检索结果-南通市图书馆

Passage shock wave/boundary layer interaction control for transonic compressors using bumps

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 Aeronautics 2022年第2期35卷 82-97页

作者： Yongzhen LIU wei ZHAO Qingjun ZHAO qiang ZHOU Jianzhong XU Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100049China Innovation Academy for Light-duty Gas Turbine Chinese Academy of SciencesBeijing 100190China

Flow separation due to shock wave/boundary layer interaction is dominated in blade passage with supersonic relative incoming flow,which always accompanies aerodynamic performance penalties.A loss reduction method for smearing the passage shock foot via Shock Control Bump(SCB)located on transonic compressor rotor blade suction side is implemented to shrink the region of boundary layer *** curved windward section of SCB with constant adverse pressure gradient is constructed ahead of passage shock-impingement point at design rotor speed of Rotor 37 to get the improved *** investigations on both two models have been conducted employing Reynolds-Averaged Navier-Stokes(RANS)method to reveal flow physics of *** and analyses on simulation results have also been carried out,showing that passage shock foot of baseline is replaced with a family of compression waves and a weaker shock foot for moderate adverse pressure gradient as well as suppression of boundary layer separations and secondary flow of low-momentum fluid within boundary *** is found that adiabatic efficiency and total pressure ratio of improved blade exceeds those of baseline at 95%-100%design rotor speed,and then slightly worsens with decrease of rotatory speed till both equal below 60%rated *** investigated conclusion implies a potential promise for future practical applications of SCB in both transonic and supersonic compressors.

关键词： Flow separation Passage shock Shock Control Bump(SCB) Shock wave/boundary layer interaction Transonic compressors

Structure-Property Relationship Analysis of D-Penicillamine-Derivedβ-Polythioesters with Varied Alkyl Side Groups

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2023年第10期41卷 1555-1562页

作者： Chun-Yan Lyu wei Xiong Er-qiang Chen Hua Lu Beijing National Laboratory for Molecular Sciences Center for Soft Matter Science and EngineeringKey Laboratory of Polymer Chemistry and Physics of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China

The ring-opening polymerization of heterocyclic monomers and the reversed ring-closing depolymerization of corresponding polymers with neutral thermodynamics are broadly explored to establish a circular economy of next-generation ***(PTEs),analogues of polyesters,are emerging materials for this purpose due to their high refractive index,high crystallinity,dynamic property and *** this work,we synthesize and polymerize a series of D-penicillamine-derivedβ-thiolactones(NRPenTL)with varied side chain alkyl groups,and study the structure-property relationship of the resulting *** obtained PTEs exhibit tunable glass transition temperature in a wide range of 130–50℃,and melting temperature of 90–105℃.In addition,copolymerizations of monomers with different side chains are effective in modulating material *** obtained homo and copolymers can be fully depolymerized to recycle *** work provides a robust molecular platform and detailed structure-property relationship of PTEs with potential of achieving sustainable plastics.

关键词： β-Polythioesters Geminal dimethyl Structure-property relationship Chemical recycling to monomers

Effect of reduction pretreatment process on evolution of micro-porosity in 42CrMo billet

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2021年第4期28卷 413-423页

作者： Zhen Ning wei Yu Hong-qiang Liu Qing-wu Cai Collaborative Innovation Centre of Steel Technology University of Science and Technology BeijingBeijing 100083China HBIS Group Co. Ltd.Shijiazhuang 050000HebeiChina

Reduction pretreatment(RP)process,which is implemented after the billet is completely solidified,is an alternative process to further improve billet *** element method and experiment were used to investigate the effect of the RP process on the internal quality of 42CrMo *** ultrasonic testing technology was used to study the influence of the RP process on the *** a three-dimensional finite element model,the mechanism of the RP process on the porosity closure was *** experimental results show that the RP process eliminates the macro-porosities of the billet *** number of micro-porosities in the billets is effectively reduced,and the increase in deformation contributes to the reduction in *** with isothermal rolling,the RP process leads to a larger equivalent strain and hydrostatic integration in the billet center because of the temperature gradient,and the effect of the temperature gradient is greater with the increase in *** closure effect of micro-porosity is related not only to the stress state,but also to the distribution of *** increase in three-dimensional compressive stress is beneficial to the porosity *** the micro-porosities distributed densely,excessive stress could induce micro-porosity coalescence,which has the risk of inducing cracks.

