Improved Vibration Suppression Modeling for Reinforcement Clamping by Eco-friendly Magnetorheological Fluid During Milling of Annular Thin-Walled Workpiece

Xiaohui Jiang,Kun Wu,Yong Zhang,Shirong He 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.6

Milling vibration will greatly affect the milling accuracy and surface quality of thin-walled workpiece. Considering that the characteristics of instant curing high-efficiently under the action of magnetic field and can be recycled without wasted of magnetorheological fluid (MRF), a MRF composite clamping to suppress milling vibration is proposed in this paper. Based on the fluid–solid coupling dynamics theory, the dynamics modal of the MRF clamping is established. On this basis, considering the influences of the filling volume of MRF to processing vibration, the suppression effect of MRF on milling vibration is analyzed in time domain and frequency domain, respectively. A series of simulations and experiments are carried out on typical annular thin-walled workpiece, the result shows that the maximum increase of natural frequency of thin-walled workpiece is 53.1% while filling with MRF, and Ra, Rz, Rq decreased by 36.1%, 14.8% and 16.7%, respectively. The consequence verified the reliability and effectiveness of the proposed method in the whole milling process.

Segmentation of the Synthetic Aperture Radar Image Using the Watershed Transformation and Region Merging Technique

Chuanxian Jiang,Zhiping Li,Xiaohui Chen,Zejun Zhang,Yeqing Yi 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.9

This paper presents an efficient algorithm that segments the synthetic aperture radar (SAR) image into several homogeneous regions by combining edge- and region-based information. A multi-direction ratio edge detector is used to capture the locally directional variation information of a SAR image and construct the ratio edge strength map (RESM) of the SAR image. Watershed transformation is performed on the thresholded RESM to obtain an over-segmentation result. An efficient hierarchical region merging procedure based on the region adjacency graph representation of the image regions is proposed. A novel dissimilarity measurement between the two adjacent regions is derived from the multiplicative noise speckle model of the multi-look SAR image. Experimental results and the performance evaluation show that the proposed method outperforms two widely used SAR image segmentation approaches.

The influence of mesh misalignment on the dynamic characteristics of helical gears including sliding friction

Hanjun Jiang,Yimin Shao,Chris K. Mechefske,Xiaohui Chen 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.11

Due to either elastic deformations or errors in the manufacturing or assembling of gears, shafts, bearings and their housings, it is an inevitableconsequence that mesh misalignment between teeth occurs. The change in length of the contact line or the change in load distributionalong the length of the contact line induced by mesh misalignment causes changes in the dynamic characteristics of helical gears. There is currently no satisfactory solution for the modeling and calculation of the internal excitation in helical gears with mesh misalignmentand sliding friction that would reveal the changes in the dynamic characteristics. In this study, an improved calculation method offriction excitation is proposed based on the time-varying length of the contact line and the time-varying friction coefficient model in helicalgears. By considering the change in the mesh position and the change in the length of the contact line or the change of the displacementerror along the contact line induced by mesh misalignment, the time-varying sliding friction force and the dynamic mesh force maybe obtained. An eight degree-of-freedom analytical helical gear pair model is developed by incorporating the time-varying sliding frictionforce and dynamic mesh force and considering the mesh misalignment. By assuming a constant mesh stiffness density along the contactline, the rules governing the variation of the dynamic response are obtained using simulations of helical gear pair examples with differentfriction coefficient models and mesh misalignment. The developed analytical model provides a new method for the study of excitationcharacteristics in helical gears with mesh misalignment.

Enhanced anticorrosion of methyl acrylate by covalent bonded N-alkylpyridinium bromide for X70 steel in 5 M HCl

Guangqiang Xia,Xiaohui Jiang,Limei Zhou,Yinwen Liao,Ming Duan,Hu Wang,Qiang Pu,Jie Zhou 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.27 No.-

Methyl acrylate connects covalently with alkylpyridinium bromide to build N-alkyl-3-(2-methox-ycarbonyl-vinyl)pyridinium bromide (MPA-n, n = 8–14). MPA-n inhibited X70 steel from corrosion in5 M HCl with inhibition efficiency of 98% and the inhibition capacity was in the order of MPA-14 > MPA-12 > MPA-10 > MPA-8. Quantum chemical calculation unveiled that MPA-n adsorbed on iron surface byO atom in MA moiety offering electrons to d orbital of iron and by p* orbital of pyridinium acceptingelectrons from iron, and MPA-n with longer alkylchain possessed higher EHOMO, lower DE, largermolecular volume and dipole moment, all suggesting the same corrosion inhibition order as that inexperiments

Discovery of an Enormous Ly<i>α</i>Nebula in a Massive Galaxy Overdensity at<i>z</i>= 2.3

Cai, Zheng,Fan, Xiaohui,Yang, Yujin,Bian, Fuyan,Prochaska, J. Xavier,Zabludoff, Ann,McGreer, Ian,Zheng, Zhen-Ya,Green, Richard,Cantalupo, Sebastiano,Frye, Brenda,Hamden, Erika,Jiang, Linhua,Kashikawa, American Astronomical Society 2017 The Astrophysical journal Vol.837 No.1

