1,601 research outputs found
Fractional Noether's theorem in the Riesz-Caputo sense
We prove a Noether's theorem for fractional variational problems with
Riesz-Caputo derivatives. Both Lagrangian and Hamiltonian formulations are
obtained. Illustrative examples in the fractional context of the calculus of
variations and optimal control are given.Comment: Accepted (25/Jan/2010) for publication in Applied Mathematics and
Computatio
Enhanced removal of Indigo Carmine dye from textile effluent using green cost-efficient nanomaterial: adsorption, kinetics, thermodynamics and mechanisms
Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGThe release of Indigo Carmine in waterbodies may cause serious impact in aquatic ecosystems and human health. There is an interest in developing green, low-cost and effective adsorbents for the removal of toxic dyes from textile effluents. This study proposed the developing of an adsorbent material at the nanoscale using the waste from Moringa oleifera seeds generated after the oil extraction. Moringa oleifera seeds were grounded to obtain an adsorbent material at the nanoscale. Batch-adsorption tests were carried out to evaluate the capacity of the absorbent to retain Indigo Carmine from liquid solutions. The following variables were studied: pH, adsorbent-dye ratio, contact time, initial dye concentration and temperature. The adsorption process fitted the Langmuir isotherm in the equilibrium of adsorption and the power function in the kinetic behavior. The maximum adsorption capacity of the absorbent nanoparticles was 60.24 mg/g, which is 4.3 times higher than that of the bulk Moringa oleifera seeds. Thermodynamic results proved the adsorption process was spontaneous and exothermic. Hydrogen bonding, electrostatic interlinkage and π–π interactions were identified as the dominant mechanisms of Indigo Carmine adsorption on the nanoparticles. The adsorption-desorption study resulted in a slight decrease of the adsorption capacity after 4 cycles, from 94% to 88%. The removal of Indigo Carmine from a textile effluent (85%) was similar to that with pure Indigo Carmine solutions (91%). The results suggested the feasibility of Moringa oleifera seed nanoparticles as a promising, green and low cost adsorbent for textile wastewaters with dyes
Fractional conservation laws in optimal control theory
Using the recent formulation of Noether's theorem for the problems of the
calculus of variations with fractional derivatives, the Lagrange multiplier
technique, and the fractional Euler-Lagrange equations, we prove a Noether-like
theorem to the more general context of the fractional optimal control. As a
corollary, it follows that in the fractional case the autonomous Hamiltonian
does not define anymore a conservation law. Instead, it is proved that the
fractional conservation law adds to the Hamiltonian a new term which depends on
the fractional-order of differentiation, the generalized momentum, and the
fractional derivative of the state variable.Comment: The original publication is available at http://www.springerlink.com
Nonlinear Dynamic
A RESSOCIALIZAÇÃO DO PRESO PELO TRABALHO EM ANÁPOLIS: propostas e soluções
O atual sistema prisional comporta uma definição, ao senso comum, que reforça e faz prevalecer o poder que o Estado tem de fornecer sua sentença condenatória contra aqueles que se desviaram da conduta humana legitimada e que, ao infringirem regras positivas, são julgados, condenados e obrigados a cumprir suas sentenças na intenção de pagar o mal praticado com a pena imposta, sendo, portanto, um sinônimo de castigo e retribuição do Estado
Microalgae production in fresh market wastewater and its utilization as a protein substitute in formulated fish feed for oreochromis spp.
Rapid growing of human population has led to increasing demand of aquaculture production. Oreochromis niloticus or known as tilapia is one of the most globally cultured freshwater fish due to its great adaptation towards extreme environment. Besides, farming of tilapia not only involves small scales farming for local consumption but also larger scales for international market which contributes to a foreign currency earning. Extensive use of fishmeal as feed for fish and for other animals indirectly caused an increasing depletion of the natural resource and may consequently cause economic and environmental unstable. Microalgae biomass seems to be a promising feedstock in aquaculture industry. It can be used for many purposes such as live food for fish larvae and dried microalgae to substitute protein material in fish feed. The microalgae replacement in fish feed formulation as protein alternative seem potentially beneficial for long term aqua-business sustainability. The present chapter discussed the potential of microalgae as an alternative nutrition in fish feed formulations, specifically Tilapia
Recent Development in Antioxidant of Milk and Its Products
Free radicals are produced in humans through natural metabolism or the external environment, such as diet. These free radicals are neutralized by the antioxidant system, whereas enzymes, for example, catalase, superoxide dismutase, and glutathione peroxidase, play an important role in preventing excessive free radicals. Food antioxidants give a good hand in enhancing the human antioxidant system; high consumption of a diet rich in natural antioxidants protects against the risk of diseases such as cardiovascular, cancer, diabetes, and obesity. Milk and its products are popular for a wide range of consumers. Milk contains casein, whey protein, lactoferrin, milk lipid and phospholipids, vitamins, and microelements, for example, selenium (Se), which have antioxidant properties. Furthermore, probiotication of milk either sweet or fermented could enhance the antioxidant capacity of milk. This chapter focuses on presenting recent review data on milk components with antioxidant activity and their health benefits, probiotics as antioxidant agents, and methods for enhancing the antioxidant capacity of dairy products. The key aim of this chapter is to focus on major strategies for enhancing the antioxidant capacity of milk and its products
