检索结果-南通市图书馆

Chinese Annals of Mathematics,Series B 2017年第2期38卷 601-628页

作者： Hoai-Minh NGUYEN epfl sb MATHAA CAMA Station 8CH-1015 LausanneSwitzerland

Negative index materials are artificial structures whose refractive index has negative value over some frequency range. These materials were first investigated theoretically by Veselago in 1946 and were confirmed experimentally by Shelby, Smith, and Schultz in2001. Mathematically, the study of negative index materials faces two difficulties. Firstly,the equations describing the phenomenon have sign changing coefficients, hence the ellipticity and the compactness are lost in general. Secondly, the localized resonance, i.e.,the field explodes in some regions and remains bounded in some others as the loss goes to 0, might appear. In this survey, the author discusses recent mathematics progress in understanding properties of negative index materials and their applications. The topics are reflecting complementary media, superlensing and cloaking by using complementary media, cloaking a source via anomalous localized resonance, the limiting absorption principle and the well-posedness of the Helmholtz equation with sign changing coefficients.

关键词： Negative index materials, Localized resonance, Cloaking, Superlensing

Finding Symmetry Groups of Some Quadratic Programming Problems

在线全文

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2023年第2期16卷 370-392页

作者： Anton V.Eremeev Alexander S.Yurkov Sobolev Institute of Mathematics sb RAS Omsk DepartmentOmskRussia Omsk Scientific Center sb RAS(Institute of Radiophysics and Physical Electronics) OmskRussia

Solution and analysis of mathematical programming problems may be simplified when these problems are symmetric under appropriate linear *** particular,a knowledge of the symmetries may help decrease the problem dimension,reduce the size of the search space by means of linear *** the previous studies of symmetries in the mathematical programming usually dealt with permutations of coordinates of the solutions space,the present paper considers a larger group of invertible linear *** study a special case of the quadratic programming problem,where the objective function and constraints are given by quadratic *** formulate conditions,which allow us to transform the original problem to a new system of coordinates,such that the symmetries may be sought only among orthogonal *** particular,these conditions are satisfied if the sum of all matrices of quadratic forms,involved in the constraints,is a positive definite *** describe the structure and some useful properties of the group of symmetries of the *** that,the methods of detection of such symmetries are outlined for different special cases as well as for the general case.

关键词： Non-convex programming orthogonal transformation symmetry group Lie group

Unveiling the Threat: Case Reports of Extra-Pulmonary Tuberculosis among Sanctuary Chimpanzees

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Infectious Diseases 2024年第1期14卷 105-132页

作者： Emeline Chanove Yedra Feltrer Antoine Collomb-Clerc Angela Ceballos-Caro Marina Spinu Department of Infectious Diseases University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Romania International Primate Health and Welfare Group (IPHWG) Madrid Spain NeuroX Institute and Brain Mind Institute School of Life Sciences Swiss Federal Institute of Technology (EPFL) Lausanne Switzerland Malaria and Emerging Parasitic Diseases Laboratory National Centre for Microbiology Instituto de Salud Carlos III Madrid Spain

Primate sanctuaries across Africa play a pivotal role in the rescue and rehabilitation of confiscated and rescued wild primates, many of whom have had extensive contact with humans prior to their arrival and throughout the rehabilitation process, heightening the risk of disease transmission. While tuberculosis is not naturally occurring in free-living chimpanzees, it has been extensively observed in captive primates that have been in close proximity to humans or other captive primates infected with Mycobacterium tuberculosis. This case report delves into an outbreak of extra-pulmonary tuberculosis among juvenile chimpanzees within a sanctuary, detailing the associated diagnostic challenges and treatment approaches. The five cases had close contact with a caregiver infected with tuberculosis, subsequently transmitting the infection to other in-contact chimpanzees. Prolonged treatment, employing the human protocol of quadri-therapy (rifampicin, isoniazid, pyrazinamide, and ethambutol), followed by bi-therapy (rifampicin and isoniazid), resulted in complete resolution for all five cases. These cases underscore the critical importance of maintaining high levels of biosecurity, implementing effective quarantine measures, and adhering to strict hygiene practices when working with non-human primates.

关键词： Extrapulmonary Tuberculosis Tuberculosis Chimpanzees Zoonotic Risk Biosecurity Diagnosis Challenges

Growth rate of CO_(2) hydrate film on water-oil and water-gaseous CO_(2) interface

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2023年第4期56卷 266-272页

作者： Tatyana P.Adamova Sergey S.Skiba Andrey Yu.Manakov Sergey Y.Misyura Kutateladze Institute of Thermophysics sb RAS Lavrentiev Ave.1Novosibirsk 630090Russian Federation

It is known that injection of carbon dioxide into the petroleum reservoir(CO_(2) flooding) is one of the effective methods for enhanced oil recovery. CO_(2) flooding may be complicated by formation of CO_(2) hydrate plugs. It makes topical investigation of CO_(2) hydrate formation in the system gaseous CO_(2)-oil-water. In this work, the growth rates of carbon dioxide hydrate films at the water-oil as well as the water-gas interface are studied in the pressure range of 2.30-3.04 MPa and at temperatures between -5.4 and 5.0℃. It is found that the growth rate for the water-oil interface is 3.5 times lower than that for the water-gas interface with carbon dioxide. It is hypothesised that the observed decrease in the growth rate is related to the mechanical resistance of the oil components adsorbed on the interface to the growth of the hydrate film. The growth rate of the film has been shown to depend on the experimental procedure,most likely due to the different initial concentrations of carbon dioxide in the aqueous solutions.

