检索结果-南通市图书馆

Microstructure and growth morphology of Frank-Kasper phase in rapidly solidified Mg_(32)Al_(17)Zn_(32) ternary alloys

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

Rare Metals 2009年第4期28卷 401-404页

作者： ZHU Man YANG Gencang WAN Diqing WANG zhijun zhou Yaohe State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 China

In the present investigation, the microstructures and growth morphology of Mg32（Al,Zn）49 Frank-Kasper phase in rapidly solidified Mg32Al17Zn32 temary alloys were studied in detail. The samples were characterised by X-ray diffraction analysis （XRD）, scanning electron microscopy （SEM）, field-emission scanning electron microscopy （FE-SEM） and energy dispersive spectrum （EDS）. The results show that the microstructures mainly consist of Mg3e（Al,Zn）49 Frank-Kasper phase and interdendritic Mg-rich O-phase. Under rapid solidification condition, Mg32（Al,Zn）49 Frank-Kasper phase reveals a perfect faceted dendritic characteristic in the shape of a three-fold symmetric microstructure with doublet tips in the axes direction. Observations for fracture surfaces show that the growth morphology of Mg32（Al,Zn）49 grains was truncated cubic, and its growth mechanism was also discussed.

关键词： Frank-Kasper phase rapid solidification faceted dendrite growth morphology

Optimal design of nanofiltration system for surface water treatment

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2016年第12期24卷 1674-1679页

作者： Fei Bi Haiyang Zhao zhijun zhou Lin Zhang Huanlin Chen Congjie Gao Key Laboratory of Biomass Chemical Engineering of MOE College of Chemical and Biological EngineeringZhejiang University Hangzhou 310027 China 96657 Unit of the Armed Forces Beijing 100011 China Ocean College Zhejiang University of Technology Hangzhou 310014 China

Both reverse osmosis(RO) and nanofiltration(NF) membranes have been increasingly used for water purification and desalination. However, the salt rejection of NF membranes is quite different from that of RO membranes,which makes a significant distinction in their process designs. This work started from the performance investigation of a single NF membrane element and then focused on the process design of the NF system for surface water treatment. In experimental tests, it was found that the observed rejection of the NF element becomes nearly constant when the concentrate flow is large enough, while the membrane flux of the NF element is quite stable regardless of the water flow across the membrane surface. These findings can be used to instruct the process design of the NF system for surface water treatment. In process design, a two-stage arrangement is sufficient for the NF system to reach the highest water recovery, while the RO system requires a three-stage arrangement.

关键词： Nanofiltration System design Salt rejection Surface water Recovery

Systematic method of applying ANN for chemical kinetics reduction in turbulent premixed combustion modeling

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2013年第4期58卷 486-492页

作者： zhou zhijun Lü Yu WANG ZhiHua XU YanWei zhou JunHu CEN KeFa State Key Laboratory of Clean Energy Utilization Department of Energy Engineering Zhejiang University

A novel method to apply artificial neural network (ANN) for both chemical kinetics reduction and source term evaluation is introduced and tested in direct numerical simulation (DNS) and large eddy simulation (LES) of reactive flows. To gather turbulence affected flame data for ANN training, a new computation-economical method, called 1D pseudo-velocity disturbed flame (PVDF), is developed and used to generate thermo-chemical states independent of the modeled flame. Then a back-propagation ANN is trained using scaled conjugate gradient algorithm to memorize the sample states with reduced orders. The new method is employed in DNS and LES modeling of H2 /air and C3H8 /air premixed flames experiencing various levels of turbulence. The test result shows that compared to traditional computation with full mechanism and direct integration, this method can obtain quite large speed-ups with adequate prediction accuracy.

关键词：人工神经网络预混火焰化学动力学燃烧模型湍流应用 LES模型系统

LES investigation of swirl intensity effect on unconfined turbulent swirling premixed flame

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2014年第33期59卷 4550-4558页

作者： Zhihua Wang Yanwei Xu Yu L zhijun zhou Junhu zhou Kefa Cen State Key Laboratory of Clean Energy Utilization Zhejiang University

A finite reaction rate model is presented as a closure of large eddy simulation(LES) to numerically study an open premixed methane/air swirling flame. The resultant model is firstly validated by comparing with reported data and then employed to investigate the effect of swirling intensity on flow field, flame characteristics and combustion instability of the swirling flame. Three different swirl numbers are considered. The LES results show that as swirling intensity increases, the vortex entrainment and micro-mixing are enhanced, leading to more lean equivalent ratios at flame front; consequently, higher swirling number causes lower flame temperatures and slower CO oxidization; for all simulated swirl numbers,flame fronts are completely located out of the recirculation zones and anchored at the inner surface of the annular swirling steams; swirl number has a crucial effect on swirling flame extension toward radial and tangential dimensions and then significantly affects streamwise flame length, which is a great influencing factor on combustion instability; vortex-induced disturbance on flame in streamwise plays a critical role in combustion instability.

