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Experimental and numerical study on plasma nitriding of AISI P20 mold steel

International Journal of Minerals,Metallurgy and Materials 2016年第9期23卷 1065-1075页

作者： N.Nayebpash.ee H.Vafaeenezhad sh.Kheirandish.M.Soltanieh Materials Processing Simulation Laboratory(MPS-LAB) School of Materials and Metallurgical EngineeringIran University of Science and Technology(IUST) School of Materials and Metallurgical Engineering Iran University of Science and Technology(IUST)

In this study, plasma nitriding was used to fabricate a hard protective layer on AISI P20 steel, at three process temperatures（450℃, 500℃, and 550℃） and over a range of time periods（2.5, 5, 7.5, and 10 h）, and at a fixed gas N2：H2 ratio of 75vol%：25vol%. The morphology of samples was studied using optical microscopy and scanning electron microscopy, and the formed phase of each sample was determined by X-ray diffraction. The elemental depth profile was measured by energy dispersive X-ray spectroscopy, wavelength dispersive spectroscopy, and glow dispersive spectroscopy. The hardness profile of the samples was identified, and the microhardness profile from the surface to the sample center was recorded. The results sh.w that ε-nitride is the dominant species after carrying out plasma nitriding in all strategies and that the plasma nitriding process improves the hardness up to more than three times. It is found that as the time and temperature of the process increase, the hardness and hardness depth of the diffusion zone considerably increase. Furthermore, artificial neural networks were used to predict the effects of operational parameters on the mechanical properties of plastic mold steel. The plasma temperature, running time of imposition, and target distance to the sample surface were all used as network inputs; Vickers hardness measurements were given as the output of the model. The model accurately reproduced the experimental outcomes under different operational conditions; therefore, it can be used in the effective simulation of the plasma nitriding process in AISI P20 steel.

关键词： tool steel plasma nitriding sputtering neural networks

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Estimation of wind speeds inside Super Typhoon Nepartak from AMSR2 low-frequency brightness temperatures

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Frontiers of Earth Science 2019年第1期13卷 124-131页

作者： Lei ZHANG Xiaobin YIN Hanqing sh.Zhenzhan WANG Qing XU Institute of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China Beijing Piesat Information Technology Co.Ltd Beijing 100195China National Space Science Center Chinese Academy of SciencesBeijing 100190China College of Oceanography Hohai UniversityNanjing 211101China

Accurate estimations of typhoon-level winds are highly desired over the westem Pacific Ocean.A wind speed retrieval algorithm is used to retrieve the wind speeds within Super Typhoon Nepartak (2016)using 6.9- and 10.7-GHz brightness temperatures from the Japanese Advanced Microwave Scanning Radiometer 2 (AMSR2) sensor on board the Global Change Observation Mission-Water 1 (GCOM-Wl)*** results sh.w that the retrieved wind speeds clearly represent the intensification process of Super Typhoon Nepartak.A good agreement is found between the retrieved wind speeds and the Soil Moisture Active Passive wind speed *** mean bias is 0.51 m/s,and the root-mean-square difference is 1.93 m/s between *** retrieved maximum wind speeds are 59.6 m/s at 04:45 UTC on July 6 and 71.3 m/s at 16:58 UTC on July *** two results demonstrate good agreement with the results reported by the China Meteorological Administration and the Joint Typhoon Warning *** addition,Feng-Yun 2G (FY-2G) satellite infrared images,Feng-Yun 3C (FY-3C)microwave atmospheric sounder data,and AMSR2 brightness temperature images are also used to describe the development and structure of Super Typhoon Nepartak.

关键词： microwave radiometer sea surface wind retrieval AMSR2 Nepartak SMAP

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Characteristic Assessment of Stabilized Polyacrylonitrile Nanowebs for the Production of Activated Carbon Nano-Sorbents

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Chinese Journal of Polymer Science 2014年第4期32卷 449-457页

作者： S.Rafiei B.Noroozi sh.Arbab A.K.Haghi Department of Textile Engineering University of Guilan

Polyacrylonitrile （PAN） nanofibers with average diameter of 300 nm were produced by electro-spinning. The nanofibers were stabilized at different temperatures in the range of 180-270 ℃in several duration times and heating rates. Fourier transforms infrared （FTIR） spectroscopy, differential scanning calorimetry （DSC） and X-ray diffraction （XRD） analyzing techniques were employed to measure the extent of stabilization reaction. By all procedures, the ranges of temperature and duration time recommended were about 250-270 ℃ and 1-2 h, respectively. Increasing the activation temperature from 800 ℃ to 1200 ℃ caused porosity and pore volume development up to 60% and 0.532 cm3/g, respectively. Pore width of all samples was calculated to be about 0.7 nm confirming micro-pore structure of the produced PAN based activated carbon nanofibers. Comparing dye adsorption for different adsorbents including chitin and granular activated carbon （GAC） sh.wed the highest efficiency for the produced activated carbon nanofibers （ACNFs）.

