期刊文献+
共找到44,594篇文章
< 1 2 250 >
每页显示 20 50 100
Effect of plastic strain and forming temperature on magnetic properties of low-carbon steel 预览
1
作者 Fan Zeng Xue-jiao Bai +2 位作者 Cheng-liang Hu Min-jun Tang Zhen Zhao 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2020年第2期210-219,共10页
Claw poles are a key component of automobile generators.The output power performance of the generator is very dependent on the magnetic properties of its claw poles.Plastic deformation is known to significantly change... Claw poles are a key component of automobile generators.The output power performance of the generator is very dependent on the magnetic properties of its claw poles.Plastic deformation is known to significantly change the magnetic behavior of ferromagnetic materials in claw poles.In this paper,changes in the magnetic properties of low-carbon steel,used for claw pole components due to their plastic deformation,were investigated for different strains and temperatures.Ring-shaped material samples were prepared by machining and their magnetic properties were measured.The surface roughness was first evaluated and a machining process with an arithmetic average of roughness Ra 1.6μm was selected as enabling the lowest measurement error.Hysteresis loops at different applied magnetic fields of the material were obtained for different plastic strains and forming temperatures.The magnetic parameters of magnetic flux density,coercivity,and remanence were obtained and compared with magnetic flux density as the primary focus.Results showed that machining,cold forming,and hot forming all led to lower magnetic flux density,larger coercivity,and smaller remanence.Magnetic flux density showed a sharp decrease at the start of plastic deformation,but as the strain increased,the decreasing trend gradually reached a constant value.The decrease was much larger for cold forming than for hot forming.For example,at 500 A/m,the degradation of magnetic flux density with a reduction percentage of 5%at room temperature was about 50%,while that of hot forming at 1200°C was about 10%.Results of this research may provide a reference for the future process design of hot-forged claw poles. 展开更多
关键词 low-carbon steel magnetic properties hot forming cold forming surface roughness
在线阅读 下载PDF
High-temperature investigation of mould slag crystallization by single and double hot thermocouple techniques
2
作者 Nathalie Kolbl Irmtraud Marschall Harald Harmuth 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第4期345-354,共10页
Methods for the characterization of mould slag crystallization with special emphasis on the single/double hot thermocouple technique(SHTT/DHTT)are reviewed.In the continuous casting process of steels,horizontal heat t... Methods for the characterization of mould slag crystallization with special emphasis on the single/double hot thermocouple technique(SHTT/DHTT)are reviewed.In the continuous casting process of steels,horizontal heat transfer is mainly influenced by the crystallization behaviour of the mould flux film.Here,both precipitation of crystals out of a liquid phase and devitrification of the glassy film in contact with the mould are of main interest.Therefore,various investigation methods are implemented to characterize different slag properties related to crystallization:a viscometer for determining the break temperature,differential thermal analysis(DTA),confocal scanning laser microscopy,and the water-cooled copper finger test.For near-service conditions,DHTT reveals the most detailed information,including not only the crystallization or devitrification temperature but also the morphology as well as the crystallization velocity.Due to improvements in the device and the representation of the results,a comparison of different samples is possible.Nevertheless,the application field of SHTT/DHTT is restricted to slag systems with low contents of evaporating components.Furthermore,the time required for data analysis is significantly longer than that required for other methods,e.g.DTA.Therefore,the application of DHTT is mainly advisable for mould slag research and development,whereas DTA can also be used for incoming inspections. 展开更多
关键词 SINGLE HOT THERMOCOUPLE TECHNIQUE DOUBLE HOT THERMOCOUPLE TECHNIQUE Mould slag Near-service condition In situ investigation CRYSTALLIZATION
