检索结果-南通市图书馆

NEW DEVELOPMENTS IN WrOUGHT 718-TYPE SUPErALLOYS

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

Acta Metallurgica Sinica(English Letters) 2005年第1期18卷 39-46页

作者： r.L. kennedy research & Development ATI Allvac 2020 Ashcraft Avenue Monroe North Carolina NC28111-5030 USA

research and development efforts are still very active on 718-type alloys although two major members of this widely used family, 718 and 625, were invented almost a half-century ago. Emphasis in this type of work at ATI Allvac is directed at improving existing alloys and developing new alloys to meet ever-increasing industrial demands. The improvement of existing alloys is exemplified by addition of minor elements P and B in alloy 718. The discovery of the beneficial effect of P and B in wrought alloy 718 led to development of a new, modified alloy, AllvacH 718 Err. A large effort has also been directed at studying the effects of major element modifications in 718-type alloys, and a new alloy, Allvacr 718PlusTM, has been developed. The new alloy has much better high temperature capability, especially thermal stability, approaching the level of Waspaloy but retains excellent processing characteristics, similar to alloy 718. Alloy 718PlusTM should be useful in any 718-type application requiring a higher working temperature. The properties and processing of this alloy are introduced in this paper.

关键词： 718 718 Er 718Plus Waspaloy Al-Ti effect

Analysis of hourly generation patterns at large coal-fired units and implications of transitioning from baseload to load-following electricity supplier

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2019年第3期7卷 468-474页

作者： robert kennedy SMITH U.S. Department of Energy Office of Fossil Energy

Several factors have led to the decline of electricity generation from coal over the past decade, and projections forecast high rates of growth for wind and solar technologies in coming years. This analysis uses hourly generation data from large coal-fired power stations to determine how operations have been modified in recent years and describes the implications of these changes for plant equipment and unit reliability. The data shows increasing variability in intraday generation output that affects nearly all of the units in the sample, but the magnitude of increase varies widely among plants. Outage patterns were examined as was the relationship between renewable energy growth in a region and the changes in coal plant operations. Aggregate direct and indirect costs associated with running coal plants as load-following units have not yet been quantified in large-scale studies on a sector-wide basis, largely due to differences in how specific equipment responds to output fluctuations. Due to findings from the hourly generation data analysis and the high degree of potential impact on coal plant equipment, the study suggests the development of a new modeling tool that will represent the costs of running coal-fired power plants at lower capacity factors.

关键词： Coal generation Emission intensity Baseload power Capacity factor

Evolving carbon dioxide emission rate intensities of coal-fired power plant on U.S. electricity operating systems

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2018年第6期6卷 1103-1112页

作者： robert kennedy SMITH U.S. Department of Energy Office of Fossil Energy

For many years, coal-fired power plant generation comprised the largest share of electricity in the *** sector. While natural gas plants now constitute a greater portion of the total, coal is projected to remain a shrinking but significant component of U.S. electricity production. Natural gas-fired technologies are dispatchable and versatile generation sources, but the recent and anticipated growth of wind and solar technologies will add nondispatchable, intermittent power generation sources to *** grids. Numerous emissions-related benefits arise from the deployment of these technologies, but they must coexist with coal plants, many of which run most efficiently under baseload operating procedures. Historical monthly emissions data has been analyzed on a sample of coal plants to show how modified coal operations have affected plant emission rates, as measured by carbon dioxide emitted per unit of electricity output. Statistically significant correlations between plant capacity factors and emission rate intensity have been observed by the majority of the sample, showing a worsening under more sporadic operations. Since nearly all of the coal plants in the sample are generating less electricity, determining the emission impact of operational decisions will assist policymakers as they seek to minimize total system emissions without severe disruptions to electricity cost and service reliability.

关键词： Coal Emission intensity renewable generation Baseload power generation

Production Process and Properties of a Highly Porous Al Alloy Made Using NaCl Droplets as a Space Holder

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2015年第8期28卷 1034-1040页

作者： Manuela Covaciu Andrew richard kennedy Faculty of Engineering University of Nottingham Faculty of Material Science and Engineering Universitatea Tehnica din Cluj-Napoca School of Engineering Pontificia Universidad Católica de Chile

Porous Al structures have been made using a porogen leaching method but with additional novel steps. In this way, Al-0.25Cu-0.6Si-1.0Mg alloys with interconnected, open cells have been made, with high levels of porosity（up to 89%）. The use of 4 to 5 mm diameter sodium chloride droplets combined with interspersion of the metal powder and droplets in the die and dissolution of the salt before sintering was found to enable easier interspersion of the two components, resulting in good connectivity of the beads via the formation of ‘‘windows＇＇ between the pores, and rapid elimination of salt from the structure. Porous Al with densities in the range of 0.28–0.86 g/cm3 exhibited compressive yield strengths in the range of 0.14 to 7.5 MPa, with no difference being observed between the samples made by this route and by more conventional dissolution of the salt after sintering. These novel steps widen the possibility for porous metal manufacture to other materials, not limited by the need to have a sintering temperature below that for the melting point of salt.

关键词： Aluminium alloy Sodium chloride Porous metal

From mouse to man——a bridge too far?

