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DEVELOPMENT　OF　incONEL~　ALLOY　783，A　LOW　THERMAL　EXPANSION，CRACK　GROWTH　RESISTANT　SUPERALLOY

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 503-507页

作者： J.H.Thndermann(inco Alloys International, inc., Huntington, WV 25705, USA ) inco Alloys Int inc. Huntington United States

Low thermal expansion superalloys have been used for a number of years in a variety of applications, including gas turbine engines. The low thermal expansion characteristics of the most widely used class of materials are derived from the ferromagnetic characteristics of Ni, Fe, and Co-based austenitic matrices containing little or no *** developments have been aimed at improving the oxidation resistance and stress accelerated grain boundary oxygen (SAGBO) *** alloy 783 is an oxidation resistant, low coefficient of thermal expansion superalloy developed for gas turbine applications. Alloy 783 represents a culmination in the development, of an alloy system with very high alumtnum content that, in addition to forming γ′,causes βaluminide phase precipitation in the austenitic *** type of structure can be processed to resist both SAGBO and general oxidation,while providing low thermal expansion and useful mechanical properties up to 700℃.Key aspects of the alloy's development are presented.

关键词： coefficient of thermal expansion oxidation resistance crack growth resistance,SAGBO incONEL alloy 783,alloy 718,gamma prime phase beta phase

Frequency dispersion effect and parameters extraction method for novel HfO2 as gate dielectric

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Science China(Information Sciences) 2010年第4期53卷 878-884页

作者： ZHAO Aaron TALLAVARJULA Sai Applied Materials inc Sunnyvale CA 94086USA

The electric characteristic of MOS capacitor with HfO2/SiO2/p-Si grown by ALCVD （atom layer chemical vapor deposition） is investigated. The C-V curves show that the accumulation capacitances take on the frequency dispersion at high frequency. For MOS capacitor with ultra thin HfO2/SiO2gate stack, different fabrication processes and measurement equipment will cause parasitic effect. Here an equivalent circuit model that can eliminate the frequency dispersion effect is proposed. The C-V characteristics curve at high frequency shows some distortion because of the bulk defects and the interface states. This paper discusses the distortion of the high frequency MOS C-V characteristic curve. A data processing method is advanced and interface trap density distribution in the band gap is presented. By comparing the ideal C-V curve with the experimental C-V curve, the typical electrical parameters of MOS capacitor are extracted, including the shift of flat-band voltage, the oxide charges and the density of interface traps at the SiO2/Si interface.

关键词： high k gate dielectric HfO2 frequency dispersion equivalent circuit model two-frequency C-V measurement parameters extraction

A History of Fischer-Tropsch Wax Upgrading at BP-from Catalyst Screening Studies to Full Scale Demonstration in Alaska

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Journal of Natural Gas Chemistry 2006年第1期15卷 1-10页

作者： John P. Collins Joep J. H. M. Font Freide Barry Nay BP Exploration America inc. BP Exploration Operating Company

Conversion of Fischer-Tropsch wax into high quality synthetic crude or finished transportation fuels such as premium diesel has been studied over the past 15 years within BP. Catalyst screening and selection was carried out in dedicated micro-reactors and pilot plants, whose designs are critical to the performance selection. Variation in catalyst composition and defining the gas to oil feed ratios with the operating temperature are a few of the parameters studied. Product selection and maximizing diesel yield combined with stability （catalyst life） were the ultimate drivers. The selected catalyst was then tested under commercial conditions in a dedicated 300 barrel per day demonstration plant. The products were also tested in engines to assess their combustion characteristics.