Hot Deformation Behavior of an Ultra-High-Strength Fe-Ni-Co-Based Maraging Steel
3
作者 Le Zhang Wei Wang +2 位作者 M. Babar Shahzad Yi-Yin Shan Ke Yang 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第9期1161-1172,共12页
Hot processing behavior of an ultra-high-strength Fe–Ni–Co-based maraging steel was studied in temperature range of 900–1200℃and strain rate range of 0.001–10 s^-1.Deformation processing parameters and optimum ho... Hot processing behavior of an ultra-high-strength Fe–Ni–Co-based maraging steel was studied in temperature range of 900–1200℃and strain rate range of 0.001–10 s^-1.Deformation processing parameters and optimum hot working window were characterized via flow stress analysis,constitutive equation construction,hot processing map calculation and microstructure evolution,respectively.Critical strain value for dynamic recrystallization was determined through theoretical mathematical differential method:the inflection point ofθ–σand-αθ/ασ-σcurves.It was found that the flow stress increased with the decrease in deformation temperature and increase in the strain rate.The power dissipation maps in the strain range of 0.1–0.6 were entirely similar with the tendency of contour lines which implied that strain had no strong effect on the dissipation maps.Nevertheless,the instability maps showed obvious strain sensitivity with increasing strain,which was ascribed to the flow localization and instability.The optimized hot processing window of the experimental steel was obtained as 1100–1200℃/0.001–1 s^-1 and 1000–1100℃/0.001–0.1 s^-1,with the efficiency range of 20–40%.Owing to high Mo content in the experimental steel,high dynamic activation energy,Q=439.311 kJ mol^-1,was achieved,indicating that dynamic recrystallization was difficult to occur in the hot deformation process,which was proved via microstructure analysis under different hot deformation conditions. 展开更多
关键词 Maraging steel HOT working Dynamic RECRYSTALLIZATION CONSTITUTIVE EQUATION HOT PROCESSING MAP
寒性与热性中药对小鼠棕色脂肪组织中产热调节蛋白UCP1基因和蛋白表达的影响
4
作者 杨玉娇 王朋倩 +7 位作者 张淼 吴茵 石忠峰 周炜炜 孟晶 霍海如 隋峰 韩亮 《中华中医药杂志》 CAS CSCD 北大核心 2019年第4期1679-1681,共3页
目的:观察寒性与热性中药对机体产热的关键节点解偶联蛋白-1(UCP1)的调节作用,寻找寒热药性的共性的生物学规律。方法:分别采用Real-time RCR和Western blot的方法研究寒性中药(黄连、黄芩、黄柏)和热性中药(白芷、肉桂、胡椒)对小鼠棕... 目的:观察寒性与热性中药对机体产热的关键节点解偶联蛋白-1(UCP1)的调节作用,寻找寒热药性的共性的生物学规律。方法:分别采用Real-time RCR和Western blot的方法研究寒性中药(黄连、黄芩、黄柏)和热性中药(白芷、肉桂、胡椒)对小鼠棕色脂肪组织中UCP1 mRNA和蛋白表达的影响。结果:寒性中药对UCP1 mRNA和蛋白表达均有显著下调作用(P<0.01,P<0.05);热性中药除胡椒外对UCP1 mRNA和蛋白表达均有上调作用(P<0.01)。结论:在基因和蛋白层面调节UCP1表达的生物效应可能是寒性与热性中药的共性特征之一,与中药药性的寒热性表征相关。 展开更多
关键词 寒性 热性 中药 解偶联蛋白 基因 蛋白 寒热性表征
Hot compression deformation behavior of biomedical Ni-Ti alloy
5
作者 Zhen Wang Xiao-Wen Xu Bing Zhang 《稀有金属:英文版》 SCIE EI CAS CSCD 2019年第7期609-619,共11页
Biomedical Ti-55.78 (wt%) Ni alloy samples were prepared by vacuum induction melting, and their hot compression deformation behavior was studied in the deformation temperature range of 750-950℃, the strain rate range... Biomedical Ti-55.78 (wt%) Ni alloy samples were prepared by vacuum induction melting, and their hot compression deformation behavior was studied in the deformation temperature range of 750-950℃, the strain rate range of 0.001-1.000 s^-1 and the true strain range of 0.1 -0.7. The constitutive equation of the as-cast biomedical Ni-Ti alloy was established based on the Arrhenius constitutive model, and error analysis of the constitutive equation was carried out. The processing zone and unstable thermal deformation zone of the as-cast biomedical Ni-Ti alloy were obtained by establishing hot processing maps based on a dynamic material model. The results showed that deformation temperature and strain rate were the main factors affecting the flow stress. The results of error verification of the constitutive equation show that the predicted flow stress curves agree well with the measured ones. Therefore, the constitutive equation based on Arrhenius can accurately predict the high temperature flow stress of as-cast biomedical Ni-Ti alloy. The optimum parameters for forging process of biomedical Ni-Ti alloy are the strain rate less than 0.003 s^-1 and the hot deformation temperature range of 930-950℃. 展开更多
关键词 BIOMEDICAL NI-TI ALLOY HOT compression deformation Constitutive equation HOT processing map
Geological characteristics and analysis of hydrothermal genesis in the Suijiang-1 well in Yunnan Province, China 预览
