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Conducting Science-Based Environmental Investigations
Published in Daniel T. Rogers, Fundamentals of Environmental Law and Compliance, 2023
Geophysical investigations include the following techniques and benefits:Electrical resistivity: Electrical resistivity measures the apparent resistivity averaged over a volume of material (ASTM 1999a).Electromagnetics: Electromagnetic methods measure the conductivity of subsurface materials and are frequently used to detect buried metal objects (ASTM 2000a).Gravity survey: Gravity or microgravity surveys measure changes in subsurface density (ASTM 1999b).Ground-penetrating radar: Ground-penetrating radar (GPR) uses high-frequency electromagnetic waves to evaluate subsurface strata (ASTM 2005b).Borehole geophysics: Borehole geophysics uses instruments to measure and record different properties outside of a well or borehole as the instrument is lowered down the borehole (ASTM 2005c, Keys 1990).Seismic refraction and reflection. Seismic refraction and reflection measurements involve the measurement of seismic waves traveling through the subsurface (ASTM 2000b).
Introduction
Published in Mukai Kusuhiro, Matsushita Taishi, Interfacial Physical Chemistry of High-Temperature Melts, 2019
Mukai Kusuhiro, Matsushita Taishi
With the development of satellites, a gravity term as a variable can be expanded from a conventional gravitational field on the ground to microgravity (so-called zero gravity). On the ground, the density convection generated by gravity cannot be eliminated but disappears under microgravity conditions. Meanwhile, in the process of making crystals from a molten state, a temperature gradient always exists. Therefore, the Marangoni convection caused by a surface tension gradient induced by the temperature gradient cannot be avoided. In contrast, under the condition where the surface tension gradient can be arbitrarily controlled, the Marangoni convection can be observed by separating it from the density convection. Owing to the advent of such research environment, research on Marangoni convection itself using the microgravity condition or that related to materials processing has been extensively conducted in the past. Some such studies were reviewed by an author in 1985.3 Other research topics related to Marangoni convection include lubrication,4,5 the abnormal acceleration phenomenon of aqueous surfactant solution in front of an overflow weir,6 the behavior of liquid crystal,7 relations with the convection of a liquid thin film (so-called Benard–Marangoni convection),8 and the concept of infrared-visible image converters.9
Geophysical investigation techniques: gravity
Published in Ian Acworth, Investigating Groundwater, 2019
An application of the gravity technique known as microgravity also exists. Microgravity surveys are particularly useful for finding buried shafts. This is a problem often encountered in the redevelopment of urban land. Microgravity can also be used to find sink holes in limestone terrain. Burger (1992) cites an example of gravity used to find the extent of the cone of depression caused by a pumping test in an unconfined aquifer. Finally, microgravity can be used to determine the extent and depth of a completed landfill, some time after the records have been lost!
Ground Test and on-Orbit Verification of a Mechanically Pumped Two-Phase Loop Using for Thermal Control of Spacecraft
Published in Heat Transfer Engineering, 2023
Qingliang Meng, Zhenming Zhao, Xianggui Chen
In general, the current research on MPTL systems mainly focused on testing the system’s performance and discussing the dynamic behaviors of system under different conditions on the ground. However, there are few studies on the flow and heat transfer characteristics of MPTL system under microgravity, as well as the comparison between microgravity and normal gravity, which limits the availability of the system in the space area. Normal gravity and microgravity will have different effects on MPTL system due to the large density difference between vapor and liquid of working fluid. Because the influence of buoyancy is weakened strongly, the flow patterns in microgravity is believed inherently simpler than those in normal gravity [26]. In addition, flow boiling can augment critical heat flux in microgravity by depending on bulk liquid motion to flush bubbles away and to replenish the wall with bulk liquid [27]. Despite these highly acknowledged merits of flow boiling, very few flow boiling tests have been carried out to date due to the high complexity and high cost of test facilities for microgravity. Flow boiling tests in microgravity also require a longer test duration to achieve the steady state, which make them difficult to carry out in the drop towers or parabolic flight aircraft. Hence, there is a severe shortage in the theory of flow boiling in microgravity. For the MPTL system, these characteristics under microgravity condition are crucial, and they will directly affect the safety of its on-orbit operation and the success of aerospace missions.
Manned space travel: from a race between nations to a race against the environmental stressors beyond earth
Published in Journal of Environmental Science and Health, Part C, 2021
At the altitude at which the ISS circles the Earth, gravity is still about 90% of that experienced on the Earth’s surface. However, because the ISS is essentially in a state of continuous freefall, gravity experience onboard the ISS is minimal and referred to as microgravity. Microgravity will also be experienced by crew members in space crafts that go beyond the gravity pull of the Earth. Although research is performed to build artificial gravity onboard space crafts, this technology is not yet available. Missions to the surface of other space objects will also be associated with different levels of gravity compared to the Earth. Gravity on the lunar surface is only about one sixth that of the Earth, and gravity on the surface of Mars is roughly one third.
Boundary Layer Effect on Opposed-Flow Flame Spread and Flame Length over Thin Polymethyl-Methacrylate in Microgravity
Published in Combustion Science and Technology, 2018
Luca Carmignani, Subrata Bhattacharjee, Sandra L. Olson, Paul V. Ferkul
In a microgravity environment, in the absence of buoyancy induced flow, the flow velocity can be arbitrarily small. It is well known that, at low velocities, the residence time at the flame leading edge can be large enough for radiation to become a significant mechanism of heat loss (T’ien, 1986). In fact, flow velocities below a critical value cause the flame to extinguish. This quenching velocity in the radiative regime is the counter part of the blow-off velocity in the kinetic regime.