检索结果-南通市图书馆

Comparison of Perovskite Systems Based on AFeO_(3)(A=Ce,La,Y)in CO_(2) Hydrogenation to CO

在线全文

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2024年第4期30卷 337-358页

作者： Anna n.Matveyeva Shamil O.Omarov Laboratory of Materials and Processes for Hydrogen Energy Ioff e Institute194021 St.PetersburgRussia

CO_(2) is the most cost-eff ective and abundant carbon resource,while the reverse water-gas reaction(rWGS)is one of the most eff ective methods of CO_(2) *** work presents a comparative study of rWGS activity for perovskite systems based on AFeO_(3)(where A=Ce,La,Y).These systems were synthesized by solution combustion synthesis(SCS)with diff erent ratios of fuel(glycine)and oxidizer(φ),diff erent amounts of nH 4 nO_(3),and the addition of alumina or silica as *** techniques,including X-ray diff raction analysis,thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,energy-dispersive X-ray spectroscopy,n 2-physisorption,H_(2) temper-ature-programmed reduction,temperature-programmed desorption of H_(2) and CO_(2),Raman spectroscopy,and in situ FTIR,were used to relate the physicochemical properties with the catalytic performance of the obtained *** specifi c perovskite-containing system(either bulk or supported)has its own optimalφand nH_(4) nO_(3) amount to achieve the highest yield and dispersion of the perovskite *** all synthesized systems,bulk SCS-derived La-Fe-O systems showed the highest resistance to reducing environments and the easiest hydrogen desorption,outperforming La-Fe-O produced by solgel combustion(SGC).CO_(2) conversion into CO at 600°C for bulk ferrite systems,depending on the A-cation type and preparation method,follows the order La(SGC)nces in properties between La-Fe-O obtained by the SCS and SGC methods can be attributed to diff erent ratios of oxygen and lanthanum vacancy contributions,hydroxyl coverage,morphology,and free iron oxide *** situ FTIR data revealed that CO_(2) hydrogenation occurs through formates generated under reaction conditions on the bulk system based on La-Fe-O,obtained by the SCS method.γ-Al_(2)O_(3) improves the dispersion of CeFeO_(3) and LaFeO_(3) phases,the specifi c surface area,and the quant

关键词： Perovskites LaFeO_(3) CeFeO_(3) YFeO_(3) Solution combustion synthesis CO_(2) hydrogenation Reverse water–gas reaction(rWGS)

Developing knn forest data imputation for Catalonia

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2024年第4期35卷 142-155页

作者： Timo Pukkala núria Aquilué Ariadna Just Jordi Corbera Antoni Trasobares Forest Science and Technology Centre of Catalonia(CTFC) Crta.de St.Llorençde MorunysKm 225280 SolsonaSpain Cartographic and Geological Institute of Catalonia(ICGC) 08038 BarcelonaSpain

The combined use of LiDAR(Light Detection And Ranging)scanning and field inventories can provide spatially continuous wall-to-wall information on forest *** information can be used in many ways in forest mapping,scenario analyses,and forest manage-ment *** study aimed to find the optimal way to obtain continuous forest data for Catalonia when using knn imputation(knn stands for“k nearest neighbors”).In this method,data are imputed to a certain location from k field-measured sample plots,which are the most similar to the location in terms of LiDAR metrics and topographic *** multidimensional Euclidean distance was used as the similarity *** study tested two different methods to optimize the distance *** first method optimized,in the first step,the set of LiDAR and topographic variables used in the measure,as well as the transformations of these *** weights of the selected variables were optimized in the second *** other method optimized the variable set as well as their transformations and weights in one single *** two-step method that first finds the variables and their transfor-mations and subsequently optimizes their weights resulted in the best imputation *** the study area,the use of three to five nearest neighbors was *** and latitude turned out to be the most important variables when assessing the similarity of two locations of Catalan forests in the context of knn data *** optimal distance measure always included both LiDAR metrics and topographic *** study showed that the optimal similarity measure may be different for different ***,it was suggested that knn data imputation should always be started with the optimization of the measure that is used to select the k nearest neighbors.

