399 research outputs found
Multi-Response Optimization For Industrial Processes
Process optimization is a very important point in modern industry. There are many classical optimization methods, which can be applied when some mathematical conditions are verified. Real situations are not very simple so that classical methods may not succeed in optimizing; as in cases when the optimization has several contradictory objectives (Collette, 2002).
The purpose of this work is to propose an optimization method for industrial processes with multiple inputs and multiple outputs (MIMO), for which the optimization objectives are generally contradictory and for which some objectives are not maximum or minimum but performance criteria.
The first step of this method is modeling each process response by a quadratic model. After
establishing the model, we use a simplified numerical optimization algorithm in order to determine
values of the parameters allowing optimizing the different responses, for MIMO processes. This method will also allow finding optimum target values for multiple inputs single output processes
The influence of humic acids extracted from Chaouia soil on the behavior of transition metal ions and pesticides
   Humic acid (HA) and fulvic acid (FA) exist ubiquitously in environments and have a variety of functional groups, which allow them to complex with metal ions and pesticides. Furthermore, these interactions can not only alter the environmental behavior, but also influence the removal and transportation of those pollutants. The study of the interaction between Cu (II), VO (II) and Mn (II) with HAs provides environmental information on the oxidation states of paramagnetic metals and their mechanisms of binding to humic acids. Electron spin resonance (ESR) study demonstrates that VO (II) and Cu (II) ions are bound with oxygen ligands to HAs, while the Mn (II) complex occurs as [Mn(H2O)6]2+. Additionally, Cu (II) ions are more strongly bound than Mn (II) ions to soil HAs. The effect of the presence of HA on photolysis of Tribenuron-methyl (TRB) and Imazapyr (IMAZ) herbicides in water was studied by irradiation of different mixtures of HA/herbicide (0.5:1 and 1:1 by volume). The obtained results clearly demonstrate that HA substances exhibit a screening effect on the photochemical degradation of the two herbicides. The protective effect of HAs on the TRB and IMAZ degradation could be explained with an inclusion and/or adsorption of the herbicide molecules in the humic matrix
Biological activity of leaves and stems extracts of Artemisia herba-alba from the Oriental region of Morocco and extraction of Cellulose from this plant (isolation, modification and applications)
 Biopolymers are polymers that originate from biological sources. Due to their renewable biodegradability and abundance, they present themselves as a high potential source of innovation for several industrial applications. Polysaccharides, and in particular cellulose, today arouse great interest due to its high abundance, wide distribution, and low cost. It is considered one of the most popular organic polymers and an almost eternal source of raw materials for the growing demand for environmentally eco-friendly materials. First, we evaluated the biological activity (Antioxidant and Antimicrobial) of aqueous and organic extracts of Artemisia herba-alba. Second, we extracted and isolated cellulose from the stems and leaves of this plant. Third, the cellulose was modified to improve its solubility and activity using an acrylamide compound. Finally, we investigated the ability of cellulose acrylate to trap copper(II) ions in water. The objective of the study is to promote and maintain an eco-friendly environment with emphasis on water as a vital source
Study of the effect of chromium on the germination parameters of Fenugreek (Trigonella foenum-gracium L.) and Lens (Lens culinaris)
Received: September 21st, 2022 ; Accepted: January 2nd, 2023 ; Published: February 8th, 2023 ; Correspondence: [email protected] contamination by heavy metals is a global environmental problem. This
contamination affects agricultural crops in the area concerned. In the present study, chromium,
which is a heavy metal, is evaluated for its diverse effects on seed germination and lateral growth
of fenugreek and lens seeds. A chromium solution was prepared at increasing concentrations:
0, 0.02, 0.04, 0.06, 0.08, 0.1, and 0.2 mg L-1 for the addition of germinating seeds in petri dishes
for ten days. After two days, the germination rate is calculated. For the following days the length
of radicle, stem, and number of leaves are measured. The germination rate of fenugreek varies
between 100 and 73.33% for the control and 0.02 mg L-1 of chromium respectively. However,
the germination rate of the lens varies between 100% for the control and 90% for the
0.02 mg L-1
. The elongation of fenugreek radicle with chromium solutions shows a significant
effect. However, there is no significant difference in the lens at the different concentrations. For
the growth of the fenugreek stalk, it is noticed that the concentration 0.02 shows a length of
2.83 cm compared to their control which is 2.30 cm. Consequently, chromium at 0.02 mg L-1
stimulates growth, but at 0.2 mg L-1
, it inhibits it. For lens the length of the stems shows also a
significant difference compared to their control. So the effect of chromium on germination
parameters depends on their concentrations, as well as on the seed response itself. For our
research the response of fenugreek compared to the lens at the same concentrations is different
Severe Tricuspid Valve Endocarditis Related to Tunneled Catheters in Chronic Hemodialysis Patients: When Should the Catheter be Removed?