6
作者 SHU Qin-feng WEI Liang-shuai LI Xiao 《地下水科学与工程:英文版》 2019年第1期53-60,共8页
The geothermal water hydrochemistry and isotopic characteristics of boreholes in the Suijiang-1 well in Yunnan Province were studied based on the actual drilling geology, regional geological structure and hydrogeologi... The geothermal water hydrochemistry and isotopic characteristics of boreholes in the Suijiang-1 well in Yunnan Province were studied based on the actual drilling geology, regional geological structure and hydrogeological conditions. The analysis results show that the geothermal water is SO4-Ca·Mg type, the recharge elevation is 1 381-1 646 m, the recharge source is atmospheric precipitation, the geothermal reservoir temperature is 42-45 ℃, and the geothermal water is controlled by lithology and geological structure conditions of study area. Atmospheric precipitation enters the groundwater circulation system through the surface karst form of the Wujiaobao anticline, northwest-southeast tensile faults, fissures and karst depression, and geothermal water formed through the rising deep cycle water temperature, then blocked by the double rivers’ fault zone and drilling explosion. 展开更多
关键词 GEOTHERMAL water HYDROCHEMISTRY Origin ANALYSIS of hot spring
在线阅读 下载PDF
Hot deformation behaviors of a 9Cr oxide dispersion-strengthened steel and its microstructure characterization 预览
7
作者 Yu Shao Li-ming Yu +3 位作者 Yong-chang Liu Zong-qing Ma Hui-jun Li Jie-feng Wu 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第5期597-610,共14页
The hot deformation behaviors of a 9Cr oxide dispersion-strengthened (9Cr-ODS) steel fabricated by mechanical alloying and hot isostatic pressing (HIP) were investigated.Hot compression deformation experiments were co... The hot deformation behaviors of a 9Cr oxide dispersion-strengthened (9Cr-ODS) steel fabricated by mechanical alloying and hot isostatic pressing (HIP) were investigated.Hot compression deformation experiments were conducted on a Gleeble 3500 simulator in a temperature range of 950–1100℃ and strain rate range of 0.001–1 s^-1.The constitutive equation that can accurately describe the relationship between the rheological stress and the strain rate of the 9Cr-ODS steel was established,and the deformation activation energy was calculated as 780.817 kJ/mol according to the data obtained.The processing maps of 9Cr-ODS in the strain range of 0.1–0.6 were also developed.The results show that the region with high power dissipation efficiency corresponds to a completely recrystallized structure.The optimal processing conditions were determined as a temperature range of 1000–1050℃ with strain rate between 0.003 and 0.01 s^-1. 展开更多
关键词 hot deformation CONSTITUTIVE EQUATIONS processing MAPS MICROSTRUCTURAL evolution
在线阅读 下载PDF
Hot corrosion behavior and mechanism of FGH96 P/M superalloy in molten NaCl–Na2SO4 salts
8
作者 He Jiang Jian-Xin Dong +2 位作者 Mai-Cang Zhang Lei Zheng Zhi-Hao Yao 《稀有金属:英文版》 SCIE EI CAS CSCD 2019年第2期173-180,共8页
Hot corrosion behavior of FGH96 powder metallurgy(P/M) superalloy in 25 % NaCl + 75 % Na2SO4 molten salts at 650, 700, and 750 ℃ was investigated in this paper. The methods of mass loss measurement, X-ray diffraction... Hot corrosion behavior of FGH96 powder metallurgy(P/M) superalloy in 25 % NaCl + 75 % Na2SO4 molten salts at 650, 700, and 750 ℃ was investigated in this paper. The methods of mass loss measurement, X-ray diffraction(XRD), scanning electron microscopy(SEM),and energy-dispersive spectroscopy(EDS) were used here.The experimental results show that hot corrosion kinetics follows a square power law at 650 ℃, while a linear one at 700 and 750 ℃. The corrosion layer is detected to be composed of Cr2O3, NiO, and Ni2S3 at each temperature.The cross-sectional morphologies and corresponding elemental maps indicate that the corrosion layer is a stratified structure of oxide and sulfide. The results and analyses confirm that the hot corrosion mechanism of FGH96 P/M superalloy is a cooperate process of oxidation and sulfidation. Furthermore, the relatively higher concentrations of Cr, Co, and Ti provide better corrosion resistance to the attack of S and Cl^-. 展开更多
关键词 Nickel-based SUPERALLOY FGH96 Hot corrosion MOLTEN SALTS
Study on the thermal deformation behavior and microstructure of FGH96 heat extrusion alloy during two-pass hot deformation 预览
