检索结果-南通市图书馆

mICROSTRUCTURE AND mECHANICAL BEHAVIOR OF Nb-(10, 15)A1-20V ALLOYS

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English Letters) 2004年第4期17卷 575-583页

作者： H.S.Jiao F.Barradas T.S.Rong I.P.jones m.Aindow Department of metallurgy and materials University of Birmingham B15 2TT UKDepartment of Metallurgy and Materials University of Birmingham B15 2TT UKDepartment of Metallurgy and Materials University of Birmingham B15 2TT UKDepartment of Metallurgy and Materials University of Birmingham B15 2TT UKDepartment of Metallurgy and Materials Engineering Institute of Materials Science University of Connecticut CT 06269-3136 USA

Compression tests at room and high temperature and creep tests at high temperature have been performed on B2 Nb15A120V and Nb10Al20V alloys. At room temperature, in the as-cast state, both alloys exhibited significant ductility in compression. The Burgers vectors of the dislocations were found to be 1/2lipping on {112}. The dislocations showed good mobility. Dislocation clusters also triggered the formation of pseudotwins, which resulted in serrated yielding. In steady state creep, deformation occurred by a combination of dislocation glide and climb, giving a homogeneous mi-crostructure. The dislocations in NblOAl20V were determined to be 1/2(111) slipping on {110} with some egments. After creep at 1100℃, Nb 15A120V showed a two phase structure with a few dislocations in the A15 phase but no dislocations in the A2 phase.

关键词： dislocation pseudotwin NbAlV alloy creep

Fitness and physiology of Adelges tsugae （Hemiptera： Adelgidae） in relation to the health of the eastern hemlock

在线全文

学校读者我要写书评

暂无评论

Insect Science 2016年第6期23卷 843-853页

作者： Anne C. jones Donald E. mullins Carlyle Brewster James P. Rhea Scott m. Salom Department of Entomology Pennsylvania State University PA 16801 Department of Entomology Virginia Tech Blacksburg VA 24061 USDA Forest Service Asheville NC 28804-3454 USA

The hemlock woolly adelgid, Adelges tsugae Annand is an invasive insect that frequently causes hemlock （Tsuga spp.） mortality in the eastern United States. Studies have shown that once healthy hemlocks become infested by the adelgid, nutrients are depleted from the tree, leading to both tree decline and a reduction of the adelgid population. Since A. tsugae is dependent on hemlock for nutrients, feeding on trees in poor health may affect the ability of the insect to obtain necessary nutrients and may consequently affect their physiological and population health. Trees were categorized as lightly or moderately impacted by A. tsugae based on quantitative and qualitative tree health measurements. Population health ofA. tsugae on each tree was determined by measuring insect density and peak mean fecundity; A. tsugae physiological health was determined by measuring insect biomass, total carbon, carbohydrate, total nitrogen, and amino nitrogen levels. Adelges tsugae from moderately impacted trees exhibited significantly greater fecundity than from lightly impacted trees. However, A. tsugae from lightly impacted hemlocks contained significantly greater levels of carbohydrates, total nitrogen, and amino nitrogen. While the results of the physiological analysis generally support our hypothesis that A. tsugae on lightly impacted trees are healthier than those on moderately impacted trees, this was not reflected in the population health measurements. Adelges tsugae egg health in response to tree health should be verified. This study provides the first examination of A. tsugae physiological health in relation to standard A. tsugae population health measures on hemlocks of different health levels.

关键词： Adelges tsugae carbohydrates fecundity nitrogen tree health Tsuga canadensis

Analysis of Underlay Cognitive Radio Networks Based on Interference Cancellation mechanism

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, materials & Continua 2020年第4期63卷 401-416页

作者： Lei Wang Jian Liu Changming Zhao alan Yang School of Computer&Communication Engineering University of Science and Technology BeijingBeijing100083China School of Computer Science Chengdu University of Information TechnologyChengdu610225China College of Computer Science Sichuan UniversityChengdu610041China Amphenol Assemble Tech HoustonTX 77070USA

In this paper,we investigate the performance of secondary transmission scheme based on markov ON-OFF state of primary users in Underlay cognitive radio *** propose flexible secondary cooperative transmission schemewith interference cancellation technique according to the ON-OFF status of primary *** maximal ratio combining(mRC)at destination,we have derived exact closed-form expressions of the outage probability in different *** numerical simulation results also reveal that the proposed scheme improve the secondary transmission performance compared with traditional mechanism in terms of secondary outage probability and energy efficiency.

