检索结果-南通市图书馆

EXTRAPOLATION AND A-POSTERIORI ERROR ESTIMATORS OF PETROV-gALERKIN METHODS FOR NON-LINEAR VOLTERRA INTEgRO-DIFFERENTIAL EQUATIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2001年第4期19卷 407-422页

作者： Shu-hua Zhang (Department of Mathematical Sciences, University of Alberta, Edrmonton, Alberta, Canada T6g 2g1) Tao Lin (Department of Mathematics, Virginia Tech, Blacksburg VA 24061) Yan-ping Lin (Department of Mathematical Sciences, University of Alberta University of Alberta 加拿大 T6G 2G1 Virginia Tech 美国 VA 24061 University of Alberta 加拿大 T6G 2G6

In this paper we will show that the Richardson extrapolation can be used to enhance the numerical solution generated by a Petrov-galerkin finite element method for the initial value problem for a nonlinear Volterra integro-differential equation. As by-products, we will also show that these enhanced approximations can be used to form a class of posteriori estimators for this Petrov-galerkin finite element method. Numerical examples are supplied to illustrate the theoretical results.

关键词： Volterra integro-differential equations Petrov-galerkin finite element methods Asymptotic expansions Interpolation post-processing A-posteriori error estimators.

Effect of high anodic polarization on the passive layer properties of superduplex stainless steel friction stir welds at different chloride electrolyte pH values and temperatures

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2019年第6期26卷 710-721页

作者： L.A.Santa-Cruz g.Machado A.A.Vicente T.F.C.Hermenegildo T.F.A.Santos Department of Mechanical Engineering Universidade Federal de PernambucoAv.da Arquiteturas/n50740-550RecifePEBrazil Center of Nanotechnology Centro de Tecnologias Estratégicas do NordesteCETENERecifePEBrazil Department of Chemical Engineering Universidade de Sao PauloSao PauloSPBrazil

The conditions used for friction stir welding of duplex stainless steels determine the resulting mechanical and corrosion performance of the *** study investigates the corrosion resistance of UNS S32750 and S32760 superduplex stainless steels(SDSSs)joined by friction stir welding,employing cyclic polarization,Mott–Schottky,and microscopy techniques for *** microscopy images indicated the presence of a deleterious intermetallic phase after electrolytic etching of S32760,as well as decreased corrosion *** presence of molybdenum in the steels promoted better passive behavior at low *** Mott–Schottky curves revealed p-n heterojunction behavior of the passive *** acquired after the polarization test by scanning electron microscopy showed higher passivation propensity with increases of temperature and pH.

关键词： superduplex stainless steel friction stir welding corrosion resistance cyclic polarization Mott–Schottky

STUDY ON CHEMICAL COMPOSITIONS OF 19 L AND LL CHONDRITES AND ITS APPLICATION IN TAXONOMY

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 1986年第2期29卷 214-224页

作者：王道德,g.W.KALLEMEYN,J.T.WASSON guiyang Institute of geochemistry Academia Sinica Institute of geophysics and Planetary Physics University of California Los Angeles CA 90024 U. S. A. Institute of geophysics and Planetary Physics University of California Los Angeles CA 90024 U. S. A.

Reported in this paper are precise INAA data on 19 L and LL chondrites (7 Chinese chondrites and 12 from other countries). The L and LL chondrite data normalized to Mg and to CI chondrite indicate that for several lithophiles (V, Al, Cr and Mn), the extent of scatter is low, similar to that observed in carbonaceous chondrites. The average concentration of siderophiles in the LL group is lower than that in the L *** the basis of olivine composition and atomic ratio (Ir/Au), we reclassify the five previously labeled L ehondrites as LL members. The atomic ratios of Ir/Au in the LL chondrites are lower than those in the L chondrites (the division is set at an Ir/Au ratio of 2.5). The atomic ratio of Ir/Au appears to be a useful classification parameter for ordinary chondrites. Therefore, it can be considered as a new taxonomic parameter. Of the elements studied, Br, a high volatile, seems most likely to show thermometamorphic effects, depending on petrologic types. The concentration of bromine and the