9
作者 Bin Fang Gao-feng Tian +3 位作者 Zhen Ji Meng-ya Wang Cheng-chang Jia Shan-wu Yang 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第5期657-663,共7页
The change rules associated with hot deformation of FGH96 alloy were investigated by isothermal two-pass hot deformation tests in the temperature range 1050–1125℃ and at strain rates ranging from 0.001 to 0.1 s^-1 o... The change rules associated with hot deformation of FGH96 alloy were investigated by isothermal two-pass hot deformation tests in the temperature range 1050–1125℃ and at strain rates ranging from 0.001 to 0.1 s^-1 on a Gleeble 3500 thermo-simulation machine.The results showed that the softening degree of the alloy between passes decreases with increasing temperature and decreasing strain rates.The critical strain of the first-pass is greater than that of the second-pass.The true stress–true strain curves showed that single-peak dynamic recrystallization,multi- peak dynamic recrystallization,and dynamic response occur when the strain rate is 0.1,0.01,and 0.001 s^-1,respectively.The alloy contains three different grain structures after hot deformation: partially recrystallized tissue,completely fine recrystallized tissue,coarse-grained grains.The small-angle grain boundaries increase with increasing temperature.Increasing strain rates cause the small-angle grain boundaries to first increase and then decrease. 展开更多
关键词 FGH96 super-alloy two-pass hot deformation MICROSTRUCTURE grain ORIENTATION
在线阅读 下载PDF
Influence of Glass Dust on Properties of Alumina-carbon Refractories 预览
10
作者 MA Weikui LIU Guoqi +2 位作者 YU Jianbin QIAN Fan YANG Wengang 《中国耐火材料:英文版》 CAS 2019年第4期40-44,共5页
In order to improve the properties of alumina-carbon refractories,specimens were prepared using white fused corundum,zirconia-mullite and flake graphite as the raw materials,phenolic resin as the binder,adding differe... In order to improve the properties of alumina-carbon refractories,specimens were prepared using white fused corundum,zirconia-mullite and flake graphite as the raw materials,phenolic resin as the binder,adding different mass fractions(1.5%,2.0%,and 2.5%,respectively)of glass dust,cold isostatic pressing by 120 MPa,drying and firing at 900℃for 3 h.Effects of the glass dust addition on the apparent porosity,bulk density,cold modulus of rupture,hot modulus of rupture and thermal shock resistance were studied.The results show that the cold modulus of rupture of the specimens is improved significantly as the results of glass dust accelerating sintering.However,the hot modulus of rupture decreases.As the glass phase buffers the strain produced by thermal shock,the thermal shock resistance of alumina-carbon specimens is improved,especially for low carbon alumina-carbon materials. 展开更多
关键词 alumina-carbon material glass phase hot modulus of rupture thermal shock resistance
在线阅读 免费下载
TOURISM BRINGING PEOPLE TOGETHER Fourth Maritime Silk Road International Tourism Festival in‘Hot Springs’city 预览
11
作者 Si Thu Tun 《中国东盟报道》 2019年第1期52-53,共2页
Humid air awaited my arrival at Fuzhou Changle Airport.Upon emerging from the airport,I found myself overwhelmed by mountains embracing Fuzhou.I also couldn’t help but notice roots hanging to the ground from the bran... Humid air awaited my arrival at Fuzhou Changle Airport.Upon emerging from the airport,I found myself overwhelmed by mountains embracing Fuzhou.I also couldn’t help but notice roots hanging to the ground from the branches of banyan trees on either side of the streets. 展开更多
关键词 EITHER Hot from ALSO HELP but of to
在线阅读 下载PDF
Silica nanocone array as a template for fabricating a plasmon induced hot electron photodetector
12
作者 Zhiqiang Yang Kang Du +6 位作者 Fanfan Lu Yang Pang Shijia Hua Xuetao Gan Wending Zhang Soo Jin Chua Ting Mei 《光子学研究:英文版》 CSCD 2019年第3期294-299,共6页
