Journal of Soil Science and Environmental Management, May 31, 2011
Barapukuria is the only natural coalmine reserve in Bangladesh that is in operation. In this stud... more Barapukuria is the only natural coalmine reserve in Bangladesh that is in operation. In this study, an attempt was taken to conduct environmental impact assessment of Barapukuria thermal power and coal mining project through environmental, socio-economical and meteorological study. The analysis showed that, the Mn concentration was found in the satisfactory range. The pH was found slightly alkaline and surface water was bacteria contaminated. SO 4 2concentration was in the range of WHO standard. Calculated SO x loading was almost same of monitored emission. Corresponding estimated concentration of SO x was in acceptable range, which may not bring any matter of concern. In the study, an attempt was also made to evaluate the health impacts of SPM (suspended particulate matter) emitted from the combustion of coal in the power plant. The socio economic condition was also considered a dominating factor, for the EIA along with the chemical parameters since increased employment for the project. In general, this study includes comprehensive baseline data for decision makers to evaluate the feasibility of coal power industry at Barapukuria and the coalmine itself.
Oral health in cancer patients was known to influence the quality of life. However, the knowledge... more Oral health in cancer patients was known to influence the quality of life. However, the knowledge of possible factors associated with oral health in cancer patients is seriously lacking in Saudi Arabia. In this study, we aimed to determine the burden of adverse oral health in cancer patients and identify the associated factors for oral health problems. A cross-sectional study design was used to recruit a total of 375 cancer patients who attended oncology outpatient clinics at King Abdulaziz Medical City - Riyadh (KAMC-R) by using a consecutive sampling technique. A self-reporting questionnaire was used to collect the sociodemographic information, clinical symptoms, and lifestyle factors of cancer patients. Furthermore, depression, anxiety, and stress were assessed by using Depression Anxiety and Stress Scale. The authors assessed the oral health complaints based on seven common conditions (bleeding gums, toothache, mouth ulcers, bruxism, xerostomia, problems affecting speech, and sa...
Although psychological symptoms and oral health status are associated with health management and ... more Although psychological symptoms and oral health status are associated with health management and outcomes among cancer patients, their association has not been assessed in Saudi Arabia. We aimed to assess the symptoms of depression, anxiety, and stress and their association with their oral health status, adjusting for sociodemographic and clinical factors. A self-reported study included 375 adult cancer patients who received outpatient healthcare services in the Oncology Department, King Abdulaziz Medical City-Riyadh, Saudi Arabia, between April 1 and August 31, 2017. We used the Arabic version of the Depression Anxiety Stress Scale to dichotomize a binary outcome for each. Oral health was evaluated by self-rating from "very good" to "bad". A high prevalence of subjective depression, anxiety, and stress was found (44.8%, 52.5%, and 42.7%, respectively). Of the sample, 17.9% self-reported "bad" oral health, which is associated with a high risk of anxiety...
Dengue and chikungunya fevers are transmitted by the common mosquito vector Aedes and malaria by ... more Dengue and chikungunya fevers are transmitted by the common mosquito vector Aedes and malaria by Anopheles. Concurrent infections are reported due to co-circulation of these pathogens, especially in endemic regions. We report a rare case of triple infection with 3 arthropod-borne pathogens (Plasmodium vivax and the dengue and chikungunya viruses) in a 3-year-old child from New Delhi, India, in August 2016. The viruses were identified by RT-PCR and the parasite by microscopy and antigen detection. The dengue virus serotype 3 sequence was clustered in the genotype III by the phylogenetic analysis. Mixed infection with multiple pathogens is a challenge for accurate diagnosis due to the overlapping clinical symptoms. The accurate and timely diagnosis of multiple pathogens in such cases is important for rapid and effective patient management.
