检索结果-南通市图书馆

Hard rock tunnel boring m.c.ine penetration test as an indicator of chipping process efficiency

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 Rock m.c.anics and Geotechnical Engineering 2017年第4期9卷 611-622页

作者： m.c. Villeneuve Department of Geological Sciences University of Canterbury Christchurch 8140 New Zealand

The transition from grinding to chipping can be observed in tunnel boring m.c.ine(TBm) penetration test data by plotting the penetration rate(distance/revolution) against the net cutter thrust(force per cutter) over the full range of penetration rates in the *** penetration test data to the geological and geom.c.anical characteristics of rock masses through which a penetration test is conducted provides the ability to reveal the efficiency of the chipping process in response to changing geological *** test data can also be used to identify stress-induced tunnel face *** research shows that the strength of the rock is an important parameter for controlling how m.c. net cutter thrust is required to transition from grinding to *** also shows that the geological characteristics of a rock will determine how efficient chipping occurs once it has *** particular,geological characteristics that lead to efficient fracture propagation,such as fabric and m.c. contents,will lead to efficient *** findings will enable a better correlation between TBm performance and geological conditions for use in TBm design,as a basis for contractual payments where penetration rate dominates the excavation cycle and in further academ.c.investigations into the TBm excavation process.

关键词： Penetration rate Grinding chipping Geological characteristics Face stability

Spent coffee grounds as a renewable source of energy: An analysis of bulk powder flowability

在线全文

学校读者我要写书评

暂无评论

Particuology 2019年第2期17卷 92-100页

作者： L. massaro Sousa m.c. Ferreira Drying center for Pastes Suspensions and Seeds. Chemical Engineering Department Federal University of Sao Carlos. P.O. Box 676 13565-905 Sao Carlos Brazil

The main use for spent coffee grounds (ScG) produced in the soluble coffee industry is thermal energy generation in the industry itself. The ScG are processed using operations that are strongly dependent on powder flow behavior. In this study, we evaluated two classical flowability in dices of non-consolidated ScG powders: the angle of repose (AoR), and the Hausner ratio (HR). The influences of the mean particle diameter, particle size distribution (PSD), and water content on the AoR and HR values of ScG were analyzed for powders with a mean particle size range of 225-550 μm. For powders with a mean particle size close to 350 μm and for mixtures containing more than 40% fine particles, the HR (>1.35) and AoR (>45 °) values were characteristic of poor flowability. The AoR was sensitive to the powder PSD, and powders with similar mean particle sizes had higher AoR values when the PSD was larger. For powders w让h water contents up to 50%, the flowability indices were not greatly affected by the water content. A modified linear-mixture packing model was used to predict the packed bed void fractions for binary and ternary mixtures of the three base powders. The model was used to construct a ternary diagram to estimate the HR values of the mixtures. An equation was fitted to correlate HR and AoR. The proposed diagram and the equation provide insight into flow behavior and could be used for process design of industrial plants that handle ScG.

关键词： Spent coffee ground Biomass Flowability Hausner ratio Angle of repose

THE EFFEcT OF BORON AND cARBON ADDITION ON WELDABILITY OF DS TmS-75 SUPERALLOY

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 24-32页

作者： m.c. chaturvedi N.L. Richards Department of m.c.anical and Industrial Engineering University of manitoba Winnipeg Manitoba R3T 5V6 CanadaDepartment of Mechanical and Industrial Engineering University of Manitoba Winnipeg Manitoba R3T 5V6 Canada

Four alloys TmS-75 (Base), Base+B, Base+c and TmD-103 (Base+B+c) with varying levels of B, c were directionally solidified (DS), and their weldability was investigated by bead-on-plate electron beam welding. It was found that cracking occurred in the weld-metal, as well as in the heat affected zone (HAZ). Both γ/γ' and/or γ/carbide eutectic contributed to the weld-metal cracking, and the γ/γ' eutectic was found to be mainly responsible for cracking in HAZ. However, constitutional liquation of carbides seems to have made some contribution also. The B addition had a detrimental effect on HAZ cracking susceptibility, while c addition improved it appreciably even in the presence of B. In addition, no obvious differences were observed in cracking susceptibility of weld-metal in the four alloys. The cracking modes and m.c.anisms underlying the effect of B and c addition on weldability could be explained on the basis of m.c.ostructures of the four alloys.