Plasmon induced hot electrons have attracted a great deal of interest as a novel route for photodetection and lightenergy harvesting. Herein, we report a hot electron photodetector in which a large array of nanocones ... Plasmon induced hot electrons have attracted a great deal of interest as a novel route for photodetection and lightenergy harvesting. Herein, we report a hot electron photodetector in which a large array of nanocones deposited sequentially with aluminum, titanium dioxide, and gold films can be integrated functionally with nanophotonics and microelectronics. The device exhibits a strong photoelectric response at around 620 nm with a responsivity of 180 μA/W under short-circuit conditions with a significant increase under 1 V reverse bias to 360 μA/W. The increase in responsivity and a red shift in the peak value with increasing bias voltage indicate that the bias causes an increase in the hot electron tunneling effect. Our approach will be advantageous for the implementation of the proposed architecture on a vast variety of integrated optoelectronic devices. 展开更多
关键词 SILICA NANOCONE ARRAY PLASMON INDUCED hot electron PHOTODETECTOR
Hot Deformation and Corrosion Resistance of High-Strength Low-Alloy Steel
13
作者 Wilasinee Kingkam Cheng-Zhi Zhao +2 位作者 Hong Li He-Xin Zhang Zhi-Ming Li 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第4期495-505,共11页
The hot deformation characteristics and the corrosion behavior of a high-strength low-alloy(HSLA) steel were investigated at deformation temperatures ranging from 800 to 1100 ℃ and strain rates ranging from 0.1 to 10... The hot deformation characteristics and the corrosion behavior of a high-strength low-alloy(HSLA) steel were investigated at deformation temperatures ranging from 800 to 1100 ℃ and strain rates ranging from 0.1 to 10 s^-1 using an MMS-200 thermal simulation testing machine. Based on the flow curves from the experiment, the effects of temperature and strain rate on the dynamic recrystallization behavior were analyzed. The flow stress decreased with increasing deformation temperature and decreasing strain rate. With the assistance of the process parameters, constitutive equations were used to obtain the activation energy and hot working equation. The hot deformation activation energy of HSLA steel in this work was 351.87 kJ/mol. The work hardening rate was used to determine the critical stress(strain) or the peak stress(strain). The dependence of these characteristic values on the Zener-Hollomon parameter was found. A dynamic recrystallization kinetics model of the tested HSLA steel was constructed, and the validity of the model was confirmed by the experimental results. Observation of the microstructures indicated that the grain size increased with increasing deformation temperature,which led to a lowered corrosion resistance of the specimens. 展开更多
关键词 Dynamic RECRYSTALLIZATION POTENTIODYNAMIC POLARIZATION Hot deformation Flow stress HIGH-STRENGTH low-alloy steel
Effect of Nb Content on the Hot Deformation Behavior of S460ML Steel
14
作者 Yu-Cheng Zhang Zhen-Sheng Meng +3 位作者 Yang Meng Xin-Hua Ju Zhong-Hang Jiang Ze-Jun Ma 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第4期526-534,共9页
The hot deformation behavior of S460 ML steel with different Nb contents was investigated by single-pass compression experiment on the Gleeble-1500 thermo-machine simulator at deformation temperatures ranging from 900... The hot deformation behavior of S460 ML steel with different Nb contents was investigated by single-pass compression experiment on the Gleeble-1500 thermo-machine simulator at deformation temperatures ranging from 900 to 1200 ℃ and strain rates from 0.1 to 5.0 s^-1. The critical strain of dynamic recrystallization(DRC) under different conditions was determined by using working hardening rate-strain curves. The relationship between critical strain and peak strain of DRC was discussed. By means of regression analysis method, the hot deformation activation energy of steels and the mathematical model for predicting DRC critical strain were calculated and established, respectively. The results showed that DRC occurred during hot deformation. As the deformation temperature increased and strain rate decreased, the critical strain of DRC decreased. The critical strain(εc) showed linear relationship with peak strain(εp). As Nb content increased,the needed deformation temperature for occurring DRC increased, while the needed strain rate for it decreased. The activation energy for hot deformation of S460 ML steel increased with increasing Nb content. 展开更多
关键词 Dynamic RECRYSTALLIZATION CRITICAL STRAIN NB CONTENT DEFORMATION temperature STRAIN rate Hot DEFORMATION
Suitability and Construction of Self-Insulation Walls in the Hot Summer and Cold Winter Zone of Southern Shaanxi 预览
15
作者 LI Xueping 《景观研究:英文版》 2019年第1期15-19,共5页
