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Correcting distortions of thin-walled machined parts by machine hammer peening

Chinese Journal of Aeronautics 2024年第6期37卷 439-453页

作者： Aitor MADARIAGA Mikel CUESTA Gorka ORTIZ-DE-ZARATE Eneko SAENZ-DE-ARGANDONA Denis SORIANO michael b.PRIME Pedro Jose ARRAZOLA Department of Materials University of ManchesterOxford RoadManchester M139PLUnited Kingdom Mechanical and Industrial Production Department Faculty of EngineeringMondragon UnibertsitateaArrasate 20500Spain Los Alamos National Laboratory Los AlamosNew MexicoUSA

Thin-walled aerostructural components frequently get distorted after the machining *** to correct distortions or eventually rejecting parts significantly increases the *** paper proposes a new approach to correct distortions in thin-walled components by strategically applying hammer peening on target surfaces of a machined *** alloy 7475-T7351 was chosen for this *** study was divided in two ***,the residual stresses(RS)induced by four different pneumatic hammer peening conditions(modifying the stepover distance and initial offset)were characterised in a test coupon,and one of the conditions was selected for the next *** the second stage,a FEM model was used to predict distortions caused by machining in a representative ***,the RS induced by hammer peening were included in an FEM model to define two hammer peening strategies(varying the coverage area)to analyse the capability to reduce *** workpieces were machined and then treated with the simulated hammer peening strategies for experimental *** in the test coupon showed that pneumatic hammer peening can generate high compressive RS(-50 to350 MPa)up to 800 lm depth,with their magnitude increasing with a reduced stepover *** of hammer peening over 4% of the surface of the representative workpiece reduced the machininginduced distortions by 37%,and a coverage area of 100% led to and overcorrection by a factor of *** confirms that hammer peening can be strategically applied(in target areas and changing the percentage of coverage)to correct low or severe distortions.

关键词： Aeronautics Machining,Hammer Peening Aluminium alloy Distortions Residual Stress

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Modelling the development of biological structures displaying longitudinal geometries in vitro:culturing pluripotent stem cells on plasma-treated,growth factor-coupled polycaprolactone fibres

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Engineered Regeneration 2024年第1期5卷 124-138页

作者： badwi b.boumelhem Stuart T.Fraser Syamak Farajikhah Rachel A.Shparberg michael b.Morris Marcela M.M.bilek Anyu Zhang behnam Akhavan Simon Fleming Maryanne Large School of Physics Faculty of ScienceUniversity of SydneyAustralia Sydney Nano Institute University of SydneyAustralia School of Chemical and biomolecular Engineering University of SydneyAustralia School of Medical Sciences Faculty of Medicine and HealthUniversity of SydneyAustralia School of biomedical Engineering Faculty of EngineeringUniversity of SydneyAustralia School of Engineering University of NewcastleCallaghanNSW 2308Australia Hunter Medical Research Institute(HMRI) Precision Medicine ProgramNew Lambton Heights NSW 2305Australia

Many biological structures such as nerves,blood and lymphatic vessels,and muscle fibres exhibit longitudinal ge-ometries with distinct cell types extending along both the length and width of internal linear *** these three-dimensional structures in vitro is challenging:the best-defined stem-cell differentiation systems are mono-layer cultures or organoids using pluripotent stem *** stem cells can differentiate into functionally mature cells depending on the signals received,holding great promise for regenerative ***,the integration of in vitro differentiated cell types into diseased tissue remains a *** scaffolds can bridge this gap if the appropriate signalling systems are incorporated into the ***,we have taken a biomimicry approach to generate longitudinal structures in *** this approach,mouse embryonic stem cells are directed to differentiate to specific cell types on the surface of polycaprolactone(PCL)fibres treated by plasma-immersion ion implantation and to which with lineage-specifying molecules have been covalently *** demonstrate the simplicity and utility of our method for efficiently generating high yields of the following cell types from these pluripotent stem cells:neurons,vascular endothelial cells,osteoclasts,adipocytes,and cells of the erythroid,myeloid,and lymphoid *** arranged plasma-treated scaffolds with differentiated cell types could ultimately serve as a means for the repair or treatment of diseased or damaged tissue.

