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Evolution of convex structure during counter-rotating electrochemical machining based on kinematic modeling

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Chinese Journal of Aeronautics 2021年第3期34卷 39-49页

作者： Wenjian CAO Dengyong WANG zhiyuan ren Di ZHU College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing 210016China

Counter-rotating electrochemical machining(CRECM)is a novel electrochemical machining(ECM)method,which can be used to machine convex structures with complex shapes on the outer surface of *** this study,the evolution of the convex structure during CRECM is *** complex motion form of CRECM is replaced by an equivalent kinematic model,in which the movement of the cathode tool is realized by matrix *** trajectory of the cathode tool center satisfies the Archimedes spiral equation,and the feed depth in adjacent cycles is a *** simulation results show that the variations of five quality indexes for the convex structure:as machining time increases,the height increases linearly,and the width reduces linearly,the fillets at the top and root fit the rational function,and the inclination angle of the convex satisfies the exponential *** current density distributions with different rotation angles is *** to the differential distribution of current density on workpiece surface,the convex is manufactured with the cathode window transferring into and out of the processing *** results agree very well with the simulation,which indicates that the proposed model is effective for prediction the evolution of the convex structure in CRECM.

关键词： Convex structure Counter-rotating electrochemical machining Current density Equivalent kinematic model Material removal

Optimizing the cleanliness in multi-segment disk amplifiers based on vector flow schemes

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High Power Laser Science and Engineering 2018年第1期6卷 1-6页

作者： zhiyuan ren Jianqiang Zhu Zhigang Liu Xiaowei Yang Key Laboratory on High Power Laser and Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800 China

The objective of maintaining the cleanliness of the multi-segment disk amplifier in Shenguang-II(SG-II) is to reduce laser-induced damage for optics. The flow field of clean gas, which is used for the transportation of contaminant particles,is a key factor affecting the cleanliness level in the multi-segment disk amplifier. We developed a gas–solid coupling and three-dimensional flow numerical simulation model. The three-dimensional and two-phase flow model is verified by the flow-field smog experiment and the particle concentration measurement experiment with the 130-disk amplifier in SG-II. By optimizing the boundary conditions with the same flow rate, the multi-inlet vector flow scheme can not only effectively reduce the purging time, but also prevent the reverse diffusion of contaminant particles in the multi-segment disk amplifier and the deposition of contaminant particles on the surface of the Nd:glass.

关键词： cleanliness computational fluid dynamics flow field multi-segment disk amplifier vector flow

Electrochemical behavior of Ti-6.5Al-2Zr-1Mo-1V alloy under rotating condition with periodically fluctuating current density

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Chinese Journal of Aeronautics 2022年第5期35卷 484-496页

作者： zhiyuan ren Dengyong WANG Juchen ZHANG Huayong LE Di ZHU College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing 210016China School of Mechanical Engineering Hefei University of TechnologyHefei 230009China

Titanium alloy plays a crucial role in the electrochemical field due to its excellent corrosion *** passivation and dissolution behaviors of Ti-6.5Al-2Zr-1Mo-1V(TA15)alloy in Na Cl solution were studied by simulating the electrochemical machining process in a rotating condition,which made the anode in a state with alternating high and low current *** probe micro analysis,ultra-depth microscope,scanning electron microscope,and X-ray photoelectron spectrometer were used to reveal the evolution of TA15 under fluctuating current *** existence state of the passivation film on TA15 surface was closely related to the pulse frequency of the periodically fluctuating current *** higher pulse frequency of 0.20 Hz,the material was hardly dissolved because passivation dominated the electrolysis behavior,while at lower pulse frequency of 0.01 Hz,the passivation and dissolution behaviors occurred alternately with the variation of the current ***,the thickness of the passivation film was inversely proportional to the applied current *** to the different electrochemical characteristics of a phase andβphase,the surface of the TA15 changed from being smooth to porous after a *** addition,the change of microstructure affected the content of O^(2–)and exposed the suboxides of *** a word,the change of pulse frequency and current density affected the electrochemical behavior of TA15,which was different from the conventional steady condition.

关键词： Dissolution Electrochemical behavior Passivation Rotating condition Ti-6.5Al-2Zr-1Mo-1V alloy

A high power efficiency method using orthogonal signal decomposition in high PAPR system

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Science China(Information Sciences) 2013年第4期56卷 173-179页

作者： ren zhiyuan LI YongZhao ZHANG HaiLin HAN Kun State Key Laboratory of Integrated Services Network Xidian University Xi'an Communication Institute

To solve the low-power-efficiency problem for high peak to average power ratio systems,such as OFDM,an orthogonal inhomogeneous signal decomposition approach is proposed in this *** novel method decomposes the signal into branch signals orthogonally,which can adapt to the change of saturate power of each branch power ***,the novel method has the advantages of both high power efficiency of power amplifier and low PAPR of branch ***,this is more suitable for practical *** simulation results indicate that the proposed method can increase the power efficiency remarkably without reducing the BER performance in the receiver.