关键词： INAA STUDY ON CHEMICAL COMPOSITIONS OF 19 L AND LL CHONDRITES AND ITS APPLICATION IN TAXONOMY Ni FeO La than Co

Neutrosophicκ-Structures in Ordered Semigroups

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2022年第5期130卷 979-999页

作者： g.Muhiuddin K.Porselvi B.Elavarasan D.Al-Kadi Department of Mathematics Faculty of ScienceUniversity of TabukTabuk71491Saudi Arabia Department of Mathematics Karunya Institute of Technology and SciencesCoimbatore641114India Department of Mathematics and Statistic College of ScienceTaif UniversityTaif21944Saudi Arabia

In general,ordered algebraic structures,particularly ordered semigroups,play an important role in fuzzification in many applied areas,such as computer science,formal languages,coding theory,error correction,***,the concept of ambiguity is important in dealing with a variety of issues related to engineering modeling problems,network theory,decision-making problems in real-life situations,and so *** theories have been developed by various researchers to overcome the difficulties that arise from uncertainty,including fuzzy sets,intuitionistic fuzzy sets,probability,softsets,neutrosophic sets,***,we focus solelyonneutrosophic set *** ordered semigroups,we define and investigate the properties of neutrosophicκ-ideals and neutrosophicκ-interior *** also use neutrosophicκ-ideals and neutrosophicκ-interior ideals to characterize ordered semigroups.

关键词： Ordered semigroup ideals neutrosophicκ-structures neutrosophicκ-ideals neutrosophicκ-interior ideals

Presence of thyroid-associated ophthalmopathy in Hashimoto's thyroiditis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Ophthalmology(English edition) 2014年第4期7卷 644-647页

作者： Emrah Kan Elif Kilic Kan gülcin Ecemis Ramis Colak Department of Ophthalmology Samsun Training and Research Hospital Department of Endocrinology and Metabolism Ondokuz Mayis University Department of Endocrinology and Metabolism Sevgi Atasagun State Hospital

·AIM: To determine the prevalence of ophthalmopathy in Hashimoto’s patients and to make a comparison in subgroups of patients·METHODS: The study involved 110 Hashimoto’s thyroiditis patients and 50 control subjects attending to the endocrinology department of the hospital. Subgroup classification of patients was made as euthyroid,subclinic and clinic in Hashimato’s thyroiditis. All patients were evaluated by a single experienced ophthalmologist for the prevalence and characteristics of eye signs.·RESULTS:Theoverallprevalencesofeyechanges were22.7%(25 patients) in patients and 4%(2 persons) in control subjects respectively(P =0.002). In patients the most common symptom was retrobulbar eye pain with or without any eye movement. Thirteen patients had significant upper eyelid retraction(11.8%). Six patients had eye muscle dysfunction as reduced eye movements in up gaze. In control patients one person had proptosis and another had lid retraction. The clinical activity score and classification of the ophthalmopathy did not show any significant differences among subgroups.·CONCLUSION:Theeyesignsweremostlymild(22.7%)and the most common eye sign was the presence of upper eyelid retraction(11.8%). Additionally six patients had eye muscle dysfunction as reduced eye movements in up gaze. Therefore we recommend to make a routine ophthalmic examination in Hashimoto’s thyroiditis patients in order not to omit the associated ophthalmopathy.

