检索结果-南通市图书馆

A Study on the Impact of Chemical Structure on the Evolution of Aggregate Structure in Fiber-shaped High Density Polyethylene Vitrimer

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第10期42卷 1557-1565,I0013页

作者： Bing Wang Yuan-chu gao Hai Wang Hui Niu State Key Laboratory of Fine Chemicals School of Chemical EngineeringDalian University of TechnologyDalian116024China

Vitrimers have emerged as a prominent research area in the field of polymer *** of the studies have focused on synthesizing polymers with versatile dynamic crosslinking structures,while the impact of chemical structure on aggregate structure of vitrimers,particularly during polymer processing,remains insufficiently *** present study employed commercial maleic anhydride-grafted-high density polyethylene(M-g-HDPE)as the matrix and hexanediol as the crosslinker to facilely obtain fiber-shaped HDPE vitrimers through a reaction extrusion and post-drawing *** chemical structure characterization,morphology observation,thermal and mechanical properties investigation,as well as aggregate structure analysis,this work revealed the influence of dynamic bonds on the formation of aggregate structures during fiber-shaped vitrimers processing.A small amount of dynamic bonds in HDPE restricts the motion of PE chain during melt-extruding and post-drawing,resulting in a lower orientation of the PE ***,lamellar growth and fibril formation during post-drawing at high temperature are enhanced to some extent due to the competition between dynamic bond and chain *** uneven morphology of fibershaped HDPE vitrimers can be attributed to the stronger elastic effect brought by dynamic bonding,which plays a more dominant role in determining the mechanical properties of fiber-shaped vitrimers compared to aggregate *** Vitrimers have emerged as a prominent research area in the field of polymer *** of the studies have focused on synthesizing polymers with versatile dynamic crosslinking structures,while the impact of chemical structure on aggregate structure of vitrimers,particularly during polymer processing,remains insufficiently *** present study employed commercial maleic anhydride-grafted-high density polyethylene(M-g-HDPE)as the matrix and hexanediol as the crosslinker to facilely obtain fiber-shap

关键词： High density polyethylene vitrimer Fiber-shaped Aggregate structures Transesterification reaction

Selective Laser Melting of In Situ TiB/Ti6Al4V Composites: Formability, Microstructure Evolution and Mechanical Performance

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第6期33卷 774-788页

作者： Yue Su Shun-Cun Luo Liang Meng Piao gao ze-Min Wang Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

In the present study, a series of in situ TiB/Ti6Al4V composites were fabricated using selective laser melting. The formability, microstructure evolution and mechanical properties of the as-built samples added with different contents of TiB2 were studied. It is found that the densification level is related to both the content of TiB2 and laser energy density. The added TiB2 reinforcement particle can spontaneously react with titanium and then form the TiB phase. The needle-like TiB phase tends to transform into dot-like particles with the decrease in energy density. Additionally, with the increase in TiB2 content, the TiB phase is coarsened due to the increased nucleation rate and more reactions. The grain morphology is found to largely depend on the translational speed of solid–fluid interface determined by the temperature gradient and cooling rate. Also, the microhardness of the as-built TiB/Ti6Al4V composites is obviously improved. More interestingly, as the energy density increases, the microhardness of the as-built TiB/Ti6Al4V composites firstly increases and then decreases due to the synergy of grain size and different morphologies and distribution of TiB phases. The wear resistance of TiB/Ti6Al4V composites is far superior to that of Ti6Al4V alloy owing to the increased microhardness resulted from the uniform distribution of the hard TiB phase in the matrix.

