dinesh tiwari - Academia.edu (original) (raw)
Papers by dinesh tiwari
Pedosphere, 2007
To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the... more To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of A1 ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, A1 adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of A1 above a certain initial A1 concentration (0.1 mmol L-' for kaolinite and 0.3 mmol L-' for the Oxisol). The A1 hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of A1 and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of A1 hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. A1 hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in A1 adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed A13+ in total adsorbed A1 with the increase in soil negative surface charge and eliminated or reduced the acceleration of A1 hydrolysis. Different organic anions inhibited the hydrolysis of A1 in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al. , G . L. 2007. Hydrolysis of aluminum ions in kaolinite and Oxisol suspensions as influenced by organic anions. Pedosphere. 17( 1): 9Ck96.
Pedosphere, 2007
To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the... more To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of A1 ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, A1 adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of A1 above a certain initial A1 concentration (0.1 mmol L-' for kaolinite and 0.3 mmol L-' for the Oxisol). The A1 hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of A1 and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of A1 hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. A1 hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in A1 adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed A13+ in total adsorbed A1 with the increase in soil negative surface charge and eliminated or reduced the acceleration of A1 hydrolysis. Different organic anions inhibited the hydrolysis of A1 in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al. , G . L. 2007. Hydrolysis of aluminum ions in kaolinite and Oxisol suspensions as influenced by organic anions. Pedosphere. 17( 1): 9Ck96.
IEEE Transactions on Electron Devices, 1986
A coupled nonlinear transmission line analysis for second harmonic generation from a traveling-wa... more A coupled nonlinear transmission line analysis for second harmonic generation from a traveling-wave field-effect transistor is presented. In the formulation, three main nonlinearities, namely the Schottky-barrier capacitance, the transconductance and the drainconductance, are considered. The coupled nonlinear differential equations are solved under a weak-coupling approximation with the help of the Weierstrassian elliptical function. It is observed that the second harmonic gain is significant after x/l of about 0.7 (where l is the transverse length of the transistor). After this value of x, the amplitude at second-harmonic level increases sharply and follows almost a square-law behavior. It is found that the output drain conductance emerges as a large contributor to harmonic generation. The possibility of an image gate as drain conductivity modulator or a phase velocity synchronizer is proposed. It is confirmed that traveling-wave MESFETs can also be used as harmonic generators.
IEEE Transactions on Electron Devices, 1987
The feasibility of using a traveling-wave (TW) GaAs MESFET as a frequency doubler for high conver... more The feasibility of using a traveling-wave (TW) GaAs MESFET as a frequency doubler for high conversion efficiency has been experimentally demonstrated by obtaining an efficiency of 16 percent. Transistors were fabricated with large gate width (1000 microns) and connecting pads, at both ends of the gate and drain electrodes. A maximum doubler power of 10 dBm was obtained under optimum bias and circuit conditions. It is shown that the efficiency is maximum when all four ports are suitably terminated by loads for fundamental and second harmonic frequencies. For the FET's investigated, an inductor termination of 4.7 nH at the free drain end was found to produce the main improvement of the overall harmonic gain.
IEEE Transactions on Microwave Theory and Techniques, 1981
ABSTRACT
International Journal of Electronics, 1985
A coupled transmission line analysis for non-linear MESFETs is presented. It includes the importa... more A coupled transmission line analysis for non-linear MESFETs is presented. It includes the important non-linearities of MESFETs such as input capacitance (Cgs), transconductance (gm) and output drain conductance (Ggs). The non-linear differential equation for the drain and gate modes can be solved for a relatively weak coupling approximation using the weierstrassian elliptical function.
IEEE Transactions on Electron Devices, 1987
Abstruct-The feasibility of using a traveling-wave (TW) G a~s MESFET as a frequency doubler for h... more Abstruct-The feasibility of using a traveling-wave (TW) G a~s MESFET as a frequency doubler for high conversion efficiency (7 := Po,, (20) / P d c has been experimentally demonstrated by obtaining 71 := 16 percent. Transistors were fabricated with large gate width (w := 1000 pm) and Connecting pads, at both ends of the gate and drain ellcctrodes. A maximum doubler power of -10 dBm was obtained under optimum bias and circuit conditions. It is shown that the efficiency is maximum when all four ports are suitably terminated by loads for fundamental and second harmonic frequencies. For the FET's invesligated, an inductor termination of 4.7 nH at the free drain end "as found to produce the main improvement of the overall harmonic garm.
IEEE Transactions on Microwave Theory and Techniques, 1981
ABSTRACT
IEEE Transactions on Electron Devices, 1986
Abstract-A coupled nonlinear transmission line analysis for second harmonic generation from a tra... more Abstract-A coupled nonlinear transmission line analysis for second harmonic generation from a traveling-wave field-eff ect transistor is pre-sented. In the formulation, three main nonlinearities, namely the Schottky-barrier capacitance, the transconductance and the ...
