Anis Azhari - Academia.edu (original) (raw)
Papers by Anis Azhari
International Journal of Sustainable Energy, 2011
Jatropha curcas alkyl ester can be produced via a transesterification reaction of J. curcas trigl... more Jatropha curcas alkyl ester can be produced via a transesterification reaction of J. curcas triglyceride (JCT) using an alkaline catalyst with an alcohol. In this study, the reaction was carried out in a batch reactor under various operating conditions. The kinetics study of the transesterification of JCT with methanol was conducted at various temperatures ranging from 50 °C to 65 °C. The conversion of triglyceride (TG) and diglyceride (DG) into biodiesel followed a first-order mechanism, while the conversion of monoglyceride into biodiesel occurred too fast, thus assuming a non-limiting step. The reaction rate constants were determined and then plotted against temperatures for the determination of activation energies. The values of k TG ranged from 0.11 to 0.17 min−1 and the values of k DG ranged from 0.07 to 0.20 min−1. The activation energies for the transesterification of TG/DG with methanol were 27.38 and 46.72 kJ mol−1, respectively. The high E a values indicate that the transesterification of J. curcas is sensitive to temperature changes.
Applied Mathematical Modelling, 2009
A solution for the elastic and inelastic local buckling of flat rectangular plates with centerlin... more A solution for the elastic and inelastic local buckling of flat rectangular plates with centerline boundary conditions subjected to non-uniform in-plane compression and shear stress is presented. The loaded edges are simply supported, the longitudinal edges may have any boundary conditions and the centerline is simply supported with a variable rotational stiffness. The Galerkin method, an effective method for solving differential equations, is applied to establish an eigenvalue problem. In order to obtain plate buckling coefficients, combined trigonometric and polynomial functions that satisfy the boundary conditions are used. The method is programmed, and several numerical examples including elastic and inelastic local buckling, are presented to illustrate the scope and efficacy of the procedure. The variation of buckling coefficients with aspect ratio is presented for various stress gradient ratios. The solution is applicable to stiffened plates and the flange of the I-shaped beams that are subjected to biaxial bending or combined flexure and torsion and shear stresses, and is important to estimate the reduction in elastic buckling capacity due to stress gradient.
Abstract The objective of this paper is to provide technical background and illustrative examples... more Abstract The objective of this paper is to provide technical background and illustrative examples for stability analysis of cold-formed steel members using the conventional and constrained finite strip methods as implemented in the open source program CUFSM. ...
A computer-based algorithm that localizes sounds in near-real time has been developed. The algori... more A computer-based algorithm that localizes sounds in near-real time has been developed. The algorithm takes input from two microphones and estimates the position of the sound source relative to the microphone array. The algorithm requires no a priori knowledge of the stimuli to be localized. The accuracy of the algorithm was tested using binaural recordings from a pair of microphones mounted in the ear canals of an acoustic mannequin. Sounds were played at 5 degree steps around the mannequin and the outputs were recorded at the entrance to each ear canal. These recordings were fed into the algorithm that estimated the location of the incoming sound on the horizontal plane. The algorithm utilizes a Head-Related Transfer Function (HRTF) to estimate the location of incoming sound stimuli. Although the HRTF of the acoustic mannequin was used, any HRTF can be inserted into the algorithm, allowing for predictions about individual performance differences. The results of this effort have been highly encouraging: the algorithm was able to identify accurately the location of a variety of sounds, committing an average of 2.9 degrees of unsigned localization error. Better than chance performance was found in noisy conditions of up to a -10 dB signal-tonoise ratio. The initial purpose of this algorithm is to predict the localization performance afforded by different types of combat helmets. Current and future encapsulating helmet designs are likely to impede localization performance, and an accurate localization model would be an invaluable tool in the helmet selection process. Adapting the model for use as a highly accurate machine-based localizer is an additional goal of this line of research. Applications for this technology include target tracking on unmanned vehicles, sniper detection, and machine-assisted sound localization.
