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Convolutional neural network-assisted recognition of nanoscale L1_(2) ordered structures in face-centred cubic alloys

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npj Computational Materials 2021年第1期7卷 60-68页

作者： Yue Li Xuyang Zhou timoteo Colnaghi Ye Wei Andreas Marek Hongxiang Li Stefan Bauer Markus Rampp leigh t.stephenson Max-Planck Institut für Eisenforschung GmbH Max-Planck-Straße 140237 DüsseldorfGermany Max Planck Computing and Data Facility Gießenbachstraße 285748 GarchingGermany State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing100083 BeijingChina Max Planck Institute for Intelligent Systems Max-Planck-Ring 472076 TübingenGermany

Nanoscale L12-type ordered structures are widely used in face-centered cubic(FCC)alloys to exploit their hardening capacity and thereby improve mechanical *** fine-scale particles are typically fully coherent with matrix with the same atomic configuration disregarding chemical species,which makes them challenging to be *** distribution maps(SDMs)are used to probe local order by interrogating the three-dimensional(3D)distribution of atoms within reconstructed atom probe tomography(APt)***,it is almost impossible to manually analyze the complete point cloud(>10 million)in search for the partial crystallographic information retained within the ***,we proposed an intelligent L1_(2)-ordered structure recognition method based on convolutional neural networks(CNNs).the SDMs of a simulated L1_(2)-ordered structure and the FCC matrix were firstly *** simulated images combined with a small amount of experimental data were used to train a CNN-based L1_(2)-ordered structure recognition ***,the approach was successfully applied to reveal the 3D distribution of L1_(2)–typeδ′–Al3(LiMg)nanoparticles with an average radius of 2.54 nm in a FCC Al-Li-Mg *** minimum radius of detectable nanodomain is even down to 5Å.the proposed CNN-APt method is promising to be extended to recognize other nanoscale ordered structures and even more-challenging short-range ordered phenomena in the near future.

关键词： alloys ordered cubic

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the role of Ca,Al and Zn on room temperature ductility and grain boundary cohesion of magnesium

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Journal of Magnesium and Alloys 2021年第5期9卷 1536-1551页

作者： Supriya Nandy Shao-Pu tsai leigh stephenson Dierk Raabe Stefan Zaefferer Max-Planck Institut für Eisenforschung Düsseldorf 40237Germany

It is know from literature that small additions(<1 wt%)of Ca,Al and Zn significantly improve the intrinsic ductility of *** exact role of each element,both qualitatively and quantitatively,and their combined effects,h... 详细信息

It is know from literature that small additions(t%)of Ca,Al and Zn significantly improve the intrinsic ductility of *** exact role of each element,both qualitatively and quantitatively,and their combined effects,however,are poorly *** we achieved a much clearer view on the quantitative role of each element with respect to ductility improvement and on the collaborative effect,particularly of Ca and Zn in *** of our findings and conclusions are in disagreement with data and interpretation found in *** different alloys,namely,Mg-0.1 Ca,Mg-0.1 Ca-1 Al,Mg-0.05 Ca-1 Al,Mg-0.1 Ca-2 Al-1 Zn(all are in wt%)were selected for this *** alloys were treated such that *** grain sizes and textures were *** largely excludes the effect of extrinsic factors on ***-guided slip trace analyses reveal that the addition of Ca eases activation of prismatic and pyramidal II slip *** in-situ deformation experiments in SEM and atom probe tomography observations of grain boundaries direct evidence is given for the individual and synergetic effects of Ca and Zn on grain boundary cohesion as an important contribution to improve the ductility of these *** conclude that Ca reduces the slip anisotropy and ameliorates ductility,however,the weak grain boundary cohesion in the Mg-0.1 wt%Ca alloy limits the material’s tensile *** addition of Zn alters the Ca segregation at the grain boundaries and helps to retain their cohesive strength,an effect which thus enables higher ductility and *** further addition of Al primarily improves the *** results show that the balanced influence of reduced slip anisotropy on the one hand and increased grain boundary cohesion on the other hand allow to design a high strength high ductility rare-earth free Mg alloy.