关键词： Selective laser melting TiB/Ti6Al4V composites Energy density Densification behavior Microhardness Wear resistance

Purification and characterization of Al_(13) species in coagulant polyaluminum chloride

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2009年第1期21卷 18-22页

作者： gao Baoyu chu Yongbao YUE Qinyan WANG Yan School of Environmental Science and Engineering Shondong University Jinan 250100 China. School of Environment and Safety Engineering Qingdong University of Science and Technology Qingdao 266042 China Key Laboratory of Colloid and Interface Chemistry Minstry of Education Shandong University Jinan 250100 China

Nano-Al13 was separated and purified by four methods to investigate its characteristic, and was analyzed by Al-Ferron timed complexation spectrophotometer, ^27Al-NMR （nuclear magnetic resonance）, and transmission electron microscopy （TEM）. Coagulation efficiency of nano-Al13, polyaluminum chloride （PAC）, and AlCl3 in synthetic water were also investigated by jar test. The dynamic process and aggregation state of kaolin suspensions coagulating with nano-Al13, PAC, and AlCl3 were also investigated. The experimental results indicated that the efficiency of gel column chromatography method was the highest for separating PAC solution with low Al concentration. Ethanol and acetone method was simple and could separated PAC solution with different Al concentrations, while silicon alkylation white block column chromatography method could separate PAC solution only with low Al concentration. The SO4^2-/Ba^2＋ displacement method could separate PAC solution with high Al concentration, but extra inorganic cation and anion could be introduced into the solution during the separation. The coagulation efficiency and dynamic experimental results showed that nano- Al13 with a high positive-charged species was the main species of electric neutralization in coagulation process, and it could reduce the turbidity and increase the effective particles collision rate efficiently in coagulation process. Its coagulation speed and the particle size of coagulant formed were of greatest value in this study.

关键词： nano-Al13 separation and purification coagulation dynamic processes

Effect of FeSi additive in dual-chamber sample cup on thermal analysis characteristic values and vermiculating rate of compacted graphite iron

在线全文

学校读者我要写书评

暂无评论

China Foundry 2024年第1期21卷 91-100页

作者： De-quan Shi ze-yu Liu Gui-li gao Yi-cheng Feng School of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China School of Materials Science and Chemical Engineering Harbin University of Science&TechnologyHarbin 150040China School of Mechanical and Energy Engineering Shanghai Technical Institute of Electronics and InformationShanghai 201411China

Thermal analysis plays a key role in the online inspection of molten iron *** solidification process of molten iron can be reflected by thermal analysis curves,and silicon is one of important elements affecting the solidification of molten *** this study,FeSi75 was added in one chamber of the dual-chamber sample cup,and the influences of FeSi75 additive on the characteristic values of thermal analysis curves and vermiculating rate were *** results show that with the increase of FeSi75,the start temperature of austenite formation TALfirstly decreases and then increases,but the start temperature of eutectic growth TSEF,the lowest eutectic temperature TEU,temperature at maximum eutectic reaction rate TEM,and highest eutectic temperature TERkeep always an *** temperature at final solidification point TEShas little *** FeSi75 additive has different influences on the vermiculating rate of molten iron with different vermiculation,and the vermiculating rate increases for lower vermiculation molten iron while decreases for higher *** to the thermal analysis curves obtained by a dual-chamber sample cup with 0.30wt.%FeSi75 additive in one chamber,the vermiculating rate of molten iron can be evaluated by comparing the characteristic values of these *** time differenceΔtERcorresponding to the highest eutectic temperature TERhas a closer relationship with the vermiculating rate,and a parabolic regression curve between the time differenceΔtERand vermiculating rateηhas been obtained within the range of 65%to 95%,which is suitable for the qualified melt.