Bulletin of Environmental Contamination and Toxicology, 1990
Throughput of input queued switches is limited to 58.6% due to head of line blocking (HoL). Using... more Throughput of input queued switches is limited to 58.6% due to head of line blocking (HoL). Using virtual output queuing (VOQ) at inputs and a proper scheduling algorithm, near 100% throughput can be achieved. Scaling in terms of number of ports and line rate is an important factor for high-speed switches. Current available switches support line rates about 10 Gbps, which is due to their slow schedulers. A novel schedule called DHL, which is at least 2 times faster than schedulers like iSLIP, is proposed. The scheduler can be used to build very high capacity switches and support data rate up to 20 Gbps while performing better for bursty and IP traffic. The scheduler's speed can be increased 2 times by pipelining. A synthesis of the scheduler is given and its area and delay for different number of switch sizes are provided. DHL scales well in terms of performance, area and delay. Its area and delay scale linear and logarithmic with the number of input ports, respectively, while its performance remains quite the same. The scheduler can be implemented with low complexity for many service policies. Simulation results regarding the average delay, throughput, burst reduction and fairness with respect to the switch size are reported.
Solar Energy Materials and Solar Cells, 1997
... Amira El-Azhary Sonbol ... her husband, and in which the institution of marriage was looser, ... more ... Amira El-Azhary Sonbol ... her husband, and in which the institution of marriage was looser, withdivorce much more accessible to both women and men ... This paper will substantiate these three core propositions by examining the evolution of family laws from the Shari'ah courts in ...
This paper describes the design of the dual band microstrip antenna using scaling factor techniqu... more This paper describes the design of the dual band microstrip antenna using scaling factor technique and inset feed. Square and circular shaped patches have been used to investigate any improvements that can be achieved. The antennas were designed to operate in the ISM band at 2.4 GHz and lower UNII band at 5.2 GHz. The dimensions of each single element
Biodegradation, 2011
The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to ... more The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized in an agricultural soil in France that had been periodically exposed to IPU. Enrichment cultures from samples of this soil isolated a bacterial strain able to mineralize IPU. 16S rRNA sequence analysis showed that this strain belonged to the phylogeny of the genus Sphingomonas (96% similarity with Sphingomonas sp. JEM-14, AB219361) and was designated Sphingomonas sp. strain SH. From this strain, a partial sequence of a 1,2-dioxygenase (catA) gene coding for an enzyme degrading catechol putatively formed during IPU mineralization was amplified. Phylogenetic analysis revealed that the catA sequence was related to Sphingomonas spp. and showed a lack of congruence between the catA and 16S rRNA based phylogenies, implying horizontal gene transfer of the catA gene cluster between soil microbiota. The IPU degrading ability of strain SH was strongly influenced by pH with maximum degradation taking place at pH 7.5. SH was only able to mineralize IPU and its known metabolites including 4-isopropylaniline and it could not degrade other structurally related phenylurea herbicides such as diuron, linuron, monolinuron and chlorotoluron or their aniline derivatives. These observations suggest that the catabolic abilities of the strain SH are highly specific to the metabolism of IPU.
Superallowed 0^+→ 0^+ nuclear beta decays provide the best test of the Conserved Vector Current (... more Superallowed 0^+→ 0^+ nuclear beta decays provide the best test of the Conserved Vector Current (CVC) hypothesis, as well as the most accurate value for the up-down quark-mixing matrix element, V_ud, of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, when combined with the muon lifetime. As part of the on-going effort at Texas A&M University to determine the ft values of Tz = -1 superallowed emitters to within a precision of less than 0.1%, experiments have been conducted to measure the half-lives of ^34Ar (T_1/2 ≈ 0.8 s) and ^34Cl (T_1/2 ≈ 1.53 s) using a 4π proportional gas counter. While ^34Cl is a Tz = 1 superallowed emitter whose ft values have previously been determined to within the required precision, it is also the daughter of ^34Ar. Any measurement of β-particles alone includes the growth and decay of ^34Cl along with the decay of ^34Ar. For this reason, a precise measurement of the ^34Cl half-life has been made in order to improve the precision to which the ^34Ar half-life can be determined. Preliminary results will be outlined and discussed.
Physical Review Letters, 2003
The half-life, 3.8755(12) s, and superallowed branching ratio, 0.5315(12), for ^{22}Mg beta-decay... more The half-life, 3.8755(12) s, and superallowed branching ratio, 0.5315(12), for ^{22}Mg beta-decay have been measured with high precision. The latter depended on gamma-ray intensities being measured with an HPGe detector calibrated for relative efficiencies to an unprecedented 0.15%. Previous precise measurements of 0^+ to 0^+ transitions have been restricted to the nine that populate stable daughter nuclei. No more such cases exist, and any improvement in a critical CKM unitarity test must depend on precise measurements of more exotic nuclei. With this branching-ratio measurement, we show those to be possible for T_z = -1 parents. We obtain a corrected Ft-value of 3071(9) s, in good agreement with expectations.
