检索结果-南通市图书馆

NUMERICAL SIMULATION OF EFFECTS OF WALL THICKNESS AND CELL DENSITY ON THE THREE-WAY CATALYTIC CONVERTER PERFORMANCE

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 Mechanical Engineering 2005年第4期18卷 617-622页

作者： Wu Guojiang Tan song Huang zhen School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China

The transient symmetric mathematical model is established, and the effects of the wall thickness and cell density on the performance of a three-way catalytic converter are studied using numerical modeling. The conclusions show that the light-off time and the pressure drop through a converter are decreased, and the conversion efficiency during the warm-up period keeps almost invariant with reduction of the wall thickness of substrates, and that the pressure drop through a converter and a conversion efficiency during the warm-up state increases, and the light-off time almost keeps invariant when increasing cell density of substrates. Therefore, future catalytic converters should develop in the direction of thin wall thickness and high cell density substrates simultaneously.

关键词： Numerical simulations Advanced catalytic converter Emissions

Effect of high pressure on microstructure of cast Mg-8Zn-0.5Zr-0.5Gd alloy

在线全文

学校读者我要写书评

暂无评论

China Foundry 2017年第1期14卷 22-27页

作者： Dong-song Yin Yun-long Zhang Yong-liang An zhen-ling Wang Yun-zhou Hu ai-lian Liu College of Materials Science and Engineering Heilongjiang University of Science and TechnologyHarbin 150022China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China College of Materials Science&Engineering Jiamusi UniversityJiamusi 154007China

Mg-8Zn-0.5Zr-0.5Gd alloy was prepared by high pressure solidification. Effect of high pressure on microstructure, micro-hardness and corrosion behavior in Hank＇s solution of the Mg-8Zn-0.5Zr-0.5Gd alloy were investigated by means of optical microscopy （OM）, scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, and X-ray diffractometer （XRD）. The results showed that, compared with the conventional solidification, high pressure solidification obviously refined the grain size of Mg-8Zn-0.5Zr-0.5Gd alloy. The grain size was refined from 200-300 pm to 100-200 pm and the secondary dendrite arm spacing reduced from 30- 50 pm to 10-30 pro. Moreover, the solubility of Zn in the alloy increased and the amount and size of Mg-Zn-Gd phases significantly decreased. The micro-hardness of the alloy solidified under high pressure was improved significantly from 56.17 HV to 63.14 HV. The polarization resistance （Rp） of the alloy had a substantial increase in simulated body fluid, thus the corrosion rate was significantly reduced from 4.0 to 2.7 ***-1.

关键词： magnesium alloy high pressure solidification microstructure corrosion rate micro-hardness

Synthesis and characterization of amorphous Al-Mg-B prepared by various deposition temperatures

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2013年第2期32卷 159-164页

作者： Wen-Chao Qu ai-Min Wu Yi-zhen Bai Xin Jiang Key Laboratory of Materials Modification by Laser Ion and Electron BeamsMinistry of EducationDalian University of Technology School of Materials Science and Engineering Dalian University of Technology School of Physics and Optoelectronic Technology Dalian University of Technology Institute of Materials Engineering University of Siegen

Amorphous A1MgB thin films were synthesized via a combinatorial sputtering approach. The properties of aiMgB films with the varying deposition temperature was investigated. The deposition temperature was found to dominate the hardness of the amorphous asdeposited film. The hardness increases with increasing deposition tempera ture and may even exceed that of crystalline A1MgB14 mate rial. The high hardness may be attributed to the existence of randomly distributed B 12 icosahedra structure. Therefore, the thin film that was deposited on cemented carbide shows well cutting performances in turning Ti alloy bar. At the same time, an appropriate method of pretreatment is the key to ensure the coating tool with the excellent adhesion by impact fracture test.

关键词： Amorphous A1-Mg-B Depositiontemperature Properties Coated cutting tool

To form aiE product with the target analyte:a new strategy for excellent fluorescent probes,and convenient detection of hydrazine in seconds with test strips

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2017年第12期60卷 1596-1601页

作者： Yuchen song Luyi Zong Liyao Zhang zhen Li Department of Chemistry Wuhan UniversityWuhan 430074China College of Life Wuhan UniversityWuhan 430074China

A new hydrazine probe was designed, which demonstrates ultrafast "turn-on" response towards hydrazine both in solution and as gas, due to the excellent aiE(aggregation-induced emission) characteristic of the yielded products. Excitedly, the corresponding fabricated test strips can report the presence of trace hydrazine as low as 10 nmol/L in aqueous medium in seconds conveniently,with very high selectivity in the pH value ranging from 3.0 to 14.0.

