Inverse Design of Flow Distortion Dominated by Shock Wave Interaction with Experimental Verification

Kaikai Yu,Peng Su,Yile Chen,Jinglei Xu 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.4

With the development of supersonic/hypersonic vehicles, the influence of non-uniform flow has attracted increasing attention. Non-uniform flow exists everywhere in a scramjet, which is a potent engine for supersonic/hypersonic vehicles. Most flows entering the isolator, combustor, and nozzle exhibit high non-uniformity. Thus, several design methods for generating non-uniform flow have been proposed. However, these design methods cannot simulate flow distortion with high accuracy, especially the non-uniform flow caused by shock wave interaction. Thus, a design method for distortion generators, which can generate non-uniform flow associated with flow deflection angles, is proposed in this study to mimic the shock wave-dominated non-uniform flow with shock wave interaction. Numerical simulation and experiment are adopted to verify the effectiveness and reliability of the proposed method. The Mach number on the outlet and the surface pressure distribution on the upper wall of the distortion generator obtained in the experiment show a good agreement with the target one.

Decoupling Control Analysis of a Flux Reversal Linear Rotary Permanent Magnet Actuator

Kaikai Guo,Youguang Guo,Jingzhao Li 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4

In order to meet the requirement of industrial production, a control system of a novel fux reversal linear rotary permanent magnet actuator (FR-LRPMA) is developed in this paper, and the electromagnetic and motion decoupled process is analyzed in detail. Firstly, the control equation of FR-LRPMA is derived in the nine phase stator coordinate system and dual dq-axis mover coordinate system. Then the control model of FR-LRPMA is built in MATLAB/Simulink using improved space vector pulse width modulation (SVPWM), and the linear, rotary and spiral motions of the proposed actuator are achieved. Finally, the prototype of the actuator is manufactured, and the experiment platform of FR-LRPMA is set up to measure the cogging torque and linear detent force, validating the simulation results. It is concluded that the control system of FR-LRPMA can be converted into two independent single freedom motors by dual dq transformation. The improved SVPWM is efective in the control system, and the method can be used to solve the electromagnetic and motion decoupling problems.

Magnetorheology of suspensions based on graphene oxide coated or added carbonyl iron microspheres and sunflower oil

Chen, Kaikai,Zhang, Wen Ling,Shan, Lei,Zhang, Xiangjun,Meng, Yonggang,Choi, Hyoung Jin,Tian, Yu American Institute of Physics 2014 JOURNAL OF APPLIED PHYSICS - Vol.116 No.15

Design and Analysis of an Outer Mover Linear-Rotary Vernier Machine

Guo Kaikai,Guo Youguang 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

According to the requirements of large torque and high precision linear displacement of the drilling robot, an outer mover (OM) linear-rotary (LR) vernier machine (VM) is proposed with a special support mechanism, which combines an outer rotor VM and a cylindrical OM linear VM. In order to reduce the detent force and improve the displacement accuracy of the linear motion when the proposed motor works at low speed and short stroke conditions, the modular stators and permanent magnet poles are adopted instead of the traditional toroid structure. Since the torque is the main output quantity and the linear motion mainly determines the linear displacement, the design of the rotary unit is taken as the optimization objective fi rstly. Then, the cogging torque and detent force of OMLRVM are added to the optimization objectives. The electromagnetic and mechanical designs of the proposed motor are calculated based on 3-D fi nite element model. Compared with the results of the initial topologies I and II, the end eff ects of rotary and linear units are reduced thanks to the support mechanism, and the amplitudes of cogging torque and detent force are decreased. The idea of combined electromagnetic and mechanical design is an eff ective way to solve the practical application problems in industrial fi eld.

