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1.
A unified gas-solid reaction model that considers multi gas-solid components is developed for reactions in porous pellets
with multiple reactants. The transient variables and properties of the reactants and transport parameters are continually
updated in the simulation. Temperature, pressure, solid conversions, and concentration profiles are well predicted. Structural
changes are also considered. Heat, mass, and reaction front tracking equations for all the components are solved simultaneously
through a combination of solution techniques. Illustrative validation results for the model are presented for hematite/nickel
oxide reduction at 608 K. The importance of bulk temperature and pressure on the overall and individual grain conversions
is explored for a range of interest. The response of system parameters to dynamic changes in boundary conditions is studied. 相似文献
2.
This paper is concerned with partial-information mixed optimal stochastic continuous–singular control problem for mean-field stochastic differential equation driven by Teugels martingales and an independent Brownian motion, where the Teugels martingales are a family of pairwise strongly orthonormal martingales associated with Lévy processes. The control variable has two components; the first being absolutely continuous, and the second singular. Partial-information necessary and sufficient conditions of optimal continuous–singular control for these mean-field models are investigated. As an illustration, this paper studies a partial-information linear quadratic control problem of mean-field type involving continuous–singular control. 相似文献
3.
Abba Bala Namata Idouhli Rachid Ilagouma Amadou Tidjani Abouelfida Abdesselam Khadiri MohyEddine Romane Abderrahmane 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(3):619-633
Protection of Metals and Physical Chemistry of Surfaces - In the present study, we evaluated the effect of corrosion inhibition of ethanol extracts from Endostemon tereticaulis and Hyptis spicigera... 相似文献
4.
In this paper, we present a method for robots modeling called bidirectional dynamic modeling. This new method takes into account the gear efficiency and the direction of power transmission in the gears. Epicyclic gearboxes have often different efficiencies in the two directions of power transmission. The characteristics of the chain of transmission must then be taken into consideration in order to describe the dynamic behavior of robots. The two directions of power flow can indeed occur in robot motions. Depending on that direction the dynamic model is different. The bidirectional dynamic modeling is experimentally applied to a bipedal walking robot. Our method exhibits a better accuracy over classical modeling. Moreover, when applied to computed torque control, the bidirectional model increases the tracking performances. 相似文献
5.
The dyeing affinity of some thiazole and benzothiazole basic azo dyes for Leacril 16 acrylic fibre was measured using Langmuir isotherms. Results show a close dependence of dye structure on affinity. 相似文献
6.
7.
A new mathematical model for the transmission dynamics of a disease subject to the quarantine (of latent cases) and isolation (of symptomatic cases) and an imperfect vaccine is designed and analyzed. The model undergoes a backward bifurcation, where a stable disease-free equilibrium co-exists with a stable endemic equilibrium when the associated reproduction threshold is less than unity. It is shown that the backward bifurcation phenomenon can be removed if the vaccine is perfect or if mass action incidence, instead of standard incidence, is used in the model formulation. Further, the model has a unique endemic equilibrium when the threshold quantity exceeds unity. A nonlinear Lyapunov function, of the Goh–Volterra type, is used to show that the endemic equilibrium is globally-asymptotically stable for a special case. Numerical simulations of the model show that the singular use of a quarantine/isolation strategy may lead to the effective disease control (or elimination) if its effectiveness level is at least moderately high enough. The combined use of the quarantine/isolation strategy with a vaccination strategy will eliminate the disease, even for the low efficacy level of the universal strategy considered in this study. It is further shown that the imperfect vaccine could induce a positive or negative population-level impact depending on the size (or sign) of a certain associated epidemiological threshold. 相似文献
8.
Christodoulou Symeon Agathokleous Agathoklis Charalambous Bambos Adamou Aristides 《Water Resources Management》2010,24(13):3715-3730
Sustainable management of urban water distribution networks should include not only new methods for monitoring, repairing
or replacing aging infrastructure, but also (and more importantly) expanded methods for modelling deteriorating infrastructure,
for pro-actively assessing the risk of failure and for devising replace or repair strategies. The study presented herein describes a framework for proactive risk-based integrity monitoring of urban water
distribution networks and the results obtained from a case-study based on a 5-year data sample. A combination of artificial
neural network and statistical modelling techniques stemming from parametric and nonparametric survival analysis (Kaplan–Meier
survival curves with Epanechnikov’s kernel) are utilized in the investigation of identified risk factors and for estimation
of the forecasted time to failure metric. The data is stratified for different pipe groups for a more targeted analysis. 相似文献
9.
From January 1988 to November 1992, 107 (3.5%) of 3074 postneonatal children admitted to the Children's Emergency Room, University of Maiduguri Teaching Hospital, Nigeria, had sporadic pyogenic meningitis; 66 (61.7%) were aged < or = 12 months. Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae together were responsible for 77.3% (58) of 75 culture-proven cases, 13.4% (10) had Enterobacteriaceae, 5.3% (4) had Staphylococcus aureus and 4% (3) untyped alpha-haemolytic streptococci. Fifty percent of 62 bacteria were resistant to ampicillin, 47.2% of 36 to penicillin and 10.7% of 56 to chloramphenicol; none of 21 bacteria was simultaneously resistant to all three antibiotics. Up until 1992, we have encountered treatment failure with a regimen containing chloramphenicol in only 2 of 53 patients; the 2 patients had coliform meningitis. Non-meningococcal bacteria are an important cause of sporadic pyogenic meningitis in sub-Saharan Nigeria and chloramphenicol is the most appropriate initial drug of choice at the present time for the management of sporadic meningitis. 相似文献
10.
Marcia Marie Maru Marcia Maria Lucchese Cristiano Legnani Welber Gianini Quirino Andrea Balbo Isabele Bulhes Aranha Lílian Terezinha Costa Cecília Vilani Lídia gata de Sena Jailton Carreteiro Damasceno Talita dos Santos Cruz Leandro Reis Lidízio Rui Ferreira e Silva Ado Jorio Carlos Alberto Achete 《Fuel Processing Technology》2009,90(9):1175-1182
Compatibility of the new environmentally-friendly alternative of diesel engine fuels, biodiesel, with storage and engine part materials, is still an open issue. In this work, the interaction between three fuels (petroleum diesel and two types of biodiesel — soybean and sunflower) and two materials (carbon steel and high density polyethylene) used in storage and automotive tanks, is analyzed in detail. A wide set of characterization techniques was used to evaluate the changes in both solid and fluid materials, as weight change measurement, optical, scanning electron and atomic force (AFM) microscopies, Raman and FTIR spectroscopies, and differential scanning calorimetry. The AFM technique allowed detecting surface roughness and morphology changes in the metallic material following the trends in the weight losses. In the case of polymeric material, weight gain by fluid absorption occurred, being detected by the spectroscopic techniques. The biodiesel fuels underwent some ageing however this phenomenon did not affect the interaction between the biodiesel fuels and the substrates. The petrodiesel, which did not age, caused more significant degradation of the substrates. 相似文献