Pedosphere, 2007
To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the... more To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of A1 ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, A1 adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of A1 above a certain initial A1 concentration (0.1 mmol L-' for kaolinite and 0.3 mmol L-' for the Oxisol). The A1 hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of A1 and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of A1 hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. A1 hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in A1 adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed A13+ in total adsorbed A1 with the increase in soil negative surface charge and eliminated or reduced the acceleration of A1 hydrolysis. Different organic anions inhibited the hydrolysis of A1 in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al. , G . L. 2007. Hydrolysis of aluminum ions in kaolinite and Oxisol suspensions as influenced by organic anions. Pedosphere. 17( 1): 9Ck96.
Pedosphere, 2007
To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the... more To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of A1 ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, A1 adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of A1 above a certain initial A1 concentration (0.1 mmol L-' for kaolinite and 0.3 mmol L-' for the Oxisol). The A1 hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of A1 and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of A1 hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. A1 hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in A1 adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed A13+ in total adsorbed A1 with the increase in soil negative surface charge and eliminated or reduced the acceleration of A1 hydrolysis. Different organic anions inhibited the hydrolysis of A1 in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al. , G . L. 2007. Hydrolysis of aluminum ions in kaolinite and Oxisol suspensions as influenced by organic anions. Pedosphere. 17( 1): 9Ck96.
IEEE Transactions on Electron Devices, 1986
A coupled nonlinear transmission line analysis for second harmonic generation from a traveling-wa... more A coupled nonlinear transmission line analysis for second harmonic generation from a traveling-wave field-effect transistor is presented. In the formulation, three main nonlinearities, namely the Schottky-barrier capacitance, the transconductance and the drainconductance, are considered. The coupled nonlinear differential equations are solved under a weak-coupling approximation with the help of the Weierstrassian elliptical function. It is observed that the second harmonic gain is significant after x/l of about 0.7 (where l is the transverse length of the transistor). After this value of x, the amplitude at second-harmonic level increases sharply and follows almost a square-law behavior. It is found that the output drain conductance emerges as a large contributor to harmonic generation. The possibility of an image gate as drain conductivity modulator or a phase velocity synchronizer is proposed. It is confirmed that traveling-wave MESFETs can also be used as harmonic generators.
IEEE Transactions on Electron Devices, 1987
The feasibility of using a traveling-wave (TW) GaAs MESFET as a frequency doubler for high conver... more The feasibility of using a traveling-wave (TW) GaAs MESFET as a frequency doubler for high conversion efficiency has been experimentally demonstrated by obtaining an efficiency of 16 percent. Transistors were fabricated with large gate width (1000 microns) and connecting pads, at both ends of the gate and drain electrodes. A maximum doubler power of 10 dBm was obtained under optimum bias and circuit conditions. It is shown that the efficiency is maximum when all four ports are suitably terminated by loads for fundamental and second harmonic frequencies. For the FET's investigated, an inductor termination of 4.7 nH at the free drain end was found to produce the main improvement of the overall harmonic gain.
IEEE Transactions on Microwave Theory and Techniques, 1981
ABSTRACT
International Journal of Electronics, 1985
A coupled transmission line analysis for non-linear MESFETs is presented. It includes the importa... more A coupled transmission line analysis for non-linear MESFETs is presented. It includes the important non-linearities of MESFETs such as input capacitance (Cgs), transconductance (gm) and output drain conductance (Ggs). The non-linear differential equation for the drain and gate modes can be solved for a relatively weak coupling approximation using the weierstrassian elliptical function.
IEEE Transactions on Electron Devices, 1987
Abstruct-The feasibility of using a traveling-wave (TW) G a~s MESFET as a frequency doubler for h... more Abstruct-The feasibility of using a traveling-wave (TW) G a~s MESFET as a frequency doubler for high conversion efficiency (7 := Po,, (20) / P d c has been experimentally demonstrated by obtaining 71 := 16 percent. Transistors were fabricated with large gate width (w := 1000 pm) and Connecting pads, at both ends of the gate and drain ellcctrodes. A maximum doubler power of -10 dBm was obtained under optimum bias and circuit conditions. It is shown that the efficiency is maximum when all four ports are suitably terminated by loads for fundamental and second harmonic frequencies. For the FET's invesligated, an inductor termination of 4.7 nH at the free drain end "as found to produce the main improvement of the overall harmonic garm.
IEEE Transactions on Microwave Theory and Techniques, 1981
ABSTRACT
IEEE Transactions on Electron Devices, 1986
Abstract-A coupled nonlinear transmission line analysis for second harmonic generation from a tra... more Abstract-A coupled nonlinear transmission line analysis for second harmonic generation from a traveling-wave field-eff ect transistor is pre-sented. In the formulation, three main nonlinearities, namely the Schottky-barrier capacitance, the transconductance and the ...