Cumulant-based LP method for two-dimensional spectral estimation

A cumulant-based linear prediction (CBLP) method for two-dimensional (2-D) spectral estimation is presented. The main idea of the method is to compute the coefficients of two different single-quadrant prediction filters by applying the LP theory to a selected 2-D fourth-order mixed cumulant slice of the noisy signal. These coefficients are employed in formulating two different autoregressive spectral models. Both spectral models are combined to obtain the desired spectral estimate. The effectiveness of the proposed CBLP method is demonstrated through computer simulation     

Higher order statistics based IIR notch filtering scheme forenhancing sinusoids in coloured noise

It is known that sinusoids generate lines in their spectra, but false lines may appear when the sinusoids are corrupted by coloured additive noise. In the paper, a higher-order statistics-based IIR filtering scheme is suggested to suppress additive coloured noise, thus enhancing the desired spectral peaks due to the sinusoids. The filter used is an unknown pole-zero constrained IIR notch filter. The filter coefficients are estimated by applying the linear prediction (LP) method to a block of a fourth-order mixed cumulant slice (FOMCS) of the input noisy signal. Therefore, the presented scheme automatically handles Gaussian noise (white or coloured). In the non-Gaussian noise case, a novel analysis is presented to show that, associated with the FOMCS, there is a new signal-to-noise ratio called the `signal-to-noise kurtosis ratio' (SNKR). This SNKR is a multiple of the conventional SNR if the additive noise is coloured non-Gaussian. Thus, the presented scheme is capable of handling additive coloured noise (Gaussian or non-Gaussian). The performance of the proposed scheme, compared with a correlation-based counterpart, is demonstrated through computer simulations     

System identification using discrete orthogonal functions

In this paper a novel method is described for the design of adaptive IIR filters used in system identification. the adaptive filter is implemented as a parallel connection of subsections whose transfer functions constitute a set of discrete orthogonal systems. the adaptation algorithm used, which is of the Gauss-Newton type, adjusts the parameters of these discrete orthogonal systems in order to match the desired output data of the unknown plant in a least squares sense. Owing to the orthogonality property, which ensures complete independence of subsequent sections, convergence is very rapid. Closed-form expressions for the gradient signals required to update the filter are given. Illustrative examples have shown that this method always results in much improved adaptation properties compared with the already existing approaches.     

STABILITY AND RHEOLOGY OF HEAVY CRUDE OIL-IN-WATER EMULSION STABILIZED BY AN ANIONIC- NONIONIC SURFACTANT MIXTURE

The stability and rheology of an Egyptian Heavy crude oil-in-water emulsions stabilized by an anionic (TDS) and a nonionic (NPE) surfactants individually or in a mixture have been studied. The study reveals that, the viscosity of the crude oil decreases when it is emulsified with water in the form of an oil-in-water type of emulsion. The stability of the oil-in-water emulsion increases as the surfactant concentration and speed of mixing of the emulsion increases. Fresh water and synthetic formation water have been used to study the effect of aqueous phase salinity on the stability and viscosity of the emulsion. Surfactant dissolved in synthetic formation water has been utilized to find out the possibility of injecting the surfactant into a well bore to effect emulsification in the pump or tubing for enhancing the production of heavy crude oils as oil-in-water emulsion. The study revealed that, the viscosity of the emulsion containing fresh water is always less than that containing formation water, these findings have been correlated with the crude oil/water interracial tension (IFT) measurements The decreased IFT value results in a decrease in the average particle size of the dispersed crude oil leading     

LIQUEFACTION OF CELLULOSIC WASTE V. WATER FORMATION AND EVALUATION OF PYROLYTIC CHAR AS A BY —PRODUCT OF PYROLYSIS REACTION

ABSTRACT

Liquid hydrocarbon oil and water have been produced from the liquefaction of cellulosic matter present in municipal solid wastes (MSW). Gases and residual char have also been produced as by-products resulting from the pyrolysis reaction of cellulose. Quantities of water and pyrolytic char were estimated at different conditions of the process (temperature pressure of hydrogen, carrier oil medium and concentration of boric acid). From the results obtained, it was suggested that the formation of water seems to be sensitive to the operational conditions which enhance a water-gas shift reaction (in which water molecules are consumed to produce carbon dioxide and hydrogen). Decreasing of the undesired chary by-product could be achieved by increasing the concentration of boric acid that catalyzes the liquefaction reaction. Two petroleum distillates, namely gas oil and residual fuel oil, were used as carrier media of a solid refuse. It was found that fuel oil is more efficient as a buffering medium that prevents cellulose macromolecules from a rapid and complete charing during the liquefaction process. The pyrolytic char was characterized and evaluated by means of different analytical procedures and solvent extraction using petroleum ether 40–60°C and methanol. Calorific value of the pyrolytic char was found to be 4.6 Kcal g^?1 which is quite close to that of a brown coal. Dropping point test of the extracted material by petroleum ether indicated that the extract can be utilized for producing lubricating greases via saponificattion with a salt of sodium or calcium.     

