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From Screws to Space Stations: All Engineering is Important
Published in Radovan Zdero, Practical Career Advice for Engineers, 2021
But, how does the ISS stay in orbit? We know from orbital physics that any object launched from the Earth must reach an escape velocity to overcome the planet’s gravity in order to enter orbit at the same velocity. Otherwise, it just crashes back into the planet. Like all artificial near-Earth satellites, the ISS travels in a circular orbit at a velocity that is mathematically expressed as V = GM/R, where V is the escape or orbital velocity, G is Newton’s universal gravitational constant, M is the mass of the Earth, and R is the orbital radius. So, the farther out the desired orbital path is from the planet, the slower the escape velocity that’s required, and the slower the orbital velocity that’s maintained. For the ISS, the orbital altitude is 400 km above the Earth at an orbital velocity of 29,000 km/hour.
Apple
Published in Debashis Mandal, Ursula Wermund, Lop Phavaphutanon, Regina Cronje, Temperate Fruits, 2021
Graciela María Colavita, Mariela Curetti, Dolores Raffo, María Cristina Sosa, Laura I. Vita
Most traditional apple cultivars have a high cold requirement (1000–1600 chilling hours), so they cannot be cultivated properly at low latitudes (Ryugo, 1988). If this requirement is not fulfilled, budding is unequal and poor. Some cultivars with a low cold requirement were obtained (100,300 chilling hours), which allows apple cultivation in tropical regions, such as Brazil (Sansavini et al., 2012). Because of this cold requirement, the most important areas for apple production are found between 35° and 50° latitudes in both hemispheres. Apples planted in regions of latitudes lower than 35° must have a low cold need or must be cultivated at a high altitude, which allows them to accumulate winter cold need and go out of dormancy (Westwood, 1993). Temperature decreases as altitude increases. Thermal vertical gradient presents an average value of 0.64 °C every 100 m in atmospheric stability conditions (Sansavini et al., 2012). After winter dormancy, apple requires heat accumulation to sprout. Apple requirement is about 6900 GDH (Growth Degree Hours) according to Richardson model (Sansavini et al., 2012). In most cultivars, apples reach ripening between 120 and 150 days after full bloom. In general, apples require 500–600 mm of rainfall for irrigation during growing season. Rainfall is considered an adverse factor because most apple production regions are irrigated, and rainfall increases fungal and bacterial disease incidence (Jackson, 2003). Moreover, during bloom, rainfall can set a limit to dispersal of pollen grains, wash them from stigmas, and even hinder insect pollinator flight (Sansavini et al., 2012).
Atmosphere
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
The troposphere, the lowest layer of the atmosphere, extends upward to the tropopause, which begins at altitudes of 8–18 km (4.96–11.2 mi.) depending on the latitude and time of year. The troposphere is at its maximum height over the equator and its lowest height over the poles. Temperature decreases steadily from an average of ~15°C (59°F) to −60°C (−76°F) at 15 km (9.3 mi.). On average, temperature decreases at a rate of −6.5°C/km. This progressive temperature decline is due to the increasing distance from the sun-warmed Earth.
A new approach to LST modeling and normalization under clear-sky conditions based on a local optimization strategy
Published in International Journal of Digital Earth, 2022
Majid Kiavarz, Mohammad Karimi Firozjaei, Seyed Kazem Alavipanah, Quazi K. Hassan, Yoann Malbéteau, Si-Bo Duan
In a troposphere, assuming a constant time and geographical location, air pressure decreases as altitude increases. This is an adiabatic process in which there is a reduction in internal air energy and a drop in air temperature (Jacobson 2005). This is suggestive of the effect of NSTLR, most evident at night and influenced by solar and topographic effect variables in daytime (Firozjaei et al. 2020). Theoretically, the NSTLR value is about 9.8°C km−1 under adiabatic arid conditions, about 6-7°C km−1 under adiabatic semi-arid conditions at lower elevations than 10 km, and about 3.6°C km−1 under adiabatic wet conditions (Danielson, Levin, and Abrams 2003; Rolland 2003; Minder, Mote, and Lundquist 2010). Practically, NSTLR should be estimated according to the time and geographical location (Danielson, Levin, and Abrams 2003; Rolland 2003; Minder, Mote, and Lundquist 2010). Accordingly, GDEM was used in the proposed model for modeling NSTLR (Boudhar et al. 2011).
Thermal simulation of Alpha Magnetic Spectrometer in orbit
Published in Numerical Heat Transfer, Part A: Applications, 2023
The ISS orbital period and exposure time within an orbital period are determined by the ISS orbital altitude, which varies from 370 km to 460 km. Normally, the ISS orbital altitude is maintained at 400 km. Angle β represents the relative position between the sun and the ISS orbital plane, and it varies periodically between −75.1° and +75.1°. Angle θ indicates the angular distance between the ISS orbital position and the junction with the sun, which varies from 0° to 360°. Solar radiation intensity varies with the distance between the Earth and the sun, which is 1,322 W/m2 at the apogee and 1,414 W/m2 at the perihelion. These orbital parameters determine the external heat fluxes and thus affect the temperature of AMS.
A proposed new model for the prediction of latitude-dependent atmospheric pressures at altitude
Published in Science and Technology for the Built Environment, 2021
In atmospheric science the term “air parcel” is commonly used, which is equivalent to an infinitely small control volume. In an adiabatic atmosphere, there is no exchange of energy between the “air parcel” and the surrounding environment. Furthermore, there is no exchange of mass between the air parcel and the surrounding environment, which means the mass stays constant. With increasing altitude, the change in internal energy of the “air parcel” causes the air to cool. The first law of thermodynamics is applied to determine temperature change with change in altitude: