Sharif Digital Repository

Inspired by Williamson’s knowledge-first epistemology, I propose a position on practical knowledge that can be called the ‘know-how-first view’; yet whereas Williamson is one of the pioneers of the new intellectualism about know-how, I employ the know-how-first view to argue against intellectualism and instead develop a know-how-first version of anti-intellectualism. Williamson argues that propositional knowledge is a sui generis unanalyzable mental state that comes first in the epistemic realm; in parallel, I propose that know-how is a sui generis unanalyzable power that comes first in the practical realm. To motivate this suggestion, I put forward two arguments: (1) drawing on... 

The trade-off between the fuel consumption and drag coefficient makes the investigations of drag reduction of utmost importance. In this paper, the rear-end shape optimization of Ahmed body is performed. Before changing the geometry, to identify the suitable simulation method and validate it, the standard Ahmed body is simulated using k − ω shear stress transport (SST) and k-epsilon turbulence models. The slant angle, rear box angle, and rear box length as variables were optimized simultaneously. Optimizations conducted by genetic algorithm (GA) and particle swarm optimization (PSO) methods indicate a 26.3% decrease in the drag coefficient. To ensure the validity of the results, a... 

Dust storms are a common phenomenon in arid and semi-arid regions in West Asia, which has led to high levels of PM10 in local and remote area. The Yazd city in Iran with a high PM10 level located downstream of dust sources in the Middle East and Central Asia. In this study, based on meteorological and PM10 monitoring data, backward trajectory modeling of air parcels related to dust events at Yazd station was performed using the HYSPLIT model in 2012–2019. The trajectory cluster analysis was used to identify the main dust transport pathways and wind systems. Three methods of Cross-referencing Backward Trajectory (CBT), Potential Source Contribution Function (PSCF) and Concentration Weighted... 

Freeze desalination (FD) works upon the separation of impurities from pure water during ice crystals formation. The required cold source could be supplied by the cold energy of liquefied natural gas (LNG). In the current study, freeze desalination of seawater is explored by directly exploiting the cold energy of LNG within an appropriate range of temperature after producing work in a power generation cycle. A detailed discussion has been given on the inlet temperature of LNG to the FD unit for the first time. The direct utilization has the privilege of eliminating the addition of a secondary refrigerant and its refrigeration cycle to the FD process. A multi-objective optimization is... 

Background: Hearing loss affects access to spoken language, which can affect cognition and development, and can negatively affect social wellbeing. We present updated estimates from the Global Burden of Disease (GBD) study on the prevalence of hearing loss in 2019, as well as the condition's associated disability. Methods: We did systematic reviews of population-representative surveys on hearing loss prevalence from 1990 to 2019. We fitted nested meta-regression models for severity-specific prevalence, accounting for hearing aid coverage, cause, and the presence of tinnitus. We also forecasted the prevalence of hearing loss until 2050. Findings: An estimated 1·57 billion (95% uncertainty... 

Purpose: Spiral-wound heat exchangers (SWHEs) are widely used in different industries. In special applications, such as cryogenic (HEs), fluid properties may significantly depend on fluid temperature. This paper aims to present an analytical method for design and rating of SWHEs considering variable fluid properties with consistent shell geometry and single-phase fluid. Design/methodology/approach: To consider variations of fluid properties, the HE is divided into identical segments, and the fluid properties are assumed to be constant in each segment. Validation of the analytical method is accomplished by using three-dimensional numerical simulation with shear stress transport k-ω model, and... 

The trade-off between the fuel consumption and drag coefficient makes the investigations of drag reduction of utmost importance. In this paper, the rear-end shape optimization of Ahmed body is performed. Before changing the geometry, to identify the suitable simulation method and validate it, the standard Ahmed body is simulated using k − ω shear stress transport (SST) and k-epsilon turbulence models. The slant angle, rear box angle, and rear box length as variables were optimized simultaneously. Optimizations conducted by genetic algorithm (GA) and particle swarm optimization (PSO) methods indicate a 26.3% decrease in the drag coefficient. To ensure the validity of the results, a... 

The interaction between polymer and surfactant molecules affects the physical properties of liquids, which could be of great importance in an abundance of processes related to drop formation. Polymer and surfactant concentration is a factor that dramatically impacts the shape of molecular networks formed in the fluid bulk and the characteristics of a forming drop. In this study, the deformation and detachment of aqueous carboxymethyl cellulose (CMC) solutions' drops containing different concentrations of sodium dodecyl sulfate (SDS) are studied experimentally. Our purpose is to determine the effects of CMC and SDS concentrations on the parameters related to the formation process, including... 

The trade-off between the fuel consumption and drag coefficient makes the investigations of drag reduction of utmost importance. In this paper, the rear-end shape optimization of Ahmed body is performed. Before changing the geometry, to identify the suitable simulation method and validate it, the standard Ahmed body is simulated using k − ω shear stress transport (SST) and k-epsilon turbulence models. The slant angle, rear box angle, and rear box length as variables were optimized simultaneously. Optimizations conducted by genetic algorithm (GA) and particle swarm optimization (PSO) methods indicate a 26.3% decrease in the drag coefficient. To ensure the validity of the results, a... 

Among the parameters affecting the critical velocity in tunnel fires, the tunnel cross-sectional shape could significantly affect the tunnel fire characteristics, mainly due to the wall-bounded physics of the tunnel fire. Previously, the effects of the cross-sectional geometry of the tunnel were calculated using the non-dimensional analysis and hydraulic height of the tunnel. The dimensionless analysis using hydraulic height calculates only the effects of the tunnel sizes and does not capture the effects of the shape of the tunnel cross-section. Developing a 3D computational fluid dynamics tool using the body-fitted grids, the critical velocities are calculated for the 7 different... 

