Nonlinear fraction-order finite-speed refined Lord–Shulman (LS) thermoelastic wave propagation, reflection, and mixing analyses are accomplished here for rotating annular discs that may be subjected ...to not only thermal but also mechanical boundary conditions. It is the first time that the initial pre-deformations due to rotations are considered in the initial conditions. Furthermore, it is the first time that a discussion is made regarding the range of the fractional order that is physically acceptable and in harmony with the possible universe events. It is found that the thermoelasticity studies that have used the 1–2 interval for the fractional orders have unintentionally engaged the wrong concept of the thermal jerk. Moreover, results associated with fractional orders that approach unity must be used with care. While the spatial differentiations are treated by the finite elements, the fractional-order expressions are computed numerically based on an approach that overcomes the singularity of the Caputo definition, and the resulting combination of the fractional and integer orders of the partial time differential (integrodifferential) terms are treated by an updating and accumulation numerical schemes that account for the changes that happen to the elements and constituent terms of the system matrices with time. In “Results” section, characteristics of the results of the classical, integer-order LS, and fractional-order LS thermoelasticity models are discussed in detail. The fractional-order model has established additional thermal inertias/damping that increases the lags in the responses, and its combination with the coupling factor leads to increased stiffness and thermal and mechanical inertias, and premature steady-state conditions. Moreover, the successive wave reflections have induced local heating and cooling regions that affected all the thermoelastic responses.
In this research, Blade Element Momentum theory (BEM) is used to design a HAWT blade for a 300 kW horizontal axis wind turbine. The airfoil is RISOe-A1-18, produced by RISOe National Laboratory, ...Denmark. Desirable properties of this airfoil are related to enhancement of aerodynamic and structure interactions. Design parameters considered here are wind tip speed ratio, nominal wind speed and diameter of rotor. The nominal wind speed was obtained from statistical analysis of wind speed data from province of Semnan in Iran. BEM is used for obtaining maximum lift to drag ratio for each elemental constitution of the blade. Obtaining chord and twist distribution at assumed tip speed ratio of blade, the aerodynamic shape of the blade in every part is specified which correspond to maximum accessible power coefficient. The design parameters are trust coefficients, power coefficient, angle of attack, angle of relative wind, drag and lift coefficients, axial and angular induction factors. The blade design distributions are presented versus rotor radius for BEM results. The blade shape then can be modified for ease of manufacturing, structural concerns, and to reduce costs.
Propagation, reflection, and interference of the hygro-thermo-viscoelastic temperature, displacement, and stress waves are investigated here in rotary annular discs under thermal and mechanical ...shocks. It is the first time that simultaneous fractional-order heat transfer, fractional-order moisture concentration/diffusion, and fractional-order constitutive models are employed. Moreover, some fractional-order thermomechanical boundaries are incorporated. Furthermore, the rotational pre-deformations that exist before the shock application are included in the initial conditions. Orders of the Cattaneo–Vernotte/Lord–Shulman (LS) heat conduction and viscoelastic constitutive models are assumed to be fractional. A novel numerical solution scheme is presented for the resulting nonlinear coupled hygro-thermo-viscoelastic integrodifferential governing equations with mixed integer and fractional-order expressions. Discretization of the spatial and time domains is accomplished by the finite element technique and a numerical time-marching scheme that eliminates the numerical singularity of the Caputo definition of the fractional-order derivative and employs an accumulated augmented actuation/self-excitation load matrix to update the damping, stiffness, and force matrices within each time step. The natures of the responses of the integer-order classical and LS models are compared comprehensively with those of the fractional-order thermo-viscoelastic models. The philosophy and physical natures of the fractional orders of the constitutive and heat transfer laws are investigated in depth. The integer-order classical and LS hygro-thermo-viscoelastic results are themselves reported here for the first time. Moreover, the results show that while the magnitude of the radial displacement increases, the amount of the hoop stress decreases by increasing the moisture content. Moreover, increasing the fractional order leads to slower hygro-thermoelastic waves and smaller quantities at the early times of wave propagation, but larger temperature rises and expansions as time elapses.