关键词： Fischer-Tropsch wax upgrading hydrocracking synthetic crude diesel naphtha engine emission

SCENIC HUDSON'S LONG DOCK PARK CULTIVATING RESILIENCE:TRANSFORMING A POST-INDUSTRIAL BROWNFIELD INTO A FUNCTIONAL ECOSYSTEM

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Journal of Green Building 2016年第3期11卷 55-77页

作者： Chris Moyles Timothy Craul Reed Hilderbrand LLC Craul Land Scientists Inc

Scenic Hudson’s Long Dock Park is a resilient living work of art and a vibrant community asset for the Hudson River Valley.A 23-acre peninsula on the east side of the Hudson at Beacon,New York,the site includes the Peter *** Park and the Klara Sauer Hudson River *** decades in the making,beginning in 1997,it took a decade to plan and remediate,and,by its completion in early 2017,it will have taken just as long to build and *** 1997,nonprofit Scenic Hudson,the largest environmental and land preservation group focused on the Hudson River Valley,started assembling the different ownership parcels of the Long Dock *** 1999 to 2003,they engaged the Beacon community through a series of community meetings and workshops to articulate its vision for its waterfront and cleanup of the site *** 2003 to 2007,the design team developed the architectural and site program for the project,restoration measures,and its physical expression with the *** with the City and the New York State Department of Environmental Conservation(NYSDEC),the project completed the State Environmental Quality Review Act(SEQR)process,filing a Draft Environmental Impact Statement(DEIS)and received approval of the final EIS ensuring that there was significant environmental,social,or economic *** NYSDEC and the *** Corps of Engineers(USACE)were also directly involved in oversight of the brownfield remediation and work within the Hudson River and site *** the SEQR process complete and approval of a mitigation plan from the USACE,the team worked with the City of Beacon to complete the site plan application process for *** mandate was clear from the start-build resilience,but realize it *** project’s first phase,opened in 2009,included additional remediation and removal of contaminated soils,removal of invasive species,stabilization of the south shoreline,a test plot for different materials,a wetland boardwalk and interior pat

关键词： waterfront park brownfield remediation sustainable SITES designing soil for the urban environment stormwater treatment invasive plant species

Major Technologies for Safe Construction of High Earth-Rockfill Dams

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Engineering 2016年第4期2卷 498-509页

作者： Hongqi Ma Fudong Chi Huaneng Lancang River Hydropower inc. Kunming 650214 China

The earth-rockfill dam is one of the primary dam types in the selection of high dams to be constructed in Western China, since it is characterized by favorable adaptability of the dam foundation; full utilization of local earth, rock, and building-excavated materials; low construction cost; and low cement consumption. Many major technical issues regarding earth-rockfill dams with a height of over 250 m were studied and solved successfully in the construction of the 261.5 m Nuozhadu earth core rockfill dam. This paper describes research achievements and basic conclusions; systematically summarizes the accumulated experiences from the construction of the Nuozhadu Dam and other high earth-rockfill dams; and discusses major technical issues, such as deformation control, seepage control, dam slope stability, safety and control of flood discharging, safety and quality control of dam construction, safety assessments, early warning, and other key technical difficulties. This study also provides a reference and technological support for the future construction of 300 m high earth-rockfill dams.

关键词： High earth-rockfill dam Safe construction Major technologies

Corrosion Study of Base Material and Welds of a Ni-Cr-Mo-W Alloy

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Acta Metallurgica Sinica(English Letters) 2017年第4期30卷 326-332页

作者： Ajit Mishra Haynes International Inc. 1020 West Park AvenueKokomo IN 46904 USA

Alloys containing chromium （Cr） and molybdenum （Mo）, as the major alloying elements, are widely used in various industries where the material experiences corrosive environments. Chromium （Cr）, when added in an optimum amount, forms a Cr203 passive film which protects the underlying metal in aggressive solutions. Molybdenum （Mo） forms its oxides in the low pH solutions, thus, enhances the uniform corrosion resistance of an alloy in reducing acids and assists in inhibition to localized corrosion. Minor alloying elements, like tungsten （W） and copper （Cu）, also improve the overall corrosion resistance of an alloy in specific solutions. In the present study, corrosion resistance behavior of commercial iron- based alloys （316L SS, 254 SMO and 20Cb3） and nickel-based alloys （Mone1400, Alloy 625 and C-276） was studied in the acidic solutions. While the corrosion behavior of wrought alloys has been widely studied, there is little to no information on the corrosion performance of their welds, typically being the weak regions for corrosion initiation and propagation. Therefore, an attempt was undertaken to investigate the uniform and localized corrosion performance of base metal, simulated heat-affected zone and all-weld-metal samples of a Ni-Cr-Mo-W alloy, C-276. The study was conducted in aggressive acidic solutions. Various corrosion and surface analytical techniques were utilized to analyze the results.