关键词： Cognitive radio markov ON-OFF state relay selection outage probability

Hazards from lakes and reservoirs: new interpretation of the Vaiont disaster

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of mountain Science 2022年第6期19卷 1717-1737页

作者： alan P.DYKES Edward N.BROmHEAD Centre for Engineering Environment and Society ResearchSchool of Engineering and the EnvironmentKingston UniversityPenrhyn RoadKingston upon ThamesKTi 2EEUK

Hazards in reservoirs and lakes arising from subaerial landslides causing impact waves(or ‘lake tsunamis’) are now well known, with several recent examples having been investigated in detail. The potential scale of such hazards was not widely known at the time of the Vaiont dam project in the 1950s and early 1960s, although a small wave triggered by a landslide at another new reservoir nearby in the Dolomites(northern Italy) drew the possible hazard to the attention of the Vaiont project’s managers. The Vaiont disaster in 1963 arose from a combination of disparate and seemingly unrelated factors and circumstances that led to an occurrence that could not have been imagined at that time. The ultimate cause was a very large landslide moving very rapidly into a reservoir and displacing the water. The resulting wave overtopped the dam to a height of around 175 m and around 2000 people were killed. This paper identifies and examines all of the issues surrounding the Vaiont dam and landslide in order to identify causal factors, contributory factors(including aggravating factors) and underlying factors. In doing so, it demonstrates that the disaster arose from the Vaiont dam project and cannot be attributed simply to the landslide. Underlying geological factors gave rise to the high speed of the landslide, which would have occurred anyway at some time. However, without the contributory factors that account for the presence of the reservoir, i.e. the choice of location for the project and management of the project with respect to a possible landslide hazard, there would have been no disaster. Indeed, the disaster could have been avoided if the reservoir could have been emptied pending further ground investigations. Understanding of this case provides many lessons for future dam projects in mountainous locations but also highlights an ongoing and perhaps under-appreciated risk from similar events involving other water bodies including geologically recent lakes formed behind n

关键词： Vaiont landslide Impulse wave Lake tsunami Dam project Causal factors for disaster

Cooperative Relay Selection mechanism in multi-Hop Networks

在线全文

学校读者我要写书评

暂无评论

Computers, materials & Continua 2020年第4期63卷 119-130页

作者： Jian Liu Lei Wang Changming Zhao alan Yang University of Science and Technology Beijing Beijing100083China School of Computer Science Chengdu University of Information TechnologyChengdu610225China College of Computer Science Sichuan UniversityChengdu610041China Amphenol Assemble Tech HoustonTX 77070USA

In this paper, we consider a three-hop relay system based on interference cancellation technique in Underlay cognitive radio (CR) network. Although underlay CR has been shown as a promising technique to better utilize the source of primary users (PUs), its secondary performance will be severely degraded. On one hand, by adapting the Underlay spectrum sharing pattern, secondary users (SUs) would observe the strict power constraints and be interfered by primary users. On the other hand, limited transmit power results in limited transmission range, which greatly degrade the secondary transmission capacity. To solve the problems above, we propose an interference cancellation protocol for multi-hop wireless communication networks in underlay CR, which could develop the long-distance transmission performance and improve the transmission efficiency significantly. As simulation results shows, proposed scheme significantly reduce the secondary outage probability and increase the secondary diversity than the traditional cases.

