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Triaxial tension and compression tests on saturated lime-treated plastic clay upon consolidated undrained conditions

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3328-3342页

作者： Kuchvichea Kan Bertrand françois Department of Civil Engineering Institute of Technology of CambodiaPhnom PenhCambodia BATir Department UniversitéLibre de BruxellesBrusselsBelgium ArGEnCo Departement Universitéde LiègeLiègeBelgium

Lime-treatment of clayey soil significantly increases its shear and tensile ***,the tensile strength of lime-treated soils deserves careful investigation because it may provide an appreciable benefit for the stability of earth *** study investigates the tensile and shear strengths of an untreated and lime-treated(3%of lime)plastic clay at different curing times(7 d,56 d and 300 d),through triaxial tension and compression *** tension tests are performed using“diabolo-shaped”soil samples with reduced central section,such that the central part of the specimen can be under axial tension while both end-sections remain in axial *** undrained(CU)conditions with measurement of pore water pressure allow analyzing the failure conditions through effective stress and total stress *** results of triaxial tension tests reveal that the failure occurs under tensile mode at low confining pressure while extensional shear failure mode is observed under higher confining ***,a classical Mohr-Coulomb shear failure criterion must be combined with a cut-off tensile strength criterion that is not affected by the confining *** comparing shear failure under compression and tension,a slight anisotropy is observed.

关键词： Tensile strength Consolidated undrained(CU)triaxial test Lime-treated soils Failure criterion

Influence of the iodide/iodine redox system on the self-discharge of AC/AC electrochemical capacitors in salt aqueous electrolyte

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Progress in Natural Science:Materials International 2015年第6期25卷 622-630页

作者： Qamar Abbas fran?ois Béguin Institute of Chemistry and Technical Electrochemistry Poznan University of Technology

Self-discharge(SD) of AC/AC(AC ? activated carbon) electrochemical capacitors in aqueous solutions of lithium sulfate(Li2SO4) and lithium sulfate t iodide salts(Li2SO4tKI or Li2SO4tLi I) was investigated at 24 1C and 40 1C after cell potential hold at values from 1 V to 1.6 ***24 1C,the cells exhibit lower SD in Li2SO4tKI than in Li2SO4,owing to the redox activity of the 2I /I2 system which drives the positive AC electrode to operate in narrow potential range and display lower potential drop than in *** 401 C,the capacitors exhibit comparable and reduced SD both in Li2SO4tLi I and Li2SO4,whatever the holding cell ***-electrode cell experiments demonstrate that,at 40 1C,hydrogen chemisorption is thermodynamically unfavored under negative polarization,while the activity of the 2I /I2 redox system under positive polarization is only slightly *** a consequence,the AC/AC cells in Li2SO4 exhibit a typical electrical double-layer performance at 401 C,whereas they still behave as hybrid ones in Li2SO4tLi I,with twice higher capacitance than in ***(Ui-Ut) vs t1/2plots demonstrate that SD is essentially controlled by diffusion at 401 C,suggesting that it originates from bulkier hydrated ***,in the investigated temperature range,the AC/AC capacitors in Li2SO4tLi I demonstrate low self-discharge and high capacitance,while being able to operate up to 1.6 V.

关键词： Supercapacitors Activated carbon Self-discharge Salt aqueous electrolyte Iodide/iodine redox system Activation and diffusion controlled mechanisms

Modeling of 3-D Losses and Deviations in a Throughflow Analysis Tool

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Journal of Thermal Science 2007年第3期16卷 208-214页

作者： Jean-fran■ois Simon OlivierLéonard Techspace Aero-Aerodynamic Group University

This contribution is dedicated to the modeling of the end-wall flows in a throughflow model for turbomachinery applications. The throughflow model is based on the Euler or Navier-Stokes equations solved by a Finite-Volume technique. Two approaches are presented for the end-wall modeling. The first one is based on an inviscid formulation with dedicated 3-D distributions of loss coefficient and deviation in the end-wall regions. The second approach is directly based on a viscous formulation with no-slip boundary condition along the annular end-walls and blade force modification in the region close to the end-walls. The throughflow results are compared to a series of 3-D Navier-Stokes calculations averaged in the circumferential direction. These 3-D calculations were performed on the three rotors of a low pressure axial compressor, for a series of tip clearance values.

关键词： throughflow losses deviations axial compressors

Diversity considerations in wideband radar detection of migrating targets in clutter

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Science China(Information Sciences) 2019年第4期62卷 31-40页

作者： franois LE CHEVALIER Nikita PETROV Department Microwave Sensing Signals and Systems (MS3) Delft University of Technology

Wideband radars have been proposed for detection of moving targets, with unique capability of non-ambiguous detection due to range migration. Moreover, frequency diversity has long been used for mitigating the fading effects caused by target and clutter fluctuations. The real benefits of wideband radars are difficult to analyze, since they derive from the combined effects of target resolution in range, migration over successive cells of clutter, Doppler resolution and instantaneous bandwidth, and residual ambiguities in Doppler. In order to contribute to a better understanding of the benefits of agile transmissions for detection of moving targets, clutter cancelling performances of wideband radars are examined, demonstrating clear benefits from diversity on clutter and target, primarily – but not only – obtained through target migration effects. Special attention is given to long-range surveillance and tracking, and new results on detection of moving targets in clutter will be provided to demonstrate the effectiveness of these new architectures for small targets detection at long range, in difficult environments. Finally, recommendations for system designs that improve the discrimination of moving targets against fixed and diffuse clutter are presented.

关键词： radar extended target frequency diversity wideband detection target migration clutter cancelling

One-Dimensional Symmetry and Liouville Type Results for the Fourth Order Allen-Cahn Equation in R^N

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Chinese Annals of Mathematics,Series B 2017年第1期38卷 149-172页

作者： Denis BONHEURE franois HAMEL Département de Mathématique Université libre de Bruxelles INRIA-Team MEPHYSTO Aix Marseille Univ CNRSCentrale Marseille

In this paper, the authors prove an analogue of Gibbons' conjecture for the extended fourth order Allen-Cahn equation in R^N, as well as Liouville type results for some solutions converging to the same value at infinity in a given direction. The authors also prove a priori bounds and further one-dimensional symmetry and rigidity results for semilinear fourth order elliptic equations with more general nonlinearities.

关键词： Fourth order elliptic equation Allen-Cahn equation Extended Fisher-Kolmogorov equation One-dimensional symmetry Liouville type results

Exact Computation of the Topology and Geometric Invariants of the Voronoi Diagram of Spheres in 3D

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Journal of Computer Science & Technology 2013年第2期28卷 255-266页

作者： franois Anton Darka Mioc Marcelo Santos Research Division of Geodesy National Space Institute Technical University of Denmark Department of Geodesy and Geomatics Engineering University of New Brunswick

In this paper, we are addressing the exact the Voronoi diagram of spheres using Wu＇s algorithm. computation of the Delaunay graph （or quasi-triangulation） and Our main contributions are first a methodology for automated derivation of invariants of the Delaunay empty circumsphere predicate for spheres and the Voronoi vertex of four spheres, then the application of this methodology to get all geometrical invariants that intervene in this problem and the exact computation of the Delaunay graph and the Voronoi diagram of spheres. To the best of our knowledge, there does not exist a comprehensive treatment of the exact computation with geometrical invariants of the Delaunay graph and the Voronoi diagram of spheres. Starting from the system of equations defining the zero-dimensional algebraic set of the problem, we are applying Wu＇s algorithm to transform the initial system into an equivalent Wu characteristic （triangular） set. In the corresponding system of algebraic equations, in each polynomial （except the first one）, the variable with higher order from the preceding polynomial has been eliminated （by pseudo-remainder computations） and the last polynomial we obtain is a polynomial of a single variable. By regrouping all the formal coefficients for each monomial in each polynomial, we get polynomials that are invariants for the given problem. We rewrite the original system by replacing the invariant polynomials by new formal coefficients. We repeat the process until all the algebraic relationships （syzygies） between the invariants have been found by applying Wu＇s algorithm on the invariants. Finally, we present an incremental algorithm for the construction of Voronoi diagrams and Delaunay graphs of spheres in 3D and its application to Geodesy.

关键词： Voronoi diagram of spheres Delaunay graph of spheres Wu's method invariant characteristic set

Immunotoxic effects of an industrial waste incineration site on groundwater in rainbow trout (Oncorhynchus mykiss)

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Journal of Environmental Sciences 2014年第5期26卷 981-990页

作者： Nadjet Benchalgo franois Gagn Michel Fournier INRS-Institut Armand-Frappier Emerging Methods Aquatic Contaminant Research Division

The discharge of organic waste from the petrochemical industry into the Mercier lagoons caused major groundwater contamination. The objective of this study was to determine the immunotoxic potential of three groundwater wells at increasing distance from the incinerator dumping site （1.17, 2.74 and 5.40 km）. Rainbow Trout were exposed to increasing concentrations of water from three groundwater wells for 14 days. Immunocompetence was characterized by phagocytosis, mitogen-stimulated proliferation of lymphocytes, cell cycle analysis and apoptosis. A significant increase in innate （phagocytosis） and specific immune response （B lymphocyte proliferation） was observed in trout exposed to water collected from the well at 2.74 km. However, phagocytosis activity was suppressed in groups at 1.17 and 5.40 km. The proportion of lymphocytes in S phase was significantly increased in groups at 2.74 and 5.40 kin, while lymphocytes in G0/G1 phase were decreased in all three exposure groups. Additionally, dexamethasone （DEX）-induced apoptosis of lymphocytes was significantly reduced in the group at 2.74 km, which suggests decreased lymphocyte turnover. Furthermore, the ratio of DEX- induced apoptosis/apoptosis was lower in the groups at 2.74 and 5.40 km. In summary, our experiments have shown that exposure to the mixture of organic compounds present in Mercier groundwater modulates phagocytosis and cell proliferation, disrupts the cell cycle and reduces the ratio of DEX- induced apoptosis/apoptosis. It is concluded that groundwater collected in the vicinity of an incinerator containment field could impact immunocompetence in fish.