关键词： Forest inventory Differential evolution Simulated annealing LiDAR

Analysis of natural vibration of truncated conical shells partially filled with fluid

在线全文

学校读者我要写书评

暂无评论

International Journal of Mechanical System Dynamics 2024年第2期4卷 142-152页

作者： Sergey A.Bochkarev Sergey v.Lekomtsev Laboratory of Functional Materials Institute of Continuous Media MechanicsUral Branch of Russian Academy of SciencesPermRussian Federation

In this paper,we study the vibrational behavior of shells in the form of truncated cones containing an ideal compressible *** sloshing effect on the free surface of the fluid is *** dynamic behavior of the elastic structure is investigated based on the classical shell theory,the constitutive relations of which represent a system of ordinary differential equations written for new *** fluid vibrations are described in terms of acoustic approximation using the wave equation for hydrodynamic pressure written in spherical *** transformation into the system of ordinary differential equations is carried out by applying the generalized differential quadrature *** formulated boundary value problem is solved by Godunov's orthogonal sweep *** frequencies of shell vibrations are calculated using the stepwise procedure and the Muller *** accuracy and reliability of the obtained results are estimated by making a comparison with the known numerical and analytical *** dependencies of the lowest frequency on the fluid level and cone angle of shells under different combinations of boundary conditions(simply supported,rigidly clamped,and cantilevered shells)have been studied *** conical straight and inverted shells,a numerical analysis has been performed to estimate the possibility of finding configurations at which the lowest natural frequencies exceed the corresponding values of the equivalent cylindrical shell.

关键词： classical shell theory conical shell Godunov's orthogonal sweep method ideal compressible fluid generalized differential quadrature method natural vibrations

Late neoproterozoic to early Cambrian high-grade metamorphism from Mikir Hills(Assam-Meghalaya gneissic Complex,northeast India):Implications for eastern Gondwana assembly

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2024年第5期15卷 256-282页

作者： Rahul nag H.Hrushikesh nathan Cogné n.Prabhakar Department of Earth Sciences Indian Institute of Technology BombayPowaiMumbaiMaharastra 400076India Geological Survey of India Northeastern RegionGuwahatiAssam 781005India Géosciences Rennes UMR6118CNRS Universitéde RennesFrance

Mikir Hills region,which represents the eastern segment of the Assam-Meghalaya Gneissic Complex(AMGC)in northeast India,constitutes part of the Eastern *** Mikir Hills preserves multiple metamorphic and magmatic events ranging from Early Mesoproterozoic to Early *** of these events,documenting the late neoproterozoic to early Cambrian tectonothermal events is helpful in correlating the continental blocks of Eastern *** present an integrated study involving field relations,petrology,P-T history and zircon-monazite geochronology of hitherto poorly studied pelitic and quartzo-feldspathic gneisses from the Mikir Hills *** gneisses have experienced at least three deformation events(D_(1),D_(2) and D_(3))with dominant foliation indicated by EnE-WSW striking and shallow-moderately dipping(neissic *** peak metamorphism in pelitic and quartzo-feldspathic gneisses is characterized by garnet(core)-K-feldspar-sillimanite-plagioclase-bio tite-rutile-quartz-ilmenite-melt and garnet-plagioclase-K-feldspar-biotite-quartz-ilmenite-melt assemblages,*** application of thermobarometric methods constrains the peak P-T conditions of 7.5-8.4 kbar at 674-778℃and 6.7-7.4 kbar at 601-618℃for pelitic and quartzofeldspathic gneisses,*** results are consistent with the values estimated using phase equilibria modelling and melt reintegration *** results of pseudosection modelling suggests a clockwise P-T path for pelitic gneisses involving migmatisation during peak metamorphism followed by near isothermal decompression from 8.0 to 8.6 kbar at 768-780℃to 4.0-5.0 kbar at 720-765℃.In contrast,quartzo-feldspathic gneisses preserved slightly lower peak P-T conditions at 3.8-4.6 kbar and 590-650℃.The U-Pb zircon dating of migmatised pelitic and quartzo-feldspathic gneisses yielded concordant ages of 1647±11 Ma and 1590±7 Ma,*** dates represent the inherited igneous protolith components,possibly