Background/propose. Sleep disturbance and excessive daytime sleepiness (EDS) have been reported i... more Background/propose. Sleep disturbance and excessive daytime sleepiness (EDS) have been reported in patients with hepatic cirrhosis with no hepatic encephalopathy (HE). The objective of this study was to evaluate daytime sleepiness and risk of obstructive sleep apnea (OSA) among liver cirrhosis patients. A cross-sectional study was conducted at King Abdulaziz Medical City (KAMC)-Riyadh over a period of six months, using a structured questionnaire that investigated: 1) Sleep patterns and daytime sleepiness using the Epworth Sleeping Scale (ESS), and 2) The risk for sleep apnea using the Berlin Questionnaire (BQ). We enrolled patients with a confirmed diagnosis of liver cirrhosis who were being followed at the hepatology and pre-liver transplant clinics. We enrolled 200 patients with liver cirrhosis, 57.5% of whom were male. The mean age was 60 (± SD 12.2). The reported prevalence of EDS, OSA, and both EDS and OSA were 29.5%, 42.9%, and 13.6%, respectively. The prevalence of EDS was hi...
Jahdali (2015) Effect of age and gender in the prevalence of excessive daytime sleepiness among a... more Jahdali (2015) Effect of age and gender in the prevalence of excessive daytime sleepiness among a sample of the Saudi population,
A rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a corresponding Reynolds num... more A rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a corresponding Reynolds number of 7.35 × 10 6 /m. High speed shadowgraph movies were simultaneously sampled with dynamic pressure sensors at 75 kHz. Fourier analysis was performed on the high speed movies as well as the dynamic pressure data, which resulted in the determination of spatial and temporal characteristics of the dominant cavity frequencies in the flow field. Four passive flow control devices were tested, two of which have historically performed well at reducing the acoustic tones and broadband noise levels. The other two devices were less effective. Flow physics based on the detailed analysis of the high speed shadowgraphs and dynamic pressures sensors is presented.
Preliminary results are presented for Steady-state Reynolds-Averaged Navier-Stokes (RANS) simulat... more Preliminary results are presented for Steady-state Reynolds-Averaged Navier-Stokes (RANS) simulations of the flow in the empty wind tunnel. Also presented are the experimental results of flow visualization over the simplified tractor/trailer geometry conducted at Auburn University. The simulations of the empty wind tunnel are carried out to determine the position of the simplified tractor/trailer geometry in the test section of the wind tunnel relative to the test section floor. It is observed from the computational simulations that the boundary layer thickness on the test section floor at the beginning of the test section is 0.3 inches and at the position where the trailer ends is 0.9 inches. The computational results of the empty wind tunnel are compared with the experimental data for validation. The comparisons include the boundary layer properties on the test section floor and the flow angularity calculations at the beginning of the test section. Some preliminary experiments were conducted on the simplified tractor/trailer geometry placed in the wind tunnel. A symmetric flow pattern moving outward from the center of the model is observed on the front side of the tractor. As the flow accelerated past the corner, it is observed that the flow undergoes laminar separation followed by a turbulent reattachment. Flow on the top of the tractor and also the trailer was observed to be smooth.
Background Sleep disturbances are common and were recognized as one of early features of cirrhoti... more Background Sleep disturbances are common and were recognized as one of early features of cirrhotic patients with hepatic encephalopathy (1-3). Although early studies revealed that inverse sleep pattern is an early sign of hepatic encephalopathy, Montagnese and colleagues did not find any correlation between the circadian rhythm abnormalities and hepatic encephalopathy (4). Few studies are available regarding the prevalence of sleep disturbance in cirrhotic patients without overt hepatic encephalopathy (1, 2, 5, 6). These studies on the prevalence of sleep disturbance revealed wide variations ranging from 27-70 per cent (1, 2, 4-6). The most common sleep disorders reported in patients with liver cirrhosis are poor sleep quality, frequent awakening, difficulty falling asleep after awakening, prolonged sleeping latency, delayed bedtime, delayed wake-up time, excessive daytime sleepiness and preference for evening activities (1-4, 6-14). Unfortunately, sleep disorders among liver cirrhosis patients are not only under-diagnosed and poorly managed, but they are also associated with poor survival rates (5, 8, 15). The exact mechanism of sleep disturbance in liver cirrhosis is still a controversial issue in the literature. Many hypotheses have been proposed to explain the origin of sleep disturbance in liver cirrhosis patients without encephalopathy but none of them has completely demonstrated a strong association. In liver cirrhosis patients, the diurnal plasma melatonin profile showed a significant delay in the onset of plasma melatonin release and in its nocturnal peak level (14-18). Furthermore, studies have shown improvement of melatonin and circadian rhythm post liver transplants (18). This disturbance of the melatonin profile may reflect the changes in the circadian rhythm. However, Rodrigue and colleagues reported sleep disturbance in approximately 55 per cent of pre-transplant
Topological features of the flow emanating from a radial jet nozzle and its subsequent reattachme... more Topological features of the flow emanating from a radial jet nozzle and its subsequent reattachment on a fiat surface were investigated using a variety of flow visualization techniques in the Texas A & M University (TAMU) water tunnel. Dominant features of the flow were observed to be the bifurcation of streamsurface after a turbulent reattachment into inner and outer flows. The inner flow was dominated by a sequence of events consisting of the recirculation, formation and breakup of the ring vortex into foci structures, mass entrainment and ejection. Outer flow exhibited formation of secondary vortices, and shear layer instabilities.
