EFFECT OF FLASH ANNEALING ON MAGNETIC PROPERTIES OF Fe - BASED NANOCRYSTALLINE ALLOYS

Xiaojun Yu,Baiyun Quan,Guiqin Sun,Kenji Narita 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5

A heat-treatment method of pre-annealing and then flash annealing(FA) has been used to improve the soft magnetic properties of nanocrystalline Fe_(76)CuSi₁₃B_(10) and Fe_(74)CuNb₃Si₁₂B_(10) alloys. Outstanding magnetic properties of nanocrystalline Fe_(74)CuNb₃Si₁₂B_(10) alloy were attained by flash-annealing in air after annealed at 500℃ for 0.5hr below the crystallization temperature. The same results were obtained for Fe_(74)CuSi₁₃B_(10) alloy. The measurment of relief of stress and X-ray diffraction were used to analyze the effect of flash-annealing.

Theoretical Study on the Mechanism of the Addition Reaction between Cyclopropenylidene and Formaldehyde

Xiaojun Tan,Zhen Li,Qiao Sun,Ping Li,Weihua Wang 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.6

The reaction mechanism between cyclopropenylidene and formaldehyde has been systematically investigated employing the MP2/6-311+G* level of theory to better understand the cyclopropenylidene reactivity with carbonyl compound. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are further corrected by the CCSD(T)/6-311+G* single-point calculations. It was found that one important reaction intermediate (INTa) has been located firstly via a transition state (TSa). After that, the common intermediate (INTb) for the two pathways (1) and (2) has been formed via TSb. At last, two different products possessing three- and four-membered ring characters have been obtained through two possible reaction pathways. In the reaction pathway (1), a three-membered ring alkyne compound has been obtained. As for the reaction pathway (2), it is the formation of the four-membered ring conjugated diene compound. The energy barrier of the ratedetermining step of pathway (1) is lower than that of the pathway (2), and the ultima product of pathway (2) is more stable than that of the pathway (1).

An improved design of power-cycling hydrodynamic mechanical transmission

Xiaojun Liu,Dongye Sun 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8

Recent studies have demonstrated that the power-cycling hydrodynamic mechanical (PCHM) transmission has excellent performance in improving power performance and fuel economy of a wheel loader. However, these results have been obtained by assuming that its speed ratio can always change continuously. Hence, this study first investigated the speed ratio of the transmission how to change when shifting from one gear to another. It was found that the concept of the PCHM transmission suggested in the literature is ineffective, even for a configuration with two gears in the gearbox. Then, the configuration of the PCHM transmission was developed as a different one to increase the torque multiplication capacity and efficiency of the transmission. A design method for this transmission is proposed to quantify its performances. The design method is based on a multi-objective optimization problem which is comprised of two objectives, seven design variables and eleven constraints. The relationships between average efficiency of the transmission and maximum tractive force of the vehicle and the seven transmission parameters are qualitatively examined. Results show that the performance of the transmission depends mainly on the number of transmission gears instead of on three parameters of the torque converter. The average efficiency is not sensitive to the maximum tractive force on a globally optimal Pareto front. The PCHM transmission with the new configuration can enable the average efficiency and the maximum tractive force to increase by 2.1 % and by 6.6 %, compared to that of the traditional hydrodynamic mechanical transmission, respectively.

Differential Expression of miR-34c and Its Predicted Target Genes in Testicular Tissue at Different Development Stages of Swine

Xiaojun Zhang,Wei Zhao,Chuanmin Li,Haibin Yu,YanYan Qiao,Aonan Li,Chunyan Lu,Zhihui Zhao,Boxing Sun 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.11

