Optimum Process Parameters and Thermal Properties of Moisture Content Reduction in Water Yam Drying
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The determination of optimum process parameters for moisture content reduction in water yam drying using a hot air dryer was the aim of this work. Gravimetric method was used to determine the moisture content. Design of experiment was used with slice thickness, airspeed and temperature as the independent factors. Thermal properties such as effective moisture diffusivity and activation energy were determined. The result showed that slice thickness, airspeed and temperature have significant influence on the moisture content reduction. The effective moisture diffusivity ranged from 2.84 x 10-5 m2/s to 8.10 x 10-5 m2/s. The activation energy was 30.592kJ/mol. Minimum moisture content value of 11.98% was obtained at slice thickness of 2mm, airspeed of 2 m/s and temperature of 70oC. The quadratic model best described the drying process. The hot air dryer can conveniently be used for moisture content reduction in water yam slices which will increase its shelf life.Keywords:
Gravimetric analysis
Airspeed
The article discusses an issue of estimating the airspeed of an autonomous flying vehicle. Airspeed is the difference between ground speed and wind speed. It is desirable to know any two among the three speeds for navigation, guidance and control of an autonomous vehicle. For example, ground speed and position are used to guide a vehicle to a target point and wind speed and airspeed are used to maximize flight performance such as a gliding range. However, the target vehicle has not an airspeed sensor but a ground speed sensor (GPS/INS). So airspeed or wind speed has to be estimated. Here, airspeed is to be estimated. A vehicle's dynamics and its dynamic parameters are used to estimate airspeed with attitude and angular speed measurements. Kalman filter is used for the estimation. There are also two major sources arousing a robust estimation problem; wind speed and altitude. Wind speed and direction depend on weather conditions. Altitude changes as a vehicle glides down to the ground. For one reference altitude, multiple model Kalman filters are pre-designed based on several reference airspeeds. We call this group of filters as a cluster. Filters of a cluster are activated simultaneously and probabilities are calculated for each filter. The probability indicates how much a filter matches with measurements. The final airspeed estimate is calculated by summing all estimates multiplied by probabilities. As a vehicle glides down to the ground, other clusters that have been designed based on other reference altitudes are activated. Some numerical simulations verify that the proposed method is effective to estimate airspeed.
Airspeed
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Abstract In the flight test, many test subjects need to enter the large airflow angle. Due to the large airflow angle, the position error of air data sensor is big, and the altitude and airspeed of the aircraft are not accurate, which not only affects the effectiveness of the test results, but also affects the safety of the test flight. This paper proposes two real-time altitude and airspeed estimation methods, including the GPS method and constant wind field method. The GPS method is commonly used in the airspeed calibration, which mainly uses the GPS height change to correct the static pressure, but it depends on the aircraft total pressure sensor to get the airspeed. The constant wind field method directly calculates the true airspeed not depending on the pressure measurement, but it is greatly affected by the wind stability. During the flight test, using this method, the real-time monitoring can provide pilots with accurate altitude and airspeed reference.
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Flight test
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Abstract : Conventional pitot-static airspeed measurement systems do not yield accurate measurements when aircraft speed is below 40 knots. Recent studies have demonstrated that neural network approaches for predicting airspeed are quite promising. In this thesis, a back-propagation neural network is used to predict the airspeed of UH-60A and OH-6A helicopters in the low speed environment. The input data to the neural networks were obtained using the FLIGHTLAB flight simulator. The results obtained by flight simulation were validated by comparison to results of a previous study of the UH-60A helicopter based on actual flight data. The results of the work performed for this thesis show that at sea level the UH-60A low airspeed can be predicted with an accuracy of +/- 0.71 knots and +/- 0.88 knots for out of ground effect and in ground effect conditions respectively. OH-6A analyses were performed at two pressure altitudes. At sea level the OH-6A airspeed can be predicted with an accuracy +/- 0.75 knots when the aircraft is out of ground effect and +/- 0.88 knots when the helicopter is in ground effect. At a pressure altitude of 6000 feet OH-6A airspeed can be predicted with an accuracy of +/- 0.64 knots for both flight conditions.
Airspeed
Pitot tube
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Calibration of the airspeed indicator is important for accurate measurement of flight speed. This chapter introduces the various types of airspeeds, including indicated, calibrated, equivalent, and true airspeed. Various error sources are discussed, with a particular emphasis on position error, which dominates the difference between indicated and calibrated airspeeds. Position error, resulting from an inaccuracy in measurement of freestream static pressure, is shown to affect both the airspeed and altitude measurements on an aircraft. Flight testing methods for calibrating for position error are introduced, with an emphasis on global positioning system (GPS)-derived measurements of ground speed over three separate headings in order to find true airspeed as well as wind speed in flight.
Airspeed
Position (finance)
Freestream
Position error
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Errors in navigational instruments can significantly affect flight safety. Airspeed is a key piece of navigational data that depends on accurately measured air pressure, which in turn depends on accurately measured air temperature. Instead of measuring the outside air temperature in real time, cockpit instruments are preprogrammed with standard air temperature values for different flight altitudes, but atmospheric conditions can cause the actual temperature to deviate substantially from these standard values. In the present study, test flights were conducted under various atmospheric conditions to examine how the actual temperature affects the deviation of the actual airspeed from the measured airspeed. Results indicate that the differences between the actual and the standard temperature, and not those between the actual and the standard pressure, are the primary cause of deviations of the measured from the actual airspeed. The results of this study may help establish aircraft flight models based on more accurate estimates of navigational parameters.
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Cockpit
Air navigation
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Solid thermal diffusivity is very important to study unsteady heat conduction under low temperature.In order to study solid thermal diffusivity under low temperature,sample thermal diffusivity under different temperature is computed in term of thermal diffusivity theory model in the paper.Besides,function relation between laser frequency and phase lag is gained by numerical simulation.The two groups of data are approximately equal by contrasting the numerical result and experimental result.The research indicates that solid thermal diffusivity could be measured availably by laser photothermal.Numerical simulation of solid thermal diffusivity under low temperature shows that solid thermal diffusivity changes remarkably when the scope of temperature is from 20 K to 80 K,however,the change is less from 80 K to 300 K.
Laser flash analysis
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The speed that an airplane travels with respect to the air mass is seldom identical to the speed measured with respect to the ground. This is, of course, due to the influence of wind on the airplane's movement. Similarly, the air distance and the ground distance that an airplane covers are rarely the same. The customary units that are used for the measurement of air or ground distance are nautical miles (nm), kilometers (km), and statute miles (mi). For navigation purposes, the true airspeed (TAS) is associated with the airplane's heading. An airplane's TAS will differ from its speed over the ground in the presence of wind. This chapter describes the different speeds that are encountered in airplane performance analysis namely: true airspeed and ground speed, Mach number, equivalent airspeed, calibrated airspeed, and indicated airspeed. It discusses the relationships between these speeds.
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Airplane
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