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| 1 | On-machine Precision Preparation and Dressing of Ball-headed Diamond Wheel for the Grinding of Fused Silica显示文摘In the grinding of high quality fused silica parts with complex surface or structure using ball-headed metal bonded diamond wheel with small diameter,the existing dressing methods are not suitable to dress the ball-headed diamond wheel precisely due to that they are either on-line in process dressing which may causes collision problem or without consideration for the effects of the tool setting error and electrode wear.An on-machine precision preparation and dressing method is proposed for ball-headed diamond wheel based on electrical discharge machining.By using this method the cylindrical diamond wheel with small diameter is manufactured to hemispherical-headed form.The obtained ball-headed diamond wheel is dressed after several grinding passes to recover geometrical accuracy and sharpness which is lost due to the wheel wear.A tool setting method based on high precision optical system is presented to reduce the wheel center setting error and dimension error.The effect of electrode tool wear is investigated by electrical dressing experiments,and the electrode tool wear compensation model is established based on the experimental results which show that the value of wear ratio coefficient K' tends to be constant with the increasing of the feed length of electrode and the mean value of K' is 0.156.Grinding experiments of fused silica are carried out on a test bench to evaluate the performance of the preparation and dressing method.The experimental results show that the surface roughness of the finished workpiece is 0.03 μm.The effect of the grinding parameter and dressing frequency on the surface roughness is investigated based on the measurement results of the surface roughness.This research provides an on-machine preparation and dressing method for ball-headed metal bonded diamond wheel used in the grinding of fused silica,which provides a solution to the tool setting method and the effect of electrode tool wear. | CHEN Mingjun LI Ziang YU Bo PENG Hui FANG Zhen | 2013 | Chinese Journal of Mechanical Engineering2013，26，5： | 5 |
| 2 | Promotional effect for SCR of NO with CO over MnO_(x)-doped Fe_(3)O_(4) nanoparticles derived from metal-organic frameworks显示文摘MnO_(x)-Fe_(3)O_(4) nanomaterials were fabricated by using the innovative scheme of pyrolyzing manganesedoped iron-based metal organic framework in inert atmosphere and exhibited extraordinary performance of NO reduction by CO(CO-SCR).Multi-technology characterizations were conducted to ascertain the properties of fabricated materials(e.g.,TGA,XRD,SEM,FT-IR,XPS,BET,H_(2)-TPR and O_(2)-TPD).Moreover,the interaction between reactants and catalysts was ascertained by in situ FT-IR.Experimental results demonstrated that Mn was an ideal promoter for iron oxides,resulting in decrease of crystallite size,improve reducibility property,enhance the mobility and the amount of lattice O^(2-) species,as well as strength the adsorption ability of active NO and CO to form multiple species(e.g.,nitrate and carbonate).The unprecedented enhancement of CO-SCR activity over Mn-Fe nanomaterials follows the Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)reaction pathway. | Yu Zhang Ling Zhao Ziang Chen Xinyong Li | 2022 | Chinese Journal of Chemical Engineering2022，35，6： | 4 |
| 3 | Prophet model and Gaussian process regressionbased user traffic prediction in wireless networks显示文摘User traffic prediction is an important topic for wireless network operators.A user traffic prediction method based on Prophet and Gaussian process regression is proposed in this paper.The proposed method first employs discrete wavelet transform to decompose the user traffic time series to high-frequency component and low-frequency component.The low-frequency component bears the long-range dependence of user network traffic,while the high-frequency component reveals the gusty and irregular fluctuations of user network traffic.Then Prophet model and Gaussian process regression are applied to predict the two components respectively based on the characteristics of the two components.Experimental results demonstrate that the proposed model outperforms the existing time series prediction method. | Yu LI Ziang MA Zhiwen PAN Nan LIU Xiaohu YOU | 2020 | Science China(Information Sciences)2020，63，4： | 4 |
| 4 | Control parallel double inverted pendulum by hierarchical reinforcement learning显示文摘 | Zheng Yu Luo Siwei Lv Ziang | 2004 | Signal Processing2004，2，： | 1 |
| 5 | Characterization of CoMn catalyst by in situ X-ray absorption spectroscopy and wavelet analysis for Fischer–Tropsch to olefins reaction显示文摘Cobalt carbide has recently been reported to catalyse the FTO con version of syngas with high selectivity for the production of lower olefins (C2-C4). Clarifying the formation process and atomic structure of cobalt carbide will help understand the catalytic mechanism of FTO. Herein, hydrogenati on of carb on monoxide was investigated for cobalt carbide synthesized from CoMn catalyst, followed by X-ray diffraction, transmission electron microscopy, temperature programmed reaction and in situ X-ray absorption spectroscopy. By monitoring the evolution of cobalt carbide during syngas conversion, the wavelet transform results give evidenee for the formation of the cobalt carbide and clearly demonstrate that the active site of catalysis was cobalt carbide. | Ruoou Yang Zhaoming Xia Ziang Zhao Fanfei Sun Xianlong Du Haisheng Yu Songqi Gu Liangshu Zhong Jingtai Zhao Yunjie Ding Zheng Jiang | 2019 | Journal of Energy Chemistry2019，28，5： | 0 |