LIQUEFACTION OF CELLULOSIC WASTE V. WATER FORMATION AND EVALUATION OF PYROLYTIC CHAR AS A BY —PRODUCT OF PYROLYSIS REACTION

Liquid hydrocarbon oil and water have been produced from the liquefaction of cellulosic matter present in municipal solid wastes (MSW). Gases and residual char have also been produced as by-products resulting from the pyrolysis reaction of cellulose. Quantities of water and pyrolytic char were estimated at different conditions of the process (temperature pressure of hydrogen, carrier oil medium and concentration of boric acid). From the results obtained, it was suggested that the formation of water seems to be sensitive to the operational conditions which enhance a water-gas shift reaction (in which water molecules are consumed to produce carbon dioxide and hydrogen). Decreasing of the undesired chary by-product could be achieved by increasing the concentration of boric acid that catalyzes the liquefaction reaction. Two petroleum distillates, namely gas oil and residual fuel oil, were used as carrier media of a solid refuse. It was found that fuel oil is more efficient as a buffering medium that prevents cellulose macromolecules from a rapid and complete charing during the liquefaction process. The pyrolytic char was characterized and evaluated by means of different analytical procedures and solvent extraction using petroleum ether 40-60°C and methanol. Calorific value of the pyrolytic char was found to be 4.6 Kcal g^-1 which is quite close to that of a brown coal. Dropping point test of the extracted material by petroleum ether indicated that the extract can be utilized for producing lubricating greases via saponificattion with a salt of sodium or calcium.     

One-pot green synthesis of magnesium oxide nanoparticles using Penicillium chrysogenum melanin pigment and gamma rays with antimicrobial activity against multidrug-resistant microbes

Melanin pigment is well-known as a common photo-protective polymer, insoluble in water. It drews considerable attention for many applications in nanotechnology, and medical fields. Penicillium chrysogenum was employed for the green synthesis of melanin after optimizing the media compositions. A method has been designed that included one-step synthesis of magnesium oxide nanoparticles (MgO NPs) by fungal melanin under the influence of different doses of gamma rays. Antimicrobial activity of MgO NPs was examined against some selected highly pathogenic microbes. The fungal melanin acted simultaneously as a photo-protector of the magnesium atom, and at the same time as a stabilizer towards the uncontrolled free radical attack resulting from gamma rays. Afterwards, gamma rays forced a condensation reaction to occur at room temperature. A proposed reaction mechanism for MgO NPs synthesis was discussed. MgO NPs were characterized and structurally identified by UV–Vis., XRD, DLS, TEM and FTIR. Results obtained from DLS and XRD with TEM images determined the mean diameter as 10.28?nm. In addition, MgO NPs were found to be promising antimicrobial agents against' Enterococcus faecalis, Candida albicans, and Klebsiella pneumoniae having activity of 22.0, 20.0, and 20.0?mm ZOI, respectively. Based on the capability of MgO NPs as effective antimicrobial agents, they possess a potential role – in different applications such as biomedicine, food control, pharmaceutics, and cosmetics.     

Loss mechanisms in piezoceramic materials

The scope of the paper is the experimental determined of the quality factor near resonance and anti-resonance frequencies for a six unloaded unclamped piezoceramic plates (PZT5-H) samples. The electromechanical coupling coefficient (EMCC) of the samples are predicted using theoretical approach. The total losses tangent factor of the plate’s materials PZT-5H was estimated from the variation of driving point electrical impedance over the interested frequency band rather than the sensitivity of each plate within this band. Experiments are conducted to verify the theoretical results with good agreement. dependence of the resonant and ant resonant frequencies and the electromechanical-coupling coefficient on the relative size of plate is analyzed. These results suggest that driving piezoelectric devices at anti-resonance mode may be an alternative in order to get improved efficiency in piezo device operation.     

Liquefaction of cellulosic wastes: III. Production,characterization and evaluation of pyrolytic oils

Liquefaction of municipal solid wastes has been achieved in an atmosphere of hydrogen gas and in the presence of boric acid which catalyzes the pyrolysis reaction. Two petroleum distillates, namely gas oil and residual fuel oil, were used as carrier media of solid refuse. The yield of pyrolytic oil was studied as a function of different operational conditions (temperature, pressure of hydrogen, carrier oil medium and concentration of boric acid). Hydrocarbon constituents of the oil mixtures, produced by liquefaction of cellulosic wastes slurried in fuel oil, were investigated by means of gas chromatography. It was found that the oil mixture, obtained at optimum reaction conditions, showed pronounced occurrence of low hydrocarbons in the range C₃-C₁₅ as compared with the original fuel oil and the oil resulting from the pyrolysis of carrier oil without solid refuse. The residual pyrolytic char exhibited catalytic activity towards hydrocracking. It was suggested that the activity of char is due to the presence of transition metals as evidenced by an electron dispersion system (EDS). The hydrocracking activity of char seemed to be dependent on the operational conditions of the liquefaction. Multiple analytical parameters including API gravity, calorific value, total acid number and wt% of residue over 450°C were used to evaluate the oil mixtures produced as a petroleum crude oil. Carrier oils, particularly fuel oil, seemed to be highly modified in the course of the pyrolysis process. Also, the oil mixtures produced were distinguished from the original carrier oils by a considerably higher acidity due to association with oxygenated compounds which could be derived from cellulose macromolecules.     

C-means clustering fuzzified by two membership relative entropy functions approach incorporating local data information for noisy image segmentation

In this paper, C-means algorithm is fuzzified and regularized by incorporating both local data and membership information. The local membership information is incorporated via two membership relative entropy (MRE) functions. These MRE functions measure the information proximity of the membership function of each pixel to the membership average in the immediate spatial neighborhood. Then minimizing these MRE functions pushes the membership function of a pixel toward its average in the pixel vicinity. The resulting algorithm is called the Local Membership Relative Entropy based FCM (LMREFCM). The local data information is incorporated into the LMREFCM algorithm by adding to the standard distance a weighted distance computed from the locally smoothed data. The final resulting algorithm, called the Local Data and Membership Relative Entropy based FCM (LDMREFCM), assigns a pixel to the cluster more likely existing in its immediate neighborhoods. This provides noise immunity and results in clustered images with piecewise homogeneous regions. Simulation results of segmentation of synthetic and real-world noisy images are presented to compare the performance of the proposed LMREFCM and LDMREFCM algorithms with several FCM-related algorithms.