关键词： graves' ophthalmopathy Hashimoto's thyroiditis upper eyelid retraction thyroid-associated ophthalmopathy

Preparation and Microstructural Characterization of Activated Carbon-Metal Oxide Hybrid Catalysts:New Insights into Reaction Paths

维普期刊数据库评论

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 Materials Science & Technology 2015年第8期31卷 806-814页

作者： A.Barroso-Bogeat M.Alexandre-Franco C.Fernndez-gonzlez V.gómez-Serrano Department of Organic and Inorganic Chemistry Faculty of SciencesUniversity of Extremadura

In catalysis processes, activated carbon （AC） and metal oxides （MOs） are widely used either as catalysts or as catalyst supports because of their unique properties. A combination of AC and MO nanoparticles in a single hybrid material usually entails both chemical and microstructural changes, which may largely influence the potential catalytic suitability and performance of the resulting product. Here, the prepa- ration of a wide series of AC-MO hybrid catalysts is studied. Three series of such catalysts are prepared by support first of MO （Al2O3, Fe2O3, SnO2, TiO2, WO3, and ZnO） precursors on a granular AC by wet impregnation and oven-drying at 120 ℃, and by subsequent heat treatment at 200 or 850℃ in inert atmosphere. Both the chemical composition and microstructure are mainly investigated by powder X-ray diffraction. Yield and ash content are often strongly dependent on the MO precursor and heat treatment temperature, in particular for the Sn catalysts. With the temperature rise, trends are towards the transformation of metal hydroxides into metal oxides, crystallinity improvement, and occurrence of drastic composition changes, ultimately leading to the formation of metals in elemental state and even metal carbides. Reaction paths during the preparation are explored for various hybrid catalysts and new insights into them are provided.

关键词： Activated carbon Metal oxides Hybrid catalysts Preparation Microstructural characterization X-ray diffraction

The Introduction of Bedaquiline Regimen for Drug-Resistant Tuberculosis in the Philippines: An Operational Study

在线全文

学校读者我要写书评

暂无评论

Journal of Tuberculosis Research 2022年第4期10卷 205-219页

作者： Vincent M. Balanag Jr. Vivian S. Lofranco Mariquita J. Mantala Mary Rosary T. Santiago Patrice Jamie E. Cabasis Arnyl g. Araneta Anna Marie Celina g. garfin Lung Center of the Philippines National Center for Pulmonary Research Quezon Philippines Department of Health National Tuberculosis Control Program Management Office Manila Philippines Philippine Business for Social Progress The Global Fund Project Manila Philippines Department of Health Disease Prevention and Control Bureau Manila Philippines

Objectives: Bedaquiline (BDQ) is the first new anti-tuberculosis (TB) drug introduced to the market after 45 years. Recent studies have shown the potential benefits of adding bedaquiline to regimens for drug-resistant TB (DR-TB). In search of more effective regimens for DR-TB, bedaquiline was introduced in the TB program in the Philippines under operational research to assess its effectiveness, safety, and tolerability when given with background regimens among patients with multi-or extensively DR-TB (MDR/XDR-TB). Design: A prospective cohort study of patients with MDR/XDR-TB was given with a bedaquiline-containing regimen from June 2016 to May 2017. Demographic data, presence of comorbidities, and microbiologic profile on entry were recorded. Bedaquiline was administered at the recommended dose of 400 mg once daily for 14 days, then 200 mg three times a week for 22 weeks together with World Health Organization (WHO)-compliant background regimen. The time to culture conversion, interim outcomes at the 6th month of treatment, end-of-treatment outcomes, and post-treatment follow-up outcomes after one year was determined. The frequency and severity of adverse events (SAE) were recorded as part of pharmacovigilance. Results: Seventy-five patients were given with bedaquiline-containing regimen during the study period. Forty-two (56.0%) had second-line injectable resistance, 23 (30.7%) had fluoroquinolone-resistance, 6 (8.0%) had MDR-TB, and 4 (5.3%) had XDR-TB. In the 6th month of post-enrolment, 79% were culture-negative. The treatment success rate was 65.3% (37 were cured and 12 completed treatment), 7 (9.3%) died, 17 (22.7%) lost to follow-up, and 2 (2.7%) were withdrawn from treatment. Adverse events included vomiting (80%), dizziness (69%), nausea (52%), cough (44%), and headache (36%). The post-treatment follow-up of 49 patients in the 12th month showed 92% were culture-negative while 8% of TBC were not done. Conclusion: Bedaquiline-containing regimens for patients