The combination of sulfadoxine-pyrimethamine (SP) is used as a second line of therapy for the tre... more The combination of sulfadoxine-pyrimethamine (SP) is used as a second line of therapy for the treatment of uncomplicated chloroquine-resistant Plasmodium falciparum malaria. Resistance to SP arises due to certain point mutations in the genes for the dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) enzymes of the parasite. We have analyzed these mutations in 312 field isolates of P. falciparum collected from different parts of India to assess the effects of drug pressure. The rate of mutation in the gene for DHFR was found to be higher than that in the gene for DHPS, although the latter had mutations in more alleles. There was a temporal rise in the number of isolates with double dhfr mutations and single dhps mutations, resulting in an increased total number of mutations in the loci for DHFR and DHPS combined over a 5-year period. During these 5 years, the number of isolates with drug-sensitive genotypes decreased and the number of isolates with drug-resistant ge...
Parabolized and iterative Navier-Stokes codes are used to predict flowfield solutions around a hy... more Parabolized and iterative Navier-Stokes codes are used to predict flowfield solutions around a hypersonic vehicle. Aerodynamic force and moment predictions from the codes are compared with experimental data from the Sandia National Laboratories Mach 8 wind tunnel. The comparisons are made on a spherically blunted cone with a slice parallel to the body axis. On the slice portion of the vehicle, a flap can be attached so that deflection angles of 10, 20, and 30 deg can be obtained. The Sandia parabolized Navier-Stokes code is used to generate solutions for the sliced vehicle with no flap. For the vehicle with a flap, axially separated flow occurs, and a time iterative Navier-Stokes code is used to provide comparisons with the data. Aerodynamic force and moment comparisons are made for laminar flow, and an ideal gas is assumed in the calculations. A detailed study of grid convergence is presented to determine the accuracy of the numerical solutions. Predictions obtained from the codes show very good agreement with the experimental data for force and moment coefficients, except for large flap deflections.
46th AIAA Aerospace Sciences Meeting and Exhibit, 2008
Reported are the results of experiments conducted on a slender delta wing designed to undergo rol... more Reported are the results of experiments conducted on a slender delta wing designed to undergo roll and yaw oscillations simultaneously. Wind tunnel and water tunnel results indicate that the yaw oscillations always preceded roll oscillations. Time histories show coupling between roll and yaw motions. A significant drop in lift coefficient was observed during these motions. There exists a bifurcation angle of attack at which coupled yaw and roll oscillations force the moment coefficients to switch sign. Pertinent results of the ongoing research work are presented.