To verified the target genes of miR-34c, bioinformatics software was used to predict the targets of miR-34c. Three possible target genes of miR-34c related to spermatogenesis and male reproductive development: zinc finger protein 148 (ZNF148), kruppel-like factor 4 (KLF4), and platelet-derived growth factor receptor alpha (PDGFRA) were predicted. Then, the expression of miR-34c and its target genes were detected in swine testicular tissue at different developmental stages by quantitative polymerase chain reaction. The results suggested that the expression of PDGFRA has the highest negative correlation with miR-34c. Then immunohistochemical staining was done to observe the morphology of swine testicular tissue at 2-days and 3, 4, 5-months of age, which indicated that PDGFRA was mainly expressed in the support cells near the basement membrane during the early development stages of testicular tissue, but that the expression of PDGFRA was gradually reduced in later stages. Therefore, western blot analyzed that the highest expression of PDGFRA was generated in 2-days old testicular tissues and the expression levels reduced at 3 and 4-months old, which correlated with the results of immunohistochemical staining. In conclusion, PDGFRA is a target gene of miR-34c.

Sensitivity analysis and parameter interval optimization for residual stress in polishing process of GH4169 blisk blade

Xiaojun Lin,Xiaopeng Xin,Rui Yang,Zhaozhao Lei,Luzhou Sun,Bao Yang,Changyou Bai,Yangwei Yan 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2

Surface integrity has a significant impact on the performance and life cycle of the blisk blade. Residual stress, as one of the important characterization parameters of surface integrity, is closely related to the performance of the aeroengine blisk blade. A certain interval of residual compressive stress can significantly inhibit the generation of microcracks. This paper proposes an optimization method of polishing process parameter interval based on sensitivity analysis. This research studied the effect of polishing parameters of the alumina ACW (abrasive cloth wheel) on the surface residual stress of the GH4169 superalloy blisk blade. Firstly, the experiment was designed by four factors and three levels response surface method, the multiple regression of the experimental data based on Minitab software was used to get a prediction model of polished surface residual stress. And an analysis of variance was performed on the model. Subsequently, the model of relative sensitivity was got based on this model. The sensitivity order of polishing surface residual stress to each polishing parameter was obtained. And the judging method of stable interval and instable interval was put forward. Then, a parameter interval optimization method was proposed, and the optimal interval of process parameters was obtained. Finally, a polishing verification experiment was performed. The results show that: for the polishing of GH4169 superalloy blades, the surface residual stress is most sensitive to the feed rate vf of the ACW, followed by the granularity p and the rotation rate ω, and the compression depth ap is the least sensitive. The optimal interval of polishing process parameters is: the rotation rate ω is [11000 r/min, 11500 r/min], the feed rate vf is [100 mm/min, 200 mm/min], the compression depth ap is [0.6 mm, 1.0 mm], and the granularity p is [400 #, 600 #]. The optimized polishing process parameters can obtain a large and stable surface residual compressive stress, which is helpful to increase fatigue strength of the blisk blade.

Differential Expression of miR-34c and Its Predicted Target Genes in Testicular Tissue at Different Development Stages of Swine

Zhang, Xiaojun,Zhao, Wei,Li, Chuanmin,Yu, Haibin,Qiao, YanYan,Li, Aonan,Lu, Chunyan,Zhao, Zhihui,Sun, Boxing Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.11

To verified the target genes of miR-34c, bioinformatics software was used to predict the targets of miR-34c. Three possible target genes of miR-34c related to spermatogenesis and male reproductive development: zinc finger protein 148 (ZNF148), kruppel-like factor 4 (KLF4), and platelet-derived growth factor receptor alpha (PDGFRA) were predicted. Then, the expression of miR-34c and its target genes were detected in swine testicular tissue at different developmental stages by quantitative polymerase chain reaction. The results suggested that the expression of PDGFRA has the highest negative correlation with miR-34c. Then immunohistochemical staining was done to observe the morphology of swine testicular tissue at 2-days and 3, 4, 5-months of age, which indicated that PDGFRA was mainly expressed in the support cells near the basement membrane during the early development stages of testicular tissue, but that the expression of PDGFRA was gradually reduced in later stages. Therefore, western blot analyzed that the highest expression of PDGFRA was generated in 2-days old testicular tissues and the expression levels reduced at 3 and 4-months old, which correlated with the results of immunohistochemical staining. In conclusion, PDGFRA is a target gene of miR-34c.