关键词： Reduction pretreatment Temperature gradient Large deformation Micro-porosity Ultrasonic testing

The dissemination of relevant information on wildlife utilization and its connection with the illegal trade in wildlife

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 Forestry Research 2022年第1期33卷 357-367页

作者： Zhifan Song qiang Wang Zhen Miao wei Zhang Xuehong Zhou College of Wildlife and Protected Area Northeast Forestry UniversityHarbin 150040People’s Republic of China Key Laboratory of Wetland Ecology and Environment Northeast Institute of Geography and AgroecologyChinese Academy of SciencesChangchun 130102People’s Republic of China

We analyzed the generation and dissemination of relevant information on wildlife utilization based on the African bush elephant(Loxodonta africana Blumenbach.),the tiger(Panthera tigris L.)and the totoaba,a species of marine fish,(Totoaba macdonaldi Gilbert)as examples,whose populations are more threatened by the illegal wildlife *** compared the illegal trade in wildlife with related information in order to find possible associations,searched for relevant information on major international websites to summarize similarities in information production and dissemination,and used a"Zhiwei"dissemination analysis platform to analyze the dissemination of information circulated at *** results show that the most infuential information related to the trade in wildlife is mainly generated from news media websites and new selfmedia platforms,usually from non-governmental organizations concerned with wildlife *** main factors that affect the depth and breadth of disseminating relevant information on wildlife utilization include the participation of relatively infuential opinion leaders,the verification ratio of forwarding users,the number of followers,and affective *** information can stimulate and promote poaching and smuggling,regardless of their real market demand or their ***,all links in the course of information dissemination should be carefully examined in order to purify the information environment and reduce adverse effects of misleading information on wildlife protection.

关键词： Wildlife Illegal trade Misleading information Dissemination

Recent progress on multifunctional electromagnetic interference shielding polymer composites

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第3期134卷 106-131页

作者： Ke Tian Danrong Hu Quan wei qiang Fu Hua Deng College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China Rehabilitation Medicine Center and Institute of Rehabilitation Medicine Key Laboratory of Rehabilitation Medicine in Sichuan ProvinceWest China HospitalSichuan UniversityChengdu 610041China

The explosive development of electronic devices and wireless communication technology gives rise to the issue of electromagnetic pollution,known as electromagnetic interference(EMI).The accumulation of undesirable electromagnetic radiation in space disturbs the normal function of unshielded electronic appliances and poses seriously threat to human ***,the development of EMI shielding materials have emerged to solve the grim *** the complex application contexts,EMI shielding materials have evolved from traditional single-function to multi-functions to meet the ever-increasing application requirements in recent few *** paper provides detailed insight into the current re-search status and future challenges in the advancement of polymer-based EMI shielding materials with various ***,the basic theory of EMI shielding,factors influencing results and the dominating characterization technologies for EMI shielding properties are ***,the comprehensive descriptions of the seven types of multifunctional EMI shields are provided with respect to their structures,fabrication methods and specific ***,the corresponding critical scientific and technical issues are *** on our comprehensive analysis,the main challenges in the development of multifunctional EMI shielding materials are *** review aims to provide some guidance and inspire more efforts toward functional EMI shielding material research to satisfy the growing requirements for next-generation electronic systems.

关键词： Polymer-based composites Electromagnetic interference shielding Multiple losses Multifunctionality

A Critical Review of Real Gas Effects on the Regenerative Refrigerators

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 Thermal Science 2021年第3期30卷 782-806页

作者： CAO qiang LUAN Mingkai LI Peng wei Li WU Yan Institute of Refrigeration and Cryogenics School of Mechanical EngineeringTongji UniversityShanghai 201804China Shanghai Key Laboratory of Vehicle Aerodynamics and Vehicle Thermal Management Systems Tongji UniversityShanghai 201804China Department of Electrical Engineering School of Electronics and Information EngineeringTongji UniversityShanghai 201804China

The regenerative refrigeration is an important reverse work-heat conversion cycle with a theoretical coefficient of performance(COP)identical to the Carnot *** regenerative refrigerators are capable of working down to 4 K and largely fulfill the refrigeration requirement of modern technologies in many fields,especially for space ***,the enthalpy flow associated with the pressure dependence,abbreviated as pressure-induced enthalpy flow,brought about by real gas effects degrades the theoretical COP of the refrigerator to below about 30% of the Carnot efficiency at the temperatures of below the critical *** paper reviews the long history of exploring the real gas effects which dates back to the 1970 s and continues to *** explorations of uncovering the loss mechanism and reducing such losses are *** theories that are in accordance with experimental results and simulation results are *** further carry out analyses on the expansion components,including the pulse tube and the clearance *** inferences are made in order to explore the long-lasting puzzles about real gas *** is emphasized that the underlying cause of the loss in the regenerator is an indirect effect of the real gas *** study about carrying out a direct verification of the theory is proposed.