International Journal of Sustainable Energy, 2011
Jatropha curcas alkyl ester can be produced via a transesterification reaction of J. curcas trigl... more Jatropha curcas alkyl ester can be produced via a transesterification reaction of J. curcas triglyceride (JCT) using an alkaline catalyst with an alcohol. In this study, the reaction was carried out in a batch reactor under various operating conditions. The kinetics study of the transesterification of JCT with methanol was conducted at various temperatures ranging from 50 °C to 65 °C. The conversion of triglyceride (TG) and diglyceride (DG) into biodiesel followed a first-order mechanism, while the conversion of monoglyceride into biodiesel occurred too fast, thus assuming a non-limiting step. The reaction rate constants were determined and then plotted against temperatures for the determination of activation energies. The values of k TG ranged from 0.11 to 0.17 min−1 and the values of k DG ranged from 0.07 to 0.20 min−1. The activation energies for the transesterification of TG/DG with methanol were 27.38 and 46.72 kJ mol−1, respectively. The high E a values indicate that the transesterification of J. curcas is sensitive to temperature changes.
Applied Mathematical Modelling, 2009
A solution for the elastic and inelastic local buckling of flat rectangular plates with centerlin... more A solution for the elastic and inelastic local buckling of flat rectangular plates with centerline boundary conditions subjected to non-uniform in-plane compression and shear stress is presented. The loaded edges are simply supported, the longitudinal edges may have any boundary conditions and the centerline is simply supported with a variable rotational stiffness. The Galerkin method, an effective method for solving differential equations, is applied to establish an eigenvalue problem. In order to obtain plate buckling coefficients, combined trigonometric and polynomial functions that satisfy the boundary conditions are used. The method is programmed, and several numerical examples including elastic and inelastic local buckling, are presented to illustrate the scope and efficacy of the procedure. The variation of buckling coefficients with aspect ratio is presented for various stress gradient ratios. The solution is applicable to stiffened plates and the flange of the I-shaped beams that are subjected to biaxial bending or combined flexure and torsion and shear stresses, and is important to estimate the reduction in elastic buckling capacity due to stress gradient.
Abstract The objective of this paper is to provide technical background and illustrative examples... more Abstract The objective of this paper is to provide technical background and illustrative examples for stability analysis of cold-formed steel members using the conventional and constrained finite strip methods as implemented in the open source program CUFSM. ...
A computer-based algorithm that localizes sounds in near-real time has been developed. The algori... more A computer-based algorithm that localizes sounds in near-real time has been developed. The algorithm takes input from two microphones and estimates the position of the sound source relative to the microphone array. The algorithm requires no a priori knowledge of the stimuli to be localized. The accuracy of the algorithm was tested using binaural recordings from a pair of microphones mounted in the ear canals of an acoustic mannequin. Sounds were played at 5 degree steps around the mannequin and the outputs were recorded at the entrance to each ear canal. These recordings were fed into the algorithm that estimated the location of the incoming sound on the horizontal plane. The algorithm utilizes a Head-Related Transfer Function (HRTF) to estimate the location of incoming sound stimuli. Although the HRTF of the acoustic mannequin was used, any HRTF can be inserted into the algorithm, allowing for predictions about individual performance differences. The results of this effort have been highly encouraging: the algorithm was able to identify accurately the location of a variety of sounds, committing an average of 2.9 degrees of unsigned localization error. Better than chance performance was found in noisy conditions of up to a -10 dB signal-tonoise ratio. The initial purpose of this algorithm is to predict the localization performance afforded by different types of combat helmets. Current and future encapsulating helmet designs are likely to impede localization performance, and an accurate localization model would be an invaluable tool in the helmet selection process. Adapting the model for use as a highly accurate machine-based localizer is an additional goal of this line of research. Applications for this technology include target tracking on unmanned vehicles, sniper detection, and machine-assisted sound localization.
