3C protease and P1 polyprotein of type O FMD virus (FDMV) was expressed in yeast Hansenula polymorpha to generate self-resembling VLPs, and the potential of recombinant VLPs as an FMD vaccine was evaluated. Methods: BALB/c mice were immunized with recombinant purified VLPs using CpG oligodeoxynucleotide and aluminum hydroxide gel as an adjuvant. Cytokines and lymphocytes from serum and spleen were analyzed by enzyme-linked immunosorbent assay, enzyme-linked immunospot assay, and flow cytometry. Results: The VLPs of FMD were purified successfully from yeast protein with a diameter of approximately 25 nm. The immunization of mice showed that animals produced high levels of FMDV antibodies and a higher level of antibodies for a longer time. In addition, higher levels of interferon-γ and CD4+ T cells were observed in mice immunized with VLPs. Conclusions: The expression of VLPs of FMD in H. polymorpha provides a novel strategy for the generation of the FMDV vaccine.

Loss of Torque on Magnetic Fluid Seals with Rotating-shafts

Jianhui Hu,Meng Zhao,Lu Wang,Jibin Zou,Yong Li 한국자기학회 2017 Journal of Magnetics Vol.22 No.2

The effects of loss of torque on magnetic fluid seals with rotating-shafts and the general difficulty of studying magnetic fluid seals are the focus of this work. The mechanism underlying loss of torque on such seals is analyzed using theoretical methods that show that loss of torque can be affected by several factors, including the velocity of the rotating-shaft, the structure of the sealing device, the characteristics of the magnetic field, and the characteristics of the magnetic fluid. In this paper, a model of the loss of torque is established, and the results of finite element analysis and testing and simulations are analyzed. It is concluded that (ⅰ) the viscosity of the magnetic fluid increased with the intensity of the magnetic field within a certain range; (ⅱ) when the magnetic fluid was saturated, the increase in loss of torque tended to gradually slow down; and (ⅲ) although the axial active length of the magnetic fluid may decrease with increasing speed of the rotating-shaft, the loss of torque increased because of increasing friction.

Molecular Design of Photovoltaic Polymers for Efficient Organic Solar Cells

Jianhui HOU,Wenchao ZHAO,Shaoqing ZHANG,Huifeng YAO 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Commutation Compensation for Matrix based Rectifiers due to Leakage Inductances of Isolation Transformer

Tao Zhao,Jianhui Su,Dewei (David) Xu,Meiqin Mao 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes a compensation method for isolated matrix based rectifiers. The line side THD and output voltage isolated matrix rectifier are mainly affected by the commutation delay due to transformer leakage inductances. Since DC output voltage is usually regulated by a close loop controller. But the grid side current is affected by the commutation delay. The transformer leakage inductances increases the commutation delay which reduces actual dwell time of the active vector, causes distortion on grid side current with higher current THD. The proposed compensation method takes the commutation time into consideration and extends the dwell time for active vector properly. The algorithm has been verified by simulation results.

Performance Improvement of Finite Time Parameter Estimation with Relaxed Persistence of Excitation Condition

Li Zhao,Jianhui Zhi,Ningning Yin,Yong Chen,Jin Li,Jiaolong Liu 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.2

In this paper, a novel fi nite time parameter estimation method is proposed to solve the parameter estimation problem for a class of linearly parameterized nonlinear systems. The main feature of the proposed method is that the existing method is modifi ed via concurrent learning technique such that the strict persistence of excitation ( PE ) condition on the regression matrix is relaxed to a rank condition on the recorded data. This makes the presented method more practical. Furthermore, the convergence rate is improved signifi cantly by sliding mode technique in fi nite time sense. The simulation results of the existing general nonlinear system illustrate the aforementioned features. Comparison with existing methods from literature proves the eff ectiveness of the proposed method.

A new method to calculate the equivalent stiffness of the suspension system of a vehicle

Pinbin Zhao,Guo-feng Yao,Min Wang,Xumin Wang,Jianhui Li 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.3

The stiffness of a suspension system is provided by the bushings and the stiffness of the wheel center controls the suspension's elasto-kinematic (e-k) specification. So the stiffness of the wheel center is very important, but the stiffness of the wheel center is very hard to measure. The paper give a new method that we can use the stiffness of the bushings to calculate the equivalent stiffness of the wheel center, which can quickly and widely be used in all kinds of suspension structure. This method can also be used to optimize and design the suspension system. In the example we use the method to calculate the equivalent stiffness of the wheel center which meets the symmetric and positive conditions of the stiffness matrix.