A New Approach to the Numerical Solution of Fractional Order Optimal Control Problems

In this article, a new numerical method is proposed for solving a class of fractional order optimal control problems. The fractional derivative is considered in the Caputo sense. This approach is based on a combination of the perturbation homotopy and parameterization methods. The control function u(t) is approximated by polynomial functions with unknown coefficients. This method converts the fractional order optimal control problem to an optimization problem. Numerical results are included to demonstrate the validity and applicability of the method

Optimal control of fredholm integral equations

In this paper a numerical method is proposed for solving optimal control problems governed by Fredholm integral equations (OCF). The method is based upon sinc wavelet and parametrization method and transforms the problem to a nonlinear programming problem. Control function u(t) and state function are approximated by a finite combination of elements of a basis and by a finite combination of sinc wavelet respectively. Numerical examples show the validity and applicability of the proposed method

Influence of zinc incorporation on microstructure of hydroxyapatite to characterize the effect of pH and calcination temperatures

AbstractThis work was focused to study the existence of Zn2+ in structure, chemical composition as well as particle and crystallite size of hydroxyapatite (HAp) to characterize the effect of pH of the solution and calcination temperature. Non-stoichiometric HAp (nHAp) powders containing 4at.% zinc fraction were synthesized via solution–precipitation method. In order to characterize the effect of pH (values: 9 and 10.5) and two calcination temperatures (550 and 1000°C) on chemical composition, molecule internal bonds, particle and crystallite size of the synthesized powders, XRD, EDS, FTIR and SEM techniques were utilized. The results showed that zinc cations could be incorporated in the HAp atomic structure to form low crystalline single phase of nHAP. The pH adjustment to 10.5 caused the formation of powders with smaller particle and crystallite sizes. The results also indicated that calcination temperature up to 1000°C caused decomposition of zinc doped nHAp to β-tri calcium phosphate and tri zinc calcium phosphate phases which are used to control the speed of biodegradation

EFFECT OF RHODIUM INFILTRATION ON THE MICROSTRUCTURE AND PERFORMANCE OF Ni/Ce0.8Gd0.2O2-δ CERMET ANODE FOR LOW TEMPERATURE SOLID OXIDE FUEL CELL

In order to further enhance the Ni/Ce 0.8Gd0.2O2-δ (Ni/GDC20) cermet anodic performance for low temperature solid oxide fuel cell (LT-SOFC), a study was conducted on the nanostructuring of NiO/GDC composite by only once wet-infiltration of rhodium chloride precursor. By using electrochemical impedance spectroscopy (EIS) analysis, the effect of only one drop of Rh-infiltrating solution on the anodic polarization resistance was examined using symmetric Ni–GDC20|GDC20|Pt electrolyte-supported cell at 400-600 °C. Nanostructural evolution before and after H 2 reduction at 600 °C and also after anodic performance test was investigated by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) techniques in comparison to the anode itself. Despite the fine distribution of Rh-infiltrated nanoparticles having average particle size of 11.7 nm, the results showed ineffectiveness and inability of the Rh nanoparticles to succeed in decreasing of anodic polarization resistance for H 2 oxidation reaction in LT-SOFC

Estimation of Urban Suspended Particulate Air Pollution Concentration

A critical eye on the destructive impact of air pollution in Tehran is needed as the basis for urban planning, protection policy and management. This paper is focused on modeling in the GIS (Geospatial Information System) to estimate the concentration of particulate matter (PM) in any point of a typical part of Tehran which extends over 18.2 km2 and includes the so-called “Traffic Zone”. Many important general hospitals are located in this region, some of which are within the zone. The model is built on the data obtained in 42 stations located within the region. The results strongly indicate that the concentrations of PM10, PM2.5 and PM1.0 of any points inside the region, including the traffic zone, do not meet the required international standard values. The extracted estimate values for the 22 hospitals reveal that the concentration of PM10 for “Azadi Psychic”, “Children” and “Mustafa Khomeini” hospitals are the worst, estimating from the model to be 119.42 μg/m3, 107.09 μg/m3 and 101.14 μg/m3 respectively. The percent ratio of the mean concentrations of PM10/ PM2.5/ PM1.0 in this region is found to be approximately 7: 2: 1

Impedance Characteristics of Electrospun Nylon-6/TiO₂ Nanocomposite for Humidity Sensor