关键词： Ni-based superalloy low melting point constituents liquation cracking

Thermal characteristics in the cutting of Inconel 718 Superalloy Using cW Nd:YAG Laser

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2010年第4期26卷 362-366页

作者： D.G. Ahn K.W. Byun m.c. Kang Department of m.c.anical Engineering Chosun University 375 Seosuk-dong Dong-gu Gwang-ju 501-759 Korea Hybrid materials Solution National core Research (NcRc) Pusan National University San 30 Changjeon-dong Keumjeong-gu Busan 609-735 Korea

The objective of the this study is to investigate the effects of cutting parameters on thermal characteristics, including practical cutting regions, the formation of the kerfwidth and the heat transfer phenomenon, in the cutting of Inconel 718 super-alloy sheets using a cW Nd：YAG laser. From the results of the experiments, the influence of process parameters on both the practical cutting region and the kerfwidth has been examined. In addition, it has been shown that the kerfwidth of the specimen lies in the range of 0.53-0.61 mm. In order to examine characteristics of the heat transfer during the laser cutting process, a three-dimensional quasi-steady heat transfer analysis has been performed using the commercial code SYSWELD V9.0. From the results of the analysis, the influence of cutting parameters on the temperature distribution in the vicinity of the cut section has been quantitatively evaluated. Based on these results, optimal cutting conditions have been estimated.

关键词： cW Nd:YAG laser Inconel 718 Kerfwidth Quasi-steady heat transfer analysis

Towards cr（VI）-free anodization of aluminum alloys for aerospace adhesive bonding applications： A review

在线全文

学校读者我要写书评

暂无评论

Frontiers of chem.c.l Science and Engineering 2017年第3期11卷 465-482页

作者： Shoshan T. Abrahami John m.m. de Kok Herman Terryn Johannes m.c. mol materials innovation institute (m2i) 2628 XG Delft The Netherlands Delft University of Technology Department of Materials Science and Engineering 2628 CD Delft The Netherlands Fokker Aerostructures BV 3351 LB Papendrecht The Netherlands Department of materials and chemistry Research Group Electrochemical and Surface Engineering (SURF) Vrije Universiteit Brussel 1050 Brussels Belgium

For more than six decades, chrom.c.acid anodizing （cAA） has been the central process in the surface pre-treatment of aluminum for adhesively bonded aircraft structures. Unfortunately, this electrolyte contains hexavalent chromium （cr（VI））, a compound known for its toxicity and carcinogenic properties. To comply with the new strict international regulations, the cr（VI）-era will soon have to come to an end. Anodizing aluminum in acid electrolytes produces a self-ordered porous oxide layer. Although different acids can be used to create this type of structure, the excellent adhesion and corrosion resistance that is currently achieved by the complete cr（VI）-based process is not easily matched. This paper provides a critical overview and appraisal of proposed alternatives to cAA, including combinations of multiple anodizing steps, pre- and post anodizing treatments. The work is presented in terms of the modifications to the oxide properties, such as morphological features （e.g., pore size, barrier layer thickness） and surface chemistry, in order to evaluate the link between fundamental principles of adhesion and bond performance.

关键词： aluminum cr(VI)-free surface pre-treat- merits anodizing adhesive bonding

metallographic Analyses of Laser Gladded Wc-Ni and Wc-co Hard-facing metals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

材料热处理学报 2004年第05B期25卷 996-999页

作者： HK chikwanda m.c.iremba c van Rooyen Department of chem.c.l &metallurgical Engineering Tshwane University of Technology Pretoria South Africa.Department of Chemical &Metallurgical Engineering Tshwane University of Technology Pretoria South Africa.National Laser Centre CSIR Pretoria South Africa

Laser cladding is performed to improve the surface properties of metallic m.c.ine components. Extensive work is being conducted to investigate the relationships among the cladding parameters, clad powder characteristics and the quality of the clad layer. This work presents some of the metallographic analyses results of Wc -Ni and Wc-co clad layers. The clad layers are characterised with non-uniform.c.rbide particles, mostly Wc imbedded in a more ductile matrix. The transition from the clad layer to the substrate metal had a distinct dilution zone. The ratio of this zone to the clad height was in the range of 10 -12% and this still needs to be refined.