关键词： FeSi75 additive characteristic value vermiculating rate thermal analysis compacted graphite iron

Geochronology, Geochemistry and Hf Isotope of the Late Mesozoic Granitoids from the Lushi Polymetal Mineralization Area: Implication for the Destruction of Southern North China Craton

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2020年第2期31卷 313-329页

作者： Yuanyuan Zhai Shuai gao Qingdong zeng Shaoxiong chu Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Institution of Earth Science Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences、Beijing 100049 China Linyi Natural Resources and Planning Bureau Linyi 276000China

The North China Craton(NCC)is the best example of an Archean craton that has lost its stability in the Late *** the cratonic destruction is generally considered to have occurred in the Eastern Block and reached a peak in the Early Cretaceous,the exact areal extent of cratonic destruction is debated,especially the southern and northern margin of the *** we report geochronology,geochemical and Hf isotopic data of the Late Mesozoic granitoids from Lushi polymetal mineralization area(LPMA)in the southern margin of *** results provide new insights into the destruction in the southern margin of the NCC during the Late *** U-Pb dating indicates that eight granitoids intruded in the Late Jurassic to Early Cretaceous(136.8–154.1 Ma),*** signatures define these granitoids being A-type or I-type granite that formed in an extension *** addition,Hf isotopic compositions of zircons from these granitoids vary in a relatively large range,withεHf(t)values and TDM2 ages ranginge from-26.1 to+15.2 and 215 to 2849 Ma,*** parental magmas were likely derived from diverse sources,including materials of the partial melting of ancient lower crust and mantle-derived mafic magmas in various *** with previous studies on the contemporaneous magma-tectonic activities in circum of NCC,we suggest that the rim of NCC was already unstabilized from the Late Jurassic in the *** subduction of the Paleo-Pacific Plate was the main trigger to the destruction of the southern margin of NCC,which was responsible for the lithospheric extension and thinning,extensive magmatism and mineralization.

关键词： Late Mesozoic granitoids geochronology geochemistry Hf isotopic composition southern margin of NCC cratonic destruction

Dynamic, thermal, and vibrational analysis of ball bearings with over-skidding behavior

在线全文

学校读者我要写书评

暂无评论

Friction 2023年第4期11卷 580-601页

作者： Shuai gao Qinkai HAN Paolo PENNACCHI Steven CHATTERTON Fulei chu Department of Mechanical Engineering Politecnico di MilanoVia G.La Masa 1Milan 20156Italy State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

The term“over-skidding”indicates that the cage rotational speed ratio exceeds the theoretical value as ball purely rolls on the *** from the skidding phenomenon that occurs in low-load and high-speed bearing,over-skidding usually occurs in large-size angular contact bearings,and it is still difficult to suppress under high load *** main forms of damage to the raceway by over-skidding are spinning and gyro *** further explore the vibration characteristics and thermal effects of this phenomenon,a set of over-skidding tests of an angular contact bearing with a bore diameter of 220 mm were conducted on an industrial-size test *** the experiment,the influence of axial load,rotational speed,and lubrication conditions on the occurrence of over-skidding were *** on a previous dynamics model,the heat generation and thermal network models were integrated in the present study to predict the over-skidding and its thermal *** model was validated in terms of the measured degree of over-skidding and temperature *** results showed that the degree of over-skidding reaches up to 12%of the theoretical value,and the friction power loss of the ball-pocket accounts for 30%of the total power *** analysis of the vibration signal showed a strong correlation between the bearing vibration characteristics and over-skidding behavior,thereby providing a way to indirectly measure the degree of over-skidding.

关键词： over-skidding vibration characteristics dynamic model power loss temperature rise

Ambient air temperature effects on the temperature of sewage sludge composting process

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2005年第6期17卷 1004-1007页

作者： HUANG Qi-fei CHEN Tong-bin gao Ding HUANG ze-chun Chinese Research Academy of Environmental Sciences Beijing 100012 China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

