Cunha H.N.,Center for Strategic Research |
Silva F.L.A.J.,Center for Strategic Research |
Melo J.,Center for Strategic Research |
Cavalcanti E.H.S.,National Institute of Science |
And 6 more authors.
Fuel Processing Technology | Year: 2011
The interaction of ozone with bio-fuel has been investigated. The highly reactive gas promotes accelerated oxidation, along with changes of the electrical conductivity. The materials specific parameter is monitored by a specially designed thin-film resistor sensor, integrated within a micro-fluidic flow cell. Recordings of the ozone induced conductivity (OiC) are presented for bio-diesel samples, processed from cotton seed oil, blended with and without antioxidants, as well as for fuel grade ethanol, and for commercial Petrol-Diesel, serving as a reference. The time delay between onset of ozone induced oxidation and associated increase in the electrical conductivity defines the oxidative stability, usually revealing a time span, ranging from minutes to hours. For comparison, Rancimat tests have been performed for the same samples. Comparable induction times were obtained for the OiC method under low ozone flux conditions. The set-up is an easy to implement proposed test method, and allows for electronic on-line fuel quality monitoring. © 2011 Elsevier B.V. All rights reserved.
Neff H.F.,Federal University of Campina Grande |
Neff H.F.,Center for Strategic Research |
Lima A.M.N.,Federal University of Campina Grande |
Melcher E.U.K.,Center for Strategic Research |
And 4 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2010
A dielectric breakdown model, linked to appearance of a singularity, has been developed and applied to a high purity alkane type (n-C36H 74) insulator. The polymer material, which exhibits low defect / trap density, represents the single-crystalline iso-electronic analog to polyethylene. At high fields, and based on experimental findings, carrier transport is mediated by delocalized states in the conduction and valence band, respectively. Field induced impact ionization and carrier multiplication are triggered by hot carrier photoinjection above a critical field magnitude of 0.8 MV for holes and 1.26 MV for electrons, in accord with the band model. Associated critical sample thickness values have been estimated. The related electrical properties have been explored on the basis of the electrothermal heat balance equation. The non-linear differential equation has been solved numerically, with appropriate thermo-physical materials and carrier transport parameters, considering the dielectric breakdown phenomenon as a singularity. It leads to thermal run-away as a consequence of strong positive electro-thermal feedback, under conditions of initial transient behavior. Required thermo-physical parameters are attributed to and explain filamentary charge transport. The temporal evolution of temperature and current in the conducting filament during the breakdown event exhibits a time scale up to the microsecond range. The dynamic properties of the phenomenon are strongly affected by heat transfer from the conducting section into the surrounding nonconducting material, as well as the temporal characteristics of the initial trigger conditions. © 2006 IEEE.
Mirahsani Z.,University of Tehran |
Assari A.,University of Tehran |
Nobakht M.B.,Center for Strategic Research |
Agheli L.,University of Tehran
International Journal of Economic Research | Year: 2015
This study was an attempt to address the function of pharmaceutical production and its features in Iran especially in terms of scale economies. It also studied the status of using the production inputs of pharmaceutical companies in Iran in terms of efficiency. To examine these, the production function was estimated in the country's pharmaceutical industry with the new economic theories using the statistical data of pharmaceutical manufacturers. The main elements of production and the effect of using each one in pharmaceutical production were determined. To estimate the model, a nonhomogeneous production function was used which was a particular type of quadratic logarithm and the CobbDouglas generalized model. This model consisted of the natural logarithm of pharmaceutical production as an endogenous variable and the natural logarithm of two independent variables as function inputs. Further, the data of 21 manufacturing plants were collected from the Food and Drug Administration. The results of the estimation revealed that the pharmaceutical production function in the pharmaceutical manufacturing companies in Iran have an increasing returns to scale. It might also be stated that the marginal production of labor (MPL), the elasticity of labor (EL), the marginal production of production lines (MPP) deployment, and the elasticity of production to the number of production lines (EP) is negative. © 2015 Serials Publications.