关键词：预混火焰旋流强度 LES 漩涡燃烧不稳定性潜水大涡模拟速率模型

Synthesis, characterization and hydrotreating performance of supported tungsten phosphide catalysts

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2008年第2期2卷 155-164页

作者： Guida SUN Cuiqing LI zhijun zhou Fengyan LI Green Chemistry and New Catalytic Material Laboratory Beijing Institute of Petrochemical TechnologyBeijing 102617China

Supported tungsten phosphide catalysts were prepared by temperature-programmed reduction of their precursors(supported phospho-tungstate catalysts)in H2 and characterized by X-ray diffraction(XRD),BET,temperature-programmed desorption of ammonia(NH3-TPD)and X-ray photoelectron spectroscopy(XPS).The reduction-phosphiding processes of the precursors were investigated by thermogravimetry and differential thermal analysis(TG-DTA)and the suitable phosphiding temperatures were *** hydrodesulfurization(HDS)and hydrodenitrogenation(HDN)activities of the catalysts were tested by using thiophene,pyridine,dibenzothiophene,carbazole and diesel oil as the *** TiO2,c-Al_(2)O_(3) supports and the Ni,Co promoters could remarkably increase and stabilize active W species on the catalyst surface.A suitable amount of Ni(3%–5%),Co(5%–7%)and V(1%–3%)could increase dispersivity of the W species and the BET surface area of the WP/c-Al_(2)O_(3) *** WP/c-Al_(2)O_(3) catalyst possesses much higher thiophene HDS and carbazole HDN activities and the WP/TiO2 catalyst has much higher dibenzothiophene(DBT)HDS and pyridine HDN *** Ni,Co and V can obviously promote the HDS activity and inhibit the HDN activity of the WP/c-Al_(2)O_(3) *** G-Ni5 catalyst possesses a much higher diesel oil HDS activity than the sulphided industrial NiW/c-Al_(2)O_(3) *** general,a support or promoter in the WP/c-Al_(2)O_(3) catalyst which can increase the amount and dispersivity of the active W species can promote its HDS and HDN activities.

关键词： supported tungsten phosphide catalyst hydrodesulfurization(HDS) hydrodenitrogenation(HDN) dibenzothiophene carbazole

Yearly variation in character istics and health risk of polycyclic aromatic hydrocarbons and nitro-PAHs in urban shanghai from 2010-2018

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 2021年第1期33卷 72-79页

作者： Lu Yang Xuan Zhang Wanli Xing Quanyu zhou Lulu Zhang Qing Wu zhijun zhou Renjie Chen Akira Toriba Kazuichi Hayakawa Ning Tang Graduate School of Medical Sciences Kanazawa UniversityKakuma-machiKanazawa920-1192Jjapan School of Public Health Fudan UniversityShanghai 200032China Institute of Medical Pharmaceutical and Health SciencesKanazawa UniversityKakuma-machiKanazawa920-1192Japan Institute of Nature and Environmental Technology Kanazawa UniversityKakuma-machi920-1192KanazawaJapan

This study encompassed the regular observation of nine polycyclic aromatic hydrocarbons(PAHs)and three nitro-PAHs(NPAHs)in particulate matter(PM)in Shanghai in summer and winter from 2010 to *** results showed that the mean concentrations of∑PAHs in summer decreased by 24.7%in 2013 and 18.1%in 2017 but increased by 10.2%in 2015 compared to the data in ***,the mean concentrations of∑PAHs in winter decreased by 39.7%from 2010(12.8±4.55 ng/m^3)to 2018(7.72±3.33 ng/m^3),and the mean concentrations of 1-nitropyrene in winter decreased by 79.0%from 2010(42.3±16.1 pg/m^3)to 2018(8.90±2.09 pg/m^3).Correlation analysis with meteorological conditions revealed that the PAH and NPAH concentrations were both influenced by ambient *** diagnostic ratios of PAHs and factor analysis showed that they were mainly affected by traffic emissions with some coal and/or biomass *** ratio of 2-nitrofluoranthene to 2-nitropyrene was near 10,which indicated that the OH radical-initiated reaction was the main pathway leading to their secondary ***,backward trajectories revealed different air mass routes in each sampling period,indicating a high possibility of source effects from the northern area in winter in addition to local and surrounding ***,the mean total benzo[a]pyrene-equivalent concentrations in Shanghai in winter decreased by 50.8%from 2010(1860±645 pg/m^3)to 2018(916±363 pg/m^3).These results indicated the positive effects of the various policies and regulations issued by Chinese authorities.