Resistive relative humidity (RH) sensors were fabricated by nano composites of nylon-6 and titanium dioxide nanopowders. The results indicated that these sensors can be fabricated as a reliable, low cost and fast response instruments. Different percentages of nylon-6 and TiO2 were studied and average diameters of the resultant nanofibers were found the 80 to 120 nm. The nano composite of nylon-6/TiO nanofibers was electrospun on the interdigital gold electrode on the glass substrate. It was found that the impedance of the mat ranged from 10 Ω to 10 Ω while the relative humidity was increased from 11% RH and 97.3% at room temperature. Transition electron microscopy (TEM) and scanning electron microscopy (SEM) were used to study the morphology of the nano composite

PARTICULATE POLYCYCLIC AROMATIC HYDROCARBONS IN URBAN AIR OF TEHRAN

Polycyclic Aromatic Hydrocarbons are ubiquitous in the urban atmosphere and one of the most atmospheric pollutants to be identified as suspected carcinogens .The objective of this study was to compare particulate PAH profiles from several sites across Tehran. Atmospheric concentrations of Polycyclic Aromatic Hydrocarbons in Tehran were evaluated to study particulate PAH profiles in different sites. The particles size distributions were unimodal with a fine mode diameter (PM<0.49 μm). Five sites were selected in residential areas and one site in rural area for representing various situations and role of motor vehicles in producing Polycyclic Aromatic Hydrocarbons. Organics on the filter were extracted with acetonitrile and a group of 16 Polycyclic Aromatic Hydrocarbons was selected for evaluation. PAH identification was done by High Performance Liquid Chromatography. Total PAH concentration associated with particles collected on the six-stage cascade impactor stages and after-filter in different sites ranged between 0.132 to 234.3 ng/m3. The mean concentrations of Polycyclic Aromatic Hydrocarbons, collected on each stage were: 4.17 ng/m3 for PM10-7.2 μm, 5.69 ng/m3 for PM7.2 - 3 μm, 11.95 ng/m3 for PM3 - 1.5 μm, 9.18 ng/m3 for PM1.5-0.95 μm, 2.82 ng/m3 for PM0.95-0.49 μm and 47.91 ng/m3 for PM < 0.49 μm respectively

Effect of microstructure refinement on performance of Ni/Ce0.8Gd0.2O1.9 anodes for low temperature solid oxide fuel cell

To clarify the role of milling process on polarization resistance of Ni/GDC cermet anodes for low temperature solid oxide fuel cell (LT-SOFC), an anode with the structure of NiO/Ce0.8Gd0.2O2-delta (NiO/GDC20) was prepared Via two different milling processes, including conventional ball-milling (CBM) and high energy ball-milling (HEBM). NiO/GDC20 anode composites were fabricated by screen-printing of the milled powders on the dense sintered GDC electrolyte substrate. By employing electrochemical impedance spectroscopy analysis, the effect of the milling process intensity on the LT-SOFC anode performance was examined using a symmetric Ni-GDC20/GDC20/Pt electrolyte-supported cell at 400-600 degrees C. Microstructural studies of NiO/GDC composite powders showed effectiveness of HEBM method on disintegration of CBM aggregates. HEBM powder with much finer particle size showed smaller crystallites than the CBM powder, which led to a finer-grained uniformly-distributed Ni/GDC anode microstructure. In comparison with the anode prepared by CBM powder, the resulted cermet anode showed further GDC lattice expansion, lower anodic polarization resistance, and also decreased activation energy for hydrogen oxidation reaction. Detailed anode impedance analysis showed dominant role of the charge transfer process and rate determining step of dissociation/adsorption/diffusion in hydrogen-oxidation reaction of both Ni/GDC anodes. In addition, evaluation of activation energy showed enhancement of the charge transfer and dissociation/adsorption/diffusion steps with finer-grained microstructure. It is found that the refinement of microstructure has a significant role on the anode polarization resistance and related electrochemical processes. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.X111816sciescopu

NO2 gas sensor fabrication through AC electrophoretic deposition from electrospun In2O3 nanoribbons

In this paper, electrospinning method was employed to fabricate polymer-ceramic composite fibers from solutions containing polyvinyl pyrrolidone (PVP) and In(NO3)(3)center dot xH(2)O. Upon firing the composite fibers at 600 degrees C, In2O3 nanoribbons with cross section around 250 nm were synthesized. Gas sensor was fabricated by deposition of In2O3 nanoribbons between the electrodes via AC electrophoretic deposition. Gas sensing measurements showed that this material has high response to very low concentrations of NO2 gas at 200 degrees C. (C) 2011 Elsevier BM. All rights reserved