Using data obtained with a full-scale sewage sludge composting facility, this paper studied the effects of ambient air temperature on the composting temperature with varying volume ratios of sewage sludge and recycled compost to bulking agent. Two volume ratios were examined experimentally, 1 ： 0 ： 1 and 3 ： 1 ： 2. The results show that composting temperature was influenced by ambient air temperature and the influence was more significant when composting was in the temperature rising process： composting temperature changed 2.4-6.5℃ when ambient air temperature changed 13℃. On the other hand, the influence was not significant when composting was in the high-temperature and/or temperature falling process： composting temperature changed 0.75-1.3℃ when ambient air temperature changed 8-15℃. Hysteresis effect was observed in composting temperature＇s responses to ambient air temperature. When the ventilation capability of pile was excellent（at a volume ratio of 1：0：1）, the hysteresis time was short and ranging 1.1-1.2 h. On the contrary, when the proportion of added bulking agent was low, therefore less porosity in the substrate（at a volume ratio of 3：1：2）, the hysteresis time was IonQ and ranging 1.9-3.1 h.

关键词： sewage sludge composting ambient air temperature hysteresis

Torque allocation of four-wheel drive EVs considering tire slip energy

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2022年第2期65卷 61-74页

作者： Bingzhao gao Yongjun YAN Hong chu Hong CHEN Nan XU State Key Laboratory of Automotive Simulation and Control Jilin University Clear Energy Automotive Engineering Center Tongji University

With the increasing peak torque of the in-wheel motor, the tire slip energy dissipation becomes as considerable as the motor energy loss. The actuation redundancy in four-wheel drive electric vehicles has the innate advantage of reducing the energy dissipation of the tire slip according to different criteria. This study innovatively optimizes the energy loss of the motor and the slip energy consumption of the tire under a unified framework. A more accurate calculation model of the tire slip force and slip energy is adopted in the cost function. Its feasibility and potential are shown through simulation case studies based on different road adhesion coefficients among three allocation methods: considering both motor energy loss and tire slip loss, only considering the motor energy loss, and only considering the axis load distribution. The simulation results demonstrate that the torque allocation method considering both motor energy loss and tire slip loss can dramatically reduce the tire slip energy and tire wear with an acceptable motor energy efficiency sacrifice compared to the present allocation algorithms.

关键词： control allocation four-wheel drive electric vehicles tire slip energy model multi-objective optimization

同方期刊数据库

Effects of floral sexual investment and dichogamy on floral longevity

在线全文

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2015年第2期8卷 116-121页

作者： Jie gao Ying-ze Xiong Shuang-Quan Huang State Key Laboratory of Hybrid Rice College of Life SciencesWuhan UniversityNo.299 Bayi RoadWuchang DistrictWuhan 430072China School of Life Sciences Central China Normal University152 Luoyu AvenueHongshan DistrictWuhan 430079China

Aims Floral longevity,the duration that a flower remains open and func-tional,varies greatly among *** in floral longevity has been considered to be optimal strategy for resource allocation under different ecological conditions,mainly determined by the rates of pollination and cost of flower ***,it is unclear whether an intrinsic factor,floral sexual investment,con-strains evolution of floral *** theoretical model also pre-dicts that dichogamy favors long-lived flowers,but empirical studies to test this prediction remain *** To examine the effect of floral sexual investment on floral longevity,we measured flower size together with pollen and ovule production in 37 sympatric flowering plants in a natural *** duration of the female and male phase in 21 protandrous species and floral longevity of the other 16 adichogamous species were documented in the *** Findings Floral longevity varied from 1 day to 15 days,while pollen num-ber per flower varied from 643 to 710880 and ovule number per flower from 1 to 426 in the 37 *** size was corre-lated with pollen production as well as ovule *** longevity was positively related to pollen production but not to ovule *** with the prediction that dichogamy favors long-lived flowers,we found the floral longevity of pro-tandrous species was significantly longer than that of adichoga-mous *** the protandrous species,pollen production per flower was observed to be positively related to male duration,while ovule production was not related to female *** analyses of variation in floral longevity and sexual investment among different species suggest that the floral sexual investment could be an intrinsic factor contributing to the selected floral longevity,particularly the male phase,and that high pollen pro-duction could potentially increase pollen removal,*** pro-ductive success.

关键词： floral longevity female phase duration male phase duration flower size floral sexual investment dichogamy