关键词： green radio power amplifier orthogonal inhomogeneous signal decomposed power efficiency energy conservation

A Novel Load Balancing Strategy of Software-Defined Cloud/Fog Networking in the Internet of Vehicles

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China Communications 2016年第S2期13卷 140-149页

作者： Xiuli He zhiyuan ren Chenhua Shi Jian Fang The State Key Laboratory of ISN in School of Telecommunications Engineering No.2 South Taibai Road Yan Ta DistrictXidian University The State Radio Monitoring Center and Testing Center

The Internet of Vehicles(IoV)has been widely researched in recent years,and cloud computing has been one of the key technologies in the *** cloud computing provides high performance compute,storage and networking services,the IoV still suffers with high processing latency,less mobility support and location *** this paper,we integrate fog computing and software defined networking(SDN) to address those *** computing extends computing and storing to the edge of the network,which could decrease latency remarkably in addition to enable mobility support and location ***,SDN provides flexible centralized control and global knowledge to the *** order to apply the software defined cloud/fog networking(SDCFN) architecture in the IoV effectively,we propose a novel SDN-based modified constrained optimization particle swarm optimization(MPSO-CO) algorithm which uses the reverse of the flight of mutation particles and linear decrease inertia weight to enhance the performance of constrained optimization particle swarm optimization(PSO-CO).The simulation results indicate that the SDN-based MPSO-CO algorithm could effectively decrease the latency and improve the quality of service(QoS) in the SDCFN architecture.

关键词： internet of vehicles cloud computing cloud/fog network software defined networking load balancing

Hazard analysis of tsunami disaster on the Maritime Silk Road

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Acta Oceanologica Sinica 2020年第1期39卷 74-82页

作者： Jingming Hou Xiaojuan Li Peitao Wang Juncheng Wang zhiyuan ren National Marine Environmental Forecasting Center Beijing 100081China College of Resource Environment and Tourism Capital Normal UniversityBeijing 100048China Key Laboratory of Research on Marine Hazards Forecasting State Oceanic AdministrationBeijing 100081China

The Maritime Silk Road is not only a passageway for business and trade, but also the road of friendship between eastern and western civilizations. The Indian Ocean tsunami in 2004 caused major damage to several coastal countries. Tsunami occurrence regularity and hazard analysis are needed to ensure economic and cultural exchange on the Maritime Silk Road. To explore and identify tsunami hazard on the Maritime Silk Road, the spatial and temporal characteristics of historical tsunami events were given out. Some useful information hidden in historical tsunamis was searched from source parameters, such as seismic magnitude, focal depth and water depth. The tsunami possibility in the case of earthquake occurrence was also studied, exploring the probability of tsunami caused by different magnitudes. The analysis result shows that tsunamis on the Maritime Silk Road mainly occurred in 8 major tectonic faults, each of which has different tsunami occurrence regularity. On the basis of statistical analysis, a numerical model was used to simulate the potential tsunamis and show the tsunami hazard levels along the coast of Maritime Silk Road. The research results of this paper can help the tsunami early warning and ensure the safety of economic and cultural exchanges on the Maritime Silk Road.

关键词： tsunami occurrence regularity hazard Maritime Silk Road

Land Cover Changes and Drivers in the Water Source Area of the Middle Route of the South-to-North Water Diversion Project in China from 2000 to 2015

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Chinese Geographical Science 2020年第1期30卷 115-126页

作者： GAO Wenwen ZENG Yuan ZHAO Dan WU Bingfang ren zhiyuan State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijing 100101China Research Center for Policy and Technology of the Office of the South-to-North Water Diversion Project Ministry of Water ResourcesBeijing 100038China

The Middle Route of the South-to-North Water Diversion Project(MR-SNWDP)in China,with construction beginning in 2003,diverts water from Danjiangkou Reservoir to North China for residential,agriculture and industrial *** water source area of the MR-SNWDP is the region that is most sensitive to and most affected by the construction of this water diversion *** this study,we used Landsat Thematic Mapper(TM)and HJ-1 A/B images from 2000 to 2015 by an object-based approach with a hierarchical classification method for mapping land cover in the water source *** changes in land cover were illuminated by transfer matrixes,single dynamic degree,slope zones and fractional vegetation cover(FVC).The results indicated that the area of cropland decreased by 31%and was replaced mainly by shrub over the past 15 years,whereas forest and settlements showed continuous increases of 29.2% and 77.7%,*** changes in cropland were obvious in all slope zones and decreased most remarkably(–43.8%)in the slope zone above 25°.Compared to the FVC of forest and shrub,significant improvement was exhibited in the FVC of grassland,with a growth rate of 16.6%.We concluded that local policies,including economic development,water conservation and immigration resulting from the construction of the MR-SNWDP,were the main drivers of land cover changes;notably,they stimulated the substantial and rapid expansion of settlements,doubled the wetlands and drove the transformation from cropland to settlements in immigration areas.

