This paper is aimed at investigating the nitrogen oxides (NOx=NO+NO2) removal using dielectric barrier discharges (DBD) in a wire-cylinder reactor filled with dielectric pellets and stressed by high pulse voltage. The effects of various parameters (the voltage amplitude, frequency, gas flow rate, and use of the dielectric pellets) on the discharge power and NO/ NOx removal efficiency have been studied experimentally. Two dielectric materials (γ-alumina and glass pellets) were evaluated for their ability to reduce NOx using non-thermal plasma. To improve the NOx removal efficiency, the output of the plasma reactor was pumped into sodium sulfite (Na2 SO3) solution with different concentrations to absorb NO2. It has been found that the discharge power and NO/ NOx removal efficiency increase with the increase of the applied peak voltage and frequency. On the other hand, the discharge power is independent of the gas flow rate, while the NO/ NOx removal efficiency increases with decreasing gas flow rate. The γ-alumina pellets give the best performance for removing both NO and NOx when compared with others due to their ability to oxide NO to NO2 and absorb the resulting NO2. The NOx removal efficiency increases with the increase of the concentration of sodium sulfite solution.

This paper is aimed at investigating the nitrogen oxides (NOx=NO+NO2) removal using dielectric barrier discharges (DBD) in a wire-cylinder reactor filled with dielectric pellets and stressed by high pulse voltage. The effects of various parameters (the voltage amplitude, frequency, gas flow rate, and use of the dielectric pellets) on the discharge power and NO/ NOx removal efficiency have been studied experimentally. Two dielectric materials (γ-alumina and glass pellets) were evaluated for their ability to reduce NOx using non-thermal plasma. To improve the NOx removal efficiency, the output of the plasma reactor was pumped into sodium sulfite (Na2 SO3) solution with different concentrations to absorb NO2. It has been found that the discharge power and NO/ NOx removal efficiency increase with the increase of the applied peak voltage and frequency. On the other hand, the discharge power is independent of the gas flow rate, while the NO/ NOx removal efficiency increases with decreasing gas flow rate. The γ-alumina pellets give the best performance for removing both NO and NOx when compared with others due to their ability to oxide NO to NO2 and absorb the resulting NO2. The NOx removal efficiency increases with the increase of the concentration of sodium sulfite solution.

This paper is aimed at investigating the nitrogen oxides (NOx=NO+NO2) removal using dielectric barrier discharges (DBD) in a wire-cylinder reactor filled with dielectric pellets and stressed by high pulse voltage. The effects of various parameters (the voltage amplitude, frequency, gas flow rate, and use of the dielectric pellets) on the discharge power and NO/ NOx removal efficiency have been studied experimentally. Two dielectric materials (γ-alumina and glass pellets) were evaluated for their ability to reduce NOx using non-thermal plasma. To improve the NOx removal efficiency, the output of the plasma reactor was pumped into sodium sulfite (Na2 SO3) solution with different concentrations to absorb NO2. It has been found that the discharge power and NO/ NOx removal efficiency increase with the increase of the applied peak voltage and frequency. On the other hand, the discharge power is independent of the gas flow rate, while the NO/ NOx removal efficiency increases with decreasing gas flow rate. The γ-alumina pellets give the best performance for removing both NO and NOx when compared with others due to their ability to oxide NO to NO2 and absorb the resulting NO2. The NOx removal efficiency increases with the increase of the concentration of sodium sulfite solution.

This paper is aimed at sizing solar-wind-battery standalone microgrid for supplying irrigation and domestic loads in Toshka area, Toshka, Egypt. Not only the MG system components but also the interconnection cables and feeders are sized. Steady-state power flow through the MG system is analysed at varying sun irradiation and wind speed. Modeling of the MG components and their control of system voltages, currents and powers are investigated. Power flows during different MG operation conditions including absence of wind and sun as well as sudden disconnection of the load are studied.

This paper is aimed at sizing solar-wind-battery standalone microgrid for supplying irrigation and domestic loads in Toshka area, Toshka, Egypt. Not only the MG system components but also the interconnection cables and feeders are sized. Steady-state power flow through the MG system is analysed at varying sun irradiation and wind speed. Modeling of the MG components and their control of system voltages, currents and powers are investigated. Power flows during different MG operation conditions including absence of wind and sun as well as sudden disconnection of the load are studied.

