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71.
The aim of this paper is to derive a double LDF non-isothermal model to describe mass transfer through a fixed bed of bi-disperse adsorbent pellets. Firstly, we perform an analysis concerning the different way the composition within the pellets can be described and the consequence on the model structure and compactness. Secondly, we present a bed model including a simplified intra-particle model that is based on a double LDF approximation. This bi-disperse pellet model reduces the number of variables and parameters that are needed. This simplified model is used to simulate breakthroughs of a methane/carbon dioxide mixture over a 5 A zeolite and of a 2,2-dimethylbutane/2-methylpentane mixture over a silicalite molecular sieve. It is also compared with a more detailed model based on Stefan-Maxwell theory that we have previously developed. 相似文献
72.
Gadolinium‐Doped Persistent Nanophosphors as Versatile Tool for Multimodal In Vivo Imaging 下载免费PDF全文
Thomas Maldiney Bich‐Thuy Doan Damien Alloyeau Michel Bessodes Daniel Scherman Cyrille Richard 《Advanced functional materials》2015,25(2):331-338
Recent breakthroughs in the rational development of multifunctional nanocarriers have highlightened the advantage of combining the complementary forces of several imaging modalities into one single nanotool fully dedicated to the biomedical field and diagnosis applications. A novel multimodal optical‐magnetic resonance imaging nanoprobe is introduced. Designed on the basis of a spinel zinc gallate structure doped with trivalent chromium and gadolinium, this nanocrystal bears the ability to serve as both a highly sensitive persistent luminescence nanoprobe for optical imaging, and a negative contrast agent for highly resolved magnetic resonance imaging (MRI). Additional proof is given that surface coverage can be modified in order to obtain stealth nanoparticles highly suitable for real‐time in vivo application in mice, showing delayed reticulo‐endothelial uptake and longer circulation time after systemic injection. 相似文献
73.
Laurène Legrand Sylvain Patinet Jean-Baptiste Leblond Joël Frelat Véronique Lazarus Damien Vandembroucq 《International Journal of Fracture》2011,170(1):67-82
Several groups have studied experimentally the deformation of the front of mode I cracks propagating quasistatically along
the interface between bonded plates. The theoretical interpretation of such experiments has always been based up to now on
a formula of Rice (ASME J Appl Mech 52:571–579, 1985); this formula provides the first-order variation of the local mode I stress intensity factor resulting from some small,
but otherwise arbitrary coplanar perturbation of the front of a semi-infinite crack in an infinite body. To be applicable
to bonded plates, this formula requires that the characteristic distance of variation of this perturbation in the direction
of the crack front be small compared to all other characteristic dimensions of the problem, and first of all the thickness
of the plates. This condition is unfortunately frequently violated in practice. The purpose of this paper is therefore to
provide a more exact formula for the variation of the local stress intensity factor, for the specific cracked geometry and
boundary conditions used in experiments; this should allow for more accurate theoretical interpretations. This is done in
two steps. The first one consists in adapting Rice’s (ASME J Appl Mech 52:571–579, 1985) treatment, applicable to the extreme case of plates of infinite thickness, to the other extreme one of plates of infinitesimal
thickness, using the standard Love-Kirchhoff plate theory. An interesting outcome of the analysis is that the distance from
the crack front to the boundary of the plate acts as a “cutoff length”, in the sense that when the distance between two points
on the crack front gets larger than it, the influence of the crack advance at the first point upon the stress intensity factor
at the second diminishes quickly; the plate thickness, however, plays no similar role. The second step consists in supplementing
the theoretical expressions applicable to extreme values of the plate thickness with finite element computations providing
results for intermediate values. These computations lead to the definition of a simple, approximate but accurate “interpolation
formula” for the variation of the local stress intensity factor, applicable to plates of arbitrary thickness. 相似文献
74.
Water reclamation plants frequently utilise reverse osmosis (RO), generating a concentrated reject stream as a by-product. The concentrate stream contains salts, and dissolved organic compounds, which are recalcitrant to biological treatment, and may have an environmental impact due to colour and embedded nitrogen. In this study, we characterise organic compounds in RO concentrates (ROC) and treated ROC (by coagulation, adsorption, and advanced oxidation) from two full-scale plants, assessing the diversity and treatability of colour and organic compounds containing nitrogen. One of the plants was from a coastal catchment, while the other was inland. Stirred cell membrane fractionation was applied to fractionate the treated ROC, and untreated ROC along with chemical analysis (DOC, DON, COD), colour, and fluorescence excitation-emission matrix (EEM) scans to characterise changes within each fraction. In both streams, the largest fraction contained <1 kDa molecules which were small humic substances, fulvic acids and soluble microbial products (SMPs), as indicated by EEM. Under optimal treatment conditions, alum preferentially removed >10 kDa molecules, with 17-34% of organic compounds as COD. Iron coagulation affected a wider size range, with better removal of organics (41-49% as COD) at the same molar dosage. As with iron, adsorption reduced organics of a broader size range, including organic nitrogen (26-47%). Advanced oxidation (UV/H2O2) was superior for complete decolourisation and provided superior organics removal (50-55% as COD). 相似文献
75.
