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Changqing Shen,Yuminghao Xiao,Liangshan Xiong 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.4
In the present study, a novel grinding wheel design method is proposed to design a wheel for grinding different small helical grooves on the existing helical rake faces of the tool. The proposed method can be applied to manufacture tools with uneven helical rake face like zigzag-edge twist drills. In the proposed method, the processing of the non-wedge groove is initially converted into a superposition of processing steps of several wedge grooves. Then, based on the simplified non-thickness grinding wheel parametric design and envelop graphic design, the grinding wheel capable of processing small wedge grooves with various specified shapes can be obtained. Moreover, through establishing quantitative evaluation criteria, the determination of design parameters concerning the non-thickness grinding wheel is transmitted into an optimization problem. Finally, helical grooves with trapezoid truncation and wedge truncations are simulated on a virtual five-axis machine tool to verify the effectiveness of the grinding wheel design method.
Stochastic elastic wave analysis of angled beams
Changqing Bai,Hualin Ma,Victor P.W. Shim 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.5
The stochastic finite element method is employed to obtain a stochastic dynamic model of angled beams subjected to impact loads when uncertain material properties are described by random fields. Using the perturbation technique in conjunction with a precise time integration method, a random analysis approach is developed for efficient analysis of random elastic waves. Formulas for the mean, variance and covariance of displacement, strain and stress are introduced. Statistics of displacement and stress waves is analyzed and effects of bend angle and material stochasticity on wave propagation are studied. It is found that the elastic wave correlation in the angled section is the most significant. The mean, variance and covariance of the stress wave amplitude decrease with an increase in bend angle. The standard deviation of the beam material density plays an important role in longitudinal displacement wave covariance.
Changqing Ren,Fugui He,Xianzhi Gao,Dongsheng Wu,Wenli Yao,Jianzhang Tian,Huiping Guo,Yuanxin Huang,Li Wang,Han Feng,Junwei Li 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.6
The Shulu Sag which is a rifted sag with NNE trend is located in the south of Jizhong Depression, Bohai Bay Basin, northern China. The gentle slope and three troughs are situated in the west and east of the sag, respectively. Both of the lower part of Shasan Member (Es3x) and the lower part of Shayi Member (Es1x) act as source rocks in this sag. Researches on the type, quantity, quality and thermal maturity of the respective organic matter have been conducted using Rock-Eval pyrolysis data. Type II is the dominant kerogen in Es1x of all troughs. However, Type II1 and III is the dominant kerogen in Es3x of Middle-Southern and Northern trough, respectively. TOC (total organic carbon) and pyrolysis S2 (hydrocarbon) values suggest that the Es1x source rocks in Middle-Southern and Northern trough are fair to good and poor to fair generative potential of hydrocarbon, separately. The Es3x source rocks in Middle-Southern and Northern trough possess fair to excellent and poor to fair generative potential of hydrocarbon, individually. Tmax (pyrolysis temperature at maximum S2) values indicate that most of Es3x samples are thermally mature, but all Es1x samples are thermally immature. Under large scale condition, the hydrocarbon secondary migration in the upper part of Shasan Member (Es3s), Shaer Member (Es2) and the upper part of Shayi Member (Es1s) have been simulated using fluid potential model with Arcgis 9.3 software. The simulation results reveal the direction of hydrocarbon secondary migration and the distribution of hydrocarbon migration-accumulation units (HMAUS), and also suggest that the hydrocarbon migration direction is obviously controlled by nose-like structure belts where most of hydrocarbons accumulate. That shows high reliability because they are consistent with the hydrocarbon exploration result in this area. On the basis of integrated analyses of source rocks and hydrocarbon migration direction, the following five areas in the gentle slope are identified to be the preferred hydrocarbon accumulation area: Taijiazhuang area, northern and southern Xicaogu area, as well as northern and southern Leijiazhuang area. It is considerably helpful to reduce the risk in hydrocarbon exploration of Shulu Sag.
Changqing Wu,Feng Chen,James W. Rushing,Xi Wang,김현진,George Huang,Vivian Haley-Zitlin,Guoqing He 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.1
The medicinal herb feverfew [Tanacetum parthenium (L.) Schultz-Bip.] has long been used as a folk remedyfor the treatment of migraine and arthritis. Parthenolide, a sesquiterpene lactone, is considered to be the primary bioactivecompound in feverfew having anti-migraine, anti-tumor, and anti-inflammatory properties. In this study we determined, throughin vitrobioassays, the inhibitory activity of parthenolide and golden feverfew extract against two human breast cancer celllines (Hs605T and MCF-7) and one human cervical cancer cell line (SiHa). Feverfew ethanolic extract inhibited the growthof all three types of cancer cells with a half-effective concentration (EC50) of 1.5 mg/mL against Hs605T, 2.1 mg/mL againstMCF-7, and 0.6 mg/mL against SiHa. Among the tested constituents of feverfew (i.e., parthenolide, camphor, luteolin, andapigenin), parthenolide showed the highest inhibitory effect with an EC50 against Hs605T, MCF-7, and SiHa of 2.6 .g/mL,2.8 .g/mL, and 2.7 .g/mL, respectively. Interactions between parthenolide and flavonoids (apigenin and luteolin) in fever-few extract also were investigated to elucidate possible synergistic or antagonistic effects. The results revealed that apigeninand luteolin might have moderate to weak synergistic effects with parthenolide on the inhibition of cancer cell growth ofHs605T, MCF-7, and SiHa.
