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List of Human Spaceflight Programs
This is a list of human spaceflight programs, including successful programs, programs that were canceled, and programs planned for the future. The criteria for what constitutes human spaceflight vary. The FAI defines spaceflight as any flight over 100 kilometers (62 mi). In the U.S. professional, military, and commercial astronauts who travel above an altitude of 80 kilometers (50 mi) are awarded astronaut wings. This article follows the FAI definition of spaceflight. Until the 21st century, human spaceflight programs were sponsored exclusively by governments, through either the military or civilian space agencies. With the launch of the privately funded SpaceShipOne in 2004, a new category of human spaceflight programs – commercial human spaceflight – arrived.
  • 1.9K
  • 09 Nov 2022
Topic Review Peer Reviewed
Reinforced Concrete Infilled Frames
Masonry-Infilled Reinforced Concrete Frames are a very widespread structural typology all over the world for civil, strategic or productive uses. The damages due to these masonry panels can be life threatening to humans and can severely impact economic losses, as shown during past earthquakes. In fact, during a seismic event, most victims are caused by the collapse of buildings or due to nonstructural elements. The damage caused by an earthquake on nonstructural elements, i.e., those not belonging to the actual structural body of the building, is important for the purposes of a more general description of the effects and, of course, for economic estimates. In fact, after an earthquake, albeit of a low entity, it is very frequent to find even widespread damages of nonstructural elements causing major inconveniences even if the primary structure has reported minor damages. In recent years, many territories have been hit worldwide by strong seismic sequences, which caused widespread damages to the nonstructural elements and in particular to the masonry internal partitions and the masonry infill panels of the buildings in reinforced concrete, with damage to the floor and out-of-plane expulsions/collapses of single layers. Unfortunately, these critical issues have arisen not only in historic, but also in recent buildings with reinforced concrete, in many cases exhibiting inadequate seismic behavior, only partly attributable to the intrinsic vulnerability of the masonry panels against seismic actions. Such problems are due to the following aspects: lack of attention to construction details in the realization of the construction, use of poor-quality materials, and above all lack of design tools for the infill masonry walls. In 2018, regarding the design of nonstructural elements, the formulation of floor spectra has been recently introduced in Italy. This entry article wants to focus on all these aspects, describing the state of the art, the literature studies and the design problems to be solved.
  • 1.8K
  • 13 Apr 2022
Topic Review
Titanium Aluminides
Titanium aluminides (TiAl) have the potential of substituting nickel-based superalloys (NBSAs) in the aerospace industries owing to their lightweight, good mechanical and oxidation properties. Functional simplicity, control of sintering parameters, exceptional sintering speeds, high reproducibility, consistency and safety are the main benefits of spark plasma sintering (SPS) over conventional methods. Though TiAl exhibit excellent high temperature properties, SPS has been employed to improve on the poor ductility at room temperature. Powder metallurgical processing techniques used to promote the formation of refined, homogeneous and contaminant-free structures, favouring improvements in ductility and other properties are discussed. This article further reviews published work on phase constituents, microstructures, alloy developments and mechanical properties of TiAl alloys produced by SPS. Finally, an overview of challenges in as far as the implementation of TiAl in industries of interest are highlighted.
  • 1.9K
  • 07 Jan 2021
Topic Review
Solar PV Monitoring
Solar Photovoltaic (PV) energy is a clean, attractive, and secure source of electricity generation. Due to its expanse usage around the globe, the development of an advanced monitoring method is crucial. PV performance can be affected by various environmental factors such as soiling, temperature, irradiance etc. Thus, solar PV accuracy and performance can be improved by employing an efficient solar PV real-time monitoring system. 
  • 1.9K
  • 12 Aug 2021
Topic Review
Non-Mechanical Hybrid Hydrogen Compression
Non-mechanical hybrid hydrogen compressors consists of a first electrochemical compression stage followed by a second one based on the adsorption-desorption of hydrogen on microporous materials. They allow compressing hydrogen up to 70 MPa. Non-mechanical hybrid hydrogen compressors can be a valid alternative to the mechanical compressors. 
  • 1.9K
  • 29 Jun 2020
Topic Review
Void Nucleation in Metals
The research discussed about the development of micro-voids in metals, leading to ductile fracture, associated with plastic deformation, without taking into account the cleavage mechanism. Particular emphasis was placed on the results of observations and experimental studies, the characteristics of the phenomenon itself, without in-depth analysis in the field of widely used FEM modelling. The mechanism of void development as a fracture mechanism is presented. Observations of the nucleation of voids in metals from the turn of the 1950s and 1960s to the present day have been described. The nucleation mechanisms related to the defects of the crystal lattice as well as those resulting from the presence of second phase particles were characterised.
  • 1.9K
  • 08 Oct 2022
Topic Review
Batavia (Ship)
Batavia (Dutch pronunciation: [baːˈtaːviaː] (listen)) was a ship of the Dutch East India Company (VOC). It was built in Amsterdam, Dutch Republic, in 1628, and armed with 24 cast-iron cannons and a number of bronze guns. Batavia was shipwrecked on her maiden voyage, and was made famous by the subsequent mutiny and massacre that took place among the survivors. A twentieth-century replica of the ship is also called the Batavia and can be visited in Lelystad, Netherlands.