Introduction: Hemodialysis (HD) patients are predisposed to infective endocarditis (IE) mainly due to repeated manipulation of the vascular access. However, catheter seeding and IE may also result from a distant infection site.Case series: A diabetic patient who was maintained on regular HD through a permanent catheter in the right internal jugular vein presented with septicemia of urinary origin due to Pseudomonas aeruginosa. He was treated with injectable antibiotics for 15 days. Few days after the end of the treatment period he presented with inflammation of the catheter exit site. Blood cultures revealed Pseudomonas aeruginosa and echocardiography showed a large vegetation on the tricuspid valve, confirming the diagnosis of IE. The patient improved after catheter removal and treatment with ceftazidime, vancomycin and amikacin. Another patient who was maintained on chronic HD through a tunneled catheter in the right internal jugular vein presented with a limited infection in the sub-cutaneous tunnel of the catheter that improved after treatment with injectable antibiotics. Two months later, he presented with severe sepsis without signs of local infection of the catheter. Chest radiography showed right sided infiltrates. Injectable antibiotic therapy was given without improvement. Blood cultures were negative but echocardiography showed a large tricuspid valve vegetation. Antibiotic regimen was modified to include vancomycin, amikacin and ceftazidime and the catheter was removed. Unfortunately, the patient died two days after diagnosing IE.Conclusion: catheter seeding and IE may be a consequence of sepsis originating away from the HD catheter site. Tunneled catheters may need to be pre-emptively removed in such situations to prevent serious IE.Keywords: Hemodialysis; Infective Endocarditis; Tricuspid Valv
A Probabilistic Assessment Approach for Wind Turbine-Site Matching
This article provides a new methodology for wind turbine-site matching by using a probabilistic approach. The random behavior of the wind speed climate and the uncertainties of wind turbine characteristics are important to take into account in models used to evaluate the performance of the wind turbine. The proposed formulation of the wind turbine-site matching is derived based on the probabilistic reliability assessment approach. It was experimented using different power curve approximation models, for different random conditions, using time series of wind speed in two sites in Morocco: Dakhla and Essaouira. A comparison based on methods used in literature for the estimation of two-parameter of the Weibull function to fit the wind speed distribution is also carried out. The results revealed that the introduced performance indicators are less sensitive to the models used to approximate the wind power curves compared to the deterministic conventional indicator that leads to different rankings and problems of over-sizing or under-sizing. However, those performance indicators are more sensitive to the variation of the wind speed distribution parameter’s and can help on accurately estimate the wind power. Moreover, the proposed formulation allows a global sensitivity analysis using Sobol’s indices to observe the influence of each input parameter on the observed variances of the performance of a wind turbine. A numerical application illustrates the interpretation of sensitivity indices and shows the impact of the wind speed and the rated wind speed on the variance of the wind turbine performance. This method can help wind energy developers and manufacturers to optimally select WTGs for their future project and accurately forecast the performance of their WTGs for monitoring and maintenance scheduling under uncertainty
Phytochemical study and evaluation of the antioxidant activity of extracts of Opuntia Ficus-Indica cladodes from the Oriental of Morocco and the effect of microwave activation on the drying time of the plant
In the present work, the phytochemical study and evaluation of the antioxidant activities of the crude extracts of various solvents with increasing polarity (ethanol> acetone> dichloromethane > ethyl acetate > hexane) on fine dried cladode powder was studied. Each microwave oven power (500, 350, 160 and 90 W), of an Opuntia ficus-indica (OFI) medicinal species of the Cactaceae family collected in the rural commune of Bni Rais in Taourirt province of Oriental of Morroco. The phytochemical screening showed the presence of the studied chemical compounds (Flavonoids, Tannins, Quinones and Steroids) rich in powers of 500W and 350 W, especially in extracts with ethanol and acetone. The antioxidant activity of OFI cladodes extracts was evaluated by the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging method. The results obtained show that the acetone extracts have a very important activity, especially at the power of 500 W, IC50 = 0.29 mg/ml is found followed by the ethanol extract with a value of IC50 equal to 0.34 mg/ml. After the results we realize that the power 500 W showing antioxidant activity of each solvent extract (Et, Ac, Dc, AE and Hx) greater than that of the power 350, 160 and 90 W respectively (IC50: 500 W <350W <160 W <90 W). Also, the effect of microwaves on the duration of drying of the plant was assessed (40 min under microwave activation compared to 17.5h of conventional heating). The cleaning activities of all extracts, however, were significantly low compared to the reference standard of ascorbic acid with a sequence IC50 = 0.114 mg/ml, used at the same dose
A Bayesian Regularized Artificial Neural Network for Up-Scaling Wind Speed Profile
Maximizing gains from wind energy potential is the principle objective of the wind power sector. Consequently, wind tower size is radically increasing. However, choosing an appropriate wind turbine for a selected site requires having an accurate estimation of vertical wind profile. This is also imperative from the cost and maintenance strategy point of view. Installing tall towers or other expensive devices such as LIDAR or SODAR raises the costs of a wind power project. In this work, we aim to investigate the ability of a Neural Network trained using the Bayesian Regularization technique to estimate wind speed profile up to a height of 100m based on knowledge of wind speed at lower heights. Results show that the proposed approach can achieve satisfactory predictions and prove the suitability of the proposed method for generating wind speed profile and probability distributions based on knowledge of wind speed at lower heights
Paraplégie compliquant une plaie abdominale antérieure par arme blanche
Les traumatismes médullaires sont des complications rares des plaies abdominales antérieures par arme blanche. Son diagnostic est difficile parfoisretardé. L'imagerie par résonance magnétique reste l'examen de choix. Le traitement dépend du tableau clinique et de la gravité de la souffrance médullaire. Le pronostic est corrélé à l'étendue et à la nature de la lésion médullaire. Nous rapportons un cas exceptionnel d'un traumatisme médullaire chez une patiente victime d'une plaie abdominale antérieure par arme blanche
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