关键词： remote sensing land cover change object-based classification Middle Route of the South-to-North Water Diversion Project(MR-SNWDP) China

J-comb: An image fusion algorithm to combine observations covering different spatial frequency ranges

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Science China(Physics,Mechanics & Astronomy) 2022年第9期65卷 138-156页

作者： Sihan Jiao Yuxin Lin Xiangyu Shui Jingwen Wu zhiyuan ren Di Li National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Centre for Astrochemical Studies Max-Planck-Institut f¨ur Extraterrestrische PhysikGarching 85748Germany Astrophysics Department Munich UniversityMunich 81679Germany NAOC-UKZN Computational Astrophysics Centre University of KwaZulu-NatalDurban 4000South Africa

Ground-based, high-resolution bolometric(sub)millimeter continuum mapping observations on spatially extended target sources are often subject to significant missing fluxes. This hampers accurate quantitative analyses. Missing flux can be recovered by fusing high-resolution images with observations that preserve extended structures. However, the commonly adopted image fusion approaches do not maintain the simplicity of the beam response function and do not try to elaborate the details of the yielded beam response functions. These make the comparison of the observations at multiple wavelengths not straightforward. We present a new algorithm, J-comb, which combines the high and low-resolution images linearly. By applying a taper function to the low-pass filtered image and combining it with a high-pass filtered image using proper weights, the beam response functions of our combined images are guaranteed to have near-Gaussian shapes. This makes it easy to convolve the observations at multiple wavelengths to share the same beam response functions. Moreover, we introduce a strategy to tackle the specific problem that the imaging at 850 μm from the present-date ground-based bolometric instrument and that taken with the Planck satellite do not overlap in the Fourier domain. We benchmarked our method against two other widely-used image combination algorithms, CASA-feather and MIRIAD-immerge, with mock observations of star-forming molecular clouds. We demonstrate that the performance of the J-comb algorithm is superior to those of the other two algorithms. We applied the J-comb algorithm to real observational data of the Orion A star-forming region. We successfully produced dust temperature and column density maps with ~10′′angular resolution, unveiling much greater details than the previous results. A py Thon code release of J-comb and implementation of the algorithm are available at https://***/Sihan Jiao/J-comb.

关键词： star formation molecular clouds image processing

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Characteristics of air pollution by polychlorinated dibenzo-p-dioxins and dibenzofurans in the typical industrial areas of Tangshan City,China

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Journal of Environmental Sciences 2011年第2期23卷 228-235页

作者： zhiyuan ren Bing Zhang Pu Lu Cheng Li Lirong Gao Minghui Zheng Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China.

The ambient air in vicinity of different industrial sources for PCDD/PCDFs was sampled by TSP/PM10 active samplers and passive PUF disk samplers in Tangshan City, a metropolis containing clusters of various industrial plants. The TEQ concentrations of PCDD/PCDFs ranged from 44.2 to 394.1 fg I-TEQ/m^3 with an average of 169.9 fg I-TEQ]m^3. 2,3,4,7,8-PeCDF was the dominant contributor to ∑TEQ, contributing 41% （12% to 55%）, while 1,2,3,4,6,7,8-HpCDE OCDD and OCDF were the major congeners for the total concentrations. The ratios of ∑PCDF/∑PCDD reached 2.54 on average, suggesting that de novo synthesis in thermal processes played an important role to the airborne pollution of PCDD/PCDFs. The similarities congener profiles indicated that TSP and PM10 active sampling methods are comparable for the determination of the PCDD/PCDFs in ambient air, and the ratios of concentrations determined by the two methods suggested that the PCDD/PCDFs tended to stay in fine particles. It was found that 2,3,7,8-TCDF and OCDD were the dominating congeners in the passive PUF disks samples. Through principal components analysis, the coke industry was suggested to be a relatively high potential emission source for PCDD/PCDFs in the ambient air of Tangshan, which was possibly formed by de novo synthesis mechanism. In this study, the atmospheric impacts to the environment from different industrial sources could be ranked as follows （from high to low）： coking, iron sintering, steel making, power generation and chlorinate alkali chemical production industries.

关键词： ambient air dioxins inhalable particles total suspended particles metropolis