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| 1 | Chatter stability and precision during high-speed ultrasonic vibration cutting of a thin-walled titanium cylinder显示文摘Titanium alloys are widely used in the aviation and aerospace industries due to their unique mechanical and physical properties.Specifically,thin-walled titanium(Ti)cylinders have received increasing attention for their applications as rocket engine casings,aircraft landing gear,and aero-engine hollow shaft due to their observed improvement in the thrust-to-weight ratio.However,the conventional cutting(CC)process is not appropriate for thin-walled Ti cylinders due to its low thermal conductivity,high strength,and low stiffness.Instead,high-speed ultrasonic vibration cutting(HUVC)assisted processing has recently proved highly effective for Ti-alloy machining.In this study,HUVC technology is employed to perform external turning of a thinwalled Ti cylinder,which represents a new application of HUVC.First,the kinematics,tool path,and dynamic cutting thickness of HUVC are evaluated.Second,the phenomenon of mode-coupling chatter is analyzed to determine the effects and mechanism of HUVC by establishing a critical cutting thickness model.HUVC can increase the critical cutting thickness and effectively reduce the average cutting force,thus reducing the energy intake of the system.Finally,comparison experiments are conducted between HUVC and CC processes.The results indicate that the diameter error rate is 10%or less for HUVC and 51%for the CC method due to a 40%reduction in the cutting force.In addition,higher machining precision and better surface roughness are achieved during thin-walled Ti cylinder manufacturing using HUVC. | Zhenlong PENG Deyuan ZHANG Xiangyu ZHANG | 2020 | Chinese Journal of Aeronautics2020，33，12： | 6 |
| 2 | Comparison of the Macrozoobenthic Community and Sedimentary Environment with and Without Horseshoe Crab Presence in the Crocodile Island Intertidal Zone,Xiamen,China显示文摘In order to compare the macrozoobenthic community and sedimentary environment with and without the presence of horseshoe crabs,the benthic macrofauna,sediment grain size,chromium(Cr),cobalt(Co),nickel(Ni),polycyclic aromatic hydrocarbon(PAHs),organic carbon and nitrogen were seasonally investigated at site A(with horseshoe crab presence),sites B and C(without horseshoe crab presence)in the Crocodile Island intertidal zone in Xiamen from June 2018 to July 2019.The results showed that most of the community parameters of benthic macrofauna,population parameters of common benthic macrofauna and environmental parameters were significantly different at the sites with horseshoe crab versus non-horseshoe crab sites.A two-way ANOVA test showed that the densities of Ceratonereis erythraeensis and Sigambra hanaokai had significant site variation.Cluster and nonmetric multi-dimensional scaling(NMDS)analysis showed the community composition of benthic macrofauna was significantly different among the three sampling sites over four seasons.The mean sand content at site A(64.32%)was higher than those at site B(36.01%)and site C(18.86%).Conversely,the mean contents of silt,clay,Cr,Co,Ni,organic carbon,organic nitrogen,phenanthrene,and pyrene at site A were lower than those at site B and site C.These observations are consistent with the expected preferences of horseshoe crabs to live in areas with 60%sand content,which is associated with abundant and edible clamworms in the Crocodile Island intertidal zone,Xiamen. | CAI Lizhe ZHAO Xiaoyu PENG Wenqing LIN Jingxiang YANG Deyuan RAO Yiyong FU Sujing CHEN Xinwei CAO Wenzhi | 2022 | Journal of Ocean University of China2022，21，3： | 1 |
| 3 | Dynamic Changes of Tobacco-growing Soil Nutrients and Enzymes After Application of Amelioration Materials显示文摘[Objectives]This study was conducted to clarify the improvement effects of different soil amelioration materials such as lime,green manure and bio-organic fertilizer on acidic tobacco-planting soil.[Methods]The dynamic changes of soil pH,soil nutrients and enzyme activity were studied by applying lime,lime+green fertilizer,and lime+green fertilizer+biological organic fertilizer.[Results]①After the application of amelioration materials,the soil pH and available phosphorus content of tobacco-growing soil showed a stepwise change of first increasing and then decreasing,and became stable at 60 d after tobacco transplanting;the soil organic matter,alkali-hydrolyzable nitrogen and available potassium content showed a gradual change trend of'high-low-high';and the soil invertase and urease activity showed a gradual change trend of'low-high-low'.②To 90 d after tobacco transplanting,the application of amelioration materials increased soil pH by 1.29-1.62 units,and increased organic matter content by 15.21%-20.86%,alkali-hydrolyzable nitrogen content by 6.83%-18.17%,available phosphorus content by 54.15%-217.85%,rapidly available potassium content by 11.42%-30.86%,soil invertase activity by 70.09%-18.93%,and soil urease activity by 64.07%-130.47%.③The combination of lime+green manure+alkaline microbial organic fertilizer had the best effect on the improvement of acidic tobacco-growing soil,and the effect of lime+green manure+acid microbial organic fertilizer on acidic soil was the second.[Conclusions]When applying lime,green fertilizer and alkaline bio-organic fertilizer should be applied to achieve sustainable improvement of strongly acidic soil. | Zhanghong CAO Gexuan SU Yongjun LIU Shuguang PENG Yongsheng DENG Jin CHEN Deyuan PENG Zhenghua WANG Jingjing WU Qianping YAN Xiaohua DENG | 2020 | Agricultural Biotechnology2020，9，4： | 1 |
