Journal for Foundations and Applications of Physics
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Biodiesel production from castor oil and analysis of its physical properties
Get PDFBiodiesel is a biodegradable, renewable energy and efficient substitution fuel which can fulfill energy security needs without sacrificing engine performance. Biodiesel fuels were prepared from vegetable oil of castor beans and its physical properties such as viscosity, flash point and pour point were studied. The crude castor oil was purified and trans-esterified. Transesterification reaction is most widely used method for biodiesel production, in which the triglycerides in the oil reacts with monohydric alcohol. 200 ml of the castor oil was measured and pre-heated to 70 oC using hot magnet stirrer with thermometer. 1.5 ml citric acid was added to the heated oil sample and continuously stirred for 15 minutes at 70 oC. 4g of 8 % KOH was then added to the oil and continuously heated and stirred for 15 minutes at 70 oC. The mixture was then transferred to the vacuum oven where it was heated at 85 oC for 30 minutes. Similarly, 2g of silicon reagent was added while it was being heated and stirred. after 30 minutes the temperature was increased to 85 oC and 4g of activated carbon was added to each 100 ml of the oil sample, heated and stirred for 30 minutes and the mixture was separated using filter paper. At 30, 60 and 90 oC, the viscosity of crude, purified and transesterified castor oil were found to be (64, 52, 50 mpa.s), (47, 43, 37 mpa.s) and (38, 35 and 30 mpa.s) respectively. This shows that, trans-esterified castor oil has viscosities within similar range with the crude biodiesel oil for all the varying temperatures, indicating that viscosity is major reason why oils and fats are trans-esterified to biodiesel
Splitting Frequencies for Resonant Solutions in Central Fields
Get PDFThe behavior of a mass point moving in a plane under the effect of a central field and an ex-ternal periodic excitation in resonance with the natural frequency is studied. The asymptotic perturbation method is used in order to determine the nonlinear modulation equations for the amplitude and the phase of the oscillation. Firstly, we calculate the second order approximate solution of the unforced system. It is well known that generally the solution is two period quasiperiodic, but we find some new cases of periodic solutions. If appropriate Diophantine equations are satisfied, the motion is periodic with a frequency depending on the nonlinear terms. Subsequently, the forced system is considered and external force-response curves are shown and moreover jump phenomena are also observed. In certain cases we observe a frequency splitting and a third frequency appears in addition to the forcing frequency Stable three period quasi-periodic motions are present with amplitudes depending on the initial conditions
Atomic Absorption Spectroscopy Analysis of Heavy metals in water at Daura Gypsum Mining Site, Yobe State, Nigeria
Get PDFThis study was designed to detect heavy metals level in water collected from Daura gypsum mining site, Yobe State, Nigeria. Samples were collected and analyzed using Atomic Absorption Spectroscopy. The level of Pb, Ni, Cd, As, Cu and Zn, were assessed. Also the conductivity of the water samples detected using Conductivity meter. The result shows significant level of As at 0.0382 mg/l, Cd at 0.06-0.18 mg/l and 0.9852 mg/l for Ni which exceeded the WHO limit (0.01 mg/l). Cu, Zn, and Pb were detected at 0.95mg/l, 1.77 mg/l and 0.244 mg/l respectively. Cu, Pb, and Zn were found below the WHO, USEPA limits. This may bring kidney related risk to the people over a long period of time, Therefore, incorporation of ion exchange, reverse osmosis or adsorption in water sources will help reduce the heavy metals burden of the public in the area
Isochronous Behavior and Diophantine Relations for Complex-Valued Nonlinear Systems
Get PDFIsochronous systems are not rare in dynamical systems. Three complex-valued nonlinear systems (quadratic and cubic nonlinearity, van der Pol, gyroscopic oscillator) are investigated by an asymptotic perturbation method based on Fourier expansion and time rescaling. Four coupled equations for the amplitude and the phase of solutions are derived. Approximate solutions are obtained and their stability is discussed. We find that in the first two cases the motion is periodic, while in the third case the motion is periodic only if appropriate Diophantine relations are satisfied. Analytic approximate solutions are checked by numerical integration
Fractal Oscillators
Get PDFWe consider a weakly nonlinear oscillator with a fractal forcing, given by the Weierstrass function, and use the asymptotic perturbation (AP) method to study its behavior. Being this function nowhere differentiable we can only use adequate approximations. We find that while in the linear case the resulting motion is a simple superposition between the fractal forcing and the standard oscillation, on the contrary in the nonlinear case the oscillator phase and its frequency also become fractal. We obtain the Poincarè sections in various cases and all theoretical findings are corroborated with numerical simulation
Jerk Dynamics and Vibration Control for the parametrically excited van der Pol system
Get PDFIn parametrically excited van der Pol system, dangerous vibrations can be controlled and governed by Jerk dynamics. We choose a non-local force for the vibration control and a third or-der nonlinear differential equation (jerk dynamics) is necessary for the control method implementation. Two slow flow equations on the amplitude and phase of the response describe the oscillator motion and we are able to check the control strategy performance. The stability and response of the system is connected to the feedback gains. The dangerous excitations amplitude peak can be reduced adequately picking feedback gains. The new method is successfully checked by numerical simulatio