The degree to which different sinonasal symptoms contribute to the overall quality of life (QOL) detriment in chronic rhinosinusitis (CRS) patients remains unknown. In this study we sought to ...characterize the effect of different CRS symptoms on the general health-related QOL in patients.
We performed a prospective cross-sectional study of 131 adult patients with CRS. Sinonasal symptoms were evaluated using the 22-item Sinonasal Outcomes Test (SNOT-22) and general health-related QOL was evaluated using the EuroQol 5-Dimensional general health-related QOL survey (EQ5D) and visual analog scale (EQ5D-VAS). Health utility values (HUV) were determined using responses to the EQ5D. SNOT-22 scores were broken down into subdomain scores for sleep, nasal, otologic/facial pain and emotional function symptoms.
The otologic/facial pain subdomain score consistently had the largest impact on EQ5D-VAS and HUV. After otologic/facial pain, the sleep subdomain score had the second largest effect while the nasal subdomain score had the least impact on general health-related QOL.
Different types of CRS symptoms - most prominently otologic/facial pain and sleep-related symptoms - and their underlying pathophysiologic mechanisms may differentially affect the general health-related QOL detriment associated with CRS. These findings raise the possibility that treatment of the various symptoms associated with CRS may lead to differential improvement in general-health related QOL.
•Wind power densities are obtained using different extrapolating methods.•Parameters of Weibull distribution function are calculated in center of Iran.•The power density method is found to be the ...most accurate method.•Detailed statistical analysis is conducted for large-scale wind turbine installation.•GIS maps of wind power density are produced and assessed for selected wind sites.
With growing wind turbine sizes and increasing demands for electricity, it is important to determine accurately wind shear profile, up to high altitudes, for large scale wind turbine installation. The installed wind turbine towers in Iran have hardly exceeded the height of 40 m. In this study, the effectiveness of different extrapolation methods are investigated to determine robustly wind speed and wind power density at higher altitudes. As a case study, wind data was collected from the center of Iran which consists of 35 wind stations in nine provinces. For precise evaluation, the wind speed data were recorded based on 10-min average at various heights ranging from 10 m to 100 m and the wind power potential was obtained on both seasonally and daily basis. The widely used Weibull distribution function is selected for which the shape factor and scale parameter are determined using the standard deviation method, the empirical method of Lysen and the power density method at different heights. From the extrapolated wind data, the mean wind speed, wind power density, optimal wind speed, probability and cumulative density distributions are obtained and the geographic information systems maps are produced and discussed. The results indicate that the power density method is the most accurate method for extrapolating wind characteristics. From the results, it is also observed that variation of power density with time is significant. In period I (spring and summer), most parts of the center of Iran have significant potential for installing large scale wind turbines. However in period II (fall and winter), the amount of wind power density decreases considerably. In overall, the north western and north eastern parts of the center of Iran are recommended for large scale wind turbine installation. The methodology discussed here can be equally employed for extrapolating of wind speeds data at any heights within any geographical region.
•The surface temperatures of black and white birds’ wings are investigated.•Experimental thermal analysis of black and white aluminum flat plates is performed.•An experimental study is performed on ...various airfoils with heated top surfaces.•Heated top surfaces are seen to result in an enhanced aerodynamic performance.•Heating the top surface of the wings can enhance the flight efficiency of fixed wing drones.
Applications of unmanned aerial vehicles are becoming more attainable through the increase in system efficiency. As seen in nature, birds like the albatross utilize the temperature effects resulting from their wings’ color to increase their flight efficiency. In this paper, the effects that differences in surface temperatures of birds’ black/white wings, colored flat plates, and airfoils with heating films is investigated. Such effects are applicable to the efficiency of fixed-wing drones. Experimentally, it is observed that the surface temperature of black birds’ wings is over 50% higher than white wings under solar radiation. The application of a novel heated top surface on five airfoils results in the drag coefficient decreasing up to 60% and the lift coefficient increasing up to 70% for some airfoils in specified angles of attack compared to a non-heated top surface. This method of utilizing thermal effects can be considered as a new applicable way to increase the flight efficiency in fixed-wing unmanned aerial vehicles.