关键词： Magnesium–Calcium–Zinc alloys Ductility Slip system determination grain boundary cohesion

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Properties of diamond tool binders with fine carbonyl Ni powder additions

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金刚石与磨料磨具工程 2008年第S1期28卷 148-151页

作者： stephenson t F Korotkin M Metcalfe S 2060 Hadwen Road Mississauga Ontario L5K 1Z9 Canada

Fine Ni powder is often added to Co and bronze-based metal binder powders for diamond tool *** is a lower cost substitute for extra-fine Co powder and increases the toughness of Co-Fe diamond binders at the expense of lower hardness and bend *** bronze-based diamond binder segments,Ni increases hardness and yield *** grades of Ni powder are used commercially with both Co and bronze-based diamond *** paper compares properties of diamond binders containing carbonyl Ni powders including standard Inco(?) t255,t123 PM and t 110 *** materials were made by ball milling or dry mixing of the fine carbonyl Ni and Fe powders with either XF Co or air atomized bronze(90/10 Cu/Sn) ***-based powder blends were hot pressed at 20～35 MPa and 700℃to 900℃.Bronze-based powder blends were cold pressed and sintered at 840℃.Apparent density,apparent hardness and bend strength(tRS) were compared for different binder compositions and processing conditions.

关键词： binder Ni powder additive diamond tool

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Development of a brownfield inventory for prioritizing funding outreach in tucson,Arizona

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Geo-Spatial Information Science 2021年第4期24卷 742-754页

作者： theresa Foley Ann Marie Wolf Chloe Jackson Ryan stephenson Sonora Environmental Research Institute Inc.(SERI)TucsonAZUSA Pima County ItD/GIS TucsonAZUSA Pima County Community Development&Neighborhood Conservation TucsonAZUS

Fear of liability from the 1980 Comprehensive Environmental Response,Compensation,and Liability Act(CERCLA or Superfund)has prompted developers to build preferentially upon undeveloped green space rather than potentially contaminated former industrial sites,leading to urban sprawl in the suburban areas while blighted properties in the urban core remain vacant.A brownfield is defined as a property in which the presence or potential presence of a hazardous substance or contaminant poses a barrier to *** often create brownfield inventories by performing a site suitability analysis,using distinguishing features such as ecolo-gically and culturally significant areas or neighborhoods that need *** County,Arizona and the Sonora Environmental Research Institute,Inc.(SERI)developed a brownfield inventory of the large,industrial area directly to the west of Davis-Monthan Air Force *** the brownfield target area has few residential neighborhoods and lacks the distinguish-ing features usually used in a brownfield site suitability analysis,the county and SERI used the official tax assessor database and 11 federal,state and county environmental databases to develop a brownfield *** goal of the project was to prioritize properties that stood to benefit from the grant *** final brownfield inventory contained 531 parcels.

关键词： GIS site suitability analysis brownfield urban planning brownfield inventory

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False codling moth thaumatotibia leucotreta （Lepidoptera, tortricidae） larvae are chill-susceptible

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Insect Science 2012年第3期19卷 315-328页

作者： leigh Boardman tim G. Grout John S. terblanche Department of Conservation Ecology and Entomology Faculty of Agrisciences Stellenbosch University Stellenbosch South Africa Citrus Research International Nelspruit South Africa

this study reports on the low temperature tolerance and cold hardiness of larvae of false codling moth, thaumatotibia leucotreta. We found that larvae have mean critical thermal minima （lower limits of activity） of 6.7℃ which was influenced by feeding status. the effects of low temperature exposure and duration of exposure on larval survival were assessed and showed that the temperature at which 50% of the population survives is -11.5 ± 0.3℃ after 2 h exposure. the supercooling point （SCP, i.e., freezing temperature） was investigated using a range of cooling rates and under different conditions （feeding and hydration status） and using inoculative freezing treatments （in contact with water or orange juice）. the SCP decreased significantly from -15.6℃ to -17.4℃ after larvae were fasted for 24 h. twenty-four hour treatments at either high or low relative humidity （95.9% or 2.4%） also significantly decreased SCP to -17.2℃ and -18.2℃ respectively. Inoculative freezing （by water contact） raised SCP from -15.6℃ to -6.8℃ which could have important implications for post-harvest sterilization. Cooling rates did not affect SCP which suggests that there is limited phenotypic plasticity of SCP during the larval life-stage, at least over the short time-scales investigated here. In conclusion, larvae of t. leucotreta are chill-susceptible and die upon freezing. these results are important in understanding this pest＇s response to temperature variation, understanding pest risk status and improving post-harvest sterilization efficacy

关键词： behavior chill injury cold hardiness disinfestations extracellular freezing,lethal limits life-stage

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Restoration of the Western Himalaya： implications for metamorphic protoliths, thrust and normal faulting, and channel flow models