关键词： hydrazine probe test strips aggregation-induced emission

C–F bond activation under transition-metal-free conditions

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2021年第10期64卷 1630-1659页

作者： Han-Jun ai Xingxing Ma Qiuling song Xiao-Feng Wu Leibniz-Institut fur Katalyse e.V.an der Universitat Rostock Rostock 18059Germany Dalian National Laboratory for Clean Energy Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Key Laboratory of Molecule Synthesis and Function Discovery Fujian Province UniversityCollege of ChemistryFuzhou UniversityFuzhou 350108China Institute of Next Generation Matter Transformation College of Material Sciences&EngineeringHuaqiao UniversityXiamen 361021China

The unique properties of fluorine-containing organic compounds make fluorine substitution attractive for the development of pharmaceuticals and various specialty materials,which have inspired the evolution of diverse C–F bond activation *** many advances have been made in functionalizations of activated C–F bonds utilizing transition metal complexes,there are fewer approaches available for nonactivated C–F bonds due to the difficulty in oxidative addition of transition metals to the inert C–F *** this regard,using Lewis acid to abstract the fluoride and light/radical initiator to generate the radical intermediate have emerged as powerful tools for activating those inert C–F ***,these transition-metal-free processes are greener,economical,and for the pharmaceutical industry,without heavy metal *** review provides an overview of recent C–F bond activations and functionalizations under transition-metal-free *** key mechanisms involved are demonstrated and discussed in ***,a brief discussion on the existing limitations of this field and our perspective are presented.

关键词： transition-metal-free fluorinated compounds C–F activation coupling

L log L criterion for a class of multitype superdiffusions with non-local branching mechanisms

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2019年第8期62卷 1439-1462页

作者： zhen-Qing Chen Yan-Xia Ren Renming song Department of Mathematics University of Washington Seattle WA 98195 USA LMAM School of Mathematical Sciences & Center for Statistical SciencePeking University Beijing 100871 China Department of Mathematics University of Illinois Urbana IL 61801 USA

In this paper, we provide a pathwise spine decomposition for multitype superdiffusions with nonlocal branching mechanisms under a martingale change of measure. As an application of this decomposition,we obtain a necessary and sufficient condition(called the L log L criterion) for the limit of the fundamental martingale to be non-degenerate. This result complements the related results obtained in Kyprianou et al.(2012),Kyprianou and Murillo-Salas(2013) and Liu et al.(2009) for superprocesses with purely local branching mechanisms and in Kyprianou and Palau(2018) for super Markov chains.

关键词： multitype superdiffusion non-local branching mechanism switched diffusion spine decomposition martingale

Effect of proximal contact strength on the three-dimensional displacements of implant-supported cantilever fixed partial dentures under axial loading

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2013年第6期14卷 526-532页

作者： zhen-zhen PENG Xin-min CHEN Jun WANG ai-jie LI Zu-jie XU State Key Laboratory of Oral Diseases West China Hospital of StomatologySichuan University

Objective:This study investigated the effect of proximal contact strength on the three-dimensional displacements of cantilever fixed partial denture(CFPD) under vertically concentrated loading with digital laser speckle(DLS) ***:Fresh mandible of beagle dog was used to establish the implant-supported CFPD for *** technique was employed for measuring the three-dimensional displacement of the prosthesis under vertically concentrated loading ranging from 200 to 3 000 *** effect of the contact tightness on the displacement of CFPD was investigated by means of changing the contact ***:When an axial concentrated loading was exerted on the pontic of the implant-supported CFPD,the displacement of the CFPD was the *** displacement of the prosthesis decreased with the increase of contact *** the contact strength was 0,0.95,and 3.25 N,the displacement of the buccolingual direction was smaller than that of the mesiodistal direction but greater than that of the occlusogingival *** the force on the contact area was 6.50 N,the mesiodistal displacement of the prosthesis was the biggest while the buccolingual displacement was the ***:The implant supported CFPD is an effective therapy for fully or partially edentulous *** restoration of the contact area and the selection of the appropriate contact strength can reduce the displacement of the CFPD,and get a better stress *** most appropriate force value is 3.25 N in this study.

关键词： Cantilever fixed partial denture Digital laser speckle technique Contact strength Three-dimensional displacement

Probes of axial and nonaxial hexadecapole deformation effects in nuclei around^(230)U

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第2期75卷 133-143页

作者： Zhuo song Hua-Lei Wang zhen-zhen Zhang Min-Liang Liu School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China Key Laboratory of High Precision Nuclear Spectroscopy Institute of Modern PhysicsChinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China

The structure properties for even–even nuclei around^(230)U,located on the hexadecapoledeformation island,are investigated using the potential-energy-surface calculation within the framework of the macroscopic-microscopic *** impact of different deformation degrees of freedom(including axial and nonaxial quadrupole and hexadecapole deformations)on total energy,shell,and pairing contributions is analyzed,based on the projected energy maps and *** single-particle structure is presented and briefly *** a large extent,a much better agreement with experimental data and other theoretical results is obtained if the hexadecapole deformations,especially the axial one,are taken into *** results could provide useful insights into understanding the effects of different quadrupole and hexadecapole deformations.

关键词： hexadecapole deformation triaxial deformation even-even nuclei potential-energysurface calculation macroscopic−microscopic model

A Novel Synthesis of Dimethyl Malonate by Carbonylation of Methyl Chloroacetate Catalyzed by Cobalt Complex

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2001年第3期12卷 207-210页

作者： Wei Hong song Xuan zhen JIANG Department of Chemistry Zhejiang UniversityHangzhou 310027

A novel method of preparing dimethyl malonate by carbonylation of methyl chloroacetate catalyzed by Na[Co(CO)(4)] was proposed. Na[Co(CO)(4)] was synthesized in situ in the presence of Na2S2O3 and iron powder. The effects of some reaction parameters such as temperature. CO pressure and the concentrations of catalyst on the yields of dimethyl malonate were discussed. The kinetic data were studied and a possible reaction mechanism was proposed.

关键词： Dimethyl malonate cobalt complex carbonylation reaction mechanism