| 4 | Enhanced flow sensing with interfacial microstructures显示文摘Biological flow receptors show astonishing performance and are used as models for the design of novel flow sensors.However,the functional importance of interfacial microstructures is seldom discussed in previous review papers.Herein,this review summarises the underlying biomechanical principles in the biological flow receptors and describes the recent progress in bio-inspired flow sensors,in which the underlying sensing-enhancement mechanisms are emphasised. | Yonggang Jiang Peng Zhao Zhiqiang Ma Dawei Shen Gongchao Liu Deyuan Zhang | 2020 | Biosurface and Biotribology2020，6，1： | 0 |
| 5 | Jackknife empirical likelihood test for the equality of degrees of freedom in t-copulas显示文摘It has been argued that fitting a t-copula to financial data is superior to a normal copula. To overcome the shortcoming that a t-copula only has one parameter for the degrees of freedom, the t-copula with multiple parameters of degrees of freedom has been proposed in the literature, which generalizes both the t-copulas and the grouped t-copulas. Like the inference for a t-copula, a computationally efficient inference procedure is to first estimate the correlation matrix via Kendall's τ and then to estimate the parameters of degrees of freedom via pseudo maximum likelihood estimation. This paper proposes a jackknife empirical likelihood test for testing the equality of some parameters of degrees of freedom based on this two-step inference procedure, and shows that the Wilks theorem holds. | Yanxi Hou Deyuan Li Aiai Liu Liang Peng | 2020 | Science China Mathematics2020，63，4： | 0 |
| 6 | Bio-inspired Flexible Airflow Sensor with Self-bended 3D Hair-like Configurations显示文摘This paper presents a novel flexible airflow sensor based on four curved microcantilevers arranged in a cross-form configuration.A self-bending method based on MEMS technology has been used to fabricate the curved microcantilevers structure,and this method can transfer a 2D plane structure into a 3D structure with good consistency in the morphology.The curved microcantilever consists of a polyimide(PI)top layer,silicon(Si)bottom layer,and platinum(Pt)piezoresistor at the root of the cantilever.The difference in the in-plane residual stress between the PI and Si layers bent the microcantilever upward.The curved-up microcantilever transfers the fluidic momentum that acts on it to drag force,which deflects the curved-up microcantilever and changes the resistance of the piezoresistor.To realize temperature compensation and decrease the noise,a reference resistor and an ambient temperature detector were integrated for the Wheatstone half-bridge measurement and temperature monitoring,respectively.The cross-form configuration of the curved-up cantilevers has high sensitivity advantages and possesses direction-sensing ability.Experimental results show that the sensitivity of the sensors increased as a function of the airflow velocity,and the sensors exhibited a maximum resolution of 4 mm⋅s^(−1) and a maximum sensitivity of 60.35 mV⋅(ms^(−1))^(−1) when the airflow velocity was larger than 38.5 m⋅s^(−1). | Dawei Shen Yonggang Jiang Zhiqiang Ma Peng Zhao Zheng Gong Zihao Dong Deyuan Zhang | 2022 | Journal of Bionic Engineering2022，19，1： | 0 |
| 7 | Dominance-caused differences in transpiration of trees in a Karst broadleaved mixed forest显示文摘Estimating stand transpiration of natural forests using traditional methods through up-scaling of sap fl ux density from sample trees based on stand sapwood area only is diffi cult because of the complexity of species,ages,and hierarchical structure of natural forests.To improve stand transpiration estimation,we developed an up-scaling method by considering the tree dominance eff ect based on the assumption that individual tree transpiration is aff ected by crown dominance and species,in addition to factors previously considered such as meteorological conditions,sapwood area,and soil moisture.In this study,the meteorological factors,soil moisture,and sap fl ux density of 15 sample trees of diff erent species and dominance in a natural evergreen and deciduous broadleaved mixed forest were simultaneously monitored from March 2012 to February 2014 in the Karst mountain region in southwestern China.After establishing a single tree transpiration model which considers the eff ects of dominance and species,an up-scaling method was explored to estimate stand transpiration.The results show that the transpiration intensity increased exponentially with increasing tree dominance.The contribution to annual stand transpiration from a few dominant trees(5.4%of trees, 28.2% of basal area) was up to 65.0%. The correspondingcontribution was 16.2% from sub-dominant trees(7.6% of trees, 16.2% of basal area) and 22.8% from middleandlower-layer trees (87.0% of trees, 55.6% of basal area).The variation of individual tree transpiration was mainly(97.9%) explained by tree dominance, but very weakly bytree species. The estimated annual stand transpiration was300.2 mm when using the newly developed method whichconsiders tree dominance, 52.5 mm (14.9%) lower than theestimation (352.7 mm) of traditional method which considersonly the sapwood area eff ect, and 8.5 mm (2.7%) lowerthan the estimation (308.6 mm) which considers the eff ectsof both species composition and sapwood area. The maintree characteristics aff ecting stand transpiration are tree size(sapwood area) and dominance. Consideration of tree dominancewill signifi cantly improve stand transpiration estimationand provide a more solid basis for guiding integratedforest-water management at stand scale. | Yanhui Liu Fangjun Ding Deyuan Shu Wenjun Zhao Yingchun Chui Yiju Hou Peng Wu | 2020 | Journal of Forestry Research2020，31，6： | 0 |
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