Dengue fever is the most prevalent arboviral disease in the tropical and sub-tropical regions of ... more Dengue fever is the most prevalent arboviral disease in the tropical and sub-tropical regions of the world. The present report describes molecular detection and serotyping of dengue viruses in acute phase blood samples collected from New Delhi, India. Phylogenetic and molecular clock analysis of dengue virus serotype 1 and 3 strains were also investigated. Dengue virus infection was detected in 68.87% out of 604 samples tested by RT-PCR between 2011 & 2014. Dengue serotype 1 was detected in 25.48% samples, dengue serotype 2 in 79.56% samples and dengue serotype 3 in 11.29% samples. Dengue serotype 4 was not detected. Co-infection by more than one dengue serotype was detected in 18.26% samples. Envelope gene of 29 DENV-1 and 14 DENV-3 strains were sequenced in the study. All the DENV-1 strains grouped with the American African genotype. All DENV-3 strains were found to belong to Genotype III. Nucleotide substitution rates of dengue 1 and 3 viruses were determined in the study. Time to the most recent common ancestor (TMRCA) of dengue 1 viruses was determined to be 132 years. TMRCA of DENV-3 viruses was estimated to be 149 years. Bayesian skyline plots were constructed for Indian DENV-1 and 3 strains which showed a decrease in population size since 2005 in case of DENV-1 strains while no change was observed in recent years in case of DENV-3 strains. The study also revealed a change in the dominating serotype in Delhi, India in recent years. The study will be helpful in formulating control strategies for the outbreaks. In addition, it will also assist in tracking the movement and evolution of this emerging virus.
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012
An experimental investigation was conducted on the flow fields behind various hemisphereon-cylind... more An experimental investigation was conducted on the flow fields behind various hemisphereon-cylinder turret geometries in subsonic flow. The effects that geometric modifications had on the baseline flow field were characterized to determine which designs, if any, demonstrate potential as passive flow control mechanisms. Qualitative results were obtained for each turret model using a pulse burst laser to perform three-dimensional flow visualization. Additional, quantitative measurements along the wake centerline for each design were made via planar particle image velocimetry (PIV). The results of each modified flow field are presented with the baseline case for comparison. Suggested future work is also given for those designs showing the most promise as passive flow control devices.
An examination of a rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a correspo... more An examination of a rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a corresponding Reynolds number of 2.3x10 6 /ft. High speed shadowgraph movies were simultaneously sampled with dynamic pressure sensors at 75 kHz. Fourier analysis was performed on the high speed movies as well as the dynamic pressure data, which resulted in determining the locations of dominant cavity frequencies in the flow field. Four passive flow control devices were tested, two of which have historically preformed well, while two neither reduced the main acoustic tones nor reduced the broadband levels. From the high speed shadowgraph movies, observations are made in the changes in the cavity flow physics when the passive flow control devices are used, and will be discussed.
Journal of Soil Science and Environmental Management, May 31, 2011
Barapukuria is the only natural coalmine reserve in Bangladesh that is in operation. In this stud... more Barapukuria is the only natural coalmine reserve in Bangladesh that is in operation. In this study, an attempt was taken to conduct environmental impact assessment of Barapukuria thermal power and coal mining project through environmental, socio-economical and meteorological study. The analysis showed that, the Mn concentration was found in the satisfactory range. The pH was found slightly alkaline and surface water was bacteria contaminated. SO 4 2concentration was in the range of WHO standard. Calculated SO x loading was almost same of monitored emission. Corresponding estimated concentration of SO x was in acceptable range, which may not bring any matter of concern. In the study, an attempt was also made to evaluate the health impacts of SPM (suspended particulate matter) emitted from the combustion of coal in the power plant. The socio economic condition was also considered a dominating factor, for the EIA along with the chemical parameters since increased employment for the project. In general, this study includes comprehensive baseline data for decision makers to evaluate the feasibility of coal power industry at Barapukuria and the coalmine itself.
Oral health in cancer patients was known to influence the quality of life. However, the knowledge... more Oral health in cancer patients was known to influence the quality of life. However, the knowledge of possible factors associated with oral health in cancer patients is seriously lacking in Saudi Arabia. In this study, we aimed to determine the burden of adverse oral health in cancer patients and identify the associated factors for oral health problems. A cross-sectional study design was used to recruit a total of 375 cancer patients who attended oncology outpatient clinics at King Abdulaziz Medical City - Riyadh (KAMC-R) by using a consecutive sampling technique. A self-reporting questionnaire was used to collect the sociodemographic information, clinical symptoms, and lifestyle factors of cancer patients. Furthermore, depression, anxiety, and stress were assessed by using Depression Anxiety and Stress Scale. The authors assessed the oral health complaints based on seven common conditions (bleeding gums, toothache, mouth ulcers, bruxism, xerostomia, problems affecting speech, and sa...