Theoretical Study on the Mechanism of the Addition Reaction between Cyclopropenylidene and Formaldehyde

Tan, Xiaojun,Li, Zhen,Sun, Qiao,Li, Ping,Wang, Weihua Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.6

The reaction mechanism between cyclopropenylidene and formaldehyde has been systematically investigated employing the MP2/6-311+$G^*$ level of theory to better understand the cyclopropenylidene reactivity with carbonyl compound. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are further corrected by the CCSD(T)/6-311+$G^*$ single-point calculations. It was found that one important reaction intermediate (INTa) has been located firstly $via$ a transition state (TSa). After that, the common intermediate (INTb) for the two pathways (1) and (2) has been formed $via$ TSb. At last, two different products possessing three- and four-membered ring characters have been obtained through two possible reaction pathways. In the reaction pathway (1), a three-membered ring alkyne compound has been obtained. As for the reaction pathway (2), it is the formation of the four-membered ring conjugated diene compound. The energy barrier of the ratedetermining step of pathway (1) is lower than that of the pathway (2), and the ultima product of pathway (2) is more stable than that of the pathway (1).

MICROCRYSTALLINE Fe - Si - Al - B THIN RIBBON

Guiqin Sun,Xiaojun Yu,Jikai Zhang,Kenji Narita 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5

By means of adding B into Sendust alloy (Fe-Si-Al) with state of amorphous ribbon, mechnical properties of alloy was improved effectively, and magnetic properties didn't decrease obviously. The optimum adding quantity of B is 0.015-0.03 wt%. The adding of B was thought to give rise to reduction of ordering degree of Fe₃(Si, Al) phase of Sedust alloy(Fe-Si-Al-B) and result in improvment of embrittlement of this alloy.

Experimental Study and Comfort Analysis of a New-type Precast Assembly Floor Under Human-induced Loads

Chongfang Sun,Shuting Liang,Xiaojun Zhu 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.7

In this paper, we have studied the comfort of a newly-designed precast assembly floor evaluated by acceleration response under human-induced loads. The influences of five cases including different rows of connectors, walking frequency, population size, walking route and distribution of people on the response of the floor are discussed. The results are as follows. The removed connectors at the middle span produce greater effect according to the influence of different rows of connectors. Greater walking frequency produces greater effect according to the influence of walking frequency. Larger population size produces greater effect according to the influence of population size. Walking in the direction perpendicular to the longitudinal direction of slabs and through the low-order mode center produces greater effect according to the influence of walking route. The case that people are distributed on both of the two conventional slabs produces greater effect according to the influence of distribution of people. For all the cases, their influence degrees are in the order of different rows of connectors, walking frequency, distribution of people, walking route, and population size. Finally, basing on the five cases and according to the Chinese design specification on the natural frequency and peak acceleration, the authors analyzes the comfort of the floor by selecting the most unfavorable condition, and verifies that it satisfies the terms in the specification. The newly-designed floor can be used in the future design of buildings.

Development and Analysis of Negative Stiffness Friction Damping Device

Tianwei Sun,Lingyun Peng,Xiaojun Li,Yingjie Kang,Yuke Deng 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.7

A new type of negative stiffness friction damping device (NSFDD) was developed in this study, which can solve the problem of poor energy dissipation of the existing passive negative stiffness damping device. The friction force is generated by squeezing the friction plate with the preloaded nitrogen spring vertically. When the NSFDD is working, the friction plate causes the nitrogen spring to rotate and negative stiffness force and friction force are generated. The results of the performance test show that the NSFDD can achieve negative stiffness in the hysteretic model. Comparing with the existing negative stiffness device, the NSFDD has larger stroke, more stable negative stiffness and better energy dissipation capacity. The finite element software has been used to simulate the low cycle reciprocation of a structure, and the results show that the NSFDD reduces the stiffness of the structure while increasing the damping of the structure. The results of the simulation and analysis of the shock absorption plan of the NSFDD show that the NSFDD reduces the stiffness of the floor, thereby effectively control on the shear force, displacement and acceleration response of the structure.