Application of plastic-damage multidirectional fixed smeared crack model in analysis of RC structures
This paper describes a plasticity-damage multidirectional fixed smeared cracking (PDSC) model to simulate the failure process of concrete and reinforced concrete (RC) structures subjected to different loading paths. The model proposes a unified approach combining a multidirectional fixed smeared crack model to simulate the crack initiation and propagation with a plastic-damage model to account for the inelastic compressive behaviour of concrete between cracks. The smeared crack model considers the possibility of forming several cracks in the same integration point during the cracking process. The plasticity part accounts for the development of irreversible strains and volumetric strain in compression, whereas the strain softening and stiffness degradation of the material under compression are controlled by an isotropic strain base damage model. The theoretical aspects about coupling the fracture, plasticity, and damage components of the model, as well as the model appraisal at both material and structural levels, have been detailed in a former publication. This study briefly summarizes the model formulations, and is mainly dedicated to further explore the potentialities of the proposed constitutive model for the analysis of concrete and RC structures. The model is employed to simulate experimental tests that are governed by nonlinear phenomenon due to simultaneous occurrence of cracking and inelastic deformation in compression. The numerical simulations have predicted with good accuracy the load carrying capacity, ductility, crack pattern, plastic (compressive) zone, and failure modes of all types of structures analysed. The influence of the model parameters that simulate the nonlinear behaviour of concrete under tension and compression is analysed through a parametric study.Portuguese Foundation for Science and Technology in the scope of the SlabSys-HFRC research project, with reference PTDC/ECM/120394/201
Fibre reinforced mortar application for out-of-plane strengthening of schist walls
The aim of the present work is to assess the effectiveness of an innovative strengthening technique for the rehabilitation of masonry buildings deficiently prepared to resist to loading conditions typical of seismic events. This technique is based on the application of outer layers of fibre reinforced mortar (FRM) by spray technology and it is used for increasing the load carrying capacity and deformation ability of masonry elements. For this purpose three almost real scale schist walls prototypes were strengthened and tested. The experimental program is described and the relevant results are presented and discussed. For estimating the properties of the schist walls and FRM taking into account the application conditions, the tested prototypes were simulated with a FEM-based computer program that has constitutive models for the simulation of the nonlinear behaviour of these materials. By using the derived properties, a parametric study was conducted to identify the influence of the FRM properties on the performance of the proposed strengthening system.The author wish to acknowledge CiviTest, Lda (Jesufrei, Portugal) for supporting the experimental program, the sustain provided by INOTEC - Innovative material of ultra-high ductility for the rehabilitation of the built patrimony, QREN project number 23024, and the collaboration of the companies Owens Corning, Exporplas, Sika, Chryso and SECIL for providing, respectively, glass fibres, polypropylene fibres, superplasticizers, Viscous Modifier Agent, and Cement. The authors further wish to acknowledge the Erasmus Plus and Placement Mobility Programs among the University of Ferrara (Italy), the University of Minho (Portugal) and the CiviTest Lda (Portugal) which made this international cooperation possible
CFRP flexural and shear strengthening technique for RC beams : experimental and numerical research
Near surface mounted (NSM) technique has proved to be a very effective
technique for the flexural strengthening of RC beams. Due to the relatively small
thickness of the concrete cover that several beams present, cutting the bottom arm of
steel stirrups for the installation of NSM laminates might be a possible strategy, whose
implications on the beam’s load carrying capacity need to be assessed. When steel
stirrups are cut, however, the shear resistance can be a concern. This also happens
when a strengthening intervention is carried out to increase the flexural resistance of a
beam, since in certain cases it is also necessary to increase the shear resistance in order
to avoid the occurrence of brittle shear failure. The present work assesses the
effectiveness of a technique that aims to increase both the flexural and shear resistance
of RC beams that have the bottom arm of the steel stirrups cut for the application of
NSM laminates. This assessment is performed by experimental and numerical
research. The main results of the experimental program are presented and analyzed,
and the innovative aspects of a constitutive model implemented in a computer program
are described, being their virtues and deficiencies discussed.The study reported in this paper forms a part of the research program "CUTINEMO - Carbon fiber laminates applied according to the near surface mounted technique to increase the flexural resistance to negative moments of continuous reinforced concrete structures" supported by FCT, PTDC/ECM/73099/2006. The authors wish to acknowledge the support also provided by the S&P, Casais and Artecanter Companies. The second Author acknowledges the grant under the aforementioned research project. The third author acknowledges the financial support of FCT, PhD Grant number SFRH/BD/23326/2005
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