In this paper,the suitability and construction technology of self-insulation walls were studied under the specific climatic conditions and regional resources of Hanzhong and Ankang in the hot summer and cold winter zo... In this paper,the suitability and construction technology of self-insulation walls were studied under the specific climatic conditions and regional resources of Hanzhong and Ankang in the hot summer and cold winter zone of Southern Shaanxi.Through the calculation of heat transfer coefficient and thermal inertia index,combined with the specifications of the shale hollow brick and aerated concrete block of Hanzhong and Ankang in southern Shaanxi,the thermal performance and suitable thickness of the external wall using self-insulation materials that meet the Design Standard for Energy Efficiency of Residential Buildings(DBJ61-65-2011)in Shaanxi Province were obtained.The results showed that the self-insulation wall had technical suitability in the hot summer and cold winter zone.The research results provide not only a theoretical basis for the external wall insulation design of urban residential buildings in the hot summer and cold winter zone of southern Shaanxi,but also a reference for designers to carry out energy-saving design of external walls of residential buildings in other similar climate zones. 展开更多
关键词 SELF-INSULATION wall SOUTHERN SHAANXI Hot SUMMER and cold winter zone SUITABILITY CONSTRUCTION technology
在线阅读 下载PDF
Hot deformation behavior and workability characteristic of a fine-grained Mg–8Sn–2Zn–2Al alloy with processing map
16
作者 Weili Cheng Yang Bai +3 位作者 Shichao Ma Lifei Wang Hongxia Wang Hui Yu 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第6期1198-1209,共12页
The hot deformation behavior of a fine-grained Mg–8 Sn–2 Zn–2 Al(TZA822, in wt%) alloy was investigated in the temperature range of 150–350°C and the strain rate of 0.01–10 s^-1 employing thermomechanical si... The hot deformation behavior of a fine-grained Mg–8 Sn–2 Zn–2 Al(TZA822, in wt%) alloy was investigated in the temperature range of 150–350°C and the strain rate of 0.01–10 s^-1 employing thermomechanical simulator. In most of the cases, the material showed typical dynamic recrystallization(DRX) features i.e., a signal peak value followed by a gradual decrease or to reach a steady state. The work hardening rate was found to increase with decreasing temperature and increasing strain rate, while strain rates had great effects on work hardening behavior. Meanwhile, the constitutive analysis indicated that cross-slip of dislocations was likely to be the dominant deformation mechanism. In addition, the processing map at the strain of 0.1–0.7 showed two stability domains with high power dissipation efficiencies and the optimum hot working parameters for the studied alloy was determined to be 350°C/0.01 s^-1 and 350°C/10 s^-1, at which continuous DRX(CDRX) and discontinuous DRX(DDRX) as main softening mechanism. The instability regions occurred at 200–250°C/10 s^-1 and the main flow instability mechanism was twinning and/or flow localization bands, which were prone to induce cracks and caused in-consistent mechanical properties of the alloy. 展开更多
关键词 Mg-Sn based alloy Hot DEFORMATION Processing map Dynamic RECRYSTALLIZATION
Hot Air Generator Using Natural Convection Flow in a Heated Channel 预览
17
作者 Bushra AlGarawi Zeinebou Yahya 《能源与动力工程:英文版》 2019年第4期131-136,共6页
Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impedin... Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impeding the spread of hot air producing technology is the lack of homogeneity of the heat flow coming from hot air generators as well as an inadequate flow rate.The most of the existing hot air generators require to be supported by systems that can increase the low volumetric flow and the air temperature of these generators,through increasing the speed of the flow of air emitted or lifting the drawer Heat,which contributes to raising the overall cost.However,to improve the thermal and dynamic quality of the hot air flow produced by the generator,a numerical investigation of the free convection flow inside two different configurations is presented in this thesis.The primary objective of this work is to predict the behavior of the flow inside tow configurations,the first one consists of a vertical cylinder with heated walls,and the second configuration is an open-ended vertical cylinder with a hot disc placed at the entrance(configuration A,configuration B).This work characterizes through the examination of this flow,the variables that control an air emission with high flow rate and a high and homogeneous temperature to represent the appropriate criteria that should be respected to obtain a hot air generator overcoming the previously mentioned constraints.Furthermore;the results of this work show the influence the boundary conditions and Rayleigh number on the resulting flow. 展开更多