关键词： Air pollution Fine particulate matter Polycyclic aromatic hydrocarbons Nitropolycyclic aromatic hydrocarbons Health risk Shanghai

Systematic and long-term technical validity of toxicity determination and early warning of heavy metal pollution based on an automatic water-toxicity-determination-system

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2024年第8期18卷 59-71页

作者： Yue Yi Baoguo Wang Xuemei Yi Fan Zha Haisen Lin zhijun zhou Yanhong Ge Hong Liu School of Life Science Beijing Institute of TechnologyBeijing 100081China Institute of Environmental Biology and Life Support Technology School of Biological Science and Medical EngineeringBeihang UniversityBeijing 100191China Infore Environment Technology Group Foshan 528000China Jiangmen Ecological Environment Monitoring Station Jiangmen 529000China Guangzhou Sub-branch of Guangdong Ecological and Environmental Monitoring Center Guangzhou 510000China

Water toxicity determination with electrochemically active bacteria(EAB)shows promise for providing early warnings for heavy metal pollution in ***,thus far,only idealized tests with a few types of heavy metals have been *** this study,an automatic water-toxicitydetermination system with high technical maturity was established,and the toxicological properties of common heavy metals were systematically *** results demonstrated that the common heavy metals linearly inhibited EAB currents in the range of 0.1 mg/L to 0.5 mg/*** toxicity ranking of the tested heavy metals was Pb^(2+)>Tl^(3+)>Cu^(2+)>Cd^(2+)>Zn^(2+)>Ni^(2+)>Hg^(2+)>As^(3+).The toxicity interaction mainly exhibited an antagonistic effect in binary heavy metal *** system can accurately determine surface water toxicity and rapidly monitor heavy metal pollution,with good repeatability and a long ***,this study demonstrates that EAB are capable of long-term(>60 d)surface water quality monitoring and on-site early warning of heavy metal pollution.

关键词： Biological early warning system Electrochemically active bacteria Water toxicity determination Biosensor Heavy metal pollution Early warning

Determination of large diameter bored pile's effective length based on Mindlin's solution

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 Traffic and Transportation Engineering(English Edition) 2015年第6期2卷 422-428页

作者： zhijun zhou Duanduan Wang Lipeng Zhang Weisi Ma School of Highway Chang'an University Department of Civil Engineering University of Illinois at Urbana-Champaign

The calculation equation of large diameter bored pile＇s effective length is connected with its distribution of pile shaft resistance. Thus, there is a great difference between the calculation results under the different distributions of pile shaft resistance. Primarily, this paper summarizes the conceptualized mode of pile shaft resistance under the circum- stance that the soil surrounding the piles presents different layer distributions. Secondly, based on Mindlin＇s displacement solution and in consideration of the effect of pile diam- eter, the calculation equation is optimized with the assumption that the pile shaft resis- tance has a parabolic distribution. The influencing factors are analyzed according to the calculation result of effective pile length. Finally, combined with an engineering example, the calculation equation deduced in this paper is analyzed and verified. The result shows that both the Poisson ratio of soil and pile diameter have impacted the effective pile length. Compared with the Poisson ratio of soil, the effect of pile diameter is more significant. If the pile diameter remains the same, the effect of the Poisson ratio of soil to the effective pile length decreases as the ratio of pile elastic modulus and soil share modulus increases. If the Poisson ratio of soil remains the same, the effect of the pile diameter to the effective pile length increases as the ratio of pile elastic modulus and soil share modulus increases. Thus the optimized calculation result of pile effective length under the consideration of pile diameter effect is more close to the actual situation of engineering and reasonably practicable.

关键词： Large diameter bored pile Pile shaft resistance Parabolic distribution Mindlin's solution Effect of pile diameter Effective pile length

Development of a Nickel-base Cast Superalloy with High Strength and Superior Creep Properties

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2005年第3期21卷 347-352页

作者： Jieshan HOU, Jianting GUO, Lanzhang zhou and zhijun LI Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Derived from Russian alloy CHS88U, six experimental Ni-base alloys named as A to F in the Ni-Cr-Co-W-Ti-Al-Hf system are designed, evaluated and processed. One of these alloys, F, shows excellent high temperature tensile strength and ductility with superior creep rupture properties. As predicted by using modeling tools such as PHACOM and NEW PHACOMP, there is hardly the tendency for formation of topologically close-packed phase (TCP) phase in alloy F. Furthermore, through microstructural observation, it is also found that no TCP phase is formed in alloy F after long-time exposure at high temperature. So alloy F has well balance of phase stability and mechanical properties in view of application for gas turbines. It is proved that d-electron approach can be applied for design and development of nickel-base superalloys for gas turbine application.

关键词： Conventional Ni-base superalloy Tensile strength Creep life PHACOMP