The Effects of Surfactants on the Spinnability, Structure and Properties of Dry-jet Wet Spinning Poly(m-phenylene isophalamide) Fiber

Qianli Liu,Kaikai Cao,Shikai Qi,You Yang,Shuheng Liang,Huihui Gao,Chen Yang,Dazhe Li,Mengjin Jiang 한국섬유공학회 2020 Fibers and polymers Vol.21 No.7

The spinnability of semi-dilute poly(m-phenylene isophalamide) (PMIA) spinning dope was regulated by a smallamount of surfactants to make it suitable for dry-jet wet spinning. OP-10 shows the best effect of lowering the surface tensionof PMIA spinning dope among the selected surfactants. The effects of different amounts of OP-10 on surface tension andrheological behavior of PMIA spinning dope were investigated. Results show that when the content of OP-10 reaches0.5 wt.%, the surface tension of the PMIA dope reduces to a minimum. The apparent viscosity of the PMIA dope increaseswith the increment of OP-10 contents. The dynamic viscoelasticity study shows that OP-10 also enhances the elasticity of thePMIA spinning dope. The spinning dope with 0.5 wt.% OP-10 can be smoothly spun by dry-jet wet spinning, and theobtained PMIA filament shows excellent mechanical performance.

Discussion of Sensitivity Factors and Dominating Variable for Design Value Method

Jitao Yao,Kaikai Cheng 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.1

The partial factor method is considered to be one of the most reliable design methods. However, engineers have examined the shortcomings of the partial factor method, primarily its flexibility and generality in searching for the values of partial factors. In order to improve upon the partial factor method, the design value method has been established on the basis of probability. The design value method is more flexible, general, and represents the developing direction of the reliability design method. However, based on experience, a set of sensitivity factors αi values has been developed. The sum of squares may be greater than 1.0 as a result of conservatism. Although some researchers have revised the values of αi by using the enumeration optimization method, the results are not ideal. This paper focuses on the recommended values of sensitivity factors that are applicable to the safety design as well as the serviceability design. It will be shown that these recommended values can improve the accuracy of the reliability index and present specific ranges of relative errors. This makes it possible to establish a practical design value method based on probability. In addition, a method to determine the dominating parameter is illustrated.

Chemerin reverses the malignant phenotype and induces differentiation of human hepatoma SMMC7721 cells

Ming Li,Pengcheng Sun,Kaikai Dong,Ye Xin,Aslee TaiLulu,Qinyu Li,Jing Sun,Min Peng,Ping Shi 대한약학회 2021 Archives of Pharmacal Research Vol.44 No.2

Chemerin exhibits an inhibitory eff ect on hepatocellularcarcinoma; however, the underlying mechanismis unclear. Here, low chemerin expression was confi rmedin samples of liver cancer patients and hepatoma cells. Chemerin altered hepatoma cell morphology but had noeff ect on normal hepatocytes. Chemerin inhibited proliferationof several human hepatoma cell lines. Real-time PCRdetection of hepatocellular carcinoma markers showed thatmRNA levels of albumin and A-type gamma-glutamyltransferase increased whereas those of alpha-fetoprotein,alkaline phosphatase, B-type gamma-glutamyl transferase,insulin-like growth factor II, and human telomerase reversetranscriptase decreased in chemerin-treated SMMC7721cells. Western blotting revealed that chemerin up-regulatedalbumin and vimentin expressions, and downregulated alpha-fetoprotein expression. Phosphorylated STAT3 wassignifi cantly up-regulated, whereas phosphorylated ERKand AKT were signifi cantly downregulated by chemerin. Chemerin decreased phosphorylated ERK and AKT expressionand the cell proliferation induced by PI3K activator 740Y-P but could not signifi cantly alter phosphorylated STAT3expression and the cell growth induced by STAT3 inhibitorNSC74859. In conclusion, chemerin reversed the malignantphenotype and induced SMMC7721 cell diff erentiation byinhibiting MAPK/ERK and PI3K/AKT signaling; growthinhibition by chemerin is not directly related to the JAK/STAT signaling pathway. Our study provides novel evidencethat chemerin could be utilized for liver cancer treatment.