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Episodes 2007年第4期30卷 242-257页

作者： Michael P. Searle Ben stephenson James Walker Christian Walker Dept. Earth Sciences Oxford University Parks Road Oxford OX1 3PR UK Shell Canada Energy 400 - 4th Ave. SW Calgary Alberta T2P 2H5 Canada Imperial Oil Resources ExxonMobil 237 4th Ave. SW Calgary Alberta T2P 3M9 Canada CHP Consulting London EC2N 2HA UK

the Greater Himalayan Sequence （GHS） is composed of a sequence of Barrovianfacies metamorphic rocks up to kyanite or sillimanite ＋ K-feldspar grade, migmatites, layered stromatic migmatites and leucogranite sheets. these rocks were metamorphosed during the late Eocene to early Miocene, and are bounded below by a large-scale SW-vergent ductile shear zone-thrust fault （Main Central thrust; MCt）, and above by a NE-dipping low-angle normal sense shear zone and fault （Zanskar Shear Zone; ZSZ）,

关键词：变形原岩喜玛拉雅山断层作用地质模型

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Design Optimization of a Micro-Combustor for Lean, Premixed Fuel-Air Mixtures

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Journal of Power and Energy Engineering 2016年第6期4卷 13-26页

作者： leigh t. Powell Ralph C. Aldredge Department of Mechanical and Aerospace Engineering University of California-Davis Davis CA USA

Present technology has been shifting towards miniaturization of devices for energy production for portable electronics. Micro-combustors, when incorporated into a micro-power generation system, create the energy desired in the form of hot gases to power such technology. this creates the need for a design optimization of the micro-combustor in terms of geometry, fuel choice, and material selection. A total of five micro-combustor geometries, three fuels, and three materials were computationally simulated in different configurations in order to determine the optimal micro-combustor design for highest efficiency. Inlet velocity, equivalence ratio, and wall heat transfer coefficient were varied in order to test a comprehensive range of micro-combustor parameters. All simulations completed for the optimization study used ANSYS Fluent v16.1 and post-processing of the data was done in CFD Post v16.1. It was found that for lean, premixed fuel-air mixtures (φ= 0.6 - 0.9) ethane (C2H6) provided the highest flame temperatures when ignited within the micro-combustor geometries. An aluminum oxide converging micro-combustor burning ethane and air at an equivalence ratio of 0.9, an inlet velocity of 0.5 m/s, and heat transfer coefficient of 5 W/m2-K was found to produce the highest combustor efficiency, making it the optimal choice for a micro-combustor design. It is proposed that this geometry be experimentally and computationally investigated further in order to determine if additional optimization can be achieved.

关键词： Micro-Combustor Combustion Computational Fluid Dynamics Ethane Efficiency

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A Speculation: Avian Migration and the K-t Extinction

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Natural Resources 2024年第5期15卷 125-129页

作者： Laurence stephenson Association of Professional Engineers and Geologists of British Columbia Vancouver Canada

One caveat to the dinosaur’s extinction is the conclusion that avian dinosaurs survived and became ancestors of birds. their mobility enabled them to migrate great distances and find the nutrients needed to survive. Given this scenario, could the current observable migration of birds (the “dinosaurian offspring”) now be related? Migration is the regular seasonal movement undertaken by many species of birds, with the most common pattern, flying north in the Northern spring to breed in the temperate or Arctic summer and returning in the Northern autumn to wintering grounds in warmer regions of the south. the primary motivation for migration appears to be food. None of the major North-South migratory pathways fly over the Caribbean but three main fly ways, past to the west of the theorized K-t impact centre. Due to their ability to fly, the “avian Dinosaurs” adapted and survived very quickly in response to the disaster that marked the K-t boundary. It is an interesting speculation that the avian migration that we witness today is rooted in an event that occurred 66 million years ago! But it does explain why the migratory birds mostly fly from Polar summer to polar summer when they could just be as easily fly from Polar zone to the warmer equatorial region and back. In the recent article in Nature by Melanie During about identifying the late spring timing of the “Astro disaster”, it can be cited as consistent with my speculation. A late April early May Impact as suggested by During would have seen these migrations completely. the western migratory routes would have been found to be “luxurious” in vegetation in that first northern autumn after the “Astro-impact” while all eastern routes would have still been barren.