Early trials and analysis of a new adhesion test are discussed. The test is designed for measuring the adhesion of paint to
deformable steel sheets as used in building, automotive, and other cladding applications, and does not require detailed knowledge
of the paint mechanical properties. A stiff overlay, such as an epoxy resin, is applied to the coating, and the steel substrate
is peeled away using a roll of well-defined radius to which the steel substrate is constrained. The propagation of a crack
within the paint or at some interface in the paint/metal system depends mostly on the mechanical properties and thickness
of the overlay and the radius of the constraining roll. The test is shown to discriminate better than existing practical adhesion
tests between paints of expected differing adhesion/cohesion, but also presents some inconsistencies that require further
work to resolve.
BHP Institute of Steel Processing and Products, Wollongong NSW 2522, Australia. 相似文献
76.
77.
Damien Querlioz Philippe Dollfus Van-Nam Do Arnaud Bournel Van Lien Nguyen 《Journal of Computational Electronics》2006,5(4):443-446
We present an original approach to including quantum transport into classical Ensemble Monte Carlo (EMC) simulations. The
method, based on the Wigner transport equation, is fully self-consistent, and includes impurity and phonon scattering according
to the Fermi Golden rule. It is inspired by an approach suggested by Shifren et al. [IEEE Trans. Electron Dev. 50, 769 (2003)],
with some major improvements that make possible successful comparison with other simulation techniques and experiments. 相似文献
78.
Ricotti Yann Ducret Damien El Guerjouma Rachid Franciosi Patrick 《Mechanics of materials : an international journal》2006,38(12):1143-1158
Measured elasticity moduli of a highly (68%) glass-fiber reinforced epoxy matrix for different amounts of fiber/matrix interface weakening and debonding, due to different hygrothermal ageing stages, are compared to estimated ones. Ultrasonic measurements provide seven of the nine elasticity moduli of the orthotropic material samples, including all the moduli significantly affected by damage. Theoretical estimates combine homogenization modeling techniques and Finite Element (FE) calculations, the latter when the effect of observed partial debonding on effective moduli is to be specified. These estimates are performed under different assumptions for the composite structure, with special attention to the existence of a fiber–matrix interphase. Analytical comparisons for the undamaged composite establish that matching US measurements with estimates cannot be obtained, regardless of the chosen model, without the assumption of an interphase layer of modified resin coating the fibers. This coating resin, when in relevant concentration with regard to literature data about fiber coating thickness, typically conserves the epoxy moduli transversally to the fiber orientation, while, in the fiber direction its moduli approach those of the fibers. The comparison of the US measurements on damaged samples to FE calculations assuming progressive one-directional debonding shows that most of the composite stiffness loss can preferentially be due to an initial interphase weakening, while the fiber/matrix debonding seems more likely delayed to long H-ageing times. This is consistent with physical interpretation of damage by water pooling through silane bridges bonding epoxy to glass. The calculations also provide the effective stiffness, at different damage stages, of the “Undamaged Equivalent Inhomogeneity” for this damaged inclusion type. 相似文献
79.
Radioisotopic cardiac investigation techniques still have a limited role in intensive care units, mainly due to cumbersome traditional equipment, even if in some cases favourable local circumstances exist, such as the proximity of a nuclear medicine unit or the availability of a mobile gamma camera. Nevertheless, nuclear techniques show a number of interesting features, mainly related to the fact that measurements of cardiac chamber volumes and of their variations can be directly derived from activity counts, without any geometrical hypothesis as it is necessary for other methods such as contrast angiography or echocardiography. The whole cardiac cycle (its systolic part as well as its diastolic part) can therefore be evaluated. In addition, since the blood pool labelling remains stable for a long period after a single tracer injection, continuous monitoring of critically ill patients becomes possible. In this case it is no longer the gamma camera imaging system which may be used but rather a very sensitive miniature detector associated with a computerized data acquisition system, allowing beat-by-beat assessment of cardiac activity. The development of this device raises specific problems related to detection geometry, elimination of extracardiac background and stability of the probe positioning on the patient's thorax, but it is clear that such a system merits its place in an intensive care unit in the near future. 相似文献
80.
P. Godin R. Graziotti A. Damien P. Masniere 《International Journal of Hydrogen Energy》1977,2(3):291-297
Corrosion of chrysotile asbestos tissue (diaphragm material) was determined at 115–200°C in pressure vessels (1–20 bars). These tests have shown the good shape of this asbestos material for 2000/h with an unchanged solution of potash at 200°C under a 20 bars pressure, and a progressive elimination of the silica when potash solution is renewed and partial destruction of the samples. 相似文献