关键词：激光包覆衬底合金包覆高度包覆深度 Wc-Ni Wc-co

Vascular plants distribution in relation to topography and environmental variables in alpine zone of Kedarnath Wild Life Sanctuary,West Himalaya

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 2018年第9期15卷 1936-1949页

作者： cHANDRA Sudeep SINGH Ankit SINGH c.P. NAUTIYAL m.c. RAWAT L.S. High Altitude Plant Physiology Research centre(HAPPRc)H.N.B.Garhwal University Srinagar Garhwal-246174UttarakhandIndia Space Applications centre (Indian Space Research Organization)Ahmedabad 380015India Govind Ballabh Pant National Institute of Himalayan Environment&Sustainable Development Garhwal Unit Srinagar Garhwal-246174UttarakhandIndia

The present study was carried out in Tungnath alpine meadows of Kedarnath Wild Life Sanctuary, Western Himalaya from subalpine to upper alpine zone. A total of four summits were selected along an altitudinal gradient and sampled for detailed vegetation analysis using multi summit approach as per Global observation research initiative in alpine environments(GLORIA). Species richness, diversity, and evenness among four summits as well as the interaction between environmental variables with plant communities were assessed. monthly mean soil temperature was calculated using data retrieved from geo-precision temperature logger in order to identify the trend of soil temperature among different season and altitudinal gradient and its implications to plant communities. Soil samples were analyzed fromeach summit by collecting randomized composite soil samples. The indirect non-metric multidimensional scaling(NmDS) and direct canonical correspondence analysis(ccA) tools of ordination techniques to determine the linkage between plant species from various sample summits and biotic/abiotic environmental gradients were used in the present study. The results of the study demonstrated increase in species richness as soil temperature increases, the ecotone representing summits were found most warm summits followed by highest species richness. Annual soil temperature increased by 1.43°c at timberline ecotone. Whereas, at upper alpine zone the soil temperature increased by 0.810 c from year 2015 to 2016. S?rensen's similarity index was found to be increased between subalpine and upper alpine zone with increase in the presence of subalpine plant species at upper alpine zone. Both the ordination tools separate the subalpine summit and their respective vegetation from summits representingtimberline ecotone and upper alpine zone. Soil p H, altitude, soil cation exchange capacity were found as the key abiotic drivers for distribution of plant species.

关键词： GLORIA Non-metric multidimensionalscaling (NmDS) canonical correspondence analysis(ccA) Ecotone West Himalaya

Surface charging activated m.c.anism.c.ange: A computational study of O, cO, and cO2 interactions on Ag electrodes

在线全文

学校读者我要写书评

暂无评论

Journal of Energy chemistry 2020年第11期29卷 307-313页

作者： Ilker Tezsevin mauritius c.m.van de Sanden Suleyman Er DIFFER-Dutch Institute for Fundamental Energy Research De Zaale 20Eindhoven 5612 AJThe Netherlands ccER-center for computational Energy Research DIFFER-Dutch Institute for Fundamental Energy ResearchDe Zaale 20Eindhoven 5612 AJThe Netherlands Department of Applied Physics Eindhoven University of TechnologyEindhoven 5600 MBThe Netherlands

Electrocatalytic and plasma-activated processes receive increasing attention in catalysis. Density functional theory(DFT) calculations are state-of-the-art tools for the fundamental study of reaction m.c.anisms and predicting the performance of catalytic materials. Proper application of DFT-based methods is crucial when investigating charge-doped electrode surfaces during electrocatalytic and plasma-activated reactions. Here, as a model electrode for plasma-activated cO2 splitting, we studied the interactions of O, cO, and cO2 with the neutral and progressively charged Ag(111) metal surfaces. We show that the application of correction procedures is necessary to obtain accurate adsorption energy profiles of O atoms,cO and cO2 molecules on Ag surfaces that are under the influence of additional electrons. Interestingly,the oxidation of cO is found to shift from a Langmuir–Hinshelwood m.c.anism on a neutral electrode to an Eley–Rideal m.c.anism on charged electrodes. Furthermore, we show that the surface charging of Ag(111) electrodes increase their cO2 reduction performance by enhancing the adsorption of O atoms and desorption of cO molecules. A further increase in the absolute charge-state of the electrode surface is expected to waive the thermodynam.c.barriers for the cO2 splitting reaction.