在线全文

学校读者我要写书评

暂无评论

National Science review 2020年第7期7卷 1258-1259页

作者： Henry kennedy Colette Dehay Univ Lyon Université Claude Bernard Lyon 1 Inserm Stem Cell and Brain Research Institute U1208 Institute of Neuroscience Chinese Academy of Sciences

The contemplation of our demise, particularly via the loss of cognitive functions, is challenging for our species. While we seek to understand our brain and its action as a particularly intriguing manifestation of the physical universe, society also seeks solutions to concrete problems and, here, understanding the brain as an intellectual exercise must be extended to being able to maintain and repair its function. Just how difficult this is be-

关键词：

Thermal bleaching of optical absorption and photoluminescence spectra of γ-irradiated CaF_2:Dy:Pb:Na single crystals

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of rare Earths 2010年第4期28卷 493-497页

作者： S.M. Moses kennedy Department of Physics S.S.N. College of Engineering Rajiv Gandhi Salai Kalavakkam-603 110 Chennai Tamil Nadu India

The variation of the optical absorption (OA) and photoluminescence (PL) spectra with temperature was studied on γ-irradiated CaF2:Dy:Pb:Na single crystals. The OA spectrum showed bands around 2.05, 3.20, 3.82 and 6.20 eV which could be attributed to different sodium associated (SA) colour centres (CCs) such as MNa and rA+ . Heating the crystal indicated the annihilation and formation of different SACCs. The excitation spectrum for the characteristic Dy3+ emission at 2.14 eV immediately after irradiation was...

关键词： calcium fluoride optical absorption photoluminescence colour centres dysprosium lead sodium rare earths

Thermoluminescence studies on γ-irradiated CaF_2:Dy:Pb:Na single crystals

在线全文

学校读者我要写书评

暂无评论

Journal of rare Earths 2009年第2期27卷 187-191页

作者： S.Masilla Moses kennedy Department of Physics SSN College of EngineeringSSN NagarRajiv Gandhi SalaiChennai-603 110Tamil Nadu India

Therrnoluminescence （TL） glow, thermoluminescence emission （TLE） and thermal decay （TD） of optical absorption （OA） bands were studied on γ-irradiated CaF2：Dy （0.010at.%）：Pb （0.188at.%）：Na （0.026at.%） single crystals （hereafter called crystal-I）. The TL glow exhibited four glow peaks in the temperature region 300-500 K. The TL response with dose was studied up to -7.5 kGy. The total glow showed linear, supra linear and exponential growth with dose. The TLE showed bands characteristic of Dy^3＋ ions （around 1.65, 1.87, 2.18 and 2.63 eV） and sodium associated （SA） colour centres （CCs） such as MNa （around 1.67 eV） and XNa （a new SA CC, with an emission band around 2.63 eV）. The OA bands of MNa CC around 3.23 and 2.07 eV were found to decrease with temperature almost in accordance with the TL glow. The r＋A centre absorption around 2.48 eV was found to grow with temperature initially and then decayed. The formation/growth of the CCs r＋A and XNa might be from the conversion of the irradiation produced CC MNa. An attempt was made to explain the TL mechanism in the present system.

关键词： CaF2:Dy:Pb:Na thermoluminescence thermoluminescence emission colour centres rare earths

A column study of the hydro-mechanical behavior of mature fine tailings under atmospheric drying

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2017年第2期27卷 203-209页

作者： Anis roshani Mamadou Fall Kevin kennedy Department of Civil Engineering University of OttawaOttawa KIN 6N5Canada

In this paper, the hydro-mechanical behavior and physical properties of mature fine tailings(MFT) under atmospheric drying are investigated through a column study. In the study, evaporation takes place in the development of suction in the upper parts of the column and increasing suction leads to higher strength in the tailings. After 5 days, the suction in the first lift is around 17 k Pa in the upper part of the *** a second lift is added, the first lift initially loses strength but over a 30 days' period, the strength is recovered to its prior value and suction in the second lift reaches 500 k Pa. The vane shear strength values show a substantial increase in the strength of the MFT after 30 days under atmospheric drying and drainage. The 90% strength found in the column exceeds the threshold(5 k Pa). The hydraulic-mechanical properties of the deposited tailings are closely coupled due to several mechanisms, such as evaporation,drainage, self-consolidation, suction and crack development. The findings of this study will provide a better understanding of the placement behavior of multiple lifts of MFT and thus contribute to reclamation design standards and reduce the use of dedicated disposal areas.

关键词： Tailings Oil sand Environment Drying Multi-lift deposition

Electronic behavior of native oxide films on Ti and TiN during 90-day immersion in electrolytes with different pH levels

在线全文

学校读者我要写书评

暂无评论

rare Metals 2021年第3期40卷 582-589页

作者： Amir Poursaee Golnaz Najaf-Tomaraei Marian S.kennedy Department of Materials Science and Engineering and Glenn Department of Civil Engineering Clemson UniversityClemsonSC 29634USA Department of Materials Science and Engineering Clemson UniversityClemsonSC 29634USA

This work presents the electronic behavior of Ti and TiN thin films when exposed to electrolytes with pH levels of 2,7 and 13 for 90 *** potentio-electrochemical impedance spectroscopy tests were performed on the 100-nm Ti and TiN monolithic films,and MottSchottky analysis of these tests was used to determine the films’ semiconductive behavior and changes in the donor/acceptor *** addition,the flat-band potential of each film’s surface oxide was also *** attempt was made to control oxide formation,and therefore,these tests reflected the native surfaces of these *** the TiN films exhibited n-type semiconductivity in all electrolytes,the Ti films only showed n-type behavior in the acidic(pH=2) and neutral(pH=7) *** semiconductivity of the Ti films transitioned to p-type during exposure to the basic electrolyte(pH=13) after reaching 60 ***,there was a significant increase in the donor densities for both Ti and TiN films when immersed in the basic electrolyte relative to the acidic and neutral electrolytes.

关键词： Ti TiN Thin films Mott-Schottky analysis Semiconductivity