关键词： Pluripotent stem cells Lineage commitment Growth factors biomaterial engineering Plasma-immersion ion implantation Covalent biomolecule attachment Polycaprolactone

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Near-Surface Soil Chemical Properties as Affected by Cover Crops Over Time in the Lower Mississippi River Valley

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Agricultural Sciences 2024年第9期15卷 1035-1056页

作者： Cooper Fanning Kristofor R. brye michael b. Daniels Trenton L. Roberts Samuel Fernandes Lisa S. Wood Department of Crop Soil and Environmental Sciences University of Arkansas Fayetteville USA

Typical row-crop agricultural practices can potentially be harmful to soil health and future sustainability. The use of cover crops (CC) as a mechanism to improve soil health on a wide scale remains underutilized. Soil health remains a major concern for the sustainability of agricultural productivity, therefore, research into CC implementation as a mean to preserve or improve soil health is warranted. The objective of this study was to evaluate the effects of CC on the soils in the eastern Arkansas portion of the Lower Mississippi River Valley (LMRV) over time for various chemical soil parameters, including pH, soil organic matter (SOM), soil elemental contents (i.e., P, K, Ca, Mg, S, Na, Fe, Mn, Zn, Cu, and b), soil respiration, and a generalized soil health score index. Soil pH decreased over time under both CC and no-cover-crop (NCC) treatments, by −0.3 and −0.2, respectively. Soil OM decreased over time under NCC by −0.1%, but did not differ between CC treatments. Soil N availability decreased over time under NCC (−22.6 kg·ha−1), but did not change over time under CC. Soil respiration decreased over time under both CC and NCC, by −76.1 mg·L−1 and −77.3 mg·L−1, respectively, though there was no effect of CC treatment. The Haney soil health score index decreased under CC (−7.0) and NCC (−6.8) without an effect from CC treatment. Results of the study place emphasis on the temporal nature of soil health as influenced by cover crops and their potential to improve soil health.

关键词： Arkansas Cover Crops Soil Properties Soil Organic Matter Soil Health Score

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Challenge of global climate change:Prospects for a new energy paradigm

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Frontiers of Environmental Science & Engineering 2010年第1期4卷 2-11页

作者： michael b.MCELROY School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences Harvard UniversityCambridgeMA 02138USA

Perspectives on the challenge posed by potential future climate change are presented including a discussion of prospects for carbon capture followed either by sequestration or reuse including opportunities for alternatives to the use of oil in the transportation *** potential for wind energy as an alternative to fossil fuel energy as a source of electricity is outlined including the related opportunities for cost effective curtailment of future growth in emissions of CO_(2).

关键词： climate change carbon capture wind ethanol CO_(2) radiative forcing

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Does foraging mode affect metabolic responses to feeding？ A study of pygopodid lizards

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Current Zoology 2013年第5期59卷 618-625页

作者： michael WALL michael b. THOMPSON Richard SHINE School of biological Sciences A08 University of Sydney NSW 2006 Australia Current address: 4940 Anza St. #4 San Francisco CA 94121 USA

Foraging mode （ambush vs. active） profoundly affects many aspects of organismal biology, including metabolic rates and their relationship with food intake. Previous studies on snakes suggest that ambushers tend to have lower standard metabolic rates （SMR） and higher energetic costs of digestion and assimilation of prey （specific dynamic action, or SDA） than do active foragers. However, phylogenetic considerations may be at least partly responsible for such patterns, as foraging mode is strongly conserved evolutionarily and most SDA studies have focused on species from only two lineages of ambush foragers （pythonid and viperid snakes） and one lineage of active foragers （colubrid snakes）. We sought to deconfound the effects of phylogeny and foraging mode, investigating SMR and SDA in two closely related pygopodid lizards, the common scaly-foot Pygopus lepidopo- dus （active forager） and burton＇s legless lizard Lialis burtonis （ambush forager）. Consistent with the pattern seen in snakes, L. burtonis exhibits a significantly lower SMR and a higher SDA than does P lepidopodus. The magnitude of SDA in L. burtonis is comparable to that of some pythons and vipers, providing yet more evidence for the remarkable convergence between this species and ambush-foraging snakes [Current Zoology 59 （5）： 618-625, 2013].

关键词： Ecology Metabolic rates Reptile Specific dynamic action

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羽毛的演化艺术

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环球科学 2024年第17期 44-53页

作者：迈克尔·b.哈比卜邓以琳(翻译) 胡晗(审校) 美国洛杉矶自然历史博物馆大洛杉矶动物园协会中山大学生态学院中国科学院古脊椎动物与古人类研究所

2022年10月,一只编号为b6的鸟创造了一项全新的世界纪录。然而,这项纪录在鸟类学界之外却鲜为人知。11天内,b6这只年轻的斑尾滕(Limosa lapponica)连续飞行超过1.3万千米,从它在美国阿拉斯加州的繁殖地,一直飞到澳大利亚塔斯马尼亚州的... 详细信息

2022年10月,一只编号为b6的鸟创造了一项全新的世界纪录。然而,这项纪录在鸟类学界之外却鲜为人知。11天内,b6这只年轻的斑尾滕(Limosa lapponica)连续飞行超过1.3万千米,从它在美国阿拉斯加州的繁殖地,一直飞到澳大利亚塔斯马尼亚州的越冬地.

