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The double loop electrochemical potentiokinetic reactivation (DL-EPR) test using an electrolyte of 33 pct H2SO4 solution with 0.3 pct HCl, at room temperature and at a potential scan rate dE/dt of about 2.5 mV/s, was chosen to evaluate the sensitization of austeno-ferritic duplex stainless steels (DSS). Reproducible
and optimal test responses and high test selectivity in detecting integranular corrosion (IGC) susceptibility were verified
for four DSS differing in their method of fabrication (cast or wrought) and their ferrite phase content (44 to 57 pct). The
test was successfully used to analyze the interactions between precipitation, chromium depletion, and IGC sensitization of
the UNS S31250 steel, which was aged between 6 minutes and 120 hours at temperatures varying from 500 °C to 900 °C. The eutectoid
decomposition of the ferrite, at different aging temperatures, was investigated using various techniques. The chromium depletion
was analyzed qualitatively by X-ray mapping in a scanning transmission electronic microscope (STEM) and quantitatively by
analytical calculation based on the chromium diffusion in the ferrite. It was shown that the chromium content in the ferrite
can decrease from 30 to 7.5 pct by weight during aging before total decomposition occurs. The interactions between precipitation
and IGC sensitization during DSS aging were clearly shown by superimposing the time-temperature-start of precipitation (TTP)
and time-temperature-sensitization (TTS) diagrams obtained from the DL-EPR tests performed for various levels of sensitization. 相似文献
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Wei Kang Mingqing Xiao Amadou Tall I. 《Automatic Control, IEEE Transactions on》2003,48(10):1724-1736
Given a system with an uncontrollable linearization at the origin, we study the controllability of the system at equilibria around the origin. If the uncontrollable mode is nonzero, we prove that the system always has other equilibria around the origin. We also prove that these equilibria are linearly controllable provided a coefficient in the normal form is nonzero. Thus, the system is qualitatively changed from being linearly uncontrollable to linearly controllable when the equilibrium point is moved from the origin to a different one. This is called a bifurcation of controllability. As an application of the bifurcation, systems with a positive uncontrollable mode can be stabilized at a nearby equilibrium point. In the last part of this paper, simple sufficient conditions are proved for local accessibility of systems with an uncontrollable mode. Necessary conditions of controllability and local accessibility are also proved for systems with a convergent normal form. 相似文献
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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
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Cellulase cross‐linked enzyme aggregates (CLEA) activities can be modulated and enhanced by precipitant selection
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The main result of the paper states that almost any analytic single-input control system, which is truly nonlinear, that is not feedback linearizable, with controllable linearization at an equilibrium point, does not admit any symmetry preserving that point. By almost any system, we mean that we exclude a small class of odd systems, that admit just one nontrivial symmetry conjugated to minus identity. The obtained results are based on a recent classification of nonlinear single-input systems under formal feedback. We also describe symmetries of feedback linearizable systems. 相似文献
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Issa Amadou Tall 《International journal of control》2013,86(10):1994-2011
This article discusses the feedback equivalence of multi-inputs feedforward control systems via smooth (resp. analytic) feedback transformations. We first address the state (resp. feedback) linearisation problem, and provide easily computable algorithms that yield explicit state (resp. feedback) linearising coordinates for systems in strict feedforward form. The application of the algorithms does not require checking the commutativity (resp. involutivity) of the distributions associated with the system, and the algorithms fail after few steps if the system is not linearisable. In the latter case, the algorithms are extended to provide coordinate systems bringing the system into a normal form which is a smooth (resp. analytic) counterpart of Kang's formal normal form. Illustrative examples for both the linearisation and convergent normal form include the vertical take off and landing aircraft, the multi-vehicle wireless testbed among others. 相似文献
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Jaouad Bouayed Khosro Piri Hassan Rammal Amadou Dicko Frédéric Desor Chafique Younos Rachid Soulimani 《Food chemistry》2007,104(1):364-368
Medicinal plants are a source for a wide variety of natural antioxidants. In the study reported here, we have conducted a comparative study between five medicinal plants having the same geographic origin: the Hamadan region in the west of Iran and growing in the same natural conditions. The amount of total phenolics and total flavonoids for parts of these plants used in Iranian popular medicine were evaluated. Furthermore, antioxidant activities for these parts using vitamin C equivalent antioxidant capacity (VCEAC) test were also evaluated. The results show that the antioxidant activities varied greatly among the different plant parts used in this study and some plants are rich in natural antioxidants especially leaves of Lavandula officinalis and of Melissa officinalis. A positive correlation between total phenolic or flavonoid contents and VCEAC was found with a correlation coefficient of R2 = 0.961 and R2 = 0.817, respectively. These findings show that phenolics in these plants provide substantial antioxidant activity. 相似文献
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Amadou D. Diop Emil Ceanga Jean-Louis Rtiveau Jean-Franois Mthot Adrian Ilinca 《Renewable Energy》2007,32(13):2268-2290
This paper deals with the methods of three-dimensional fixed-point wind speed real-time simulation modelled in large band, in order to use them in test rigs for experimental investigation of the wind energy conversion systems. The medium- and long-term components of the non-stationary wind speed are considered as known, being issued from measured data or by adopting a generic model. The spectral characteristics of three-dimensional turbulence are described either by the Kaimal or the von Karman models. The turbulence intensity and the length scale that take part in these models are calculated by the site parameters, using current standards. The basic idea of the methods for large-band three-dimensional wind simulation is to use rational shaping filters that approximate non-integer orders shaping filters issued from the Kaimal and the von Karman models. All the synthesized rational shaping filters use one time constant, automatically adapted to the medium- and long-term components that pilot the other time constants of the shaping filters by a set of parameters practically constant. Some numerical results concerning time series that simulate the non-stationary wind speed with three-dimensional turbulence components based on Kaimal and von Karman models are presented. 相似文献