关键词： Polyacrylonitrile Electro-spinning Stabilization Activated carbon nanofibers Adsorbent.

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Involvement of Male Youth into Accidents in Upper Egypt: Pattern and Risk Analysis

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Health 2015年第8期7卷 965-975页

作者： Raouf M. Afifi Sameh sh. Zaytou Ahmed A. El Raggal Amani Qulali Hesh.m A. K. Ayoub Community Health Institute International Management-Health Services Inc. Indianapolis Indiana USA Department of Community Medicine and Internal Medicine South Valley University Quena Egypt Health Department Egyptian Atomic Energy Authority Ministry of Electricity & Energy Cairo Egypt Department of Internal Medicine Military Medical Academy Cairo Egypt

Background: Accidents pose a serious threat to health and economy in Egypt. Objectives: To identify and analyze the epidemiological factors associated with different types of accidents among adult males in Upper Egypt. Methods: A sample of 500 Egyptian males 20 - 28 years of age attending for health care at Quena University Hospital (QUH) or affiliated health institutions in South Egyptian governorates of Luxor and Red Sea was studied. The demographic, socioeconomic, and habitual data, as well as health status, medical history, and history of engagement into accidents for the recruits all were evaluated. Results: Accidents occurrences accounted up to 23/500 (4.6%) of the studied group. Road traffic accidents (RTAs) represented the highest percentage (30.4%), followed by street fights (21.7%) and animal bites (13.1%). Occupational accidents, electrical injuries, and near-drowning, all were equally encountered (8.7%), whereas falls and burns were least prevalent (4.3% each). Drug abuse, manual work, obesity, and having epilepsy were significant risk factors for accident injuries (OR = 6.35, 95% CI: 1.64 - 24.58, OR = 3.36, 95% CI: 1.22 - 9.73, OR = 4.81, 95% CI: 1.50 - 15.46, OR = 45.33, 95% CI: 3.94 - 518.01, respectively). Conclusions: Engagement of young Upper Egyptian males into accidents is alarming. Most of the accident mechanisms encountered are preventable. Enforcement of standard occupational, traffic and public safety laws is needed to minimize the burden of accidents upon the public health and economy in Upper Egypt.

关键词： Accidents Epidemiology Males Upper Egypt

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Purification and Some Properties of Endo-1,4-β-Glucanases of Trichoderma harzianum UzCF-28

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Open Journal of Applied Sciences 2016年第8期6卷 514-523页

作者： N. sh. Azimova D. M. Khamidov M. B. Djumagulov Z. S. sh.kirov Institute of Microbiology of Uzbekistan Academy of Sciences Tashkent Republic of Uzbekistan

This work aimed at isolation, purification and study of biochemical features of cellulolytic enzymes synthesized by Trichoderma harzianum UzCF-28 strain. Strain UzCF-28 revealed a high cellulolytic activity during submerged cultivation in the liquid culture on modified Mandels nutrient medium, where wheat straw was used as a source of carbon. As a result of purification by precipitation with ammonium sulfate and further ion exchange chromatography, two isoforms of endo- 1,4-β-glucanase-EG II and EG III with molecular weight of 135 and 75 kDa respectively were revealed. The pH optimum for EG I and EG III was 4.5, while for EG II—4.7, irrespective of the applied substrates—either CMC or “Whatman filter” paper. Heating up to 40°C of EG III did not lead to its inactivation, and on the contrary, its activity increased by more than three times comparing to the initial activity of the enzyme, i.e. thermostability of EG III among tested enzymes significantly varied.