关键词： Gas hydrate Oil Carbon dioxide Growth rate Hydrate film

Low-temperature processing of screen-printed piezoelectric KNbO3 with integration onto biodegradable paper substrates

在线全文

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2023年第1期9卷 271-282页

作者： Morgan M.Monroe LGuillermo Villanueva Danick Briand École Polytechnique Fédérale de Lausanne(epfl) Soft Transducers LaboratoryInstitute of Mechanical Engineering2000NeuchâtelSwitzerland École Polytechnique Fédérale de Lausanne(epfl) Advanced NEMS LaboratoryInstitute of Mechanical Engineering1015LausanneSwitzerland

The development of fully solution-processed,biodegradable piezoelectrics is a critical step in the development of green electronics towards the worldwide reduction of harmful electronic ***,recent printing processes for piezoelectrics are hindered by the high sintering temperatures required for conventional perovskite fabrication ***,a process was developed to manufacture lead-free printed piezoelectric devices at low temperatures to enable integration with eco-friendly substrates and electrodes.A printable ink was developed for screen printing potassium niobate(KNbO3)piezoelectric layers in microns of thickness at a maximum processing temperature of 120℃ with high *** parallel plate capacitor and cantilever devices were designed and manufactured to assess the quality of this ink and evaluate its physical,dielectric,and piezoelectric characteristics;including a comparison of behaviour between conventional silicon and biodegradable paper *** printed layers were 10.7–11.2μm thick,with acceptable surface roughness values in the range of 0.4-1.1μ*** relative permittivity of the piezoelectric layer was *** poling parameters were optimised for the piezoelectric response,with an average longitudinal piezoelectric coefficient for samples printed on paper substrates measured as d33,eff,paper=13.57±2.84 pC/N;the largest measured value was 18.37 pC/N on paper *** approach to printable biodegradable piezoelectrics opens the way forward for fully solution-processed green piezoelectric devices.

关键词： KNbO3 piezoelectric integration

Systematic experimental study of the temperature dependence of viscosity and rheological behavior of water-based drilling fluids with nano-additives

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum 2023年第4期9卷 534-544页

作者： A.V.Minakov M.I.Pryazhnikov E.I.Mikhienkova Y.O.Voronenkova Siberian Federal University KrasnoyarskRussia Kutateladze Institute of Thermophysics SB RASNovosibirskRussia

The paper presents the results of a systematic study of the influence of nano-additives of various concentrations,average sizes and composition on the temperature dependence of the viscosity and rheological behavior of water-based drilling *** compositions of drilling fluids,such as water suspensions of various clay solutions and gammaxan-based polymer solutions,were *** nanoparticles of silicon and aluminum oxides were used as nano-additives at concentrations ranging from 0.25 to 3 wt%.The average nanoparticle size varied from 10 to 151 *** temperature of drilling fluids varied from 25℃ to 80℃.It is shown that the addition of nanoparticles to drilling fluids leads to a significant change in their rheological properties depending on the *** was found that with increasing temperature,the yield stress and consistency index of drilling fluids with nanoparticles increase,while the behavior index,on the contrary,*** behavior depends on the size of the *** the particle size increases,their influence on the temperature dependence of the drilling fluids’viscosity *** general,it is shown that the addition of nanoparticles makes the viscosity of drilling fluid more stable with regard to the *** is an essential fact for practical application.

关键词： Drilling fluid Nano-additive Viscosity Rheology Temperature

Assessment of the thermal effect of large industrial buildings on permafrost foundation soils in Yakutsk

在线全文

学校读者我要写书评

暂无评论

Research in Cold and Arid Regions 2023年第6期15卷 262-267页

作者： Rudolf V.Zhang Stanislav I.Zabolotnik Pavel S.Zabolotnik Melnikov Permafrost Institute sb RAS Yakutsk 677010Russia

The results of monitoring studies of the ground thermal state beneath the Yakutsk Combined Heat and Power Plant buildings are presented in order to determine their structural stability and the possibility of further troublefree operation of the entire complex of the *** main causes for the formation of water-bearing taliks under and adjacent to the buildings are presented,and the factors influencing the existing geocryological situation are *** continuing stable state of the buildings demonstrates the possibility of using two construction principles on permafrost at one site,including preserving permafrost and accommodating permafrost thawing.