<P>Enormous Ly alpha nebulae (ELANe), unique tracers of galaxy density peaks, are predicted to lie at the nodes and intersections of cosmic filamentary structures. Previous successful searches for ELANe have focused on wide-field narrowband surveys or have targeted known sources such as ultraluminous quasi-stellar objects (QSOs) or radio galaxies. Utilizing groups of coherently strong Ly alpha absorptions, we have developed a new method to identify high-redshift galaxy overdensities and have identified an extremely massive overdensity, BOSS1441, at z = 2-3. In its density peak, we discover an ELAN that is associated with a relatively faint continuum. To date, this object has the highest diffuse Ly alpha nebular luminosity of L-nebula = 5.1 +/- 0.1 x 10(44) erg s(-1). Above the 2 sigma surface brightness limit of SBLy alpha = 4.8 x 10(-18) erg s(-1) cm(-2) arcsec(-2), this nebula has an end-to-end spatial extent of 442 kpc. This radio-quiet source also has extended C IV lambda 1549 and He II lambda 1640 emission on greater than or similar to 30 kpc scales. Note that the Ly alpha, He II, and C IV emissions all have double-peaked line profiles. Each velocity component has an FWHM of approximate to 700-1000 km s(-1). We argue that this Lya nebula could be powered by shocks due to an active galactic nucleus-driven outflow or photoionization by a strongly obscured source.</P>

Mapping the Most Massive Overdensities through Hydrogen (MAMMOTH). II. Discovery of the Extremely Massive Overdensity BOSS1441 at<i>z</i>= 2.32

Cai, Zheng,Fan, Xiaohui,Bian, Fuyan,Zabludoff, Ann,Yang, Yujin,Prochaska, J. Xavier,McGreer, Ian,Zheng, Zhen-Ya,Kashikawa, Nobunari,Wang, Ran,Frye, Brenda,Green, Richard,Jiang, Linhua American Astronomical Society 2017 The Astrophysical journal Vol.839 No.2

<P>Cosmological simulations suggest a strong correlation between high optical-depth Lya absorbers, which arise from the intergalactic medium, and 3D mass overdensities on scales of 10-30 h(-1) comoving Mpc. By examining the absorption spectra of similar to 80,000 QSO sight lines over a volume of 0.1 Gpc(3) in the Sloan Digital Sky Survey III (SDSS-III), we have identified an extreme overdensity, BOSS1441, which contains a rare group of strong Lya absorbers at z = 2.32 +/- 0.02. This absorber group is associated with six QSOs at the same redshift on a 30 comoving Mpc scale. Using Mayall/MOSAIC narrowband and broadband imaging, we detect Lya emitters (LAEs) down to 0.7 x L-Ly alpha ' * a and reveal a large-scale structure of LAEs in this field. Our follow-up LBT observations have spectroscopically confirmed 20 galaxies in the density peak. We show that BOSS1441 has an LAE overdensity of 10.8 +/- 2.6 on a 15 comoving Mpc scale, which could collapse to a massive cluster with M greater than or similar to 10(15) M-circle dot at z similar to 0. This overdensity is among the most massive large-scale structures at z similar to 2 discovered to date.</P>

Refining Characteristics of Hardwood Pulp Using Straight- and Curved-bar Plates: A Time Series Study

Huan Liu,Jixian Dong,Xiaojun Jiang,Chong Luo,Xiaohui Tian,Ruifang Yang,Litao Zhang,Bo Wang,Yan Yan 한국펄프·종이공학회 2019 펄프.종이기술 Vol.51 No.5

There are obvious differences in the refining characteristics of plates with straight bars compared to curved bar plates having the same bar parameters during refining. The objective of this research is to explore the difference in the refining characteristics of the straight bar and curved bar plates on experimental and theoretical studies. The bar angle of the curved bar plate is defined, and the two plates are used in the refining of bleached sulphate eucalyptus pulp (BSEP). Samples at different refining times were collected, and the properties of the fibers, pulp, and paper were detected and analyzed. It was found that the curved bar and straight bar plates have a similar influence on the pulp SR freeness. However, the curved bar plate effectively retained the fiber length, which means that its fiber cutting effect is weaker than that of the straight bar plate. Meanwhile, the fiber external fibrillation of the samples refined by the curved bar plate was better than that of the samples refined by the straight bar, which showed a higher tensile and tear index of the formed paper. Through the theoretical analysis of refining intensity via characterization of the parameter bar edge length (BEL), the specific edge load (SEL) of the curved bar plate was lower, and the refining characteristics predicted by the refining intensity were similar to the results from the experiments conducted in this paper.

Fabrication of Unique and Green Tin(IV) Sulfide/Moss Photocatalyst for Highly Effective Photocatalytic Reduction of Cr(VI)

Xia Zhang,Yumin Wang,Chao Hou,Xiaohui Lin,Hongli Jiang,Zhenhua Wei 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.3

We report a simple and green method for fabricating SnS2 modified moss composites for removal of heavy metal (Cr(VI)) considering the fact that the issue of wastewater caused by the discharge of heavy metal is becoming increasingly serious. More importantly, this kind of functional materials that are capable of removing effectively Cr(VI) from wastewater for water purification is quite few on the market. Hence, in the paper, such SnS2 decorated moss photocatalysts for removal of heavy metal (Cr(VI)) were designed and prepared via a simple and green method: chemical bath reaction. The as-designed materials (C@SnS2) integrate the independent properties of moss (with excellent performance in absorption of heavy metal) and SnS2 (with good photocatalytic reduction of Cr(VI) under visible light irradiation), showing a faster photocatalytic rate than those independent components. The experiment results indicate that more than 98.5% of Cr(VI) was reduced under visible light irradiation for 70 min, while only 18.2% and 84.4% of Cr(VI) were removed in the presence of C-moss and pure SnS2 at the same condition, respectively. Furthermore, the as-designed C@SnS2 has good recyclability in the removal of Cr(VI). We believe such simple and green method to prepare photocatalyst for wastewater treatment with excellent performance will provide a good platform to design new photocatalytic materials for water purification.

Soft switching circuit of high-frequency active neutral point clamped inverter based on SiC/Si hybrid device

Wang, Jianing,Xun, Yuanwu,Liu, Xiaohui,Yu, Shaolin,Jiang, Nan The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

Although the silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) is superior to the conventional silicon (Si) insulated gate bipolar transistor in terms of switching performance, the switching losses of SiC devices increase rapidly by hard switching when the switching frequency (f_sw) increase to hundreds of kilohertz (kHz). This paper proposes an auxiliary zero-voltage-transition circuit to realize zero-voltage-switching for all of the high-frequency main switches of the active neutral point clamped (ANPC) inverter based on a SiC/Si hybrid device, and zero-current-switching for all of the auxiliary switches. Through soft switching, the switching losses and anti-parallel diode reverse recovery losses of high-frequency SiC MOSFET switches can be further reduced. First, the circuit topology and the operation principle of the soft switching are detailed followed by the design procedure of the parameters. Then, the efficiencies of hard switching and soft switching ANPC inverters are compared with f_sw changing from 10 to 200 kHz. To further improve the efficiency of the soft-switching inverter, two improved methods are proposed. The two proposed methods are auxiliary switches paralleling the external diode and utilizing synchronous rectification technology. Finally, a 1 kW, up to 200 kHz frequency ANPC inverter has been built to validate the above analysis.

Hippo signaling is intrinsically regulated during cell cycle progression by APC/C^Cdh1

Kim, Wantae,Cho, Yong Suk,Wang, Xiaohui,Park, Ogyi,Ma, Xueyan,Kim, Hanjun,Gan, Wenjian,Jho, Eek-hoon,Cha, Boksik,Jeung, Yun-ji,Zhang, Lei,Gao, Bin,Wei, Wenyi,Jiang, Jin,Chung, Kyung-Sook,Yang, Yingzi National Academy of Sciences 2019 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.116 No.19

<P><B>Significance</B></P><P>The Hippo signaling pathway is evolutionarily conserved in the animal kingdom and plays essential roles in regulating tissue growth during development and regeneration. We have identified APC/C<SUP>Cdh1</SUP>, a core component of cell cycle control machinery, as an evolutionarily conserved and previously unknown regulator of large tumor suppressor (LATS) kinases, which critically inhibit the YAP/TAZ transcription factors in transducing Hippo signaling. Our results suggest a model that APC/C<SUP>Cdh1</SUP> destabilizes LATS1/2 kinases in G1 phase of the cell cycle, leading to increased YAP/TAZ activities that promote G1/S transition by upregulating downstream gene expression, including <I>E2F1</I>. Our findings have important implications for a link between cell proliferation and LATS-regulated YAP/TAZ activities.</P><P>The Hippo-YAP/TAZ signaling pathway plays a pivotal role in growth control during development and regeneration and its dysregulation is widely implicated in various cancers. To further understand the cellular and molecular mechanisms underlying Hippo signaling regulation, we have found that activities of core Hippo signaling components, large tumor suppressor (LATS) kinases and YAP/TAZ transcription factors, oscillate during mitotic cell cycle. We further identified that the anaphase-promoting complex/cyclosome (APC/C)<SUP>Cdh1</SUP> E3 ubiquitin ligase complex, which plays a key role governing eukaryotic cell cycle progression, intrinsically regulates Hippo signaling activities. CDH1 recognizes LATS kinases to promote their degradation and, hence, YAP/TAZ regulation by LATS phosphorylation is under cell cycle control. As a result, YAP/TAZ activities peak in G1 phase. Furthermore, we show in <I>Drosophila</I> eye and wing development that Cdh1 is required in vivo to regulate the LATS homolog Warts with a conserved mechanism. Cdh1 reduction increased Warts levels, which resulted in reduction of the eye and wing sizes in a Yorkie dependent manner. Therefore, LATS degradation by APC/C<SUP>Cdh1</SUP> represents a previously unappreciated and evolutionarily conserved layer of Hippo signaling regulation.</P>