Secondary flows are noxious to axial compressor performance. To overcome and control those secondary flows, vortex generators are used as a passive control device. Controlling secondary flows will lead to a further improvements in the compressor performance. A new design of vortex generator is considered in this investigation in order to control secondary flows in axial compressor cascade at design and off-design conditions. Numerical simulations of a three-dimensional compressible turbulent flow have been performed to explore the effect of the vortex generators on the reduction of secondary flows. Six different incidence angles are used for the off-design operation investigations. Based on the simulation results, the pressure, velocity, and streamline are used to follow up the development of the secondary flows. Thence, total pressure loss coefficient, static pressure rise coefficient, difference in flow deflection angle, and diffusion factor are estimated. Results indicate that vortex generators have a significant effect on the development of secondary flows at off design operation as they cause a reduction in total pressure loss, they also affect the loading behavior of the cascade as they cause a slight change in the cascade deflection, and a slight decrease in the diffusion factor which causes unloading of the blade. Static pressure rise is significantly reduced at negative incidence angles while a slight reduction occurs at positive incidence angles. In a word, the new design of the vortex generator enhances the cascade aerodynamic performance and enlarges the operating range of the cascade towards the positive incidence region.

Secondary flows are noxious to axial compressor performance. To overcome and control those secondary flows, vortex generators are used as a passive control device. Controlling secondary flows will lead to a further improvements in the compressor performance. A new design of vortex generator is considered in this investigation in order to control secondary flows in axial compressor cascade at design and off-design conditions. Numerical simulations of a three-dimensional compressible turbulent flow have been performed to explore the effect of the vortex generators on the reduction of secondary flows. Six different incidence angles are used for the off-design operation investigations. Based on the simulation results, the pressure, velocity, and streamline are used to follow up the development of the secondary flows. Thence, total pressure loss coefficient, static pressure rise coefficient, difference in flow deflection angle, and diffusion factor are estimated. Results indicate that vortex generators have a significant effect on the development of secondary flows at off design operation as they cause a reduction in total pressure loss, they also affect the loading behavior of the cascade as they cause a slight change in the cascade deflection, and a slight decrease in the diffusion factor which causes unloading of the blade. Static pressure rise is significantly reduced at negative incidence angles while a slight reduction occurs at positive incidence angles. In a word, the new design of the vortex generator enhances the cascade aerodynamic performance and enlarges the operating range of the cascade towards the positive incidence region.

Two novel speech coders , called flag modulo pulse code modulation GMPCM and enhansened flag modulo pulse code modulation EGMPCM , are presented. The coders are designed for medium and high bit rate applications. These coders use the modulo PCM principle. A flag bit is used to indicate changing in speech segments. The coders have small modulo amplitude and hence better SNR. Dynamic quantization and bit allocation are also used in these coders in effect these coders function as dynamic quantizers. EGMPCM coders use a new technique to reduce the modulo amplitude by modifying the input speech files. Both coders do not use predictors neither in coding nor in decoding stages. The coders depend only upon the actual difference between conp.

In practical vector quantization (VQ) of images, the used pixel block dimensions are kept small to reduce the cost of computations. This in turn results in highly correlated blocks and the corresponding VQ indices will inherit this high correlation. The compression of the basic VQ can be increased through utilising this high correlation of indices by inserting a lossless index compression stage after the VQ stage. A new index compression algorithm is introduced. In this algorithm the 2 dimensional index map is divided into nonoverlapping square blocks. Index usage in each of these blocks is employed to remap (renumber) the reduced number of actually used indices in this block, thus resulting in reduced bit rate expressed in bits/pixel The proposed algorithm reduces the average bit rate by a value depending on the codebook size, namely a reduction of about 32% for codebook size of 64, and down to about 23% for codebook size of 1024. Moreover this algorithm lends itself to being cascaded by other index compression algorithms resulting in increased compression.

In practical vector quantization (VQ) of images, the used pixel block dimensions are kept small to reduce the cost of computations. This in turn results in highly correlated blocks and the corresponding VQ indices will inherit this high correlation. The compression of the basic VQ can be increased through utilising this high correlation of indices by inserting a lossless index compression stage after the VQ stage. A new index compression algorithm is introduced. In this algorithm the 2 dimensional index map is divided into nonoverlapping square blocks. Index usage in each of these blocks is employed to remap (renumber) the reduced number of actually used indices in this block, thus resulting in reduced bit rate expressed in bits/pixel The proposed algorithm reduces the average bit rate by a value depending on the codebook size, namely a reduction of about 32% for codebook size of 64, and down to about 23% for codebook size of 1024. Moreover this algorithm lends itself to being cascaded by other index compression algorithms resulting in increased compression.