关键词： Bedaquiline Drug-Resistant TB XDR-TB

Formability of friction stir processed low carbon steels used in shipbuilding

维普期刊数据库评论

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 Materials Science & Technology 2018年第1期34卷 237-244页

作者： D.M. Sekban S.M. Akterer O. Saray Z.Y. Ma g. Purcek Department of Naval Architecture and Marine Engineering Karadeniz Technical University Trahzon Turkey Department of Autumotive Technology RecepTayyip Erdogan University Rize Turkey Department of Mechanical Engineering Bursa Technical University. Bursa Turkey Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Mechanical Engineering. Karadeniz Technical University Trabzon Turkey Engineering Faculty Giresun University Giresun Turkey

The stretch formability of a low carbon steel processed by friction stir processing （FSP） was studied under biaxial loading condition applied by a miniaturized Erichsen test. One-pass FSP decreased the ferritic grain size in the processed zone from 25 μm to about 3 μm, which also caused a remarkable increase in strength values without considerable decrease in formability under uniaxial loading. A coarse-grained （Cg） sample before FSP reflected a moderate formability with an Erichsen index （EI） of 2.73 mm. FSP slightly decreased the stretch formability of the sample to 2.66 ram. However, FSP increased the required punch load （FEI） due to the increased strength by grain refinement. FSP reduced considerably the roughness of the free surface of the biaxial stretched samples with reduced orange peel effect. The average roughness value （Ra） decreased from 2.90 in the Cg sample down to about 0.65 μm in fine-grained （Fg） sample after FSP. It can be concluded that the Fg microstructure in low carbon steels sheets or plates used generally in shipbuilding provides a good balance between strength and formability.

关键词： Friction stir processing Low carbon shipbuilding steel Formability Microstructure Mechanical properties

CompactPCI/Linux Platform in FTU Slow Control System

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2004年第6期6卷 2535-2540页

作者： F.Iannone L.Wang C.Centioli M.Panella g.Mazza V.Vitale AssociazioneEuratom／ENEAsullaFusione CentroRicercheFrascati00044FrascatiItaly InstituteofPlasmaPhysics ChineseAcademyofSciencesHefei230031China

In large fusion experiments, such as tokamak devices, there is a common trendfor slow control systems. Because of complexity of the plants, the so-called 'Standard Model' (SM)in slow control has been adopted on several tokamak machines. This model is based on a three-levelhierarchical control: 1) High-Level Control (HLC) with a supervisory function; 2) Medium-LevelControl (MLC) to interface and concentrate I/O field equipments; 3) Low-Level Control (LLC) withhard real-time I/O function, often managed by PLCs. FTU control system designed with SM concepts hasunderwent several stages of developments in its fifteen years duration of runs. The latestevolution was inevitable, due to the obsolescence of the MLC CPUs, based on VME-MOTOROLA 68030 withOS9 operating system. A large amount of C code was developed for that platform to route the dataflow from LLC, which is constituted by 24 Westinghouse Numalogic PC-700 PLCs with about 8000field-points, to HLC, based on a commercial Object-Oriented Real-Time database on Alpha/CompaqTru64platform. Therefore, we have to look for cost-effective solutions and finally a CompactPCI—Intelx86 platform with Linux operating system was chosen. A software porting has been done, taking intoaccount the differences between OS9 and Linux operating system in terms of Inter/Network ProcessesCommunications and I/O multi-ports serial driver. This paper describes the hardware/softwarearchitecture of the new MLC system, emphasizing the reliability and the low costs of the open sourcesolutions. Moreover, a huge amount of software packages available in open source environment willassure a less painful maintenance, and will open the way to further improvements of the systemitself.

关键词： compact PCI/linux control system tokamak