关键词： Cognitive relay networks interference cancellation power control secondary outage probability

Validation of the Rockall scoring system for outcomes from non-variceal upper gastrointestinal bleeding in a Canadian setting

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2006年第48期12卷 7779-7785页

作者： Robert A Enns Yves m Gagnon alan N Barkun David Armstrong Jamie C Gregor Richard N Fedorak RUGBE Investigators Group Division of Gastroenterology University of British Columbia Vancouver Canada Occam Research & Consulting Inc. VancouverCanada Department of medicine Division of Gastroenterology McGill University and the McGill UniversityHealth Center Montreal Canada Division of Gastroenterology McMaster University Medical Centre Hamilton Canada Division of Gastroenterology University of Western Ontario London Canada Division of Gastroenterology University of Alberta Edmonton Canada 不详

AIm: To validate the Rockall scoring system for predicting outcomes of rebleeding, and the need for a surgical procedure and death. mETHODS: We used data extracted from the Registry of Upper Gastrointestinal Bleeding and Endoscopy including information of 1869 patients with non-variceal upper gastrointestinal bleeding treated in Canadian hospitals. Risk scores were calculated and used to classify patients based on outcomes. For each outcome, we used χ2 goodness-of-fit tests to assess the degree of calibration, and built receiver operating characteristic curves and calculated the area under the curve (AUC) to evaluate the discriminative ability of the scoring system. RESULTS: For rebleeding, the χ2 goodness-of-fit test indicated an acceptable fit for the model [χ2 (8) = 12.83, P = 0.12]. For surgical procedures [χ2 (8) = 5.3, P = 0.73] and death [χ2 (8) = 3.78, P = 0.88], the tests showed solid correspondence between observed proportions and predicted probabilities. The AUC was 0.59 (95% CI: 0.55-0.62) for the outcome of rebleeding and 0.60 (95% CI: 0.54-0.67) for surgical procedures, representing apoor discriminative ability of the scoring system. For the outcome of death, the AUC was 0.73 (95% CI: 0.69-0.78), indicating an acceptable discriminative ability. CONCLUSION: The Rockall scoring system provides an acceptable tool to predict death, but performs poorly for endpoints of rebleeding and surgical procedures.

关键词： Upper gastrointestinal bleeding Nonvariceal Predictors Rockall Outcomes

A review of challenges and opportunities in micropillar compression studies in mg alloys

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of magnesium and Alloys 2023年第11期11卷 4043-4053页

作者： A.Kodam m.S.Gundi Y.L.Chiu I.P.jones S.S.Singh J.Jain Department of materials Science and Engineering Indian Institute of Technology DelhiNew Delhi 110016India School of metallurgy and materials University of BirminghamEdgbastonBirmingham B152TTUK Department of materials Science and Engineering Indian Institute of Technology KanpurUttar Pradesh 208016India

This review paper provides an overview of the micropillar compression technique as applied to magnesium(mg) and its alloys. It explores the influence of various factors, such as pillar size, shape, temperature, and strain rate on the mechanical properties of ***, the impact of alloying elements, aging, and precipitates in mg alloys has been extensively examined, revealing their significant influence on mechanical performance. The study highlights the strength and strain hardening improvements in mg with decreasing pillar size in micropillar compression. Furthermore, the role of precipitates as strengthening agents, affecting deformation mechanisms and overall mechanical response, is explored. These valuable insights are crucial for designing mg-based materials with enhanced mechanical properties for advanced engineering applications.

关键词： A review of challenges and opportunities in micropillar compression studies in mg alloys

Urban heat mitigation by green and blue infrastructure:Drivers,effectiveness,and future needs