A Lifetime-Preserving and Delay-Constrained Data Gathering Tree for Unreliable Sensor Networks

( Yanjun Li ),( Yueyun Shen ),( Kaikai Chi ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.12

A tree routing structure is often adopted for many-to-one data gathering and aggregation in sensor networks. For real-time scenarios, considering lossy wireless links, it is an important issue how to construct a maximum-lifetime data gathering tree with delay constraint. In this work, we study the problem of lifetime-preserving and delay-constrained tree construction in unreliable sensor networks. We prove that the problem is NP-complete. A greedy approximation algorithm is proposed. We use expected transmissions count (ETX) as the link quality indicator, as well as a measure of delay. Our algorithm starts from an arbitrary least ETX tree, and iteratively adjusts the hierarchy of the tree to reduce the load on bottleneck nodes by pruning and grafting its sub-tree. The complexity of the proposed algorithm is O(N⁴). Finally, extensive simulations are carried out to verify our approach. Simulation results show that our algorithm provides longer lifetime in various situations compared to existing data gathering schemes.

Neonicotinoid insecticide resistance in the field populations of Sogatella furcifera (Horváth) in Central China from 2011 to 2015

Xiaolei Zhang,Xun Liao,Kaikai Mao,Peng Yang,Dongyang Li,Ehsan Ali,Hu Wan,Jian Hong Li 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.3

The whitebacked planthopper Sogatella furcifera (Horváth) is an important pest of rice throughout Asia. Application of chemical insecticide is the main approach to suppress the field populations of S. furcifera. In this study, neonicotinoid insecticide resistance in field populations of S. furcifera were evaluated. The results showed that some field populations of S. furcifera had developed moderate level of resistance to imidacloprid (RR =1.1–16.4), thiamethoxam (RR=0.8–14.9), dinotefuran (RR =1.2–16.6) and acetamiprid (RR =3.3–12.2), low level of resistance to nitenpyram (RR=1.1–9.5) and clothianidin (RR =1.3–8.7) in Central China. Moreover, there were an increasing trend in neonicotinoid insecticide resistance in the period 2011–2015. The results of current study may form the basis to identify and evaluate the resistance tendency of S. furcifera against neonicotinoid insecticides, which could make effective management recommendations to avoid further development of insecticide resistance in S. furcifera.

Effects of short-term soil tillage management on activity and community structure of denitrifiers under double-cropping rice field

Haiming Tang,Chao Li,Kaikai Cheng,Lihong Shi,Li Wen,Xiaoping Xiao,Yilan Xu,Weiyan Li,Ke Wang 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.11

Soil physical and chemical characteristics, soil potential denitrification rates (PDR), community composition and nirK-, nirS- and nosZ-encoding denitrifiers were studied by using MiSeq sequencing, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment polymorphism (T-RFLP) technologies base on short-term (5-year) tillage field experiment. The experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue retention (NT), and rotary tillage with crop residue removed as control (RTO). The results indicated that soil organic carbon, total nitrogen and NH4 +-N contents were increased with CT, RT and NT treatments. Compared with RTO treatment, the copies number of nirK, nirS and nosZ in paddy soil with CT, RT and NT treatments were significantly increased. The principal coordinate analysis indicated that tillage management and crop residue returning management were the most and the second important factors for the change of denitrifying bacteria community, respectively. Meanwhile, this study indicated that activity and community composition of denitrifiers with CT, RT and NT treatments were increased, compared with RTO treatment. This result showed that nirK, nirS and nosZ-type denitrifiers communities in crop residue applied soil had higher species diversity compared with crop residue removed soil, and denitrifying bacteria community composition were dominated by Gammaproteobacteria, Deltaproteobacteria, and Betaproteobacteria. Therefore, it is a beneficial practice to increase soil PDR level, abundance and community composition of nitrogen-functional soil microorganism by combined application of tillage with crop residue management.