关键词：越冬地繁殖地斑尾世界纪录澳大利亚

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Diagnostic approach to patients with acute idiopathic and recurrent pancreatitis,what should be done?

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World Journal of Gastroenterology 2008年第7期14卷 1007-1010页

作者： Mohammad Al-Haddad michael b Wallace Division of Gastroenterology and Hepatology Mayo Clinic College of MedicineJacksonvilleFL 32224United States

Acute recurrent pancreatitis (ARP) is a common clinical condition that may be difficult to diagnose. Endoscopic ultrasound (EUS) is proposed to be a safe first line test of choice in the majority of patients. When interventions are needed to remove biliary stones, evaluate sphincter of Oddi or pancreas divisum, endoscopic retrograde cholangiopancreatography (ERCP) is recommended. Magnetic resonance cholangiopancreatography (MRCP) can be a suitable alternative from a diagnostic standpoint although may not be widely available. Finally, genetic testing is increasingly used to detect certain mutations that are associated with this diagnosis.

关键词： Acute recurrent pancreatitis Idiopathic pancreatitis Endoscopic ultrasound Endoscopic retrograde cholangiopancreatography Magnetic resonance cholangiopancreatography

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Wind and Solar Power in the United States:Status and Prospects

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CSEE Journal of Power and Energy Systems 2017年第1期3卷 1-6页

作者： michael b McElroy Xinyu Chen Join A.Paulson School of Engineering and Applied Sciences Harvard UniversityCambridgeMA02138USA

The United States has committed to reduce its greenhouse gas emissions by 26%–28%by 2025 and by 83%by 2050 relative to *** these objectives will require major investments in renewable energy options,particularly wind and *** investments are promoted at the federal level by a variety of tax credits,and at the state level by requirements for utilities to include specific fractions of renewable energy in their portfolios(Renewable Portfolio Standards)and by opportunities for rooftop PV systems to transfer excess power to utilities through net metering,allowing meters to operate in *** paper discusses the current status of these incentives.

关键词： Incentives net metering renewable energy renewable energy portfolio

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Interactions of primary insult biomechanics and secondary cascades in spinal cord injury： implications for therapy

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Neural Regeneration Research 2017年第10期12卷 1618-1619页

作者： michael b.Orr John C.Gensel Spinal Cord and brain Injury Research Center and the Department of Physiology the University of KentuckyLexingtonKYUSA Integrated biomedical Sciences Graduate Program the University of KentuckyLexingtonKYUSA

The complex and variable nature of traumatic spinal cord inju- ry （SCI） presents a unique challenge for translational research. SCI is not bound by any demographic nor is it limited to specific injury biomechanics.

关键词： SCI Interactions of primary insult biomechanics and secondary cascades in spinal cord injury:implications for therapy

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Mechanisms of Organelle Inheritance in Dividing Plant Cells

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Journal of Integrative Plant biology 2007年第8期49卷 1208-1218页

作者： michael b Sheahan Ray J Rose David W McCurdy School of Environmental and Life Sciences The University of NewcastleCallaghan NSW 2308Australia Australian Research Council Centre of Excellence for Integrative Legume ResearchSchool of Environmental and Life SciencesThe University of NewcastleCallaghan NSW 2308Australia School of Environmental and Life Sciences The University of NewcastleCallaghan NSW 2308Australia

Organelles form essential compartments of all eukaryotic cells. Mechanisms that ensure the unbiased inheritance of organelles during cell division are therefore necessary to maintain the viability of future cell generations. Although inheritance of organelles represents a fundamental component of the cell cycle, surprisingly little is known about the underlying mechanisms that facilitate unbiased organelle inheritance. Evidence from a select number of studies, however, indicates that ordered organelle inheritance strategies exist in dividing cells of higher plants. The basic requirement for unbiased organelle inheritance is the duplication of organelle volume and distribution of the resulting organelle populations in a manner that facilitates unbiased partitioning of the organelle population to each daughter cell. Often, partitioning strategies are specific to the organelle, being influenced by the functional requirements of the organelle and whether the cells are mitotically active or re-entering into the cell cycle. Organelle partitioning mechanisms frequently depend on interactions with either the actin or microtubule cytoskeleton. In this focused review, we attempt to summarize key findings regarding organelle partitioning strategies in dividing cells of higher plants. We particularly concentrate on the role of the cytoskeleton in mediating unbiased organelle partitioning.

关键词： Actin cytoskeleton cell division green fluorescent protein-fimbrin AbD2 organelle partitioning protoplast

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