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排序方式: 共有93条查询结果,搜索用时 15 毫秒
1.
The electronics industry generates large amounts of fluoride-containing effluents. The objective of this studyis to study the feasibility of applying reverse osmosis (RO) membrane separation to reduce fluoride load to less than 1 kg/d. The effect of transmembrane pressure on the removal of fluoride ion has been investigated in detail, and the design parameters of a small RO separation unit were estimated. The present study indicated that the rejection of fluoride ion is typically higher than 98%, considering that the RO membrane was fully regenerated after each set of experiments. The effect of upstream concentration on the required mechanical pressure was determined by estimating the theoretical osmotic pressure of the feed solution. For industrial effluents, the process developed in this work allows us to reduce the treated volume from 6 m3/d to 0.36 m3/d without any pretreatment or adding additional compounds. The cost of the designed RO separation plant (€76,000) is much less than that of the conventional treatment (€533/m3) that deals mainly with volumes rather than specific 相似文献
2.
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
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.
Data gathered from energy audits, phone surveys and smart meter readings are used to derive regression models of the electricity consumption of housing units in Oshawa (Ontario, Canada). The database used comprises 59 predictors, for 62 observations. To address the problem of multi-collinearities among the predictors and at the same time reduce the number of needed predictors, a methodology is developed based on the latent root regression technique of Hawkins [5]. Contrary to other variable selection techniques such as the stepwise method, the technique used in this paper allows an easy identification of alternative subsets. Using this technique, a reduction of 85% in the number of predictors is obtained, leaving only nine of them in the final subset. These nine variables are the number of occupants, the house status (owned or rented), the number of weeks of vacation per year, the type of fuel used in the pool heater, the type of fuel used in the heating system, the type of fuel used in the domestic hot water heater, the existence or not of an air conditioning system, the type of air conditioning system, and the number of air changes per hour at 50 Pa. A regression with these nine predictors leads to an R2 of 0.79, with an adjusted R2 of 0.75 and all regression coefficients statistically significant at the 95% confidence level. 相似文献
5.
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
6.
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
7.
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
8.
The effects of 18 years continuous cropping of irrigated rice on soil and yields were studied in two long-term fertility experiments
(LTFE) at Ndiaye and Fanaye in the Senegal River Valley (West Africa). Rice was planted twice in a year during the hot dry
season (HDS) and wet season (WS) with different fertilizer treatments. Soil organic carbon (SOC) under fallow varied from
7.1 g kg−1 at Fanaye to 11.0 g kg−1 at Ndiaye. Rice cropping maintained and increased SOC at Ndiaye and Fanaye, respectively and fertilizer treatments did not
affect SOC. Soil available P and exchangeable K were maintained or increased with long-term application of NPK fertilizers.
Without any fertilizer, yields decreased by 60 kg ha−1 (1.5%) and 115 kg ha−1 (3%) per year at Fanaye and Ndiaye, respectively. The highest annual yield decreases of 268 kg ha−1 (3.6%) and 277 kg ha−1 (4.1%) were observed at Fanaye and Ndiaye, respectively when only N fertilizer was applied. Rice yields were only maintained
with NPK fertilizers supplying at least 60 kg N, 26 kg P and 50 kg K ha−1. It was concluded that the double cropping of irrigated rice does not decrease SOC and the application of the recommended
doses of NPK fertilizer maintained rice yields for 18 years. 相似文献
9.
10.
J. Miralles E. Bassene E. M. Gaydou P. J. L. Bourreil F. Ndiaye J. Rasoarahona J. M. Kornprobst 《European Journal of Lipid Science and Technology》1994,96(2):64-66
The seeds of Parinarium excelsum and P. macrophyllum (Rosaceae or Chrysobalanaceae) yield about 65-66% of oil. 13C NMR and gas chromatographic analyses show that these two oils have a high content in α-eleostearic acid, about 62% for P. excelsum and 33% for P. macrophyllum. These results indicate that α-eleosteatic acid can be used as chemotaxonomic tracer and are in agreement, from a chemical point of view, with authors which consider that Chrysobalanaceae constitute a family different from Rosaceae. 相似文献