关键词： Density functional theory cO2 reduction Silver electrode Surface charge

Serological surveillance for SARS-coV-2 antibodies among students,faculty and staff within a large university system during the pandemic

在线全文

学校读者我要写书评

暂无评论

World Journal of Virology 2025年第1期14卷 99-107页

作者： marcos G Pinheiro Gabriela G O Alves maria Eduarda R conde Sofia L costa Regina c S Sant’Anna Isa m F Antunes mônica c carneiro Fabio S Ronzei Julia c Scaffo Felipe R Pinheiro Lialyz S Andre Helvecio c Povoa Valéria T Baltar Fabíola Giordani Eduarda S Hemerly Gisele c Alexandre Karla c de Paula márcio Watanabe Antonio claudio L da Nóbrega Jackeline christiane P Lobato Fabio Aguiar-Alves Laboratory of molecular Epidemiology and Biotechnology Rodolpho Albino University LaboratoryFluminense Federal UniversityNiterói 24241000Rio de JaneiroBrazil Estácio de SáUniversity Nova Friburgo 28611135Rio de JaneiroBrazil Pathology Program Medicine schoolFluminense Federal UniversityNiterói 24070090Rio de JaneiroBrazil Department of Pharm.c.utical Sciences Lloyd L.Gregory School of PharmacyPalm Beach Atlantic UniversityWest Palm BeachFL 33401United States Health Institute of Nova Friburgo Fluminense Federal UniversityNova Friburgo 28613001Rio de JaneiroBrazil Department of Epidemiology and Biostatistics Institute of Collective Health(ISC)Fluminense Federal UniversityNiterói 24033900Rio de JaneiroBrazil Institute of Physical Education Fluminense Federal UniversityNiterói 24020005Rio de JaneiroBrazil Department of Statistics Fluminense Federal UniversityNiterói 24210200Rio de JaneiroBrazil Department of Physiology and Pharm.c.logy Fluminense Federal UniversityNiterói 24210130Rio de JaneiroBrazil

BAcKGROUND At the end of December 2019,the world faced severe acute respiratory syndrome-coronavirus 2(SARS-coV-2),which led to the outbreak of coronavirus disease 2019(cOVID-19),associated with respiratory *** virus has shown significant challenges,especially for senior citizens,patients with other underlying illnesses,or those with a sedentary *** tests conducted early on have helped identify how the virus is transmitted and how to curb its *** study hypothesis was that the rapid serological test for SARS-coV-2 antibodies could indicate the immunoreactive profile during the cOVID-19 pandem.c.in a university *** To conduct active surveillance for serological expression of anti-SARS-coV-2 antibodies in individuals within a university setting during the cOVID-19 *** This sectional study by convenience sampling was conducted in a large university in Niteroi-RJ,Brazil,from march 2021 to July *** study population consisted of students,faculty,and administrative staff employed by the university.A total of 3433 faculty members,60703 students,and 3812 administrative staff were invited to *** were gathered through rapid serological tests to detect immunoglobulin(Ig)m and IgG against ***χ²or Fisher's exact test was used to conduct statistical analysis.A 0.20 significance level was adopted for variable selection in a multiple logistic regression model to evaluate *** A total of 1648 individuals were enrolled in the *** proportion of cOVID-19 positivity was 164/1648(9.8%).The adjusted logistic model indicate a positive association between the expression of Igm or IgG and age[odds ratio(OR)=1.16,95%cI:1.02-1.31](Pcontact with a cOVID-19-positive case(OR=3.49,95%cI:2.34-5.37)(Pceived the cOVID-19 vaccine(OR=2.33,95%cI:1.61-3.35)(Pcial isolation(OR=0.59,95%cI:0.41-0.84)(P<0.004).The likelihood of sho

关键词： Serological surveillance SARS-coV-2 antibodies cOVID-19 Serological rapid test Risk factors for cOVID-19