•A pitch controlled 200kW HAWT blade is designed with BEM for off-design conditions.•Parametric study conducted on power coefficient, axial and angular induction factors.•The optimal pitch angles ...were determined at off-design operating conditions.
In this paper, a 200kW horizontal axis wind turbine (HAWT) blade is designed using an efficient iterative algorithm based on the blade element momentum theory (BEM) on aerodynamic of wind turbines. The effects of off-design variations of wind speed are investigated on the blade performance parameters according to constant rotational speed of the rotor. The performance parameters considered are power coefficient, axial and angular induction factors, lift and drag coefficients on the blade, angle of attack and angle of relative wind. At higher or lower wind speeds than the designed rated speed, the power coefficient is reduced due to considerable changes in the angle of attacks. Therefore, proper pitch control angles were calculated to extract maximum possible power at various off-design speeds. The results showed a considerable improvement in power coefficient for the pitch controlled blade as compared with the baseline design in whole operating range. The present approach can be equally employed for determining pitch angles to design pitch control system of medium and large-scale wind turbines.
Climate change, global warming, and the recent worldwide economic crisis have emphasized the need for low carbon emissions while also ensuring economic feasibility. In this paper, the status and wind ...power potential of the city of Shahrbabak in Kerman province in Iran was investigated. The technical and economical feasibility of wind turbine installation is presented. The potential of wind power generation was statistically analyzed. The mean wind speed data of three-hour interval long term period from 1997 to 2005 was adopted and analyzed in order to determine the potential of wind power generation. The numerical values of the dimensionless Weibull shape parameter (
k) and Weibull scale parameter (
c) were determined. Annual values of “
k” ranged from 1.725 to 1.930 with a mean value of 1.504, while annual values of “
c” were in the range of 4.848–6.095 with a mean value of 5.314 (m/s). With the average wind power density of 100
W/m
2, it is found that the city is not an appropriate place for construction of large-scale wind power plants, but is suitable for employment of off-grid electrical and mechanical wind driven systems. An economic evaluation was done in order to show feasibility of installing small wind turbines. It was concluded that it costs 18 cents for 1
kW
h which is 5 cents more than the market price. Each turbine of 10
kW can supply power for icebox, washer, water pump, TV, lighting, electrical fan, charger, and air conditioning units for small houses. In order to utilize wind energy in the region, it is recommended to install small size wind turbines for electricity supply of public and public buildings and private houses.
In this study, the measured wind speed data for year 2007 at 10
m, 30
m and 40
m heights for two provinces of Iran, North and South Khorasan, have been statistically analyzed to determine the ...potential of wind power generation. This paper presents the wind energy potential at four zones in these provinces, Bojnourd, Esfarayen of North Khorasan province and Nehbandan, and Fadashk of South Khorasan province. The objective is to evaluate the most important characteristic of wind energy in the studied sites. The statistical attitudes permit us to estimate the mean wind speed, the wind speed distribution function, the mean wind power density in the sites at the height of 10
m, 30
m and 40
m. Also, three new types of wind rose diagrams were shown.
There have been several attempts to modify the surface characteristics of tissue engineering implants in order to stimulate specific characteristics. In this research, a single layer of ...hydroxyapatite (HA) and a new double-layer of HA/Al2O3-SiO2 nanocomposites (SiO2, 10, 20, 30 wt%) were deposited, respectively, on the surface of titanium implants by a plasma spray technique. The results indicated that the applied coating systems featured some specific characteristics on the surface such as higher surface roughness and hydrophilicity resulting in a better cellular response and apatite forming ability in vitro, compared to the bare titanium sample. In addition, among different applied coating, the double layer plasma-sprayed HA/Al2O3-20%wt SiO2 coating has shown an enhanced cellular behavior and biocompatibility compared to the single-layer HA. In conclusion, the new bi-layer coatings could significantly affect the surface characteristics of the implants for better biological response without deteriorating the basic characteristics of the implants.
•A plasma-sprayed double-layer coating as biocompatible and bioactive coating•Bi-layer plasma-sprayed coating and improving roughness and wettability•Increasing the cell viability and proliferation by HA/Al2O3-SiO2 plasma sprayed coating
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