In this study, the dynamics of the accelerated and steady-state motion of a single bubble in a quiescent highly viscous Newtonian liquid was investigated theoretically and experimentally. The presented mathematical model was based on Newton's second law of motion and a balance of buoyancy, drag, history, and added-mass forces. Due to the presence of non-linear terms in the equation of motion, homotopy perturbation method was used as a powerful analytical method to calculate the velocity analytically. To obtain accurate results in the experiments, a high-speed camera was used to record the bubble motion from the moment of detachment to the time at which the terminal velocity is reached.... 

Purpose: Spiral-wound heat exchangers (SWHEs) are widely used in different industries. In special applications, such as cryogenic (HEs), fluid properties may significantly depend on fluid temperature. This paper aims to present an analytical method for design and rating of SWHEs considering variable fluid properties with consistent shell geometry and single-phase fluid. Design/methodology/approach: To consider variations of fluid properties, the HE is divided into identical segments, and the fluid properties are assumed to be constant in each segment. Validation of the analytical method is accomplished by using three-dimensional numerical simulation with shear stress transport k-ω model, and... 

Background: Accurate and up-to-date assessment of demographic metrics is crucial for understanding a wide range of social, economic, and public health issues that affect populations worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 produced updated and comprehensive demographic assessments of the key indicators of fertility, mortality, migration, and population for 204 countries and territories and selected subnational locations from 1950 to 2019. Methods: 8078 country-years of vital registration and sample registration data, 938 surveys, 349 censuses, and 238 other sources were identified and used to estimate age-specific fertility. Spatiotemporal... 

Background: In an era of shifting global agendas and expanded emphasis on non-communicable diseases and injuries along with communicable diseases, sound evidence on trends by cause at the national level is essential. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) provides a systematic scientific assessment of published, publicly available, and contributed data on incidence, prevalence, and mortality for a mutually exclusive and collectively exhaustive list of diseases and injuries. Methods: GBD estimates incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) due to 369 diseases and... 

Background: Rigorous analysis of levels and trends in exposure to leading risk factors and quantification of their effect on human health are important to identify where public health is making progress and in which cases current efforts are inadequate. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 provides a standardised and comprehensive assessment of the magnitude of risk factor exposure, relative risk, and attributable burden of disease. Methods: GBD 2019 estimated attributable mortality, years of life lost (YLLs), years of life lived with disability (YLDs), and disability-adjusted life-years (DALYs) for 87 risk factors and combinations of risk factors, at... 

The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 provides a rules-based synthesis of the available evidence on levels and trends in health outcomes, a diverse set of risk factors, and health system responses. GBD 2019 covered 204 countries and territories, as well as first administrative level disaggregations for 22 countries, from 1990 to 2019. Because GBD is highly standardised and comprehensive, spanning both fatal and non-fatal outcomes, and uses a mutually exclusive and collectively exhaustive list of hierarchical disease and injury causes, the study provides a powerful basis for detailed and broad insights on global health trends and emerging challenges. GBD... 

Reversible axial flow fans, used in tunnel ventilation systems are designed in a way that as the direction of impeller rotation changes, suction and discharge directions change without any sensible change in flow rate and pressure. Also, their reversibility must be higher than 90%. Therefore, the blade profiles of these fans (S-shaped or elliptic) are designed symmetrically. In the current work, a reversible axial flow fan was studied experimentally and numerically in various ambient conditions and blade positions. Additionally, the experimental test of the fan was performed according to the AMCA-210 standard. Comparison of simulation and experimental results indicated the acceptable... 

In the present study, the formation of surfactant-laden viscous drops in ambient air is experimentally investigated using a high-speed digital camera. The mixtures of 90%, 92.5%, and 95% glycerol by weight in water containing various concentrations of sodium dodecyl sulfate are chosen as the drop phase fluid. The focus of this work is to investigate the effects of concentration of surfactant dissolved in solutions with different viscosities, on physical and geometrical parameters related to drop formation process, such as the drop elongation, minimum neck thickness, formation time, and the drop volume. The formation of satellite drops and the influence of surfactant concentration on their... 

Access to potable water with standard quality is an inevitable component of human's lives. Freeze desalination, by consuming lower energy compared to other techniques, relies on the exertion of a cold source which is then accompanied by simultaneous rejection of impurities from water. Regarding this, a numerical study on freeze desalination in a hollow cylinder is carried out to determine the effects of the design variables such as heat flux, hydraulic diameter, initial salt concentration, and freezing time on the ice mass, ice salinity, ice generation speed, and Nusselt number on the cold surface of the inner tube. Results show that increasing the value of heat flux from −250 [Formula... 

Optimized and informed design of impinging jets can effectively enhance their rate of heat transfer. One practical pathway for such designing is to add nanoparticles to a background fluid. Here, we determine the effects of nanoparticle chemistry, their size, and their total volume fraction in water on the rate of heat transfer. We perform a comprehensive optimization using artificial neural network (ANN) and genetic algorithm (GA) to systematically study the enhanced heat transfer in nanofluids compared to pure water in obtaining a uniform cooling on a constantly heated surface in a turbulent flow. Our results indicate that increasing the size and concentration of nanoparticles enhances the...