Heritable Epigenetic Variation and its Potential Applications for Crop Improvement
( Changqing Zhang ),( Tzung Fu Hsieh ) 한국육종학회 2013 Plant Breeding and Biotechnology Vol.1 No.4
Phenotypic variation within organisms is driven primarily by genetic diversity. However, there is a growing appreciation that epigenetic variation, resulting from a multitude of diverse chemical modifications to the DNA and chromatin, can have profound effects on phenotype. Heritable epigenetic marks persist through meiosis and can be stably transmitted to the next generation, resulting in transgenerational epigenetic inheritance. Importantly, when epigenetic changes occur near coding genes, affecting their transcriptional state, heritable epigenetic variation can result in heritable phenotypic variation. Large-scale interrogation of epigenome inheritance in Arabidopsis has revealed that spontaneous variation in DNA methylation occurs at a rate that is orders of magnitude greater than genetic mutation, indicating the key importance of epigenetic variation during evolution. Thus, there is a potential for epigenetics to play a role in crop improvement, including regulation of trans gene expression and creation of novel epialleles. Here, we review cases of naturally occurring and genetically induced epialleles, and discuss how the studies from two epigenetic populations are rapidly increasing our understanding of epigenetic diversity.
Opportunistic Decode-and-Forward Cooperation in Mixed Rayleigh and Rician Fading Channels
Changqing Yang,Wenbo Wang,Shuang Zhao,Mugen Peng 한국전자통신연구원 2011 ETRI Journal Vol.33 No.2
We consider a two-hop multiple-relay network implemented with opportunistic decode-and-forward cooperative strategy, where the first hop and second hop links experience different fading (Rayleigh and Rician). We derive the exact expressions of end-to-end outage probability and analyze the approximate results in high signal-to-noise ratio region. The analysis shows that the same diversity order can be achieved even in different mixed fading environments. Simulation results are provided to verify our analysis.
Analysis on the dynamic characteristics of RAC frame structures
Changqing Wang,Jianzhuang Xiao 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.4
The dynamic tests of recycled aggregate concrete (RAC) are carried out, the rate-dependent mechanical models of RAC are proposed. The dynamic mechanical behaviors of RAC frame structure are investigated by adopting the numerical simulation method of the finite element. It is indicated that the lateral stiffness and the hysteresis loops of RAC frame structure obtained from the numerical simulation agree well with the test results, more so for the numerical simulation which is considered the strain rate effect than for the numerical simulation with strain rate excluded. The natural vibration frequency and the lateral stiffness increase with the increase of the strain rate. The dynamic model of the lateral stiffness is proposed, which is reasonably applied to describe the effect of the strain rate on the lateral stiffness of RAC frame structure. The effect of the strain rate on the structural deformation and capacity of RAC is analyzed. The analyses show that the inter-story drift decreases with the increase of the strain rate. However, with the increasing strain rate, the structural capacity increases. The dynamic models of the base shear coefficient and the overturning moment of RAC frame structure are developed. The dynamic models are important and can be used to evaluate the strength deterioration of RAC structure under dynamic loading.
Seismic Analysis on Recycled Aggregate Concrete Frame Considering Strain Rate Effect
Changqing Wang,Jianzhuang Xiao,Zhenping Sun 한국콘크리트학회 2016 International Journal of Concrete Structures and M Vol.10 No.3
The nonlinear behaviors of recycled aggregate concrete (RAC) frame structure are investigated by numerical simulation method with 3-D finite fiber elements. The dynamic characteristics and the seismic performance of the RAC frame structure are analyzed and validated with the shaking table test results. Specifically, the natural frequency and the typical responses (e.g., storey deformation, capacity curve, etc.) from Model 1 (exclusion of strain rate effect) and Model 2 (inclusion of strain rate effect) are analyzed and compared. It is revealed that Model 2 is more likely to provide a better match between the numerical simulation and the shaking table test as key attributes of seismic behaviors of the frame structure are captured by this model. For the purpose to examine how seismic behaviors of the RAC frame structure vary under different strain rates in a real seismic situation, a numerical simulation is performed by varying the strain rate. The storey displacement response and the base shear for the RAC frame structure under different strain rates are investigated and analyzed. It is implied that the structural behavior of the RAC frame structure is significantly influenced by the strain rate effect. On one hand, the storey displacements vary slightly in the trend of decreasing with the increasing strain rate. On the other hand, the base shear of the RAC frame structure under dynamic loading conditions increases with gradually increasing amplitude of the strain rate.