关键词： real gas effects regenerative refrigerators loss mechanism reduction methods

Characteristics of Welding Crack Defects and Failure Mode in Resistance Spot Welding of DP780 Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2016年第10期23卷 1104-1110页

作者： Xiao-pei WANG Yong-qiang ZHANG Jian-bin JU Jian-qiang ZHANG Jian-wei YANG Shougang Research Institute of Technology Beijing 100043 China College of Science China University of Petroleum (Beijing) Beijing 102249 China

The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested,and three different types of welding cracks in welded joints were investigated by optical microscopy,scanning electron microscopy and electron back-scattered ***,the failure mode of the welded joints in shear tensile test was *** is found the shear tensile strength of welded joints can be greatly improved by adding preheating current or tempering *** surface crack in welded joint is intergranular fracture,while the inner crack in welded joint is transgranular fracture,and the surface crack on the edge of the electrode imprint can be improved by adding preheating current or tempering *** traditional failure mode criterion advised by American Welding Society is no longer suitable for DP780 spot welds and the critical nugget size suggested by Pouranvari is overestimated.

关键词： resistance spot welding mechanical property crack defect failure mode DP780 steel

Dynamic Crosslinked Phosphorescent Poly(vinyl alcohol)-Terpyridine Films with Enhanced Mechanical Properties and Tunable Shape Memory

在线全文

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 1595-1601,I0015页

作者： Meng wei wei-Hao Feng Chen Yu Zhen-Yi Jiang Guang-qiang Yin wei Lu Tao Chen Key Laboratory of Advanced Marine Materials Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo315201China School of Chemical Sciences University of Chinese Academy of SciencesBeijing100049China School of Materials Science and Chemical Engineering Ningbo UniversityNingbo315211China

Achieving versatile room temperature phosphorescence(RTP)materials,especially with tunable mechanical properties and shape memory is attractive and essential but rarely ***,a strategy was reported to realize multi-functional RTP films with multicolor fluorescence,ultralong afterglow,adjustable mechanical properties,and shape memory through the synergistic dynamic interaction of lanthanide(Ln~Ⅲ)-terpyridine coordination,borate ester bonds,and hydrogen bondings in a poly(vinyl alcohol)(PVA)*** varying the amount of borax,the mechanical properties of the films could be finely controlled due to the change of crosslinking degree of dynamic borate ester bonds in *** assembly and disassembly of borate ester bonds upon the trigger of borax and acid were applied as reversible linkage to achieve programmable shape memory *** addition,the films displayed both fascinating multicolor fluorescence and ultralong afterglow characteristics due to the presence of Ln III doping and confinement of terpyridine in *** study provides a new avenue to impart modulable mechanical strength and shape memory to RTP materials.

关键词： Room temperature phosphorescence materials Dynamic bonds Multicolor fluorescent Tunable mechanical properties Shape memory

Comprehensive damage evaluation of localized spallation of thermal barrier coatings

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2017年第3期6卷 230-239页

作者： wei-wei ZHANG Guang-Rong LI qiang ZHANG Guan-Jun YANGa State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 ChinaInstitute of Publication Science Chang'an University Xi'an 710064 ChinaSchool of Materials Science and Engineering Chang'an University Xi'an 710064 China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 ChinaAECC Beijing Institute of Aeronautical Material Beijing 100095 China

Thermal barrier coatings (TBCs) enable the hot section part to work at high temperatures owing to their thermal barrier effect on the base metal components. However, localized spallation in the ceramic top-coat might occur after long duration of thermal exposure or thermal cycling. To comprehensively understand the damage of the top-coat on the overall hot section part, effects of diameter and tilt angle of the spallation on the temperature redistribution of the substrate and the top-coat were investigated. The results show that the spallation diameter and tilt angle both have a significant effect on the temperature redistribution of the top-coat and the substrate. In the case of the substrate, the maximum temperature increment is located at the spallation center. Meanwhile, the surface (depth) maximum temperature increment, having nothing to do with the tilt angle, increases with the increase of the spallation diameter. In contrast, in the case of the top-coat, the maximum temperature increment was located at the sharp corner of the spallation area, and the surface (depth) maximum temperature increment increases with the increase of both the spallation diameter and the tilt angle. Based on the temperature redistribution of the substrate and the top-coat affected by the partial spallation, it is possible to evaluate the damage effect of spalled areas on the thermal capability of TBCs.

关键词： thermal barrier coatings (TBCs) thermal property localized spallation damage evaluation