关键词： Trichoderma harzianum Enzyme Endo-1 4-β-Glucanase Purification

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Cooling process of liquid propellant rocket by means of kerosene-alumina nanofluid

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Propulsion and Power Research 2016年第4期5卷 279-286页

作者： Mostafa Mahmoodi sh.Kandelousi Department of Aerospace Engineering Malek-Ashtar University of TechnologyTehranIran Department of Mechanical Engineering Babol University of TechnologyBabolIran

Heat transfer augmentation of kerosene-alumina nanofluid is studied for the possible use in the regenerative cooling channel of semi cryogenic *** basic partial differential equations are reduced to oidinary differential equations which are solved using differential transformation *** and temperature profiles as well as the skin friction coefficient and Nusselt number are *** influence of pertinent parameters such as nanofluid volume fraction,viscosity parameter and Eckert number on the flow and heat transfer characteristics is *** results indicate that adding alumina into the fuel of liquid rocket engine(kerosene)can be considered as the way of enhancing cooling process of chamber and nozzle *** number is an increasing function of viscosity parameter and nanoparticle volume fraction while it is a decreasing Junction of Eckert number.

关键词： Liquid propellant rocket Kerosene Alumina Nanofluid Heat transfer

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A Study on the Wear Behaviour of Dual Phase Steels

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Journal of Materials Science & Technology 2007年第1期23卷 107-110页

作者： V.Abouei H.Saghafian sh.Kheirandish.Kh.Ranjbar Department of Metallurgy and Materials Engineering Iran University of Science and TechnologyIran sh.hid Chamran University Iran

Dual phase （DP） steels containing four different amounts of martensite ranging from 43 vol. pct to 81 vol. pct have been developed from 0.2 wt pct carbon steel by intercritical heat treatment at a fixed temperature of 780℃ with varying holding times followed by water quenching. Dry sliding wear tests have been conducted on DP steels using a pin- on-disk machine under different normal loads of 61.3, 68.5, 75.7 and 82.6 N and at a constant sliding speed of 1.20 m/s. At these loads, the mechanism of wear is primarily delamination, which has been confirmed by SEM micrographs of subsurface and wear debris of samples. Wear properties have been found to improve with the increase in martensite volume fraction in dual phase steels.

关键词： Wear Dual phase steel Microstructure

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Lead-promoted Barbier-type reaction of aldehydes with propargyl bromides in aqueous media

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Chinese Journal of Chemistry 1997年第4期15卷 361-365页

作者： Zhou, JY Sun, GF Zhang, MF Jia, Y Wu, sh Department of Chemistry Fudan University Shanghai 2004433 China

This paper reports that the reaction of the propargyl bromides with aldehydes promoted by powdered lead in aqueous media. The selectivity and possible mechanism of these reactions are discussed. The yields of products for reaction of propargyl bromide are 31 similar to 71%. The ratios of allenyl alcohol and homopropargyl alcohol are 1:1.5 to 1:3. The product for reaction of phenyl propargyl bromide is allenyl alcohol and the yields are 52 similar to 84%.

关键词： lead reagent Barbier-type reaction propargyl bromides aqueous media

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Synergistic Effect in Special Selectivity Mixed Gas Chromatographic Stationary Phase in the Separation of Aromatic Compounds

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Chinese Chemical Letters 1998年第2期9卷 151-155页

作者： Yuan, LM Fu, RN Gui, sh.Chen, XX Dai, RJ Yunnan Normal Univ Dept Chem Kunming 650092 Peoples R China Beijing Inst Technol Dept Chem Engn Beijing 100081 Peoples R China Yunnan Normal Univ Solar Energy Res Inst Kunming 650092 Peoples R China

The gas chromatographic separations of aromatic compounds using special mixed stationary phases consisting of pp-beta-CD+AgNO3, pp-beta-CD+TINO3, pp-beta-CD+di-n-butly phthalate, pp-beta-CD+BPBHpB liquid crystalline, and bentone-34+AgNO3 were investigated. Besides pp-beta-CD+di-n-butyl phthalate, most of the separations deviated from the additivity and a synergistic effect was observed. The separation effects depend on the temperature and how mixing is accomplish.d.

关键词： gas chromatography mixed stationary phase synergistic effect aromatic compounds

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Age of the sh.hewan rapakivi granite in the Qinling Orogen, China, and its constraints on the end time of the main erogenic stage of this orogen

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Chinese Science Bulletin 1999年第21期44卷 2001-2004页

作者： Zhang, ZQ Zhang, GW Tang, sh.Lu, XX Chinese Acad Geosci Inst Geol Beijing 100037 Peoples R China NW Univ Xian Dept Geol Xian 710069 Peoples R China Dept Geol Res Henan Province Zhengzhou 450053 Peoples R China

the Qinling Mountains in central China are a joint orogenic zone between the Sino-Korean (or North China) and the Yangtze (or South China) craton blocks, the two major tectonic units of eastern Asia. On the end time o... 详细信息

关键词： age rapakivi granite orogenic belt Qinling Mountains.

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