  • 1.9K
  • 15 Nov 2022
Topic Review
Remediation of Petroleum Contaminated Soils
Due to the development of the petroleum industrial, numerous petroleum pollutants are discharged into the soil, destroying the structure and properties of the soil, and even endangering the health of plants and humans. Microbial remediation and combined microbial methods remediation of petroleum-contaminated soil are currently recognized remediation technologies, which have the advantages of no secondary pollution, low cost and convenient operation. This entry includes the sources and composition of petroleum pollutants and their harm to soil, plants and humans. Subsequently, the focus is on the mechanism of microbial method and combined microbial methods to degrade petroleum pollutants. Finally, the challenges of the current combined microbial methods are pointed out.
  • 1.9K
  • 28 Sep 2021
Topic Review
CO2 and H2S Separation Technologies
The emerging economic activities, modernization of technology and progressive transition from coal utilization to low-carbon fuel drive the rising energy demand. Natural gas is well-known as clean energy resources for electricity generation and fuel for transportation. Currently, CO2 and H2S content in gas fields accounts for up to 90% and 15%, respectively. Apart from fulfilling the market demand, the removal of these contaminants from natural gas is critical due to their corrosive natures, low heating value of natural gas and  greenhouse gas effect. To date, numerous gas fields remain unexplored due to high presence of contaminants. Several technologies such as absorption, adsorption, membrane separation and cryogenic distillation have been developed for natural gas sweetening. This entry comprehensively discussed the mechanisms and state-of-the-art of these conventional technologies.
  • 1.9K
  • 03 Mar 2022
Topic Review
Kepler (Spacecraft)
Kepler is a space observatory launched by NASA to discover Earth-size planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched on March 7, 2009, into an Earth-trailing heliocentric orbit. The principal investigator was William J. Borucki. Designed to survey a portion of our region of the Milky Way to discover Earth-size exoplanets in or near habitable zones and estimate how many of the billions of stars in the Milky Way have such planets, Kepler's sole scientific instrument is a photometer that continually monitors the brightness of approx 150,000 main sequence stars in a fixed field of view. These data are transmitted to Earth, then analyzed to detect periodic dimming caused by exoplanets that cross in front of their host star. Kepler is part of NASA's Discovery Program of relatively low-cost, focused primary science missions. The telescope's construction and initial operation were managed by NASA's Jet Propulsion Laboratory, with Ball Aerospace responsible for developing the Kepler flight system. The Ames Research Center is responsible for the ground system development, mission operations since December 2009, and scientific data analysis. The initial planned lifetime was 3.5 years, but greater-than-expected noise in the data, from both the stars and the spacecraft, meant additional time was needed to fulfill all mission goals. Initially, in 2012, the mission was expected to be extended until 2016, but on July 14, 2012, one of the spacecraft's four reaction wheels used for pointing the spacecraft stopped turning, and completing the mission would only be possible if all other reaction wheels remained reliable. Then, on May 11, 2013, a second reaction wheel failed, disabling the collection of science data and threatening the continuation of the mission. On August 15, 2013, NASA announced that they had given up trying to fix the two failed reaction wheels. This meant the current mission needed to be modified, but it did not necessarily mean the end of planet hunting. NASA had asked the space science community to propose alternative mission plans "potentially including an exoplanet search, using the remaining two good reaction wheels and thrusters". On November 18, 2013, the K2 "Second Light" proposal was reported. This would include utilizing the disabled Kepler in a way that could detect habitable planets around smaller, dimmer red dwarfs. On May 16, 2014, NASA announced the approval of the K2 extension. (As of January 2015), Kepler and its follow-up observations had found 1,013 confirmed exoplanets in about 440 star systems, along with a further 3,199 unconfirmed planet candidates.[upper-alpha 2] Four planets have been confirmed through Kepler's K2 mission. In November 2013, astronomers estimated, based on Kepler space mission data, that there could be as many as 40 billion rocky, Earth-size exoplanets orbiting in the habitable zones of Sun-like stars and red dwarfs within the Milky Way. It is estimated that 11 billion of these planets may be orbiting Sun-like stars. The nearest such planet may be 3.7 parsecs (12 ly) away, according to the scientists. On January 6, 2015, NASA announced the 1,000th confirmed exoplanet discovered by the Kepler Space Telescope. Four of the newly confirmed exoplanets were found to orbit within habitable zones of their related stars: three of the four, Kepler-438b, Kepler-442b and Kepler-452b, are almost Earth-size and likely rocky; the fourth, Kepler-440b, is a super-Earth. On May 10, 2016, NASA verified 1,284 new exoplanets found by Kepler, the single largest finding of planets to date. Kepler data has also helped scientists observe and understand supernovae; measurements were collected every half-hour so the light curves were especially useful for studying these types of astronomical events.
  • 1.9K
  • 20 Oct 2022
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