在线全文

学校读者我要写书评

暂无评论

The Innovation 2024年第2期5卷 145-166页

作者： Prashant Kumar Sisay E.Debele Soheila Khalili Christos H.Halios Jeetendra Sahani Nasrin Aghamohammadi maria de Fatima Andrade maria Athanassiadou Kamaldeep Bhui Nerea Calvillo Shi-Jie Cao Frederic Coulon Jill L.Edmondson David Fletcher Edmilson Dias de Freitas Hai Guo matthew C.Hort madhusudan Katti Thomas Rodding Kjeldsen Steffen Lehmann Giuliano maselli Locosselli Shelagh K.malham Lidia morawska Rajan Parajuli Christopher D.F.Rogers Runming Yao Fang Wang Jannis Wenk Laurence jones Global Centre for Clean Air Research(GCARE) School of SustainabilityCivil and Environmental EngineeringFaculty of Engineering and Physical SciencesUniversity of SurreyGuildford GU27XHUK Institute for Sustainability University of SurreyGuildford GU27XHSurreyUK School of Built Environment University of ReadingWhiteknightsReading RG66BUUK School Design and the Built Environment Curtin University Sustainability Policy InstituteKent StBentley 6102Western Australia Harry Butler Institute Murdoch UniversityMurdoch 6150Western Australia Atmospheric Sciences Department Institute of AstronomyGeophysics and Atmospheric SciencesUniversity of Sao PauloSao Paulo 05508-090Brazil met Office FitzRoy RoadExeter EX13PBUK Department of Psychiatry and Nuffield Department of Primary Care Health Sciences Wadham CollegeUniversity of OxfordOxfordUK Centre for Interdisciplinary methodologies University of WarwickWarwickUK School of Architecture Southeast University2 SipailouNanjing 210096China Cranfield University School of WaterEnvironment and EnergyCranfield MK430ALUK Plants PhotosynthesisSoil ClusterSchool of BiosciencesUniversity of SheffieldSheffield S102TNUK UK Centre for Ecology&Hydrology Environment Centre WalesDeiniol RoadBangor LL572UWUK Air Quality Studies Department of Civil and Environmental EngineeringThe Hong Kong Polytechnic UniversityHong KongChina Department of Forestry and Environmental Resources Faculty Excellence Program for Leadership in Public ScienceNorth Carolina State UniversityChancellorRaleighNC 27695USA Departments of Architecture&Civil Engineering and Chemical EngineeringUniversity of BathBath BA27AYUK School of Architecture University of NevadaLas VegasNV 89154USA Department of Tropical Ecosystems Functioning Center of Nuclear Energy in AgricultureUniversity of São PauloPiracicaba 13416-000Sao PauloBrazil School of Ocean Sciences Bangor UniversityMenai BridgeAnglesey LL595 ABUK International Laboratory for Air Quality and Health Science and Engine

The combination of urbanization and global warming leads to urban overheating and compounds the frequency and intensity of extreme heat events due to climate ***,the risk of urban overheating can be mitigated by urban green-blue-grey infrastructure(GBGI),such as parks,wetlands,and engineered greening,which have the potential to effectively reduce summer air *** many reviews,the evidence bases on quantified GBGI cooling benefits remains partial and the practical recommendations for implementation are *** systematic literature review synthesizes the evidence base for heat mitigation and related co-benefits,identifies knowledge gaps,and proposes recommendations for their implementation to maximize their *** screening 27,486 papers,202 were reviewed,based on 51 GBGI types categorized under 10 main *** GBGI(green walls,parks,street trees)have been well researched for their urban cooling ***,several other GBGI have received negligible(zoological garden,golf course,estuary)or minimal(private garden,allotment)*** most efficient air cooling was observed in botanical gardens(5.0±3.5℃),wetlands(4.9±3.2℃),green walls(4.1±4.2℃),street trees(3.8±3.1℃),and vegetated balconies(3.8±2.7℃).Under changing climate conditions(2070–2100)with consideration of RCP8.5,there is a shift in climate subtypes,either within the same climate zone(e.g.,Dfa to Dfb and Cfb to Cfa)or across other climate zones(e.g.,Dfb[continental warm-summer humid]to BSk[dry,cold semi-arid]and Cwa[temperate]to Am[tropical]).These shifts may result in lower efficiency for the current GBGI in the *** the importance of multiple services,it is crucial to balance their functionality,cooling performance,and other related co-benefits when planning for the future *** global GBGI heat mitigation inventory can assist policymakers and urban planners in prioritizing effective interventions to reduce the risk of urban overheating,fi

关键词： estuary walls extreme

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

用补偿膜改善液晶显示器的视角特性

现代显示 1998年第3期 4-12页

作者：宫绍琴 J.Kanicki 徐刚 A.Abileah m.jones R.Brinkley S.Thomsen 美国密执安大学电子工程和计算机科学系显示技术与制造中心美国光学成像系统公司

评述用补偿膜改善ＬＣＤ，特别是ＴＮＡＭＬＣＤ视角特性的方法，介绍不同种类的补偿膜及其特性的表征。对各种ＬＣＤ的膜补偿设计的原理和设计上的折衷方案进行了讨论。

关键词： LCD 补偿膜视角液晶显示器