Although psychological symptoms and oral health status are associated with health management and ... more Although psychological symptoms and oral health status are associated with health management and outcomes among cancer patients, their association has not been assessed in Saudi Arabia. We aimed to assess the symptoms of depression, anxiety, and stress and their association with their oral health status, adjusting for sociodemographic and clinical factors. A self-reported study included 375 adult cancer patients who received outpatient healthcare services in the Oncology Department, King Abdulaziz Medical City-Riyadh, Saudi Arabia, between April 1 and August 31, 2017. We used the Arabic version of the Depression Anxiety Stress Scale to dichotomize a binary outcome for each. Oral health was evaluated by self-rating from "very good" to "bad". A high prevalence of subjective depression, anxiety, and stress was found (44.8%, 52.5%, and 42.7%, respectively). Of the sample, 17.9% self-reported "bad" oral health, which is associated with a high risk of anxiety...
Dengue and chikungunya fevers are transmitted by the common mosquito vector Aedes and malaria by ... more Dengue and chikungunya fevers are transmitted by the common mosquito vector Aedes and malaria by Anopheles. Concurrent infections are reported due to co-circulation of these pathogens, especially in endemic regions. We report a rare case of triple infection with 3 arthropod-borne pathogens (Plasmodium vivax and the dengue and chikungunya viruses) in a 3-year-old child from New Delhi, India, in August 2016. The viruses were identified by RT-PCR and the parasite by microscopy and antigen detection. The dengue virus serotype 3 sequence was clustered in the genotype III by the phylogenetic analysis. Mixed infection with multiple pathogens is a challenge for accurate diagnosis due to the overlapping clinical symptoms. The accurate and timely diagnosis of multiple pathogens in such cases is important for rapid and effective patient management.
Background/propose. Sleep disturbance and excessive daytime sleepiness (EDS) have been reported i... more Background/propose. Sleep disturbance and excessive daytime sleepiness (EDS) have been reported in patients with hepatic cirrhosis with no hepatic encephalopathy (HE). The objective of this study was to evaluate daytime sleepiness and risk of obstructive sleep apnea (OSA) among liver cirrhosis patients. A cross-sectional study was conducted at King Abdulaziz Medical City (KAMC)-Riyadh over a period of six months, using a structured questionnaire that investigated: 1) Sleep patterns and daytime sleepiness using the Epworth Sleeping Scale (ESS), and 2) The risk for sleep apnea using the Berlin Questionnaire (BQ). We enrolled patients with a confirmed diagnosis of liver cirrhosis who were being followed at the hepatology and pre-liver transplant clinics. We enrolled 200 patients with liver cirrhosis, 57.5% of whom were male. The mean age was 60 (± SD 12.2). The reported prevalence of EDS, OSA, and both EDS and OSA were 29.5%, 42.9%, and 13.6%, respectively. The prevalence of EDS was hi...
Jahdali (2015) Effect of age and gender in the prevalence of excessive daytime sleepiness among a... more Jahdali (2015) Effect of age and gender in the prevalence of excessive daytime sleepiness among a sample of the Saudi population,
A rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a corresponding Reynolds num... more A rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a corresponding Reynolds number of 7.35 × 10 6 /m. High speed shadowgraph movies were simultaneously sampled with dynamic pressure sensors at 75 kHz. Fourier analysis was performed on the high speed movies as well as the dynamic pressure data, which resulted in the determination of spatial and temporal characteristics of the dominant cavity frequencies in the flow field. Four passive flow control devices were tested, two of which have historically performed well at reducing the acoustic tones and broadband noise levels. The other two devices were less effective. Flow physics based on the detailed analysis of the high speed shadowgraphs and dynamic pressures sensors is presented.
Preliminary results are presented for Steady-state Reynolds-Averaged Navier-Stokes (RANS) simulat... more Preliminary results are presented for Steady-state Reynolds-Averaged Navier-Stokes (RANS) simulations of the flow in the empty wind tunnel. Also presented are the experimental results of flow visualization over the simplified tractor/trailer geometry conducted at Auburn University. The simulations of the empty wind tunnel are carried out to determine the position of the simplified tractor/trailer geometry in the test section of the wind tunnel relative to the test section floor. It is observed from the computational simulations that the boundary layer thickness on the test section floor at the beginning of the test section is 0.3 inches and at the position where the trailer ends is 0.9 inches. The computational results of the empty wind tunnel are compared with the experimental data for validation. The comparisons include the boundary layer properties on the test section floor and the flow angularity calculations at the beginning of the test section. Some preliminary experiments were conducted on the simplified tractor/trailer geometry placed in the wind tunnel. A symmetric flow pattern moving outward from the center of the model is observed on the front side of the tractor. As the flow accelerated past the corner, it is observed that the flow undergoes laminar separation followed by a turbulent reattachment. Flow on the top of the tractor and also the trailer was observed to be smooth.