关键词： Gondwana Assam-Meghalaya Gneissic Complex Migmatisation neoproterozoic Geochronology P-T-t history

Hepatolithiasis:Epidemiology,presentation,classification and management of a complex disease

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 2024年第13期30卷 1836-1850页

作者： Rodrigo v.Motta Francesca Saffioti vasileios K Mavroeidis Translational Gastroenterology and Liver Unit Nuffield Department of MedicineUniversity of OxfordOxford OX39DUUnited Kingdom Department of Gastroenterology and Hepatology Oxford University Hospitals NHS Foundation TrustJohn Radcliffe HospitalOxford OX39DUUnited Kingdom UCL Institute for Liver and Digestive Health and Sheila Sherlock Liver Unit Royal Free Hospital and University College LondonLondon NW32QGUnited Kingdom Department of HPB Surgery Bristol Royal InfirmaryUniversity Hospitals Bristol and Weston NHS Foundation TrustBristol BS28HWUnited Kingdom Department of Transplant Surgery North Bristol NHS TrustSouthmead HospitalBristol BS105NBUnited Kingdom Department of Gastrointestinal Surgery North Bristol NHS TrustSouthmead HospitalBristol BS105NBUnited Kingdom

The term hepatolithiasis describes the presence of biliary stones within the intrahepatic bile ducts,above the hilar confluence of the hepatic *** disease is more prevalent in Asia,mainly owing to socioeconomic and dietary factors,as well as the prevalence of biliary *** the last century,owing to migration,its global incidence has *** main pathophysiological mechanisms involve cholangitis,bile infection and biliary strictures,creating a self-sustaining cycle that perpetuates the disease,frequently characterised by recurrent episodes of bacterial infection referred to as syndrome of“recurrent pyogenic cholangitis”.Furthermore,long-standing hepatolithiasis is a known risk factor for development of intrahepatic *** classifications have aimed at providing useful insight of clinically relevant aspects and guidance for *** management of symptomatic patients and those with complications can be complex,and relies upon a multidisciplinary team of hepatologists,endoscopists,interventional radiologists and hepatobiliary surgeons,with the main goal being to offer relief from the clinical presentations and prevent the development of more serious *** comprehensive review provides insight on various aspects of hepatolithiasis,with a focus on epidemiology,new evidence on pathophysiology,most important clinical aspects,different classification systems and contemporary management.

关键词： Cholelithiasis Intrahepatic stones Cholangiocarcinoma Biliary parasites Recurrent pyogenic cholangitis Oriental cholangiohepatitis Hepatectomy Cholangioscopy Liver transplant Paediatric

Classification of Rings Associated with the Genus of Clean Graphs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Algebra Colloquium 2024年第3期31卷 451-466页

作者： v.Ramanathan C.Selvaraj Aaqib Altaf S.Pirzada Department of Mathematics Periyar UniversitySalem 636011Tamil NaduIndi Department of Mathematics University of KashmirHazratbalSrinagarKashmirIndia

Let R be a ring(not necessarily commutative)with identity 1 and let CL(R)be its clean *** this paper,we investigate the genus number of the compact Riemann surface in which CL(R)can be embedded and explicitly determine all commutative rings R(up to isomorphism)such that CL(R)has genus at most *** is shown that for any Artinian ring R,CL(R)is a projective graph if and only if R is isomorphic to ***,we determine all isomorphism classes of commutative rings whose clean graphs have crosscap two.

关键词： clean graph commutative ring planar graph genus crosscap

Hard life for sons in the nest?Sex-dependent offspring mortality in Great Tits in urban and forest areas

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Avian Research 2024年第1期15卷 91-97页

作者： nora Agh Henriett Anna Dalvári Krisztián Szabó Ivett Pipoly András Liker HUn-REn-PE Evolutionary Ecology Research Group University of PannoniaH-8200VeszpremPf.1158.Hungary Behavioral Ecology Research Group Center for Natural SciencesUniversity of PannoniaH-8200Pf.1158.VeszpremHungary Molecular Ecology Research Group Department of EcologyUniversity of Veterinary Medicine BudapestH-1400Pf.2.BudapestHungary Synlab Hungary Ltd. H-1211Weiss Manfr´ed Str.5-7BudapestHungary