关键词： Iron-chromium-molybdenum Nickel-chromium-molybdenum-tungsten All-weld-metal Heat-affected-zone Acids Acidified ferric chloride Potentiodynamic Scanning electronmicroscopy (SEM)

Effects of Microstructure on the Tensile, Fracture Toughness and Fatigue Behaviour of Gamma Titanium Aluminides

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Journal of Materials Science & Technology 1994年第2期10卷 79-91页

作者： Young- Won (Y-W.) Kim(UES, inc., Materials Research Division, 4401 Dayton-Xenia Rd., Dayton, OH 45432, USA)(Paper presented at the International Workshop on OrderedIntermetallics 1992, Hangzhou, China) USE Inc. Materials Research Division Dayton United States

The effects of microstructure on the deformation and fracture behaviour of two-phase TiAl alloys were investjgated under monotonic and cyclical loading conditions, over a range of temperatu *** tensile behaviour is analyzed for deformation temperatures between RT and 950℃, Fracture resistance behaviour and toughening mechanisms at RT and 800℃ are analyzed. and the inverse relationship botween ductility and toughness is explained using the crack initiation toughness. The preliminary results of load-controlled fatigue behaviour at 800℃ are interpreted using the tensile behaviour because deformation structure and fracture modes are similar under these two loading conditions

关键词： MPa Fracture Toughness and Fatigue Behaviour of Gamma Titanium Aluminides Effects of Microstructure on the Tensile OM

Event-based optimization with random packet dropping

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Science China(Information Sciences) 2020年第11期63卷 175-194页

作者： Qing-Shan JIA Jing-Xian TANG Zhenning LANG Center for Intelligent and Networked Systems Department of AutomationTsinghua University NetEase inc.

Event-based optimization(EBO) provides a general framework for policy optimization in many discrete event dynamic systems where decision making is triggered by events that represent state transitions with common features. Because the number of events can be defined by the user and usually increases linearly with respect to the system scale, EBO has good potential to address large-scale problems where the state space grows exponentially. However, in many practical systems, sensors are geographically distributed and connected to a central controller through imperfect communication channels. Therefore, events observed by the sensors may not reach the controller. Optimization methods of event-based policies in these cases have not yet been identified. In this paper, we consider this important problem and make three major contributions. First, we formulate a mathematical EBO model in which the communication between sensors and controllers is subject to random packet dropping. Second, we show that this EBO model can be converted to another EBO model with perfect communication. Then, the performance difference equation and the performance derivative equation for event-based policies are straightforward to develop. One gradient-based policy iteration algorithm is developed for problems where the state transition probabilities are explicitly known, while another for problems where they are unknown. Third, the performance of the algorithms and the impact of the packet dropping probability on policy performance are numerically demonstrated on a single-zone occupant level estimation problem in buildings.

关键词： event-based optimization packet dropping discrete event dynamic systems

Robust model selection for positive and unlabeled learning with constraints

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Science China(Information Sciences) 2022年第11期65卷 94-106页

作者： Tong WEI Hai WANG Weiwei TU Yufeng LI Department of Computer Science and Technology Nanjing University 4Paradigm inc.

Positive and unlabeled(PU) learning is the problem in which training data contains only PU samples. Although PU learning is widely used in real-world applications, its model selection remains challenging. Specifically, traditional model selection methods are often highly sensitive to the class prior as well as the data size, resulting in human overhead in hyperparameter optimization. In this paper, we present a method called ODE(robust model selection) for robust model selection in PU learning. Two novel model evaluators based on the integral probability metric and area under the curve, which are free of the class prior, are introduced, and a variance reduction method is further employed to improve the quality of model selection. In addition, we perform model selection under user-defined constraints and propose a fast halvingstyle searching algorithm to efficiently identify the most promising model configuration. Extensive empirical studies demonstrate that our proposed method performs more robustly and is more computationally efficient than many state-of-the-art methods.

关键词： positive and unlabeled learning model selection automated machine learning

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