Background Sleep disturbances are common and were recognized as one of early features of cirrhoti... more Background Sleep disturbances are common and were recognized as one of early features of cirrhotic patients with hepatic encephalopathy (1-3). Although early studies revealed that inverse sleep pattern is an early sign of hepatic encephalopathy, Montagnese and colleagues did not find any correlation between the circadian rhythm abnormalities and hepatic encephalopathy (4). Few studies are available regarding the prevalence of sleep disturbance in cirrhotic patients without overt hepatic encephalopathy (1, 2, 5, 6). These studies on the prevalence of sleep disturbance revealed wide variations ranging from 27-70 per cent (1, 2, 4-6). The most common sleep disorders reported in patients with liver cirrhosis are poor sleep quality, frequent awakening, difficulty falling asleep after awakening, prolonged sleeping latency, delayed bedtime, delayed wake-up time, excessive daytime sleepiness and preference for evening activities (1-4, 6-14). Unfortunately, sleep disorders among liver cirrhosis patients are not only under-diagnosed and poorly managed, but they are also associated with poor survival rates (5, 8, 15). The exact mechanism of sleep disturbance in liver cirrhosis is still a controversial issue in the literature. Many hypotheses have been proposed to explain the origin of sleep disturbance in liver cirrhosis patients without encephalopathy but none of them has completely demonstrated a strong association. In liver cirrhosis patients, the diurnal plasma melatonin profile showed a significant delay in the onset of plasma melatonin release and in its nocturnal peak level (14-18). Furthermore, studies have shown improvement of melatonin and circadian rhythm post liver transplants (18). This disturbance of the melatonin profile may reflect the changes in the circadian rhythm. However, Rodrigue and colleagues reported sleep disturbance in approximately 55 per cent of pre-transplant
Topological features of the flow emanating from a radial jet nozzle and its subsequent reattachme... more Topological features of the flow emanating from a radial jet nozzle and its subsequent reattachment on a fiat surface were investigated using a variety of flow visualization techniques in the Texas A & M University (TAMU) water tunnel. Dominant features of the flow were observed to be the bifurcation of streamsurface after a turbulent reattachment into inner and outer flows. The inner flow was dominated by a sequence of events consisting of the recirculation, formation and breakup of the ring vortex into foci structures, mass entrainment and ejection. Outer flow exhibited formation of secondary vortices, and shear layer instabilities.
The combination of sulfadoxine-pyrimethamine (SP) is used as a second line of therapy for the tre... more The combination of sulfadoxine-pyrimethamine (SP) is used as a second line of therapy for the treatment of uncomplicated chloroquine-resistant Plasmodium falciparum malaria. Resistance to SP arises due to certain point mutations in the genes for the dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) enzymes of the parasite. We have analyzed these mutations in 312 field isolates of P. falciparum collected from different parts of India to assess the effects of drug pressure. The rate of mutation in the gene for DHFR was found to be higher than that in the gene for DHPS, although the latter had mutations in more alleles. There was a temporal rise in the number of isolates with double dhfr mutations and single dhps mutations, resulting in an increased total number of mutations in the loci for DHFR and DHPS combined over a 5-year period. During these 5 years, the number of isolates with drug-sensitive genotypes decreased and the number of isolates with drug-resistant ge...