关键词： groundwater phagocytosis lymphocyte proliferation cell cycle apoptosis rainbow trout

Gas free oxidation of NaCN for presodiating and stabilizing the anodic host of sodium-ion capacitors

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Journal of Energy Chemistry 2022年第9期31卷 33-40,I0002页

作者： Xuexue Pan Agnieszka Chojnacka françois Béguin Poznan University of Technology Institute of Chemistry and Technical ElectrochemistryBerdychowo 460-965 PoznanPoland

Sodium-ion capacitors(NICs)trigger considerable attention due to their higher specific energy than electrical double-layer capacitors(EDLCs)at comparable specific ***,the presodiation process of the anodic host is extremely crucial for the construction of high-performance ***,a positive EDL electrode containing activated carbon(AC)mixed with sodium cyanide(NaCN)as a sacrificial material was electrochemically oxidized to presodiate a Sn_(4)P_(3) anodic host buffered by hard carbon(HC).The oxidation of CN-occurred ca.2.9 V ***/Na+and finished by a short region of linearly increasing potential with a total capacity close to the theoretical value of 547 mAh g^(-1).The operando electrochemical mass spectrometry(EMS)analysis of the atmosphere in the cell together with the internal pressure measurements realized during the galvanostatic oxidation of a YP80F-NaCN electrode demonstrate that the process occurs without any gas evolution.A precursor cell of an NIC was constructed in a pouch with YP80FNaCN and HC/Sn_(4)P_(3) *** the oxidative sodium transfer from NaCN to HC/Sn_(4)P_(3),the realized YP80F//Nax(HC/Sn_(4)P_(3))NIC demonstrated a discharge capacitance retention higher than 80%for 8900 cycles in the voltage range from 2.0 to 3.8 *** infrared analysis of the anode obtained by the herein described transfer process detected polycyanogen,which stabilizes the electrode structure during cycling,and thereof is at the origin of the enhanced life span of the NIC.

关键词： Na-ion capacitors Activated carbon EDL electrode Sacrificial NaCN HC/Sn_(4)P_(3)anodic host Polycyanogen Anode stabilization

Characterization of Particle Emissions of Turbocharged Direct Injection Gasoline Engine in Transients and Hot Start Conditions

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Journal of Thermal Science 2021年第6期30卷 2056-2070页

作者： Vincent BERTHOME David CHALET Jean-françois HETET Ecole Centrale de Nantes LHEEA Lab.(ECN/CNRS)Nantes 44300France

Reducing pollutant emissions,particularly soot particles emitted by internal combustion engines,is a major challenge for car *** this paper,the experimental setup is a turbocharged three-cylinders gasoline direct injection engine installed on a HORIBA dynamic test driven by a HORIBA STARS *** particle-measuring device is a Pegasor Particles Sensor that measures the current carried by previously electrically charged *** hot engine stabilized tests,with lambda parameter lower or equal to one,have very low emission levels,unlike dynamic *** a consequence,the present paper deals with experiments in transient *** diesel engine,cycle tests show that particulate emissions vary *** understand the phenomenon,a simple transient was created and reproduced a hundred times in order to obtain enough data to analyze and compare these different *** transient starts from idle to reach the speed of 2000 r/min and 60 N·m in 5 *** reach this point,it is necessary to stay in full load for about 3 *** maximum deviations of particles reaches 85%with the standard deviationσ=18%.The cylinder pressure sensor shows significant variations at the very beginning of each transient,i.e.,during the first 500 *** kind of result was observed for Worldwide harmonized Light vehicles Test Cycles(WLTC)with a maximum deviations of particles reaching 75%withσ=30%,on Real Drive Emissions Cycle(RDE)with a maximum deviations of particles reaching 45%withσ=22%and for a 300 s Mini-Cycle with a maximum deviations of particles reaching 70%withσ=17%.The Mini-cycle is made up of the five largest accelerations of the WLTP cycle.A complete analysis highlights the importance of filling the first engine *** depends on the opening speed of the throttle,the position of the crankshaft at the beginning of the transient,and the acceleration of the first ***,the NO_(x) sensor shows very slight variations between each *** a consequence,i

关键词： particles gasoline engine cycle-to-cycle variations transients oil consumption