关键词 Hot air GENERATOR NATURAL CONVECTION vertical CHANNEL NAVIER-STOKES equations finite volume method
在线阅读 下载PDF
Space weather 预览
18
作者 Engeli Haupt 《新世纪智能》 2019年第10期35-37,共3页
Very hot and very cold Have you ever wondered how cold it is in space? Well, apparently the vacuum of space has no temperature. But, put an object in space and it is going to experience some extreme temperatures:if le... Very hot and very cold Have you ever wondered how cold it is in space? Well, apparently the vacuum of space has no temperature. But, put an object in space and it is going to experience some extreme temperatures:if left in the sunlight an object can heat up to 260°Celsius, roughly 200 degrees hotter than the hottest place on Earth. In the shade temperatures can drop to-100℃. This is much colder than the coldest places on our planet:Antarctica has an average temperature of-55℃with a record low of-89.2℃. If you want to visit Pluto, don’t forget to pack your space jacket, because it can get as cold as-260°Celsius! 展开更多
关键词 Very HOT IS in SPACE PACK YOUR SPACE JACKET
在线阅读 下载PDF
FEM analysis and experimental investigation of force and chip formation on hot turning of Inconel 625 预览
19
作者 Asit Kumar Parida Kalipada Maity 《Defence Technology(防务技术)》 CAS CSCD 2019年第6期853-860,共8页
This study investigates the hot machining of Inconel 625 alloy by using flame heating under different machining conditions using finite element analysis(FEM).Turning tests are performed at different cutting speeds and... This study investigates the hot machining of Inconel 625 alloy by using flame heating under different machining conditions using finite element analysis(FEM).Turning tests are performed at different cutting speeds and heating temperatures using uncoated carbide insert by DEFORM software.Significant reduction in cutting force and tool wear has achieved at heating conditions compared to room temperature.Highest tool life is achieved at the highest cutting speed and higher heating temperature condition.At heating conditions of the 600℃ continuous chip is formed whereas at room temperature saw-tooth chip formation is observed.A significant agreement is achieved between simulated and experimental cutting forces and chip morphology.The effect of feed rates and depth of cuts are also studied experimentally during turning of Inconel 625 in a systematic manner. 展开更多
关键词 Hot machining FORCE Inconel 625 Surface roughness Chip morphology
在线阅读 免费下载
The Two Hyperplane Conjecture
20
作者 David JERISON 《数学学报:英文版》 SCIE CSCD 2019年第6期728-748,共21页
We introduce a conjecture that we call the Two Hyperplane Conjecture, saying that an isoperimetric surface that divides a convex body in half by volume is trapped between parallel hyperplanes. The conjecture is motiva... We introduce a conjecture that we call the Two Hyperplane Conjecture, saying that an isoperimetric surface that divides a convex body in half by volume is trapped between parallel hyperplanes. The conjecture is motivated by an approach we propose to the Hots Spots Conjecture of J. Rauch using deformation and Lipschitz bounds for level sets of eigenfunctions. We will relate this approach to quantitative connectivity properties of level sets of solutions to elliptic variational problems, including isoperimetric inequalities, Poincar′e inequalities, Harnack inequalities, and NTA(non-tangentially accessibility). This paper mostly asks questions rather than answering them, while recasting known results in a new light. Its main theme is that the level sets of least energy solutions to scalar variational problems should be as simple as possible. 展开更多
关键词 Minimal surfaces ISOPERIMETRIC ELLIPTIC VARIATIONAL problems hot SPOTS CONJECTURE
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