Parabolized and iterative Navier-Stokes codes are used to predict flowfield solutions around a hy... more Parabolized and iterative Navier-Stokes codes are used to predict flowfield solutions around a hypersonic vehicle. Aerodynamic force and moment predictions from the codes are compared with experimental data from the Sandia National Laboratories Mach 8 wind tunnel. The comparisons are made on a spherically blunted cone with a slice parallel to the body axis. On the slice portion of the vehicle, a flap can be attached so that deflection angles of 10, 20, and 30 deg can be obtained. The Sandia parabolized Navier-Stokes code is used to generate solutions for the sliced vehicle with no flap. For the vehicle with a flap, axially separated flow occurs, and a time iterative Navier-Stokes code is used to provide comparisons with the data. Aerodynamic force and moment comparisons are made for laminar flow, and an ideal gas is assumed in the calculations. A detailed study of grid convergence is presented to determine the accuracy of the numerical solutions. Predictions obtained from the codes show very good agreement with the experimental data for force and moment coefficients, except for large flap deflections.
46th AIAA Aerospace Sciences Meeting and Exhibit, 2008
Reported are the results of experiments conducted on a slender delta wing designed to undergo rol... more Reported are the results of experiments conducted on a slender delta wing designed to undergo roll and yaw oscillations simultaneously. Wind tunnel and water tunnel results indicate that the yaw oscillations always preceded roll oscillations. Time histories show coupling between roll and yaw motions. A significant drop in lift coefficient was observed during these motions. There exists a bifurcation angle of attack at which coupled yaw and roll oscillations force the moment coefficients to switch sign. Pertinent results of the ongoing research work are presented.
Dengue fever is the most prevalent arboviral disease in the tropical and sub-tropical regions of ... more Dengue fever is the most prevalent arboviral disease in the tropical and sub-tropical regions of the world. The present report describes molecular detection and serotyping of dengue viruses in acute phase blood samples collected from New Delhi, India. Phylogenetic and molecular clock analysis of dengue virus serotype 1 and 3 strains were also investigated. Dengue virus infection was detected in 68.87% out of 604 samples tested by RT-PCR between 2011 & 2014. Dengue serotype 1 was detected in 25.48% samples, dengue serotype 2 in 79.56% samples and dengue serotype 3 in 11.29% samples. Dengue serotype 4 was not detected. Co-infection by more than one dengue serotype was detected in 18.26% samples. Envelope gene of 29 DENV-1 and 14 DENV-3 strains were sequenced in the study. All the DENV-1 strains grouped with the American African genotype. All DENV-3 strains were found to belong to Genotype III. Nucleotide substitution rates of dengue 1 and 3 viruses were determined in the study. Time to the most recent common ancestor (TMRCA) of dengue 1 viruses was determined to be 132 years. TMRCA of DENV-3 viruses was estimated to be 149 years. Bayesian skyline plots were constructed for Indian DENV-1 and 3 strains which showed a decrease in population size since 2005 in case of DENV-1 strains while no change was observed in recent years in case of DENV-3 strains. The study also revealed a change in the dominating serotype in Delhi, India in recent years. The study will be helpful in formulating control strategies for the outbreaks. In addition, it will also assist in tracking the movement and evolution of this emerging virus.
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012
An experimental investigation was conducted on the flow fields behind various hemisphereon-cylind... more An experimental investigation was conducted on the flow fields behind various hemisphereon-cylinder turret geometries in subsonic flow. The effects that geometric modifications had on the baseline flow field were characterized to determine which designs, if any, demonstrate potential as passive flow control mechanisms. Qualitative results were obtained for each turret model using a pulse burst laser to perform three-dimensional flow visualization. Additional, quantitative measurements along the wake centerline for each design were made via planar particle image velocimetry (PIV). The results of each modified flow field are presented with the baseline case for comparison. Suggested future work is also given for those designs showing the most promise as passive flow control devices.
An examination of a rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a correspo... more An examination of a rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a corresponding Reynolds number of 2.3x10 6 /ft. High speed shadowgraph movies were simultaneously sampled with dynamic pressure sensors at 75 kHz. Fourier analysis was performed on the high speed movies as well as the dynamic pressure data, which resulted in determining the locations of dominant cavity frequencies in the flow field. Four passive flow control devices were tested, two of which have historically preformed well, while two neither reduced the main acoustic tones nor reduced the broadband levels. From the high speed shadowgraph movies, observations are made in the changes in the cavity flow physics when the passive flow control devices are used, and will be discussed.
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Papers by Anwar Ahmed