Sex-biased mortality can occur in birds during development,for example due to sexual differences in energy requirement and/or environmental sensitivity,or the effects of sex hormones or sex differences in the expression of mutations linked to sex *** extent of sex-bias in mortality may also be related to environmental conditions that influence offspring development and *** areas often provide poorer conditions for nestling development resulting in higher offspring mortality compared to natural areas,which may accelerate sex differences in offspring mortality in *** test this hypothesis,we examined the sex ratio of dead offspring in Great Tits(Parus major),using 427 samples of unhatched eggs and dead nestlings collected in two urban and two forest sites between 2013 and *** ratio of males in the whole sample of dead offspring(56.9%)was significantly higher than expected by an 1:1 ratio,and the strongest sex biases were detected in urban areas(57.6%males)and in young nestlings(ver,the sex ratios of dead offspring did not differ significantly among study sites and between offspring developmental stages.29.3%of unhatched eggs contained a visible embryo,and the proportion of embryo-containing unhatched eggs did not differ significantly between urban and forest study *** results suggest male-biased offspring mortality in Great Tits,and highlight the need of large datasets to detect subtle differences between habitats and developmental stages.

关键词： Great Tit Urbanization nestling mortality Sex related differences

Application of thermally stimulated acoustic emission method to assess the thermal resistance and related properties of coals

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2018年第2期28卷 243-249页

作者： E.A.novikov R.O.Oshkin v.L.Shkuratnik S.A.Epshtein n.n.Dobryakova national University of Science and Technology(MISiS) Moscow 119049Russia

Traditional methods of coal thermal resistance characterization are informative but considerably timeconsuming and require utilization of a complex and expensive equipment. This limits the effectiveness of their application. In this paper, authors experimentally investigated potential application of thermally stimulated acoustic emission method for developing of relatively simple and rapid coals thermal resistance assessment method. Features of thermally stimulated acoustic emission of anthracite, lignites and bituminous coal samples subject to cyclic thermal loading have been experimentally *** the first time, it has been shown that there exists a relationship of such patterns with structural parameters and properties of the coal samples, as well as their thermal resistance. The results indicate the possibility of applying the method of thermally stimulated acoustic emission to control processes of cryogenic disintegration and thermal resistance of fossil coals. The description of the equipment and methodological support needed for the implementation of this method have been provided.

关键词： Acoustic emission Fossil coal Thermal resistance Cryogenic disintegration Structure Properties

Effectiveness of external prestressing in enhancing the non-ductile hanger failure mechanism in reinforced concrete inverted T-beams

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第7期18卷 1050-1065页

作者： Ahmed M.ATTA Reda n.BEHIRY Mohammed I.HARAZ Structural Engineering Department Faculty of EngineeringTanta UniversityTanta 33511Egypt nile Higher Institute for Engineering and Technology Mansoura 11001Egypt

Recently,inverted T-beams have been used in reinforced concrete(RC)bridges to support transverse precast *** T-beams,contrary to practice with conventional beams,are loaded on the flanges upper *** loading configuration causes hanger failure due to the generation of vertical tensile stresses near the bottom of the *** key purpose of this study is to investigate the efficiency of vertical external prestressing stainless-steel bars in mitigating non-ductile hanger failure in reinforced concrete inverted *** experimental study on six inverted-T beams,including two un-strengthened specimens,was carried *** study showed that the value of the prestressing level had a considerable impact on the performance of hanger mechanism in relation to crack pattern,ultimate loads,cracking behavior,load-deflection,strains,and *** experimental results indicated that the suggested method for strengthening inverted T-beams had efficacy in reducing the seriousness of the non-ductile hanger failure and resulted in a strength increase of up to 53% when compared to that of the un-strengthened ***,two analytical models for estimating the hanger capacity and the average crack width of the strengthened RC inverted T-beams were *** models that were proposed exhibited a high degree of agreement with the experimental results.

关键词： RC bridges inverted T-beams strengthening hanger failure external prestressing