Vibration Control for Liènard Systems
Get PDFSelf-excitations can be dangerous in many nonlinear systems and can produce catastrophic failures, that is a sudden and complete failure that cannot be put right. We extend the nonlocal vibration control to the suppression of the self-excited vibrations of the Liènard system. We introduce a non local control force that yields a third order non-linear differential equation and use a nonlocal active control to mitigate the amplitude peak in the self-excitations. The nonlocal parameters can be carefully adjusted, in order to avoid undesirable behavior and dynamical nonlinear excitations. We consider the effects of changing the nonlocal parameters on the stability and the value of the response of the system under control. We demonstrate that our method can successfully improve the self-excitation active control, studying a Liènard system through the (AP) asymptotic reduction method. A nonlocal force can be used to suppress self-excitations and put under control the oscillator behavior
Hidden mass and dark matter
Get PDFIt is shown that the substance which is impossible to record in any spectra of electromagnetic radiation, which manifests itself in space only through gravity, cannot be considered a new, previously unknown type of matter – "black matter". The fundamental, unsolvable problems with this approach are demonstrated. The unrecorded substance is a common baryonic substance that makes up the "hidden mass". It has been hypothesized that the bulk of the hidden mass consists of asteroids composed of solid hydrogen. Their formation took place as a result of explosions of the first generation stars (the population III stars) during the gravitational compression of hydrogen clouds in the warm-hot phase, accompanied by self-cooling due to losses associated with electromagnetic radiation. The paper shows at what ratios of physical parameters a similar process is triggered and its physical essence is explained. The possibility of yet another previously unknown direction of spontaneous gravitational compression is shown: compression with self-heating of small mass clouds, resulting in the formation of structures with a degenerate electron gas, including unstable ones. A separate chapter of this work is devoted to a discussion of the problems of the hot Universe model, on which the Big Bang model and the ΛCDM model are based
The Effect of Varying Soot Concentration and Relative Humidity on Visibility and Particle Size Distribution in Urban Atmosphere
Get PDFThis research used extracted extinction coefficients and common mode radii of urban aerosols to carry out visibility simulations at corresponding spectral wavelengths from 0.4-0.8µm from the improved version of the Optical Properties of Aerosols and Clouds (OPAC 4.0) data at eight relative humidities (RH) (0%, 50%, 70%, 80%, 90%, 95%, 98% and 99% RH). Five models of the urban aerosols used comprised of insoluble (INSO), Water-soluble (WASO) and Soot (Black Carbon). From the average concentration set up by OPAC 4.0, the concentrations of the Soot (Black Carbon) were varied by external mixing. The Angstrom exponent (α), the curvature (α2) and the urban atmospheric turbidity (β) were obtained from the regression analysis of the first and second order polynomial of Kaufman’s representation of the Koschmieder equation for atmospheric visibility. The mean exponents of the aerosol size growth curve (µ) were determined from the aerosol effective hygroscopic growth ( ) while the humidification factors (γ) were determined from the visibility enhancement factors f(RH,λ). With µ and γ, the mean exponents of aerosol size distributions (υ) were determined for all the models. It was observed that at varying Soot (Black Carbon) concentrations and RH there were non-linear relationships between them and visibilities. The values of α > 1 showed the presence of fine mode particles from the WASO part of the aerosol mixture and α2 being positive indicated bimodal aerosol particle distributions. Additionally, visibility deterioration is predicted because of the increase in turbidity (β) with the variation of Soot and RH
The formation of a single star planetary system and heat balance of the planets
Get PDFThis paper considers the principles of planetary formation under gravitational compression of a calm, isolated, rarefied gas-dust cloud, different from the compression of a dense gas-dust cloud of a star cluster. The distinctive feature of such compression is the instantaneous formation at a certain stage of the evolution of a gas-dust cloud of a dense, high-energy plasma that makes up a protoplanetary nebula, in which heavy chemical elements are generated. A hypothesis of the scheme of a possible nucleosynthesis is presented. The new conditions for the formation of a protoplanetary cloud, regardless of the hypothesis put forward, entail a fundamentally new concept of planetary evolution. Almost from the very first moments of the formation of a protoplanetary cloud, the proto-nuclei of future planets with their intrinsic magnetic field and complex structure are formed even before the formation of protoplanets. Formed in a same spatial zone within a same process the proto-nuclei are the progenitors of all types of planets of stellar system, i.e., cores are not formed within planets due to gravitational differentiation and high pressure generated by gravitational forces, but rather the planets emerge from proto-nuclei. After a certain, relatively short period of time, the protoplanetary cloud becomes flat and splits into two rings with a gap between them. The type of planet that is formed depends on the place where it is formed. According to physical laws, only young planets can cool down. Therefore, the Earth, which is no longer a young planet, does not cool down