关键词： Dinosaur Clades K-t Mass Extinction Avian Migration Migratory Pathways Avian Dinosaurs K-t Impact Centre

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Final anatomic and visual outcomes appear independent of duration of silicone oil intraocular tamponade in complex retinal detachment surgery

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International Journal of Ophthalmology(English edition) 2018年第1期11卷 83-88页

作者： Maedbh Rhatigan Elizabeth Mc Elnea Patrick Murtagh Kirk stephenson Elaine Harris Paul Connell David Keegan Department of Ophthalmology Mater Misericordiae University Hospital

AIM： to report anatomic and visual outcomes following silicone oil removal in a cohort of patients with complex retinal detachment, to determine association between duration of tamponade and outcomes and to compare patients with oil removed and those with oil in situ in terms of demographic, surgical and visual factors. MEtHODS： We reported a four years retrospective case series of 143 patients with complex retinal detachments who underwent intraocular silicone oil tamponade. Analysis between anatomic and visual outcomes, baseline demographics, duration of tamponade and number of surgical procedures were carried out using Fisher＇s exact test and unpaired two-tailed t-test. RESULtS： One hundred and six patients（76.2%） had undergone silicone oil removal at the time of review with 96 patients（90.6%） showing retinal reattachment following oil removal. Duration of tamponade was not associated with final reattachment rate or with a deterioration in best corrected visual acuity（BCVA）. Patients with oil removed had a significantly better baseline and final BCVA compared to those under oil tamponade（P=0.0001, 〈0.0001 respectively）. CONCLUSION： Anatomic and visual outcomes in this cohort are in keeping with those reported in the literature. Favorable outcomes were seen with oil removal but duration of oil tamponade does not affect final attachment rate with modern surgical techniques and should be managed on a case by case basis.

关键词： silicone oil tamponade proliferative vitreoretinopathy retinal detachment

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Canadian children’s and youth’s adherence to the 24-h movement guidelines during the COVID-19 pandemic: A decision tree analysis

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Journal of Sport and Health Science 2020年第4期9卷 313-321页

作者： Michelle D.Guerrero leigh M.Vanderloo Ryan E.Rhodes Guy Faulkner Sarah A.Moore Mark S.tremblay Children’s Hospital of Eastern Ontario Research Institute OttawaON K1H 8L1Canada ParticipACtION TorontoON M5S 1M2Canada Child Health and Evaluative Sciences Hospital for Sick ChildrenTorontoON M5G 0A4Canada Behavioral Medicine Laboratory School of Exercise SciencePhysical and Health EducationUniversity of VictoriaVictoriaBC V8W 2Y2Canada School of Kinesiology University of British ColumbiaVancouverBC V6T 1Z1Canada Department of therapeutic Recreation Faculty of ChildFamilyand Community StudiesDouglas CollegeCoquitlamBC V3B 7X3Canada School of Health and Human Performance Dalhousie UniversityHalifaxNS B3H 4R2Canada Department of Pediatrics University of OttawaOttawaON K1H 8L1Canada

Purpose:the purpose of this study was to use decision tree modeling to generate profiles of children and youth who were more and less likely to meet the Canadian 24-h movement guidelines during the coronavirus disease-2019(COVID-19)***:Data for this study were from a nationally representative sample of 1472 Canadian parents(Meanage=45.12,SD=7.55)of children(511 years old)or youth(1217 years old).Data were collected in April 2020 via an online *** items assessed demographic,behavioral,social,micro-environmental,and macro-environmental *** decision trees of adherence and non-adherence to all movement recommendations combined and each individual movement recommendation(physical activity(PA),screen time,and sleep)were ***:Results revealed specific combinations of adherence and non-adherence *** associated with adherence to the recommendation(s)included high parental perceived capability to restrict screen time,annual household income ofCAD 100,000,increases in children’s and youth’s outdoor PA/sport since the COVID-19 outbreak began,being a boy,having parents younger than 43 years old,and small increases in children’s and youth’s sleep duration since the COVID-19 outbreak *** associated with non-adherence to the recommendation(s)included low parental perceived capability to restrict screen time,youth aged 1217 years,decreases in children’s and youth’s outdoor PA/sport since the COVID-19 outbreak began,primary residences located in all provinces except Quebec,low parental perceived capability to support children’s and youth’s sleep and PA,and annual household income ofCAD 99,***:Our results show that specific characteristics interact to contribute to(non)adherence to the movement behavior *** highlight the importance of targeting parents’perceived capability for the promotion of children’s and youth’s movement behaviors during challengin

关键词： Decision tree analysis Parental perceived capability Physical activity Screen time Sleep

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