关键词： Yakutsk Combined Heat and Power Plant Permafrost Talik Ground temperature

Insight into the key kinetic steps in the pyrolysis of coking and non-coking coals,characterization of the pyrolysis products

在线全文

学校读者我要写书评

暂无评论

International Journal of Coal Science & Technology 2023年第2期10卷 169-180页

作者： P.N.Kuznetsov O.Yu.Fetisova L.I.Kuznetsova B.Avid B.Purevsuren Institute of Petroleum and Gas Siberian Federal UniversityKrasnoyarskRussia Institute of Chemistry and Chemical Technology sb RAS Federal Research Center"Krasnoyarsk Science Center SB RAS"KrasnoyarskRussia Institute of Chemistry and Chemical Technology Mongolian Academy of SciencesUlaanbaatarMongolia

The chemical composition,structural and plastometric properties of different-ranked coals from Mongolia deposits were *** non-isothermal iso-conversion Ozawa-Flynn-Wall and Friedman model-free methods were used to assess kinetic parameters and to differentiate decomposition *** peculiarities of the pyrolysis kinetics of brown and bituminous coals were revealed and discussed in terms of the composition and plastometric *** coal was shown to undergo three decomposition steps with ever increasing activation energy as temperature increased because of the decomposition of thermally more and more stable molecular *** pyrolysis of bituminous coals occurred in four steps,the activation energy having extreme mode of temperature *** important new finding was that the temperature range of the second,major pyrolysis step well corresponded to that between the softening and re-solidification temperatures according to Gieseler *** yield and composition of the pyrolysis products obtained under isothermal conditions were also characterized depending on coal rank and temperature,and the ways for qualified utilizations were offered.

关键词： Coal Pyrolysis Thermogravimetry Plastometry Activation energy

Hubbard U through polaronic defect states

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 2504-2511页

作者： Stefano Falletta Alfredo Pasquarello Chaire de Simulationàl’Echelle Atomique(CSEA) Ecole Polytechnique Fédérale de Lausanne(EPFL)CH-1015LausanneSwitzerland

Since the preliminary work of Anisimov and co-workers,the Hubbard corrected DFT+U functional has been used for predicting properties of correlated materials by applying on-site effective Coulomb interactions to specific ***,the determination of the Hubbard U parameter has remained under intense discussion despite the multitude of approaches ***,we define a selection criterion based on the use of polaronic defect states for the enforcement of the piecewise linearity of the total energy upon electron occupation.A good agreement with results from piecewise linear hybrid functionals is found for the electronic and structural properties of polarons,including the formation *** values of U determined in this way are found to give a robust description of the polaron energetics upon variation of the considered *** particular,we also address a polaron hopping pathway,finding that the determined value of U leads to accurate energetics without requiring a configurational-dependent *** is emphasized that the selection of U should be based on physical properties directly associated with the orbitals to which U is applied,rather than on more global properties such as band gaps and band *** comparison,we also determine U through a well-established linear-response scheme finding noticeably different values of U and consequently different formation *** origins of these discrepancies are *** case studies,we consider the self-trapped electron in BiVO_(4),the self-trapped hole in MgO,the Li-trapped hole in MgO,and the Al-trapped hole inα-SiO_(2).

关键词： Hubbard polaron piecewise

Accurate and efficient band-gap predictions for metal halide perovskites at finite temperature

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2022年第1期8卷 2267-2279页

作者： Haiyuan Wang Alexey Tal Thomas Bischoff Patrick Gono Alfredo Pasquarello Chaire de Simulationàl’Echelle Atomique(CSEA) Ecole Polytechnique Fédérale de Lausanne(EPFL)LausanneCH-1015Switzerland

We develop a computationally efficient scheme to accurately determine finite-temperature band gaps for metal halide perovskites belonging to the class ABX_(3)(A=Rb,Cs;B=Ge,Sn,Pb;and X=F,Cl,Br,I).First,an initial estimate of the band gap is provided for the ideal crystalline structure through the use of a range-separated hybrid functional,in which the parameters are determined non-empirically from the electron density and the high-frequency dielectric ***,we consider two kinds of band-gap corrections to account for spin-orbit coupling and thermal vibrations including zero-point *** particular,the latter effect is accounted for through the special displacement method,which consists in using a single distorted configuration obtained from the vibrational frequencies and eigenmodes,thereby avoiding lengthy molecular *** sequential consideration of both corrections systematically improves the band gaps,reaching a mean absolute error of 0.17 eV with respect to experimental *** computational efficiency of our scheme stems from the fact that only a single calculation at the hybrid-functional level is required and that it is sufficient to evaluate the corrections at the semilocal level of *** scheme is thus convenient for the screening of large databases of metal halide perovskites,including large-size systems.

关键词： theory. perovskite halide