Bulletin of Environmental Contamination and Toxicology, 1990
Throughput of input queued switches is limited to 58.6% due to head of line blocking (HoL). Using... more Throughput of input queued switches is limited to 58.6% due to head of line blocking (HoL). Using virtual output queuing (VOQ) at inputs and a proper scheduling algorithm, near 100% throughput can be achieved. Scaling in terms of number of ports and line rate is an important factor for high-speed switches. Current available switches support line rates about 10 Gbps, which is due to their slow schedulers. A novel schedule called DHL, which is at least 2 times faster than schedulers like iSLIP, is proposed. The scheduler can be used to build very high capacity switches and support data rate up to 20 Gbps while performing better for bursty and IP traffic. The scheduler's speed can be increased 2 times by pipelining. A synthesis of the scheduler is given and its area and delay for different number of switch sizes are provided. DHL scales well in terms of performance, area and delay. Its area and delay scale linear and logarithmic with the number of input ports, respectively, while its performance remains quite the same. The scheduler can be implemented with low complexity for many service policies. Simulation results regarding the average delay, throughput, burst reduction and fairness with respect to the switch size are reported.
Solar Energy Materials and Solar Cells, 1997
... Amira El-Azhary Sonbol ... her husband, and in which the institution of marriage was looser, ... more ... Amira El-Azhary Sonbol ... her husband, and in which the institution of marriage was looser, withdivorce much more accessible to both women and men ... This paper will substantiate these three core propositions by examining the evolution of family laws from the Shari'ah courts in ...
This paper describes the design of the dual band microstrip antenna using scaling factor techniqu... more This paper describes the design of the dual band microstrip antenna using scaling factor technique and inset feed. Square and circular shaped patches have been used to investigate any improvements that can be achieved. The antennas were designed to operate in the ISM band at 2.4 GHz and lower UNII band at 5.2 GHz. The dimensions of each single element
Biodegradation, 2011
The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to ... more The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized in an agricultural soil in France that had been periodically exposed to IPU. Enrichment cultures from samples of this soil isolated a bacterial strain able to mineralize IPU. 16S rRNA sequence analysis showed that this strain belonged to the phylogeny of the genus Sphingomonas (96% similarity with Sphingomonas sp. JEM-14, AB219361) and was designated Sphingomonas sp. strain SH. From this strain, a partial sequence of a 1,2-dioxygenase (catA) gene coding for an enzyme degrading catechol putatively formed during IPU mineralization was amplified. Phylogenetic analysis revealed that the catA sequence was related to Sphingomonas spp. and showed a lack of congruence between the catA and 16S rRNA based phylogenies, implying horizontal gene transfer of the catA gene cluster between soil microbiota. The IPU degrading ability of strain SH was strongly influenced by pH with maximum degradation taking place at pH 7.5. SH was only able to mineralize IPU and its known metabolites including 4-isopropylaniline and it could not degrade other structurally related phenylurea herbicides such as diuron, linuron, monolinuron and chlorotoluron or their aniline derivatives. These observations suggest that the catabolic abilities of the strain SH are highly specific to the metabolism of IPU.
Superallowed 0^+→ 0^+ nuclear beta decays provide the best test of the Conserved Vector Current (... more Superallowed 0^+→ 0^+ nuclear beta decays provide the best test of the Conserved Vector Current (CVC) hypothesis, as well as the most accurate value for the up-down quark-mixing matrix element, V_ud, of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, when combined with the muon lifetime. As part of the on-going effort at Texas A&M University to determine the ft values of Tz = -1 superallowed emitters to within a precision of less than 0.1%, experiments have been conducted to measure the half-lives of ^34Ar (T_1/2 ≈ 0.8 s) and ^34Cl (T_1/2 ≈ 1.53 s) using a 4π proportional gas counter. While ^34Cl is a Tz = 1 superallowed emitter whose ft values have previously been determined to within the required precision, it is also the daughter of ^34Ar. Any measurement of β-particles alone includes the growth and decay of ^34Cl along with the decay of ^34Ar. For this reason, a precise measurement of the ^34Cl half-life has been made in order to improve the precision to which the ^34Ar half-life can be determined. Preliminary results will be outlined and discussed.
Physical Review Letters, 2003
The half-life, 3.8755(12) s, and superallowed branching ratio, 0.5315(12), for ^{22}Mg beta-decay... more The half-life, 3.8755(12) s, and superallowed branching ratio, 0.5315(12), for ^{22}Mg beta-decay have been measured with high precision. The latter depended on gamma-ray intensities being measured with an HPGe detector calibrated for relative efficiencies to an unprecedented 0.15%. Previous precise measurements of 0^+ to 0^+ transitions have been restricted to the nine that populate stable daughter nuclei. No more such cases exist, and any improvement in a critical CKM unitarity test must depend on precise measurements of more exotic nuclei. With this branching-ratio measurement, we show those to be possible for T_z = -1 parents. We obtain a corrected Ft-value of 3071(9) s, in good agreement with expectations.