Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort:
Hottest Latest Alphabetical (A-Z) Alphabetical (Z-A)
Type:
All Topic Review Biography
Topic Review
SpaceX Rocket Engines
Since the founding of SpaceX in 2002, the company has developed four families of rocket engines — Merlin, Kestrel, Draco and SuperDraco — and is currently developing another rocket engine: Raptor.
  • 2.0K
  • 17 Oct 2022
Topic Review
Micro-Electromechanical Systems Vibrating Gyroscopes
Micro-electromechanical systems (MEMS) vibrating gyroscopes have gained a lot of attention because of their low power consumption, easy integration, and low fabrication cost. The usage of the gyroscope equipped with an inertial measurement unit has increased tremendously, with applications ranging from household devices to smart electronics to military equipment. However, reliability issues are still a concern when operating this inertial sensor in harsh environments, such as to control the movement and alignment of mini-satellites in space, tracking firefighters at an elevated temperature, and assisting aircraft navigation in gusty turbulent air. 
  • 2.0K
  • 18 Oct 2022
Topic Review
Hybrid Prognostic Approaches of Aircraft Systems and Components
Prognostic and health management (PHM) plays a vital role in ensuring the safety and reliability of aircraft systems. The process entails the proactive surveillance and evaluation of the state and functional effectiveness of crucial subsystems. The principal aim of PHM is to predict the remaining useful life (RUL) of subsystems and proactively mitigate future breakdowns in order to minimize consequences. The achievement of this objective is helped by employing predictive modeling techniques and doing real-time data analysis. The incorporation of prognostic methodologies is of utmost importance in the execution of condition-based maintenance (CBM), a strategic approach that emphasizes the prioritization of repairing components that have experienced quantifiable damage. Multiple methodologies are employed to support the advancement of prognostics for aviation systems, encompassing physics-based modeling, data-driven techniques, and hybrid prognosis. 
  • 2.0K
  • 10 Oct 2023
Topic Review
Air Mass
In astronomy, air mass or airmass is a measure of the amount of air along the line of sight when observing a star or other celestial source from below Earth's atmosphere (Green 1992). It is formulated as the integral of air density along the light ray. As it penetrates the atmosphere, light is attenuated by scattering and absorption; the thicker atmosphere through which it passes, the greater the attenuation. Consequently, celestial bodies when nearer the horizon appear less bright than when nearer the zenith. This attenuation, known as atmospheric extinction, is described quantitatively by the Beer–Lambert law. "Air mass" normally indicates relative air mass, the ratio of absolute air masses (as defined above) at oblique incidence relative to that at zenith. So, by definition, the relative air mass at the zenith is 1. Air mass increases as the angle between the source and the zenith increases, reaching a value of approximately 38 at the horizon. Air mass can be less than one at an elevation greater than sea level; however, most closed-form expressions for air mass do not include the effects of the observer's elevation, so adjustment must usually be accomplished by other means. Tables of air mass have been published by numerous authors, including Bemporad (1904), Allen (1976), and Kasten and Young (1989).
  • 1.8K
  • 11 Oct 2022
Topic Review
Life Cycle Assessment in Aviation
With growing environmental awareness and the resulting pressure on aviation, ecological impact assessments are becoming increasingly important. Life cycle assessment has been widely used in the literature as a tool to assess the environmental impact of aircraft. In the following, a brief overview of the existing research on the topic of life cycle assessment in aviation is given. This is concluded with a short summary and an introduction to a possible combination with discrete-event simulation.
  • 1.7K
  • 09 Sep 2022
Topic Review Peer Reviewed
Ionospheric Remote Sensing with GNSS
The Global Navigation Satellite System (GNSS) plays a pivotal role in our modern positioning, navigation and timing (PNT) technologies. GNSS satellites fly at altitudes of approximately 20,000 km or higher. This altitude is above an ionized layer of the Earth’s upper atmosphere, the so called “ionosphere”. Before reaching a typical GNSS receiver on the ground, GNSS satellite signals penetrate through the Earth’s ionosphere. The ionosphere is a plasma medium consisting of free charged particles that can slow down, attenuate, refract, or scatter the GNSS signals. Ionospheric density structures (also known as irregularities) can cause GNSS signal scintillations (phase and intensity fluctuations). These ionospheric impacts on GNSS signals can be utilized to observe and study physical processes in the ionosphere and is referred to ionospheric remote sensing. This entry introduces some fundamentals of ionospheric remote sensing using GNSS. 
  • 1.6K
  • 13 Apr 2022
Topic Review
Astrophotography
Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object (the Moon) was taken in 1840, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. Besides being able to record the details of extended objects such as the Moon, Sun, and planets, modern astrophotography has the ability to image objects invisible to the human eye such as dim stars, nebulae, and galaxies. This is done by long time exposure since both film and digital cameras can accumulate and sum photons over these long periods of time. Photography using extended exposure-times revolutionized the field of professional astronomical research, recording hundreds of thousands of new stars, and nebulae invisible to the human eye. Specialized and ever-larger optical telescopes were constructed as essentially big cameras to record images on photographic plates. Astrophotography had an early role in sky surveys and star classification but over time it has given way to more sophisticated equipment and techniques designed for specific fields of scientific research, with image sensors becoming just one of many forms of sensor. Today, astrophotography is mostly a subdiscipline in amateur astronomy, usually seeking aesthetically pleasing images rather than scientific data. Amateurs use a wide range of special equipment and techniques.
  • 1.6K
  • 22 Nov 2022
Topic Review
Developing a Finite Element Model through LS-DYNA
Robust finite element models are utilised for their ability to predict simple to complex mechanical behaviour under certain conditions at a very low cost compared to experimental studies, as this reduces the need for physical prototypes while allowing for the optimisation of components. 
  • 1.5K
  • 28 Mar 2022
Topic Review
Classification of Unmanned Systems
The autonomous and semi-autonomous multi-agent systems have as much variation and as wide a range of applications as those in the modern mechatronics and robotics fields do. The advance of collaborative swarms of Unmanned Ground Vehicles (UGVs) and drones that are able to operate, navigate, communicate, and even install and assemble “each other” as a symbiotic team will play a critical role in the industry, science, and society in the future
  • 1.5K
  • 08 Mar 2023
Topic Review
Mobile Launcher Platform
A mobile launcher platform, also known as mobile launch platform, is a steel structure used to support a large multistage space vehicle which is assembled (stacked) vertically in an integration facility (e.g. the Vehicle Assembly Building) and then transported by a crawler-transporter (CT) to a launch pad. This becomes the support structure for launch. Alternatives to this method include horizontal assembly and transport to the pad, as used by Russia; and assembling the vehicle vertically on the launch pad, as the United States used for smaller launch vehicles. The use of mobile launcher platforms dates back to the "Integrate-Transfer-Launch" (ITL) concept developed in 1965 for the Titan III launched from Cape Canaveral Space Launch Complex 40 and 41, and was adopted in 1966 for the Saturn V vehicle launched from Kennedy Space Center Launch Complex 39. Launch Complex 39 and 41 continue to use this concept.
  • 1.5K
  • 11 Nov 2022
  • Page
  • of
  • 20
Featured Entry Collections
>>

Featured Books

>>
Encyclopedia of Social Sciences
Encyclopedia of COVID-19
Encyclopedia of Fungi
Encyclopedia of Digital Society, Industry 5.0 and Smart City
Feedback