| 6 | Climatic response of Pinus sylvestris var. mongolica tree-ring width and precipitation reconstruction for the northern Greater Higgnan Mountains, China, since 1720显示文摘August–June precipitation has been reconstructed back to AD 1720 for the northern Greater Higgnan Mountains, China, by use of Pinus sylvestris var. mongolica tree-ring width. The reconstruction explains the variance of 39% in observed precipitation from 1973 to 2008. Some extremely dry/wet signals in historical documents and other precipitation reconstructions in previous studies are precisely captured in our reconstruction. Wet periods occurred during the periods of 1730 to 1746, 1789 to 1812, 1844 to 1903, 1920 to 1930, 1942 to 1961, and 1985 to 1998; while periods of 1747 to 1788, 1813 to 1843, 1904 to 1919, 1931 to 1941, and 1962 to 1984 were relatively dry. Power spectral and wavelet analyses demonstrated the existence of significant 24-year, 12-year, and 2-year cycles of variability. | TongWen Zhang YuJiang Yuan WenShou Wei RuiBo Zhang ShuLong Yu Feng Chen HuaMing Shang Li Qin ZiAng Fan | 2014 | Research in Cold and Arid Regions2014，6，6： | 0 |
| 7 | Oxygen metabolism-balanced engineered hydrogel microspheres promote the regeneration of the nucleus pulposus by inhibiting acid-sensitive complexes显示文摘Intervertebral disc degeneration(IVDD)is commonly caused by imbalanced oxygen metabolism-triggered inflammation.Overcoming the shortcomings of antioxidants in IVDD treatment,including instability and the lack of targeting,remains challenging.Microfluidic and surface modification technologies were combined to graft chitosan nanoparticles encapsulated with strong reductive black phosphorus quantum dots(BPQDs)onto GelMA microspheres via amide bonds to construct oxygen metabolism-balanced engineered hydrogel microspheres(GM@CS-BP),which attenuate extracellular acidosis in nucleus pulposus(NP),block the inflammatory cascade,reduce matrix metalloproteinase expression(MMP),and remodel the extracellular matrix(ECM)in intervertebral discs(IVDs).The GM@CS-BP microspheres reduce H_(2)O_(2) intensity by 229%.Chemical grafting and electrostatic attraction increase the encapsulation rate of BPQDs by 167%and maintain stable release for 21 days,demonstrating the antioxidant properties and sustained modulation of the BPQDs.After the GM@CS-BP treatment,western blotting revealed decreased acid-sensitive ion channel-3 and inflammatory factors.Histological staining in an 8-week IVDD model confirmed the regeneration of NP.GM@CS-BP microspheres therefore maintain a balance between ECM synthesis and degradation by regulating the positive feedback between imbalanced oxygen metabolism in IVDs and inflammation.This study provides an in-depth interpretation of the mechanisms underlying the antioxidation of BPQDs and a new approach for IVDD treatment. | Ziang Li Feng Cai Jincheng Tang Yichang Xu Kaijin Guo Zonghan Xu Yu Feng Kun Xi Yong Gu Liang Chen | 2023 | Bioactive Materials2023，，6： | 0 |
| 8 | Capture efficiency and bias from the defect dynamics near grain boundaries in BCC Fe using mesoscale simulations显示文摘The capture efficiency describes the capability of a sink,such as a grain boundary(GB),dislocation,and void,to absorb point defects(PDs).The bias defines the difference in capture efficiency between the absorption of a vacancy and dumbbell at a sink.Complete kinetic information on PDs,including diffusion barriers and diffusion orientations,as well as accurate saddle points,are needed to determine the capture efficiency and bias at a sink accurately,which is computationally demanding.In the present study,the Self-Evolving Atomistic Kinetic Monte Carlo(SEAKMC)method was used to investigate the defect dynamics of PDs near different types of grain boundaries(GBs)(with both 100 and 110 families)accurately in body-centered cubic(BCC)iron(Fe).The capture efficiency,sink strength,and bias factor of different types of GBs were determined in Fe,which,different from traditional rate theory estimation,showed a distinct capture efficiency,sink strength,and bias in different GBs.The results demonstrate a strong positive correlation between the capture efficiency and the GB strain width,instead of the GB misorientation,GB energy,or GB-PD binding energy,which have been investigated previously.This work provides valuable insight into the radiation-induced microstructural evolution of GBs. | Jun Chai Shuo Jin Ziang Yu Haixuan Xu Guang-Hong Lu | 2021 | Journal of Materials Science & Technology2021，，34： | 0 |
| 9 | Kinematic and mixing characteristics of vortex interaction induced by a vortex generator model:a numerical study显示文摘The underlying effect of vortex interaction characterized by the merging and non-merging on mixing enhancement is of fundamental significance to understand the flow dynamics of strut injectors in scramjets.Starting from a simplified configuration of a vortex generator,this study focuses on the influence of geometric parameters on vortex structures and fluid mixing through compressible Navier-Stokes(NS)simulations.By adjusting the induction of outer vortices,the inner co-rotating vortex pair exhibits two modes of interaction(merging/separation regime)reflected by closer/farther vortex centers.Defined by the zero variation rate of the inner vortex spacing,the critical state of equilibrium is determined.The critical condition is well predicted by a theoretical model based on the Biot-Savart law.Through the introduction of mixedness and mixing time,the intrinsic impact of interaction modes on fluid mixing is revealed.Compared with the vortex dynamics in the merging regime,the one in the separation regime is more effective for passive scalar mixing augmentation.With efficient material stretching characterized by the higher interface stretching factor and averaging finite-time Lyapunov exponent(FTLE),the mixing time is shortened by as much as 2.5 times in the separation regime.The implication of the present two interaction regimes in mixing enhancement physically reflected by the averaging FTLE has the potential to improve the combustion performance and shorten the combustor chamber. | Ziang WANG Bin YU Bin ZHANG Miaosheng HE Hong LIU | 2021 | Applied Mathematics and Mechanics(English Edition)2021，42，3： | 0 |
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